INTERVIEW

3G

Atunu Gorai

WCDMA Frequency and Spectrum

bull Uplink=1920MHz -1980 MHz

bull Downlink= 2110MHz -2170MHz

bull Bandwidth=60 MHz

Actual BW assign to operator is 5MHz

And out of that 384 MHZ is utilize

In WCDMA frequency reuse factor =1 because time and frequency remains constant

bull Eb NO= Bit energyNoise energy

bull EcNo = Chip Energy Noise Energy

bull EcNo= EbNo - process gain

bull As per EbNo is fixed for each service for Ex voice =2 and video=4

bull EcN0= 2- 10= -8 for voice(for voice -8 is good limit)

bull EcN0= 4-18= -14 for video(for video -14 is good limit)

bull Process gain(voice) = chip ratebit rate= 10dB

bull Process gain (video) = chip rate bit rate= 18dB

bull Chip rate = 384Mchips in WCDMA

Cyclic Redundancy Check (CRC) is used to detect if there are any uncorrected errors left after error correction The next part in the transmitter is Forward Error Correction (FEC) The function of this block is to help the receiver correct bit errors caused by the air interface

The error-protected signal is then multiplied by a particular channelization code to provide the necessary channel separation This is necessary since all the channels will be added together which will produce a composite data stream

Channelization codes

In the downlink the channelization codes are used to separate the different data channels coming from each cell For the dedicated channels this represents the different users since only one scrambling code is used for all downlink transmission from the cell In the uplink the channelization codes are used to separate the different data channels sent from the UE to the each cell The separation of the different UEs will here be done with different scrambling codes The number of codes used in the downlink is restricted to 8192 in total This is done to speed up the process for the UE to find the correct scrambling code 512 of these are primary codes (the rest are secondary codes 15 codes per primary) divided into 64 code groups each group containing 8 different codes The UE can determine which scrambling code group a cell is using by the synchronization procedure (see chapter 5) Note that there are no restrictions for the number of codes generated by the 24 bits start key in the uplink case

Data Drive

bull There is 3 modulation technique QPSK16QAM64QAM

bull For high through put 16QAM and 64QAM should have high Utilization

bull So if There is less Utilization of QPSK in downlink than data throughput is also high

bull CQI is like SQI in speech which ensure good channel quality for data transfer

bull Retransmission of HS- DSCH(High-Speed Downlink Shared Channel) packet is high than also throughput is decreases

bull In case of stationary Data Test- 2Mbits speed can be achieved

bull In case of moving Vehicle ndash 800kbits to 12 Kbits speed can be achieved

bull Application throughput is always 85 of physical layer data rate throughput because at application level IP inclusion and overhead information will be there

bull Latency time is round trip time from server and for 3G it should be 150 ms for 32 bit data

WCDMA Frequency and Spectrum

bull Uplink=1920MHz -1980 MHz

bull Downlink= 2110MHz -2170MHz

bull Bandwidth=60 MHz

Actual BW assign to operator is 5MHz

And out of that 384 MHZ is utilize

In WCDMA frequency reuse factor =1 because time and frequency remains constant

bull Eb NO= Bit energyNoise energy

bull EcNo = Chip Energy Noise Energy

bull EcNo= EbNo - process gain

bull As per EbNo is fixed for each service for Ex voice =2 and video=4

bull EcN0= 2- 10= -8 for voice(for voice -8 is good limit)

bull EcN0= 4-18= -14 for video(for video -14 is good limit)

bull Process gain(voice) = chip ratebit rate= 10dB

bull Process gain (video) = chip rate bit rate= 18dB

bull Chip rate = 384Mchips in WCDMA

Cyclic Redundancy Check (CRC) is used to detect if there are any uncorrected errors left after error correction The next part in the transmitter is Forward Error Correction (FEC) The function of this block is to help the receiver correct bit errors caused by the air interface

The error-protected signal is then multiplied by a particular channelization code to provide the necessary channel separation This is necessary since all the channels will be added together which will produce a composite data stream

Channelization codes

In the downlink the channelization codes are used to separate the different data channels coming from each cell For the dedicated channels this represents the different users since only one scrambling code is used for all downlink transmission from the cell In the uplink the channelization codes are used to separate the different data channels sent from the UE to the each cell The separation of the different UEs will here be done with different scrambling codes The number of codes used in the downlink is restricted to 8192 in total This is done to speed up the process for the UE to find the correct scrambling code 512 of these are primary codes (the rest are secondary codes 15 codes per primary) divided into 64 code groups each group containing 8 different codes The UE can determine which scrambling code group a cell is using by the synchronization procedure (see chapter 5) Note that there are no restrictions for the number of codes generated by the 24 bits start key in the uplink case

Data Drive

bull There is 3 modulation technique QPSK16QAM64QAM

bull For high through put 16QAM and 64QAM should have high Utilization

bull So if There is less Utilization of QPSK in downlink than data throughput is also high

bull CQI is like SQI in speech which ensure good channel quality for data transfer

bull Retransmission of HS- DSCH(High-Speed Downlink Shared Channel) packet is high than also throughput is decreases

bull In case of stationary Data Test- 2Mbits speed can be achieved

bull In case of moving Vehicle ndash 800kbits to 12 Kbits speed can be achieved

bull Application throughput is always 85 of physical layer data rate throughput because at application level IP inclusion and overhead information will be there

bull Latency time is round trip time from server and for 3G it should be 150 ms for 32 bit data

bull Eb NO= Bit energyNoise energy

bull EcNo = Chip Energy Noise Energy

bull EcNo= EbNo - process gain

bull As per EbNo is fixed for each service for Ex voice =2 and video=4

bull EcN0= 2- 10= -8 for voice(for voice -8 is good limit)

bull EcN0= 4-18= -14 for video(for video -14 is good limit)

bull Process gain(voice) = chip ratebit rate= 10dB

bull Process gain (video) = chip rate bit rate= 18dB

bull Chip rate = 384Mchips in WCDMA

Cyclic Redundancy Check (CRC) is used to detect if there are any uncorrected errors left after error correction The next part in the transmitter is Forward Error Correction (FEC) The function of this block is to help the receiver correct bit errors caused by the air interface

The error-protected signal is then multiplied by a particular channelization code to provide the necessary channel separation This is necessary since all the channels will be added together which will produce a composite data stream

Channelization codes

In the downlink the channelization codes are used to separate the different data channels coming from each cell For the dedicated channels this represents the different users since only one scrambling code is used for all downlink transmission from the cell In the uplink the channelization codes are used to separate the different data channels sent from the UE to the each cell The separation of the different UEs will here be done with different scrambling codes The number of codes used in the downlink is restricted to 8192 in total This is done to speed up the process for the UE to find the correct scrambling code 512 of these are primary codes (the rest are secondary codes 15 codes per primary) divided into 64 code groups each group containing 8 different codes The UE can determine which scrambling code group a cell is using by the synchronization procedure (see chapter 5) Note that there are no restrictions for the number of codes generated by the 24 bits start key in the uplink case

Data Drive

bull There is 3 modulation technique QPSK16QAM64QAM

bull For high through put 16QAM and 64QAM should have high Utilization

bull So if There is less Utilization of QPSK in downlink than data throughput is also high

bull CQI is like SQI in speech which ensure good channel quality for data transfer

bull Retransmission of HS- DSCH(High-Speed Downlink Shared Channel) packet is high than also throughput is decreases

bull In case of stationary Data Test- 2Mbits speed can be achieved

bull In case of moving Vehicle ndash 800kbits to 12 Kbits speed can be achieved

bull Application throughput is always 85 of physical layer data rate throughput because at application level IP inclusion and overhead information will be there

bull Latency time is round trip time from server and for 3G it should be 150 ms for 32 bit data

Cyclic Redundancy Check (CRC) is used to detect if there are any uncorrected errors left after error correction The next part in the transmitter is Forward Error Correction (FEC) The function of this block is to help the receiver correct bit errors caused by the air interface

The error-protected signal is then multiplied by a particular channelization code to provide the necessary channel separation This is necessary since all the channels will be added together which will produce a composite data stream

Channelization codes

In the downlink the channelization codes are used to separate the different data channels coming from each cell For the dedicated channels this represents the different users since only one scrambling code is used for all downlink transmission from the cell In the uplink the channelization codes are used to separate the different data channels sent from the UE to the each cell The separation of the different UEs will here be done with different scrambling codes The number of codes used in the downlink is restricted to 8192 in total This is done to speed up the process for the UE to find the correct scrambling code 512 of these are primary codes (the rest are secondary codes 15 codes per primary) divided into 64 code groups each group containing 8 different codes The UE can determine which scrambling code group a cell is using by the synchronization procedure (see chapter 5) Note that there are no restrictions for the number of codes generated by the 24 bits start key in the uplink case

Data Drive

bull There is 3 modulation technique QPSK16QAM64QAM

bull For high through put 16QAM and 64QAM should have high Utilization

bull So if There is less Utilization of QPSK in downlink than data throughput is also high

bull CQI is like SQI in speech which ensure good channel quality for data transfer

bull Retransmission of HS- DSCH(High-Speed Downlink Shared Channel) packet is high than also throughput is decreases

bull In case of stationary Data Test- 2Mbits speed can be achieved

bull In case of moving Vehicle ndash 800kbits to 12 Kbits speed can be achieved

bull Application throughput is always 85 of physical layer data rate throughput because at application level IP inclusion and overhead information will be there

bull Latency time is round trip time from server and for 3G it should be 150 ms for 32 bit data

Channelization codes

In the downlink the channelization codes are used to separate the different data channels coming from each cell For the dedicated channels this represents the different users since only one scrambling code is used for all downlink transmission from the cell In the uplink the channelization codes are used to separate the different data channels sent from the UE to the each cell The separation of the different UEs will here be done with different scrambling codes The number of codes used in the downlink is restricted to 8192 in total This is done to speed up the process for the UE to find the correct scrambling code 512 of these are primary codes (the rest are secondary codes 15 codes per primary) divided into 64 code groups each group containing 8 different codes The UE can determine which scrambling code group a cell is using by the synchronization procedure (see chapter 5) Note that there are no restrictions for the number of codes generated by the 24 bits start key in the uplink case

Data Drive

bull There is 3 modulation technique QPSK16QAM64QAM

bull For high through put 16QAM and 64QAM should have high Utilization

bull So if There is less Utilization of QPSK in downlink than data throughput is also high

bull CQI is like SQI in speech which ensure good channel quality for data transfer

bull Retransmission of HS- DSCH(High-Speed Downlink Shared Channel) packet is high than also throughput is decreases

bull In case of stationary Data Test- 2Mbits speed can be achieved

bull In case of moving Vehicle ndash 800kbits to 12 Kbits speed can be achieved

bull Application throughput is always 85 of physical layer data rate throughput because at application level IP inclusion and overhead information will be there

bull Latency time is round trip time from server and for 3G it should be 150 ms for 32 bit data

Data Drive

bull There is 3 modulation technique QPSK16QAM64QAM

bull For high through put 16QAM and 64QAM should have high Utilization

bull So if There is less Utilization of QPSK in downlink than data throughput is also high

bull CQI is like SQI in speech which ensure good channel quality for data transfer

bull Retransmission of HS- DSCH(High-Speed Downlink Shared Channel) packet is high than also throughput is decreases

bull In case of stationary Data Test- 2Mbits speed can be achieved

bull In case of moving Vehicle ndash 800kbits to 12 Kbits speed can be achieved

bull Application throughput is always 85 of physical layer data rate throughput because at application level IP inclusion and overhead information will be there

bull Latency time is round trip time from server and for 3G it should be 150 ms for 32 bit data

bull The modulation scheme and coding is changed on a per-user basis depending on signal quality and cell usage The initial scheme is Quadrature phase-shift keying (QPSK) but in good radio conditions 16QAM and 64QAM can significantly increase data throughput rates With 5 Code allocation QPSK typically offers up to 18 Mbits peak data rates while 16QAM offers up to 36 Mbits Additional codes (eg 10 15) can also be used to improve these data rates or extend the network capacity throughput significantly

bull Data Throughput will be also depend on MS class which support 510 and 15 codes resp

bull CQI- Channel quality indication may include carrier level received signal strength indication (RSSI) and bit error rate (BER) I

bull Channel quality indicators are messages that are sent on a communication system (such as a mobile communication system) that provide the remote connection (eg base station) with channel quality information

Notes on quantities denoting signal power

KEY PERFORMANCE INDICATORS

Accessability (Call set-up success rate)

Retainability (Dropped calls)

Mobility (Handover success rate)

Integrity (BLER and throughput)

Integrity- quality

Integrity-throughput

What is the major difference in link budgets between UMTS and GSMTDMA In UMTS you generally have a link budget for each service (voice data video etc) in GSM you usually only use 1 for voice Each service has a different EbNo target In UMTS you have to consider the target traffic load you will have and add a noise-rise margin in GSM you may have a slight interference margin but not normally related to traffic In UMTS some services (like voice) will show up as uplink limited but other services (like HSDPA 384kbps service) will show as downlink limited In UMTS you usually have to consider that all users use the same power from the BTS therefore the more number of users the lower the maximumpower available per user (maximum power per connection) which is a starting point in the link budget

KPI Requirements Formula

CPICH RSCP ge-95dBm NA (nbr_of_samples_RSCPgt=-95dBm)

(tot_nbr_of_samples_RSCP)

CPICH EcIo ge-12dB NA (nbr_of_samples_EcIogt=-12dB)

(tot_nbr_of_samples_EcIo)

Voice call setup

success rate Min ge98

(nbr_of_successful_voice_call_setup)

(nbr_of_voice_call_attemp)

Voice call setup time

(Mobile to 1764440)

le10s ge99

(nbr_of_voice_call_setup_timele10s)

(nbr_of_successful_voice_call_setup)

voice_call_setup_time =[T(CC_alerting) - T(first_RRC_connection_request)]

le9s ge95

(nbr_of_voice_call_setup_timele9s)

(nbr_of_successful_voice_call_setup)

voice_call_setup_time =[T(CC_alerting) - T(first_RRC_connection_request)]

Voice call drop rate Max le2 (nbr_of_voice_call_drop)

[(call_duration_time)90sec]

PDP activation

successful rate Min ge99

(nbr_of_PDP_context_activation_accept)

(nbr_of_PDP_context_activation_request)

PDP activation delay le2s ge99

(nbr_of_PDP_activation_delayle2s)

(nbr_of_PDP_context_activation_accept)

PDP_activation_delay= [T(PDP_context_activation_accept)-

T(PDP_context_activation_request)]

PS 384k FTP DL Avg Throughput 280kbps (downloaded_data_kbit)

(data_session_duration)

PS 384k FTP UL Avg Throughput 280kbps (uploaded_data_kbit)

(data_session_duration)

HSDPA FTP Avg Throughput 45Mbps (downloaded_data_kbit)

(data_session_duration)

HSUPA FTP Avg Throughput 11Mbps (uploaded_data_kbit)

(data_session_duration)

KPI calculation

Case 1 Drop due to missing neighbor

Problem Detected Nighbor (DN)

bull UE sends a Measurement Report that contains an event1a means adding a new RL (cell) to Active Set

bull If the reported cell is not in the current neighbor cell list and the reported EcNo is better than the best serving cell EcNo in AS by some dBs (set by a RNC parameter)

bull If for any reason the new cell can not be added to AS call will be released

2 If the UE reconnects to the network immediately after call drop and the scramble of the cell that UE camps on is different from that upon call drop missing neighbor cell is probable Confirm it by measurement control (search the messages back from call drop for the latest intra-frequency measurement control message Check the neighbor cell list of this measurement control message)

3 UEs might report detected set information If corresponding scramblling code information is in the monitor set before call drop the cause must be missing neighbor cell

Weak Coverage

bull Weak coverage usually refers to weak RSCP Uplink or downlink DCH power helps to confirm the weak coverage is in uplink or downlink by the following methods bull If the uplink transmission power reaches the maximum before call drop the uplink BLER is weak the call drop is probably due to weak uplink coverage bull Out of Uplink coverage may be caused by not only by low CPICH_RSCP But also by high UL_RSSI bull If the downlink transmission power reaches the maximum before call drop and the downlink BLER is weak the call drop is probably due to weak downlink coverage High downlink RSSI received by UE is an indication of weak coverage during that time UE tries to increase its target SIR to listen to the network Multipath propagation yields signal paths of different lengths with different times of arrival at the receiver Typical values of time delays (μs) are 02 in Open environment 05 Suburban and 3 in Urban When coded data rates of services are incompatible ldquoRate Matchingrdquo is used to equalize the data rates ndash Rate Matching may be performed by 1048707 Padding with extra bits 1048707 Puncturing of bits using a pseudo-random algorithm

Case 2 Drop due to Poor Coverage (low RSCP)

Problem Poor DL coverage

When UE gets to an area with low RSCP ( lt -105 dBm)

regardless EcNo values there is high risk for drop

UE will likely ramp up the transmitted power and reach its

max power The UL BLER will probably increase and SIR

target cannot maintain anymore finally the call drops

Explain the concept of Cell Breathing How is the accounted for in the linkBudget Ans Io or No (the interference part of EcIo and EbNo) increase as the traffic on the network increases since everyone is using the same frequency Therefore as Io or No increases the UE or BTS needs to use more power to maintain the same EbNo or EcIo When the power required is more thanthe maximum power allowed the connection cannot be made Users at the cell edge are usually the first to lose service hence the service area of a cell shrinks As traffic decreases the reverse happens and the service area increases They should say that it is accounted for in the Noise Rise Margin found in the Link Budget

Interference

In downlink when the active set CPICH RSCP is greater than ndash85 dBm and the active set EcIo is gt= ndash12 dB the call drop is probably due to downlink interference Downlink interference usually refers to pilot pollution Interference in Uplink is detected when the Uplink RTWP exceeds a certain configurable Threshold In general Expected level of RTWP is formed by sum of the the following components 1Thermal noise floor (KTB =-108132dBm) 2Node B noise figure (Typically 18 dB for our equipment) 3Noise raise due to load (50 load in Uplink corresponds to 3 db) 4Compensation for inaccuracies in Radio NW algoriths (2dB) WHAT IS THE PILOT POLLUTION Area where the SIR (Signal interference ratio) is too low and below the expected value (EcIo gt= -12 dB) there is too much interference =gt the mobile cannot understand the pilot channel HOW TO REDUCE THE PILOT POLLUTION PROBLEM Maximise the signal inside the best server Minimise the energy overshoot from the neighbor cells with some RF consideration (tilt azimuthhellip)

Pilot Pollution

Excessive strong pilots exist at a point but no one is strong enough to be primary pilot 1 Definition of strong pilot (CPICH_RSCP gt ThRSCP) 2 Definition of Excessive CPICH_Number gt ThN

3 Definition of no best server strong enoughrdquo CPICH_RSCP1st-CPICH_RSCP(ThN+1)th lt ThRSCP_Relative

Following is the case from cluster Mongkok West Probable Solution adjust engineering parameters of an antenna so that a best server forms around the antenna For handover problems caused by pilot pollution adjust engineering parameters of other antennas so that signals from other antennas becomes weaker and the number of pilots drops For this case reduce antenna height of site SGI Many definitions A cell that has a high signal strength at a location but is not part of the active set A cell that meets thecriteria for addition into the Active Set but can not enter because the active set is full

1UE fails to receive active set update command (Delayed Handover) After UE reports measurement message the EcIo of original cell signals decreases sharply When the RNC sends active set update message the UE powers off the transmitter due to asynchronization The UE cannot receive active set update message This may be due to EcIo of original cell decreases sharply and that of the target cell increases greatly (Turnings) 2 The best server changes frequently Two or more cells alternate to be the best server The RSCP of the best server is strong The period for each cell to be the best server is short Probable solution Lower the triggering time for event 1a adjust antennas to expand the handover area adjust the antenna to form a best server reduce Ping-pong handover by setting the handover parameter of 1B event

17

Radio Interface Protocol Architecture

Radio

Interface

Protocol

Architecture

Transport Channel (SAP)

Physical Channels

Logical Channel

L3

contr

ol

contr

ol

contr

ol

contr

ol

Logical

Channels

Transport

Channels

C-plane signalling U-plane information

PHY

L2MAC

L1

RLC

DCNtGC

L2RLC

MAC

RLC

RLCRLC

RLC

RLCRLC

RLC

Duplication avoidance

UuS boundary

BMC L2BMC

RRC

control

PDCPPDCP L2PDCP

DCNtGC

Packet Data Convergence Protocol

Is only for PS domain services

18

Radio Interface protocol architecture

L2MAC

L2RLC

L1

RLC

MAC

L3 RRC

PHY

Transport Channels

Logical Channels

C-plane signalling U-plane information

GC Nt DC

RLC RLC

RLC

GC NT DC RRC RLC MAC

General Control Notification Dedicated Control Radio Resource Control Radio Link Control Medium Access Control

UTRA Protocol Architecture

19

Logical Channel Structure

Synchronisation Control Channel (SCCH)

Broadcast Control Channel (BCCH)

Paging Control Channel (PCCH)

Dedicated Control Channel (DCCH)

Dedicated Control Channel (DCCH)Common Control Channel (CCCH)

Control Channel (CCH)

Dedicated Traffic Channel (DTCH)Traffic Channel (TCH)

ODMA Dedicated Control Channel (ODCCH)

ODMA Common Control Channel (OCCCH)

ODMA Dedicated Traffic Channel (ODTCH)

Common Traffic Channel (CTCH)

Shared Channel Control Channel (SHCCH)

(TDD)

(ODMA)

(ODMA)

(TDD)

20

Channels

Transport Channels Dedicated Transport Channel (DCH) ULDL mapped to DCCH and DTCH Broadcast Channel (BCH) DL mapped to BCCH Forward Access Channel (FACH) DL mapped to BCCH CCCH CTCH DCCH and DTCH Paging Channel (PCH) DL mapped to PCCH Random Access Channel (RACH) UL mapped to CCCH DCCH and DTCH Uplink Common Packet Channel (CPCH) UL mapped to DCCH and DTCH Downlink Shared Channel (DSCH) DL mapped to DCCH and DTCH The speech service in UMTS will employ the Adaptive Multi - rate technique 1048707 This is a single integrated codec with eight source rates 122 102 795 740 670 590 515 and 475 kbps To facilitate interoperability with existing cellular networks some of the modes are the same as in existing networks

21

Channels Physical Channels Primary Common Control Physical Channel (PCCPCH) mapped to BCH Secondary Common Control Physical Channel (SCCPCH) mapped to FACH PCH Physical Random Access Channel (PRACH) mapped to RACH Dedicated Physical Data Channel (DPDCH) mapped to DCH Dedicated Physical Control Channel (DPCCH) mapped to DCH Physical Downlink Shared Channel (PDSCH) mapped to DSCH Physical Common Packet Channel (PCPCH) mapped to CPCH Synchronisation Channel (SCH) Common Pilot Channel (CPICH) Acquisition Indicator Channel (AICH) Paging Indication Channel (PICH) CPCH Status Indication Channel (CSICH) Collision DetectionChannel Assignment Indication Channel (CDCA-ICH)

AMR

The bit rate of the AMR speech connection is controlled by the radio access network depending on the air interface loading and the quality of the speech connections During high loading such as during busy hours it is possible to use lower AMR bit rates to offer higher capacity while providing slightly lower speech quality Also if the mobile is running out of the cell coverage area and using its maximum transmission power a lower AMR bit rate can be used to extend the cell coverage area Adaptive multi-rate also contains error concealment The purpose of frame substitution is to conceal the effect of lost speech frames If several frames are lost muting is used to prevent possibly annoying sounds as a result of the frame substitution In P5 with AMR NB it is possible to use lower speech codec rates than 122 kbps The radio network also supports 795 kbps 59 kbps and 475 kbps AMR codecs There is no adaptation in the sense that AMR codecs are changed during an ongoing speech connection rather there is a possibility to adapt the rate at initial selection

23

Link Budget

bull Cell range amp cell capacity are limited by the same parameters

Interference in uplink

Power in downlink

bull Cell breathing phenomenon

ldquoPowerrdquo Link Budget

Tx power + All Gains ndash Path Loss ndash Other losses = Rx power

Path loss = Tx Signal + All Gains ndash Other losses ndash Rx power

Max Path loss = Tx Signal + All Gains ndash Other losses ndash Rx sensitivity

25

Initial Cell Search

The initial Cell Search is carried out in three steps

Step 1 Slot synchronisation - using the primary synchronisation channel

Step 2 Frame synchronisation and code-group identification- using the secondary synchronisation channel

Step 3 Scrambling-code identification-identified through symbol- by-symbol correlation over the primary CCPCH with all the scrambling codes within the code group

26

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

27

Frame Synchronization

helliphellip

2560 chips

acp

Slot

P-SCH acp

Slot

16 11 S-SCH

acp

Slot

2 Group 4 Slot 121314

slot number Scrambling Code Group 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Group 0 1 1 2 8 9 10 15 8 10 16 2 7 15 7 16

Group 1 1 1 5 16 7 3 14 16 3 10 5 12 14 12 10

Group 2 1 2 1 15 5 5 12 16 6 11 2 16 11 15 12

Group 3 1 2 3 1 8 6 5 2 5 8 4 4 6 3 7

Group 4 1 2 16 6 6 11 15 5 12 1 15 12 16 11 2

hellip

Group 61 9 10 13 10 11 15 15 9 16 12 14 13 16 14 11

Group 62 9 11 12 15 12 9 13 13 11 14 10 16 15 14 16

Group 63 9 12 10 15 13 14 9 14 15 11 11 13 12 16 10

256 chips

S-SCH

P-SCH

512 Primary Scrambling Codes divided into 64 groups

28

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

29

Cell Information

P-SCH Coverage indication Slot Synchronization

S-SCH Frame Synchronization Group identification

P-CPICH Scrambling Code Identification

P-CCPCH System Information Broadcast

Logical Channel

BCCH

Transport Channel

BCH

Physical Channel

P-CCPCH

OVSF Cch2561

Primary Scrambling Code

Transmitted during 910th slot

Bit Rate 123 kbps RLC Mode transparent

Mac-B transparent

30

Intra-Frequency Cell Reselection sample

Time

Quality

Serving CellServing Cell

Neighboring Cell

Neighboring Cell

Neighboring

cell criterion S

is fulfilled and is

ranked

Neighboring cell

better ranking

than Serving cell

UE perform cell

reselection

Treselections

Qmeans + Qhyst2s

Qmeann - Qoffset2sn

Qqualmin

UE perform

intra-frequency

measurements

Qqualmin +

SIntraSearch

31

Cell selection and reselection Cell Selection criteria

The cell selection criterion S is fulfilled when

where

Squal = Qqualmeas ndash Qqualmin

Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

Pcompensation ＝ max(UE_TXPWR_MAX_RACH ndash P_MAX 0)

for FDD cells Srxlev gt 0 AND Squal gt 0

for TDD cells Srxlev gt 0

for GSM cells Srxlev gt 0

32

Cell Selection Parameters

Parameter Object Range Default Value Recommended Value Class

qQualMin CellSelectionInfo Int [-240]

(dB)

-10 -16 C2

qRxLevMin CellSelectionInfo Int [-115-25]

Step = 2 (dBm)

-45 -115 C2

maxAllowedUlTxPower UlUsPowerConf Int [-5033]

(dBm)

33 33 C3

P_Max = maximum UE output power (dBm) according to its class

Power Class Maximum Output Power (dBm)

1 33

2 27

3 24

4 21

33

Cell Reselection Procedure

Squal

SintraSearch

SinterSearch

SinterRAT Measurement on

same frequency Measurement on

other frequencies Measurement on

other RAT

If Squal = CPICH_EcNo ndash qQualMin lt Threshold

Associated measurements are performed

Thresholds are broadcasted in SIB 11

In UMTS02 2 types of measurements are done Intra frequency and inter RAT

Th

rese

ho

lds

giv

en a

s ex

am

ple

34

Cell Reselection Parameters

Parameter Object Range Default Value Recommended Value Class

qHyst1 CellSelectionInfo Int [040] (dBm)

Step = 2

10 4 C2

qHyst2 CellSelectionInfo

Int [040] (dB)

Step = 2

4 6 C2

qOffset1sn GSMCell

Int [-5050] (dB) 0 TBD C0

qOffset2sn UMTSFDDNeighbouring Int [-5050] (dB) 0 TBD C0

qualMeas CPICH_EcNo or

CPICH_RSCP

CPICH_EcNo NA Static

tReselection CellSelectionInfo Int [031] (s) 31 6 C2

35

Measurements

The different types of air interface measurements are

bull Intra-frequency measurements measurements on downlink physical channels at the same frequency as the active set A measurement object corresponds to one cell

bull Inter-frequency measurements measurements on downlink physical channels at frequencies that differ from the frequency of the active set A measurement object corresponds to one cell

bull Inter-RAT measurements measurements on downlink physical channels belonging to another radio access technology than UTRAN eg GSM A measurement object corresponds to one cell

36

Handover (Handoff) bull There are following categories of handover (also referred to as handoff)

bull Hard handover means that all the old radio links in the UE are removed before

the new radio links are established Hard handover can be seamless or non-seamless Seamless hard handover means that the handover is not perceptible to the user In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover

bull Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN Soft handover is performed by means of macro diversity which refers to the condition that several radio links are active at the same time

bull Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (ie the site of co-located base stations from which several sector-cells are served

37

Handover (Handoff) bull The most obvious cause for performing a handover is that due to its movement a user

can be served in another cell more efficiently (like less power emission less interference) It may however also be performed for other reasons such as system load control

bull Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (ie the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set)

bull The maximum active set size at the RNC is determined by the parameter MaxAciveSetSize

bull 3 to 4 cells the larger the active set size the more likely it is that Iub link efficiency is reduced (more than one resource for a single connection due to SHO)

bull Cells which are not included in the active set but are included in the CELL_INFO_LIST belong to the Monitored Set

bull Cells detected by the UE which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state

38

PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)

bull The primary cell election algorithm applies to soft HO It is used for monitored set determination and a pointer to mobility parameter

bull The Monitored Set should be updated each time the primary cell of active set changes A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set The message contains the cell to addremove from the monitored and should follow the ACIVE SET UPDATE message

bull The primary cell algorithm is called from SHO algorithm therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC

Measurement control used for monitored set update

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

KEY PERFORMANCE INDICATORS

Accessability (Call set-up success rate)

Retainability (Dropped calls)

Mobility (Handover success rate)

Integrity (BLER and throughput)

Integrity- quality

Integrity-throughput

What is the major difference in link budgets between UMTS and GSMTDMA In UMTS you generally have a link budget for each service (voice data video etc) in GSM you usually only use 1 for voice Each service has a different EbNo target In UMTS you have to consider the target traffic load you will have and add a noise-rise margin in GSM you may have a slight interference margin but not normally related to traffic In UMTS some services (like voice) will show up as uplink limited but other services (like HSDPA 384kbps service) will show as downlink limited In UMTS you usually have to consider that all users use the same power from the BTS therefore the more number of users the lower the maximumpower available per user (maximum power per connection) which is a starting point in the link budget

KPI Requirements Formula

CPICH RSCP ge-95dBm NA (nbr_of_samples_RSCPgt=-95dBm)

(tot_nbr_of_samples_RSCP)

CPICH EcIo ge-12dB NA (nbr_of_samples_EcIogt=-12dB)

(tot_nbr_of_samples_EcIo)

Voice call setup

success rate Min ge98

(nbr_of_successful_voice_call_setup)

(nbr_of_voice_call_attemp)

Voice call setup time

(Mobile to 1764440)

le10s ge99

(nbr_of_voice_call_setup_timele10s)

(nbr_of_successful_voice_call_setup)

voice_call_setup_time =[T(CC_alerting) - T(first_RRC_connection_request)]

le9s ge95

(nbr_of_voice_call_setup_timele9s)

(nbr_of_successful_voice_call_setup)

voice_call_setup_time =[T(CC_alerting) - T(first_RRC_connection_request)]

Voice call drop rate Max le2 (nbr_of_voice_call_drop)

[(call_duration_time)90sec]

PDP activation

successful rate Min ge99

(nbr_of_PDP_context_activation_accept)

(nbr_of_PDP_context_activation_request)

PDP activation delay le2s ge99

(nbr_of_PDP_activation_delayle2s)

(nbr_of_PDP_context_activation_accept)

PDP_activation_delay= [T(PDP_context_activation_accept)-

T(PDP_context_activation_request)]

PS 384k FTP DL Avg Throughput 280kbps (downloaded_data_kbit)

(data_session_duration)

PS 384k FTP UL Avg Throughput 280kbps (uploaded_data_kbit)

(data_session_duration)

HSDPA FTP Avg Throughput 45Mbps (downloaded_data_kbit)

(data_session_duration)

HSUPA FTP Avg Throughput 11Mbps (uploaded_data_kbit)

(data_session_duration)

KPI calculation

Case 1 Drop due to missing neighbor

Problem Detected Nighbor (DN)

bull UE sends a Measurement Report that contains an event1a means adding a new RL (cell) to Active Set

bull If the reported cell is not in the current neighbor cell list and the reported EcNo is better than the best serving cell EcNo in AS by some dBs (set by a RNC parameter)

bull If for any reason the new cell can not be added to AS call will be released

2 If the UE reconnects to the network immediately after call drop and the scramble of the cell that UE camps on is different from that upon call drop missing neighbor cell is probable Confirm it by measurement control (search the messages back from call drop for the latest intra-frequency measurement control message Check the neighbor cell list of this measurement control message)

3 UEs might report detected set information If corresponding scramblling code information is in the monitor set before call drop the cause must be missing neighbor cell

Weak Coverage

bull Weak coverage usually refers to weak RSCP Uplink or downlink DCH power helps to confirm the weak coverage is in uplink or downlink by the following methods bull If the uplink transmission power reaches the maximum before call drop the uplink BLER is weak the call drop is probably due to weak uplink coverage bull Out of Uplink coverage may be caused by not only by low CPICH_RSCP But also by high UL_RSSI bull If the downlink transmission power reaches the maximum before call drop and the downlink BLER is weak the call drop is probably due to weak downlink coverage High downlink RSSI received by UE is an indication of weak coverage during that time UE tries to increase its target SIR to listen to the network Multipath propagation yields signal paths of different lengths with different times of arrival at the receiver Typical values of time delays (μs) are 02 in Open environment 05 Suburban and 3 in Urban When coded data rates of services are incompatible ldquoRate Matchingrdquo is used to equalize the data rates ndash Rate Matching may be performed by 1048707 Padding with extra bits 1048707 Puncturing of bits using a pseudo-random algorithm

Case 2 Drop due to Poor Coverage (low RSCP)

Problem Poor DL coverage

When UE gets to an area with low RSCP ( lt -105 dBm)

regardless EcNo values there is high risk for drop

UE will likely ramp up the transmitted power and reach its

max power The UL BLER will probably increase and SIR

target cannot maintain anymore finally the call drops

Explain the concept of Cell Breathing How is the accounted for in the linkBudget Ans Io or No (the interference part of EcIo and EbNo) increase as the traffic on the network increases since everyone is using the same frequency Therefore as Io or No increases the UE or BTS needs to use more power to maintain the same EbNo or EcIo When the power required is more thanthe maximum power allowed the connection cannot be made Users at the cell edge are usually the first to lose service hence the service area of a cell shrinks As traffic decreases the reverse happens and the service area increases They should say that it is accounted for in the Noise Rise Margin found in the Link Budget

Interference

In downlink when the active set CPICH RSCP is greater than ndash85 dBm and the active set EcIo is gt= ndash12 dB the call drop is probably due to downlink interference Downlink interference usually refers to pilot pollution Interference in Uplink is detected when the Uplink RTWP exceeds a certain configurable Threshold In general Expected level of RTWP is formed by sum of the the following components 1Thermal noise floor (KTB =-108132dBm) 2Node B noise figure (Typically 18 dB for our equipment) 3Noise raise due to load (50 load in Uplink corresponds to 3 db) 4Compensation for inaccuracies in Radio NW algoriths (2dB) WHAT IS THE PILOT POLLUTION Area where the SIR (Signal interference ratio) is too low and below the expected value (EcIo gt= -12 dB) there is too much interference =gt the mobile cannot understand the pilot channel HOW TO REDUCE THE PILOT POLLUTION PROBLEM Maximise the signal inside the best server Minimise the energy overshoot from the neighbor cells with some RF consideration (tilt azimuthhellip)

Pilot Pollution

Excessive strong pilots exist at a point but no one is strong enough to be primary pilot 1 Definition of strong pilot (CPICH_RSCP gt ThRSCP) 2 Definition of Excessive CPICH_Number gt ThN

3 Definition of no best server strong enoughrdquo CPICH_RSCP1st-CPICH_RSCP(ThN+1)th lt ThRSCP_Relative

Following is the case from cluster Mongkok West Probable Solution adjust engineering parameters of an antenna so that a best server forms around the antenna For handover problems caused by pilot pollution adjust engineering parameters of other antennas so that signals from other antennas becomes weaker and the number of pilots drops For this case reduce antenna height of site SGI Many definitions A cell that has a high signal strength at a location but is not part of the active set A cell that meets thecriteria for addition into the Active Set but can not enter because the active set is full

1UE fails to receive active set update command (Delayed Handover) After UE reports measurement message the EcIo of original cell signals decreases sharply When the RNC sends active set update message the UE powers off the transmitter due to asynchronization The UE cannot receive active set update message This may be due to EcIo of original cell decreases sharply and that of the target cell increases greatly (Turnings) 2 The best server changes frequently Two or more cells alternate to be the best server The RSCP of the best server is strong The period for each cell to be the best server is short Probable solution Lower the triggering time for event 1a adjust antennas to expand the handover area adjust the antenna to form a best server reduce Ping-pong handover by setting the handover parameter of 1B event

17

Radio Interface Protocol Architecture

Radio

Interface

Protocol

Architecture

Transport Channel (SAP)

Physical Channels

Logical Channel

L3

contr

ol

contr

ol

contr

ol

contr

ol

Logical

Channels

Transport

Channels

C-plane signalling U-plane information

PHY

L2MAC

L1

RLC

DCNtGC

L2RLC

MAC

RLC

RLCRLC

RLC

RLCRLC

RLC

Duplication avoidance

UuS boundary

BMC L2BMC

RRC

control

PDCPPDCP L2PDCP

DCNtGC

Packet Data Convergence Protocol

Is only for PS domain services

18

Radio Interface protocol architecture

L2MAC

L2RLC

L1

RLC

MAC

L3 RRC

PHY

Transport Channels

Logical Channels

C-plane signalling U-plane information

GC Nt DC

RLC RLC

RLC

GC NT DC RRC RLC MAC

General Control Notification Dedicated Control Radio Resource Control Radio Link Control Medium Access Control

UTRA Protocol Architecture

19

Logical Channel Structure

Synchronisation Control Channel (SCCH)

Broadcast Control Channel (BCCH)

Paging Control Channel (PCCH)

Dedicated Control Channel (DCCH)

Dedicated Control Channel (DCCH)Common Control Channel (CCCH)

Control Channel (CCH)

Dedicated Traffic Channel (DTCH)Traffic Channel (TCH)

ODMA Dedicated Control Channel (ODCCH)

ODMA Common Control Channel (OCCCH)

ODMA Dedicated Traffic Channel (ODTCH)

Common Traffic Channel (CTCH)

Shared Channel Control Channel (SHCCH)

(TDD)

(ODMA)

(ODMA)

(TDD)

20

Channels

Transport Channels Dedicated Transport Channel (DCH) ULDL mapped to DCCH and DTCH Broadcast Channel (BCH) DL mapped to BCCH Forward Access Channel (FACH) DL mapped to BCCH CCCH CTCH DCCH and DTCH Paging Channel (PCH) DL mapped to PCCH Random Access Channel (RACH) UL mapped to CCCH DCCH and DTCH Uplink Common Packet Channel (CPCH) UL mapped to DCCH and DTCH Downlink Shared Channel (DSCH) DL mapped to DCCH and DTCH The speech service in UMTS will employ the Adaptive Multi - rate technique 1048707 This is a single integrated codec with eight source rates 122 102 795 740 670 590 515 and 475 kbps To facilitate interoperability with existing cellular networks some of the modes are the same as in existing networks

21

Channels Physical Channels Primary Common Control Physical Channel (PCCPCH) mapped to BCH Secondary Common Control Physical Channel (SCCPCH) mapped to FACH PCH Physical Random Access Channel (PRACH) mapped to RACH Dedicated Physical Data Channel (DPDCH) mapped to DCH Dedicated Physical Control Channel (DPCCH) mapped to DCH Physical Downlink Shared Channel (PDSCH) mapped to DSCH Physical Common Packet Channel (PCPCH) mapped to CPCH Synchronisation Channel (SCH) Common Pilot Channel (CPICH) Acquisition Indicator Channel (AICH) Paging Indication Channel (PICH) CPCH Status Indication Channel (CSICH) Collision DetectionChannel Assignment Indication Channel (CDCA-ICH)

AMR

The bit rate of the AMR speech connection is controlled by the radio access network depending on the air interface loading and the quality of the speech connections During high loading such as during busy hours it is possible to use lower AMR bit rates to offer higher capacity while providing slightly lower speech quality Also if the mobile is running out of the cell coverage area and using its maximum transmission power a lower AMR bit rate can be used to extend the cell coverage area Adaptive multi-rate also contains error concealment The purpose of frame substitution is to conceal the effect of lost speech frames If several frames are lost muting is used to prevent possibly annoying sounds as a result of the frame substitution In P5 with AMR NB it is possible to use lower speech codec rates than 122 kbps The radio network also supports 795 kbps 59 kbps and 475 kbps AMR codecs There is no adaptation in the sense that AMR codecs are changed during an ongoing speech connection rather there is a possibility to adapt the rate at initial selection

23

Link Budget

bull Cell range amp cell capacity are limited by the same parameters

Interference in uplink

Power in downlink

bull Cell breathing phenomenon

ldquoPowerrdquo Link Budget

Tx power + All Gains ndash Path Loss ndash Other losses = Rx power

Path loss = Tx Signal + All Gains ndash Other losses ndash Rx power

Max Path loss = Tx Signal + All Gains ndash Other losses ndash Rx sensitivity

25

Initial Cell Search

The initial Cell Search is carried out in three steps

Step 1 Slot synchronisation - using the primary synchronisation channel

Step 2 Frame synchronisation and code-group identification- using the secondary synchronisation channel

Step 3 Scrambling-code identification-identified through symbol- by-symbol correlation over the primary CCPCH with all the scrambling codes within the code group

26

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

27

Frame Synchronization

helliphellip

2560 chips

acp

Slot

P-SCH acp

Slot

16 11 S-SCH

acp

Slot

2 Group 4 Slot 121314

slot number Scrambling Code Group 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Group 0 1 1 2 8 9 10 15 8 10 16 2 7 15 7 16

Group 1 1 1 5 16 7 3 14 16 3 10 5 12 14 12 10

Group 2 1 2 1 15 5 5 12 16 6 11 2 16 11 15 12

Group 3 1 2 3 1 8 6 5 2 5 8 4 4 6 3 7

Group 4 1 2 16 6 6 11 15 5 12 1 15 12 16 11 2

hellip

Group 61 9 10 13 10 11 15 15 9 16 12 14 13 16 14 11

Group 62 9 11 12 15 12 9 13 13 11 14 10 16 15 14 16

Group 63 9 12 10 15 13 14 9 14 15 11 11 13 12 16 10

256 chips

S-SCH

P-SCH

512 Primary Scrambling Codes divided into 64 groups

28

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

29

Cell Information

P-SCH Coverage indication Slot Synchronization

S-SCH Frame Synchronization Group identification

P-CPICH Scrambling Code Identification

P-CCPCH System Information Broadcast

Logical Channel

BCCH

Transport Channel

BCH

Physical Channel

P-CCPCH

OVSF Cch2561

Primary Scrambling Code

Transmitted during 910th slot

Bit Rate 123 kbps RLC Mode transparent

Mac-B transparent

30

Intra-Frequency Cell Reselection sample

Time

Quality

Serving CellServing Cell

Neighboring Cell

Neighboring Cell

Neighboring

cell criterion S

is fulfilled and is

ranked

Neighboring cell

better ranking

than Serving cell

UE perform cell

reselection

Treselections

Qmeans + Qhyst2s

Qmeann - Qoffset2sn

Qqualmin

UE perform

intra-frequency

measurements

Qqualmin +

SIntraSearch

31

Cell selection and reselection Cell Selection criteria

The cell selection criterion S is fulfilled when

where

Squal = Qqualmeas ndash Qqualmin

Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

Pcompensation ＝ max(UE_TXPWR_MAX_RACH ndash P_MAX 0)

for FDD cells Srxlev gt 0 AND Squal gt 0

for TDD cells Srxlev gt 0

for GSM cells Srxlev gt 0

32

Cell Selection Parameters

Parameter Object Range Default Value Recommended Value Class

qQualMin CellSelectionInfo Int [-240]

(dB)

-10 -16 C2

qRxLevMin CellSelectionInfo Int [-115-25]

Step = 2 (dBm)

-45 -115 C2

maxAllowedUlTxPower UlUsPowerConf Int [-5033]

(dBm)

33 33 C3

P_Max = maximum UE output power (dBm) according to its class

Power Class Maximum Output Power (dBm)

1 33

2 27

3 24

4 21

33

Cell Reselection Procedure

Squal

SintraSearch

SinterSearch

SinterRAT Measurement on

same frequency Measurement on

other frequencies Measurement on

other RAT

If Squal = CPICH_EcNo ndash qQualMin lt Threshold

Associated measurements are performed

Thresholds are broadcasted in SIB 11

In UMTS02 2 types of measurements are done Intra frequency and inter RAT

Th

rese

ho

lds

giv

en a

s ex

am

ple

34

Cell Reselection Parameters

Parameter Object Range Default Value Recommended Value Class

qHyst1 CellSelectionInfo Int [040] (dBm)

Step = 2

10 4 C2

qHyst2 CellSelectionInfo

Int [040] (dB)

Step = 2

4 6 C2

qOffset1sn GSMCell

Int [-5050] (dB) 0 TBD C0

qOffset2sn UMTSFDDNeighbouring Int [-5050] (dB) 0 TBD C0

qualMeas CPICH_EcNo or

CPICH_RSCP

CPICH_EcNo NA Static

tReselection CellSelectionInfo Int [031] (s) 31 6 C2

35

Measurements

The different types of air interface measurements are

bull Intra-frequency measurements measurements on downlink physical channels at the same frequency as the active set A measurement object corresponds to one cell

bull Inter-frequency measurements measurements on downlink physical channels at frequencies that differ from the frequency of the active set A measurement object corresponds to one cell

bull Inter-RAT measurements measurements on downlink physical channels belonging to another radio access technology than UTRAN eg GSM A measurement object corresponds to one cell

36

Handover (Handoff) bull There are following categories of handover (also referred to as handoff)

bull Hard handover means that all the old radio links in the UE are removed before

the new radio links are established Hard handover can be seamless or non-seamless Seamless hard handover means that the handover is not perceptible to the user In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover

bull Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN Soft handover is performed by means of macro diversity which refers to the condition that several radio links are active at the same time

bull Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (ie the site of co-located base stations from which several sector-cells are served

37

Handover (Handoff) bull The most obvious cause for performing a handover is that due to its movement a user

can be served in another cell more efficiently (like less power emission less interference) It may however also be performed for other reasons such as system load control

bull Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (ie the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set)

bull The maximum active set size at the RNC is determined by the parameter MaxAciveSetSize

bull 3 to 4 cells the larger the active set size the more likely it is that Iub link efficiency is reduced (more than one resource for a single connection due to SHO)

bull Cells which are not included in the active set but are included in the CELL_INFO_LIST belong to the Monitored Set

bull Cells detected by the UE which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state

38

PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)

bull The primary cell election algorithm applies to soft HO It is used for monitored set determination and a pointer to mobility parameter

bull The Monitored Set should be updated each time the primary cell of active set changes A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set The message contains the cell to addremove from the monitored and should follow the ACIVE SET UPDATE message

bull The primary cell algorithm is called from SHO algorithm therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC

Measurement control used for monitored set update

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

KPI Requirements Formula

CPICH RSCP ge-95dBm NA (nbr_of_samples_RSCPgt=-95dBm)

(tot_nbr_of_samples_RSCP)

CPICH EcIo ge-12dB NA (nbr_of_samples_EcIogt=-12dB)

(tot_nbr_of_samples_EcIo)

Voice call setup

success rate Min ge98

(nbr_of_successful_voice_call_setup)

(nbr_of_voice_call_attemp)

Voice call setup time

(Mobile to 1764440)

le10s ge99

(nbr_of_voice_call_setup_timele10s)

(nbr_of_successful_voice_call_setup)

voice_call_setup_time =[T(CC_alerting) - T(first_RRC_connection_request)]

le9s ge95

(nbr_of_voice_call_setup_timele9s)

(nbr_of_successful_voice_call_setup)

voice_call_setup_time =[T(CC_alerting) - T(first_RRC_connection_request)]

Voice call drop rate Max le2 (nbr_of_voice_call_drop)

[(call_duration_time)90sec]

PDP activation

successful rate Min ge99

(nbr_of_PDP_context_activation_accept)

(nbr_of_PDP_context_activation_request)

PDP activation delay le2s ge99

(nbr_of_PDP_activation_delayle2s)

(nbr_of_PDP_context_activation_accept)

PDP_activation_delay= [T(PDP_context_activation_accept)-

T(PDP_context_activation_request)]

PS 384k FTP DL Avg Throughput 280kbps (downloaded_data_kbit)

(data_session_duration)

PS 384k FTP UL Avg Throughput 280kbps (uploaded_data_kbit)

(data_session_duration)

HSDPA FTP Avg Throughput 45Mbps (downloaded_data_kbit)

(data_session_duration)

HSUPA FTP Avg Throughput 11Mbps (uploaded_data_kbit)

(data_session_duration)

KPI calculation

Case 1 Drop due to missing neighbor

Problem Detected Nighbor (DN)

bull UE sends a Measurement Report that contains an event1a means adding a new RL (cell) to Active Set

bull If the reported cell is not in the current neighbor cell list and the reported EcNo is better than the best serving cell EcNo in AS by some dBs (set by a RNC parameter)

bull If for any reason the new cell can not be added to AS call will be released

2 If the UE reconnects to the network immediately after call drop and the scramble of the cell that UE camps on is different from that upon call drop missing neighbor cell is probable Confirm it by measurement control (search the messages back from call drop for the latest intra-frequency measurement control message Check the neighbor cell list of this measurement control message)

3 UEs might report detected set information If corresponding scramblling code information is in the monitor set before call drop the cause must be missing neighbor cell

Weak Coverage

bull Weak coverage usually refers to weak RSCP Uplink or downlink DCH power helps to confirm the weak coverage is in uplink or downlink by the following methods bull If the uplink transmission power reaches the maximum before call drop the uplink BLER is weak the call drop is probably due to weak uplink coverage bull Out of Uplink coverage may be caused by not only by low CPICH_RSCP But also by high UL_RSSI bull If the downlink transmission power reaches the maximum before call drop and the downlink BLER is weak the call drop is probably due to weak downlink coverage High downlink RSSI received by UE is an indication of weak coverage during that time UE tries to increase its target SIR to listen to the network Multipath propagation yields signal paths of different lengths with different times of arrival at the receiver Typical values of time delays (μs) are 02 in Open environment 05 Suburban and 3 in Urban When coded data rates of services are incompatible ldquoRate Matchingrdquo is used to equalize the data rates ndash Rate Matching may be performed by 1048707 Padding with extra bits 1048707 Puncturing of bits using a pseudo-random algorithm

Case 2 Drop due to Poor Coverage (low RSCP)

Problem Poor DL coverage

When UE gets to an area with low RSCP ( lt -105 dBm)

regardless EcNo values there is high risk for drop

UE will likely ramp up the transmitted power and reach its

max power The UL BLER will probably increase and SIR

target cannot maintain anymore finally the call drops

Explain the concept of Cell Breathing How is the accounted for in the linkBudget Ans Io or No (the interference part of EcIo and EbNo) increase as the traffic on the network increases since everyone is using the same frequency Therefore as Io or No increases the UE or BTS needs to use more power to maintain the same EbNo or EcIo When the power required is more thanthe maximum power allowed the connection cannot be made Users at the cell edge are usually the first to lose service hence the service area of a cell shrinks As traffic decreases the reverse happens and the service area increases They should say that it is accounted for in the Noise Rise Margin found in the Link Budget

Interference

In downlink when the active set CPICH RSCP is greater than ndash85 dBm and the active set EcIo is gt= ndash12 dB the call drop is probably due to downlink interference Downlink interference usually refers to pilot pollution Interference in Uplink is detected when the Uplink RTWP exceeds a certain configurable Threshold In general Expected level of RTWP is formed by sum of the the following components 1Thermal noise floor (KTB =-108132dBm) 2Node B noise figure (Typically 18 dB for our equipment) 3Noise raise due to load (50 load in Uplink corresponds to 3 db) 4Compensation for inaccuracies in Radio NW algoriths (2dB) WHAT IS THE PILOT POLLUTION Area where the SIR (Signal interference ratio) is too low and below the expected value (EcIo gt= -12 dB) there is too much interference =gt the mobile cannot understand the pilot channel HOW TO REDUCE THE PILOT POLLUTION PROBLEM Maximise the signal inside the best server Minimise the energy overshoot from the neighbor cells with some RF consideration (tilt azimuthhellip)

Pilot Pollution

Excessive strong pilots exist at a point but no one is strong enough to be primary pilot 1 Definition of strong pilot (CPICH_RSCP gt ThRSCP) 2 Definition of Excessive CPICH_Number gt ThN

3 Definition of no best server strong enoughrdquo CPICH_RSCP1st-CPICH_RSCP(ThN+1)th lt ThRSCP_Relative

Following is the case from cluster Mongkok West Probable Solution adjust engineering parameters of an antenna so that a best server forms around the antenna For handover problems caused by pilot pollution adjust engineering parameters of other antennas so that signals from other antennas becomes weaker and the number of pilots drops For this case reduce antenna height of site SGI Many definitions A cell that has a high signal strength at a location but is not part of the active set A cell that meets thecriteria for addition into the Active Set but can not enter because the active set is full

1UE fails to receive active set update command (Delayed Handover) After UE reports measurement message the EcIo of original cell signals decreases sharply When the RNC sends active set update message the UE powers off the transmitter due to asynchronization The UE cannot receive active set update message This may be due to EcIo of original cell decreases sharply and that of the target cell increases greatly (Turnings) 2 The best server changes frequently Two or more cells alternate to be the best server The RSCP of the best server is strong The period for each cell to be the best server is short Probable solution Lower the triggering time for event 1a adjust antennas to expand the handover area adjust the antenna to form a best server reduce Ping-pong handover by setting the handover parameter of 1B event

17

Radio Interface Protocol Architecture

Radio

Interface

Protocol

Architecture

Transport Channel (SAP)

Physical Channels

Logical Channel

L3

contr

ol

contr

ol

contr

ol

contr

ol

Logical

Channels

Transport

Channels

C-plane signalling U-plane information

PHY

L2MAC

L1

RLC

DCNtGC

L2RLC

MAC

RLC

RLCRLC

RLC

RLCRLC

RLC

Duplication avoidance

UuS boundary

BMC L2BMC

RRC

control

PDCPPDCP L2PDCP

DCNtGC

Packet Data Convergence Protocol

Is only for PS domain services

18

Radio Interface protocol architecture

L2MAC

L2RLC

L1

RLC

MAC

L3 RRC

PHY

Transport Channels

Logical Channels

C-plane signalling U-plane information

GC Nt DC

RLC RLC

RLC

GC NT DC RRC RLC MAC

General Control Notification Dedicated Control Radio Resource Control Radio Link Control Medium Access Control

UTRA Protocol Architecture

19

Logical Channel Structure

Synchronisation Control Channel (SCCH)

Broadcast Control Channel (BCCH)

Paging Control Channel (PCCH)

Dedicated Control Channel (DCCH)

Dedicated Control Channel (DCCH)Common Control Channel (CCCH)

Control Channel (CCH)

Dedicated Traffic Channel (DTCH)Traffic Channel (TCH)

ODMA Dedicated Control Channel (ODCCH)

ODMA Common Control Channel (OCCCH)

ODMA Dedicated Traffic Channel (ODTCH)

Common Traffic Channel (CTCH)

Shared Channel Control Channel (SHCCH)

(TDD)

(ODMA)

(ODMA)

(TDD)

20

Channels

Transport Channels Dedicated Transport Channel (DCH) ULDL mapped to DCCH and DTCH Broadcast Channel (BCH) DL mapped to BCCH Forward Access Channel (FACH) DL mapped to BCCH CCCH CTCH DCCH and DTCH Paging Channel (PCH) DL mapped to PCCH Random Access Channel (RACH) UL mapped to CCCH DCCH and DTCH Uplink Common Packet Channel (CPCH) UL mapped to DCCH and DTCH Downlink Shared Channel (DSCH) DL mapped to DCCH and DTCH The speech service in UMTS will employ the Adaptive Multi - rate technique 1048707 This is a single integrated codec with eight source rates 122 102 795 740 670 590 515 and 475 kbps To facilitate interoperability with existing cellular networks some of the modes are the same as in existing networks

21

Channels Physical Channels Primary Common Control Physical Channel (PCCPCH) mapped to BCH Secondary Common Control Physical Channel (SCCPCH) mapped to FACH PCH Physical Random Access Channel (PRACH) mapped to RACH Dedicated Physical Data Channel (DPDCH) mapped to DCH Dedicated Physical Control Channel (DPCCH) mapped to DCH Physical Downlink Shared Channel (PDSCH) mapped to DSCH Physical Common Packet Channel (PCPCH) mapped to CPCH Synchronisation Channel (SCH) Common Pilot Channel (CPICH) Acquisition Indicator Channel (AICH) Paging Indication Channel (PICH) CPCH Status Indication Channel (CSICH) Collision DetectionChannel Assignment Indication Channel (CDCA-ICH)

AMR

The bit rate of the AMR speech connection is controlled by the radio access network depending on the air interface loading and the quality of the speech connections During high loading such as during busy hours it is possible to use lower AMR bit rates to offer higher capacity while providing slightly lower speech quality Also if the mobile is running out of the cell coverage area and using its maximum transmission power a lower AMR bit rate can be used to extend the cell coverage area Adaptive multi-rate also contains error concealment The purpose of frame substitution is to conceal the effect of lost speech frames If several frames are lost muting is used to prevent possibly annoying sounds as a result of the frame substitution In P5 with AMR NB it is possible to use lower speech codec rates than 122 kbps The radio network also supports 795 kbps 59 kbps and 475 kbps AMR codecs There is no adaptation in the sense that AMR codecs are changed during an ongoing speech connection rather there is a possibility to adapt the rate at initial selection

23

Link Budget

bull Cell range amp cell capacity are limited by the same parameters

Interference in uplink

Power in downlink

bull Cell breathing phenomenon

ldquoPowerrdquo Link Budget

Tx power + All Gains ndash Path Loss ndash Other losses = Rx power

Path loss = Tx Signal + All Gains ndash Other losses ndash Rx power

Max Path loss = Tx Signal + All Gains ndash Other losses ndash Rx sensitivity

25

Initial Cell Search

The initial Cell Search is carried out in three steps

Step 1 Slot synchronisation - using the primary synchronisation channel

Step 2 Frame synchronisation and code-group identification- using the secondary synchronisation channel

Step 3 Scrambling-code identification-identified through symbol- by-symbol correlation over the primary CCPCH with all the scrambling codes within the code group

26

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

27

Frame Synchronization

helliphellip

2560 chips

acp

Slot

P-SCH acp

Slot

16 11 S-SCH

acp

Slot

2 Group 4 Slot 121314

slot number Scrambling Code Group 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Group 0 1 1 2 8 9 10 15 8 10 16 2 7 15 7 16

Group 1 1 1 5 16 7 3 14 16 3 10 5 12 14 12 10

Group 2 1 2 1 15 5 5 12 16 6 11 2 16 11 15 12

Group 3 1 2 3 1 8 6 5 2 5 8 4 4 6 3 7

Group 4 1 2 16 6 6 11 15 5 12 1 15 12 16 11 2

hellip

Group 61 9 10 13 10 11 15 15 9 16 12 14 13 16 14 11

Group 62 9 11 12 15 12 9 13 13 11 14 10 16 15 14 16

Group 63 9 12 10 15 13 14 9 14 15 11 11 13 12 16 10

256 chips

S-SCH

P-SCH

512 Primary Scrambling Codes divided into 64 groups

28

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

29

Cell Information

P-SCH Coverage indication Slot Synchronization

S-SCH Frame Synchronization Group identification

P-CPICH Scrambling Code Identification

P-CCPCH System Information Broadcast

Logical Channel

BCCH

Transport Channel

BCH

Physical Channel

P-CCPCH

OVSF Cch2561

Primary Scrambling Code

Transmitted during 910th slot

Bit Rate 123 kbps RLC Mode transparent

Mac-B transparent

30

Intra-Frequency Cell Reselection sample

Time

Quality

Serving CellServing Cell

Neighboring Cell

Neighboring Cell

Neighboring

cell criterion S

is fulfilled and is

ranked

Neighboring cell

better ranking

than Serving cell

UE perform cell

reselection

Treselections

Qmeans + Qhyst2s

Qmeann - Qoffset2sn

Qqualmin

UE perform

intra-frequency

measurements

Qqualmin +

SIntraSearch

31

Cell selection and reselection Cell Selection criteria

The cell selection criterion S is fulfilled when

where

Squal = Qqualmeas ndash Qqualmin

Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

Pcompensation ＝ max(UE_TXPWR_MAX_RACH ndash P_MAX 0)

for FDD cells Srxlev gt 0 AND Squal gt 0

for TDD cells Srxlev gt 0

for GSM cells Srxlev gt 0

32

Cell Selection Parameters

Parameter Object Range Default Value Recommended Value Class

qQualMin CellSelectionInfo Int [-240]

(dB)

-10 -16 C2

qRxLevMin CellSelectionInfo Int [-115-25]

Step = 2 (dBm)

-45 -115 C2

maxAllowedUlTxPower UlUsPowerConf Int [-5033]

(dBm)

33 33 C3

P_Max = maximum UE output power (dBm) according to its class

Power Class Maximum Output Power (dBm)

1 33

2 27

3 24

4 21

33

Cell Reselection Procedure

Squal

SintraSearch

SinterSearch

SinterRAT Measurement on

same frequency Measurement on

other frequencies Measurement on

other RAT

If Squal = CPICH_EcNo ndash qQualMin lt Threshold

Associated measurements are performed

Thresholds are broadcasted in SIB 11

In UMTS02 2 types of measurements are done Intra frequency and inter RAT

Th

rese

ho

lds

giv

en a

s ex

am

ple

34

Cell Reselection Parameters

Parameter Object Range Default Value Recommended Value Class

qHyst1 CellSelectionInfo Int [040] (dBm)

Step = 2

10 4 C2

qHyst2 CellSelectionInfo

Int [040] (dB)

Step = 2

4 6 C2

qOffset1sn GSMCell

Int [-5050] (dB) 0 TBD C0

qOffset2sn UMTSFDDNeighbouring Int [-5050] (dB) 0 TBD C0

qualMeas CPICH_EcNo or

CPICH_RSCP

CPICH_EcNo NA Static

tReselection CellSelectionInfo Int [031] (s) 31 6 C2

35

Measurements

The different types of air interface measurements are

bull Intra-frequency measurements measurements on downlink physical channels at the same frequency as the active set A measurement object corresponds to one cell

bull Inter-frequency measurements measurements on downlink physical channels at frequencies that differ from the frequency of the active set A measurement object corresponds to one cell

bull Inter-RAT measurements measurements on downlink physical channels belonging to another radio access technology than UTRAN eg GSM A measurement object corresponds to one cell

36

Handover (Handoff) bull There are following categories of handover (also referred to as handoff)

bull Hard handover means that all the old radio links in the UE are removed before

the new radio links are established Hard handover can be seamless or non-seamless Seamless hard handover means that the handover is not perceptible to the user In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover

bull Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN Soft handover is performed by means of macro diversity which refers to the condition that several radio links are active at the same time

bull Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (ie the site of co-located base stations from which several sector-cells are served

37

Handover (Handoff) bull The most obvious cause for performing a handover is that due to its movement a user

can be served in another cell more efficiently (like less power emission less interference) It may however also be performed for other reasons such as system load control

bull Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (ie the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set)

bull The maximum active set size at the RNC is determined by the parameter MaxAciveSetSize

bull 3 to 4 cells the larger the active set size the more likely it is that Iub link efficiency is reduced (more than one resource for a single connection due to SHO)

bull Cells which are not included in the active set but are included in the CELL_INFO_LIST belong to the Monitored Set

bull Cells detected by the UE which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state

38

PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)

bull The primary cell election algorithm applies to soft HO It is used for monitored set determination and a pointer to mobility parameter

bull The Monitored Set should be updated each time the primary cell of active set changes A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set The message contains the cell to addremove from the monitored and should follow the ACIVE SET UPDATE message

bull The primary cell algorithm is called from SHO algorithm therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC

Measurement control used for monitored set update

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

Case 1 Drop due to missing neighbor

Problem Detected Nighbor (DN)

bull UE sends a Measurement Report that contains an event1a means adding a new RL (cell) to Active Set

bull If the reported cell is not in the current neighbor cell list and the reported EcNo is better than the best serving cell EcNo in AS by some dBs (set by a RNC parameter)

bull If for any reason the new cell can not be added to AS call will be released

2 If the UE reconnects to the network immediately after call drop and the scramble of the cell that UE camps on is different from that upon call drop missing neighbor cell is probable Confirm it by measurement control (search the messages back from call drop for the latest intra-frequency measurement control message Check the neighbor cell list of this measurement control message)

3 UEs might report detected set information If corresponding scramblling code information is in the monitor set before call drop the cause must be missing neighbor cell

Weak Coverage

bull Weak coverage usually refers to weak RSCP Uplink or downlink DCH power helps to confirm the weak coverage is in uplink or downlink by the following methods bull If the uplink transmission power reaches the maximum before call drop the uplink BLER is weak the call drop is probably due to weak uplink coverage bull Out of Uplink coverage may be caused by not only by low CPICH_RSCP But also by high UL_RSSI bull If the downlink transmission power reaches the maximum before call drop and the downlink BLER is weak the call drop is probably due to weak downlink coverage High downlink RSSI received by UE is an indication of weak coverage during that time UE tries to increase its target SIR to listen to the network Multipath propagation yields signal paths of different lengths with different times of arrival at the receiver Typical values of time delays (μs) are 02 in Open environment 05 Suburban and 3 in Urban When coded data rates of services are incompatible ldquoRate Matchingrdquo is used to equalize the data rates ndash Rate Matching may be performed by 1048707 Padding with extra bits 1048707 Puncturing of bits using a pseudo-random algorithm

Case 2 Drop due to Poor Coverage (low RSCP)

Problem Poor DL coverage

When UE gets to an area with low RSCP ( lt -105 dBm)

regardless EcNo values there is high risk for drop

UE will likely ramp up the transmitted power and reach its

max power The UL BLER will probably increase and SIR

target cannot maintain anymore finally the call drops

Explain the concept of Cell Breathing How is the accounted for in the linkBudget Ans Io or No (the interference part of EcIo and EbNo) increase as the traffic on the network increases since everyone is using the same frequency Therefore as Io or No increases the UE or BTS needs to use more power to maintain the same EbNo or EcIo When the power required is more thanthe maximum power allowed the connection cannot be made Users at the cell edge are usually the first to lose service hence the service area of a cell shrinks As traffic decreases the reverse happens and the service area increases They should say that it is accounted for in the Noise Rise Margin found in the Link Budget

Interference

In downlink when the active set CPICH RSCP is greater than ndash85 dBm and the active set EcIo is gt= ndash12 dB the call drop is probably due to downlink interference Downlink interference usually refers to pilot pollution Interference in Uplink is detected when the Uplink RTWP exceeds a certain configurable Threshold In general Expected level of RTWP is formed by sum of the the following components 1Thermal noise floor (KTB =-108132dBm) 2Node B noise figure (Typically 18 dB for our equipment) 3Noise raise due to load (50 load in Uplink corresponds to 3 db) 4Compensation for inaccuracies in Radio NW algoriths (2dB) WHAT IS THE PILOT POLLUTION Area where the SIR (Signal interference ratio) is too low and below the expected value (EcIo gt= -12 dB) there is too much interference =gt the mobile cannot understand the pilot channel HOW TO REDUCE THE PILOT POLLUTION PROBLEM Maximise the signal inside the best server Minimise the energy overshoot from the neighbor cells with some RF consideration (tilt azimuthhellip)

Pilot Pollution

Excessive strong pilots exist at a point but no one is strong enough to be primary pilot 1 Definition of strong pilot (CPICH_RSCP gt ThRSCP) 2 Definition of Excessive CPICH_Number gt ThN

3 Definition of no best server strong enoughrdquo CPICH_RSCP1st-CPICH_RSCP(ThN+1)th lt ThRSCP_Relative

Following is the case from cluster Mongkok West Probable Solution adjust engineering parameters of an antenna so that a best server forms around the antenna For handover problems caused by pilot pollution adjust engineering parameters of other antennas so that signals from other antennas becomes weaker and the number of pilots drops For this case reduce antenna height of site SGI Many definitions A cell that has a high signal strength at a location but is not part of the active set A cell that meets thecriteria for addition into the Active Set but can not enter because the active set is full

1UE fails to receive active set update command (Delayed Handover) After UE reports measurement message the EcIo of original cell signals decreases sharply When the RNC sends active set update message the UE powers off the transmitter due to asynchronization The UE cannot receive active set update message This may be due to EcIo of original cell decreases sharply and that of the target cell increases greatly (Turnings) 2 The best server changes frequently Two or more cells alternate to be the best server The RSCP of the best server is strong The period for each cell to be the best server is short Probable solution Lower the triggering time for event 1a adjust antennas to expand the handover area adjust the antenna to form a best server reduce Ping-pong handover by setting the handover parameter of 1B event

17

Radio Interface Protocol Architecture

Radio

Interface

Protocol

Architecture

Transport Channel (SAP)

Physical Channels

Logical Channel

L3

contr

ol

contr

ol

contr

ol

contr

ol

Logical

Channels

Transport

Channels

C-plane signalling U-plane information

PHY

L2MAC

L1

RLC

DCNtGC

L2RLC

MAC

RLC

RLCRLC

RLC

RLCRLC

RLC

Duplication avoidance

UuS boundary

BMC L2BMC

RRC

control

PDCPPDCP L2PDCP

DCNtGC

Packet Data Convergence Protocol

Is only for PS domain services

18

Radio Interface protocol architecture

L2MAC

L2RLC

L1

RLC

MAC

L3 RRC

PHY

Transport Channels

Logical Channels

C-plane signalling U-plane information

GC Nt DC

RLC RLC

RLC

GC NT DC RRC RLC MAC

General Control Notification Dedicated Control Radio Resource Control Radio Link Control Medium Access Control

UTRA Protocol Architecture

19

Logical Channel Structure

Synchronisation Control Channel (SCCH)

Broadcast Control Channel (BCCH)

Paging Control Channel (PCCH)

Dedicated Control Channel (DCCH)

Dedicated Control Channel (DCCH)Common Control Channel (CCCH)

Control Channel (CCH)

Dedicated Traffic Channel (DTCH)Traffic Channel (TCH)

ODMA Dedicated Control Channel (ODCCH)

ODMA Common Control Channel (OCCCH)

ODMA Dedicated Traffic Channel (ODTCH)

Common Traffic Channel (CTCH)

Shared Channel Control Channel (SHCCH)

(TDD)

(ODMA)

(ODMA)

(TDD)

20

Channels

Transport Channels Dedicated Transport Channel (DCH) ULDL mapped to DCCH and DTCH Broadcast Channel (BCH) DL mapped to BCCH Forward Access Channel (FACH) DL mapped to BCCH CCCH CTCH DCCH and DTCH Paging Channel (PCH) DL mapped to PCCH Random Access Channel (RACH) UL mapped to CCCH DCCH and DTCH Uplink Common Packet Channel (CPCH) UL mapped to DCCH and DTCH Downlink Shared Channel (DSCH) DL mapped to DCCH and DTCH The speech service in UMTS will employ the Adaptive Multi - rate technique 1048707 This is a single integrated codec with eight source rates 122 102 795 740 670 590 515 and 475 kbps To facilitate interoperability with existing cellular networks some of the modes are the same as in existing networks

21

Channels Physical Channels Primary Common Control Physical Channel (PCCPCH) mapped to BCH Secondary Common Control Physical Channel (SCCPCH) mapped to FACH PCH Physical Random Access Channel (PRACH) mapped to RACH Dedicated Physical Data Channel (DPDCH) mapped to DCH Dedicated Physical Control Channel (DPCCH) mapped to DCH Physical Downlink Shared Channel (PDSCH) mapped to DSCH Physical Common Packet Channel (PCPCH) mapped to CPCH Synchronisation Channel (SCH) Common Pilot Channel (CPICH) Acquisition Indicator Channel (AICH) Paging Indication Channel (PICH) CPCH Status Indication Channel (CSICH) Collision DetectionChannel Assignment Indication Channel (CDCA-ICH)

AMR

The bit rate of the AMR speech connection is controlled by the radio access network depending on the air interface loading and the quality of the speech connections During high loading such as during busy hours it is possible to use lower AMR bit rates to offer higher capacity while providing slightly lower speech quality Also if the mobile is running out of the cell coverage area and using its maximum transmission power a lower AMR bit rate can be used to extend the cell coverage area Adaptive multi-rate also contains error concealment The purpose of frame substitution is to conceal the effect of lost speech frames If several frames are lost muting is used to prevent possibly annoying sounds as a result of the frame substitution In P5 with AMR NB it is possible to use lower speech codec rates than 122 kbps The radio network also supports 795 kbps 59 kbps and 475 kbps AMR codecs There is no adaptation in the sense that AMR codecs are changed during an ongoing speech connection rather there is a possibility to adapt the rate at initial selection

23

Link Budget

bull Cell range amp cell capacity are limited by the same parameters

Interference in uplink

Power in downlink

bull Cell breathing phenomenon

ldquoPowerrdquo Link Budget

Tx power + All Gains ndash Path Loss ndash Other losses = Rx power

Path loss = Tx Signal + All Gains ndash Other losses ndash Rx power

Max Path loss = Tx Signal + All Gains ndash Other losses ndash Rx sensitivity

25

Initial Cell Search

The initial Cell Search is carried out in three steps

Step 1 Slot synchronisation - using the primary synchronisation channel

Step 2 Frame synchronisation and code-group identification- using the secondary synchronisation channel

Step 3 Scrambling-code identification-identified through symbol- by-symbol correlation over the primary CCPCH with all the scrambling codes within the code group

26

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

27

Frame Synchronization

helliphellip

2560 chips

acp

Slot

P-SCH acp

Slot

16 11 S-SCH

acp

Slot

2 Group 4 Slot 121314

slot number Scrambling Code Group 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Group 0 1 1 2 8 9 10 15 8 10 16 2 7 15 7 16

Group 1 1 1 5 16 7 3 14 16 3 10 5 12 14 12 10

Group 2 1 2 1 15 5 5 12 16 6 11 2 16 11 15 12

Group 3 1 2 3 1 8 6 5 2 5 8 4 4 6 3 7

Group 4 1 2 16 6 6 11 15 5 12 1 15 12 16 11 2

hellip

Group 61 9 10 13 10 11 15 15 9 16 12 14 13 16 14 11

Group 62 9 11 12 15 12 9 13 13 11 14 10 16 15 14 16

Group 63 9 12 10 15 13 14 9 14 15 11 11 13 12 16 10

256 chips

S-SCH

P-SCH

512 Primary Scrambling Codes divided into 64 groups

28

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

29

Cell Information

P-SCH Coverage indication Slot Synchronization

S-SCH Frame Synchronization Group identification

P-CPICH Scrambling Code Identification

P-CCPCH System Information Broadcast

Logical Channel

BCCH

Transport Channel

BCH

Physical Channel

P-CCPCH

OVSF Cch2561

Primary Scrambling Code

Transmitted during 910th slot

Bit Rate 123 kbps RLC Mode transparent

Mac-B transparent

30

Intra-Frequency Cell Reselection sample

Time

Quality

Serving CellServing Cell

Neighboring Cell

Neighboring Cell

Neighboring

cell criterion S

is fulfilled and is

ranked

Neighboring cell

better ranking

than Serving cell

UE perform cell

reselection

Treselections

Qmeans + Qhyst2s

Qmeann - Qoffset2sn

Qqualmin

UE perform

intra-frequency

measurements

Qqualmin +

SIntraSearch

31

Cell selection and reselection Cell Selection criteria

The cell selection criterion S is fulfilled when

where

Squal = Qqualmeas ndash Qqualmin

Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

Pcompensation ＝ max(UE_TXPWR_MAX_RACH ndash P_MAX 0)

for FDD cells Srxlev gt 0 AND Squal gt 0

for TDD cells Srxlev gt 0

for GSM cells Srxlev gt 0

32

Cell Selection Parameters

Parameter Object Range Default Value Recommended Value Class

qQualMin CellSelectionInfo Int [-240]

(dB)

-10 -16 C2

qRxLevMin CellSelectionInfo Int [-115-25]

Step = 2 (dBm)

-45 -115 C2

maxAllowedUlTxPower UlUsPowerConf Int [-5033]

(dBm)

33 33 C3

P_Max = maximum UE output power (dBm) according to its class

Power Class Maximum Output Power (dBm)

1 33

2 27

3 24

4 21

33

Cell Reselection Procedure

Squal

SintraSearch

SinterSearch

SinterRAT Measurement on

same frequency Measurement on

other frequencies Measurement on

other RAT

If Squal = CPICH_EcNo ndash qQualMin lt Threshold

Associated measurements are performed

Thresholds are broadcasted in SIB 11

In UMTS02 2 types of measurements are done Intra frequency and inter RAT

Th

rese

ho

lds

giv

en a

s ex

am

ple

34

Cell Reselection Parameters

Parameter Object Range Default Value Recommended Value Class

qHyst1 CellSelectionInfo Int [040] (dBm)

Step = 2

10 4 C2

qHyst2 CellSelectionInfo

Int [040] (dB)

Step = 2

4 6 C2

qOffset1sn GSMCell

Int [-5050] (dB) 0 TBD C0

qOffset2sn UMTSFDDNeighbouring Int [-5050] (dB) 0 TBD C0

qualMeas CPICH_EcNo or

CPICH_RSCP

CPICH_EcNo NA Static

tReselection CellSelectionInfo Int [031] (s) 31 6 C2

35

Measurements

The different types of air interface measurements are

bull Intra-frequency measurements measurements on downlink physical channels at the same frequency as the active set A measurement object corresponds to one cell

bull Inter-frequency measurements measurements on downlink physical channels at frequencies that differ from the frequency of the active set A measurement object corresponds to one cell

bull Inter-RAT measurements measurements on downlink physical channels belonging to another radio access technology than UTRAN eg GSM A measurement object corresponds to one cell

36

Handover (Handoff) bull There are following categories of handover (also referred to as handoff)

bull Hard handover means that all the old radio links in the UE are removed before

the new radio links are established Hard handover can be seamless or non-seamless Seamless hard handover means that the handover is not perceptible to the user In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover

bull Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN Soft handover is performed by means of macro diversity which refers to the condition that several radio links are active at the same time

bull Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (ie the site of co-located base stations from which several sector-cells are served

37

Handover (Handoff) bull The most obvious cause for performing a handover is that due to its movement a user

can be served in another cell more efficiently (like less power emission less interference) It may however also be performed for other reasons such as system load control

bull Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (ie the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set)

bull The maximum active set size at the RNC is determined by the parameter MaxAciveSetSize

bull 3 to 4 cells the larger the active set size the more likely it is that Iub link efficiency is reduced (more than one resource for a single connection due to SHO)

bull Cells which are not included in the active set but are included in the CELL_INFO_LIST belong to the Monitored Set

bull Cells detected by the UE which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state

38

PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)

bull The primary cell election algorithm applies to soft HO It is used for monitored set determination and a pointer to mobility parameter

bull The Monitored Set should be updated each time the primary cell of active set changes A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set The message contains the cell to addremove from the monitored and should follow the ACIVE SET UPDATE message

bull The primary cell algorithm is called from SHO algorithm therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC

Measurement control used for monitored set update

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

Weak Coverage

bull Weak coverage usually refers to weak RSCP Uplink or downlink DCH power helps to confirm the weak coverage is in uplink or downlink by the following methods bull If the uplink transmission power reaches the maximum before call drop the uplink BLER is weak the call drop is probably due to weak uplink coverage bull Out of Uplink coverage may be caused by not only by low CPICH_RSCP But also by high UL_RSSI bull If the downlink transmission power reaches the maximum before call drop and the downlink BLER is weak the call drop is probably due to weak downlink coverage High downlink RSSI received by UE is an indication of weak coverage during that time UE tries to increase its target SIR to listen to the network Multipath propagation yields signal paths of different lengths with different times of arrival at the receiver Typical values of time delays (μs) are 02 in Open environment 05 Suburban and 3 in Urban When coded data rates of services are incompatible ldquoRate Matchingrdquo is used to equalize the data rates ndash Rate Matching may be performed by 1048707 Padding with extra bits 1048707 Puncturing of bits using a pseudo-random algorithm

Case 2 Drop due to Poor Coverage (low RSCP)

Problem Poor DL coverage

When UE gets to an area with low RSCP ( lt -105 dBm)

regardless EcNo values there is high risk for drop

UE will likely ramp up the transmitted power and reach its

max power The UL BLER will probably increase and SIR

target cannot maintain anymore finally the call drops

Explain the concept of Cell Breathing How is the accounted for in the linkBudget Ans Io or No (the interference part of EcIo and EbNo) increase as the traffic on the network increases since everyone is using the same frequency Therefore as Io or No increases the UE or BTS needs to use more power to maintain the same EbNo or EcIo When the power required is more thanthe maximum power allowed the connection cannot be made Users at the cell edge are usually the first to lose service hence the service area of a cell shrinks As traffic decreases the reverse happens and the service area increases They should say that it is accounted for in the Noise Rise Margin found in the Link Budget

Interference

In downlink when the active set CPICH RSCP is greater than ndash85 dBm and the active set EcIo is gt= ndash12 dB the call drop is probably due to downlink interference Downlink interference usually refers to pilot pollution Interference in Uplink is detected when the Uplink RTWP exceeds a certain configurable Threshold In general Expected level of RTWP is formed by sum of the the following components 1Thermal noise floor (KTB =-108132dBm) 2Node B noise figure (Typically 18 dB for our equipment) 3Noise raise due to load (50 load in Uplink corresponds to 3 db) 4Compensation for inaccuracies in Radio NW algoriths (2dB) WHAT IS THE PILOT POLLUTION Area where the SIR (Signal interference ratio) is too low and below the expected value (EcIo gt= -12 dB) there is too much interference =gt the mobile cannot understand the pilot channel HOW TO REDUCE THE PILOT POLLUTION PROBLEM Maximise the signal inside the best server Minimise the energy overshoot from the neighbor cells with some RF consideration (tilt azimuthhellip)

Pilot Pollution

Excessive strong pilots exist at a point but no one is strong enough to be primary pilot 1 Definition of strong pilot (CPICH_RSCP gt ThRSCP) 2 Definition of Excessive CPICH_Number gt ThN

3 Definition of no best server strong enoughrdquo CPICH_RSCP1st-CPICH_RSCP(ThN+1)th lt ThRSCP_Relative

Following is the case from cluster Mongkok West Probable Solution adjust engineering parameters of an antenna so that a best server forms around the antenna For handover problems caused by pilot pollution adjust engineering parameters of other antennas so that signals from other antennas becomes weaker and the number of pilots drops For this case reduce antenna height of site SGI Many definitions A cell that has a high signal strength at a location but is not part of the active set A cell that meets thecriteria for addition into the Active Set but can not enter because the active set is full

1UE fails to receive active set update command (Delayed Handover) After UE reports measurement message the EcIo of original cell signals decreases sharply When the RNC sends active set update message the UE powers off the transmitter due to asynchronization The UE cannot receive active set update message This may be due to EcIo of original cell decreases sharply and that of the target cell increases greatly (Turnings) 2 The best server changes frequently Two or more cells alternate to be the best server The RSCP of the best server is strong The period for each cell to be the best server is short Probable solution Lower the triggering time for event 1a adjust antennas to expand the handover area adjust the antenna to form a best server reduce Ping-pong handover by setting the handover parameter of 1B event

17

Radio Interface Protocol Architecture

Radio

Interface

Protocol

Architecture

Transport Channel (SAP)

Physical Channels

Logical Channel

L3

contr

ol

contr

ol

contr

ol

contr

ol

Logical

Channels

Transport

Channels

C-plane signalling U-plane information

PHY

L2MAC

L1

RLC

DCNtGC

L2RLC

MAC

RLC

RLCRLC

RLC

RLCRLC

RLC

Duplication avoidance

UuS boundary

BMC L2BMC

RRC

control

PDCPPDCP L2PDCP

DCNtGC

Packet Data Convergence Protocol

Is only for PS domain services

18

Radio Interface protocol architecture

L2MAC

L2RLC

L1

RLC

MAC

L3 RRC

PHY

Transport Channels

Logical Channels

C-plane signalling U-plane information

GC Nt DC

RLC RLC

RLC

GC NT DC RRC RLC MAC

General Control Notification Dedicated Control Radio Resource Control Radio Link Control Medium Access Control

UTRA Protocol Architecture

19

Logical Channel Structure

Synchronisation Control Channel (SCCH)

Broadcast Control Channel (BCCH)

Paging Control Channel (PCCH)

Dedicated Control Channel (DCCH)

Dedicated Control Channel (DCCH)Common Control Channel (CCCH)

Control Channel (CCH)

Dedicated Traffic Channel (DTCH)Traffic Channel (TCH)

ODMA Dedicated Control Channel (ODCCH)

ODMA Common Control Channel (OCCCH)

ODMA Dedicated Traffic Channel (ODTCH)

Common Traffic Channel (CTCH)

Shared Channel Control Channel (SHCCH)

(TDD)

(ODMA)

(ODMA)

(TDD)

20

Channels

Transport Channels Dedicated Transport Channel (DCH) ULDL mapped to DCCH and DTCH Broadcast Channel (BCH) DL mapped to BCCH Forward Access Channel (FACH) DL mapped to BCCH CCCH CTCH DCCH and DTCH Paging Channel (PCH) DL mapped to PCCH Random Access Channel (RACH) UL mapped to CCCH DCCH and DTCH Uplink Common Packet Channel (CPCH) UL mapped to DCCH and DTCH Downlink Shared Channel (DSCH) DL mapped to DCCH and DTCH The speech service in UMTS will employ the Adaptive Multi - rate technique 1048707 This is a single integrated codec with eight source rates 122 102 795 740 670 590 515 and 475 kbps To facilitate interoperability with existing cellular networks some of the modes are the same as in existing networks

21

Channels Physical Channels Primary Common Control Physical Channel (PCCPCH) mapped to BCH Secondary Common Control Physical Channel (SCCPCH) mapped to FACH PCH Physical Random Access Channel (PRACH) mapped to RACH Dedicated Physical Data Channel (DPDCH) mapped to DCH Dedicated Physical Control Channel (DPCCH) mapped to DCH Physical Downlink Shared Channel (PDSCH) mapped to DSCH Physical Common Packet Channel (PCPCH) mapped to CPCH Synchronisation Channel (SCH) Common Pilot Channel (CPICH) Acquisition Indicator Channel (AICH) Paging Indication Channel (PICH) CPCH Status Indication Channel (CSICH) Collision DetectionChannel Assignment Indication Channel (CDCA-ICH)

AMR

The bit rate of the AMR speech connection is controlled by the radio access network depending on the air interface loading and the quality of the speech connections During high loading such as during busy hours it is possible to use lower AMR bit rates to offer higher capacity while providing slightly lower speech quality Also if the mobile is running out of the cell coverage area and using its maximum transmission power a lower AMR bit rate can be used to extend the cell coverage area Adaptive multi-rate also contains error concealment The purpose of frame substitution is to conceal the effect of lost speech frames If several frames are lost muting is used to prevent possibly annoying sounds as a result of the frame substitution In P5 with AMR NB it is possible to use lower speech codec rates than 122 kbps The radio network also supports 795 kbps 59 kbps and 475 kbps AMR codecs There is no adaptation in the sense that AMR codecs are changed during an ongoing speech connection rather there is a possibility to adapt the rate at initial selection

23

Link Budget

bull Cell range amp cell capacity are limited by the same parameters

Interference in uplink

Power in downlink

bull Cell breathing phenomenon

ldquoPowerrdquo Link Budget

Tx power + All Gains ndash Path Loss ndash Other losses = Rx power

Path loss = Tx Signal + All Gains ndash Other losses ndash Rx power

Max Path loss = Tx Signal + All Gains ndash Other losses ndash Rx sensitivity

25

Initial Cell Search

The initial Cell Search is carried out in three steps

Step 1 Slot synchronisation - using the primary synchronisation channel

Step 2 Frame synchronisation and code-group identification- using the secondary synchronisation channel

Step 3 Scrambling-code identification-identified through symbol- by-symbol correlation over the primary CCPCH with all the scrambling codes within the code group

26

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

27

Frame Synchronization

helliphellip

2560 chips

acp

Slot

P-SCH acp

Slot

16 11 S-SCH

acp

Slot

2 Group 4 Slot 121314

slot number Scrambling Code Group 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Group 0 1 1 2 8 9 10 15 8 10 16 2 7 15 7 16

Group 1 1 1 5 16 7 3 14 16 3 10 5 12 14 12 10

Group 2 1 2 1 15 5 5 12 16 6 11 2 16 11 15 12

Group 3 1 2 3 1 8 6 5 2 5 8 4 4 6 3 7

Group 4 1 2 16 6 6 11 15 5 12 1 15 12 16 11 2

hellip

Group 61 9 10 13 10 11 15 15 9 16 12 14 13 16 14 11

Group 62 9 11 12 15 12 9 13 13 11 14 10 16 15 14 16

Group 63 9 12 10 15 13 14 9 14 15 11 11 13 12 16 10

256 chips

S-SCH

P-SCH

512 Primary Scrambling Codes divided into 64 groups

28

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

29

Cell Information

P-SCH Coverage indication Slot Synchronization

S-SCH Frame Synchronization Group identification

P-CPICH Scrambling Code Identification

P-CCPCH System Information Broadcast

Logical Channel

BCCH

Transport Channel

BCH

Physical Channel

P-CCPCH

OVSF Cch2561

Primary Scrambling Code

Transmitted during 910th slot

Bit Rate 123 kbps RLC Mode transparent

Mac-B transparent

30

Intra-Frequency Cell Reselection sample

Time

Quality

Serving CellServing Cell

Neighboring Cell

Neighboring Cell

Neighboring

cell criterion S

is fulfilled and is

ranked

Neighboring cell

better ranking

than Serving cell

UE perform cell

reselection

Treselections

Qmeans + Qhyst2s

Qmeann - Qoffset2sn

Qqualmin

UE perform

intra-frequency

measurements

Qqualmin +

SIntraSearch

31

Cell selection and reselection Cell Selection criteria

The cell selection criterion S is fulfilled when

where

Squal = Qqualmeas ndash Qqualmin

Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

Pcompensation ＝ max(UE_TXPWR_MAX_RACH ndash P_MAX 0)

for FDD cells Srxlev gt 0 AND Squal gt 0

for TDD cells Srxlev gt 0

for GSM cells Srxlev gt 0

32

Cell Selection Parameters

Parameter Object Range Default Value Recommended Value Class

qQualMin CellSelectionInfo Int [-240]

(dB)

-10 -16 C2

qRxLevMin CellSelectionInfo Int [-115-25]

Step = 2 (dBm)

-45 -115 C2

maxAllowedUlTxPower UlUsPowerConf Int [-5033]

(dBm)

33 33 C3

P_Max = maximum UE output power (dBm) according to its class

Power Class Maximum Output Power (dBm)

1 33

2 27

3 24

4 21

33

Cell Reselection Procedure

Squal

SintraSearch

SinterSearch

SinterRAT Measurement on

same frequency Measurement on

other frequencies Measurement on

other RAT

If Squal = CPICH_EcNo ndash qQualMin lt Threshold

Associated measurements are performed

Thresholds are broadcasted in SIB 11

In UMTS02 2 types of measurements are done Intra frequency and inter RAT

Th

rese

ho

lds

giv

en a

s ex

am

ple

34

Cell Reselection Parameters

Parameter Object Range Default Value Recommended Value Class

qHyst1 CellSelectionInfo Int [040] (dBm)

Step = 2

10 4 C2

qHyst2 CellSelectionInfo

Int [040] (dB)

Step = 2

4 6 C2

qOffset1sn GSMCell

Int [-5050] (dB) 0 TBD C0

qOffset2sn UMTSFDDNeighbouring Int [-5050] (dB) 0 TBD C0

qualMeas CPICH_EcNo or

CPICH_RSCP

CPICH_EcNo NA Static

tReselection CellSelectionInfo Int [031] (s) 31 6 C2

35

Measurements

The different types of air interface measurements are

bull Intra-frequency measurements measurements on downlink physical channels at the same frequency as the active set A measurement object corresponds to one cell

bull Inter-frequency measurements measurements on downlink physical channels at frequencies that differ from the frequency of the active set A measurement object corresponds to one cell

bull Inter-RAT measurements measurements on downlink physical channels belonging to another radio access technology than UTRAN eg GSM A measurement object corresponds to one cell

36

Handover (Handoff) bull There are following categories of handover (also referred to as handoff)

bull Hard handover means that all the old radio links in the UE are removed before

the new radio links are established Hard handover can be seamless or non-seamless Seamless hard handover means that the handover is not perceptible to the user In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover

bull Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN Soft handover is performed by means of macro diversity which refers to the condition that several radio links are active at the same time

bull Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (ie the site of co-located base stations from which several sector-cells are served

37

Handover (Handoff) bull The most obvious cause for performing a handover is that due to its movement a user

can be served in another cell more efficiently (like less power emission less interference) It may however also be performed for other reasons such as system load control

bull Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (ie the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set)

bull The maximum active set size at the RNC is determined by the parameter MaxAciveSetSize

bull 3 to 4 cells the larger the active set size the more likely it is that Iub link efficiency is reduced (more than one resource for a single connection due to SHO)

bull Cells which are not included in the active set but are included in the CELL_INFO_LIST belong to the Monitored Set

bull Cells detected by the UE which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state

38

PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)

bull The primary cell election algorithm applies to soft HO It is used for monitored set determination and a pointer to mobility parameter

bull The Monitored Set should be updated each time the primary cell of active set changes A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set The message contains the cell to addremove from the monitored and should follow the ACIVE SET UPDATE message

bull The primary cell algorithm is called from SHO algorithm therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC

Measurement control used for monitored set update

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

Case 2 Drop due to Poor Coverage (low RSCP)

Problem Poor DL coverage

When UE gets to an area with low RSCP ( lt -105 dBm)

regardless EcNo values there is high risk for drop

UE will likely ramp up the transmitted power and reach its

max power The UL BLER will probably increase and SIR

target cannot maintain anymore finally the call drops

Explain the concept of Cell Breathing How is the accounted for in the linkBudget Ans Io or No (the interference part of EcIo and EbNo) increase as the traffic on the network increases since everyone is using the same frequency Therefore as Io or No increases the UE or BTS needs to use more power to maintain the same EbNo or EcIo When the power required is more thanthe maximum power allowed the connection cannot be made Users at the cell edge are usually the first to lose service hence the service area of a cell shrinks As traffic decreases the reverse happens and the service area increases They should say that it is accounted for in the Noise Rise Margin found in the Link Budget

Interference

In downlink when the active set CPICH RSCP is greater than ndash85 dBm and the active set EcIo is gt= ndash12 dB the call drop is probably due to downlink interference Downlink interference usually refers to pilot pollution Interference in Uplink is detected when the Uplink RTWP exceeds a certain configurable Threshold In general Expected level of RTWP is formed by sum of the the following components 1Thermal noise floor (KTB =-108132dBm) 2Node B noise figure (Typically 18 dB for our equipment) 3Noise raise due to load (50 load in Uplink corresponds to 3 db) 4Compensation for inaccuracies in Radio NW algoriths (2dB) WHAT IS THE PILOT POLLUTION Area where the SIR (Signal interference ratio) is too low and below the expected value (EcIo gt= -12 dB) there is too much interference =gt the mobile cannot understand the pilot channel HOW TO REDUCE THE PILOT POLLUTION PROBLEM Maximise the signal inside the best server Minimise the energy overshoot from the neighbor cells with some RF consideration (tilt azimuthhellip)

Pilot Pollution

Excessive strong pilots exist at a point but no one is strong enough to be primary pilot 1 Definition of strong pilot (CPICH_RSCP gt ThRSCP) 2 Definition of Excessive CPICH_Number gt ThN

3 Definition of no best server strong enoughrdquo CPICH_RSCP1st-CPICH_RSCP(ThN+1)th lt ThRSCP_Relative

Following is the case from cluster Mongkok West Probable Solution adjust engineering parameters of an antenna so that a best server forms around the antenna For handover problems caused by pilot pollution adjust engineering parameters of other antennas so that signals from other antennas becomes weaker and the number of pilots drops For this case reduce antenna height of site SGI Many definitions A cell that has a high signal strength at a location but is not part of the active set A cell that meets thecriteria for addition into the Active Set but can not enter because the active set is full

1UE fails to receive active set update command (Delayed Handover) After UE reports measurement message the EcIo of original cell signals decreases sharply When the RNC sends active set update message the UE powers off the transmitter due to asynchronization The UE cannot receive active set update message This may be due to EcIo of original cell decreases sharply and that of the target cell increases greatly (Turnings) 2 The best server changes frequently Two or more cells alternate to be the best server The RSCP of the best server is strong The period for each cell to be the best server is short Probable solution Lower the triggering time for event 1a adjust antennas to expand the handover area adjust the antenna to form a best server reduce Ping-pong handover by setting the handover parameter of 1B event

17

Radio Interface Protocol Architecture

Radio

Interface

Protocol

Architecture

Transport Channel (SAP)

Physical Channels

Logical Channel

L3

contr

ol

contr

ol

contr

ol

contr

ol

Logical

Channels

Transport

Channels

C-plane signalling U-plane information

PHY

L2MAC

L1

RLC

DCNtGC

L2RLC

MAC

RLC

RLCRLC

RLC

RLCRLC

RLC

Duplication avoidance

UuS boundary

BMC L2BMC

RRC

control

PDCPPDCP L2PDCP

DCNtGC

Packet Data Convergence Protocol

Is only for PS domain services

18

Radio Interface protocol architecture

L2MAC

L2RLC

L1

RLC

MAC

L3 RRC

PHY

Transport Channels

Logical Channels

C-plane signalling U-plane information

GC Nt DC

RLC RLC

RLC

GC NT DC RRC RLC MAC

General Control Notification Dedicated Control Radio Resource Control Radio Link Control Medium Access Control

UTRA Protocol Architecture

19

Logical Channel Structure

Synchronisation Control Channel (SCCH)

Broadcast Control Channel (BCCH)

Paging Control Channel (PCCH)

Dedicated Control Channel (DCCH)

Dedicated Control Channel (DCCH)Common Control Channel (CCCH)

Control Channel (CCH)

Dedicated Traffic Channel (DTCH)Traffic Channel (TCH)

ODMA Dedicated Control Channel (ODCCH)

ODMA Common Control Channel (OCCCH)

ODMA Dedicated Traffic Channel (ODTCH)

Common Traffic Channel (CTCH)

Shared Channel Control Channel (SHCCH)

(TDD)

(ODMA)

(ODMA)

(TDD)

20

Channels

Transport Channels Dedicated Transport Channel (DCH) ULDL mapped to DCCH and DTCH Broadcast Channel (BCH) DL mapped to BCCH Forward Access Channel (FACH) DL mapped to BCCH CCCH CTCH DCCH and DTCH Paging Channel (PCH) DL mapped to PCCH Random Access Channel (RACH) UL mapped to CCCH DCCH and DTCH Uplink Common Packet Channel (CPCH) UL mapped to DCCH and DTCH Downlink Shared Channel (DSCH) DL mapped to DCCH and DTCH The speech service in UMTS will employ the Adaptive Multi - rate technique 1048707 This is a single integrated codec with eight source rates 122 102 795 740 670 590 515 and 475 kbps To facilitate interoperability with existing cellular networks some of the modes are the same as in existing networks

21

Channels Physical Channels Primary Common Control Physical Channel (PCCPCH) mapped to BCH Secondary Common Control Physical Channel (SCCPCH) mapped to FACH PCH Physical Random Access Channel (PRACH) mapped to RACH Dedicated Physical Data Channel (DPDCH) mapped to DCH Dedicated Physical Control Channel (DPCCH) mapped to DCH Physical Downlink Shared Channel (PDSCH) mapped to DSCH Physical Common Packet Channel (PCPCH) mapped to CPCH Synchronisation Channel (SCH) Common Pilot Channel (CPICH) Acquisition Indicator Channel (AICH) Paging Indication Channel (PICH) CPCH Status Indication Channel (CSICH) Collision DetectionChannel Assignment Indication Channel (CDCA-ICH)

AMR

The bit rate of the AMR speech connection is controlled by the radio access network depending on the air interface loading and the quality of the speech connections During high loading such as during busy hours it is possible to use lower AMR bit rates to offer higher capacity while providing slightly lower speech quality Also if the mobile is running out of the cell coverage area and using its maximum transmission power a lower AMR bit rate can be used to extend the cell coverage area Adaptive multi-rate also contains error concealment The purpose of frame substitution is to conceal the effect of lost speech frames If several frames are lost muting is used to prevent possibly annoying sounds as a result of the frame substitution In P5 with AMR NB it is possible to use lower speech codec rates than 122 kbps The radio network also supports 795 kbps 59 kbps and 475 kbps AMR codecs There is no adaptation in the sense that AMR codecs are changed during an ongoing speech connection rather there is a possibility to adapt the rate at initial selection

23

Link Budget

bull Cell range amp cell capacity are limited by the same parameters

Interference in uplink

Power in downlink

bull Cell breathing phenomenon

ldquoPowerrdquo Link Budget

Tx power + All Gains ndash Path Loss ndash Other losses = Rx power

Path loss = Tx Signal + All Gains ndash Other losses ndash Rx power

Max Path loss = Tx Signal + All Gains ndash Other losses ndash Rx sensitivity

25

Initial Cell Search

The initial Cell Search is carried out in three steps

Step 1 Slot synchronisation - using the primary synchronisation channel

Step 2 Frame synchronisation and code-group identification- using the secondary synchronisation channel

Step 3 Scrambling-code identification-identified through symbol- by-symbol correlation over the primary CCPCH with all the scrambling codes within the code group

26

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

27

Frame Synchronization

helliphellip

2560 chips

acp

Slot

P-SCH acp

Slot

16 11 S-SCH

acp

Slot

2 Group 4 Slot 121314

slot number Scrambling Code Group 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Group 0 1 1 2 8 9 10 15 8 10 16 2 7 15 7 16

Group 1 1 1 5 16 7 3 14 16 3 10 5 12 14 12 10

Group 2 1 2 1 15 5 5 12 16 6 11 2 16 11 15 12

Group 3 1 2 3 1 8 6 5 2 5 8 4 4 6 3 7

Group 4 1 2 16 6 6 11 15 5 12 1 15 12 16 11 2

hellip

Group 61 9 10 13 10 11 15 15 9 16 12 14 13 16 14 11

Group 62 9 11 12 15 12 9 13 13 11 14 10 16 15 14 16

Group 63 9 12 10 15 13 14 9 14 15 11 11 13 12 16 10

256 chips

S-SCH

P-SCH

512 Primary Scrambling Codes divided into 64 groups

28

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

29

Cell Information

P-SCH Coverage indication Slot Synchronization

S-SCH Frame Synchronization Group identification

P-CPICH Scrambling Code Identification

P-CCPCH System Information Broadcast

Logical Channel

BCCH

Transport Channel

BCH

Physical Channel

P-CCPCH

OVSF Cch2561

Primary Scrambling Code

Transmitted during 910th slot

Bit Rate 123 kbps RLC Mode transparent

Mac-B transparent

30

Intra-Frequency Cell Reselection sample

Time

Quality

Serving CellServing Cell

Neighboring Cell

Neighboring Cell

Neighboring

cell criterion S

is fulfilled and is

ranked

Neighboring cell

better ranking

than Serving cell

UE perform cell

reselection

Treselections

Qmeans + Qhyst2s

Qmeann - Qoffset2sn

Qqualmin

UE perform

intra-frequency

measurements

Qqualmin +

SIntraSearch

31

Cell selection and reselection Cell Selection criteria

The cell selection criterion S is fulfilled when

where

Squal = Qqualmeas ndash Qqualmin

Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

Pcompensation ＝ max(UE_TXPWR_MAX_RACH ndash P_MAX 0)

for FDD cells Srxlev gt 0 AND Squal gt 0

for TDD cells Srxlev gt 0

for GSM cells Srxlev gt 0

32

Cell Selection Parameters

Parameter Object Range Default Value Recommended Value Class

qQualMin CellSelectionInfo Int [-240]

(dB)

-10 -16 C2

qRxLevMin CellSelectionInfo Int [-115-25]

Step = 2 (dBm)

-45 -115 C2

maxAllowedUlTxPower UlUsPowerConf Int [-5033]

(dBm)

33 33 C3

P_Max = maximum UE output power (dBm) according to its class

Power Class Maximum Output Power (dBm)

1 33

2 27

3 24

4 21

33

Cell Reselection Procedure

Squal

SintraSearch

SinterSearch

SinterRAT Measurement on

same frequency Measurement on

other frequencies Measurement on

other RAT

If Squal = CPICH_EcNo ndash qQualMin lt Threshold

Associated measurements are performed

Thresholds are broadcasted in SIB 11

In UMTS02 2 types of measurements are done Intra frequency and inter RAT

Th

rese

ho

lds

giv

en a

s ex

am

ple

34

Cell Reselection Parameters

Parameter Object Range Default Value Recommended Value Class

qHyst1 CellSelectionInfo Int [040] (dBm)

Step = 2

10 4 C2

qHyst2 CellSelectionInfo

Int [040] (dB)

Step = 2

4 6 C2

qOffset1sn GSMCell

Int [-5050] (dB) 0 TBD C0

qOffset2sn UMTSFDDNeighbouring Int [-5050] (dB) 0 TBD C0

qualMeas CPICH_EcNo or

CPICH_RSCP

CPICH_EcNo NA Static

tReselection CellSelectionInfo Int [031] (s) 31 6 C2

35

Measurements

The different types of air interface measurements are

bull Intra-frequency measurements measurements on downlink physical channels at the same frequency as the active set A measurement object corresponds to one cell

bull Inter-frequency measurements measurements on downlink physical channels at frequencies that differ from the frequency of the active set A measurement object corresponds to one cell

bull Inter-RAT measurements measurements on downlink physical channels belonging to another radio access technology than UTRAN eg GSM A measurement object corresponds to one cell

36

Handover (Handoff) bull There are following categories of handover (also referred to as handoff)

bull Hard handover means that all the old radio links in the UE are removed before

the new radio links are established Hard handover can be seamless or non-seamless Seamless hard handover means that the handover is not perceptible to the user In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover

bull Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN Soft handover is performed by means of macro diversity which refers to the condition that several radio links are active at the same time

bull Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (ie the site of co-located base stations from which several sector-cells are served

37

Handover (Handoff) bull The most obvious cause for performing a handover is that due to its movement a user

can be served in another cell more efficiently (like less power emission less interference) It may however also be performed for other reasons such as system load control

bull Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (ie the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set)

bull The maximum active set size at the RNC is determined by the parameter MaxAciveSetSize

bull 3 to 4 cells the larger the active set size the more likely it is that Iub link efficiency is reduced (more than one resource for a single connection due to SHO)

bull Cells which are not included in the active set but are included in the CELL_INFO_LIST belong to the Monitored Set

bull Cells detected by the UE which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state

38

PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)

bull The primary cell election algorithm applies to soft HO It is used for monitored set determination and a pointer to mobility parameter

bull The Monitored Set should be updated each time the primary cell of active set changes A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set The message contains the cell to addremove from the monitored and should follow the ACIVE SET UPDATE message

bull The primary cell algorithm is called from SHO algorithm therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC

Measurement control used for monitored set update

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

Interference

In downlink when the active set CPICH RSCP is greater than ndash85 dBm and the active set EcIo is gt= ndash12 dB the call drop is probably due to downlink interference Downlink interference usually refers to pilot pollution Interference in Uplink is detected when the Uplink RTWP exceeds a certain configurable Threshold In general Expected level of RTWP is formed by sum of the the following components 1Thermal noise floor (KTB =-108132dBm) 2Node B noise figure (Typically 18 dB for our equipment) 3Noise raise due to load (50 load in Uplink corresponds to 3 db) 4Compensation for inaccuracies in Radio NW algoriths (2dB) WHAT IS THE PILOT POLLUTION Area where the SIR (Signal interference ratio) is too low and below the expected value (EcIo gt= -12 dB) there is too much interference =gt the mobile cannot understand the pilot channel HOW TO REDUCE THE PILOT POLLUTION PROBLEM Maximise the signal inside the best server Minimise the energy overshoot from the neighbor cells with some RF consideration (tilt azimuthhellip)

Pilot Pollution

Excessive strong pilots exist at a point but no one is strong enough to be primary pilot 1 Definition of strong pilot (CPICH_RSCP gt ThRSCP) 2 Definition of Excessive CPICH_Number gt ThN

3 Definition of no best server strong enoughrdquo CPICH_RSCP1st-CPICH_RSCP(ThN+1)th lt ThRSCP_Relative

Following is the case from cluster Mongkok West Probable Solution adjust engineering parameters of an antenna so that a best server forms around the antenna For handover problems caused by pilot pollution adjust engineering parameters of other antennas so that signals from other antennas becomes weaker and the number of pilots drops For this case reduce antenna height of site SGI Many definitions A cell that has a high signal strength at a location but is not part of the active set A cell that meets thecriteria for addition into the Active Set but can not enter because the active set is full

1UE fails to receive active set update command (Delayed Handover) After UE reports measurement message the EcIo of original cell signals decreases sharply When the RNC sends active set update message the UE powers off the transmitter due to asynchronization The UE cannot receive active set update message This may be due to EcIo of original cell decreases sharply and that of the target cell increases greatly (Turnings) 2 The best server changes frequently Two or more cells alternate to be the best server The RSCP of the best server is strong The period for each cell to be the best server is short Probable solution Lower the triggering time for event 1a adjust antennas to expand the handover area adjust the antenna to form a best server reduce Ping-pong handover by setting the handover parameter of 1B event

17

Radio Interface Protocol Architecture

Radio

Interface

Protocol

Architecture

Transport Channel (SAP)

Physical Channels

Logical Channel

L3

contr

ol

contr

ol

contr

ol

contr

ol

Logical

Channels

Transport

Channels

C-plane signalling U-plane information

PHY

L2MAC

L1

RLC

DCNtGC

L2RLC

MAC

RLC

RLCRLC

RLC

RLCRLC

RLC

Duplication avoidance

UuS boundary

BMC L2BMC

RRC

control

PDCPPDCP L2PDCP

DCNtGC

Packet Data Convergence Protocol

Is only for PS domain services

18

Radio Interface protocol architecture

L2MAC

L2RLC

L1

RLC

MAC

L3 RRC

PHY

Transport Channels

Logical Channels

C-plane signalling U-plane information

GC Nt DC

RLC RLC

RLC

GC NT DC RRC RLC MAC

General Control Notification Dedicated Control Radio Resource Control Radio Link Control Medium Access Control

UTRA Protocol Architecture

19

Logical Channel Structure

Synchronisation Control Channel (SCCH)

Broadcast Control Channel (BCCH)

Paging Control Channel (PCCH)

Dedicated Control Channel (DCCH)

Dedicated Control Channel (DCCH)Common Control Channel (CCCH)

Control Channel (CCH)

Dedicated Traffic Channel (DTCH)Traffic Channel (TCH)

ODMA Dedicated Control Channel (ODCCH)

ODMA Common Control Channel (OCCCH)

ODMA Dedicated Traffic Channel (ODTCH)

Common Traffic Channel (CTCH)

Shared Channel Control Channel (SHCCH)

(TDD)

(ODMA)

(ODMA)

(TDD)

20

Channels

Transport Channels Dedicated Transport Channel (DCH) ULDL mapped to DCCH and DTCH Broadcast Channel (BCH) DL mapped to BCCH Forward Access Channel (FACH) DL mapped to BCCH CCCH CTCH DCCH and DTCH Paging Channel (PCH) DL mapped to PCCH Random Access Channel (RACH) UL mapped to CCCH DCCH and DTCH Uplink Common Packet Channel (CPCH) UL mapped to DCCH and DTCH Downlink Shared Channel (DSCH) DL mapped to DCCH and DTCH The speech service in UMTS will employ the Adaptive Multi - rate technique 1048707 This is a single integrated codec with eight source rates 122 102 795 740 670 590 515 and 475 kbps To facilitate interoperability with existing cellular networks some of the modes are the same as in existing networks

21

Channels Physical Channels Primary Common Control Physical Channel (PCCPCH) mapped to BCH Secondary Common Control Physical Channel (SCCPCH) mapped to FACH PCH Physical Random Access Channel (PRACH) mapped to RACH Dedicated Physical Data Channel (DPDCH) mapped to DCH Dedicated Physical Control Channel (DPCCH) mapped to DCH Physical Downlink Shared Channel (PDSCH) mapped to DSCH Physical Common Packet Channel (PCPCH) mapped to CPCH Synchronisation Channel (SCH) Common Pilot Channel (CPICH) Acquisition Indicator Channel (AICH) Paging Indication Channel (PICH) CPCH Status Indication Channel (CSICH) Collision DetectionChannel Assignment Indication Channel (CDCA-ICH)

AMR

The bit rate of the AMR speech connection is controlled by the radio access network depending on the air interface loading and the quality of the speech connections During high loading such as during busy hours it is possible to use lower AMR bit rates to offer higher capacity while providing slightly lower speech quality Also if the mobile is running out of the cell coverage area and using its maximum transmission power a lower AMR bit rate can be used to extend the cell coverage area Adaptive multi-rate also contains error concealment The purpose of frame substitution is to conceal the effect of lost speech frames If several frames are lost muting is used to prevent possibly annoying sounds as a result of the frame substitution In P5 with AMR NB it is possible to use lower speech codec rates than 122 kbps The radio network also supports 795 kbps 59 kbps and 475 kbps AMR codecs There is no adaptation in the sense that AMR codecs are changed during an ongoing speech connection rather there is a possibility to adapt the rate at initial selection

23

Link Budget

bull Cell range amp cell capacity are limited by the same parameters

Interference in uplink

Power in downlink

bull Cell breathing phenomenon

ldquoPowerrdquo Link Budget

Tx power + All Gains ndash Path Loss ndash Other losses = Rx power

Path loss = Tx Signal + All Gains ndash Other losses ndash Rx power

Max Path loss = Tx Signal + All Gains ndash Other losses ndash Rx sensitivity

25

Initial Cell Search

The initial Cell Search is carried out in three steps

Step 1 Slot synchronisation - using the primary synchronisation channel

Step 2 Frame synchronisation and code-group identification- using the secondary synchronisation channel

Step 3 Scrambling-code identification-identified through symbol- by-symbol correlation over the primary CCPCH with all the scrambling codes within the code group

26

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

27

Frame Synchronization

helliphellip

2560 chips

acp

Slot

P-SCH acp

Slot

16 11 S-SCH

acp

Slot

2 Group 4 Slot 121314

slot number Scrambling Code Group 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Group 0 1 1 2 8 9 10 15 8 10 16 2 7 15 7 16

Group 1 1 1 5 16 7 3 14 16 3 10 5 12 14 12 10

Group 2 1 2 1 15 5 5 12 16 6 11 2 16 11 15 12

Group 3 1 2 3 1 8 6 5 2 5 8 4 4 6 3 7

Group 4 1 2 16 6 6 11 15 5 12 1 15 12 16 11 2

hellip

Group 61 9 10 13 10 11 15 15 9 16 12 14 13 16 14 11

Group 62 9 11 12 15 12 9 13 13 11 14 10 16 15 14 16

Group 63 9 12 10 15 13 14 9 14 15 11 11 13 12 16 10

256 chips

S-SCH

P-SCH

512 Primary Scrambling Codes divided into 64 groups

28

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

29

Cell Information

P-SCH Coverage indication Slot Synchronization

S-SCH Frame Synchronization Group identification

P-CPICH Scrambling Code Identification

P-CCPCH System Information Broadcast

Logical Channel

BCCH

Transport Channel

BCH

Physical Channel

P-CCPCH

OVSF Cch2561

Primary Scrambling Code

Transmitted during 910th slot

Bit Rate 123 kbps RLC Mode transparent

Mac-B transparent

30

Intra-Frequency Cell Reselection sample

Time

Quality

Serving CellServing Cell

Neighboring Cell

Neighboring Cell

Neighboring

cell criterion S

is fulfilled and is

ranked

Neighboring cell

better ranking

than Serving cell

UE perform cell

reselection

Treselections

Qmeans + Qhyst2s

Qmeann - Qoffset2sn

Qqualmin

UE perform

intra-frequency

measurements

Qqualmin +

SIntraSearch

31

Cell selection and reselection Cell Selection criteria

The cell selection criterion S is fulfilled when

where

Squal = Qqualmeas ndash Qqualmin

Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

Pcompensation ＝ max(UE_TXPWR_MAX_RACH ndash P_MAX 0)

for FDD cells Srxlev gt 0 AND Squal gt 0

for TDD cells Srxlev gt 0

for GSM cells Srxlev gt 0

32

Cell Selection Parameters

Parameter Object Range Default Value Recommended Value Class

qQualMin CellSelectionInfo Int [-240]

(dB)

-10 -16 C2

qRxLevMin CellSelectionInfo Int [-115-25]

Step = 2 (dBm)

-45 -115 C2

maxAllowedUlTxPower UlUsPowerConf Int [-5033]

(dBm)

33 33 C3

P_Max = maximum UE output power (dBm) according to its class

Power Class Maximum Output Power (dBm)

1 33

2 27

3 24

4 21

33

Cell Reselection Procedure

Squal

SintraSearch

SinterSearch

SinterRAT Measurement on

same frequency Measurement on

other frequencies Measurement on

other RAT

If Squal = CPICH_EcNo ndash qQualMin lt Threshold

Associated measurements are performed

Thresholds are broadcasted in SIB 11

In UMTS02 2 types of measurements are done Intra frequency and inter RAT

Th

rese

ho

lds

giv

en a

s ex

am

ple

34

Cell Reselection Parameters

Parameter Object Range Default Value Recommended Value Class

qHyst1 CellSelectionInfo Int [040] (dBm)

Step = 2

10 4 C2

qHyst2 CellSelectionInfo

Int [040] (dB)

Step = 2

4 6 C2

qOffset1sn GSMCell

Int [-5050] (dB) 0 TBD C0

qOffset2sn UMTSFDDNeighbouring Int [-5050] (dB) 0 TBD C0

qualMeas CPICH_EcNo or

CPICH_RSCP

CPICH_EcNo NA Static

tReselection CellSelectionInfo Int [031] (s) 31 6 C2

35

Measurements

The different types of air interface measurements are

bull Intra-frequency measurements measurements on downlink physical channels at the same frequency as the active set A measurement object corresponds to one cell

bull Inter-frequency measurements measurements on downlink physical channels at frequencies that differ from the frequency of the active set A measurement object corresponds to one cell

bull Inter-RAT measurements measurements on downlink physical channels belonging to another radio access technology than UTRAN eg GSM A measurement object corresponds to one cell

36

Handover (Handoff) bull There are following categories of handover (also referred to as handoff)

bull Hard handover means that all the old radio links in the UE are removed before

the new radio links are established Hard handover can be seamless or non-seamless Seamless hard handover means that the handover is not perceptible to the user In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover

bull Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN Soft handover is performed by means of macro diversity which refers to the condition that several radio links are active at the same time

bull Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (ie the site of co-located base stations from which several sector-cells are served

37

Handover (Handoff) bull The most obvious cause for performing a handover is that due to its movement a user

can be served in another cell more efficiently (like less power emission less interference) It may however also be performed for other reasons such as system load control

bull Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (ie the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set)

bull The maximum active set size at the RNC is determined by the parameter MaxAciveSetSize

bull 3 to 4 cells the larger the active set size the more likely it is that Iub link efficiency is reduced (more than one resource for a single connection due to SHO)

bull Cells which are not included in the active set but are included in the CELL_INFO_LIST belong to the Monitored Set

bull Cells detected by the UE which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state

38

PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)

bull The primary cell election algorithm applies to soft HO It is used for monitored set determination and a pointer to mobility parameter

bull The Monitored Set should be updated each time the primary cell of active set changes A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set The message contains the cell to addremove from the monitored and should follow the ACIVE SET UPDATE message

bull The primary cell algorithm is called from SHO algorithm therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC

Measurement control used for monitored set update

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

Pilot Pollution

Excessive strong pilots exist at a point but no one is strong enough to be primary pilot 1 Definition of strong pilot (CPICH_RSCP gt ThRSCP) 2 Definition of Excessive CPICH_Number gt ThN

3 Definition of no best server strong enoughrdquo CPICH_RSCP1st-CPICH_RSCP(ThN+1)th lt ThRSCP_Relative

Following is the case from cluster Mongkok West Probable Solution adjust engineering parameters of an antenna so that a best server forms around the antenna For handover problems caused by pilot pollution adjust engineering parameters of other antennas so that signals from other antennas becomes weaker and the number of pilots drops For this case reduce antenna height of site SGI Many definitions A cell that has a high signal strength at a location but is not part of the active set A cell that meets thecriteria for addition into the Active Set but can not enter because the active set is full

1UE fails to receive active set update command (Delayed Handover) After UE reports measurement message the EcIo of original cell signals decreases sharply When the RNC sends active set update message the UE powers off the transmitter due to asynchronization The UE cannot receive active set update message This may be due to EcIo of original cell decreases sharply and that of the target cell increases greatly (Turnings) 2 The best server changes frequently Two or more cells alternate to be the best server The RSCP of the best server is strong The period for each cell to be the best server is short Probable solution Lower the triggering time for event 1a adjust antennas to expand the handover area adjust the antenna to form a best server reduce Ping-pong handover by setting the handover parameter of 1B event

17

Radio Interface Protocol Architecture

Radio

Interface

Protocol

Architecture

Transport Channel (SAP)

Physical Channels

Logical Channel

L3

contr

ol

contr

ol

contr

ol

contr

ol

Logical

Channels

Transport

Channels

C-plane signalling U-plane information

PHY

L2MAC

L1

RLC

DCNtGC

L2RLC

MAC

RLC

RLCRLC

RLC

RLCRLC

RLC

Duplication avoidance

UuS boundary

BMC L2BMC

RRC

control

PDCPPDCP L2PDCP

DCNtGC

Packet Data Convergence Protocol

Is only for PS domain services

18

Radio Interface protocol architecture

L2MAC

L2RLC

L1

RLC

MAC

L3 RRC

PHY

Transport Channels

Logical Channels

C-plane signalling U-plane information

GC Nt DC

RLC RLC

RLC

GC NT DC RRC RLC MAC

General Control Notification Dedicated Control Radio Resource Control Radio Link Control Medium Access Control

UTRA Protocol Architecture

19

Logical Channel Structure

Synchronisation Control Channel (SCCH)

Broadcast Control Channel (BCCH)

Paging Control Channel (PCCH)

Dedicated Control Channel (DCCH)

Dedicated Control Channel (DCCH)Common Control Channel (CCCH)

Control Channel (CCH)

Dedicated Traffic Channel (DTCH)Traffic Channel (TCH)

ODMA Dedicated Control Channel (ODCCH)

ODMA Common Control Channel (OCCCH)

ODMA Dedicated Traffic Channel (ODTCH)

Common Traffic Channel (CTCH)

Shared Channel Control Channel (SHCCH)

(TDD)

(ODMA)

(ODMA)

(TDD)

20

Channels

Transport Channels Dedicated Transport Channel (DCH) ULDL mapped to DCCH and DTCH Broadcast Channel (BCH) DL mapped to BCCH Forward Access Channel (FACH) DL mapped to BCCH CCCH CTCH DCCH and DTCH Paging Channel (PCH) DL mapped to PCCH Random Access Channel (RACH) UL mapped to CCCH DCCH and DTCH Uplink Common Packet Channel (CPCH) UL mapped to DCCH and DTCH Downlink Shared Channel (DSCH) DL mapped to DCCH and DTCH The speech service in UMTS will employ the Adaptive Multi - rate technique 1048707 This is a single integrated codec with eight source rates 122 102 795 740 670 590 515 and 475 kbps To facilitate interoperability with existing cellular networks some of the modes are the same as in existing networks

21

Channels Physical Channels Primary Common Control Physical Channel (PCCPCH) mapped to BCH Secondary Common Control Physical Channel (SCCPCH) mapped to FACH PCH Physical Random Access Channel (PRACH) mapped to RACH Dedicated Physical Data Channel (DPDCH) mapped to DCH Dedicated Physical Control Channel (DPCCH) mapped to DCH Physical Downlink Shared Channel (PDSCH) mapped to DSCH Physical Common Packet Channel (PCPCH) mapped to CPCH Synchronisation Channel (SCH) Common Pilot Channel (CPICH) Acquisition Indicator Channel (AICH) Paging Indication Channel (PICH) CPCH Status Indication Channel (CSICH) Collision DetectionChannel Assignment Indication Channel (CDCA-ICH)

AMR

The bit rate of the AMR speech connection is controlled by the radio access network depending on the air interface loading and the quality of the speech connections During high loading such as during busy hours it is possible to use lower AMR bit rates to offer higher capacity while providing slightly lower speech quality Also if the mobile is running out of the cell coverage area and using its maximum transmission power a lower AMR bit rate can be used to extend the cell coverage area Adaptive multi-rate also contains error concealment The purpose of frame substitution is to conceal the effect of lost speech frames If several frames are lost muting is used to prevent possibly annoying sounds as a result of the frame substitution In P5 with AMR NB it is possible to use lower speech codec rates than 122 kbps The radio network also supports 795 kbps 59 kbps and 475 kbps AMR codecs There is no adaptation in the sense that AMR codecs are changed during an ongoing speech connection rather there is a possibility to adapt the rate at initial selection

23

Link Budget

bull Cell range amp cell capacity are limited by the same parameters

Interference in uplink

Power in downlink

bull Cell breathing phenomenon

ldquoPowerrdquo Link Budget

Tx power + All Gains ndash Path Loss ndash Other losses = Rx power

Path loss = Tx Signal + All Gains ndash Other losses ndash Rx power

Max Path loss = Tx Signal + All Gains ndash Other losses ndash Rx sensitivity

25

Initial Cell Search

The initial Cell Search is carried out in three steps

Step 1 Slot synchronisation - using the primary synchronisation channel

Step 2 Frame synchronisation and code-group identification- using the secondary synchronisation channel

Step 3 Scrambling-code identification-identified through symbol- by-symbol correlation over the primary CCPCH with all the scrambling codes within the code group

26

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

27

Frame Synchronization

helliphellip

2560 chips

acp

Slot

P-SCH acp

Slot

16 11 S-SCH

acp

Slot

2 Group 4 Slot 121314

slot number Scrambling Code Group 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Group 0 1 1 2 8 9 10 15 8 10 16 2 7 15 7 16

Group 1 1 1 5 16 7 3 14 16 3 10 5 12 14 12 10

Group 2 1 2 1 15 5 5 12 16 6 11 2 16 11 15 12

Group 3 1 2 3 1 8 6 5 2 5 8 4 4 6 3 7

Group 4 1 2 16 6 6 11 15 5 12 1 15 12 16 11 2

hellip

Group 61 9 10 13 10 11 15 15 9 16 12 14 13 16 14 11

Group 62 9 11 12 15 12 9 13 13 11 14 10 16 15 14 16

Group 63 9 12 10 15 13 14 9 14 15 11 11 13 12 16 10

256 chips

S-SCH

P-SCH

512 Primary Scrambling Codes divided into 64 groups

28

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

29

Cell Information

P-SCH Coverage indication Slot Synchronization

S-SCH Frame Synchronization Group identification

P-CPICH Scrambling Code Identification

P-CCPCH System Information Broadcast

Logical Channel

BCCH

Transport Channel

BCH

Physical Channel

P-CCPCH

OVSF Cch2561

Primary Scrambling Code

Transmitted during 910th slot

Bit Rate 123 kbps RLC Mode transparent

Mac-B transparent

30

Intra-Frequency Cell Reselection sample

Time

Quality

Serving CellServing Cell

Neighboring Cell

Neighboring Cell

Neighboring

cell criterion S

is fulfilled and is

ranked

Neighboring cell

better ranking

than Serving cell

UE perform cell

reselection

Treselections

Qmeans + Qhyst2s

Qmeann - Qoffset2sn

Qqualmin

UE perform

intra-frequency

measurements

Qqualmin +

SIntraSearch

31

Cell selection and reselection Cell Selection criteria

The cell selection criterion S is fulfilled when

where

Squal = Qqualmeas ndash Qqualmin

Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

Pcompensation ＝ max(UE_TXPWR_MAX_RACH ndash P_MAX 0)

for FDD cells Srxlev gt 0 AND Squal gt 0

for TDD cells Srxlev gt 0

for GSM cells Srxlev gt 0

32

Cell Selection Parameters

Parameter Object Range Default Value Recommended Value Class

qQualMin CellSelectionInfo Int [-240]

(dB)

-10 -16 C2

qRxLevMin CellSelectionInfo Int [-115-25]

Step = 2 (dBm)

-45 -115 C2

maxAllowedUlTxPower UlUsPowerConf Int [-5033]

(dBm)

33 33 C3

P_Max = maximum UE output power (dBm) according to its class

Power Class Maximum Output Power (dBm)

1 33

2 27

3 24

4 21

33

Cell Reselection Procedure

Squal

SintraSearch

SinterSearch

SinterRAT Measurement on

same frequency Measurement on

other frequencies Measurement on

other RAT

If Squal = CPICH_EcNo ndash qQualMin lt Threshold

Associated measurements are performed

Thresholds are broadcasted in SIB 11

In UMTS02 2 types of measurements are done Intra frequency and inter RAT

Th

rese

ho

lds

giv

en a

s ex

am

ple

34

Cell Reselection Parameters

Parameter Object Range Default Value Recommended Value Class

qHyst1 CellSelectionInfo Int [040] (dBm)

Step = 2

10 4 C2

qHyst2 CellSelectionInfo

Int [040] (dB)

Step = 2

4 6 C2

qOffset1sn GSMCell

Int [-5050] (dB) 0 TBD C0

qOffset2sn UMTSFDDNeighbouring Int [-5050] (dB) 0 TBD C0

qualMeas CPICH_EcNo or

CPICH_RSCP

CPICH_EcNo NA Static

tReselection CellSelectionInfo Int [031] (s) 31 6 C2

35

Measurements

The different types of air interface measurements are

bull Intra-frequency measurements measurements on downlink physical channels at the same frequency as the active set A measurement object corresponds to one cell

bull Inter-frequency measurements measurements on downlink physical channels at frequencies that differ from the frequency of the active set A measurement object corresponds to one cell

bull Inter-RAT measurements measurements on downlink physical channels belonging to another radio access technology than UTRAN eg GSM A measurement object corresponds to one cell

36

Handover (Handoff) bull There are following categories of handover (also referred to as handoff)

bull Hard handover means that all the old radio links in the UE are removed before

the new radio links are established Hard handover can be seamless or non-seamless Seamless hard handover means that the handover is not perceptible to the user In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover

bull Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN Soft handover is performed by means of macro diversity which refers to the condition that several radio links are active at the same time

bull Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (ie the site of co-located base stations from which several sector-cells are served

37

Handover (Handoff) bull The most obvious cause for performing a handover is that due to its movement a user

can be served in another cell more efficiently (like less power emission less interference) It may however also be performed for other reasons such as system load control

bull Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (ie the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set)

bull The maximum active set size at the RNC is determined by the parameter MaxAciveSetSize

bull 3 to 4 cells the larger the active set size the more likely it is that Iub link efficiency is reduced (more than one resource for a single connection due to SHO)

bull Cells which are not included in the active set but are included in the CELL_INFO_LIST belong to the Monitored Set

bull Cells detected by the UE which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state

38

PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)

bull The primary cell election algorithm applies to soft HO It is used for monitored set determination and a pointer to mobility parameter

bull The Monitored Set should be updated each time the primary cell of active set changes A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set The message contains the cell to addremove from the monitored and should follow the ACIVE SET UPDATE message

bull The primary cell algorithm is called from SHO algorithm therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC

Measurement control used for monitored set update

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

1UE fails to receive active set update command (Delayed Handover) After UE reports measurement message the EcIo of original cell signals decreases sharply When the RNC sends active set update message the UE powers off the transmitter due to asynchronization The UE cannot receive active set update message This may be due to EcIo of original cell decreases sharply and that of the target cell increases greatly (Turnings) 2 The best server changes frequently Two or more cells alternate to be the best server The RSCP of the best server is strong The period for each cell to be the best server is short Probable solution Lower the triggering time for event 1a adjust antennas to expand the handover area adjust the antenna to form a best server reduce Ping-pong handover by setting the handover parameter of 1B event

17

Radio Interface Protocol Architecture

Radio

Interface

Protocol

Architecture

Transport Channel (SAP)

Physical Channels

Logical Channel

L3

contr

ol

contr

ol

contr

ol

contr

ol

Logical

Channels

Transport

Channels

C-plane signalling U-plane information

PHY

L2MAC

L1

RLC

DCNtGC

L2RLC

MAC

RLC

RLCRLC

RLC

RLCRLC

RLC

Duplication avoidance

UuS boundary

BMC L2BMC

RRC

control

PDCPPDCP L2PDCP

DCNtGC

Packet Data Convergence Protocol

Is only for PS domain services

18

Radio Interface protocol architecture

L2MAC

L2RLC

L1

RLC

MAC

L3 RRC

PHY

Transport Channels

Logical Channels

C-plane signalling U-plane information

GC Nt DC

RLC RLC

RLC

GC NT DC RRC RLC MAC

General Control Notification Dedicated Control Radio Resource Control Radio Link Control Medium Access Control

UTRA Protocol Architecture

19

Logical Channel Structure

Synchronisation Control Channel (SCCH)

Broadcast Control Channel (BCCH)

Paging Control Channel (PCCH)

Dedicated Control Channel (DCCH)

Dedicated Control Channel (DCCH)Common Control Channel (CCCH)

Control Channel (CCH)

Dedicated Traffic Channel (DTCH)Traffic Channel (TCH)

ODMA Dedicated Control Channel (ODCCH)

ODMA Common Control Channel (OCCCH)

ODMA Dedicated Traffic Channel (ODTCH)

Common Traffic Channel (CTCH)

Shared Channel Control Channel (SHCCH)

(TDD)

(ODMA)

(ODMA)

(TDD)

20

Channels

Transport Channels Dedicated Transport Channel (DCH) ULDL mapped to DCCH and DTCH Broadcast Channel (BCH) DL mapped to BCCH Forward Access Channel (FACH) DL mapped to BCCH CCCH CTCH DCCH and DTCH Paging Channel (PCH) DL mapped to PCCH Random Access Channel (RACH) UL mapped to CCCH DCCH and DTCH Uplink Common Packet Channel (CPCH) UL mapped to DCCH and DTCH Downlink Shared Channel (DSCH) DL mapped to DCCH and DTCH The speech service in UMTS will employ the Adaptive Multi - rate technique 1048707 This is a single integrated codec with eight source rates 122 102 795 740 670 590 515 and 475 kbps To facilitate interoperability with existing cellular networks some of the modes are the same as in existing networks

21

Channels Physical Channels Primary Common Control Physical Channel (PCCPCH) mapped to BCH Secondary Common Control Physical Channel (SCCPCH) mapped to FACH PCH Physical Random Access Channel (PRACH) mapped to RACH Dedicated Physical Data Channel (DPDCH) mapped to DCH Dedicated Physical Control Channel (DPCCH) mapped to DCH Physical Downlink Shared Channel (PDSCH) mapped to DSCH Physical Common Packet Channel (PCPCH) mapped to CPCH Synchronisation Channel (SCH) Common Pilot Channel (CPICH) Acquisition Indicator Channel (AICH) Paging Indication Channel (PICH) CPCH Status Indication Channel (CSICH) Collision DetectionChannel Assignment Indication Channel (CDCA-ICH)

AMR

The bit rate of the AMR speech connection is controlled by the radio access network depending on the air interface loading and the quality of the speech connections During high loading such as during busy hours it is possible to use lower AMR bit rates to offer higher capacity while providing slightly lower speech quality Also if the mobile is running out of the cell coverage area and using its maximum transmission power a lower AMR bit rate can be used to extend the cell coverage area Adaptive multi-rate also contains error concealment The purpose of frame substitution is to conceal the effect of lost speech frames If several frames are lost muting is used to prevent possibly annoying sounds as a result of the frame substitution In P5 with AMR NB it is possible to use lower speech codec rates than 122 kbps The radio network also supports 795 kbps 59 kbps and 475 kbps AMR codecs There is no adaptation in the sense that AMR codecs are changed during an ongoing speech connection rather there is a possibility to adapt the rate at initial selection

23

Link Budget

bull Cell range amp cell capacity are limited by the same parameters

Interference in uplink

Power in downlink

bull Cell breathing phenomenon

ldquoPowerrdquo Link Budget

Tx power + All Gains ndash Path Loss ndash Other losses = Rx power

Path loss = Tx Signal + All Gains ndash Other losses ndash Rx power

Max Path loss = Tx Signal + All Gains ndash Other losses ndash Rx sensitivity

25

Initial Cell Search

The initial Cell Search is carried out in three steps

Step 1 Slot synchronisation - using the primary synchronisation channel

Step 2 Frame synchronisation and code-group identification- using the secondary synchronisation channel

Step 3 Scrambling-code identification-identified through symbol- by-symbol correlation over the primary CCPCH with all the scrambling codes within the code group

26

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

27

Frame Synchronization

helliphellip

2560 chips

acp

Slot

P-SCH acp

Slot

16 11 S-SCH

acp

Slot

2 Group 4 Slot 121314

slot number Scrambling Code Group 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Group 0 1 1 2 8 9 10 15 8 10 16 2 7 15 7 16

Group 1 1 1 5 16 7 3 14 16 3 10 5 12 14 12 10

Group 2 1 2 1 15 5 5 12 16 6 11 2 16 11 15 12

Group 3 1 2 3 1 8 6 5 2 5 8 4 4 6 3 7

Group 4 1 2 16 6 6 11 15 5 12 1 15 12 16 11 2

hellip

Group 61 9 10 13 10 11 15 15 9 16 12 14 13 16 14 11

Group 62 9 11 12 15 12 9 13 13 11 14 10 16 15 14 16

Group 63 9 12 10 15 13 14 9 14 15 11 11 13 12 16 10

256 chips

S-SCH

P-SCH

512 Primary Scrambling Codes divided into 64 groups

28

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

29

Cell Information

P-SCH Coverage indication Slot Synchronization

S-SCH Frame Synchronization Group identification

P-CPICH Scrambling Code Identification

P-CCPCH System Information Broadcast

Logical Channel

BCCH

Transport Channel

BCH

Physical Channel

P-CCPCH

OVSF Cch2561

Primary Scrambling Code

Transmitted during 910th slot

Bit Rate 123 kbps RLC Mode transparent

Mac-B transparent

30

Intra-Frequency Cell Reselection sample

Time

Quality

Serving CellServing Cell

Neighboring Cell

Neighboring Cell

Neighboring

cell criterion S

is fulfilled and is

ranked

Neighboring cell

better ranking

than Serving cell

UE perform cell

reselection

Treselections

Qmeans + Qhyst2s

Qmeann - Qoffset2sn

Qqualmin

UE perform

intra-frequency

measurements

Qqualmin +

SIntraSearch

31

Cell selection and reselection Cell Selection criteria

The cell selection criterion S is fulfilled when

where

Squal = Qqualmeas ndash Qqualmin

Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

Pcompensation ＝ max(UE_TXPWR_MAX_RACH ndash P_MAX 0)

for FDD cells Srxlev gt 0 AND Squal gt 0

for TDD cells Srxlev gt 0

for GSM cells Srxlev gt 0

32

Cell Selection Parameters

Parameter Object Range Default Value Recommended Value Class

qQualMin CellSelectionInfo Int [-240]

(dB)

-10 -16 C2

qRxLevMin CellSelectionInfo Int [-115-25]

Step = 2 (dBm)

-45 -115 C2

maxAllowedUlTxPower UlUsPowerConf Int [-5033]

(dBm)

33 33 C3

P_Max = maximum UE output power (dBm) according to its class

Power Class Maximum Output Power (dBm)

1 33

2 27

3 24

4 21

33

Cell Reselection Procedure

Squal

SintraSearch

SinterSearch

SinterRAT Measurement on

same frequency Measurement on

other frequencies Measurement on

other RAT

If Squal = CPICH_EcNo ndash qQualMin lt Threshold

Associated measurements are performed

Thresholds are broadcasted in SIB 11

In UMTS02 2 types of measurements are done Intra frequency and inter RAT

Th

rese

ho

lds

giv

en a

s ex

am

ple

34

Cell Reselection Parameters

Parameter Object Range Default Value Recommended Value Class

qHyst1 CellSelectionInfo Int [040] (dBm)

Step = 2

10 4 C2

qHyst2 CellSelectionInfo

Int [040] (dB)

Step = 2

4 6 C2

qOffset1sn GSMCell

Int [-5050] (dB) 0 TBD C0

qOffset2sn UMTSFDDNeighbouring Int [-5050] (dB) 0 TBD C0

qualMeas CPICH_EcNo or

CPICH_RSCP

CPICH_EcNo NA Static

tReselection CellSelectionInfo Int [031] (s) 31 6 C2

35

Measurements

The different types of air interface measurements are

bull Intra-frequency measurements measurements on downlink physical channels at the same frequency as the active set A measurement object corresponds to one cell

bull Inter-frequency measurements measurements on downlink physical channels at frequencies that differ from the frequency of the active set A measurement object corresponds to one cell

bull Inter-RAT measurements measurements on downlink physical channels belonging to another radio access technology than UTRAN eg GSM A measurement object corresponds to one cell

36

Handover (Handoff) bull There are following categories of handover (also referred to as handoff)

bull Hard handover means that all the old radio links in the UE are removed before

the new radio links are established Hard handover can be seamless or non-seamless Seamless hard handover means that the handover is not perceptible to the user In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover

bull Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN Soft handover is performed by means of macro diversity which refers to the condition that several radio links are active at the same time

bull Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (ie the site of co-located base stations from which several sector-cells are served

37

Handover (Handoff) bull The most obvious cause for performing a handover is that due to its movement a user

can be served in another cell more efficiently (like less power emission less interference) It may however also be performed for other reasons such as system load control

bull Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (ie the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set)

bull The maximum active set size at the RNC is determined by the parameter MaxAciveSetSize

bull 3 to 4 cells the larger the active set size the more likely it is that Iub link efficiency is reduced (more than one resource for a single connection due to SHO)

bull Cells which are not included in the active set but are included in the CELL_INFO_LIST belong to the Monitored Set

bull Cells detected by the UE which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state

38

PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)

bull The primary cell election algorithm applies to soft HO It is used for monitored set determination and a pointer to mobility parameter

bull The Monitored Set should be updated each time the primary cell of active set changes A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set The message contains the cell to addremove from the monitored and should follow the ACIVE SET UPDATE message

bull The primary cell algorithm is called from SHO algorithm therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC

Measurement control used for monitored set update

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

17

Radio Interface Protocol Architecture

Radio

Interface

Protocol

Architecture

Transport Channel (SAP)

Physical Channels

Logical Channel

L3

contr

ol

contr

ol

contr

ol

contr

ol

Logical

Channels

Transport

Channels

C-plane signalling U-plane information

PHY

L2MAC

L1

RLC

DCNtGC

L2RLC

MAC

RLC

RLCRLC

RLC

RLCRLC

RLC

Duplication avoidance

UuS boundary

BMC L2BMC

RRC

control

PDCPPDCP L2PDCP

DCNtGC

Packet Data Convergence Protocol

Is only for PS domain services

18

Radio Interface protocol architecture

L2MAC

L2RLC

L1

RLC

MAC

L3 RRC

PHY

Transport Channels

Logical Channels

C-plane signalling U-plane information

GC Nt DC

RLC RLC

RLC

GC NT DC RRC RLC MAC

General Control Notification Dedicated Control Radio Resource Control Radio Link Control Medium Access Control

UTRA Protocol Architecture

19

Logical Channel Structure

Synchronisation Control Channel (SCCH)

Broadcast Control Channel (BCCH)

Paging Control Channel (PCCH)

Dedicated Control Channel (DCCH)

Dedicated Control Channel (DCCH)Common Control Channel (CCCH)

Control Channel (CCH)

Dedicated Traffic Channel (DTCH)Traffic Channel (TCH)

ODMA Dedicated Control Channel (ODCCH)

ODMA Common Control Channel (OCCCH)

ODMA Dedicated Traffic Channel (ODTCH)

Common Traffic Channel (CTCH)

Shared Channel Control Channel (SHCCH)

(TDD)

(ODMA)

(ODMA)

(TDD)

20

Channels

Transport Channels Dedicated Transport Channel (DCH) ULDL mapped to DCCH and DTCH Broadcast Channel (BCH) DL mapped to BCCH Forward Access Channel (FACH) DL mapped to BCCH CCCH CTCH DCCH and DTCH Paging Channel (PCH) DL mapped to PCCH Random Access Channel (RACH) UL mapped to CCCH DCCH and DTCH Uplink Common Packet Channel (CPCH) UL mapped to DCCH and DTCH Downlink Shared Channel (DSCH) DL mapped to DCCH and DTCH The speech service in UMTS will employ the Adaptive Multi - rate technique 1048707 This is a single integrated codec with eight source rates 122 102 795 740 670 590 515 and 475 kbps To facilitate interoperability with existing cellular networks some of the modes are the same as in existing networks

21

Channels Physical Channels Primary Common Control Physical Channel (PCCPCH) mapped to BCH Secondary Common Control Physical Channel (SCCPCH) mapped to FACH PCH Physical Random Access Channel (PRACH) mapped to RACH Dedicated Physical Data Channel (DPDCH) mapped to DCH Dedicated Physical Control Channel (DPCCH) mapped to DCH Physical Downlink Shared Channel (PDSCH) mapped to DSCH Physical Common Packet Channel (PCPCH) mapped to CPCH Synchronisation Channel (SCH) Common Pilot Channel (CPICH) Acquisition Indicator Channel (AICH) Paging Indication Channel (PICH) CPCH Status Indication Channel (CSICH) Collision DetectionChannel Assignment Indication Channel (CDCA-ICH)

AMR

The bit rate of the AMR speech connection is controlled by the radio access network depending on the air interface loading and the quality of the speech connections During high loading such as during busy hours it is possible to use lower AMR bit rates to offer higher capacity while providing slightly lower speech quality Also if the mobile is running out of the cell coverage area and using its maximum transmission power a lower AMR bit rate can be used to extend the cell coverage area Adaptive multi-rate also contains error concealment The purpose of frame substitution is to conceal the effect of lost speech frames If several frames are lost muting is used to prevent possibly annoying sounds as a result of the frame substitution In P5 with AMR NB it is possible to use lower speech codec rates than 122 kbps The radio network also supports 795 kbps 59 kbps and 475 kbps AMR codecs There is no adaptation in the sense that AMR codecs are changed during an ongoing speech connection rather there is a possibility to adapt the rate at initial selection

23

Link Budget

bull Cell range amp cell capacity are limited by the same parameters

Interference in uplink

Power in downlink

bull Cell breathing phenomenon

ldquoPowerrdquo Link Budget

Tx power + All Gains ndash Path Loss ndash Other losses = Rx power

Path loss = Tx Signal + All Gains ndash Other losses ndash Rx power

Max Path loss = Tx Signal + All Gains ndash Other losses ndash Rx sensitivity

25

Initial Cell Search

The initial Cell Search is carried out in three steps

Step 1 Slot synchronisation - using the primary synchronisation channel

Step 2 Frame synchronisation and code-group identification- using the secondary synchronisation channel

Step 3 Scrambling-code identification-identified through symbol- by-symbol correlation over the primary CCPCH with all the scrambling codes within the code group

26

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

27

Frame Synchronization

helliphellip

2560 chips

acp

Slot

P-SCH acp

Slot

16 11 S-SCH

acp

Slot

2 Group 4 Slot 121314

slot number Scrambling Code Group 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Group 0 1 1 2 8 9 10 15 8 10 16 2 7 15 7 16

Group 1 1 1 5 16 7 3 14 16 3 10 5 12 14 12 10

Group 2 1 2 1 15 5 5 12 16 6 11 2 16 11 15 12

Group 3 1 2 3 1 8 6 5 2 5 8 4 4 6 3 7

Group 4 1 2 16 6 6 11 15 5 12 1 15 12 16 11 2

hellip

Group 61 9 10 13 10 11 15 15 9 16 12 14 13 16 14 11

Group 62 9 11 12 15 12 9 13 13 11 14 10 16 15 14 16

Group 63 9 12 10 15 13 14 9 14 15 11 11 13 12 16 10

256 chips

S-SCH

P-SCH

512 Primary Scrambling Codes divided into 64 groups

28

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

29

Cell Information

P-SCH Coverage indication Slot Synchronization

S-SCH Frame Synchronization Group identification

P-CPICH Scrambling Code Identification

P-CCPCH System Information Broadcast

Logical Channel

BCCH

Transport Channel

BCH

Physical Channel

P-CCPCH

OVSF Cch2561

Primary Scrambling Code

Transmitted during 910th slot

Bit Rate 123 kbps RLC Mode transparent

Mac-B transparent

30

Intra-Frequency Cell Reselection sample

Time

Quality

Serving CellServing Cell

Neighboring Cell

Neighboring Cell

Neighboring

cell criterion S

is fulfilled and is

ranked

Neighboring cell

better ranking

than Serving cell

UE perform cell

reselection

Treselections

Qmeans + Qhyst2s

Qmeann - Qoffset2sn

Qqualmin

UE perform

intra-frequency

measurements

Qqualmin +

SIntraSearch

31

Cell selection and reselection Cell Selection criteria

The cell selection criterion S is fulfilled when

where

Squal = Qqualmeas ndash Qqualmin

Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

Pcompensation ＝ max(UE_TXPWR_MAX_RACH ndash P_MAX 0)

for FDD cells Srxlev gt 0 AND Squal gt 0

for TDD cells Srxlev gt 0

for GSM cells Srxlev gt 0

32

Cell Selection Parameters

Parameter Object Range Default Value Recommended Value Class

qQualMin CellSelectionInfo Int [-240]

(dB)

-10 -16 C2

qRxLevMin CellSelectionInfo Int [-115-25]

Step = 2 (dBm)

-45 -115 C2

maxAllowedUlTxPower UlUsPowerConf Int [-5033]

(dBm)

33 33 C3

P_Max = maximum UE output power (dBm) according to its class

Power Class Maximum Output Power (dBm)

1 33

2 27

3 24

4 21

33

Cell Reselection Procedure

Squal

SintraSearch

SinterSearch

SinterRAT Measurement on

same frequency Measurement on

other frequencies Measurement on

other RAT

If Squal = CPICH_EcNo ndash qQualMin lt Threshold

Associated measurements are performed

Thresholds are broadcasted in SIB 11

In UMTS02 2 types of measurements are done Intra frequency and inter RAT

Th

rese

ho

lds

giv

en a

s ex

am

ple

34

Cell Reselection Parameters

Parameter Object Range Default Value Recommended Value Class

qHyst1 CellSelectionInfo Int [040] (dBm)

Step = 2

10 4 C2

qHyst2 CellSelectionInfo

Int [040] (dB)

Step = 2

4 6 C2

qOffset1sn GSMCell

Int [-5050] (dB) 0 TBD C0

qOffset2sn UMTSFDDNeighbouring Int [-5050] (dB) 0 TBD C0

qualMeas CPICH_EcNo or

CPICH_RSCP

CPICH_EcNo NA Static

tReselection CellSelectionInfo Int [031] (s) 31 6 C2

35

Measurements

The different types of air interface measurements are

bull Intra-frequency measurements measurements on downlink physical channels at the same frequency as the active set A measurement object corresponds to one cell

bull Inter-frequency measurements measurements on downlink physical channels at frequencies that differ from the frequency of the active set A measurement object corresponds to one cell

bull Inter-RAT measurements measurements on downlink physical channels belonging to another radio access technology than UTRAN eg GSM A measurement object corresponds to one cell

36

Handover (Handoff) bull There are following categories of handover (also referred to as handoff)

bull Hard handover means that all the old radio links in the UE are removed before

the new radio links are established Hard handover can be seamless or non-seamless Seamless hard handover means that the handover is not perceptible to the user In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover

bull Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN Soft handover is performed by means of macro diversity which refers to the condition that several radio links are active at the same time

bull Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (ie the site of co-located base stations from which several sector-cells are served

37

Handover (Handoff) bull The most obvious cause for performing a handover is that due to its movement a user

can be served in another cell more efficiently (like less power emission less interference) It may however also be performed for other reasons such as system load control

bull Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (ie the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set)

bull The maximum active set size at the RNC is determined by the parameter MaxAciveSetSize

bull 3 to 4 cells the larger the active set size the more likely it is that Iub link efficiency is reduced (more than one resource for a single connection due to SHO)

bull Cells which are not included in the active set but are included in the CELL_INFO_LIST belong to the Monitored Set

bull Cells detected by the UE which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state

38

PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)

bull The primary cell election algorithm applies to soft HO It is used for monitored set determination and a pointer to mobility parameter

bull The Monitored Set should be updated each time the primary cell of active set changes A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set The message contains the cell to addremove from the monitored and should follow the ACIVE SET UPDATE message

bull The primary cell algorithm is called from SHO algorithm therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC

Measurement control used for monitored set update

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

18

Radio Interface protocol architecture

L2MAC

L2RLC

L1

RLC

MAC

L3 RRC

PHY

Transport Channels

Logical Channels

C-plane signalling U-plane information

GC Nt DC

RLC RLC

RLC

GC NT DC RRC RLC MAC

General Control Notification Dedicated Control Radio Resource Control Radio Link Control Medium Access Control

UTRA Protocol Architecture

19

Logical Channel Structure

Synchronisation Control Channel (SCCH)

Broadcast Control Channel (BCCH)

Paging Control Channel (PCCH)

Dedicated Control Channel (DCCH)

Dedicated Control Channel (DCCH)Common Control Channel (CCCH)

Control Channel (CCH)

Dedicated Traffic Channel (DTCH)Traffic Channel (TCH)

ODMA Dedicated Control Channel (ODCCH)

ODMA Common Control Channel (OCCCH)

ODMA Dedicated Traffic Channel (ODTCH)

Common Traffic Channel (CTCH)

Shared Channel Control Channel (SHCCH)

(TDD)

(ODMA)

(ODMA)

(TDD)

20

Channels

Transport Channels Dedicated Transport Channel (DCH) ULDL mapped to DCCH and DTCH Broadcast Channel (BCH) DL mapped to BCCH Forward Access Channel (FACH) DL mapped to BCCH CCCH CTCH DCCH and DTCH Paging Channel (PCH) DL mapped to PCCH Random Access Channel (RACH) UL mapped to CCCH DCCH and DTCH Uplink Common Packet Channel (CPCH) UL mapped to DCCH and DTCH Downlink Shared Channel (DSCH) DL mapped to DCCH and DTCH The speech service in UMTS will employ the Adaptive Multi - rate technique 1048707 This is a single integrated codec with eight source rates 122 102 795 740 670 590 515 and 475 kbps To facilitate interoperability with existing cellular networks some of the modes are the same as in existing networks

21

Channels Physical Channels Primary Common Control Physical Channel (PCCPCH) mapped to BCH Secondary Common Control Physical Channel (SCCPCH) mapped to FACH PCH Physical Random Access Channel (PRACH) mapped to RACH Dedicated Physical Data Channel (DPDCH) mapped to DCH Dedicated Physical Control Channel (DPCCH) mapped to DCH Physical Downlink Shared Channel (PDSCH) mapped to DSCH Physical Common Packet Channel (PCPCH) mapped to CPCH Synchronisation Channel (SCH) Common Pilot Channel (CPICH) Acquisition Indicator Channel (AICH) Paging Indication Channel (PICH) CPCH Status Indication Channel (CSICH) Collision DetectionChannel Assignment Indication Channel (CDCA-ICH)

AMR

The bit rate of the AMR speech connection is controlled by the radio access network depending on the air interface loading and the quality of the speech connections During high loading such as during busy hours it is possible to use lower AMR bit rates to offer higher capacity while providing slightly lower speech quality Also if the mobile is running out of the cell coverage area and using its maximum transmission power a lower AMR bit rate can be used to extend the cell coverage area Adaptive multi-rate also contains error concealment The purpose of frame substitution is to conceal the effect of lost speech frames If several frames are lost muting is used to prevent possibly annoying sounds as a result of the frame substitution In P5 with AMR NB it is possible to use lower speech codec rates than 122 kbps The radio network also supports 795 kbps 59 kbps and 475 kbps AMR codecs There is no adaptation in the sense that AMR codecs are changed during an ongoing speech connection rather there is a possibility to adapt the rate at initial selection

23

Link Budget

bull Cell range amp cell capacity are limited by the same parameters

Interference in uplink

Power in downlink

bull Cell breathing phenomenon

ldquoPowerrdquo Link Budget

Tx power + All Gains ndash Path Loss ndash Other losses = Rx power

Path loss = Tx Signal + All Gains ndash Other losses ndash Rx power

Max Path loss = Tx Signal + All Gains ndash Other losses ndash Rx sensitivity

25

Initial Cell Search

The initial Cell Search is carried out in three steps

Step 1 Slot synchronisation - using the primary synchronisation channel

Step 2 Frame synchronisation and code-group identification- using the secondary synchronisation channel

Step 3 Scrambling-code identification-identified through symbol- by-symbol correlation over the primary CCPCH with all the scrambling codes within the code group

26

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

27

Frame Synchronization

helliphellip

2560 chips

acp

Slot

P-SCH acp

Slot

16 11 S-SCH

acp

Slot

2 Group 4 Slot 121314

slot number Scrambling Code Group 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Group 0 1 1 2 8 9 10 15 8 10 16 2 7 15 7 16

Group 1 1 1 5 16 7 3 14 16 3 10 5 12 14 12 10

Group 2 1 2 1 15 5 5 12 16 6 11 2 16 11 15 12

Group 3 1 2 3 1 8 6 5 2 5 8 4 4 6 3 7

Group 4 1 2 16 6 6 11 15 5 12 1 15 12 16 11 2

hellip

Group 61 9 10 13 10 11 15 15 9 16 12 14 13 16 14 11

Group 62 9 11 12 15 12 9 13 13 11 14 10 16 15 14 16

Group 63 9 12 10 15 13 14 9 14 15 11 11 13 12 16 10

256 chips

S-SCH

P-SCH

512 Primary Scrambling Codes divided into 64 groups

28

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

29

Cell Information

P-SCH Coverage indication Slot Synchronization

S-SCH Frame Synchronization Group identification

P-CPICH Scrambling Code Identification

P-CCPCH System Information Broadcast

Logical Channel

BCCH

Transport Channel

BCH

Physical Channel

P-CCPCH

OVSF Cch2561

Primary Scrambling Code

Transmitted during 910th slot

Bit Rate 123 kbps RLC Mode transparent

Mac-B transparent

30

Intra-Frequency Cell Reselection sample

Time

Quality

Serving CellServing Cell

Neighboring Cell

Neighboring Cell

Neighboring

cell criterion S

is fulfilled and is

ranked

Neighboring cell

better ranking

than Serving cell

UE perform cell

reselection

Treselections

Qmeans + Qhyst2s

Qmeann - Qoffset2sn

Qqualmin

UE perform

intra-frequency

measurements

Qqualmin +

SIntraSearch

31

Cell selection and reselection Cell Selection criteria

The cell selection criterion S is fulfilled when

where

Squal = Qqualmeas ndash Qqualmin

Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

Pcompensation ＝ max(UE_TXPWR_MAX_RACH ndash P_MAX 0)

for FDD cells Srxlev gt 0 AND Squal gt 0

for TDD cells Srxlev gt 0

for GSM cells Srxlev gt 0

32

Cell Selection Parameters

Parameter Object Range Default Value Recommended Value Class

qQualMin CellSelectionInfo Int [-240]

(dB)

-10 -16 C2

qRxLevMin CellSelectionInfo Int [-115-25]

Step = 2 (dBm)

-45 -115 C2

maxAllowedUlTxPower UlUsPowerConf Int [-5033]

(dBm)

33 33 C3

P_Max = maximum UE output power (dBm) according to its class

Power Class Maximum Output Power (dBm)

1 33

2 27

3 24

4 21

33

Cell Reselection Procedure

Squal

SintraSearch

SinterSearch

SinterRAT Measurement on

same frequency Measurement on

other frequencies Measurement on

other RAT

If Squal = CPICH_EcNo ndash qQualMin lt Threshold

Associated measurements are performed

Thresholds are broadcasted in SIB 11

In UMTS02 2 types of measurements are done Intra frequency and inter RAT

Th

rese

ho

lds

giv

en a

s ex

am

ple

34

Cell Reselection Parameters

Parameter Object Range Default Value Recommended Value Class

qHyst1 CellSelectionInfo Int [040] (dBm)

Step = 2

10 4 C2

qHyst2 CellSelectionInfo

Int [040] (dB)

Step = 2

4 6 C2

qOffset1sn GSMCell

Int [-5050] (dB) 0 TBD C0

qOffset2sn UMTSFDDNeighbouring Int [-5050] (dB) 0 TBD C0

qualMeas CPICH_EcNo or

CPICH_RSCP

CPICH_EcNo NA Static

tReselection CellSelectionInfo Int [031] (s) 31 6 C2

35

Measurements

The different types of air interface measurements are

bull Intra-frequency measurements measurements on downlink physical channels at the same frequency as the active set A measurement object corresponds to one cell

bull Inter-frequency measurements measurements on downlink physical channels at frequencies that differ from the frequency of the active set A measurement object corresponds to one cell

bull Inter-RAT measurements measurements on downlink physical channels belonging to another radio access technology than UTRAN eg GSM A measurement object corresponds to one cell

36

Handover (Handoff) bull There are following categories of handover (also referred to as handoff)

bull Hard handover means that all the old radio links in the UE are removed before

the new radio links are established Hard handover can be seamless or non-seamless Seamless hard handover means that the handover is not perceptible to the user In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover

bull Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN Soft handover is performed by means of macro diversity which refers to the condition that several radio links are active at the same time

bull Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (ie the site of co-located base stations from which several sector-cells are served

37

Handover (Handoff) bull The most obvious cause for performing a handover is that due to its movement a user

can be served in another cell more efficiently (like less power emission less interference) It may however also be performed for other reasons such as system load control

bull Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (ie the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set)

bull The maximum active set size at the RNC is determined by the parameter MaxAciveSetSize

bull 3 to 4 cells the larger the active set size the more likely it is that Iub link efficiency is reduced (more than one resource for a single connection due to SHO)

bull Cells which are not included in the active set but are included in the CELL_INFO_LIST belong to the Monitored Set

bull Cells detected by the UE which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state

38

PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)

bull The primary cell election algorithm applies to soft HO It is used for monitored set determination and a pointer to mobility parameter

bull The Monitored Set should be updated each time the primary cell of active set changes A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set The message contains the cell to addremove from the monitored and should follow the ACIVE SET UPDATE message

bull The primary cell algorithm is called from SHO algorithm therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC

Measurement control used for monitored set update

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

19

Logical Channel Structure

Synchronisation Control Channel (SCCH)

Broadcast Control Channel (BCCH)

Paging Control Channel (PCCH)

Dedicated Control Channel (DCCH)

Dedicated Control Channel (DCCH)Common Control Channel (CCCH)

Control Channel (CCH)

Dedicated Traffic Channel (DTCH)Traffic Channel (TCH)

ODMA Dedicated Control Channel (ODCCH)

ODMA Common Control Channel (OCCCH)

ODMA Dedicated Traffic Channel (ODTCH)

Common Traffic Channel (CTCH)

Shared Channel Control Channel (SHCCH)

(TDD)

(ODMA)

(ODMA)

(TDD)

20

Channels

Transport Channels Dedicated Transport Channel (DCH) ULDL mapped to DCCH and DTCH Broadcast Channel (BCH) DL mapped to BCCH Forward Access Channel (FACH) DL mapped to BCCH CCCH CTCH DCCH and DTCH Paging Channel (PCH) DL mapped to PCCH Random Access Channel (RACH) UL mapped to CCCH DCCH and DTCH Uplink Common Packet Channel (CPCH) UL mapped to DCCH and DTCH Downlink Shared Channel (DSCH) DL mapped to DCCH and DTCH The speech service in UMTS will employ the Adaptive Multi - rate technique 1048707 This is a single integrated codec with eight source rates 122 102 795 740 670 590 515 and 475 kbps To facilitate interoperability with existing cellular networks some of the modes are the same as in existing networks

21

Channels Physical Channels Primary Common Control Physical Channel (PCCPCH) mapped to BCH Secondary Common Control Physical Channel (SCCPCH) mapped to FACH PCH Physical Random Access Channel (PRACH) mapped to RACH Dedicated Physical Data Channel (DPDCH) mapped to DCH Dedicated Physical Control Channel (DPCCH) mapped to DCH Physical Downlink Shared Channel (PDSCH) mapped to DSCH Physical Common Packet Channel (PCPCH) mapped to CPCH Synchronisation Channel (SCH) Common Pilot Channel (CPICH) Acquisition Indicator Channel (AICH) Paging Indication Channel (PICH) CPCH Status Indication Channel (CSICH) Collision DetectionChannel Assignment Indication Channel (CDCA-ICH)

AMR

The bit rate of the AMR speech connection is controlled by the radio access network depending on the air interface loading and the quality of the speech connections During high loading such as during busy hours it is possible to use lower AMR bit rates to offer higher capacity while providing slightly lower speech quality Also if the mobile is running out of the cell coverage area and using its maximum transmission power a lower AMR bit rate can be used to extend the cell coverage area Adaptive multi-rate also contains error concealment The purpose of frame substitution is to conceal the effect of lost speech frames If several frames are lost muting is used to prevent possibly annoying sounds as a result of the frame substitution In P5 with AMR NB it is possible to use lower speech codec rates than 122 kbps The radio network also supports 795 kbps 59 kbps and 475 kbps AMR codecs There is no adaptation in the sense that AMR codecs are changed during an ongoing speech connection rather there is a possibility to adapt the rate at initial selection

23

Link Budget

bull Cell range amp cell capacity are limited by the same parameters

Interference in uplink

Power in downlink

bull Cell breathing phenomenon

ldquoPowerrdquo Link Budget

Tx power + All Gains ndash Path Loss ndash Other losses = Rx power

Path loss = Tx Signal + All Gains ndash Other losses ndash Rx power

Max Path loss = Tx Signal + All Gains ndash Other losses ndash Rx sensitivity

25

Initial Cell Search

The initial Cell Search is carried out in three steps

Step 1 Slot synchronisation - using the primary synchronisation channel

Step 2 Frame synchronisation and code-group identification- using the secondary synchronisation channel

Step 3 Scrambling-code identification-identified through symbol- by-symbol correlation over the primary CCPCH with all the scrambling codes within the code group

26

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

27

Frame Synchronization

helliphellip

2560 chips

acp

Slot

P-SCH acp

Slot

16 11 S-SCH

acp

Slot

2 Group 4 Slot 121314

slot number Scrambling Code Group 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Group 0 1 1 2 8 9 10 15 8 10 16 2 7 15 7 16

Group 1 1 1 5 16 7 3 14 16 3 10 5 12 14 12 10

Group 2 1 2 1 15 5 5 12 16 6 11 2 16 11 15 12

Group 3 1 2 3 1 8 6 5 2 5 8 4 4 6 3 7

Group 4 1 2 16 6 6 11 15 5 12 1 15 12 16 11 2

hellip

Group 61 9 10 13 10 11 15 15 9 16 12 14 13 16 14 11

Group 62 9 11 12 15 12 9 13 13 11 14 10 16 15 14 16

Group 63 9 12 10 15 13 14 9 14 15 11 11 13 12 16 10

256 chips

S-SCH

P-SCH

512 Primary Scrambling Codes divided into 64 groups

28

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

29

Cell Information

P-SCH Coverage indication Slot Synchronization

S-SCH Frame Synchronization Group identification

P-CPICH Scrambling Code Identification

P-CCPCH System Information Broadcast

Logical Channel

BCCH

Transport Channel

BCH

Physical Channel

P-CCPCH

OVSF Cch2561

Primary Scrambling Code

Transmitted during 910th slot

Bit Rate 123 kbps RLC Mode transparent

Mac-B transparent

30

Intra-Frequency Cell Reselection sample

Time

Quality

Serving CellServing Cell

Neighboring Cell

Neighboring Cell

Neighboring

cell criterion S

is fulfilled and is

ranked

Neighboring cell

better ranking

than Serving cell

UE perform cell

reselection

Treselections

Qmeans + Qhyst2s

Qmeann - Qoffset2sn

Qqualmin

UE perform

intra-frequency

measurements

Qqualmin +

SIntraSearch

31

Cell selection and reselection Cell Selection criteria

The cell selection criterion S is fulfilled when

where

Squal = Qqualmeas ndash Qqualmin

Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

Pcompensation ＝ max(UE_TXPWR_MAX_RACH ndash P_MAX 0)

for FDD cells Srxlev gt 0 AND Squal gt 0

for TDD cells Srxlev gt 0

for GSM cells Srxlev gt 0

32

Cell Selection Parameters

Parameter Object Range Default Value Recommended Value Class

qQualMin CellSelectionInfo Int [-240]

(dB)

-10 -16 C2

qRxLevMin CellSelectionInfo Int [-115-25]

Step = 2 (dBm)

-45 -115 C2

maxAllowedUlTxPower UlUsPowerConf Int [-5033]

(dBm)

33 33 C3

P_Max = maximum UE output power (dBm) according to its class

Power Class Maximum Output Power (dBm)

1 33

2 27

3 24

4 21

33

Cell Reselection Procedure

Squal

SintraSearch

SinterSearch

SinterRAT Measurement on

same frequency Measurement on

other frequencies Measurement on

other RAT

If Squal = CPICH_EcNo ndash qQualMin lt Threshold

Associated measurements are performed

Thresholds are broadcasted in SIB 11

In UMTS02 2 types of measurements are done Intra frequency and inter RAT

Th

rese

ho

lds

giv

en a

s ex

am

ple

34

Cell Reselection Parameters

Parameter Object Range Default Value Recommended Value Class

qHyst1 CellSelectionInfo Int [040] (dBm)

Step = 2

10 4 C2

qHyst2 CellSelectionInfo

Int [040] (dB)

Step = 2

4 6 C2

qOffset1sn GSMCell

Int [-5050] (dB) 0 TBD C0

qOffset2sn UMTSFDDNeighbouring Int [-5050] (dB) 0 TBD C0

qualMeas CPICH_EcNo or

CPICH_RSCP

CPICH_EcNo NA Static

tReselection CellSelectionInfo Int [031] (s) 31 6 C2

35

Measurements

The different types of air interface measurements are

bull Intra-frequency measurements measurements on downlink physical channels at the same frequency as the active set A measurement object corresponds to one cell

bull Inter-frequency measurements measurements on downlink physical channels at frequencies that differ from the frequency of the active set A measurement object corresponds to one cell

bull Inter-RAT measurements measurements on downlink physical channels belonging to another radio access technology than UTRAN eg GSM A measurement object corresponds to one cell

36

Handover (Handoff) bull There are following categories of handover (also referred to as handoff)

bull Hard handover means that all the old radio links in the UE are removed before

the new radio links are established Hard handover can be seamless or non-seamless Seamless hard handover means that the handover is not perceptible to the user In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover

bull Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN Soft handover is performed by means of macro diversity which refers to the condition that several radio links are active at the same time

bull Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (ie the site of co-located base stations from which several sector-cells are served

37

Handover (Handoff) bull The most obvious cause for performing a handover is that due to its movement a user

can be served in another cell more efficiently (like less power emission less interference) It may however also be performed for other reasons such as system load control

bull Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (ie the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set)

bull The maximum active set size at the RNC is determined by the parameter MaxAciveSetSize

bull 3 to 4 cells the larger the active set size the more likely it is that Iub link efficiency is reduced (more than one resource for a single connection due to SHO)

bull Cells which are not included in the active set but are included in the CELL_INFO_LIST belong to the Monitored Set

bull Cells detected by the UE which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state

38

PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)

bull The primary cell election algorithm applies to soft HO It is used for monitored set determination and a pointer to mobility parameter

bull The Monitored Set should be updated each time the primary cell of active set changes A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set The message contains the cell to addremove from the monitored and should follow the ACIVE SET UPDATE message

bull The primary cell algorithm is called from SHO algorithm therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC

Measurement control used for monitored set update

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

20

Channels

Transport Channels Dedicated Transport Channel (DCH) ULDL mapped to DCCH and DTCH Broadcast Channel (BCH) DL mapped to BCCH Forward Access Channel (FACH) DL mapped to BCCH CCCH CTCH DCCH and DTCH Paging Channel (PCH) DL mapped to PCCH Random Access Channel (RACH) UL mapped to CCCH DCCH and DTCH Uplink Common Packet Channel (CPCH) UL mapped to DCCH and DTCH Downlink Shared Channel (DSCH) DL mapped to DCCH and DTCH The speech service in UMTS will employ the Adaptive Multi - rate technique 1048707 This is a single integrated codec with eight source rates 122 102 795 740 670 590 515 and 475 kbps To facilitate interoperability with existing cellular networks some of the modes are the same as in existing networks

21

Channels Physical Channels Primary Common Control Physical Channel (PCCPCH) mapped to BCH Secondary Common Control Physical Channel (SCCPCH) mapped to FACH PCH Physical Random Access Channel (PRACH) mapped to RACH Dedicated Physical Data Channel (DPDCH) mapped to DCH Dedicated Physical Control Channel (DPCCH) mapped to DCH Physical Downlink Shared Channel (PDSCH) mapped to DSCH Physical Common Packet Channel (PCPCH) mapped to CPCH Synchronisation Channel (SCH) Common Pilot Channel (CPICH) Acquisition Indicator Channel (AICH) Paging Indication Channel (PICH) CPCH Status Indication Channel (CSICH) Collision DetectionChannel Assignment Indication Channel (CDCA-ICH)

AMR

The bit rate of the AMR speech connection is controlled by the radio access network depending on the air interface loading and the quality of the speech connections During high loading such as during busy hours it is possible to use lower AMR bit rates to offer higher capacity while providing slightly lower speech quality Also if the mobile is running out of the cell coverage area and using its maximum transmission power a lower AMR bit rate can be used to extend the cell coverage area Adaptive multi-rate also contains error concealment The purpose of frame substitution is to conceal the effect of lost speech frames If several frames are lost muting is used to prevent possibly annoying sounds as a result of the frame substitution In P5 with AMR NB it is possible to use lower speech codec rates than 122 kbps The radio network also supports 795 kbps 59 kbps and 475 kbps AMR codecs There is no adaptation in the sense that AMR codecs are changed during an ongoing speech connection rather there is a possibility to adapt the rate at initial selection

23

Link Budget

bull Cell range amp cell capacity are limited by the same parameters

Interference in uplink

Power in downlink

bull Cell breathing phenomenon

ldquoPowerrdquo Link Budget

Tx power + All Gains ndash Path Loss ndash Other losses = Rx power

Path loss = Tx Signal + All Gains ndash Other losses ndash Rx power

Max Path loss = Tx Signal + All Gains ndash Other losses ndash Rx sensitivity

25

Initial Cell Search

The initial Cell Search is carried out in three steps

Step 1 Slot synchronisation - using the primary synchronisation channel

Step 2 Frame synchronisation and code-group identification- using the secondary synchronisation channel

Step 3 Scrambling-code identification-identified through symbol- by-symbol correlation over the primary CCPCH with all the scrambling codes within the code group

26

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

27

Frame Synchronization

helliphellip

2560 chips

acp

Slot

P-SCH acp

Slot

16 11 S-SCH

acp

Slot

2 Group 4 Slot 121314

slot number Scrambling Code Group 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Group 0 1 1 2 8 9 10 15 8 10 16 2 7 15 7 16

Group 1 1 1 5 16 7 3 14 16 3 10 5 12 14 12 10

Group 2 1 2 1 15 5 5 12 16 6 11 2 16 11 15 12

Group 3 1 2 3 1 8 6 5 2 5 8 4 4 6 3 7

Group 4 1 2 16 6 6 11 15 5 12 1 15 12 16 11 2

hellip

Group 61 9 10 13 10 11 15 15 9 16 12 14 13 16 14 11

Group 62 9 11 12 15 12 9 13 13 11 14 10 16 15 14 16

Group 63 9 12 10 15 13 14 9 14 15 11 11 13 12 16 10

256 chips

S-SCH

P-SCH

512 Primary Scrambling Codes divided into 64 groups

28

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

29

Cell Information

P-SCH Coverage indication Slot Synchronization

S-SCH Frame Synchronization Group identification

P-CPICH Scrambling Code Identification

P-CCPCH System Information Broadcast

Logical Channel

BCCH

Transport Channel

BCH

Physical Channel

P-CCPCH

OVSF Cch2561

Primary Scrambling Code

Transmitted during 910th slot

Bit Rate 123 kbps RLC Mode transparent

Mac-B transparent

30

Intra-Frequency Cell Reselection sample

Time

Quality

Serving CellServing Cell

Neighboring Cell

Neighboring Cell

Neighboring

cell criterion S

is fulfilled and is

ranked

Neighboring cell

better ranking

than Serving cell

UE perform cell

reselection

Treselections

Qmeans + Qhyst2s

Qmeann - Qoffset2sn

Qqualmin

UE perform

intra-frequency

measurements

Qqualmin +

SIntraSearch

31

Cell selection and reselection Cell Selection criteria

The cell selection criterion S is fulfilled when

where

Squal = Qqualmeas ndash Qqualmin

Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

Pcompensation ＝ max(UE_TXPWR_MAX_RACH ndash P_MAX 0)

for FDD cells Srxlev gt 0 AND Squal gt 0

for TDD cells Srxlev gt 0

for GSM cells Srxlev gt 0

32

Cell Selection Parameters

Parameter Object Range Default Value Recommended Value Class

qQualMin CellSelectionInfo Int [-240]

(dB)

-10 -16 C2

qRxLevMin CellSelectionInfo Int [-115-25]

Step = 2 (dBm)

-45 -115 C2

maxAllowedUlTxPower UlUsPowerConf Int [-5033]

(dBm)

33 33 C3

P_Max = maximum UE output power (dBm) according to its class

Power Class Maximum Output Power (dBm)

1 33

2 27

3 24

4 21

33

Cell Reselection Procedure

Squal

SintraSearch

SinterSearch

SinterRAT Measurement on

same frequency Measurement on

other frequencies Measurement on

other RAT

If Squal = CPICH_EcNo ndash qQualMin lt Threshold

Associated measurements are performed

Thresholds are broadcasted in SIB 11

In UMTS02 2 types of measurements are done Intra frequency and inter RAT

Th

rese

ho

lds

giv

en a

s ex

am

ple

34

Cell Reselection Parameters

Parameter Object Range Default Value Recommended Value Class

qHyst1 CellSelectionInfo Int [040] (dBm)

Step = 2

10 4 C2

qHyst2 CellSelectionInfo

Int [040] (dB)

Step = 2

4 6 C2

qOffset1sn GSMCell

Int [-5050] (dB) 0 TBD C0

qOffset2sn UMTSFDDNeighbouring Int [-5050] (dB) 0 TBD C0

qualMeas CPICH_EcNo or

CPICH_RSCP

CPICH_EcNo NA Static

tReselection CellSelectionInfo Int [031] (s) 31 6 C2

35

Measurements

The different types of air interface measurements are

bull Intra-frequency measurements measurements on downlink physical channels at the same frequency as the active set A measurement object corresponds to one cell

bull Inter-frequency measurements measurements on downlink physical channels at frequencies that differ from the frequency of the active set A measurement object corresponds to one cell

bull Inter-RAT measurements measurements on downlink physical channels belonging to another radio access technology than UTRAN eg GSM A measurement object corresponds to one cell

36

Handover (Handoff) bull There are following categories of handover (also referred to as handoff)

bull Hard handover means that all the old radio links in the UE are removed before

the new radio links are established Hard handover can be seamless or non-seamless Seamless hard handover means that the handover is not perceptible to the user In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover

bull Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN Soft handover is performed by means of macro diversity which refers to the condition that several radio links are active at the same time

bull Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (ie the site of co-located base stations from which several sector-cells are served

37

Handover (Handoff) bull The most obvious cause for performing a handover is that due to its movement a user

can be served in another cell more efficiently (like less power emission less interference) It may however also be performed for other reasons such as system load control

bull Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (ie the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set)

bull The maximum active set size at the RNC is determined by the parameter MaxAciveSetSize

bull 3 to 4 cells the larger the active set size the more likely it is that Iub link efficiency is reduced (more than one resource for a single connection due to SHO)

bull Cells which are not included in the active set but are included in the CELL_INFO_LIST belong to the Monitored Set

bull Cells detected by the UE which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state

38

PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)

bull The primary cell election algorithm applies to soft HO It is used for monitored set determination and a pointer to mobility parameter

bull The Monitored Set should be updated each time the primary cell of active set changes A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set The message contains the cell to addremove from the monitored and should follow the ACIVE SET UPDATE message

bull The primary cell algorithm is called from SHO algorithm therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC

Measurement control used for monitored set update

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

21

Channels Physical Channels Primary Common Control Physical Channel (PCCPCH) mapped to BCH Secondary Common Control Physical Channel (SCCPCH) mapped to FACH PCH Physical Random Access Channel (PRACH) mapped to RACH Dedicated Physical Data Channel (DPDCH) mapped to DCH Dedicated Physical Control Channel (DPCCH) mapped to DCH Physical Downlink Shared Channel (PDSCH) mapped to DSCH Physical Common Packet Channel (PCPCH) mapped to CPCH Synchronisation Channel (SCH) Common Pilot Channel (CPICH) Acquisition Indicator Channel (AICH) Paging Indication Channel (PICH) CPCH Status Indication Channel (CSICH) Collision DetectionChannel Assignment Indication Channel (CDCA-ICH)

AMR

The bit rate of the AMR speech connection is controlled by the radio access network depending on the air interface loading and the quality of the speech connections During high loading such as during busy hours it is possible to use lower AMR bit rates to offer higher capacity while providing slightly lower speech quality Also if the mobile is running out of the cell coverage area and using its maximum transmission power a lower AMR bit rate can be used to extend the cell coverage area Adaptive multi-rate also contains error concealment The purpose of frame substitution is to conceal the effect of lost speech frames If several frames are lost muting is used to prevent possibly annoying sounds as a result of the frame substitution In P5 with AMR NB it is possible to use lower speech codec rates than 122 kbps The radio network also supports 795 kbps 59 kbps and 475 kbps AMR codecs There is no adaptation in the sense that AMR codecs are changed during an ongoing speech connection rather there is a possibility to adapt the rate at initial selection

23

Link Budget

bull Cell range amp cell capacity are limited by the same parameters

Interference in uplink

Power in downlink

bull Cell breathing phenomenon

ldquoPowerrdquo Link Budget

Tx power + All Gains ndash Path Loss ndash Other losses = Rx power

Path loss = Tx Signal + All Gains ndash Other losses ndash Rx power

Max Path loss = Tx Signal + All Gains ndash Other losses ndash Rx sensitivity

25

Initial Cell Search

The initial Cell Search is carried out in three steps

Step 1 Slot synchronisation - using the primary synchronisation channel

Step 2 Frame synchronisation and code-group identification- using the secondary synchronisation channel

Step 3 Scrambling-code identification-identified through symbol- by-symbol correlation over the primary CCPCH with all the scrambling codes within the code group

26

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

27

Frame Synchronization

helliphellip

2560 chips

acp

Slot

P-SCH acp

Slot

16 11 S-SCH

acp

Slot

2 Group 4 Slot 121314

slot number Scrambling Code Group 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Group 0 1 1 2 8 9 10 15 8 10 16 2 7 15 7 16

Group 1 1 1 5 16 7 3 14 16 3 10 5 12 14 12 10

Group 2 1 2 1 15 5 5 12 16 6 11 2 16 11 15 12

Group 3 1 2 3 1 8 6 5 2 5 8 4 4 6 3 7

Group 4 1 2 16 6 6 11 15 5 12 1 15 12 16 11 2

hellip

Group 61 9 10 13 10 11 15 15 9 16 12 14 13 16 14 11

Group 62 9 11 12 15 12 9 13 13 11 14 10 16 15 14 16

Group 63 9 12 10 15 13 14 9 14 15 11 11 13 12 16 10

256 chips

S-SCH

P-SCH

512 Primary Scrambling Codes divided into 64 groups

28

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

29

Cell Information

P-SCH Coverage indication Slot Synchronization

S-SCH Frame Synchronization Group identification

P-CPICH Scrambling Code Identification

P-CCPCH System Information Broadcast

Logical Channel

BCCH

Transport Channel

BCH

Physical Channel

P-CCPCH

OVSF Cch2561

Primary Scrambling Code

Transmitted during 910th slot

Bit Rate 123 kbps RLC Mode transparent

Mac-B transparent

30

Intra-Frequency Cell Reselection sample

Time

Quality

Serving CellServing Cell

Neighboring Cell

Neighboring Cell

Neighboring

cell criterion S

is fulfilled and is

ranked

Neighboring cell

better ranking

than Serving cell

UE perform cell

reselection

Treselections

Qmeans + Qhyst2s

Qmeann - Qoffset2sn

Qqualmin

UE perform

intra-frequency

measurements

Qqualmin +

SIntraSearch

31

Cell selection and reselection Cell Selection criteria

The cell selection criterion S is fulfilled when

where

Squal = Qqualmeas ndash Qqualmin

Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

Pcompensation ＝ max(UE_TXPWR_MAX_RACH ndash P_MAX 0)

for FDD cells Srxlev gt 0 AND Squal gt 0

for TDD cells Srxlev gt 0

for GSM cells Srxlev gt 0

32

Cell Selection Parameters

Parameter Object Range Default Value Recommended Value Class

qQualMin CellSelectionInfo Int [-240]

(dB)

-10 -16 C2

qRxLevMin CellSelectionInfo Int [-115-25]

Step = 2 (dBm)

-45 -115 C2

maxAllowedUlTxPower UlUsPowerConf Int [-5033]

(dBm)

33 33 C3

P_Max = maximum UE output power (dBm) according to its class

Power Class Maximum Output Power (dBm)

1 33

2 27

3 24

4 21

33

Cell Reselection Procedure

Squal

SintraSearch

SinterSearch

SinterRAT Measurement on

same frequency Measurement on

other frequencies Measurement on

other RAT

If Squal = CPICH_EcNo ndash qQualMin lt Threshold

Associated measurements are performed

Thresholds are broadcasted in SIB 11

In UMTS02 2 types of measurements are done Intra frequency and inter RAT

Th

rese

ho

lds

giv

en a

s ex

am

ple

34

Cell Reselection Parameters

Parameter Object Range Default Value Recommended Value Class

qHyst1 CellSelectionInfo Int [040] (dBm)

Step = 2

10 4 C2

qHyst2 CellSelectionInfo

Int [040] (dB)

Step = 2

4 6 C2

qOffset1sn GSMCell

Int [-5050] (dB) 0 TBD C0

qOffset2sn UMTSFDDNeighbouring Int [-5050] (dB) 0 TBD C0

qualMeas CPICH_EcNo or

CPICH_RSCP

CPICH_EcNo NA Static

tReselection CellSelectionInfo Int [031] (s) 31 6 C2

35

Measurements

The different types of air interface measurements are

bull Intra-frequency measurements measurements on downlink physical channels at the same frequency as the active set A measurement object corresponds to one cell

bull Inter-frequency measurements measurements on downlink physical channels at frequencies that differ from the frequency of the active set A measurement object corresponds to one cell

bull Inter-RAT measurements measurements on downlink physical channels belonging to another radio access technology than UTRAN eg GSM A measurement object corresponds to one cell

36

Handover (Handoff) bull There are following categories of handover (also referred to as handoff)

bull Hard handover means that all the old radio links in the UE are removed before

the new radio links are established Hard handover can be seamless or non-seamless Seamless hard handover means that the handover is not perceptible to the user In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover

bull Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN Soft handover is performed by means of macro diversity which refers to the condition that several radio links are active at the same time

bull Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (ie the site of co-located base stations from which several sector-cells are served

37

Handover (Handoff) bull The most obvious cause for performing a handover is that due to its movement a user

can be served in another cell more efficiently (like less power emission less interference) It may however also be performed for other reasons such as system load control

bull Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (ie the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set)

bull The maximum active set size at the RNC is determined by the parameter MaxAciveSetSize

bull 3 to 4 cells the larger the active set size the more likely it is that Iub link efficiency is reduced (more than one resource for a single connection due to SHO)

bull Cells which are not included in the active set but are included in the CELL_INFO_LIST belong to the Monitored Set

bull Cells detected by the UE which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state

38

PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)

bull The primary cell election algorithm applies to soft HO It is used for monitored set determination and a pointer to mobility parameter

bull The Monitored Set should be updated each time the primary cell of active set changes A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set The message contains the cell to addremove from the monitored and should follow the ACIVE SET UPDATE message

bull The primary cell algorithm is called from SHO algorithm therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC

Measurement control used for monitored set update

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

AMR

The bit rate of the AMR speech connection is controlled by the radio access network depending on the air interface loading and the quality of the speech connections During high loading such as during busy hours it is possible to use lower AMR bit rates to offer higher capacity while providing slightly lower speech quality Also if the mobile is running out of the cell coverage area and using its maximum transmission power a lower AMR bit rate can be used to extend the cell coverage area Adaptive multi-rate also contains error concealment The purpose of frame substitution is to conceal the effect of lost speech frames If several frames are lost muting is used to prevent possibly annoying sounds as a result of the frame substitution In P5 with AMR NB it is possible to use lower speech codec rates than 122 kbps The radio network also supports 795 kbps 59 kbps and 475 kbps AMR codecs There is no adaptation in the sense that AMR codecs are changed during an ongoing speech connection rather there is a possibility to adapt the rate at initial selection

23

Link Budget

bull Cell range amp cell capacity are limited by the same parameters

Interference in uplink

Power in downlink

bull Cell breathing phenomenon

ldquoPowerrdquo Link Budget

Tx power + All Gains ndash Path Loss ndash Other losses = Rx power

Path loss = Tx Signal + All Gains ndash Other losses ndash Rx power

Max Path loss = Tx Signal + All Gains ndash Other losses ndash Rx sensitivity

25

Initial Cell Search

The initial Cell Search is carried out in three steps

Step 1 Slot synchronisation - using the primary synchronisation channel

Step 2 Frame synchronisation and code-group identification- using the secondary synchronisation channel

Step 3 Scrambling-code identification-identified through symbol- by-symbol correlation over the primary CCPCH with all the scrambling codes within the code group

26

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

27

Frame Synchronization

helliphellip

2560 chips

acp

Slot

P-SCH acp

Slot

16 11 S-SCH

acp

Slot

2 Group 4 Slot 121314

slot number Scrambling Code Group 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Group 0 1 1 2 8 9 10 15 8 10 16 2 7 15 7 16

Group 1 1 1 5 16 7 3 14 16 3 10 5 12 14 12 10

Group 2 1 2 1 15 5 5 12 16 6 11 2 16 11 15 12

Group 3 1 2 3 1 8 6 5 2 5 8 4 4 6 3 7

Group 4 1 2 16 6 6 11 15 5 12 1 15 12 16 11 2

hellip

Group 61 9 10 13 10 11 15 15 9 16 12 14 13 16 14 11

Group 62 9 11 12 15 12 9 13 13 11 14 10 16 15 14 16

Group 63 9 12 10 15 13 14 9 14 15 11 11 13 12 16 10

256 chips

S-SCH

P-SCH

512 Primary Scrambling Codes divided into 64 groups

28

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

29

Cell Information

P-SCH Coverage indication Slot Synchronization

S-SCH Frame Synchronization Group identification

P-CPICH Scrambling Code Identification

P-CCPCH System Information Broadcast

Logical Channel

BCCH

Transport Channel

BCH

Physical Channel

P-CCPCH

OVSF Cch2561

Primary Scrambling Code

Transmitted during 910th slot

Bit Rate 123 kbps RLC Mode transparent

Mac-B transparent

30

Intra-Frequency Cell Reselection sample

Time

Quality

Serving CellServing Cell

Neighboring Cell

Neighboring Cell

Neighboring

cell criterion S

is fulfilled and is

ranked

Neighboring cell

better ranking

than Serving cell

UE perform cell

reselection

Treselections

Qmeans + Qhyst2s

Qmeann - Qoffset2sn

Qqualmin

UE perform

intra-frequency

measurements

Qqualmin +

SIntraSearch

31

Cell selection and reselection Cell Selection criteria

The cell selection criterion S is fulfilled when

where

Squal = Qqualmeas ndash Qqualmin

Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

Pcompensation ＝ max(UE_TXPWR_MAX_RACH ndash P_MAX 0)

for FDD cells Srxlev gt 0 AND Squal gt 0

for TDD cells Srxlev gt 0

for GSM cells Srxlev gt 0

32

Cell Selection Parameters

Parameter Object Range Default Value Recommended Value Class

qQualMin CellSelectionInfo Int [-240]

(dB)

-10 -16 C2

qRxLevMin CellSelectionInfo Int [-115-25]

Step = 2 (dBm)

-45 -115 C2

maxAllowedUlTxPower UlUsPowerConf Int [-5033]

(dBm)

33 33 C3

P_Max = maximum UE output power (dBm) according to its class

Power Class Maximum Output Power (dBm)

1 33

2 27

3 24

4 21

33

Cell Reselection Procedure

Squal

SintraSearch

SinterSearch

SinterRAT Measurement on

same frequency Measurement on

other frequencies Measurement on

other RAT

If Squal = CPICH_EcNo ndash qQualMin lt Threshold

Associated measurements are performed

Thresholds are broadcasted in SIB 11

In UMTS02 2 types of measurements are done Intra frequency and inter RAT

Th

rese

ho

lds

giv

en a

s ex

am

ple

34

Cell Reselection Parameters

Parameter Object Range Default Value Recommended Value Class

qHyst1 CellSelectionInfo Int [040] (dBm)

Step = 2

10 4 C2

qHyst2 CellSelectionInfo

Int [040] (dB)

Step = 2

4 6 C2

qOffset1sn GSMCell

Int [-5050] (dB) 0 TBD C0

qOffset2sn UMTSFDDNeighbouring Int [-5050] (dB) 0 TBD C0

qualMeas CPICH_EcNo or

CPICH_RSCP

CPICH_EcNo NA Static

tReselection CellSelectionInfo Int [031] (s) 31 6 C2

35

Measurements

The different types of air interface measurements are

bull Intra-frequency measurements measurements on downlink physical channels at the same frequency as the active set A measurement object corresponds to one cell

bull Inter-frequency measurements measurements on downlink physical channels at frequencies that differ from the frequency of the active set A measurement object corresponds to one cell

bull Inter-RAT measurements measurements on downlink physical channels belonging to another radio access technology than UTRAN eg GSM A measurement object corresponds to one cell

36

Handover (Handoff) bull There are following categories of handover (also referred to as handoff)

bull Hard handover means that all the old radio links in the UE are removed before

the new radio links are established Hard handover can be seamless or non-seamless Seamless hard handover means that the handover is not perceptible to the user In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover

bull Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN Soft handover is performed by means of macro diversity which refers to the condition that several radio links are active at the same time

bull Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (ie the site of co-located base stations from which several sector-cells are served

37

Handover (Handoff) bull The most obvious cause for performing a handover is that due to its movement a user

can be served in another cell more efficiently (like less power emission less interference) It may however also be performed for other reasons such as system load control

bull Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (ie the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set)

bull The maximum active set size at the RNC is determined by the parameter MaxAciveSetSize

bull 3 to 4 cells the larger the active set size the more likely it is that Iub link efficiency is reduced (more than one resource for a single connection due to SHO)

bull Cells which are not included in the active set but are included in the CELL_INFO_LIST belong to the Monitored Set

bull Cells detected by the UE which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state

38

PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)

bull The primary cell election algorithm applies to soft HO It is used for monitored set determination and a pointer to mobility parameter

bull The Monitored Set should be updated each time the primary cell of active set changes A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set The message contains the cell to addremove from the monitored and should follow the ACIVE SET UPDATE message

bull The primary cell algorithm is called from SHO algorithm therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC

Measurement control used for monitored set update

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

23

Link Budget

bull Cell range amp cell capacity are limited by the same parameters

Interference in uplink

Power in downlink

bull Cell breathing phenomenon

ldquoPowerrdquo Link Budget

Tx power + All Gains ndash Path Loss ndash Other losses = Rx power

Path loss = Tx Signal + All Gains ndash Other losses ndash Rx power

Max Path loss = Tx Signal + All Gains ndash Other losses ndash Rx sensitivity

25

Initial Cell Search

The initial Cell Search is carried out in three steps

Step 1 Slot synchronisation - using the primary synchronisation channel

Step 2 Frame synchronisation and code-group identification- using the secondary synchronisation channel

Step 3 Scrambling-code identification-identified through symbol- by-symbol correlation over the primary CCPCH with all the scrambling codes within the code group

26

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

27

Frame Synchronization

helliphellip

2560 chips

acp

Slot

P-SCH acp

Slot

16 11 S-SCH

acp

Slot

2 Group 4 Slot 121314

slot number Scrambling Code Group 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Group 0 1 1 2 8 9 10 15 8 10 16 2 7 15 7 16

Group 1 1 1 5 16 7 3 14 16 3 10 5 12 14 12 10

Group 2 1 2 1 15 5 5 12 16 6 11 2 16 11 15 12

Group 3 1 2 3 1 8 6 5 2 5 8 4 4 6 3 7

Group 4 1 2 16 6 6 11 15 5 12 1 15 12 16 11 2

hellip

Group 61 9 10 13 10 11 15 15 9 16 12 14 13 16 14 11

Group 62 9 11 12 15 12 9 13 13 11 14 10 16 15 14 16

Group 63 9 12 10 15 13 14 9 14 15 11 11 13 12 16 10

256 chips

S-SCH

P-SCH

512 Primary Scrambling Codes divided into 64 groups

28

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

29

Cell Information

P-SCH Coverage indication Slot Synchronization

S-SCH Frame Synchronization Group identification

P-CPICH Scrambling Code Identification

P-CCPCH System Information Broadcast

Logical Channel

BCCH

Transport Channel

BCH

Physical Channel

P-CCPCH

OVSF Cch2561

Primary Scrambling Code

Transmitted during 910th slot

Bit Rate 123 kbps RLC Mode transparent

Mac-B transparent

30

Intra-Frequency Cell Reselection sample

Time

Quality

Serving CellServing Cell

Neighboring Cell

Neighboring Cell

Neighboring

cell criterion S

is fulfilled and is

ranked

Neighboring cell

better ranking

than Serving cell

UE perform cell

reselection

Treselections

Qmeans + Qhyst2s

Qmeann - Qoffset2sn

Qqualmin

UE perform

intra-frequency

measurements

Qqualmin +

SIntraSearch

31

Cell selection and reselection Cell Selection criteria

The cell selection criterion S is fulfilled when

where

Squal = Qqualmeas ndash Qqualmin

Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

Pcompensation ＝ max(UE_TXPWR_MAX_RACH ndash P_MAX 0)

for FDD cells Srxlev gt 0 AND Squal gt 0

for TDD cells Srxlev gt 0

for GSM cells Srxlev gt 0

32

Cell Selection Parameters

Parameter Object Range Default Value Recommended Value Class

qQualMin CellSelectionInfo Int [-240]

(dB)

-10 -16 C2

qRxLevMin CellSelectionInfo Int [-115-25]

Step = 2 (dBm)

-45 -115 C2

maxAllowedUlTxPower UlUsPowerConf Int [-5033]

(dBm)

33 33 C3

P_Max = maximum UE output power (dBm) according to its class

Power Class Maximum Output Power (dBm)

1 33

2 27

3 24

4 21

33

Cell Reselection Procedure

Squal

SintraSearch

SinterSearch

SinterRAT Measurement on

same frequency Measurement on

other frequencies Measurement on

other RAT

If Squal = CPICH_EcNo ndash qQualMin lt Threshold

Associated measurements are performed

Thresholds are broadcasted in SIB 11

In UMTS02 2 types of measurements are done Intra frequency and inter RAT

Th

rese

ho

lds

giv

en a

s ex

am

ple

34

Cell Reselection Parameters

Parameter Object Range Default Value Recommended Value Class

qHyst1 CellSelectionInfo Int [040] (dBm)

Step = 2

10 4 C2

qHyst2 CellSelectionInfo

Int [040] (dB)

Step = 2

4 6 C2

qOffset1sn GSMCell

Int [-5050] (dB) 0 TBD C0

qOffset2sn UMTSFDDNeighbouring Int [-5050] (dB) 0 TBD C0

qualMeas CPICH_EcNo or

CPICH_RSCP

CPICH_EcNo NA Static

tReselection CellSelectionInfo Int [031] (s) 31 6 C2

35

Measurements

The different types of air interface measurements are

bull Intra-frequency measurements measurements on downlink physical channels at the same frequency as the active set A measurement object corresponds to one cell

bull Inter-frequency measurements measurements on downlink physical channels at frequencies that differ from the frequency of the active set A measurement object corresponds to one cell

bull Inter-RAT measurements measurements on downlink physical channels belonging to another radio access technology than UTRAN eg GSM A measurement object corresponds to one cell

36

Handover (Handoff) bull There are following categories of handover (also referred to as handoff)

bull Hard handover means that all the old radio links in the UE are removed before

the new radio links are established Hard handover can be seamless or non-seamless Seamless hard handover means that the handover is not perceptible to the user In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover

bull Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN Soft handover is performed by means of macro diversity which refers to the condition that several radio links are active at the same time

bull Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (ie the site of co-located base stations from which several sector-cells are served

37

Handover (Handoff) bull The most obvious cause for performing a handover is that due to its movement a user

can be served in another cell more efficiently (like less power emission less interference) It may however also be performed for other reasons such as system load control

bull Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (ie the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set)

bull The maximum active set size at the RNC is determined by the parameter MaxAciveSetSize

bull 3 to 4 cells the larger the active set size the more likely it is that Iub link efficiency is reduced (more than one resource for a single connection due to SHO)

bull Cells which are not included in the active set but are included in the CELL_INFO_LIST belong to the Monitored Set

bull Cells detected by the UE which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state

38

PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)

bull The primary cell election algorithm applies to soft HO It is used for monitored set determination and a pointer to mobility parameter

bull The Monitored Set should be updated each time the primary cell of active set changes A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set The message contains the cell to addremove from the monitored and should follow the ACIVE SET UPDATE message

bull The primary cell algorithm is called from SHO algorithm therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC

Measurement control used for monitored set update

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

ldquoPowerrdquo Link Budget

Tx power + All Gains ndash Path Loss ndash Other losses = Rx power

Path loss = Tx Signal + All Gains ndash Other losses ndash Rx power

Max Path loss = Tx Signal + All Gains ndash Other losses ndash Rx sensitivity

25

Initial Cell Search

The initial Cell Search is carried out in three steps

Step 1 Slot synchronisation - using the primary synchronisation channel

Step 2 Frame synchronisation and code-group identification- using the secondary synchronisation channel

Step 3 Scrambling-code identification-identified through symbol- by-symbol correlation over the primary CCPCH with all the scrambling codes within the code group

26

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

27

Frame Synchronization

helliphellip

2560 chips

acp

Slot

P-SCH acp

Slot

16 11 S-SCH

acp

Slot

2 Group 4 Slot 121314

slot number Scrambling Code Group 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Group 0 1 1 2 8 9 10 15 8 10 16 2 7 15 7 16

Group 1 1 1 5 16 7 3 14 16 3 10 5 12 14 12 10

Group 2 1 2 1 15 5 5 12 16 6 11 2 16 11 15 12

Group 3 1 2 3 1 8 6 5 2 5 8 4 4 6 3 7

Group 4 1 2 16 6 6 11 15 5 12 1 15 12 16 11 2

hellip

Group 61 9 10 13 10 11 15 15 9 16 12 14 13 16 14 11

Group 62 9 11 12 15 12 9 13 13 11 14 10 16 15 14 16

Group 63 9 12 10 15 13 14 9 14 15 11 11 13 12 16 10

256 chips

S-SCH

P-SCH

512 Primary Scrambling Codes divided into 64 groups

28

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

29

Cell Information

P-SCH Coverage indication Slot Synchronization

S-SCH Frame Synchronization Group identification

P-CPICH Scrambling Code Identification

P-CCPCH System Information Broadcast

Logical Channel

BCCH

Transport Channel

BCH

Physical Channel

P-CCPCH

OVSF Cch2561

Primary Scrambling Code

Transmitted during 910th slot

Bit Rate 123 kbps RLC Mode transparent

Mac-B transparent

30

Intra-Frequency Cell Reselection sample

Time

Quality

Serving CellServing Cell

Neighboring Cell

Neighboring Cell

Neighboring

cell criterion S

is fulfilled and is

ranked

Neighboring cell

better ranking

than Serving cell

UE perform cell

reselection

Treselections

Qmeans + Qhyst2s

Qmeann - Qoffset2sn

Qqualmin

UE perform

intra-frequency

measurements

Qqualmin +

SIntraSearch

31

Cell selection and reselection Cell Selection criteria

The cell selection criterion S is fulfilled when

where

Squal = Qqualmeas ndash Qqualmin

Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

Pcompensation ＝ max(UE_TXPWR_MAX_RACH ndash P_MAX 0)

for FDD cells Srxlev gt 0 AND Squal gt 0

for TDD cells Srxlev gt 0

for GSM cells Srxlev gt 0

32

Cell Selection Parameters

Parameter Object Range Default Value Recommended Value Class

qQualMin CellSelectionInfo Int [-240]

(dB)

-10 -16 C2

qRxLevMin CellSelectionInfo Int [-115-25]

Step = 2 (dBm)

-45 -115 C2

maxAllowedUlTxPower UlUsPowerConf Int [-5033]

(dBm)

33 33 C3

P_Max = maximum UE output power (dBm) according to its class

Power Class Maximum Output Power (dBm)

1 33

2 27

3 24

4 21

33

Cell Reselection Procedure

Squal

SintraSearch

SinterSearch

SinterRAT Measurement on

same frequency Measurement on

other frequencies Measurement on

other RAT

If Squal = CPICH_EcNo ndash qQualMin lt Threshold

Associated measurements are performed

Thresholds are broadcasted in SIB 11

In UMTS02 2 types of measurements are done Intra frequency and inter RAT

Th

rese

ho

lds

giv

en a

s ex

am

ple

34

Cell Reselection Parameters

Parameter Object Range Default Value Recommended Value Class

qHyst1 CellSelectionInfo Int [040] (dBm)

Step = 2

10 4 C2

qHyst2 CellSelectionInfo

Int [040] (dB)

Step = 2

4 6 C2

qOffset1sn GSMCell

Int [-5050] (dB) 0 TBD C0

qOffset2sn UMTSFDDNeighbouring Int [-5050] (dB) 0 TBD C0

qualMeas CPICH_EcNo or

CPICH_RSCP

CPICH_EcNo NA Static

tReselection CellSelectionInfo Int [031] (s) 31 6 C2

35

Measurements

The different types of air interface measurements are

bull Intra-frequency measurements measurements on downlink physical channels at the same frequency as the active set A measurement object corresponds to one cell

bull Inter-frequency measurements measurements on downlink physical channels at frequencies that differ from the frequency of the active set A measurement object corresponds to one cell

bull Inter-RAT measurements measurements on downlink physical channels belonging to another radio access technology than UTRAN eg GSM A measurement object corresponds to one cell

36

Handover (Handoff) bull There are following categories of handover (also referred to as handoff)

bull Hard handover means that all the old radio links in the UE are removed before

the new radio links are established Hard handover can be seamless or non-seamless Seamless hard handover means that the handover is not perceptible to the user In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover

bull Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN Soft handover is performed by means of macro diversity which refers to the condition that several radio links are active at the same time

bull Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (ie the site of co-located base stations from which several sector-cells are served

37

Handover (Handoff) bull The most obvious cause for performing a handover is that due to its movement a user

can be served in another cell more efficiently (like less power emission less interference) It may however also be performed for other reasons such as system load control

bull Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (ie the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set)

bull The maximum active set size at the RNC is determined by the parameter MaxAciveSetSize

bull 3 to 4 cells the larger the active set size the more likely it is that Iub link efficiency is reduced (more than one resource for a single connection due to SHO)

bull Cells which are not included in the active set but are included in the CELL_INFO_LIST belong to the Monitored Set

bull Cells detected by the UE which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state

38

PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)

bull The primary cell election algorithm applies to soft HO It is used for monitored set determination and a pointer to mobility parameter

bull The Monitored Set should be updated each time the primary cell of active set changes A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set The message contains the cell to addremove from the monitored and should follow the ACIVE SET UPDATE message

bull The primary cell algorithm is called from SHO algorithm therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC

Measurement control used for monitored set update

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

25

Initial Cell Search

The initial Cell Search is carried out in three steps

Step 1 Slot synchronisation - using the primary synchronisation channel

Step 2 Frame synchronisation and code-group identification- using the secondary synchronisation channel

Step 3 Scrambling-code identification-identified through symbol- by-symbol correlation over the primary CCPCH with all the scrambling codes within the code group

26

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

27

Frame Synchronization

helliphellip

2560 chips

acp

Slot

P-SCH acp

Slot

16 11 S-SCH

acp

Slot

2 Group 4 Slot 121314

slot number Scrambling Code Group 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Group 0 1 1 2 8 9 10 15 8 10 16 2 7 15 7 16

Group 1 1 1 5 16 7 3 14 16 3 10 5 12 14 12 10

Group 2 1 2 1 15 5 5 12 16 6 11 2 16 11 15 12

Group 3 1 2 3 1 8 6 5 2 5 8 4 4 6 3 7

Group 4 1 2 16 6 6 11 15 5 12 1 15 12 16 11 2

hellip

Group 61 9 10 13 10 11 15 15 9 16 12 14 13 16 14 11

Group 62 9 11 12 15 12 9 13 13 11 14 10 16 15 14 16

Group 63 9 12 10 15 13 14 9 14 15 11 11 13 12 16 10

256 chips

S-SCH

P-SCH

512 Primary Scrambling Codes divided into 64 groups

28

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

29

Cell Information

P-SCH Coverage indication Slot Synchronization

S-SCH Frame Synchronization Group identification

P-CPICH Scrambling Code Identification

P-CCPCH System Information Broadcast

Logical Channel

BCCH

Transport Channel

BCH

Physical Channel

P-CCPCH

OVSF Cch2561

Primary Scrambling Code

Transmitted during 910th slot

Bit Rate 123 kbps RLC Mode transparent

Mac-B transparent

30

Intra-Frequency Cell Reselection sample

Time

Quality

Serving CellServing Cell

Neighboring Cell

Neighboring Cell

Neighboring

cell criterion S

is fulfilled and is

ranked

Neighboring cell

better ranking

than Serving cell

UE perform cell

reselection

Treselections

Qmeans + Qhyst2s

Qmeann - Qoffset2sn

Qqualmin

UE perform

intra-frequency

measurements

Qqualmin +

SIntraSearch

31

Cell selection and reselection Cell Selection criteria

The cell selection criterion S is fulfilled when

where

Squal = Qqualmeas ndash Qqualmin

Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

Pcompensation ＝ max(UE_TXPWR_MAX_RACH ndash P_MAX 0)

for FDD cells Srxlev gt 0 AND Squal gt 0

for TDD cells Srxlev gt 0

for GSM cells Srxlev gt 0

32

Cell Selection Parameters

Parameter Object Range Default Value Recommended Value Class

qQualMin CellSelectionInfo Int [-240]

(dB)

-10 -16 C2

qRxLevMin CellSelectionInfo Int [-115-25]

Step = 2 (dBm)

-45 -115 C2

maxAllowedUlTxPower UlUsPowerConf Int [-5033]

(dBm)

33 33 C3

P_Max = maximum UE output power (dBm) according to its class

Power Class Maximum Output Power (dBm)

1 33

2 27

3 24

4 21

33

Cell Reselection Procedure

Squal

SintraSearch

SinterSearch

SinterRAT Measurement on

same frequency Measurement on

other frequencies Measurement on

other RAT

If Squal = CPICH_EcNo ndash qQualMin lt Threshold

Associated measurements are performed

Thresholds are broadcasted in SIB 11

In UMTS02 2 types of measurements are done Intra frequency and inter RAT

Th

rese

ho

lds

giv

en a

s ex

am

ple

34

Cell Reselection Parameters

Parameter Object Range Default Value Recommended Value Class

qHyst1 CellSelectionInfo Int [040] (dBm)

Step = 2

10 4 C2

qHyst2 CellSelectionInfo

Int [040] (dB)

Step = 2

4 6 C2

qOffset1sn GSMCell

Int [-5050] (dB) 0 TBD C0

qOffset2sn UMTSFDDNeighbouring Int [-5050] (dB) 0 TBD C0

qualMeas CPICH_EcNo or

CPICH_RSCP

CPICH_EcNo NA Static

tReselection CellSelectionInfo Int [031] (s) 31 6 C2

35

Measurements

The different types of air interface measurements are

bull Intra-frequency measurements measurements on downlink physical channels at the same frequency as the active set A measurement object corresponds to one cell

bull Inter-frequency measurements measurements on downlink physical channels at frequencies that differ from the frequency of the active set A measurement object corresponds to one cell

bull Inter-RAT measurements measurements on downlink physical channels belonging to another radio access technology than UTRAN eg GSM A measurement object corresponds to one cell

36

Handover (Handoff) bull There are following categories of handover (also referred to as handoff)

bull Hard handover means that all the old radio links in the UE are removed before

the new radio links are established Hard handover can be seamless or non-seamless Seamless hard handover means that the handover is not perceptible to the user In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover

bull Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN Soft handover is performed by means of macro diversity which refers to the condition that several radio links are active at the same time

bull Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (ie the site of co-located base stations from which several sector-cells are served

37

Handover (Handoff) bull The most obvious cause for performing a handover is that due to its movement a user

can be served in another cell more efficiently (like less power emission less interference) It may however also be performed for other reasons such as system load control

bull Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (ie the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set)

bull The maximum active set size at the RNC is determined by the parameter MaxAciveSetSize

bull 3 to 4 cells the larger the active set size the more likely it is that Iub link efficiency is reduced (more than one resource for a single connection due to SHO)

bull Cells which are not included in the active set but are included in the CELL_INFO_LIST belong to the Monitored Set

bull Cells detected by the UE which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state

38

PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)

bull The primary cell election algorithm applies to soft HO It is used for monitored set determination and a pointer to mobility parameter

bull The Monitored Set should be updated each time the primary cell of active set changes A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set The message contains the cell to addremove from the monitored and should follow the ACIVE SET UPDATE message

bull The primary cell algorithm is called from SHO algorithm therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC

Measurement control used for monitored set update

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

26

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

27

Frame Synchronization

helliphellip

2560 chips

acp

Slot

P-SCH acp

Slot

16 11 S-SCH

acp

Slot

2 Group 4 Slot 121314

slot number Scrambling Code Group 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Group 0 1 1 2 8 9 10 15 8 10 16 2 7 15 7 16

Group 1 1 1 5 16 7 3 14 16 3 10 5 12 14 12 10

Group 2 1 2 1 15 5 5 12 16 6 11 2 16 11 15 12

Group 3 1 2 3 1 8 6 5 2 5 8 4 4 6 3 7

Group 4 1 2 16 6 6 11 15 5 12 1 15 12 16 11 2

hellip

Group 61 9 10 13 10 11 15 15 9 16 12 14 13 16 14 11

Group 62 9 11 12 15 12 9 13 13 11 14 10 16 15 14 16

Group 63 9 12 10 15 13 14 9 14 15 11 11 13 12 16 10

256 chips

S-SCH

P-SCH

512 Primary Scrambling Codes divided into 64 groups

28

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

29

Cell Information

P-SCH Coverage indication Slot Synchronization

S-SCH Frame Synchronization Group identification

P-CPICH Scrambling Code Identification

P-CCPCH System Information Broadcast

Logical Channel

BCCH

Transport Channel

BCH

Physical Channel

P-CCPCH

OVSF Cch2561

Primary Scrambling Code

Transmitted during 910th slot

Bit Rate 123 kbps RLC Mode transparent

Mac-B transparent

30

Intra-Frequency Cell Reselection sample

Time

Quality

Serving CellServing Cell

Neighboring Cell

Neighboring Cell

Neighboring

cell criterion S

is fulfilled and is

ranked

Neighboring cell

better ranking

than Serving cell

UE perform cell

reselection

Treselections

Qmeans + Qhyst2s

Qmeann - Qoffset2sn

Qqualmin

UE perform

intra-frequency

measurements

Qqualmin +

SIntraSearch

31

Cell selection and reselection Cell Selection criteria

The cell selection criterion S is fulfilled when

where

Squal = Qqualmeas ndash Qqualmin

Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

Pcompensation ＝ max(UE_TXPWR_MAX_RACH ndash P_MAX 0)

for FDD cells Srxlev gt 0 AND Squal gt 0

for TDD cells Srxlev gt 0

for GSM cells Srxlev gt 0

32

Cell Selection Parameters

Parameter Object Range Default Value Recommended Value Class

qQualMin CellSelectionInfo Int [-240]

(dB)

-10 -16 C2

qRxLevMin CellSelectionInfo Int [-115-25]

Step = 2 (dBm)

-45 -115 C2

maxAllowedUlTxPower UlUsPowerConf Int [-5033]

(dBm)

33 33 C3

P_Max = maximum UE output power (dBm) according to its class

Power Class Maximum Output Power (dBm)

1 33

2 27

3 24

4 21

33

Cell Reselection Procedure

Squal

SintraSearch

SinterSearch

SinterRAT Measurement on

same frequency Measurement on

other frequencies Measurement on

other RAT

If Squal = CPICH_EcNo ndash qQualMin lt Threshold

Associated measurements are performed

Thresholds are broadcasted in SIB 11

In UMTS02 2 types of measurements are done Intra frequency and inter RAT

Th

rese

ho

lds

giv

en a

s ex

am

ple

34

Cell Reselection Parameters

Parameter Object Range Default Value Recommended Value Class

qHyst1 CellSelectionInfo Int [040] (dBm)

Step = 2

10 4 C2

qHyst2 CellSelectionInfo

Int [040] (dB)

Step = 2

4 6 C2

qOffset1sn GSMCell

Int [-5050] (dB) 0 TBD C0

qOffset2sn UMTSFDDNeighbouring Int [-5050] (dB) 0 TBD C0

qualMeas CPICH_EcNo or

CPICH_RSCP

CPICH_EcNo NA Static

tReselection CellSelectionInfo Int [031] (s) 31 6 C2

35

Measurements

The different types of air interface measurements are

bull Intra-frequency measurements measurements on downlink physical channels at the same frequency as the active set A measurement object corresponds to one cell

bull Inter-frequency measurements measurements on downlink physical channels at frequencies that differ from the frequency of the active set A measurement object corresponds to one cell

bull Inter-RAT measurements measurements on downlink physical channels belonging to another radio access technology than UTRAN eg GSM A measurement object corresponds to one cell

36

Handover (Handoff) bull There are following categories of handover (also referred to as handoff)

bull Hard handover means that all the old radio links in the UE are removed before

the new radio links are established Hard handover can be seamless or non-seamless Seamless hard handover means that the handover is not perceptible to the user In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover

bull Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN Soft handover is performed by means of macro diversity which refers to the condition that several radio links are active at the same time

bull Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (ie the site of co-located base stations from which several sector-cells are served

37

Handover (Handoff) bull The most obvious cause for performing a handover is that due to its movement a user

can be served in another cell more efficiently (like less power emission less interference) It may however also be performed for other reasons such as system load control

bull Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (ie the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set)

bull The maximum active set size at the RNC is determined by the parameter MaxAciveSetSize

bull 3 to 4 cells the larger the active set size the more likely it is that Iub link efficiency is reduced (more than one resource for a single connection due to SHO)

bull Cells which are not included in the active set but are included in the CELL_INFO_LIST belong to the Monitored Set

bull Cells detected by the UE which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state

38

PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)

bull The primary cell election algorithm applies to soft HO It is used for monitored set determination and a pointer to mobility parameter

bull The Monitored Set should be updated each time the primary cell of active set changes A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set The message contains the cell to addremove from the monitored and should follow the ACIVE SET UPDATE message

bull The primary cell algorithm is called from SHO algorithm therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC

Measurement control used for monitored set update

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

27

Frame Synchronization

helliphellip

2560 chips

acp

Slot

P-SCH acp

Slot

16 11 S-SCH

acp

Slot

2 Group 4 Slot 121314

slot number Scrambling Code Group 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Group 0 1 1 2 8 9 10 15 8 10 16 2 7 15 7 16

Group 1 1 1 5 16 7 3 14 16 3 10 5 12 14 12 10

Group 2 1 2 1 15 5 5 12 16 6 11 2 16 11 15 12

Group 3 1 2 3 1 8 6 5 2 5 8 4 4 6 3 7

Group 4 1 2 16 6 6 11 15 5 12 1 15 12 16 11 2

hellip

Group 61 9 10 13 10 11 15 15 9 16 12 14 13 16 14 11

Group 62 9 11 12 15 12 9 13 13 11 14 10 16 15 14 16

Group 63 9 12 10 15 13 14 9 14 15 11 11 13 12 16 10

256 chips

S-SCH

P-SCH

512 Primary Scrambling Codes divided into 64 groups

28

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

29

Cell Information

P-SCH Coverage indication Slot Synchronization

S-SCH Frame Synchronization Group identification

P-CPICH Scrambling Code Identification

P-CCPCH System Information Broadcast

Logical Channel

BCCH

Transport Channel

BCH

Physical Channel

P-CCPCH

OVSF Cch2561

Primary Scrambling Code

Transmitted during 910th slot

Bit Rate 123 kbps RLC Mode transparent

Mac-B transparent

30

Intra-Frequency Cell Reselection sample

Time

Quality

Serving CellServing Cell

Neighboring Cell

Neighboring Cell

Neighboring

cell criterion S

is fulfilled and is

ranked

Neighboring cell

better ranking

than Serving cell

UE perform cell

reselection

Treselections

Qmeans + Qhyst2s

Qmeann - Qoffset2sn

Qqualmin

UE perform

intra-frequency

measurements

Qqualmin +

SIntraSearch

31

Cell selection and reselection Cell Selection criteria

The cell selection criterion S is fulfilled when

where

Squal = Qqualmeas ndash Qqualmin

Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

Pcompensation ＝ max(UE_TXPWR_MAX_RACH ndash P_MAX 0)

for FDD cells Srxlev gt 0 AND Squal gt 0

for TDD cells Srxlev gt 0

for GSM cells Srxlev gt 0

32

Cell Selection Parameters

Parameter Object Range Default Value Recommended Value Class

qQualMin CellSelectionInfo Int [-240]

(dB)

-10 -16 C2

qRxLevMin CellSelectionInfo Int [-115-25]

Step = 2 (dBm)

-45 -115 C2

maxAllowedUlTxPower UlUsPowerConf Int [-5033]

(dBm)

33 33 C3

P_Max = maximum UE output power (dBm) according to its class

Power Class Maximum Output Power (dBm)

1 33

2 27

3 24

4 21

33

Cell Reselection Procedure

Squal

SintraSearch

SinterSearch

SinterRAT Measurement on

same frequency Measurement on

other frequencies Measurement on

other RAT

If Squal = CPICH_EcNo ndash qQualMin lt Threshold

Associated measurements are performed

Thresholds are broadcasted in SIB 11

In UMTS02 2 types of measurements are done Intra frequency and inter RAT

Th

rese

ho

lds

giv

en a

s ex

am

ple

34

Cell Reselection Parameters

Parameter Object Range Default Value Recommended Value Class

qHyst1 CellSelectionInfo Int [040] (dBm)

Step = 2

10 4 C2

qHyst2 CellSelectionInfo

Int [040] (dB)

Step = 2

4 6 C2

qOffset1sn GSMCell

Int [-5050] (dB) 0 TBD C0

qOffset2sn UMTSFDDNeighbouring Int [-5050] (dB) 0 TBD C0

qualMeas CPICH_EcNo or

CPICH_RSCP

CPICH_EcNo NA Static

tReselection CellSelectionInfo Int [031] (s) 31 6 C2

35

Measurements

The different types of air interface measurements are

bull Intra-frequency measurements measurements on downlink physical channels at the same frequency as the active set A measurement object corresponds to one cell

bull Inter-frequency measurements measurements on downlink physical channels at frequencies that differ from the frequency of the active set A measurement object corresponds to one cell

bull Inter-RAT measurements measurements on downlink physical channels belonging to another radio access technology than UTRAN eg GSM A measurement object corresponds to one cell

36

Handover (Handoff) bull There are following categories of handover (also referred to as handoff)

bull Hard handover means that all the old radio links in the UE are removed before

the new radio links are established Hard handover can be seamless or non-seamless Seamless hard handover means that the handover is not perceptible to the user In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover

bull Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN Soft handover is performed by means of macro diversity which refers to the condition that several radio links are active at the same time

bull Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (ie the site of co-located base stations from which several sector-cells are served

37

Handover (Handoff) bull The most obvious cause for performing a handover is that due to its movement a user

can be served in another cell more efficiently (like less power emission less interference) It may however also be performed for other reasons such as system load control

bull Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (ie the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set)

bull The maximum active set size at the RNC is determined by the parameter MaxAciveSetSize

bull 3 to 4 cells the larger the active set size the more likely it is that Iub link efficiency is reduced (more than one resource for a single connection due to SHO)

bull Cells which are not included in the active set but are included in the CELL_INFO_LIST belong to the Monitored Set

bull Cells detected by the UE which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state

38

PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)

bull The primary cell election algorithm applies to soft HO It is used for monitored set determination and a pointer to mobility parameter

bull The Monitored Set should be updated each time the primary cell of active set changes A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set The message contains the cell to addremove from the monitored and should follow the ACIVE SET UPDATE message

bull The primary cell algorithm is called from SHO algorithm therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC

Measurement control used for monitored set update

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

28

Slot Synchronization

P-SCH1

P-SCH3

P-SCH2

P-SCH1 S-SCH1 P-CCPCH P-CCPCH

P-SCH2 S-SCH2 P-CCPCH P-CCPCH

P-SCH3 S-SCH3 P-CCPCH P-CCPCH P-CCPCH

1 Slot = 667ms

UE synchronizes on the strongest correlation peak

29

Cell Information

P-SCH Coverage indication Slot Synchronization

S-SCH Frame Synchronization Group identification

P-CPICH Scrambling Code Identification

P-CCPCH System Information Broadcast

Logical Channel

BCCH

Transport Channel

BCH

Physical Channel

P-CCPCH

OVSF Cch2561

Primary Scrambling Code

Transmitted during 910th slot

Bit Rate 123 kbps RLC Mode transparent

Mac-B transparent

30

Intra-Frequency Cell Reselection sample

Time

Quality

Serving CellServing Cell

Neighboring Cell

Neighboring Cell

Neighboring

cell criterion S

is fulfilled and is

ranked

Neighboring cell

better ranking

than Serving cell

UE perform cell

reselection

Treselections

Qmeans + Qhyst2s

Qmeann - Qoffset2sn

Qqualmin

UE perform

intra-frequency

measurements

Qqualmin +

SIntraSearch

31

Cell selection and reselection Cell Selection criteria

The cell selection criterion S is fulfilled when

where

Squal = Qqualmeas ndash Qqualmin

Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

Pcompensation ＝ max(UE_TXPWR_MAX_RACH ndash P_MAX 0)

for FDD cells Srxlev gt 0 AND Squal gt 0

for TDD cells Srxlev gt 0

for GSM cells Srxlev gt 0

32

Cell Selection Parameters

Parameter Object Range Default Value Recommended Value Class

qQualMin CellSelectionInfo Int [-240]

(dB)

-10 -16 C2

qRxLevMin CellSelectionInfo Int [-115-25]

Step = 2 (dBm)

-45 -115 C2

maxAllowedUlTxPower UlUsPowerConf Int [-5033]

(dBm)

33 33 C3

P_Max = maximum UE output power (dBm) according to its class

Power Class Maximum Output Power (dBm)

1 33

2 27

3 24

4 21

33

Cell Reselection Procedure

Squal

SintraSearch

SinterSearch

SinterRAT Measurement on

same frequency Measurement on

other frequencies Measurement on

other RAT

If Squal = CPICH_EcNo ndash qQualMin lt Threshold

Associated measurements are performed

Thresholds are broadcasted in SIB 11

In UMTS02 2 types of measurements are done Intra frequency and inter RAT

Th

rese

ho

lds

giv

en a

s ex

am

ple

34

Cell Reselection Parameters

Parameter Object Range Default Value Recommended Value Class

qHyst1 CellSelectionInfo Int [040] (dBm)

Step = 2

10 4 C2

qHyst2 CellSelectionInfo

Int [040] (dB)

Step = 2

4 6 C2

qOffset1sn GSMCell

Int [-5050] (dB) 0 TBD C0

qOffset2sn UMTSFDDNeighbouring Int [-5050] (dB) 0 TBD C0

qualMeas CPICH_EcNo or

CPICH_RSCP

CPICH_EcNo NA Static

tReselection CellSelectionInfo Int [031] (s) 31 6 C2

35

Measurements

The different types of air interface measurements are

bull Intra-frequency measurements measurements on downlink physical channels at the same frequency as the active set A measurement object corresponds to one cell

bull Inter-frequency measurements measurements on downlink physical channels at frequencies that differ from the frequency of the active set A measurement object corresponds to one cell

bull Inter-RAT measurements measurements on downlink physical channels belonging to another radio access technology than UTRAN eg GSM A measurement object corresponds to one cell

36

Handover (Handoff) bull There are following categories of handover (also referred to as handoff)

bull Hard handover means that all the old radio links in the UE are removed before

the new radio links are established Hard handover can be seamless or non-seamless Seamless hard handover means that the handover is not perceptible to the user In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover

bull Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN Soft handover is performed by means of macro diversity which refers to the condition that several radio links are active at the same time

bull Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (ie the site of co-located base stations from which several sector-cells are served

37

Handover (Handoff) bull The most obvious cause for performing a handover is that due to its movement a user

can be served in another cell more efficiently (like less power emission less interference) It may however also be performed for other reasons such as system load control

bull Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (ie the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set)

bull The maximum active set size at the RNC is determined by the parameter MaxAciveSetSize

bull 3 to 4 cells the larger the active set size the more likely it is that Iub link efficiency is reduced (more than one resource for a single connection due to SHO)

bull Cells which are not included in the active set but are included in the CELL_INFO_LIST belong to the Monitored Set

bull Cells detected by the UE which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state

38

PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)

bull The primary cell election algorithm applies to soft HO It is used for monitored set determination and a pointer to mobility parameter

bull The Monitored Set should be updated each time the primary cell of active set changes A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set The message contains the cell to addremove from the monitored and should follow the ACIVE SET UPDATE message

bull The primary cell algorithm is called from SHO algorithm therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC

Measurement control used for monitored set update

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

29

Cell Information

P-SCH Coverage indication Slot Synchronization

S-SCH Frame Synchronization Group identification

P-CPICH Scrambling Code Identification

P-CCPCH System Information Broadcast

Logical Channel

BCCH

Transport Channel

BCH

Physical Channel

P-CCPCH

OVSF Cch2561

Primary Scrambling Code

Transmitted during 910th slot

Bit Rate 123 kbps RLC Mode transparent

Mac-B transparent

30

Intra-Frequency Cell Reselection sample

Time

Quality

Serving CellServing Cell

Neighboring Cell

Neighboring Cell

Neighboring

cell criterion S

is fulfilled and is

ranked

Neighboring cell

better ranking

than Serving cell

UE perform cell

reselection

Treselections

Qmeans + Qhyst2s

Qmeann - Qoffset2sn

Qqualmin

UE perform

intra-frequency

measurements

Qqualmin +

SIntraSearch

31

Cell selection and reselection Cell Selection criteria

The cell selection criterion S is fulfilled when

where

Squal = Qqualmeas ndash Qqualmin

Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

Pcompensation ＝ max(UE_TXPWR_MAX_RACH ndash P_MAX 0)

for FDD cells Srxlev gt 0 AND Squal gt 0

for TDD cells Srxlev gt 0

for GSM cells Srxlev gt 0

32

Cell Selection Parameters

Parameter Object Range Default Value Recommended Value Class

qQualMin CellSelectionInfo Int [-240]

(dB)

-10 -16 C2

qRxLevMin CellSelectionInfo Int [-115-25]

Step = 2 (dBm)

-45 -115 C2

maxAllowedUlTxPower UlUsPowerConf Int [-5033]

(dBm)

33 33 C3

P_Max = maximum UE output power (dBm) according to its class

Power Class Maximum Output Power (dBm)

1 33

2 27

3 24

4 21

33

Cell Reselection Procedure

Squal

SintraSearch

SinterSearch

SinterRAT Measurement on

same frequency Measurement on

other frequencies Measurement on

other RAT

If Squal = CPICH_EcNo ndash qQualMin lt Threshold

Associated measurements are performed

Thresholds are broadcasted in SIB 11

In UMTS02 2 types of measurements are done Intra frequency and inter RAT

Th

rese

ho

lds

giv

en a

s ex

am

ple

34

Cell Reselection Parameters

Parameter Object Range Default Value Recommended Value Class

qHyst1 CellSelectionInfo Int [040] (dBm)

Step = 2

10 4 C2

qHyst2 CellSelectionInfo

Int [040] (dB)

Step = 2

4 6 C2

qOffset1sn GSMCell

Int [-5050] (dB) 0 TBD C0

qOffset2sn UMTSFDDNeighbouring Int [-5050] (dB) 0 TBD C0

qualMeas CPICH_EcNo or

CPICH_RSCP

CPICH_EcNo NA Static

tReselection CellSelectionInfo Int [031] (s) 31 6 C2

35

Measurements

The different types of air interface measurements are

bull Intra-frequency measurements measurements on downlink physical channels at the same frequency as the active set A measurement object corresponds to one cell

bull Inter-frequency measurements measurements on downlink physical channels at frequencies that differ from the frequency of the active set A measurement object corresponds to one cell

bull Inter-RAT measurements measurements on downlink physical channels belonging to another radio access technology than UTRAN eg GSM A measurement object corresponds to one cell

36

Handover (Handoff) bull There are following categories of handover (also referred to as handoff)

bull Hard handover means that all the old radio links in the UE are removed before

the new radio links are established Hard handover can be seamless or non-seamless Seamless hard handover means that the handover is not perceptible to the user In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover

bull Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN Soft handover is performed by means of macro diversity which refers to the condition that several radio links are active at the same time

bull Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (ie the site of co-located base stations from which several sector-cells are served

37

Handover (Handoff) bull The most obvious cause for performing a handover is that due to its movement a user

can be served in another cell more efficiently (like less power emission less interference) It may however also be performed for other reasons such as system load control

bull Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (ie the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set)

bull The maximum active set size at the RNC is determined by the parameter MaxAciveSetSize

bull 3 to 4 cells the larger the active set size the more likely it is that Iub link efficiency is reduced (more than one resource for a single connection due to SHO)

bull Cells which are not included in the active set but are included in the CELL_INFO_LIST belong to the Monitored Set

bull Cells detected by the UE which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state

38

PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)

bull The primary cell election algorithm applies to soft HO It is used for monitored set determination and a pointer to mobility parameter

bull The Monitored Set should be updated each time the primary cell of active set changes A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set The message contains the cell to addremove from the monitored and should follow the ACIVE SET UPDATE message

bull The primary cell algorithm is called from SHO algorithm therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC

Measurement control used for monitored set update

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

30

Intra-Frequency Cell Reselection sample

Time

Quality

Serving CellServing Cell

Neighboring Cell

Neighboring Cell

Neighboring

cell criterion S

is fulfilled and is

ranked

Neighboring cell

better ranking

than Serving cell

UE perform cell

reselection

Treselections

Qmeans + Qhyst2s

Qmeann - Qoffset2sn

Qqualmin

UE perform

intra-frequency

measurements

Qqualmin +

SIntraSearch

31

Cell selection and reselection Cell Selection criteria

The cell selection criterion S is fulfilled when

where

Squal = Qqualmeas ndash Qqualmin

Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

Pcompensation ＝ max(UE_TXPWR_MAX_RACH ndash P_MAX 0)

for FDD cells Srxlev gt 0 AND Squal gt 0

for TDD cells Srxlev gt 0

for GSM cells Srxlev gt 0

32

Cell Selection Parameters

Parameter Object Range Default Value Recommended Value Class

qQualMin CellSelectionInfo Int [-240]

(dB)

-10 -16 C2

qRxLevMin CellSelectionInfo Int [-115-25]

Step = 2 (dBm)

-45 -115 C2

maxAllowedUlTxPower UlUsPowerConf Int [-5033]

(dBm)

33 33 C3

P_Max = maximum UE output power (dBm) according to its class

Power Class Maximum Output Power (dBm)

1 33

2 27

3 24

4 21

33

Cell Reselection Procedure

Squal

SintraSearch

SinterSearch

SinterRAT Measurement on

same frequency Measurement on

other frequencies Measurement on

other RAT

If Squal = CPICH_EcNo ndash qQualMin lt Threshold

Associated measurements are performed

Thresholds are broadcasted in SIB 11

In UMTS02 2 types of measurements are done Intra frequency and inter RAT

Th

rese

ho

lds

giv

en a

s ex

am

ple

34

Cell Reselection Parameters

Parameter Object Range Default Value Recommended Value Class

qHyst1 CellSelectionInfo Int [040] (dBm)

Step = 2

10 4 C2

qHyst2 CellSelectionInfo

Int [040] (dB)

Step = 2

4 6 C2

qOffset1sn GSMCell

Int [-5050] (dB) 0 TBD C0

qOffset2sn UMTSFDDNeighbouring Int [-5050] (dB) 0 TBD C0

qualMeas CPICH_EcNo or

CPICH_RSCP

CPICH_EcNo NA Static

tReselection CellSelectionInfo Int [031] (s) 31 6 C2

35

Measurements

The different types of air interface measurements are

bull Intra-frequency measurements measurements on downlink physical channels at the same frequency as the active set A measurement object corresponds to one cell

bull Inter-frequency measurements measurements on downlink physical channels at frequencies that differ from the frequency of the active set A measurement object corresponds to one cell

bull Inter-RAT measurements measurements on downlink physical channels belonging to another radio access technology than UTRAN eg GSM A measurement object corresponds to one cell

36

Handover (Handoff) bull There are following categories of handover (also referred to as handoff)

bull Hard handover means that all the old radio links in the UE are removed before

the new radio links are established Hard handover can be seamless or non-seamless Seamless hard handover means that the handover is not perceptible to the user In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover

bull Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN Soft handover is performed by means of macro diversity which refers to the condition that several radio links are active at the same time

bull Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (ie the site of co-located base stations from which several sector-cells are served

37

Handover (Handoff) bull The most obvious cause for performing a handover is that due to its movement a user

can be served in another cell more efficiently (like less power emission less interference) It may however also be performed for other reasons such as system load control

bull Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (ie the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set)

bull The maximum active set size at the RNC is determined by the parameter MaxAciveSetSize

bull 3 to 4 cells the larger the active set size the more likely it is that Iub link efficiency is reduced (more than one resource for a single connection due to SHO)

bull Cells which are not included in the active set but are included in the CELL_INFO_LIST belong to the Monitored Set

bull Cells detected by the UE which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state

38

PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)

bull The primary cell election algorithm applies to soft HO It is used for monitored set determination and a pointer to mobility parameter

bull The Monitored Set should be updated each time the primary cell of active set changes A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set The message contains the cell to addremove from the monitored and should follow the ACIVE SET UPDATE message

bull The primary cell algorithm is called from SHO algorithm therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC

Measurement control used for monitored set update

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

31

Cell selection and reselection Cell Selection criteria

The cell selection criterion S is fulfilled when

where

Squal = Qqualmeas ndash Qqualmin

Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

Pcompensation ＝ max(UE_TXPWR_MAX_RACH ndash P_MAX 0)

for FDD cells Srxlev gt 0 AND Squal gt 0

for TDD cells Srxlev gt 0

for GSM cells Srxlev gt 0

32

Cell Selection Parameters

Parameter Object Range Default Value Recommended Value Class

qQualMin CellSelectionInfo Int [-240]

(dB)

-10 -16 C2

qRxLevMin CellSelectionInfo Int [-115-25]

Step = 2 (dBm)

-45 -115 C2

maxAllowedUlTxPower UlUsPowerConf Int [-5033]

(dBm)

33 33 C3

P_Max = maximum UE output power (dBm) according to its class

Power Class Maximum Output Power (dBm)

1 33

2 27

3 24

4 21

33

Cell Reselection Procedure

Squal

SintraSearch

SinterSearch

SinterRAT Measurement on

same frequency Measurement on

other frequencies Measurement on

other RAT

If Squal = CPICH_EcNo ndash qQualMin lt Threshold

Associated measurements are performed

Thresholds are broadcasted in SIB 11

In UMTS02 2 types of measurements are done Intra frequency and inter RAT

Th

rese

ho

lds

giv

en a

s ex

am

ple

34

Cell Reselection Parameters

Parameter Object Range Default Value Recommended Value Class

qHyst1 CellSelectionInfo Int [040] (dBm)

Step = 2

10 4 C2

qHyst2 CellSelectionInfo

Int [040] (dB)

Step = 2

4 6 C2

qOffset1sn GSMCell

Int [-5050] (dB) 0 TBD C0

qOffset2sn UMTSFDDNeighbouring Int [-5050] (dB) 0 TBD C0

qualMeas CPICH_EcNo or

CPICH_RSCP

CPICH_EcNo NA Static

tReselection CellSelectionInfo Int [031] (s) 31 6 C2

35

Measurements

The different types of air interface measurements are

bull Intra-frequency measurements measurements on downlink physical channels at the same frequency as the active set A measurement object corresponds to one cell

bull Inter-frequency measurements measurements on downlink physical channels at frequencies that differ from the frequency of the active set A measurement object corresponds to one cell

bull Inter-RAT measurements measurements on downlink physical channels belonging to another radio access technology than UTRAN eg GSM A measurement object corresponds to one cell

36

Handover (Handoff) bull There are following categories of handover (also referred to as handoff)

bull Hard handover means that all the old radio links in the UE are removed before

the new radio links are established Hard handover can be seamless or non-seamless Seamless hard handover means that the handover is not perceptible to the user In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover

bull Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN Soft handover is performed by means of macro diversity which refers to the condition that several radio links are active at the same time

bull Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (ie the site of co-located base stations from which several sector-cells are served

37

Handover (Handoff) bull The most obvious cause for performing a handover is that due to its movement a user

can be served in another cell more efficiently (like less power emission less interference) It may however also be performed for other reasons such as system load control

bull Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (ie the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set)

bull The maximum active set size at the RNC is determined by the parameter MaxAciveSetSize

bull 3 to 4 cells the larger the active set size the more likely it is that Iub link efficiency is reduced (more than one resource for a single connection due to SHO)

bull Cells which are not included in the active set but are included in the CELL_INFO_LIST belong to the Monitored Set

bull Cells detected by the UE which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state

38

PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)

bull The primary cell election algorithm applies to soft HO It is used for monitored set determination and a pointer to mobility parameter

bull The Monitored Set should be updated each time the primary cell of active set changes A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set The message contains the cell to addremove from the monitored and should follow the ACIVE SET UPDATE message

bull The primary cell algorithm is called from SHO algorithm therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC

Measurement control used for monitored set update

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

32

Cell Selection Parameters

Parameter Object Range Default Value Recommended Value Class

qQualMin CellSelectionInfo Int [-240]

(dB)

-10 -16 C2

qRxLevMin CellSelectionInfo Int [-115-25]

Step = 2 (dBm)

-45 -115 C2

maxAllowedUlTxPower UlUsPowerConf Int [-5033]

(dBm)

33 33 C3

P_Max = maximum UE output power (dBm) according to its class

Power Class Maximum Output Power (dBm)

1 33

2 27

3 24

4 21

33

Cell Reselection Procedure

Squal

SintraSearch

SinterSearch

SinterRAT Measurement on

same frequency Measurement on

other frequencies Measurement on

other RAT

If Squal = CPICH_EcNo ndash qQualMin lt Threshold

Associated measurements are performed

Thresholds are broadcasted in SIB 11

In UMTS02 2 types of measurements are done Intra frequency and inter RAT

Th

rese

ho

lds

giv

en a

s ex

am

ple

34

Cell Reselection Parameters

Parameter Object Range Default Value Recommended Value Class

qHyst1 CellSelectionInfo Int [040] (dBm)

Step = 2

10 4 C2

qHyst2 CellSelectionInfo

Int [040] (dB)

Step = 2

4 6 C2

qOffset1sn GSMCell

Int [-5050] (dB) 0 TBD C0

qOffset2sn UMTSFDDNeighbouring Int [-5050] (dB) 0 TBD C0

qualMeas CPICH_EcNo or

CPICH_RSCP

CPICH_EcNo NA Static

tReselection CellSelectionInfo Int [031] (s) 31 6 C2

35

Measurements

The different types of air interface measurements are

bull Intra-frequency measurements measurements on downlink physical channels at the same frequency as the active set A measurement object corresponds to one cell

bull Inter-frequency measurements measurements on downlink physical channels at frequencies that differ from the frequency of the active set A measurement object corresponds to one cell

bull Inter-RAT measurements measurements on downlink physical channels belonging to another radio access technology than UTRAN eg GSM A measurement object corresponds to one cell

36

Handover (Handoff) bull There are following categories of handover (also referred to as handoff)

bull Hard handover means that all the old radio links in the UE are removed before

the new radio links are established Hard handover can be seamless or non-seamless Seamless hard handover means that the handover is not perceptible to the user In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover

bull Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN Soft handover is performed by means of macro diversity which refers to the condition that several radio links are active at the same time

bull Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (ie the site of co-located base stations from which several sector-cells are served

37

Handover (Handoff) bull The most obvious cause for performing a handover is that due to its movement a user

can be served in another cell more efficiently (like less power emission less interference) It may however also be performed for other reasons such as system load control

bull Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (ie the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set)

bull The maximum active set size at the RNC is determined by the parameter MaxAciveSetSize

bull 3 to 4 cells the larger the active set size the more likely it is that Iub link efficiency is reduced (more than one resource for a single connection due to SHO)

bull Cells which are not included in the active set but are included in the CELL_INFO_LIST belong to the Monitored Set

bull Cells detected by the UE which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state

38

PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)

bull The primary cell election algorithm applies to soft HO It is used for monitored set determination and a pointer to mobility parameter

bull The Monitored Set should be updated each time the primary cell of active set changes A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set The message contains the cell to addremove from the monitored and should follow the ACIVE SET UPDATE message

bull The primary cell algorithm is called from SHO algorithm therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC

Measurement control used for monitored set update

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

33

Cell Reselection Procedure

Squal

SintraSearch

SinterSearch

SinterRAT Measurement on

same frequency Measurement on

other frequencies Measurement on

other RAT

If Squal = CPICH_EcNo ndash qQualMin lt Threshold

Associated measurements are performed

Thresholds are broadcasted in SIB 11

In UMTS02 2 types of measurements are done Intra frequency and inter RAT

Th

rese

ho

lds

giv

en a

s ex

am

ple

34

Cell Reselection Parameters

Parameter Object Range Default Value Recommended Value Class

qHyst1 CellSelectionInfo Int [040] (dBm)

Step = 2

10 4 C2

qHyst2 CellSelectionInfo

Int [040] (dB)

Step = 2

4 6 C2

qOffset1sn GSMCell

Int [-5050] (dB) 0 TBD C0

qOffset2sn UMTSFDDNeighbouring Int [-5050] (dB) 0 TBD C0

qualMeas CPICH_EcNo or

CPICH_RSCP

CPICH_EcNo NA Static

tReselection CellSelectionInfo Int [031] (s) 31 6 C2

35

Measurements

The different types of air interface measurements are

bull Intra-frequency measurements measurements on downlink physical channels at the same frequency as the active set A measurement object corresponds to one cell

bull Inter-frequency measurements measurements on downlink physical channels at frequencies that differ from the frequency of the active set A measurement object corresponds to one cell

bull Inter-RAT measurements measurements on downlink physical channels belonging to another radio access technology than UTRAN eg GSM A measurement object corresponds to one cell

36

Handover (Handoff) bull There are following categories of handover (also referred to as handoff)

bull Hard handover means that all the old radio links in the UE are removed before

the new radio links are established Hard handover can be seamless or non-seamless Seamless hard handover means that the handover is not perceptible to the user In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover

bull Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN Soft handover is performed by means of macro diversity which refers to the condition that several radio links are active at the same time

bull Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (ie the site of co-located base stations from which several sector-cells are served

37

Handover (Handoff) bull The most obvious cause for performing a handover is that due to its movement a user

can be served in another cell more efficiently (like less power emission less interference) It may however also be performed for other reasons such as system load control

bull Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (ie the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set)

bull The maximum active set size at the RNC is determined by the parameter MaxAciveSetSize

bull 3 to 4 cells the larger the active set size the more likely it is that Iub link efficiency is reduced (more than one resource for a single connection due to SHO)

bull Cells which are not included in the active set but are included in the CELL_INFO_LIST belong to the Monitored Set

bull Cells detected by the UE which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state

38

PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)

bull The primary cell election algorithm applies to soft HO It is used for monitored set determination and a pointer to mobility parameter

bull The Monitored Set should be updated each time the primary cell of active set changes A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set The message contains the cell to addremove from the monitored and should follow the ACIVE SET UPDATE message

bull The primary cell algorithm is called from SHO algorithm therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC

Measurement control used for monitored set update

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

34

Cell Reselection Parameters

Parameter Object Range Default Value Recommended Value Class

qHyst1 CellSelectionInfo Int [040] (dBm)

Step = 2

10 4 C2

qHyst2 CellSelectionInfo

Int [040] (dB)

Step = 2

4 6 C2

qOffset1sn GSMCell

Int [-5050] (dB) 0 TBD C0

qOffset2sn UMTSFDDNeighbouring Int [-5050] (dB) 0 TBD C0

qualMeas CPICH_EcNo or

CPICH_RSCP

CPICH_EcNo NA Static

tReselection CellSelectionInfo Int [031] (s) 31 6 C2

35

Measurements

The different types of air interface measurements are

bull Intra-frequency measurements measurements on downlink physical channels at the same frequency as the active set A measurement object corresponds to one cell

bull Inter-frequency measurements measurements on downlink physical channels at frequencies that differ from the frequency of the active set A measurement object corresponds to one cell

bull Inter-RAT measurements measurements on downlink physical channels belonging to another radio access technology than UTRAN eg GSM A measurement object corresponds to one cell

36

Handover (Handoff) bull There are following categories of handover (also referred to as handoff)

bull Hard handover means that all the old radio links in the UE are removed before

the new radio links are established Hard handover can be seamless or non-seamless Seamless hard handover means that the handover is not perceptible to the user In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover

bull Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN Soft handover is performed by means of macro diversity which refers to the condition that several radio links are active at the same time

bull Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (ie the site of co-located base stations from which several sector-cells are served

37

Handover (Handoff) bull The most obvious cause for performing a handover is that due to its movement a user

can be served in another cell more efficiently (like less power emission less interference) It may however also be performed for other reasons such as system load control

bull Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (ie the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set)

bull The maximum active set size at the RNC is determined by the parameter MaxAciveSetSize

bull 3 to 4 cells the larger the active set size the more likely it is that Iub link efficiency is reduced (more than one resource for a single connection due to SHO)

bull Cells which are not included in the active set but are included in the CELL_INFO_LIST belong to the Monitored Set

bull Cells detected by the UE which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state

38

PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)

bull The primary cell election algorithm applies to soft HO It is used for monitored set determination and a pointer to mobility parameter

bull The Monitored Set should be updated each time the primary cell of active set changes A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set The message contains the cell to addremove from the monitored and should follow the ACIVE SET UPDATE message

bull The primary cell algorithm is called from SHO algorithm therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC

Measurement control used for monitored set update

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

35

Measurements

The different types of air interface measurements are

bull Intra-frequency measurements measurements on downlink physical channels at the same frequency as the active set A measurement object corresponds to one cell

bull Inter-frequency measurements measurements on downlink physical channels at frequencies that differ from the frequency of the active set A measurement object corresponds to one cell

bull Inter-RAT measurements measurements on downlink physical channels belonging to another radio access technology than UTRAN eg GSM A measurement object corresponds to one cell

36

Handover (Handoff) bull There are following categories of handover (also referred to as handoff)

bull Hard handover means that all the old radio links in the UE are removed before

the new radio links are established Hard handover can be seamless or non-seamless Seamless hard handover means that the handover is not perceptible to the user In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover

bull Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN Soft handover is performed by means of macro diversity which refers to the condition that several radio links are active at the same time

bull Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (ie the site of co-located base stations from which several sector-cells are served

37

Handover (Handoff) bull The most obvious cause for performing a handover is that due to its movement a user

can be served in another cell more efficiently (like less power emission less interference) It may however also be performed for other reasons such as system load control

bull Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (ie the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set)

bull The maximum active set size at the RNC is determined by the parameter MaxAciveSetSize

bull 3 to 4 cells the larger the active set size the more likely it is that Iub link efficiency is reduced (more than one resource for a single connection due to SHO)

bull Cells which are not included in the active set but are included in the CELL_INFO_LIST belong to the Monitored Set

bull Cells detected by the UE which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state

38

PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)

bull The primary cell election algorithm applies to soft HO It is used for monitored set determination and a pointer to mobility parameter

bull The Monitored Set should be updated each time the primary cell of active set changes A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set The message contains the cell to addremove from the monitored and should follow the ACIVE SET UPDATE message

bull The primary cell algorithm is called from SHO algorithm therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC

Measurement control used for monitored set update

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

36

Handover (Handoff) bull There are following categories of handover (also referred to as handoff)

bull Hard handover means that all the old radio links in the UE are removed before

the new radio links are established Hard handover can be seamless or non-seamless Seamless hard handover means that the handover is not perceptible to the user In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover

bull Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN Soft handover is performed by means of macro diversity which refers to the condition that several radio links are active at the same time

bull Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (ie the site of co-located base stations from which several sector-cells are served

37

Handover (Handoff) bull The most obvious cause for performing a handover is that due to its movement a user

can be served in another cell more efficiently (like less power emission less interference) It may however also be performed for other reasons such as system load control

bull Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (ie the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set)

bull The maximum active set size at the RNC is determined by the parameter MaxAciveSetSize

bull 3 to 4 cells the larger the active set size the more likely it is that Iub link efficiency is reduced (more than one resource for a single connection due to SHO)

bull Cells which are not included in the active set but are included in the CELL_INFO_LIST belong to the Monitored Set

bull Cells detected by the UE which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state

38

PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)

bull The primary cell election algorithm applies to soft HO It is used for monitored set determination and a pointer to mobility parameter

bull The Monitored Set should be updated each time the primary cell of active set changes A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set The message contains the cell to addremove from the monitored and should follow the ACIVE SET UPDATE message

bull The primary cell algorithm is called from SHO algorithm therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC

Measurement control used for monitored set update

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

37

Handover (Handoff) bull The most obvious cause for performing a handover is that due to its movement a user

can be served in another cell more efficiently (like less power emission less interference) It may however also be performed for other reasons such as system load control

bull Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (ie the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set)

bull The maximum active set size at the RNC is determined by the parameter MaxAciveSetSize

bull 3 to 4 cells the larger the active set size the more likely it is that Iub link efficiency is reduced (more than one resource for a single connection due to SHO)

bull Cells which are not included in the active set but are included in the CELL_INFO_LIST belong to the Monitored Set

bull Cells detected by the UE which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state

38

PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)

bull The primary cell election algorithm applies to soft HO It is used for monitored set determination and a pointer to mobility parameter

bull The Monitored Set should be updated each time the primary cell of active set changes A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set The message contains the cell to addremove from the monitored and should follow the ACIVE SET UPDATE message

bull The primary cell algorithm is called from SHO algorithm therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC

Measurement control used for monitored set update

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

38

PRIMARY CELL ELECTION ALGORITHM (MONITORED SET UPDATE)

bull The primary cell election algorithm applies to soft HO It is used for monitored set determination and a pointer to mobility parameter

bull The Monitored Set should be updated each time the primary cell of active set changes A measurement control message is sent (with measurement commend set to modify) is sent to the UE in order to update the monitored set The message contains the cell to addremove from the monitored and should follow the ACIVE SET UPDATE message

bull The primary cell algorithm is called from SHO algorithm therefore it is performed each time a MEASUREMENT REPORT is received by the SRNC

Measurement control used for monitored set update

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

Compressed mode

bull Compressed mode is when the mobile goes into a slotted transmit mode whereby it opens up an idle period (transmission gap) where it can monitor another carrier or technology (GSM) The impact is that to maintain the same bit rate it halves the SF and therefore increases power level causing higher interference to the network If the SF cannot be halved then the bit rate of the bearer decreases If they seem knowledgably ask them if they know what messages and events trigger and configure compressed mode onoff 2D event for on 2F for off Messages would for configuration would be RADIO BEARER RECONFIGURATION TRANSPORT CHANNEL RECONFIGFURATION or PHYSICAL CHANNEL RECONFIGURATION

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

40

Compressed Mode bull During inter-frequency handover the UErsquos must be given time to make the necessary measurements on the different WCDMA

carrier frequency 1 to 7 slots per frame can be allocated for the UE to perform this intra frequency (hard handover)

bull Why is compressed mode needed ndash In UTRAN FDD transmissionreception by the mobile is continuous no idle periods are available for monitoring other frequencies if

the UE has only a single receiver

bull How is it done ndash Transmission gaps are created in the radio frame in DL andor UL to allow the UE to switch to another frequency perform

measurements on another carrier (FDD TDD or GSM) and switch back

ndash Transmission gaps are positioned in one radio frame or at the boundary of 2 radio frames in regular intervals referred to as a transmission gap pattern sequence

bull no more than 7 slots are used in any one radio frame to create the transmission gap

bull How is it done

ndash Two approaches can be taken in creating the transmission gaps of the transmission gap pattern sequence bull Modifiy the physical layer parameters (by puncturing or spreading factor reduction) to allow all information bits to be

transmitted

bull Restrict the bit rate (by higher layer scheduling) to match the fewer available transmission slots in a compressed radio frame

ndash In both approaches the goal is to not loose transmission frames

bull Who controls it

ndash Compressed mode is under the control of the UTRAN

ndash Compressed mode is configured by the RNC per UE in the form of transmission gap pattern sequences

bull given to the UE via RRC signalling

bull given to the node B via NBAP signalling

bull a transmission gap pattern sequence is associated with a specific measurement purpose

ndash FDD measurements

ndash TDD measurements

ndash GSM initial BSIC identification GSM BSIC reconfirmation GSM RSSI measurement

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

41

Physical layer Aspects Compressed Mode Methods

bull Three methods are available to create transmission gaps ndash Puncturing additional puncturingfewer repetitions are performed compared to

normal mode bull to be used only in DL

bull to be used only in the case of mapping to fixed positions

bull scrambling and channelisation code remain unchanged

ndash Spreading Factor Reduction SF is divided by 2 bull can be used in UL and DL

bull can be used with mapping to flexible positions

bull to be used only when SFgt4

bull only 2nd DTX insertion and physical channel mapping is modified

bull may lead to channelisation code shortage and the need to use a secondary scrambling code

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

42

Cell Shakedown

bull Purpose ndash To test Call Setup (Voice and FTP) in each cell ndash To test Handoffs (Soft and Softer) between Cells ndash Verify antenna orientation ndash Primary Pilot EcIo ndash Scrambling Code for each cell ndash UE transmit power ndash Path Balance

bull Method ndash By driving clockwise and anticlockwise within a designated route

around the the base station (about 30 of the site coverage area)

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

43

Difference between Scanner data amp UE Data Collection

bull Scanner

bull Primary Common Pilot Channel (P-CPICH) scrambling code measurements

bull Continuous Wave (CW) measurements

bull Spectrum analysis

bull Synchronization Channel (SCH) code word measurements

bull UE bull DataVoiceVideo Calls bull Layer 3 messages logging bull Layer 2 messages logging (Transport channel) bull RRC State logging bull UE Transmit Power bull SIR bull Serving Cell Active Set Monitored Set bull Events bull GSM neighbor measurements

bullDifference in data collection

Antenna

Cable

Sampling

bullSolution Perform a calibration drive

An overview of cluster performance based on scanner Best Serving CPICH RSCP and EcIo measured data

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

Inner loop amp Scanner

bull In pre-launch optimization how are missing neighbors usually detected

bull Usually you use a scanner and compare the best pilots in EcIo from the scanner against that of the active set and monitored set from an active UE If there is a stronger pilot from a nearby cell that appears on the scanner but not on the UE there is a possible missing neighbor One would thenverify that the neighbor appears in defined neighbor list from the OSS

Explain Inner and Outer loop power control and who controls them If they start talking about Open and Closed Loop PC tell them you want InnerOuter Closed Loop PC Inner loop power control is performed by the NodeB to set the transmitpower of the UE and BTS to compensate for signal variations due to fading or pathloss to maintain the set SIR (occurs up to 1500 times per sec) Outer loop power control is performed by the RNC to set the target SIR based on the required BERBLER for the requested services (occurs up to 100 times per sec)

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

45

Drop after active set update

Symptom

bull Normally the observed sequent messages in the UE side are

ndash UTRAN -gt UE Active set update (to request the UE to remove a cell eg SC281)

ndash UE -gt UTRAN Active set update complete

ndash UTRAN -gt UE Measurement Control (update neighbour list)

ndash UE -gt UTRAN Measurement report (to propose to add7)

ndash UTRAN -gt UE Active set update (to request the UE to add SC 137)

ndash DROP(since no Active set update completion was sen after 12 secs )

bull The radio performances no matter DL and UL are very good

Possible solution No solution check this problem with UE vendor

bull In Soft

bull Handover the UE is connected to more than one Radio Base Station

bull (RBS) simultaneously At least one radio link is always active and

bull there is no interruption in the dataflow during the actual handover

bull The signals are received in the UE and combined in the RAKE

bull receiver to give protection against fading

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

46

SoftSofter Handover Radio Link Addition and

Radio Link Removal

ReferenceUser Description and Engineering Guidelines 751551-HSD 101 021 Uen B2

copy Ericsson AB 2003 - All Rights Reserved

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

47

Drop after active set update Cont

BLER is getting worse

RF condition

is ok

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

48

Drop after active set update Cont

No Active Set Completion was sent after Active Set Update

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

FINAL WORDS

bull For network tuning we need to relay on field measurements which require extensive drive tests

bull Finding the best possible configuration for antenna heights tilts azimuths and parameter setting for all the present cellssectors in the network and also for any new sites that might be needed to improve coverage

bull Power adjustment can also be used for network tuning but can become complicated and result in poor network performance

bull Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna

bull Neighbour definition is of prime importance in UMTS network (Soft handover gain and interference reduction) Keep neighbour list upto 20

bull Automated tools are needed that could suggest the best possible neighbour relations antenna heights and tilts by using both the field measurements and the propagation models amp simulations

bull Skilled people right methods and advanced tools are needed to perform 3G tuning and optimisation

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

If a UE is on a data call (CELL-DCH state) and there is in no activity for awhile what would you expect to see occur UE should go from CELL-DCH to CELL-FACH then if still no activity to either CELL-PCH or URA-PCH (via CELL-FACH) If they talk about inactivity timers and mention that the state goes from CELL-DCH straight to CELL-PCH or URA-PCH that is also possible Bonus they say they would see RADIO BEARER RECONFIGURATION messages when the states are changing

Name the 4 RRC Connected Modes (states) and describe the characteristics of each Cell-DCH UE has been allocated a dedicated physical channel in uplink and downlink Cell-FACH UE listens to RACH channel (DL) and is allocated a FACH channel (UL) Small amounts of ULDL data can be transfers in this state The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message Cell-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the cell level and cell reselections are possible with the CELL UPDATE message No data can be transferred in the UL in this state URA-PCH UE monitors (using discontinuous reception) a PCH channel (PCH) indicated by the PICH channel The RNC tracks the UE down to the URA level

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels

Power control

In the uplink the base station measures the received Signal-to- Interference Ratio (SIR) and compares this to a target SIR If the measured SIR is below the target then the base station requests the mobile to increase its power (and vice versa) This type of power control is known as the Inner-loop power control and is capable of adjusting the transmit power in steps of for example 1 dB at a rate of 1500 times per second Inner-loop power control is only applicable for connections on dedicated channels