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Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
WCDMA Power Control and Relevant Parameters
Page3Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Objectives
Upon completion of this course, you will be able to:
Describe the purpose and function of power control
Explain open loop power control and parameters
Explain inner loop power control and relevant
parameters
Explain outer loop power control and relevant
parameters
Page4Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Contents
1. Power Control Overview
2. Open Loop Power Control
3. Closed Loop Power Control
Page5Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Purpose of Uplink Power Control
Uplink Transmission Character Self-interference system
Uplink capacity is limited by interference level
Near-far effect
Fading
Uplink Power Control Function Ensure uplink quality with minimum transmission power
Decrease interference to other UE, and increase capacity
Solve the near-far effect
Save UE transmission power
Page6Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Purpose of Downlink Power Control
Downlink Transmission Character Interference among different subscribers
Interference from other adjacent cells
Downlink capacity is limited by NodeB transmission power
Fading
Downlink Power Control Function Ensure downlink quality with minimum transmission power
Decrease interference to other cells, and increase capacity
Save NodeB transmission power
Page7Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Effect of Power Control
Time (ms)0 200 400 600 800
-20
-15
-10
-5
0
5
10
15
20R
elat
ive
po
wer
(d
B)
Channel Fading
Transmitting power
Receiving power
Page8Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Power Control Classification
Open Loop Power Control
Uplink / Downlink Open Loop Power Control
Closed Loop Power Control
Uplink / Downlink Inner Loop Power Control
Uplink / Downlink Outer Loop Power Control
Page9Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Power Control For Physical Channels
Power control methods are adopted for these physical channels:
“√" – can be applied, “×" – not applied
Physical
Channel
Open Loop
Power Control
Closed Loop Power ControlNo
Power Control
Inner Loop Power Control
Outer Loop Power Control
DPDCH √ √ √ ×
DPCCH √ √ √ × SCH × × × √
PCCPCH × × × √
SCCPCH × × × √
PRACH √ × × ×
AICH × × × √
PICH × × × √
Page10Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Common Physical Channel Power Parameters
MAXTXPOWER
Parameter name: Max transmit power of cell
The recommended value is 430, namely 43dBm
PCPICHPOWER
Parameter name: PCPICH transmit power
The recommended value is 330, namely 33dBm
Page11Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Common Physical Channel Power Parameters
PSCHPOWER or SSCHPOWER
Parameter name: PSCH / SCCH transmit power
The recommended value is -50, namely -5dB
BCHPOWER
Parameter name: BCH transmit power
The recommended value is -20, namely -2dB
Page12Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Common Physical Channel Power Parameters
MAXFACHPOWER
Parameter name: Max transmit power of FACH
The recommended value is 10, namely 1dB
PCHPOWER
Parameter name: PCH transmit power
The recommended value is -20, namely -2dB
Page13Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Common Physical Channel Power Parameters
AICHPOWEROFFSET
Parameter name: AICH power offset
The default value of this parameter is -6, namely -6dB
PICHPOWEROFFSET
Parameter name: PICH power offset
The default value of this parameter is -7, namely -7dB
Page14Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Contents
1. Power Control Overview
2. Open Loop Power Control
3. Closed Loop Power Control
Page15Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Contents
2. Open Loop Power Control
2.1 Open Loop Power Control Overview
2.2 PRACH Open Loop Power Control
2.3 Downlink Dedicated Channel Open Loop Power
Control
2.4 Uplink Dedicated Channel Open Loop Power Control
Page16Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Open Loop Power Control Overview
Purpose
Calculate the initial transmission power of uplink / downlink
channels
Principle
Estimates the downlink signal power loss on propagation path
Path loss of the uplink channel is related to the downlink
channel
Application
Open loop power control is applied only at the beginning of
connection setup to set the initial power value.
Page17Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Contents
2. Open Loop Power Control
2.1 Open Loop Power Control Overview
2.2 PRACH Open Loop Power Control
2.3 Downlink Dedicated Channel Open Loop Power
Control
2.4 Uplink Dedicated Channel Open Loop Power Control
Page18Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
PRACH Open Loop Power Control
5. Downlink Synchronization
UE Node BServing
RNC
DCH - FP
Allocate RNTISelect L1 and L2parameters
RRCRRC
NBAPNBAP3. Radio Link Setup Response
NBAPNBAP2. Radio Link Setup Request
RRCRRC7. CCCH: RRC Connection Set up
Start RX description
Start TX description
4. ALCAP Iub Data Transport Bearer Setup
RRCRRC9. DCCH: RRC Connection Setup Complete
6. Uplink Synchronization
NBAPNBAP8. Radio Link Restore Indication
DCH - FP
DCH - FP
DCH - FP
Open loop power control of PRACH
1. CCCH: RRC Connection Request
Page19Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
PRACH Open Loop Power Control
Initial Power Calculation for the First Preamble
When UE needs to set up a RRC connection, the initial
power of uplink PRACH can be calculated according to
the following formula:
Power Tx Initial gCalculatin For Value Constant+ceInterferen UL+
CPICH_RSCP-Power Transmit PCPICH=ernitial_PowPreamble_I
Page20Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
PRACH Open Loop Power Control Parameters
CONSTANTVALUE
Parameter name: Constant value for calculating initial
TX power
The recommended value is -20, namely -20dB
Page21Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
PRACH Open Loop Power Control
Timing relationship of PRACH and AICH
AICH
PRACH
1 access slot
p-a
p-m p-p
Pre-amble
Pre-amble
Message part
Acq. Ind.
Page22Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
PRACH Open Loop Power Control Parameters AICHTXTIMING
Parameter name: AICH transmission timing Content:
When AICHTXTIMING = 0,
p-p,min = 15360 chips, p-a = 7680 chips, p-m = 15360 chips
When AICHTXTIMING = 1,
p-p,min = 20480 chips, p-a = 12800 chips, p-m = 20480 chips
The recommended value is 1
Page23Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
PRACH Open Loop Power Control
Power Ramping for Preamble Retransmission
Power Ramp Step
Power Offset Pp-m
Preamble_Initial_Power
Message part
Pre-amblePre-
amble……
Pre-amblePre-
amble
# 1 # 3 # N# 2
Page24Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
PRACH Open Loop Power Control Parameters
POWERRAMPSTEP
Parameter name: Power increase step
The recommended value is 2, namely 2dB
PREAMBLERETRANSMAX
Parameter name: Max preamble retransmission
The Recommended value is 20
Page25Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
PRACH Open Loop Power Control Parameters
MMAX
Parameter name: Max preamble loop
The recommended value is 8
NB01MIN / NB01MAX
Parameter name: Random back-off lower / upper limit
The recommended value: 0 for both NB01MIN /
NB01MAX
Page26Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
PRACH Open Loop Power Control Parameters
POWEROFFSETPPM
Parameter name: Power offset
The default value:
-3dB for signalling transmission;
-2dB for service transmission.
Page27Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Contents
2. Open Loop Power Control
2.1 Open Loop Power Control Overview
2.2 PRACH Open Loop Power Control
2.3 Downlink Dedicated Channel Open Loop Power
Control
2.4 Uplink Dedicated Channel Open Loop Power Control
Page28Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
DL DPDCH Open Loop Power Control
5. Downlink Synchronization
UE Node BServing
RNC
DCH - FP
Allocate RNTISelect L1 and L2parameters
RRCRRC
NBAPNBAP3. Radio Link Setup Response
NBAPNBAP2. Radio Link Setup Request
RRCRRC7. CCCH: RRC Connection Set up
Start RX description
Start TX description
4. ALCAP Iub Data Transport Bearer Setup
RRCRRC9. DCCH: RRC Connection Setup Complete
6. Uplink Synchronization
NBAPNBAP8. Radio Link Restore Indication
DCH - FP
DCH - FP
DCH - FP
1. CCCH: RRC Connection Request
DL DPDCH Open Loop Power Control
Page29Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
DL DPDCH Open Loop Power Control
When a dedicated channel is set up, the initial power
of downlink DPDCH can be calculated according to
the following formula:
Total
CPICH
CPICHDLInitial P
)No/Ec(
P)
No
Eb(
W
RP
Page30Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
DL DPDCH Open Loop Power Control
Data1 TPC TFCI Data2 Pilot
DownlinkTransmit
Power
DPCCHDPDCH DPDCH DPCCH
PO2PO1
PO3
1 timeslot
Page31Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Downlink Power Control Restriction
The power of downlink dedicated channel is limited by
an upper and lower limit for each radio link.
The DL DPDCH power could not exceed
Maximum_DL_Power, nor could it be below
Minimum_DL_Power.
RLMAXDLPWR / RLMINDLPWR
Parameter name: RL Max / Min DL TX power
The recommended value is shown in the following table.
Page32Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Downlink Power Restriction Parameters Referential configurations for typical services:
ServiceRL Max Downlink
Transmit Power (dB)
RL Min Downlink
Transmit Power (dB)
Downlink SF
CS Domain
12.2 kbps AMR -3 -18 128
28 kbps -2 -17 64
32 kbps -2 -17 64
56 kbps 0 -15 32
64 kbps 0 -15 32
PS Domain
8 kbps -8 -23 128
32 kbps -4 -19 64
64 kbps -2 -17 32
144 kbps 0 -15 16
256 kbps 2 -13 8
384 kbps 4 -11 8
Page33Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Contents
2. Open Loop Power Control
2.1 Open Loop Power Control Overview
2.2 PRACH Open Loop Power Control
2.3 Downlink Dedicated Channel Open Loop Power
Control
2.4 Uplink Dedicated Channel Open Loop Power
Control
Page34Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
UL DPCCH Open Loop Power Control
5. Downlink Synchronization
UE Node BServing
RNC
DCH - FP
Allocate RNTISelect L1 and L2parameters
RRCRRC
NBAPNBAP3. Radio Link Setup Response
NBAPNBAP2. Radio Link Setup Request
RRCRRC7. CCCH: RRC Connection Set up
Start RX description
Start TX description
4. ALCAP Iub Data Transport Bearer Setup
RRCRRC9. DCCH: RRC Connection Setup Complete
6. Uplink Synchronization
NBAPNBAP8. Radio Link Restore Indication
DCH - FP
DCH - FP
DCH - FP
1. CCCH: RRC Connection Request
Open Loop Power Control of UL DPCCH
Page35Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
UL DPCCH Open Loop Power Control
The initial power of the uplink DPCCH can be calculated according to the following formula:
Where CPICH_RSCP means the received signal code power, the
received power measured on the CPICH.
DPCCH_Power_Offset is provided by RNC to the UE via RRC signaling.
RSCP_CPICHOffset_Power_DPCCHPower_Initial_DPCCH
Page36Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
UL DPCCH Open Loop Power Control Parameter
DEFAULTCONSTANTVALUE
Parameter name: Constant value configured by default The recommended value is -22, namely -22dB.
Page37Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Uplink Power Control Restriction
During the operation of uplink power control, the UE
transmit power shall not exceed the Maximum
Allowed Uplink Transmit Power.
MAXALLOWEDULTXPOWER Parameter name: Max allowed UE UL TX power The recommended value is 24, namely 24 dBm.
Page38Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Uplink Power Control Restriction
In addition, there are four parameters which correspond to the
maximum allowed transmit power of four classes of services
respectively:
MAXULTXPOWERFORCONV
Parameter name: Max UL TX power of Conversational service
MAXULTXPOWERFORSTR
Parameter name: Max UL TX power of Streaming service
MAXULTXPOWERFORINT
Parameter name: Max UL TX power of Interactive service
MAXULTXPOWERFORBAC
Parameter name: Max UL TX power of Background service
The recommended value is 24, namely 24 dBm.
Page39Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Contents
1. Power Control Overview
2. Open Loop Power Control
3. Closed Loop Power Control
Page40Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Contents
3. Closed Loop Power Control
3.1 Closed Loop Power Control Overview
3.2 Uplink Inner Loop Power Control
3.3 Downlink Inner Loop Power Control
3.4 Outer Loop Power Control
Page41Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Closed Loop Power Control Overview Why closed loop power control is needed?
Open loop power control is not accurate enough, it can only estimate the initial transmission power.
Closed loop power control can guarantee the QoS with minimum power. By decreasing the interference, the system capacity will be increased.
Inner LoopOuter Loop
SIRtar
SIRmea>SIRtar→ TPC=0
SIRmea<SIRtar→ TPC=1
UntilSIRmea=SIRtar
TPCBLERtar
BLERmea>BLERtar→SIRtar
BLERmea<BLERtar→SIRtar
Until BLERmea=BLERtar
TPC=1 Power
TPC=0 Power
Page42Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Contents
3. Closed Loop Power Control
3.1 Closed Loop Power Control Overview
3.2 Uplink Inner Loop Power Control
3.3 Downlink Inner Loop Power Control
3.4 Outer Loop Power Control
Page43Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Uplink Inner Loop Power Control
NodeB compares the measured SIR to the preset target SIR,
then derives TPC and sends the TPC Decision to UE.
TPC Decision( 0, 1 )
Generate TPC_cmd( -1, 0, 1 )
Adjust DPCCH Tx△DPCCH = TPC×TPC_cmd△
Single RL / Soft HOPCA1 / PCA2
Adjust DPDCH Tx( c , d )
NodeB UETransmit TPC
Inner Loop
Set SIRtar
Compare SIRmea with SIRtarSIRmea SIRtar → TPC = 0SIRmea SIRtar → TPC = 1
Page44Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Uplink Inner Loop PCA1 with Single Radio Link
For single radio link and PCA1, UE derives one TPC_cmd in
each time slot as follows:
0110110110…… ……
…… ……TPC_cmd
TPC
-111-111-111-1
This control is performed in each time slot, so the power control frequency is 1500Hz
Page45Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Uplink Inner Loop PCA2 with Single Radio Link
For single radio link and PCA2, UE derives one TPC_cmd in
each 5-slot group as follows:
This control is performed in each 5-slot group, so the power control frequency is 300Hz
110111111100000
TS14TS13TS12TS11TS10TS9TS8TS7TS6TS5TS4TS3TS2TS1TS0
10ms radio frame
Group 2Group 1 Group 3
…… ……
0000010000-10000
TPC
TPC_cmd
…… ……
Page46Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Uplink Inner Loop with Soft Handover When UE enters soft handover state, on the NodeB
side, there are two phases :
Uplink synchronization phase
Multi-radio link phase
On UE side, UE will receive different TPCs from
different RLS in one time slot. Therefore, the UE
should combine all the TPCs to get a unique
TPC_CMD.
Page47Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Uplink Inner Loop PCA1 with Soft Handover
For each slot, combine TPC from the same RLS, then get Wi
CELL1 CELL2
CELL4CELL3
RL1-1 RL1-2
RLS1
RLS2 RLS3Get TPC_cmd based on
TPC_cmd = (W1, W2, … WN)
0110110110…… ……RLS1-TPC (W1)
…… ……RLS2-TPC (W2) 1010101101
…… ……
…… ……TPC_cmd
1101100100
-1-1-1-11-1-11-1-1
RLS3-TPC (W3)
Page48Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Uplink Inner Loop PCA2 with Soft Handover
Combine TPC from same RLS
in each time slot
Calculate TPC_cmd If any TPC_tempi = -1, TPC_cmd = -1
If , TPC_cmd = 1
Otherwise, TPC_cmd = 0
Calculate TPC_tempi for each RLSi
5.0_1
1
N
iitempTPC
N
CELL1 CELL2
CELL4CELL3
RL1-1 RL1-2RLS1
RLS2 RLS3
Page49Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Uplink Inner Loop PCA2 with Soft Handover
RLS3
RLS2
RLS1 100100000000100
100110000011111
111110000011111
TS14TS13TS12TS11TS10TS9TS8TS7TS6TS5TS4TS3TS2TS1TS0
…… ……
10ms/frame
Group 1 Group 2 Group 3
RLS3
RLS2
RLS1 00000-1000000000
00000-1000010000
10000-1000010000
TS14TS13TS12TS11TS10TS9TS8TS7TS6TS5TS4TS3TS2TS1TS0
…… ……
TPC
TPC_tempi
00000-1000010000
TS14TS13TS12TS11TS10TS9TS8TS7TS6TS5TS4TS3TS2TS1TS0
…… ……
TPC_cmd
Page50Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Uplink Inner Loop Power Control Parameters
PWRCTRLALG
Parameter name: Power control algorithm selection
The recommended value is ALGORITHM1
ULTPCSTEPSIZE
Parameter name: UL closed loop power control step
size
The recommended value is 1, namely 1dB
Page51Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Contents
3. Closed Loop Power Control
3.1 Closed Loop Power Control Overview
3.2 Uplink Inner Loop Power Control
3.3 Downlink Inner Loop Power Control
3.4 Outer Loop Power Control
Page52Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Downlink Inner Loop Power Control
UE L1 compares the measured SIR to the preset target SIR, then
derives TPC and sends the TPC Decision to NodeB.
Derive TPCest(k) ( 0, 1 )
Generate PTPC(k)
Calculate P(k)
Adjust DPCH Tx Power
DPC_MODE
NodeB
L3 Set SIRtar
Derive and transmit TPC based on DPC_MODE
Inner Loop
UE
L1 compare SIRmea with
SIRtar
Page53Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Downlink Inner Loop Power Control Mode Two DPC_MODE (Downlink Power Control Mode) could
be used: If DPC_MODE = 0, UE sends a unique TPC in each slot, UTRAN
shall derive TPCest to be 0 or 1, and update the power every slot;
If DPC_MODE = 1, UE repeats the same TPC over 3 slots, UTRAN shall derive TPCest over three slots to be 0 or 1, and update the power every three slots.
Page54Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Downlink Inner Loop Power Control Parameters
DPCMODE
Parameter name: Downlink power control mode
The recommended value is SINGLE_TPC, namely
DPC_MODE = 0
Page55Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Downlink Inner Loop Power Control
After estimating the TPC, the UTRAN shall set the downlink power to P(k) for k:th slot according to the following formula:
Where P(k-1) is downlink transmission power in (k-1):th slot
PTPC(k) is the adjustment of downlink power in k:th slot
Pbal (k) is correction value according to the downlink power balance procedure. For a single radio link, Pbal (k) equals 0.
)k(P)k(P)1k(P)k(P balTPC
Page56Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Downlink Inner Loop Power Control
PTPC(k) is calculated according to the following:
If the value of “Limited Power Increase Used”
parameter is “Not Used” , then:
Where
TPCest (k) is uplink received TPC of the k:th slot
TPC is downlink power adjustment step size
0)k(TPC if
1)k(TPC if )k(P
estTPC
estTPCTPC
Page57Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Downlink Inner Loop Power Control
If the value of “Limited Power Increase Used”
parameter is “Used” , then:
Where
1k
Size_Window_Average_Power_DLkiTPCsum )i(P)k(
0)k(TPC if
Limit_Raise_Power)k( and 1)k(TPC if 0
Limit_Raise_Power)k( and 1)k(TPC if
)k(P
estTPC
TPCsumest
TPCsumestTPC
TPC
Page58Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Downlink Inner Loop Power Control Parameters
INNER_LOOP_DL_LMTED_PWR_INC_SWITCH
This is one switch in PCSWITCH (Power control
algorithm switch) parameter.
The default value is 1, namely ON.
FDDTPCDLSTEPSIZE
Parameter name: FDD DL power control step size
The recommended value is STEPSIZE_1DB, namely 1dB
Page59Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Downlink Power Balance
Purpose The purpose of this procedure is
to balance the DL transmission
powers of more than one Radio
Links.
The start and stop of DPB The power offset of two RLs is greate
r than the DPB start threshold, the DPB process is started
The power offset of two RLs is less than the DPB stop threshold, the DPB process is stopped
NodeB NodeB
Monitor the Tx power of NodeBs and start the DPB
process
DPB process
Page60Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Downlink Power Balance Parameters
DOWNLINK_POWER_BALANCE_SWITCH
This is one switch in PCSWITCH (Power control algorithm
switch) parameter.
The default value is 1, namely ON.
DPBSTARTTHD / DPBSTOPTHD
Parameter name: DPB start threshold / DPB stop threshold
The recommended value:
DPB start threshold 8, namely 4dB;
DPB stop threshold 4, namely 2dB.
Page61Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Contents
3. Closed Loop Power Control
3.1 Closed Loop Power Control Overview
3.2 Uplink Inner Loop Power Control
3.3 Downlink Inner Loop Power Control
3.4 Outer Loop Power Control
Page62Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Outer Loop Power Control
Why we need outer loop power control?
SIR
BLER
Different curves correspond to different multi-path environment
Page63Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Uplink Outer Loop Power Control
NodeB UE
Transmit TPC
Measure SIR and compare with SIRtar
Inner loop
Set SIRtar
Out loop
RNC
Measure BLER of received data and compare with the BLERtar
Set BLERtar
Page64Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Initial SIR Setting
The initial SIR target value is provided by the RNC to the NodeB through the SIR_init_target_value which is service-dependent.
For the same SRB or TRB, the values of SIR_init_target_value, Maximum_SIR_target, and Minimum_SIR_target must fulfill the following requirement: Minimum_SIR_target ≤ SIR_init_target_value ≤ Maximum_SIR_target..
Page65Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Adjusting the SIR Target
SIRtar Adjustment
Where i is the i:th transport channel. n is the n:th adjustment period.
FactorStep
BLER
BLER)1n(BLER)1n(SIRMAX)n(SIR i
i,tar
i,tari,meastartar
Page66Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
SIR Target Adjustment Limitation
The parameters MaxSirStepUp and MaxSirStepDown limit the adjustment range of the SIRtar , and the algorithm is:
If SIRtar 0 and SIRtar “MaxSirStepUp” ,
then SIRtar (n+1) = SIRtar (n) + MaxSirStepUp If SIRtar 0 and ABS(SIRtar ) “MaxSirStepDown” ,
then SIRtar (n+1) = SIRtar (n) – MaxSirStepDown
Page67Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Parameters of BLER-based outer-loop powercontrol on RAB basis
ServiceSRB 3.4k
SRB 13.6
k
AMR 12.2
k
CSD 64k
PS I/B 8k
PS I/B 16k
PS I/B 32k
PS I/B 64k
PS I/B
128k
PS I/B
144k
PS I/B
256k
PS I/B
384k
SIR init target value
102 122 102 122 102 102 102 102 102 107 122 142
OLPC adjustmen
t period4 2 2 2 4 2 2 2 2 2 2 2
Service DCH_BLER
target value
-20 -20 -20 -27 -20 -20 -20 -20 -20 -20 -20 -20
SIR adjustmen
t step4 10 5 2 4 4 4 4 4 4 4 4
MaxSirStepUp 400 500 500 1000 400 400 400 400 400 400 400 400
MaxSirStepDown 200 200 200 100 200 200 200 200 200 200 200 200
Maximum SIR target
132 132 132 152 132 132 132 132 132 137 152 172
Minimum SIR target
62 62 62 62 62 62 62 62 62 62 62 62
Page68Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Uplink Outer Loop Power Control Parameters
OLPC_SWITCH
This is one switch in PCSWITCH (Power control
algorithm switch) parameter.
The default value is 1, namely ON
Page69Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Downlink Outer Loop Power Control
NodeB
set SIRtar
Transmit TPC
Measure SIR and compare with SIRtar
Measure BLER of received data and compare with the
BLERtar
Outer loop
Inner loop
L1
L3
UE
Page70Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Summary
In this course, we have discussed function, principle
and common parameters of the following power
control algorithm:
Open loop power control
Inner loop power control
Outer loop power control
Thank youwww.huawei.com
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