RG000003 CDMA1X Introduction to Power Control ISSUE2.1(New)

7/30/2019 RG000003 CDMA1X Introduction to Power Control ISSUE2.1(New)

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HUAWEI TECHNOLOGIES CO., LTD.

www.huawei.com

HUAWEI Confidential

Security Level:

CDMA1X Power Control

Algorithm



HUAWEI TECHNOLOGIES CO., LTD. HUAWEI Confidential Page 2

One of the aims of the CDMA1X system is

to maximize the number of its users. If each

mobile station (MS) adjusts its transmitter

power to minimize the signal noise received

by the base transceiver station (BTS), the

capacity of the system is maximized. Higher

power brings higher interference and results

in more capacity loss. Power control can

adjust the transmission power of the MS and

BTS, aiming to minimize the interference.

Preface




References

IS2000a Protocols

CDMA System Engineering Manual

CDMA1X BSS Parameter Configuration Guide




Goals

After learning this course, you will learn the

following：

The importance of the power control of the CDMA

system

Categories and calculating theories of the power control

Data configuration of the power control




Chapter 1 Goals and Principles of Power Control

Chapter 2 Categories and Calculation of Power Control

Chapter 3 Data Configuration of Power Control

Contents




Goals and Principles of Power Control

CDMA Concept: cocktail lounge Each couple of customers is in a

same room.

Each couple of customers speaks a

language different from that spoken

by other couples.

If the noise becomes louder, all the

customers will raise their voices.

If the noise is too louder, the

customers may go to other rooms.

The customer who speaks too

loudly will affect the

communication of others.





Gains from the Cocktail Lounge

The ground noise in current environment must be low enough. That is, the

working frequency band of the system is not interfered.

The power control is very important in the CDMA system. The

transmission power of the MS near the BTS is relatively low and is highfor the MS far from the BTS. All the MS should transmit signals with as

low power as possible, for the transmission power of an MS is the noise

for other MS.

In the cocktail, each couple of customers speaks different language, which

is like that using different codes to distinguish users.





The transmission power of the control BTS and MS must

ensure that the signal sent to the receiver through the

complicated radio space can meet the threshold of correct

demodulation.

When the first principle is satisfied, the transmission

power of the BTS and MS is required to be lowered as much

as possible to decrease the interference between users and

best optimize the network performance.

The transmission power of the MS near the BTS is lower

than that of the MS far from the BTS and of the MS in the

fading areas.

Basic Principles




Questions

What are the goals of the power control?

What are the principles of the power control?







Contents





Section 1 Categories of Power Control

Section 2 Calculation of Reverse Power Control

Section 3 Calculation of Forward Power Control

Contents




Categories of Power Control

Based on the direction, we have:Reverse power control

Forward power control

The previous two kinds of power control are divided into the

following respectively：

Reverse power control

−Reverse open loop power control

−Reverse closed loop power control

Forward power control

−Power control based on the measurement report

−EIB power control

−Forward quick power control








Contents




Calculation of Power Control

Reverse Power Control

The reverse power control is for the MS. The major aim is to ensure that the

signals received by the BTS receiver can reach the minimize required Eb/Nt

value through the adjustment of the transmission power of the MS.

Compared with the forward power control, the requirements for the reverse

power control is higher and the process is more complicated: wide dynamic

changes, high sensitivity (to adapt to the quickly-changed environment)

Eb/Nt=bit energy/effective noise power spectral density

Ec/Io=chip energy/carrier frequency total power spectral density





Theories of Reverse Open Loop Power Control

The reverse open loop power control bases on the hypothesis that the loss of the

forward link and the reverse link is similar.

Based on this hypothesis, the MS estimates the forward link loss according to the total

received power and then estimates the transmission power of the MS.

Transmission power of the MS

Forward link loss (dB)||

Reverse link loss (dB)

Transmission power

of the BTS

Receipt power of the BTS

Demodulation of the

BTS

Reverse link loss (dB)=Transmission power of the BTS (dBm)-Receipt

power of the MS (dBm)





Theories of Reverse Open Loop Power Control

Tx_power = －MeanRx_Power + offsetpower + NOM_PWR –

16* NOM_PWR_EXTs + INIT_PWR+ interference correction

Ⅰ

Ⅲ

Ⅱ

Ⅰ ：

Ⅱ ：

Ⅲ ：

Tx_power = Ⅰ + PWR_STEP

Tx_power = Ⅱ + PWR_STEP

ACH

FCH ( 95 ) or PICH ( 2000 )

Imported to

Ⅳ

FCH ( 2000 )

Ⅳ ：

Ⅴ ：

Tx_power = Ⅲ + RLGAIN_ADJs

Tx_power = Ⅳ + RLGAIN_TRAFFIC_PILOT+OTHER1

The offset power is a constant defined in the protocol and related to Band Class.RC and so on.

V





The reverse power is estimated based on the

transmission amount of the forward link, but high error

will occur due to the irrelevance of forward and reverse

links.

The received power is affected by neighbor BTSs and

thus the high error occurs at the edge of the district.

The open loop power is the estimated value that is not

precise enough and needs the closed loop to rectify the

value.

Disadvantages of Reverse Open Loop Power Control





Reverse Closed Loop Power Control

The closed loop rectification indicates that based on the

estimation of the open loop, the MS can quickly rectify its

transmission power (800 times per second) according to

power control instruction received in the forward channel.

The closed loop verification is divided into:

inner loop

outer loop

After the closed loop

power control takes effect,

the transmission power of

the MS is obtained based

on reverse open loop

estimation and closed

loop adjustment.





Outer loop：The BSC obtains the set value of the Eb/Nt

based on the current FER Inner loop：The BTS fills the power bit in the traffic

frame based on the current reverse Eb/Nt

The reverse power control bits are sent through the

forward service channel.

Reverse Closed Loop Power Control





BTS

Channel Assnmt. Msg.

Origination Msg

Base Sta. Acknlgmt. Order

TFC frames of 000s

TFC preamble of 000s


Mobile Sta. Ackngmt. Order

Service Connect Msg.

Svc. Connect Complete Msg


Call is Established!

MSProbing

ACCESS

PAGING

FW TFC

PAGING

RV TFC

FW FC

RV TFC

FW TFC

RV TFC

FW TFC

Successful Access Attempt

Start point of the open loop power control

Start point of the closed loop

power control








Contents




Calculation of Forward Power Control

The power of the forward CDMA channel is shared by the pilot frequency,

synchronization, paging and service channels.

The intensity of the signal varies with the changes of distance from the SM

to the BTS. As the result, it is better to control the power distribution for

each traffic channel.

The standard specifies that the MS must monitor the quality of the forward

traffic channel. After receiving the instructions from the BTS, the MS

sends the messages to the MS. The closed loop process is similar with the

reverse power control.

Features of Forward Power Control





The forward power control is used for the BTS

Forward power control based on the

measurement report

Power control

Forward quick power control

Categories of the Forward Power Control




You can collect statistics on forward channel quality in the following modes based on the

system setting.

Threshold mode: When the number of the frame errors reaches the threshold

set by the system, the MS reports the PMRM message to the BTS. In this way,

the signals are decreased and the efficiency improved.

Cycle mode: When the number of the frame errors reaches the cycle frames

set by the system, the MS reports the PMRM messages to the BTS.

The MS can support the two modes at the same time. For sake of convenient processing,

the system does not support two modes at the same time at present.


Forward Power Control Based on Measurement Report




The BSC can adjust the forward channel based on the EIB in the reverse service

channel frame (reverse link frame) reported by the MS. The EIB indicates erasure

indicator bit and is used to judge the good and bad frames.

Note:

From the version3 of the protocol on, the reverse traffic channel frames of

RateSet2 contains the EIB.

EBI setting: When it is set to 0, it indicates that the frame is good and has

passed the CRC verification of the physical layer; if it is set to 1, it

indicates that the frame is bad and has not passed the CRC verification.


Theories of EIB Forward Power Control




Speed of calculating the EIB power control: 1 bit per 1 frame, that is, 50

times/second.

The good/bad frame is monitored on the F-FCH, the calculation delay of the EIB

power control is 2 frame in general.

To ensure the processing delay of different MSs, the EIB power control is put in

the first bit of the reverse service frame.



i-1 i i+1 i+2Received

Frames on

Forward

Fundamental or

Dedicated Control

Channel

20 ms

i-1 i i+1 i+2Reverse Power

Control

Subchannel20 ms

Power control bits set to '1' for

bad frame(s) or '0' for good frame(s)

i+2

C l l ti f F d P C t l




Frame Quality Counter Power Adjustment

Good EIB_CNT counter = 0 Rise EIB_UP_STEP，EIB_CNT counter

=PWR_EIB_CNT

EIB_CNT counter != 0 Unchanged power

Bad EIB_CNT counter = 0 Fall EIB_DWNS_STEP

EIB_CNT counter != 0 Fall EIB_DWNB_STEP



C l l ti f F d P C t l




Outer loop: The MS computes the forward

channel FER and then compares with the target

FER to get the target Eb/Nt.

Inner loop: The MS fills the power bit in the

subchannel of the reverse power control by

comparing the target Eb/Nt with the measuredEb/Nt.

The forward quick power control bit is sent

through the reverse pilot frequency channel.


Theories of Forward Quick Power Control




Definition Standards of Radio Configuration and Protocol Version of the MS

For the IS2000 and IS95/95B are backward compatible, the Rate Set1 and Rate

Set2 (as a subset of the IS2000) corresponds to RC1 and RC2.

Radio Configuration

Protocol Version of the MS

Protocol version of the MS:1-2:IS95, 3:IS95A,4-5:IS95B, 6:20001X




Application of the Power Control Calculation

Forward Power Control Is Based on the CDMA Standards:

The MS with version 2-5 is allocated with the RC1 channel and adopts themeasurement report power control.

The MS with version 3-5 is allocated with the RC2 channel and adopts the

EIB power control (prior choice) and the measurement report power control

as well.

The MS with version later than 6 (including 6) adopts forward quick power

control (prior choice) and measurement report and EIB control as well.

Application of the Reverse Power Control

The MS with version 2-7 adopts the same reverse power control calculation

(open loop and closed loop).

At present, the Huawei system automatically chooses the power control

calculation based on the protocol versions of the MS and radio

configuration.




Questions

What are the categories of the power control?

What are the mapping relations between the forward power

control and RC and the protocol version of the mobile phone?

What are the theories of the forward quick power control and

reverse quick power control?







Contents




Data Configuration of Power Control

Parameters: NOM_PWR, INIT_PWR, PWR_STEP

Brief Description: These parameters affect the power estimation of open loop power

control. Their influence begins at the first access probe transmission. They greatly

affect the access process and call establishment. For details, see CDMA 1x BSS

Parameter Configuration Guide and the previously described contents.

Relevant Information: APM

Balance Setting: If the values of the parameters are set too high, the parameters will

have great impact on the reverse capacity and redundant power is generated. If the

values are set too low, you may have to try many times before having the mobile phone

accessed to the channel and the access may even fail.

Supplement: Parameter NOW_PWR and parameter INI_PWR has the same impact on

the first accessed probe. The are different from the perspective of physics. The effect of

their impact on the later probes differs.

Command Line: MOD APM




Parameter: RLGAIN_ADJ (link gain adjustment)

Brief Description: After the access channel accesses the system, the initial power (the

reverse pilot frequency power for the IS2000) of the traffic channel = the power of the

current access channel + the value of the parameter

Relevant Information: ECAM

Balance Setting: The greater the parameter value is, the higher are the transmissionquality during the initial period of the call and the establish rate of the call. However

the parameter will have impact on the system capacity and increase the power

consumption of the mobile phone.

Command Line: MOD RCLPC





Parameters:

Reversely initialized set value: REV_INIT_SETPT

Maximum FCH outer loop set value: REV_MAX_FCH_SET_PT

Minimum FCH outer loop set value: REV_MIN_FCH_SET_PT

Brief Description: This group of parameters influence the initial, maximum

and minimum reverse outer loop set value.

Relevant Information: Parameters used by the system

Balance Setting: This group of parameters need to be balanced between

network index (such as voice quality and call drop rate) and system reverse

capacity. If the parameter values are set high, they will decrease the system

reverse capacity.

Command Line: MOD RCLPC





Parameters:

Minimum Eb/Nt value of the FCH

Maximum Eb/Nt value of the FCH

Initial Eb/Nt value of the FCH

Brief Description: This group of parameters respectively indicate the

minimize, maximize and initial set values of the forward FCH outer loop power control of the mobile phone.

Relevant Information: ECAM

Balance Setting: These values need to be balanced between the voice quality,

call drop rate and the forward system capacity. If they are set high, the voice

quality will be improved and the call drop rate decreased but decrease the

forward capacity.

Command Line: MOD FFASTPC






Parameters:

Initial power of the forward FCH

Maximum power of the forward FCH

Minimum power of the forward FCH

Brief Description: This group of parameters indicates the minimum, maximum and initial

values of the forward FCH transmission gains respectively.

Relevant Information: Parameters used by the system

Balance Setting: These parameters need to be balanced between the voice quality, call drop rate

and forward system capacity. If their values are set high, the voice quality will be improved and

the call drop rate decreased but decrease the forward capacity.

Supplement: Corresponding parameters can be set for different power control. For the IS2000,

its initial power can be obtained through the setting of the revised value of the forward FCH

initial power.

Command Line: MOD FSLOWPC for measurement report, MOD FEIBPC for the EIB power

control, and MOD FFASTPC for quick power control.






Synchronous Switch of the FCH Power

In the soft handoff, the ratios between the traffic channel powers of different

branches and the forward pilot frequency power are the same. The traffic channel

consists of the FCH and the SCH.

The synchronous switch is suggested to be started without A3/A7 soft handoff.

The synchronous switch is suggested to be closed with A3/A7 soft handoff, so are

the BSC and the BTS sides.

Note

V2R2 is not controlled by this synchronous switch.




Questions

What are the basic forward power control parameters? How are they used?

What are the basic reverse power control? How are they used?

What are the modification commands for the forward and reverse power control

respectively?




Summary


Categories of Power Control



Contents



Thank you!

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RG000003 CDMA1X Introduction to Power Control ISSUE2.1(New)