cdma2000 1x power control algorithm
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Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
英文标题 :40-47pt
副标题 :26-30pt
字体颜色 : 反白内部使用字体 :
FrutigerNext LT Medium
外部使用字体 : Arial
中文标题 :35-47pt
字体 : 黑体 副标题 :24-28pt
字体颜色 : 反白字体 : 细黑体
cdma2000 1X Power Control Algorithm
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Objectives
Upon completion of this course, you will be able to:
State the significance of power control in CDMA
Analyze reverse power control algorithm
Analyze forward power control algorithm
Optimize power control parameter
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Contents
1. Purpose and Principle
2. Classification and Application
3. Reverse Power Control Algorithm
4. Forward Power Control Algorithm
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Contents
1. Purpose and Principle
2. Classification and Application
3. Reverse Power Control
4. Forward Power Control
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Purpose & Principle
Purpose
Overcome far and near effect
Reduce the interference, increase the system capacity
Basic principle
Control the transmitting power of BTS and MS. Ensure the
power at receiver through complicated wireless
propagation environment can meet the required
demodulation threshold.
Based on the previous point, decrease the power of MS
and BTS as much as possible, to decrease the interference
among the user, make the network performance best.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Contents
1. Purpose and Principle
2. Classification and Application
3. Reverse Power Control Algorithm
4. Forward Power Control Algorithm
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Classification
According to the direction, power control is divided:
Reverse power control
Forward power control
According to the function, power control is divided:
Reverse power control
Reverse open loop power control
Reverse closed loop power control (Inner loop + Outer loop)
Forward power control
Measurement report power control
EIB power control
Fast power control (Inner loop + Outer loop)
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Application
Forward power control base on the protocol revision:
The revision of MS is 2-5 and RC1 channel is allocated,
measurement report power control has high priority.
The revision of MS is 3-5 and RC2 channel is allocated,
EIB power control is preferred.
The revision of MS is above 6 (including 6), forward
fast power control is preferred.
Reverse power control:
All the version of MS adopts the reverse power control
algorithm, including open loop and closed loop.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Contents
1. Purpose and Principle
2. Classification and Application
3. Reverse Power Control Algorithm
4. Forward Power Control Algorithm
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Contents
3. Reverse Power Control Algorithm
3.1 Introduction
3.2 Open Loop Power Control
3.3 Closed Loop Power Control
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
The object of reverse power control is MS The purpose of reverse power control:
Overcome the far and near effect Ensure the power at BTS receiver meet the minimum requi
red Eb/Nt , decrease the interference and increase the syste
m capacity
Reverse Power Control
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Power Control in Access Process
Reverse open loop power control starts
Reverse closed loop power control starts
BTS
Channel Assnmt . Msg .
Origination Msg
Base Sta . Acknlgmt . Order
TFC frames of 000s
TFC preamble of 000s
Base Sta . Acknlgmt . Order
Mobile Sta . Ackngmt . Order
Service Connect Msg .
Svc . Connect Complete Msg
Base Sta . Acknlgmt . Order
The first access probe
PAGING
FW TFC
PAGING
RV TFC
FW FC
RV TFC
FW TFC
RV TFC
FW TFC
A successful access attempt
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Contents
3. Reverse Power Control
3.1 Introduction
3.2 Open Loop Power Control
3.3 Closed Loop Power Control
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Received Powertransmitting
power
Supposing that the property on both link are the same Estimate the transmitting power according to the total r
eceived power The factor to influence on transmitting power of MS:
Circumstance of the channel Path loss Cell Load
Principle
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Code Parameter Unit Remark
AMean _receive
_powerdBm Total received power
B Offset _ power dBRelated to RC, band class, and channel
type
C NOM _ PWR dB Getting from APM
D NOM _ PWR _ EXT dB Getting from APM
E INIT_PWR dB Getting from APM
n ntime
sAccess probe sequence
G PWR_STEP dB Getting from APM
Transmitting power (dBm)= -A + B + C - 16×D + E + F F is access _ probe _ correction, the value shall be calcul
ated by Access _ probe _ correction = (n-1)×G
Access Channel (IS95A)
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Code Parameter Unit Remark
AMean _receive
_powerdBm Total received power
B Offset _ power dB Related to RC, band class, and channel type
C NOM _ PWR dB Getting from APM
D NOM _ PWR _ EXT dB Getting from APM
E INIT_PWR dB Getting from APM
n ntime
sAccess probe sequence
G PWR_STEP dB Getting from APM
HInterference _
correctiondB
Interference _ correction =min { max (
-7-Ec/Io ,0 ) ,7 }
Transmitting power (dBm) = -A + B + C -16×D+ E + F + H
F is access _ probe _ correction, the value shall been calc
ulated by Access _ probe _ correction = (n-1) × G
Access Channel (IS95B, IS2000)
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Traffic Channel (RC1, RC2)
Transmitting power (dBm) = -A+ B+ C- 16×D+ E+ F+ H+ J
F is access _ probe _ correction, the value shall been calc
ulated by Access _ probe _ correction = (n-1)×G
Code Parameter Unit Remark
A Mean_receive _power dBm Total received power
B, C, D,
E, G, HMixed Parameter dB
The meaning of each
parameter
is the same as previous slide
n n times Access probe sequence
J RLGAIN_ADJ dB Getting from ECAM
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Traffic Channel (RC3, RC4) Transmitting power of R-PICH= -A+ B+ C- 16×D+ E+ F+ H+ J
F is access _ probe _ correction, the value shall been calculated
by Access _ probe _ correction = (n-1)×G
Transmitting power of R-FCH= Transmitting power of R-PICH+
KCode Parameter Unit Remark
A Mean_receive _power dBm Total received power
B, C, D,
E, G, HMixed Parameter dB
The meaning of each
parameter
is the same as previous slide
n n times Access probe sequence
J RLGAIN_ADJ dB Getting from ECAM
KRLGAIN_TRAFFIC_PIL
OT dB Getting from ESPM
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Open Loop Parameters
Parameter RangeDefault
SettingUnit
NOM_PWR -8~7 4 dB
NOM _ PWR _ EXT Y/ N NY: Sent
N: Not sent
NUMSTEP 0~15 5 Times
INIT_PWR -16~15 0 dB
PWR_STEP 0~7 4 dB
Command: MOD APM
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Review Reverse open loop power control is simple and direct,
and it doesn't need to exchange the control information
between the BTS and MS, saving the overload message.
Reverse open loop power control estimate the power
base on forward link measurement, but precision is too
low.
Forward link and reverse link are not correlative
The total received power is subject to the influence on
neighbor cell, and the error is remarkable when the user is
on the border of cell
Response frequency is around 50 Hz.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Contents
3. Reverse Power Control Algorithm
3.1 Introduction
3.2 Open Loop Power Control
3.3 Closed Loop Power Control
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Principle
Reverse close loop power control adjust the power of MS base on the R-FER and Eb/Nt, it consists of inner and outer loop
Out loop PC change the setting Eb/Nt on the reverse link periodically
Inner loop PC adjust the power of MS base on the setting Eb/Nt
Inner Loop Power ControlOuter Loop Power Control
Insert power control bit Set Eb/Nt value
Detect reverse Eb/Nt Calculate FER
Power control bit
20ms forward traffic frame
1.25ms
… …
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Demodulate R-TCH to get measurement Eb/Nt
Power Control Bit = 1
Forward PC sub-channel
Setting Eb/Nt of BTS (variable)
Adjust the R-TCH power
of MS
-+
Result ≤ 0 ?YES NO
Power Control Bit = 0
Inner Loop Power Control Flow
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Demodulate R-TCH to get the measurement FER
Target FER in BSC
Setting Eb/Nt of BTS (varia
ble)
- +
Increase Eb/Nt
Send it on Abis link
Result ≤ 0 ?YES NO
Decrease Eb/Nt
Outer Loop Power Control Flow
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Target FER Configuration
Parameter Range Default Value Unit
F-FCH Voice Service
Expected FER10.2%~30% 1% 1%
R-FCH Voice Service
Expected FER10.2%~30% 1% 1%
F-FCH Data Service
Expected FER10.2%~30% 1% 1%
R-FCH Data Service
Expected FER10.2%~30% 1% 1%
F- nXSCH Data Service Exp
ected FER10.2%~30% Log2
n × 1% 1%
R- nXSCH Data Service Exp
ected FER10.2%~30% Log2
n × 1% 1%
Command: MOD FER
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Parameters Parameters
Parameters RangeDefault
ValueUnit
Outer _ Loop _ Power _ Algorithm _
Factor0~100 0 %
Eb/Nt _ Down _ Step 0~255 1 0.125dB
Eb/Nt _ Max. _ Adjustment _ Step 0~255 10 0.125dB
Reverse _ Initial _ Set _ Value 0~255 48 0.125dB
Max. _ Value _ of _ FCH _ Outer _ Loop 0~255 96 0.125dB
Min. _ Value _ of _ FCH _ Outer _ Loop 0~255 16 0.125dB
Reverse _ Power _ Step 0.25~1 0.50.25 /0.5
/1dB
Reverse_Gain_Adjust -8~7 3 dB
Min. _ Value _ of _ SCH 0~255 32 0.125dB
Max. _ Value _ of _ SCH 0~255 96 0.125dB
Command: MOD RCLPC
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Adjustment Process
Reverse _ Outer _ Loop _ Power _ Control _ Period
Eb/Nt _ Down _ Step
Eb/Nt _ Up _ Step
Eb/Nt
frame0 33 66 99 132 165 198
Max. _ Value _ of _ FCH _ Outer _ Loop
Min. _ Value _ of _ FCH _ Outer _ Loop
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Reverse PC in Soft Handoff
Base on the understanding of purpose and principle
of power control, how to analyze the following power
control?
11
0
Finally, it would increase or decrease ??
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
In the current system, reverse power control is realized
by open loop and closed loop power control together. MS starts the reverse open loop power control with the first
access probe
MS starts the reverse closed loop power control after
successfully demodulate the first reverse traffic channel
preamble, to correct the precision of reverse open loop power
control
Compared with forward power control, reverse power
control is more complicated. With large variance range
and high sensitivity, reverse power control compensate
fast fading.
Summary
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Contents
1. Purpose and Principle
2. Classification and Application
3. Reverse Power Control Algorithm
4. Forward Power Control Algorithm
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Contents
4. Forward Power Control Algorithm
4.1 Introduction
4.2 Measurement Report Power Control
4.3 EIB Power Control
4.4 Fast Power Control
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Purpose
The object of forward power control is BTS The purpose of forward power control:
To maximize forward system capacity, it decreases the power of forward traffic channel as much as possible, on the condition that ensure the power at the receiver with the minimum required Eb/Nt
To improve the quality of service on the border of cell, and decrease the interference to the neighbor cell as much as possible
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Contents
4. Forward Power Control Algorithm
4.1 Introduction
4.2 Measurement Report Power Control
4.3 EIB Power Control
4.4 Fast Power Control
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Classification
MS measure forward traffic frame, and report the
PMRM to BSC, then the BSC adjust forward channel
gain depending on that PMRM, the frame processing
board sends it in forward traffic frame to the BTS
The measurement report power control includes:
Threshold mode: report PMRM to the BTS, only when
the number of bad frame meet the threshold defined in
a period
Period mode: report PMRM to BTS every other a period
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Current FERReport PMRM
Target FER in BSC
MS measures the forward traffic frame
-+
Increase
Forward Channel Gain
Result ≤ 0 ?
Decrease
YES NO
Adjust the F-TCH power of
BTS
Period Mode
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Report PMRM
BSC measures PMRM periodically
MS measures the forward traffic frame periodically
Forward Channel Gain
Bad frame NO.≤T?
Decrease
YES
NO
Adjust the F-TCH
power of BTS
Increase
PMRM No PMRM
Threshold Mode
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Parameters
Parameter RangeDefault
settingUnit
Max. TCH power relative to
pilot
-
200~5
5
0 0.25dB
Min. TCH power relative to
pilot
-
200~5
5
-36 0.25dB
Initial TCH power relative to
pilot
-
200~5
5
0 0.25dB
Power Decrease Step 0~255 2 0.25dB
Reporting Threshold 0~31 2 frame
Reporting Frame Count 5~905 113 frame
Power Report Delay 0~31 1 4 frames
Command: MOD FSLOWPC
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Contents
4. Forward Power Control
4.1 Introduction
4.2 Measurement report Power Control
4.3 EIB Power Control
4.4 Fast Power Control
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Principle
In IS95B system, specially for rate set 2, BSC adjusts the
forward channel gain according to EIB which is carried in
reverse traffic frame
EIB = 0, it means good frame in forward channel
EIB = 1, it means bad frame in forward channel
Rate set 2 in IS95 system adopts 13K QCELP, the system
control the power of BTS according to the EIB in each
frame, no need PMRM message, so it can do the power
control faster, the power control frequency is 50 Hz
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Principle (Cont.)
EIB is fixed in the first bit of each reverse traffic frame.
It takes two frames delay to process the EIB.
i-2 i-1 i i+1
i+2 i+1 i i-1
Frame format of Rate Set 2 :1 frame = 288 bits (20ms)
287 bits0/1
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
ParametersParameters
Parameters Range Default setting Unit
Max. TCH power relative to pilot
-
200~5
5
-40 0.25dB
Min. TCH power relative to pilot
-
200~5
5
-64 0.25dB
Bad Frame Number 0~255 3 frame
Power Up Step 0~255 8 0.25dB
Power Down Small Step 0~255 1 0.25dB
Power Down Big Step 0~255 2 0.25dB
Command: MOD FEIBPC
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Adjustment ProcessGain ( dB )
Frame0 1 2 3 4 5 6 7 8 9 10 11
Power Down Small Step
Max Transmitting Power
Power Down Big Step
Power Up Step
Min Transmitting Power
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Contents
4. Forward Power Control Algorithm
4.1 Introduction
4.2 Measurement report Power Control
4.3 EIB Power Control
4.4 Fast Power Control
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Principle
Pilot Power Control
1 Power Control Group=1536 PN Chips
384 Chips
1.25 ms
Forward power control contains inner loop and outer loop power control, and the inner loop and outer power control work together
Insert power control bit Set target Eb/Nt value
Detect forward Eb/Nt Calculate FER
Inner LoopOuter Loop
Target FER get from ECAM
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Fast Power Control Mode
When the protocol revision of MS is 6, it supports some ty
pes of forward fast power control mode (FPC_MODE):
FPC_MODE= 000: one power control sub-channel , 800 Hz FPC_MODE= 001: two power control sub-channels, 400-400 Hz FPC_MODE= 010: two power control sub-channels, 200-600 Hz
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Inner Loop Power Control
Demodulate F-TCH to get measurement Eb/Nt
Power Control Bit = 1
Reverse PC sub-channel
Setting Eb/Nt of MS (variable)
Adjust the F-TCH power
of BTS
-+
Result ≤ 0 ?
Power Control Bit = 0
YES NO
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Outer Loop Power Control
Demodulate R-TCH to get measurement FER
Target FER carried by F-PCH
Setting Eb/Nt
(variable) Last Eb/Nt
MS inside
Chip will complete automatically depending on some algorithm
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Important Parameter
Channel Parameter Range Default
SettingUnit
Voice/Data FCH
Initial Eb/Nt 0~255 40 0.125dB
Min Eb/Nt 0~255 16 0.125dB
Max Eb/Nt 0~255 80 0.125dB
1X SCH ~ (32X SCH)
Initial Eb/Nt (Relative to FCH) 0~255 -16 (1X) 0.25dB
Min Eb/Nt 0~255 -52 (1X) 0.25dB
Max Eb/Nt 0~255 -16 (1X) 0.25dB
FCH /SCH Forward Power Control Step 1-4 2 0.25dB
Voice/Data FCH Initial Power Correction
Value0~255 46 0.25dB
Command: MOD FFASTPC
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Important Parameters (Cont.)
Channel Parameter Range Default Setting Unit
IS95/ IS2000
Forward Power
Control Sub-
channel
Gain 1 0~127
/
0~31
0/ 12 0.25dB
Gain 2 12/ 24 0.25dB
Gain 3 19/ 31 0.25dB
Voice/Data FCH
Channel Min. Gain 1 -255~0 -96 0.25dB
Channel Min. Gain 2 -255~0 -84 0.25dB
Channel Min. Gain 3 -255~0 -72 0.25dB
Channel Max. Gain 1 -255~0 0 0.25dB
Channel Max. Gain 2 -255~0 0 0.25dB
Channel Max. Gain 3 -255~0 0 0.25dB
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Forward Fast PC in Soft Handoff In soft handoff, forward branches are combined in MS, and th
e quality of service is guaranteed as long as one branch is good. So the power of the other forward branch shall be waste to the whole system
In soft handoff, MS combines branches based on the maximum ratio algorithm. If the At/Ap of different branches is not balanced, the At won't be combined fully, and the combination gain in forward will be decreased, so it may occur error coding, and need BTS to increase forward power to meet the target FER, it will result in system capacity loss
Maximum ratio (At/Ap)
= power of traffic channel/ power of pilot channel
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Power Synchronization
In order to balance the At/Ap among forward soft handoff
branches, save the forward power effectively, and increase the usage of forward resource, Huawei company designes the power synchronization algorithm.
Receive set
Correlator 1
Correlator 2
Correlator 3
Searcher correlator
0°
90°
Combine the branches which have close At/Ap
At/ Ap
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Power Synchronization
Principle Make the power of the branch with worse quality close to th
at of the branch with good quality as much as possible, because the power of the branch with good quality must be lower, and in order to get a high combination gain, the At/ Ap of soft handoff branches should be close.
SynchronizationAlgorithm
Reverse traffic frame
Forward traffic frame
BTSBSC
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
RC1 and RC2 in CDMA 1X system adopt forward power control as same as IS-95 system, RC3~RC5 adopt forward fast power control ;
Forward fast power control contains inner loop and outer loop power control, and in the current system, inner loop and outer loop cooperate to control the power of forward traffic channel of the BTS.
Summary
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