1 © Nokia Siemens Networks RN31673EN30GLA1
Course Content
Radio Resource Management Overview
Parameter Configuration
Common Channels & Power Control
Load Control
Admission Control
Packet Scheduling
Handover Control
Resource Manager
HSDPA RRM & parameters
HSUPA RRM & parameters
HSPA+ features & parameters
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Common Channels & Power Control:Module Objectives
At the end of the module you will be able to:
• Describe the DL common channels power settings
• Name and describe the different power control loops
• Explain the open loop power control (both in UL& DL), name and describe the related RAN parameters
• Describe outer loop & closed loop power control (both in UL & DL) and the relationship between them in detail
• Explain the DL Power Balancing
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Power Control
• Channel mapping
• Power Setting for DL Common Channel
• Open Loop Power Control
• Fast Closed Loop Power Control
• Outer Loop Power Control
• Optional: DL Power balancing
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Channel types and location in UTRAN
Logical Channels
Transport Channels
Physical Channels
UE
Iub Frames
RNCNode B
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Channel Mapping DL (Network Point of View)
P-CCPCH
PCH
BCH
CTCH
DCCH
CCCH
PCCH
BCCH
DCH
P-CPICH
P/S-SCHFACH
HS-DSCH
AICH
HS-PDSCH**
DPDCH
S-CCPCH
DTCH
PICH
LogicalChannels
TransportChannels
PhysicalChannels
DPCCH
HS-SCCH
E-HICH*
PowerControl
FixedPower
E-AGCH/E-RGCH*
* Power Control with RAN971 HSUPA DL Physical Channel Power Control
** Dynamic HS-PDSCH power allocation
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Channel Mapping UL (Network Point of View)
DCCH
DCH DPDCHDTCH
LogicalChannels
TransportChannels
PhysicalChannels
RACHCCCH PRACH
DPCCH
HS-DPCCHE-DCH
E-DPDCH
E-DPCCH
OpenLoop
PowerControl
PowerControl
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Example – Channel configuration during call
LogicalChannels
TransportChannels
PhysicalChannels
Data
DCCH1-4
DCH2-4
DPDCH
DTCH1 DPCCH
RRCsignalling
Speechdata
DCH1
AMR speech connection utilises multiple transport channelsRRC connection utilises multiple logical channels, signalling radio bearers
DCH5DTCH2
NRTdata
AMR speech+
NRT data
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Power Control
• Channel mapping
• Power Setting for DL Common Channel
• Open Loop Power Control
• Fast Closed Loop Power Control
• Outer Loop Power Control
• Optional: DL Power balancing
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DL Common Control Channel
• DL Common control channels must be heard over the whole cell, thus their power setting is designed for “cell edge”.
• Rel. 99 DL Common Channels do not have a power control.
• The power of the common physical channels are set relative to the CPICH
Default parameter value Power valuePtxSecSCH -3 dB 30 dBmPtxPrimaryCCPCH -5 dB 28 dBmPtxSCCPCH 1 (SF=64) 0 dB 33 dBmPtxSCCPCH 2 (SF=256) -5 dB 28 dBmPtxSCCPCH 3 (SF=128) -2 dB 31 dBmPtxPICH -8 dB 25 dBmPtxAICH -8 dB 25 dBmPtxOffsetEAGCH -5 dB 28 dBmPtxOffsetERGCH -11 dB 22 dBm
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Pilot Channel Power Setting (1/2)
Adjust CPICH transmit Power
Identify Cells with poor coverage
Identify Cells with excessive coverage
Evaluate Ec/Io and RSCP performance
PtxPrimaryCPICHWCEL; -10..50; 0.1; 33 dBm
(Range; Step; Default)(20 W sector)
• The Common Pilot Channel CPICH is used by the User Equipments for• synchronization & channel estimation purposes• handover & cell reselection decisions
• The received quality of the CPICH is quantified by its Ec/Io , the field strength by the Received Signal Code Power RSCP
• Ec is the energy per chip, Io is the noise spectral density• RSCP is the CPICH power measured in the channel bandwidth• Ec/Io provides a relative measure, RSCP provides an absolute measure
• The CPICH Ec/Io & RSCP must be sufficiently high across the entire coverage area of the network• The CPICH consumes Node B transmit power which reduces DL capacity• CPICH power must be minimized to increase DL capacity while maintaining pilot coverage• By default the CPICH consumes 2 W of the Node B power (20 W PA)
• i.e. 10% of the PA power
• CPICH power used to derive the power of the other DL Common Control Channels• The CPICH should be tuned per cell
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Pilot Channel Power Setting (2/2)
• In terms of coverage and capacity, the WCEL: PtxPrimaryCPICH has only a very small optimal window:
• The minimum value maximises capacity (minimises coverage). • The maximum value maximises coverage (minimises capacity).
35 dBm 16 % 32 %34 dBm 13 % 26 %33 dBm 10 % 20 % (Default)32 dBm 8 % 16 % 31 dBm 6 % 12 %30 dBm 5 % 10 %
+2 dB+1 dB+0 dB-1 dB-2 dB-3 dB
% of 20W PA
% of 10W PA
CPICH power = 36 dBm is also
possible with 40W amplifiers
PtxPrimaryCPICHWCEL; -10..50; 0.1; 33 dBm
(Range; Step; Default)
(20 W sector)
• Transmitted power WCEL: PtxPrimaryCPICH should be 5%-10% of the total Tx Power for a 20W sector; Value = [-10 … 50] dBm, step 0.1 dBm
• The default value is 33dBm (2W) for 20W cell
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Effects of CPICH Power modification
CPICH Transmit Power
Increased soft handover overhead
Too much
power
Too little
power
Less Power Available for traffic
CPICH coverage holes
code detection
Unreliable channel estimation
Early cell reselection /handover
Increased Eb/No requirement
Reduced system capacity
Reduced system capacity
Reduced system coverage
Slow initial synchronization
Non- ideal traffic distribution
Late cell reselection /handover
Non- ideal traffic distribution
CPICH Transmit Power
Increased soft handover overhead
Less Power Available for traffic
CPICH coverage holes
Unreliable scrambling code detection
Unreliable channel estimation
Early cell reselection /handout too early
Increased Eb/No requirement
Reduced system capacity
Reduced system capacity
Reduced system coverage
Slow initial synchronization
Non- ideal traffic distribution
Late cell reselection /handout too late
Non- ideal traffic distribution
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SCH & P-CCPCH Power Setting
Primary Synchronisation Channel P-SCHused for DL slot (10ms/15) synchronisationP-SCH Tx power relative to CPICH.• Comments: optimal value allows decoding of the channel at the cell edge
Secondary Synchronisation Channel S-SCHused for DL Frame (10ms) synchronisationS-SCH Tx power relative to CPICH.• Comments: optimal value allows decoding of the channel at the cell edge
Primary Common Control Physical Channel P-CCPCH carries the BCH (Broadcast Channel) transport channel is a fixed rate (15 ksps, SF = 256) DL physical channel used to carry the BCHIt is a pure data channel and characterized by a fixed channelization code (Cch,256,1)It is broadcast over the entire cell and it is not transmitted during the first 256 chips of each slot, where P- SCH & S-SCH are transmittedP-CCPCH power relative to the CPICH power
PtxPrimarySCHWCEL; -35..15; 0.1; -3 dB
(Range; Step; Default)
PtxSecSCHWCEL; -35..15; 0.1; -3 dB
(Range; Step; Default)
PtxPrimaryCCPCHWCEL; -35..15; 0.1; -5 dB
(Range; Step; Default)
2560 Chips256 Chips
P-CCPCH
S-SCH
P-SCH
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Secondary CCPCH (1/6): Number of S-CCPCHs
• The Secondary Common Control Physical Channel S-CCPCH carries FACH & PCH transport channels
• NbrOfSCCPCHs: “Number of SCCPCHs” tells how many SCCPCHs will be configured for the cell. (1, 2 or 3)
• If only 1 SCCPCH is used in a cell, it will carry FACH-c (containing DCCH/CCCH /BCCH), FACH-u (containing DTCH) & PCH. FACH & PCH multiplexed onto the same SCCPCH.
• If 2 SCCPCHs are used in a cell, the 1st SCCPCH will carry FACH-u & FACH-c and the 2nd SCCPCH will always carry PCH only.
• If 3 SCCPCHs are used in a cell, the 3rd SCCPCH will carry FACH-s (containing CTCH) & FACH-c idle (containing CCCH & BCCH). The 3rd SCCPCH is only needed when Service Area Broadcast (SAB) is active in a cell.
NbrOfSCCPCHsWCEL; 1..3; 1; 1
(Range; Step; Default)
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Secondary CCPCH (2/6): Configuration 1
• If only 1 SCCPCH is used in a cell, it will carry FACH-c (containing DCCH/CCCH /BCCH), FACH-u (containing DTCH) and PCH. FACH and PCH multiplexed onto the same SCCPCH.
• the PCH bit rate is limited to 8 kbps
• the PCH always has priority
• the SF for SCCPCH, which is carrying FACH (with or without PCH), is 64 (60ksps)
Logical channel
Transport channel
Physical channel
DTCH DCCH CCCH BCCH PCCH
FACH-u FACH-c PCH
SCCPCH 1
SF 64
PtxSCCPCH1Transmission Power of SCCPCH1
WCEL; -35..15; 0.1; 0 dB
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Secondary CCPCH (3/6): Configuration 2 a & b
• If 2 SCCPCHs are used in a cell, the first SCCPCH will carry FACH-u & FACH-c and the second SCCPCH will always carry PCH only.
• PCH bit rate limited to 8 kbps (RU10 & earlier) or can be extended
to 24 kbps (RU20 feature RAN 1202: 24 kbps Paging Channel)
• if PCH24kbps enabled, NbrOfSCCPCHs must be set to “2” or “3”
• if SAB Support with 2 SCCPCH enabled, SAB can be used with NbrOfSCCPCHs = “2”
Logicalchannel
Transportchannel
Physicalchannel
DTCH DCCH CCCH BCCH PCCH
FACH-u FACH-c/s PCH
SCCPCH 1 SCCPCH 2
SF 64 SF 256
PCH24kbpsEnabledWCEL; 0 (Disabled), 1 (Enabled);
default: 0 (Disabled)
SF 128or
PtxSCCPCH2used for 8 kbps paging
WCEL; -35..15; 0.1; -5 dB
PtxSCCPCH2SF128used for 24 kbps paging
WCEL; -35..15; 0.1; -2 dB
CTCH
For SABFor SAB
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Logical channel
Transport channel
Physical channel
DTCH DCCH CCCH BCCH CTCH
FACH-u PCHFACH-s
SCCPCH connected
SCCPCH idle
PCCH
FACH-c FACH-c
SCCPCH page
For SABFor SAB
Secondary CCPCH (4/6): Configuration 3a & b• If 3 SCCPCHs are used in a cell, the 3rd SCCPCH will carry FACH-s (containing CTCH) & FACH-c
idle (containing CCCH & BCCH). The 3rd SCCPCH is only needed when Service Area Broadcast (SAB) is active in a cell.
SF 64 SF 128 SF 256
SF 128orPtxSCCPCH3
WCEL; -35..15; 0.1; -2 dB
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Secondary CCPCH (5/6): Summary Power Setting • The power of SCCPCHs are set relative to CPICH transmission power, but it is based on the bitrate.
• The SF for SCCPCH, which is carrying FACH (with or without PCH), is 64 (60ksps)
• The SF for SCCPCH, which is carrying PCH only is 256 (15ksps) or 128 (30ksps)
• The SF for SCCPCH, which is carrying FACH-s/FACH-c idle for SAB, is 128 (30ksps)
• Recommended value of the SCCPCH Tx power is depended on the number of SCCPCHs:
• WCEL: PtxSCCPCH1 (SF=64) for PCH/FACH or standalone FACH
• WCEL: PtxSCCPCH2 (SF=256) for Standalone PCH (8 kbps paging)
• WCEL: PtxSCCPCH2SF128 (SF=128) for Standalone PCH (24 kbps paging)
• WCEL: PtxSCCPCH3 (SF=128) for SAB
PtxSCCPCH1WCEL; -35..15; 0.1; 0 dB
(Range; Step; Default)
PtxSCCPCH3WCEL; -35..15; 0.1; -2 dB
SF: Spreading Factor
PtxSCCPCH2used for 8 kbps paging
WCEL; -35..15; 0.1; -5 dB
PtxSCCPCH2SF128used for 24 kbps paging
WCEL; -35..15; 0.1; -2 dB
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Secondary CCPCH (6/6): Power offset for TFCI
• At setup or reconfiguration, the BS is given the SCCPCH power offset information (PO1 for TFCI bits). The TFCI bits are transmitted irrespective of whether or not there is data transmitted.
WCEL: PowerOffsetSCCPCHTFCI (child parameters: PO1_15, PO1_30, PO1_60)
this parameter defines the power offset of the TFCI bits relative to the power of the data field; the power offset shall vary in time according to the bit rate of the SCCPCHRange: [0…6] dB step 0.25 dB
Default:PO1_15 2 dB for the 15ksps (SF=256)
PO1_30 3 dB for the 30ksps (SF=128)
PO1_60 4 dB for the 60ksps (SF=64)
PO1 is power offsetof TFCI relative for the
power of data field.T slot = 2560 chips
Data
PO1
DL transmission
Power
TFCI
The higher the SCCPCH data rates, the more important it is to correctly read TFCI
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PICH power setting• The PICH is transmitted constantly and it carries the Paging Indicators (PI) which the UE reads to find out
whether there is paging in the paging group which it belongs to.
• The number of paging indicators (paging groups) in PICH is a parameter. Smaller number means that there is more repetition in the paging symbols => less DL transmit power is needed BUT UE has to decode the paging message more often (higher battery consumption)
• Parameters to be optimised:
• WCEL: PtxPICH: Power of the PICH relative to the CPICH power• [-10 … 5] dB, step 1 dB, default depends on PI_Amount:
-10 dB for 18 and 36 PI/frame-8 dB for 72 PI/frame-5 dB for 144 PI/frame
• Related parameters:• WCEL: Pi_amount: Number of paging indicators in a frame, 18, 36, 72 or 144
(the repetition of PICH bits is 16, 8, 4 and 2 correspondingly)
• WCEL: UTRAN_DRX_length: [80; 160; 320; 640; 1280; 2560; 5120] ms. The DRX cycle length used by UTRAN to count paging occasions for discontinuous reception.
• IuCS & IuPS: CNDRXLength; CN domain specific DRX cycle length [640; 1280; 2560; 5120] ms. The DRX cycle length used by UTRAN to count paging occasions for discontinuous reception.
288 bit/frame
PtxPICHWCEL; -10..5; 1; -8 dB
(Range; Step; Default)
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PICH power optimisation
The larger the value of Pi_amount, the
• more paging groups are created per frame (the fewer the number of mobiles per group)
• less PIs are repeated per paging group and frame
• less often the UE is paged and it has to listen the SCCPCH (PCH) (leading to lower mobile power consumption but longer call setup time)
• less bits used for one paging indicator the more power for the PtxPICH
Morepower
for PICH
Morepower
for PICH
MoreUsersPer PI
MoreUsersPer PI
Pi_amount = 18 => 16 bits in PICH are used to indicate one PI is "active" , 18*16 = 288Pi_amount = 36 => 8 bits in PICH are used to indicate one PI is "active" , 36*8 = 288Pi_amount = 72 => 4 bits in PICH are used to indicate one PI is "active" , 72*4 = 288Pi_amount = 144 => 2 bits in PICH are used to indicate one PI is "active" , 144*2 = 288
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AICH power setting
• AICH is carrying the Acquisition Indicators (AI) to reply to RACH pre-ambles. All together 16 AI can be multiplexed on one access slot in AICH.
• The parameter to be optimized:
WCEL: PtxAICH, the AICH Tx power is relative to CPICH.
Range: [-22 … 5] dB, step 1dB, default -8 dB
• Related parameters: PRACH parameters including PRACH_preamble_retrans, if AI power is too low for UE to decode, it keeps sending preambles until the PRACH_preamble_retrans is exceeded (see Open Loop Power Control).
PtxAICHWCEL; -22..5; 1; -8 dB
(Range; Step; Default)
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Total DL Common Channel Power without HSPA
Service Type
DefaultPower
MinimumActivity
Minimum Average
Power
Maximum Activity
Maximum Average
Power
CPICH 33 dBm 100 % 33 dBm 100 % 33 dBm
P-SCH 30 dBm 10 % 20 dBm 10 % 20 dBm
S-SCH 30 dBm 10 % 20 dBm 10 % 20 dBm
P-CCPCH 28 dBm 90 % 27.5 dBm 90 % 27.5 dBm
S-CCPCH 33 dBm 25 % 27 dBm 115 %* 33.6 dBm
PICH 25 dBm 96 % 24.8 dBm 96 % 24.8 dBm
AICH 25 dBm 0 % - 80 % 24 dBm
Total - - 35.5 dBm3.5 W
- 37.5 dBm5.6 W
* S-CCPCH control (TFCI) bits transmitted with higher power than data bits
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Power Control
• Channel Mapping
• Power Setting for DL Common Channel
• Open Loop Power Control
• Fast Closed Loop Power Control
• Outer Loop Power Control
• Optional: DL Power balancing
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UL Outer LoopPower Control
Open Loop Power Control(Initial Access)
(Fast) Closed Loop Power Control
RNCBS
MS
DL Outer LoopPower Control
Power Control types
BLER target
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Power control during the call setup
Ptx
Time
UL: First RACH Preamble
power
UL: Power ramp-up
0PmpP
DL: Ack on AICH
UL: RACH data
Initial power of DPCH
CL & OL PC
DL: FACH
PRACH OpenLoop PC DPCH Open
Loop PCCL: Closed LoopOL: Outer Loop
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CPICH Power setting / Effect of MHA & CableLoss parameters
WBTS
MHA
Relevant DL pathloss
Relevant UL pathloss
Feeder loss
• UL & DL path losses differ by feeder loss• UE needs UL path loss for proper setting of initial PRACH
power, but measures DL path loss as:
Broadcasted CPICH TX power – CPICH RX power• CableLoss parameter reduces the broadcasted value of
CPICH TX power, thus UE path loss estimation is correct for UL
CableLossWCEL: 0..100; 0.1; 3 dB
MHAMast Head Amplifier used; WCEL;
Offset not used (0), Offset used (1)(Range & Default)
If MHA = “Offset not used” ⇒ Primary CPICH TX power = PtxPrimaryCPICH
If MHA = “Offset used” ⇒ Primary CPICH TX power = MAX(PtxPrimaryCPICH – CableLoss, CPICHMin)
• It is possible to change the SIB5 IE P-CPICH Tx power through parameters MHA & CableLoss as below:
CPICHMin: min. value allowed for IE Primary CPICH TX
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PRACH Open Loop PC• Purpose: To set the initial transmitted power of PRACH UL.
• UE determines the UL preamble power of PRACH
• UE PRACH First Preamble Power =
• Open loop PC is a part of the random access procedure for PRACH channel• For the accuracy of the UE Open Loop measurement, it is safest to start from a low power and increase it gradually
until the acquisition is received.
Path loss calculatio
ns
Path loss calculatio
ns
Minimum received power at
BTS
Minimum received power at
BTS
Transmission power of CPICH (Broadcast on BCH, SIB 5)) -
DL RSCP measurement from active cell on CPICH (Measured by UE) +
Total received wideband interference power at WCDMA BTS (Broadcast on BCH, SIB 7) +
PRACH Required Received C/I at the WCDMA BTS (Broadcast on BCH, SIB 5)
PRACHRequiredReceivedCI WCEL: -35..-10; 1; -25 dB
(Range, Steps; Default)
PRACHRequiredReceivedCI: • WCEL: range: -35..-10 dB; steps: 1.0 dB; default: -25 dB• This UL required received C/I value is used by the UE to calculate the initial output power on PRACH according to the Open Loop Power Control procedure.• If the value is too low then the RACH preamble ramping up takes a too long time. If it is too high, then it may cause blocking or high noise rise at BTS since the UE measurement on RSCP code power has a poor accuracy. • This parameter can impact on the RACH coverage.
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Random Access Procedure
p-m
p-p
Message part
PRACHaccessslots TX atUE
1 access slot
p-a
Acq.Ind.
AICHaccessslots RX atUE
P0
Pp-m
Pre-amblePre-
amble
DL
UL
TS 25.211:
Preamble-to-Preamble distance p-p p-p,min = 6 / 8 Slots
Preamble-to-AI distance p-a = 3 / 4 Slots
Preamble-to-Message distance p-m = 6 / 8 Slots
Broadcasted by P-CCPCH; NSN (WCEL):
AICHTraTime = 0, 1; 0
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Random Access Procedure
Downlink / BSDownlink / BS
Preamble 1 Message part
…. ….
Preamble n
PRACH_preamble_retrans: The maximum number of preambles allowed in 1 preamble ramping cycle
RACH_tx_Max: # of preamble power ramping cycles that can be done
before RACH transmission failure is reported,
UEtxPowerMaxPRACH WCEL: -50..33; 1; 21 dBm
PRACH_preamble_retrans WCEL: 1..64; 1; 8
PowerRampStepPRACHpreamble
WCEL: 1..8; 1; 2 dB
Uplink / UEUplink / UE
PowerOffsetLastPreamble
PRACHmessageWCEL:
-5..10; 1; 2 dB
RACH_tx_Max WCEL: 1..32; 1; 8
(Range, Steps; Default)
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Random Access Procedure
• The power ramp-up process will continue until 1) A positive AI is received from the network Send RACH message2) A negative AI is received from the network Exit RACH procedure
3) PRACH_preamble_retrans value is exhausted ((WCEL)(1…64)( = 1)(8))
4) TX power exceed UEtxPowerMaxPRACH value by > 6dB Exit RACH procedure(WCEL)(-50dBm…33dBm)( = 1dBm)(21dBm)
• When the PRACH_preamble_retrans value is exhausted, PRACH preamble power will be re-set to the initial value of the cycle and a new power ramp-up cycle initiated. The preamble power ramp-up cycle will be repeated RACH_tx_Max times. At this stage the UE will send a RACH failure message to the UE MAC layer.
• The maximum allowed UE transmit power for the PRACH procedure is defined by UEtxPowerMaxPRACH. Layer 1 of the UE controls the UE transmit power during the PRACH procedure using the ‘commanded transmit power’. If the commanded transmit power exceeds the maximum allowed transmit power then the UE transmits the maximum allowed transmit power.
• If the commanded transmit power exceeds the maximum allowed transmit power by 6 dB then layer 1 of the UE is able to inform higher layers and exit the PRACH procedure. If the step size is 1 dB then this corresponds to transmitting 6 preambles at maximum power.
• As RU10 supports SIB4, UEtxPowerMaxPRACHConn applies in Connected Mode
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PRACH Open Loop PC Parameters
Algorithm Parameters Group Default
Open Loop Power Control
PRACHRequiredReceivedCI WCEL -25 dB
PowerOffsetLastPreamblePRACHmessage WCEL 2 dB
PowerRampStepPRACHpreamble WCEL 2 dB
PRACH_preamble_retrans WCEL 8
RACH_tx_Max WCEL 8
UEtxPowerMaxPRACHConn WCEL 21 dBm
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Power Control
• Channel Mapping
• Power Setting for DL Common Channel
• Open Loop Power Control
• Fast Closed Loop Power Control
• Outer Loop Power Control
• Optional: DL Power balancing
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Uplink power control target
• Minimise required UL received power minimised UL transmit power and interference
UE1 UE2
Ptx1
Ptx1
- solve Near-Far Problem !- reduce Interference- stabilize transmission/ reduce required Eb/No optimize Capacity
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• The closed loop power control scheme is fast enough to follow multipath fading for a wide range of mobile speeds
• Received Eb/No can be kept stable but on the other hand transmitted power is peaky
• => Received Eb/No can be kept low in spite of multipath fading, but fading margin must be added to transmitted powers
0 200 400 600 800-20
-15
-10
-5
0
5
10
15
20
Time (ms)
Rel
ati
ve
po
wer
(d
B)
Channel Transmitted powerReceived power
Fast closed loop power control
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MS sets the power on UL DPCCHand UL DPDCH on following way:
TPC = '1' --> increase power by 1 dBTPC = '0' --> decrease power by 1 dB
UL DPCCH
MS
Measure received SIR on UL DPCCH Pilot
Compare measured SIR withSIR target value received from
UL outer loop PC
Measured SIR < SIR target --> TPC bit = '1'Measured SIR => SIR target --> TPC bit = '0'
BS
Send TPC bit on DL DPCCH
Changed power on UL DPCCH
UL Closed loop power control
• UL fast closed loop PC shall be active as soon as the frame synchronization has been established in the dedicated physical channels.
• PC frequency 1500 Hz
• PC step 1dB
• PC delay approx. one slot
• In Soft(er) HO power is increased only, if all (reliable) TPC bits are 1
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UL PC Algorithm
• UE adjusts the DPCCH power by DPCCH = TPC TPC_cmd.
• Power control step size TPC is fixed to 1 dB in NSN RAN
• When a UE is not in soft(er) handover, only 1 TPC command will be received in each slot.
In this case, the value of TPC_cmd shall be derived as follows:
- If the received TPC command is equal to 0, then TPC_cmd for that slot is –1.
- If the received TPC command is equal to 1, then TPC_cmd for that slot is 1.
Every TS 1 dB up or down
• If the UE is in Soft(er) handover:• UE measures SIR for all the cells in the active set
• if SIR is sufficiently large, the TPC is considered reliable
• if only one of the reliable TPC bits is 0, the UE transmission power is decreased
• only if all reliable TPC are 1 the power in increased
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DL Fast Closed Loop PC: UTRAN behaviour
UE
Measured SIR < SIR target --> TPC command is "1"
Measured SIR => SIR target --> TPC command is "0"
Compare measured SIR with SIR target
value received from DL outer loop PC
Measure received SIR on DL DPCCH
WCDMA BTS
BS sets the power on DL DPCCH andDL DPDCH following way:
TPC command = "1" --> increase power by 1 dBTPC command = "0" --> decrease power by 1 dB
DL DPCCH + DPDCHs
Send TPC command on UL DPCCH
Changed power on DL DPCCH + DPDCHs
• Upon receiving the TPC commands BS adjusts its DL DPCCH/DPDCH power accordingly.
• UTRAN shall estimate the transmitted TPC command TPCest to be 0 or 1, and shall update the power every slot.
• After estimating the k:th TPC command, UTRAN shall adjust the current DL power P(k-1) [dB] to a new power P(k) [dB] according to the following formula:
P(k) = P(k - 1) + PTPC(k) + Pbal(k)
where PTPC(k) is the k:th power adjustment due to the inner loop power controlPbal(k) is the k:th power correction due to Power balancing procedure
DownlinkInnerLoopPCStepSize
DownlinkInnerLoop PCStepSize
RNAC: 0.5..2; 0.5; 1 dB(Range, Steps; Default)
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Gain of Fast Power Control PC
• Speech performance FER= 1% (8kbps 10ms interleaving) with 2 branch receiver antenna diversity in UL
• Slow PC = no PC in simulations = correct average power
Slow power control Fast 1.5kHz power control
Gain from fast power control
ITU Pedestrian A 3 km/h 11.3dBm 7.7dBm 3.6dB
ITU Vehicular A 3 km/h 8.5dBm 7.5dBm 1.0dB
ITU Vehicular A 50 km/h 6.8dBm 7.6dBm -0.8dB
• The gain from the fast PC is larger for low mobile speeds than for high mobile speeds in received powers than in transmitted powers if only little multipath diversity is available
• the less diversity there are, the higher is the average Tx power.
• Fast PC allows to reduce Eb/No values by reducing fading effects
• The drawback of the fast PC algorithm is a rise of average TX power
Transmittedpower
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Power Control
• Channel Mapping
• Power Setting for DL Common Channel
• Open Loop Power Control
• Fast Closed Loop Power Control
• Outer Loop Power Control
• Optional: DL Power balancing
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BS RNC
UL Outer Loop Power Control
• Outer PC loop is performed to adjust the TARGET SIR in BS/UE, according to the needs of individual radio link. Required SIR depends on
• UE speed• Changes in the propagation conditions• Available multipath diversity• UE power control dynamics (close to peak power)• SHO branches (Macro Diversity Combining)
• SIR is constantly adjusted in order to maintain a constant QUALITY, usually defined as a certain BLER target of the transport channel
• BLER is measured for each transport channel separately
DL Outer LoopPower Control
Outer Loop Power Control
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UL OLPC
UL OuterLoop PCEntity #N
UL OuterLoop PCEntity #1
UL Outer Loop PCController
RNC
BTS 1UL Fast Closed
Loop PC
BTS 2UL Fast Closed
Loop PC
UL Outer Loop PC• In the RNC the functionality of the UL outer loop PC
is divided into two parts:
- UL outer loop PC Controller, one for each RRC
connection
- UL outer loop PC Entities, one for each
transport channel multiplexed in the same RL
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UL OLPC Entities & Controller
• There is one UL outer loop PC Entity for each transport channel in the RNC.
• This UL OLPC Entity calculates the required change in SIR Target according to UL quality estimates (CRC).
• One of UL OLPC Entities under the same radio link is selected to transmit the New SIR Target to the WCDMA BTS.
• An UL Outer Loop PC Controller controls all UL OLPC Entities under the same RRC connection.
• The UL OLPC Controller sets the parameters for each UL OL PC Entities at the RAB Setup/Modification.
• The UL OLPC Controller also combines SIR Target changes from the UL OLPC Entities and sends the result to the UL OLPC Entity, which is selected to transmit it to the WCDMA BTS.
UL OuterLoop PCEntity #N
UL OuterLoop PCEntity #1
UL Outer Loop PCController
RNC
BTS 1UL Fast Closed
Loop PC
BTS 2UL Fast Closed
Loop PC
UL Outer Loop PC
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Uplink OLPC Algorithm
1. RAB Setup:Initial SIR Target
UL Outer Loop PC Entity #n
UL Outer Loop PC Controller
2. - PC Parameters - Initial SIR target
8. Collection of the SIR target changes and calculation of new SIR Target
3. Setting of the UL Outer Loop PC Entities
2. PC Parameters at RAB setup
9. New SIR Target, active PC Entity
BTS1. SIR Target
1. UL fast closed loop PC
Admission Control
- Entity selected to carry the “active” flag
- Activity reporting period
4. - PC parameters
6. Calculation of SIR Target change
4. Parameters 7. SIR Target modification command
5. Quality info: BER, BLER
5. L1 FP: UL quality info
10. New SIR Target
10. L1 FP: SIR Target
10. Transmission of new SIR Target value to MDC
MDC
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UL OLPC SIR target change• The algorithm for calculating the change of SIR Target is based on BLER estimation
Where:
And:
dB nTarget SIRnTarget SIR )()1( dB nTarget SIRnTarget SIR )()1(
)_(*_ tBLER_targeestimationBLERsizestep )_(*_ tBLER_targeestimationBLERsizestep
n_of_TBlstotal
RCsn_of_nok_CationBLER_estim
_
n_of_TBlstotal
RCsn_of_nok_CationBLER_estim
_
• This calculation is completed every TTI. This limits the resolution of the BLER estimation. For example, the speech service includes a single CRC per TTI and so the BLER estimate is either 0 % or 100 %.
• If the BLER target is 1 % then the SIRTarget is increased by the step size * 0.99 or decreased by the step size * 0.01, i.e. the SIR target tends to increase more rapidly than it decreases
• Data services have multiple CRC per TTI and can achieve a greater BLER estimate resolution• step_size is given by RNC: StepSizeForDCHBLER ((0.1…1dB)(0.1dB)(0.3dB)• RAN2886 Faster OLPC introduces new parameters for OLPC SIR Target change algorithm:
• Faster OLPC step size of SIR target changes RNAC: FOLPCStepSizSIRTgt ((0.1…1dB)(0.1dB)(0.1dB) defines minimum Δ[dB] that UL NRT return channel can request
• Faster OLPC SIR target modification interval RNAC: FOLPCSIRTgtModInt ((100..700 ms)(100ms)(200ms)defines the minimum interval between two SIR target modification commands sent by OLPC entity of UL NRT return channel
StepSizeForDCHBLERRNAC: 0.1..1; 0.1; 0.3 dB
(Range, Steps; Default)
FOLPCStepSizSIRTgtused for Faster OLPC
RNAC: 0.1..1; 0.1; 0.1 dB(Range, Steps; Default)
FOLPCSIRTgtModInt used for Faster OLPC
RNAC: 100..700ms; 100ms; 200ms(Range, Steps; Default)
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PC parameters at RAB setup
At the RAB setup the UL outer loop PC Controller gets the following bearer and radio link specific parameters from the Admission Control :
Radio link specific parameters Initial SIR Target Minimum value of the SIR Target Maximum value of the SIR Target
Bearer specific parameters for each DCH Initial planned Eb/No target Target BLER (Block Error Ratio) Interleaving time
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UL Quality deterioration• If the UL SIR target has reached the maximum and the UL SIR Target modification
commands, received by the outer loop PC controller from the current active PC Entity during ULQualDetRepThreshold seconds are all greater than zero, then the UL outer loop PC controller shall send the quality deterioration report to HC.
time
Target SIR
Max SIR target
Min SIR target
Actual SIR target
Quality deterioration report to HC
Quality deterioration report (if the condition is still satisfied
the message is periodically repeated)
ULQualDetRepThreshold
EnableULQualDetRepQuality deterioration report from
UL OLPC controller
RNMOBI: 0 (No) / 1 (Yes)(Steps; Default)
ULQualDetRepThresholdUL quality deterioration reporting threshold
RNMOBI : 0.5..5 s; 0.5s; 0.5s(Range; Steps; Default)
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DL Outer Loop PC
• This function is implemented in the UE in order to set the SIR target on each CCTrCH used for the DL closed loop PC.
• This SIR value is adjusted according to an autonomous function of the UE in order to achieve the same measured quality as the quality target set by the RNC.
• In order to control the DL outer loop PC quality target in UE, Admission Control (AC) determines the value of the DL BLER target for each DCH mapped on a DPCH.
• After AC functionality has determined the DL BLER target for each transport channel, the RNC sends these values to the UE.
• DL outer loop PC during the compressed mode (CM)• Different SIR targets are used during & after compressed frames
• CM parameters provided by admission control are communicated to UE by RNC
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Power Control
• Open Loop Power Control
• Fast Closed Loop Power Control
• Outer Loop Power Control
• Optional: DL Power balancing
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DL power control during SHO
• The transmit power of the added radio link is set at a calculated initial power
• based on CPICH Ec/No of the new RL from UE
• Power imbalance exists already at the beginning of the SHO
• theoretically equal to the Addition window after Event 1A
Initial Imbalance
• During SHO the DL power of the AS radio links should be at equal level (balanced) to achieve optimum interference performance
• Practical limitations cause imbalance between the RL powers• Initial imbalance• Power drifting
• Power balancing algorithm compensates the imbalance
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Power drifting
• In case of the SHO, the single power control command from the UE is detected by each WCDMA BTS independently
• Due to detection errors the PC commands are decoded differently at different WCDMA BTS• DL transmission powers of radio link on the different WCDMA BTS start drifting apart i.e. the
powers are unbalanced
UE
PC command
PC command
Detection ofPCcommand
Adjustment of DL power
Detection ofPCcommand
Adjustment of DL power
4
BTS 1BTS 2
Cell2
Actual Power P(k) Diff Power
Power
Time
Cell1
M isinterpretion Cell1 power goes – 1dB wrong
Power drifting
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Power Balancing• Power imbalance causes inefficient DL
power usage and capacity loss
• Power imbalance is eliminated by Power Balancing
• Power balancing algorithm is controlled by RNC
• BTS calculates power corrections used in DL fast closed loop power control
• Power Balancing can be activated with PowerBalancing; it is always used for SHO links
• Power Balancing ends automatically when• The SHO state ends• The dedicated measurement report does not
arrive from a SHO branch before timeout• Timeout is defined to be 10 times the largest
Reporting Period of all involved radio links
I ub
SRNC
BS #2
I ub
DRNC
BS #3
I ur
from BS's to RNC: Averaged DL power from RNC to BS's: Initial parameters, reference transmission power
L3
L3
L3
BS #1
DL fast closed loop PC / PB algorithm
DL fast closed loop PC / PB algorithm
DL fast closed loop PC / PB algorithm
HC/PBInit parameters+ Pref update
PowerBalancing RNFC; not in use (0), in use (1)
• The dedicated measurement fails for any active set branch• When the last RL of the serving RNC is deleted in anchoring situation
• Power balancing is not supported in anchoring, so it is deactivated • Power Balancing can be activated again if the anchoring situation ends
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Power Balancing – RNC
• RNC calculates DL RL power reference value & send it to all BTSs involved in SHO• Reference power is sent in NBAP: DL POWER CONTROL REQUEST message
• Reference power only if change in value than value of parameter MinPrefChange
• 1st algorithm gives initial reference power, when Power Balancing is started up• The initial DL transmission powers of all radio links participating in the SHO are calculated and
the largest value is selected as Phighest
Initial reference power: Pref_ini = Phighest – PrefSubtract
• 2nd algorithm gives the updated reference power, when Power Balancing & related measurements already running
• RNC calculates reference value based on received DL RL power measurements PDLaverage
• Reference power can be updated after receiving the NBAP: DEDICATED MEASUREMENT REPORT from each SHO branch
• Highest AS BTS measurement value PDLaverage(s) is used for reference power calculation
Updated reference power: Pref = PDLaverage(s) – PP-CPICH(s) – PrefSubtract
PrefSubtractRNAC; 0..10; 1; 2 dB
MinPrefChange new Ref. Power to WBTS
only if change RNAC; 1..6; 1; 3 dB
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Power Balancing – BTS
• Power balancing algorithm works in the WCDMA BTS together with the DL fast closed loop PC when the SHO is on
• The DL power at time instant k: P(k) = P(k-1) + PTPC(k) + Pbal(k)
AdjustmentPeriod
Cell2
Actual Power Imbalance
Power
Time
Reference power calculated by RNC Adjustment period starts
Cell1
AdjustmentPeriod
Power correctionsAdjustmentPeriod
RNAC; 1..256; 1; 2 framesperiod until DL Tx pwr has to be
corrected to Ref pwr
MaxAdjustmentStep RNAC; 1..10; 1; 8 slots
max. adjustment = 1 dB
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• Power correction is calculated in the BTS so that the total change over the adjustment period AdjustmentPeriod equals
Pbal = (1 – r)(Pref + PP-CPICH(s) – Pinit)
Where
• Pinit is the code power of the last slot of the previous adjustment period
• r is the AdjustmentRatio
• Maximum adjustment is limited to 1 dB within MaxAdjustmentStep (time slots)
• During which the accumulated power adjustment will be no more than 1dB
Initial in-balance at the beginning of the adjustment period
AdjustmentPeriod RNAC; 1..256; 1; 2 frames
r = AdjustmentRatio RNAC; 1..100%; 1%; 0%
Power corrected to DL reference power
MaxAdjustmentStep RNAC; 1..10; 1; 8 slots
max. adjustment = 1 dB
Power Balancing – BTS
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Power Balancing – Example
RNC
BTS1 BTS2
20 dBm 25 dBm
RNC
BTS1 BTS2
Pref = 25 dBm – 33 dBm – 2 dB = -10 dB
RNC
BTS1 BTS2
-10 dB -10 dB
RNC
BTS1 BTS2
23 dBm* 23 dBm*
1 2
3 4
Initial imbalance = -2 dBInitial imbalance = 3 dB
AdjustmentPeriod
* UE closer to BTS1 , power drivenby fast closed loop PC
Pref = PDLaverage(s) – PP-CPICH(s) – PrefSubstract
Pref = 25 dBm – 33 dBm - 2 dB = -10 dB
Pbal = (1-r) (Pref + PP-CPICH(s) – Pinit)
= (1 – 0) (-10 + 33 – 20) = 3 dB
Pbal = (1 – 0) (-10 + 33 – 25) = -2 dB