huawei wcdma power planning
TRANSCRIPT
Huawei Confidential. All Rights Reserved
WCDMA Power Planning
ISSUE 1.0
Internal Use2
Power is the final radio resource in
WCDMA system. How to allocate the
power for different channel will affect the
capacity and coverage performance of
WCDMA system.
In this course, different power allocation
strategies are used for different channel
based on the structures.
Internal Use3
ObjectObject
Upon completion this course, you will be able to:
Know the power configuration analysis of
downlink channels
Know the parameters configuration of
Downlink Channel Power
Internal Use4
Power Configuration AnalysisPower Configuration Analysis
Purpose
In Downlink, all users and the common channel shared the total
transmission power in one NodeB
Because of the limited transmission power, the reasonable power
configuration for common channels and dedicated channel plays an
important role about enhancing the capacity and coverage.
Power Control
Dedicated Channel : Inner loop power control, which is needed to set the
maximum and minimum transmission power.
Common Channel: No power control, and the transmission power are set
when the cell set up.
Internal Use5
Downlink Common ChannelDownlink Common Channel
The common channel which are needed the power The common channel which are needed the power configuration are:configuration are:
CPICH
P-CCPCH
SCH(P-SCH,S-SCH)
S-CCPCH
PICH
AICH
Internal Use6
The factor which influenced powerThe factor which influenced power
Performance requirements
Different common channel requires different BLER, Eb/No or Ec/Io
Processing Gain
The channel processing gain means the gain from coding process and spreading
process during demodulation
The P-CCPCH 、 S-CCPCH have 3dB coding gain besides spreading gain
CPICH 、 PICH and AICH only have spreading gain
Since no spreading process for SCH, no spreading gain for SCH. But it is
repeated transmitted, this gain should be considered.
Propagation Environment
Different environment, the relationship between BER/BLER and Eb/Io are
different.
Internal Use7
Power configuration AnalysisPower configuration Analysis
Under the condition of satisfied the coverage requirement, the less
transmission power of each common channel, the better performance
will be get.
Different channel request different Eb/No to obtain the BER/BLER
requirements
Because different channel has different coding gain and spreading gain,
the corresponding Ec/Io will be different.
Internal Use8
The problems about parameters configurationThe problems about parameters configuration
Problems:
In protocol, the performance indices are not defined.
Each channel needs a performance index which is not mentioned in any
reference books
Internal Use9
The power configuration for dedicated channelThe power configuration for dedicated channel
The maximum transmission power for single user should satisfied:
Obtain the quality (BER/BLER) of services on the edge of cell
The coverage balance on both uplink and downlink: According to the maximum
transmission power of UE, the uplink coverage ability can be calculated. From
that, the downlink coverage ability and the coupling loss can be achieved. Then,
with the known downlink capacity, the downlink maximum transmission power for
single user can be calculated.
Internal Use10
The power configuration for Dedicated channelThe power configuration for Dedicated channel
The formula for Pmax:
Where, Lmax is the downlink maximum coupling loss, is non-
orthogonal factor, Ptot.bs the total transmission power of a NodeB,
Iother the interference caused by other base stations, Pn background
noise, Pmax the maximum transmission power for a single service,
Eb/N0 the threshold for a service
Notherbstot
b
PIL
PLP
NE
max
,
maxmax0
//
Internal Use11
The power configuration for Dedicated channelThe power configuration for Dedicated channel
The threshold of downlink transmission power for a single user
If the downlink transmission power for a single user is too strong on the
edge to cell, the downlink capacity will be decreased a lot.
Based on that, a maximum value for the downlink transmission power
for a single user should be set. This value has very close relationship
with the maximum coupling loss, the average coupling loss and the
number of users.
The lesser PmaxThreshold, the higher possibility of call drop will
happened. This value should satisfied the formula
min{Pmax , PmaxThreshold}
Internal Use12
The power configuration for common channelThe power configuration for common channel
Configuration principal:
The real cell coverage ability =min{ the common channel coverage
ability , the dedicated channel coverage ability}
the common channel coverage ability should match to the dedicated
channel coverage ability. If it is not enough, the coverage ability can not
satisfied with the services. If it is too much, it will waste the power
resource, and decrease the downlink capacity because of the increased
interference for own cell and adjacent cells
Internal Use13
The power configuration for common channelThe power configuration for common channel
Configuration method
According to the dedicated channel coverage requirement, the
maximum downlink coupling loss of common channel on the edge of cell
can be calculated.
After that, the required common channel transmission power can be
calculated according to the quality requirement of common channel.
Internal Use14
PCPICHPCPICH
Function
In the third step of cell search, it is used for finding the specific
scrambling code from scrambling group.
It decides the area of cell search, cell selection, cell re-selection and
handover.
It can be used for channel estimation while receiving.
It decides the receiving performance of other dedicated and common
channel except SCH
It decides the coverage ability of other channels.
Configuration principle
The power is decided by the cell radius and environment.
The typical value is the 5%~10% of the total power of base station
It is a reference for configuring other common channel power value.
Internal Use15
PCPICHPCPICH
Frame structure for Frame structure for CPICH CPICH
In CPICH, the transmission contents are already defined in protocol.
Tslot = 2560 chips , 20 bits
1 radio frame: Tf = 10 ms
Slot #14Slot #iSlot #1Slot #0
Pre-defined bit sequence
Internal Use16
PCPICHPCPICH
CPICH
Fixed rate,30kbps , SF=256 , No coding gain
For example, the maximum downlink transmission power for a single service is
30dBm. Considering the 3dB coding gain of dedicate channel, the CPICH
transmission power is 33dbm in order to provide the same coverage ability.
Reference configuration
The range defined in protocol: -10 .. 50dBm
Default configuration: 33dBm
MML command
ADD PCPICH
Internal Use17
The transmission power of PCPICH should satisfied the following
formula
Where PCPICH is the transmission power which base station allocated, Ec
CPICH should satisfied the normal cell search, handover and the stable
quality of dedicated channel and common channel.
After the EcCPICH and PCPICH are set, the cell coverage ability can be
obtained by the downlink maximum coupling loss Lmax
PCPICHPCPICH
0,
//
NEPI
L
PLP
cCPICH
Notherbstot
CPICH
Internal Use18
According to the downlink maximum coupling loss, the transmission
power of other channels except SCH can be calculated by the following
formula:
Where, PDLCH is the downlink transmission power of a common channel,
Ec/N0DLCH is the SIR which should satisfied the quality of the common channel
PCPICHPCPICH
)]([ 0max,0
NILPN
EP otherbstot
DLCH
cDLCH
Internal Use19
SCHSCH
P-SCH
Function
In the first step, it is used for time slot synchronization
Configuration principal
the time slot synchronization success rate should be satisfied the
requirement
S-SCH
Function
In the second step of cell search, it is used for frame synchronization and
scrambling code group identification.
Configuration principal
the frame synchronization success rate should be satisfied the requirement
Internal Use20
Synchronization Procedure—Cell SearchSynchronization Procedure—Cell Search Synchronization Procedure—Cell SearchSynchronization Procedure—Cell Search
Slot synchronization
Frame synchronization and code-group identification
Scrambling-code identification
UE uses PSC to acquire slot synchronization to a cell
UE uses SSC to find frame synchronization and identify the code group of the cell found in the first step
UE determines the primary scrambling code through correlation over the CPICH with all codes within the identified group, and then detects the P-CCPCH and reads BCH information。
Internal Use21
As for the PSCH and SSCH , the orthogonal factor do not need to be
considered because the OVSF code is not used for the channels. The
transmission power is :
Since the SCH channels is not spread, it increased the interference to other
channels.
The transmission power can not be larger. The value can be get from the
success rate of time slot synchronization, frame synchronization and
scrambling group identification.
SCHSCH
)]([ 0max,0
NILPN
EP otherbstot
SCH
cSCH
Internal Use22
SCHSCH
Structure of Synchronisation Structure of Synchronisation Channel (SCH) Channel (SCH)
PSC is a known sequence. For all cells, the PSC are same. The length is 16 chips, and it is repeated 256 times to transmitted at the first 256 chips of each time slot.
PrimarySCH
SecondarySCH
256 chips
2560 chips
One 10 ms SCH radio frame
Slot #0 Slot #1 Slot #14
ac si,0
ac p
ac si,1
ac p
ac si,14
ac p
Internal Use23
SCHSCH
SCH
No coding
The gain is from transmission repeatedly
Considering any time slot of SCH can be used for cell search and UE can restart
the process at next time slot if failed, the power of SCH can be decreased
Reference configuration
The value range defined in protocol: -35..+15dB
In the test environment defined in 25.133, the power of SCH is -2dB
Default value : -5dB
MML command
ADD PSCH
ADD SSCH
Internal Use24
P-CCPCH(BCH)P-CCPCH(BCH)
P-CCPCH(BCH)
Function
The system information is broadcasted in this channel, which is used for
the process of cell selection, cell re-selection, access , handover etc.
BCCH can only be transmitted by the TM mode. If UE can not decode
the information correctly, it will retry.
Configuration principal
The success rate of UE getting the message form BCH achieved target
value
Internal Use25
P-CCPCH(BCH)P-CCPCH(BCH)
Frame structure for Primary Common Control Frame structure for Primary Common Control Physical Channel Physical Channel
Tslot = 2560 chips , 20 bits
1 radio frame: Tf = 10 ms
(Tx OFF)
256 chips
Slot #14Slot #iSlot #1Slot #0
Data N data1=18 bits
Internal Use26
P-CCPCH(BCH)P-CCPCH(BCH)
BCH
The length of system information block is different from the different type of
information. The maximum number of TB for a integrated one can be 16.
Assume the number is 3 and the BLER is BLERPCCPCH, then the
possibility of UE getting the information correctly in the first time is p = (1-
BLERPCCPCH )3 , and the q=1- (1-BLERPCCPCH )3
Channel coding CRC length TTI
convolution 16 bit 20ms
Internal Use27
P-CCPCH(BCH)P-CCPCH(BCH)
Then the possibility of UE getting the information correctly in the N2th time at most is :
Internal Use28
P-CCPCH(BCH)P-CCPCH(BCH)
PCCPCH(BCH)
SF = 256
½ convolutional coding, so more gain can be get compare to CPICH
Reference configuration
The value range defined in protocol: -35 .. +15dB
With 3dB coding gain of P-CCPCH, the transmission power can be less
3dB than PCPICH
Default value : -2dB
MML
ADD BCH
Internal Use29
S-CCPCHS-CCPCH
Frame structure for Secondary Common Control Frame structure for Secondary Common Control Physical Channel Physical Channel
Tslot = 2560 chips , 20*2 bits ( k =0…6)
1 radio frame: Tf = 10 ms
(TFCI)N bits
256 chips
Slot #14Slot #iSlot #1Slot #0
Data N data1 bits(TFCI)
PolitN bits Polit
k
Internal Use30
S-CCPCHS-CCPCH
One cell can support 1 or 2 SCCPCH channels
SCCPCH
A.) carrier 1 PCH and 3 FACHs ( Transportation signaling, traffic data
and CTCH ); B.) carrier two FACH ( Transportation signaling, traffic data ); C.) Carrier PCH ; D.) carrier 1 PCH and 2 FACHs ( Transportation signaling, traffic data ); Etc 。
Internal Use31
S-CCPCHS-CCPCH
FACH Coding Method Rate Match CRC Length TTI
Signaling Convolution(1/2) 220 16bits 10ms
Data Turbo 130 16bits 10ms
DTCH Convolution(1/3) 220 16bits 10ms
Coding Method Rate Match CRC Length TTI
Convolution(1/2) 230 16bits 10ms
PCPCHH
FACHFACH
Internal Use32
S-CCPCH(FACH)S-CCPCH(FACH)
S-CCPCH(FACH)
Function
RRC CONNECTION SETUP message is sent on this channel by
RNC, which influenced the RRC connection establishment
Transmit low data rate service
Configuration principal:
The success rate which UE received RRC CONNECTION SETUP
achieved the target value
The BLER of data service achieve the target value
Internal Use33
S-CCPCH(FACH)S-CCPCH(FACH)
RRC connection establishment process
The RRC_CONECTION_REQUEST is sent on PRACH by UE: UE will retransmit the REQUEST message if the SETUP
message is not arrived in T300 ( the default value is 1000ms ) If the retransmitted times is beyond N300(the default value is 3) ,
the establishment failed ; RRC_CONECTION_SETUP is sent on SCCPCH by UTRAN ;
The reasons for retransmission
RRC_CONECTION_REQUEST is not received by UTRAN correctly ; RRC_CONECTION_SETUP is not received by UE ;
Internal Use34
Assume:
The possibility which UE received the RRC_CONNECTION_SETUP message
correctly is
The BLER of PRACH message part is
The number of TB of PRACH Message is 1, and the FACH one is 8
The BLER of SCCPCH is BLERFACH, then the possibility which UE
received the RRC_CONNECTION_SETUP correctly is:
Where p is the , the q is the
S-CCPCH(FACH)S-CCPCH(FACH)
3
1
13 )1(
n
n pqpqx
8)1( FACHBLER
x3
PRACHBLER
PRACHBLER1
Internal Use35
So, the lowest possibility which can receive
the RRC_Connection_Setup message for FACH can
be calculated by the following formula:
This formula means the possibility is in the worst condition
The worst situation is the three retransmission are all caused by the
FACH, and UE has to receive the RRC_Connection_Setup message
correctly on the third time
S-CCPCH(FACH)S-CCPCH(FACH)
828 )1(])1(1[ FACHFACH BLERBLER
Internal Use36
S-CCPCH(FACH)S-CCPCH(FACH)
Reference configuration
The value range : -35 ~ 15dB
Default value: -1dB
MML
ADD FACH
Internal Use37
AICHAICH
AICH
Function
AI is sent from this channel by RNC
Configuration principal
On the edge of cell, the possibility which UE can get the
AI correctly satisfies the target value
Internal Use38
AICHAICH
Structure of Acquisition Indicator Structure of Acquisition Indicator Channel (AICH) Channel (AICH)
20 ms
AS #14AS #iASt #1ASt #0AS #14 ASt #0
a0 a1 a2 a30 a31 Transmission Off
A1 part=4098 Chips,32 real-valued syTTbols 1024 Chips
Internal Use39
a0, a1, …, a31 can be calculated by the following formula:
where AIs is acquisition indicator of the sth signature , which can be +1, -1, or 0. the values corresponds to acquisition successfully, failed or no reponse (when the AI is an unusable one for corresponding signature of PRACH). The sequences bs,0, …, bs,31 is given by following table :
AICHAICH
Internal Use40
AICHAICH
If UE detected the AIS in corresponding signature is 1 , it shows the
access process succeed. Then, the UE can transmit the message part.
If UE detected the AIS in corresponding signature is -1, it shows the
access process is refused,
UE transmit the “Nack on AICH received” to MAC , Wait for ( 10ms+NB01*10ms , 3 NBO1 10 ), then try again
If UE detected the AIS in corresponding signature is 0
Retransmit a preamble with higher power, ( the power increase should less than
6dB ) If the retransmission times is beyond the maximum number or receive a right
acquisition indicator, UE exits the random access process
Internal Use41
AICHAICH
AICH
No coding
SF = 256
Reference configuration
The value range: -10 .. +5dB
In the environment defined in 25.133, the ratio of Ec of AICH to total
transmission power is -10db. That is to say, the transmission power of AICH
should be the same as the CPICH. Considering the maximum number of AI
is 16, each AI power can be only 1/16 CPICH power(-12db)
Default value : -6dB
MML
MOD AICHPWROFFSET
Internal Use42
S-CCPCH(PCH) &PICHS-CCPCH(PCH) &PICH
S-CCPCH(PCH)
Function
The paging message is sent by RNC from this channel
Configuration principal; The possibility which UE can receive it’s paging message correctly should
achieve the target value
PICH
Function
The paging indicator is sent from this channel by RNC
Configuration principal
The possibility which UE can receive it’s paging indicator correctly should
achieve the target value
Internal Use43
S-CCPCH(PCH) &PICHS-CCPCH(PCH) &PICH
Structure of Paging Indicator Channel (PICH)
Each PICH frame has NP Paging indicators, NP ( the number of paging
indications per frame ) defines how many paging indicators can be supported
in one PICH frame. UE can get this value from system information. The value of
NP can be 18 , 36 , 72 , 144 , which means the 288 bits is divided by NP ,
and each one, also means each PI, has 288/NP bits.
Internal Use44
The mapping relationship between {PI0, .., PIN-1} and PICH bits
{b0,..,b287} is shown as following table
UE can calculate which Np is corresponding to its paging indicator p
S-CCPCH(PCH) &PICHS-CCPCH(PCH) &PICH
Internal Use45
S-CCPCH(PCH) &PICHS-CCPCH(PCH) &PICH
Time intervals between PICH and SCCPCH
Internal Use46
S-CCPCH(PCH) &PICHS-CCPCH(PCH) &PICH
Assume
the paging success rate from CS domain and PS domain is
The times of retransmission from UTRAN is NrepeatRAN ; and the one
form CN is NrepeatCN
The Number of PI per frame is Np , and corresponding paging
indicator is Lp=288/Np ;
x5
Internal Use47
S-CCPCH(PCH) &PICHS-CCPCH(PCH) &PICH
In access process, the paging type on PCH is Page type 1. Each
paging message need 1 TB. Assume the BLER which UE received
the PCH message is BLERPCH , and the BER of PICH is BERPICH 。
If there is no paging response, the maximum retransmission time is
Npageall=NrepeatRAN * NrepeatCN
If the UE did not receive any paging message in a single paging
process, the reasons only could be :
Internal Use48
Not receive PICH correctly, and the possibility is
Not receive PCH correctly, and the possibility is
So the possibility which UE can not receive paging message correctly is
S-CCPCH(PCH) &PICHS-CCPCH(PCH) &PICH
LpPICHBER )1(1
PCHLp
PICHLp
PICH BLERBERBERq )1()1(1
PCHBLER
Internal Use49
S-CCPCH(PCH) &PICHS-CCPCH(PCH) &PICH
Then the success rate is p=1-q , the possibility which UE can
receive the paging message correctly after Npageall
retransmissions is:
pageallN
i
i pqx0
5
Internal Use50
PICH and PCHPICH and PCH
PICH reference configuration
The value range : -10 .. +5dB
Default configuration: -7dB
PCH reference configuration
The value range: -35 ~ 15dB
Default configuration: -2dB
MML
ADD CHPWROFFSET
ADD PCH
Huawei Confidential. All Rights Reserved