OWJ100106 WCDMA Power Planning

Huawei Confidential. All Rights Reserved

WCDMA Power Planning

ISSUE 1.0

2 Internal Use

Power is the final radio resource in

WCDMA system. How to allocate the

power for different channel will affect the

capacity and coverage performance of

WCDMA system.

In this course, different power allocation

strategies are used for different channel

based on the structures.

3 Internal Use

ObjectObject

Upon completion this course, you will be able to:

Know the power configuration analysis of

downlink channels

Know the parameters configuration of

Downlink Channel Power

4 Internal Use

Power Configuration AnalysisPower Configuration Analysis

Purpose In Downlink, all users and the common channel shared the total transmissio

n power in one NodeB

Because of the limited transmission power, the reasonable power configurat

ion for common channels and dedicated channel plays an important role ab

out enhancing the capacity and coverage.

Power Control Dedicated Channel ： Inner loop power control, which is needed to set the

maximum and minimum transmission power.

Common Channel: No power control, and the transmission power are set w

hen the cell set up.

5 Internal Use

Downlink Common ChannelDownlink Common Channel

The common channel which are needed the power The common channel which are needed the power configuration are:configuration are:

CPICH P-CCPCH SCH(P-SCH,S-SCH) S-CCPCH PICH AICH

6 Internal Use

The factor which influenced powerThe factor which influenced power

Performance requirements Different common channel requires different BLER, Eb/No or Ec/Io

Processing Gain The channel processing gain means the gain from coding process and spreading

process during demodulation

The P-CCPCH 、 S-CCPCH have 3dB coding gain besides spreading gain

CPICH 、 PICH and AICH only have spreading gain

Since no spreading process for SCH, no spreading gain for SCH. But it is repeat

ed transmitted, this gain should be considered.

Propagation Environment Different environment, the relationship between BER/BLER and Eb/Io are differe

nt.

7 Internal Use

Power configuration AnalysisPower configuration Analysis

Under the condition of satisfied the coverage requirement, the less tran

smission power of each common channel, the better performance will b

e get.

Different channel request different Eb/No to obtain the BER/BLER requi

rements

Because different channel has different coding gain and spreading gain,

the corresponding Ec/Io will be different.

8 Internal Use

The problems about parameters configurationThe problems about parameters configuration

Problems: In protocol, the performance indices are not defined.

Each channel needs a performance index which is not mentioned in any

reference books

9 Internal Use

The power configuration for dedicated channelThe power configuration for dedicated channel

The maximum transmission power for single user should satisfied: Obtain the quality (BER/BLER) of services on the edge of cell

The coverage balance on both uplink and downlink: According to the maximum

transmission power of UE, the uplink coverage ability can be calculated. From

that, the downlink coverage ability and the coupling loss can be achieved. Then,

with the known downlink capacity, the downlink maximum transmission power for

single user can be calculated.

10 Internal Use

The power configuration for Dedicated channelThe power configuration for Dedicated channel

The formula for Pmax:

Where, Lmax is the downlink maximum coupling loss, is non-orthogon

al factor, Ptot.bs the total transmission power of a NodeB, Iother the int

erference caused by other base stations, Pn background noise, Pmax t

he maximum transmission power for a single service, Eb/N0 the thresh

old for a service

Notherbstot

b

PILP

LPNE

max

,

maxmax0

//

11 Internal Use

The power configuration for Dedicated channelThe power configuration for Dedicated channel

The threshold of downlink transmission power for a single user If the downlink transmission power for a single user is too strong on the

edge to cell, the downlink capacity will be decreased a lot.

Based on that, a maximum value for the downlink transmission power fo

r a single user should be set. This value has very close relationship with

the maximum coupling loss, the average coupling loss and the number

of users.

The lesser PmaxThreshold, the higher possibility of call drop will happen

ed. This value should satisfied the formula min{Pmax ， PmaxThreshol

d}

12 Internal Use

The power configuration for common channelThe power configuration for common channel

Configuration principal: The real cell coverage ability =min{ the common channel coverage abilit

y ， the dedicated channel coverage ability}

the common channel coverage ability should match to the dedicated cha

nnel coverage ability. If it is not enough, the coverage ability can not sati

sfied with the services. If it is too much, it will waste the power resource,

and decrease the downlink capacity because of the increased interfere

nce for own cell and adjacent cells

13 Internal Use

The power configuration for common channelThe power configuration for common channel

Configuration method According to the dedicated channel coverage requirement, the

maximum downlink coupling loss of common channel on the edge of cell

can be calculated.

After that, the required common channel transmission power can be

calculated according to the quality requirement of common channel.

14 Internal Use

PCPICHPCPICH

Function

In the third step of cell search, it is used for finding the specific

scrambling code from scrambling group.

It decides the area of cell search, cell selection, cell re-selection and

handover.

It can be used for channel estimation while receiving.

It decides the receiving performance of other dedicated and common

channel except SCH

It decides the coverage ability of other channels.

Configuration principle

The power is decided by the cell radius and environment.

The typical value is the 5%~10% of the total power of base station

It is a reference for configuring other common channel power value.

15 Internal Use

PCPICHPCPICH

Frame structure for Frame structure for CPICH CPICH

In CPICH, the transmission contents are already defined in protocol.

Tslot = 2560 chips , 20 bits

1 radio frame: Tf = 10 ms

Slot #14Slot #iSlot #1Slot #0

Pre-defined bit sequence

16 Internal Use

PCPICHPCPICH

CPICH Fixed rate,30kbps ， SF=256 ， No coding gain

For example, the maximum downlink transmission power for a single service is 3

0dBm. Considering the 3dB coding gain of dedicate channel, the CPICH transmis

sion power is 33dbm in order to provide the same coverage ability.

Reference configuration The range defined in protocol: -10 .. 50dBm

Default configuration: 33dBm

MML command ADD PCPICH

17 Internal Use

The transmission power of PCPICH should satisfied the following

formula

Where PCPICH is the transmission power which base station allocated, Ec CPIC

H should satisfied the normal cell search, handover and the stable

quality of dedicated channel and common channel.

After the EcCPICH and PCPICH are set, the cell coverage ability can be obtaine

d by the downlink maximum coupling loss Lmax

PCPICHPCPICH

0,

// NEPI

LP

LPcCPICH

Notherbstot

CPICH

18 Internal Use

According to the downlink maximum coupling loss, the transmission

power of other channels except SCH can be calculated by the following

formula:

Where, PDLCH is the downlink transmission power of a common channel,

Ec/N0DLCH is the SIR which should satisfied the quality of the common channel

PCPICHPCPICH

)]([ 0max,0

NILPNEP otherbstot

DLCH

cDLCH

19 Internal Use

SCHSCH

P-SCH Function

In the first step, it is used for time slot synchronization

Configuration principal

the time slot synchronization success rate should be satisfied the

requirement

S-SCH Function

In the second step of cell search, it is used for frame synchronization and

scrambling code group identification.


the frame synchronization success rate should be satisfied the requirement

20 Internal Use

Synchronization Procedure—Cell SearchSynchronization Procedure—Cell Search

Slot synchronization

Frame synchronization and code-group identification

Scrambling-code identification

UE uses PSC to acquire slot synchronization to a cell

UE uses SSC to find frame synchronization and identify the code group of the cell found in the first step

UE determines the primary scrambling code through correlation over the CPICH with all codes within the identified group, and then detects the P-CCPCH and reads BCH information。

21 Internal Use

As for the PSCH and SSCH ， the orthogonal factor do not need to be

considered because the OVSF code is not used for the channels. The transmissi

on power is :

Since the SCH channels is not spread, it increased the interference to other chan

nels.

The transmission power can not be larger. The value can be get from the succes

s rate of time slot synchronization, frame synchronization and

scrambling group identification.

SCHSCH

)]([ 0max,0

NILPNEP otherbstot

SCH

cSCH

22 Internal Use

SCHSCH

Structure of Synchronisation Channel Structure of Synchronisation Channel (SCH) (SCH)

PSC is a known sequence. For all cells, the PSC are same. The length is 16 chips, and it is repeated 256 times to transmitted at the first 256 chips of each time slot.

PrimarySCH

SecondarySCH

256 chips

2560 chips

One 10 ms SCH radio frame

Slot #0 Slot #1 Slot #14

ac si,0

ac p

ac si,1

ac p

ac si,14

ac p

23 Internal Use

SCHSCH

SCH No coding

The gain is from transmission repeatedly

Considering any time slot of SCH can be used for cell search and UE can restart

the process at next time slot if failed, the power of SCH can be decreased

Reference configuration The value range defined in protocol: -35..+15dB

In the test environment defined in 25.133, the power of SCH is -2dB

Default value ： -5dB

MML command ADD PSCH

ADD SSCH

24 Internal Use

P-CCPCH(BCH)P-CCPCH(BCH)

P-CCPCH(BCH) Function

The system information is broadcasted in this channel, which is used for

the process of cell selection, cell re-selection, access , handover etc.

BCCH can only be transmitted by the TM mode. If UE can not decode

the information correctly, it will retry.


The success rate of UE getting the message form BCH achieved target

value

25 Internal Use


Frame structure for Primary Common Control Frame structure for Primary Common Control Physical Channel Physical Channel

Tslot = 2560 chips , 20 bits


(Tx OFF)

256 chips


Data N data1=18 bits

26 Internal Use


BCH

The length of system information block is different from the different type of

information. The maximum number of TB for a integrated one can be 16.

Assume the number is 3 and the BLER is BLERPCCPCH, then the

possibility of UE getting the information correctly in the first time is p = (1-

BLERPCCPCH )3 , and the q=1- (1-BLERPCCPCH )3

Channel coding CRC length TTI

convolution 16 bit 20ms

27 Internal Use


Then the possibility of UE getting the information correctly in the N2th time at most is ：

28 Internal Use


PCCPCH(BCH) SF ＝ 256

½ convolutional coding, so more gain can be get compare to CPICH

Reference configuration The value range defined in protocol: -35 .. +15dB

With 3dB coding gain of P-CCPCH, the transmission power can be less

3dB than PCPICH


MML ADD BCH

29 Internal Use

S-CCPCHS-CCPCH

Frame structure for Secondary Common Control Frame structure for Secondary Common Control Physical Channel Physical Channel

Tslot = 2560 chips , 20*2 bits （ k ＝ 0…6)


(TFCI)N bits

256 chips


Data N data1 bits(TFCI)

PolitN bits Polit

k

30 Internal Use

S-CCPCHS-CCPCH

One cell can support 1 or 2 SCCPCH channels

SCCPCH A.) carrier 1 PCH and 3 FACHs （ Transportation signaling, traffic data

and CTCH ）； B.) carrier two FACH （ Transportation signaling, traffic data ）； C.) Carrier PCH ； D.) carrier 1 PCH and 2 FACHs （ Transportation signaling, traffic data ）； Etc 。

31 Internal Use

S-CCPCHS-CCPCH

FACH Coding Method Rate Match CRC Length TTI

Signaling Convolution(1/2) 220 16bits 10ms

Data Turbo 130 16bits 10ms

DTCH Convolution(1/3) 220 16bits 10ms

Coding Method Rate Match CRC Length TTI

Convolution(1/2) 230 16bits 10ms

PCPCHH

FACHFACH

32 Internal Use

S-CCPCH(FACH)S-CCPCH(FACH)

S-CCPCH(FACH) Function

RRC CONNECTION SETUP message is sent on this channel by

RNC, which influenced the RRC connection establishment

Transmit low data rate service

Configuration principal:

The success rate which UE received RRC CONNECTION SETUP

achieved the target value

The BLER of data service achieve the target value

33 Internal Use


RRC connection establishment process The RRC_CONECTION_REQUEST is sent on PRACH by UE ：

UE will retransmit the REQUEST message if the SETUP

message is not arrived in T300 （ the default value is 1000ms ） If the retransmitted times is beyond N300(the default value is 3) ，

the establishment failed ； RRC_CONECTION_SETUP is sent on SCCPCH by UTRAN ；

The reasons for retransmission RRC_CONECTION_REQUEST is not received by UTRAN correctly ； RRC_CONECTION_SETUP is not received by UE ；

34 Internal Use

Assume: The possibility which UE received the RRC_CONNECTION_SETUP message

correctly is

The BLER of PRACH message part is

The number of TB of PRACH Message is 1, and the FACH one is 8

The BLER of SCCPCH is BLERFACH, then the possibility which UE

received the RRC_CONNECTION_SETUP correctly is:

Where p is the , the q is the


3

1

13 )1(

n

n pqpqx

8)1( FACHBLER

x3PRACHBLER

PRACHBLER1

35 Internal Use

So, the lowest possibility which can receive the RRC_Connection_Setup message for FACH can be calculated by the following formula:

This formula means the possibility is in the worst condition

The worst situation is the three retransmission are all caused by the

FACH, and UE has to receive the RRC_Connection_Setup message

correctly on the third time


828 )1(])1(1[ FACHFACH BLERBLER

36 Internal Use


Reference configuration The value range ： -35 ～ 15dB

Default value: -1dB

MML ADD FACH

37 Internal Use

AICHAICH

AICH Function

AI is sent from this channel by RNC


On the edge of cell, the possibility which UE can get the

AI correctly satisfies the target value

38 Internal Use

AICHAICH

Structure of Acquisition Indicator Structure of Acquisition Indicator Channel (AICH) Channel (AICH)

20 ms

AS #14AS #iASt #1ASt #0AS #14 ASt #0

a0 a1 a2 a30 a31 Transmission Off

A1 part=4098 Chips,32 real-valued syTTbols 1024 Chips

39 Internal Use

a0, a1, …, a31 can be calculated by the following formula:

where AIs is acquisition indicator of the sth signature ， which can be +1, -1, or 0. the values corresponds to acquisition successfully, failed or no reponse (when the AI is an unusable one for corresponding signature of PRACH). The sequences bs,0, …, bs,31 is given by following table ：

AICHAICH

40 Internal Use

AICHAICH

If UE detected the AIS in corresponding signature is 1 ， it shows the acces

s process succeed. Then, the UE can transmit the message part.

If UE detected the AIS in corresponding signature is -1, it shows the access process is refused, UE transmit the “Nack on AICH received” to MAC ， Wait for （ 10ms+NB01*10ms ， 3 NBO1 10 ）， then try again

If UE detected the AIS in corresponding signature is 0 Retransmit a preamble with higher power, （ the power increase should less than

6dB ） If the retransmission times is beyond the maximum number or receive a right acq

uisition indicator, UE exits the random access process

41 Internal Use

AICHAICH

AICH No coding

SF ＝ 256

Reference configuration The value range: -10 .. +5dB

In the environment defined in 25.133, the ratio of Ec of AICH to total transmis

sion power is -10db. That is to say, the transmission power of AICH should b

e the same as the CPICH. Considering the maximum number of AI is 16, eac

h AI power can be only 1/16 CPICH power(-12db)


MML MOD AICHPWROFFSET

42 Internal Use

S-CCPCH(PCH) &PICHS-CCPCH(PCH) &PICH

S-CCPCH(PCH) Function

The paging message is sent by RNC from this channel

Configuration principal ； The possibility which UE can receive it’s paging message correctly should ac

hieve the target value

PICH Function

The paging indicator is sent from this channel by RNC


The possibility which UE can receive it’s paging indicator correctly should ac

hieve the target value

43 Internal Use


Structure of Paging Indicator Channel (PICH)

Each PICH frame has NP Paging indicators, NP （ the number of paging indica

tions per frame ） defines how many paging indicators can be supported in one

PICH frame. UE can get this value from system information. The value of NP ca

n be 18 ， 36 ， 72 ， 144 ， which means the 288 bits is divided by NP ， and

each one, also means each PI, has 288/NP bits.

44 Internal Use

The mapping relationship between {PI0, .., PIN-1} and PICH bits {b0,..,

b287} is shown as following table

UE can calculate which Np is corresponding to its paging indicator p


45 Internal Use


Time intervals between PICH and SCCPCH

46 Internal Use


Assume the paging success rate from CS domain and PS domain is

The times of retransmission from UTRAN is NrepeatRAN ； and the one

form CN is NrepeatCN

The Number of PI per frame is Np ， and corresponding paging indicato

r is Lp=288/Np ；

x5

47 Internal Use


In access process, the paging type on PCH is Page type 1. Each pa

ging message need 1 TB. Assume the BLER which UE received the

PCH message is BLERPCH ， and the BER of PICH is BERPICH 。If there is no paging response, the maximum retransmission time is

Npageall=NrepeatRAN * NrepeatCN

If the UE did not receive any paging message in a single paging proc

ess, the reasons only could be ：

48 Internal Use

Not receive PICH correctly, and the possibility is

Not receive PCH correctly, and the possibility is

So the possibility which UE can not receive paging message correctly is


LpPICHBER )1(1

PCHLp

PICHLp

PICH BLERBERBERq )1()1(1

PCHBLER

49 Internal Use


Then the success rate is p=1-q ， the possibility which UE can

receive the paging message correctly after Npageall

retransmissions is:

pageallN

i

i pqx0

5

50 Internal Use

PICH and PCHPICH and PCH

PICH reference configuration The value range ： -10 .. +5dB

Default configuration: -7dB

PCH reference configuration The value range: -35 ～ 15dB

Default configuration: -2dB

MML ADD CHPWROFFSET

ADD PCH

OWJ100106 WCDMA Power Planning

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