Huawei WCDMA Power Planning

Huawei Confidential. All Rights Reserved

WCDMA Power Planning

ISSUE 1.0

Internal Use2

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.

Internal Use3

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

Internal Use4

Power Configuration AnalysisPower Configuration Analysis

Purpose

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

transmission power in one NodeB

Because of the limited transmission power, the reasonable power

configuration for common channels and dedicated channel plays an

important role about 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

when the cell set up.

Internal Use5

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

Internal Use6

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

repeated transmitted, this gain should be considered.

Propagation Environment

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

different.

Internal Use7

Power configuration AnalysisPower configuration Analysis

Under the condition of satisfied the coverage requirement, the less

transmission power of each common channel, the better performance

will be get.

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

requirements

Because different channel has different coding gain and spreading gain,

the corresponding Ec/Io will be different.

Internal Use8

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

Internal Use9

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.

Internal Use10

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-

orthogonal factor, Ptot.bs the total transmission power of a NodeB,

Iother the interference caused by other base stations, Pn background

noise, Pmax the maximum transmission power for a single service,

Eb/N0 the threshold for a service

Notherbstot

b

PIL

PLP

NE

max

,

maxmax0

//

Internal Use11

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

for 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

happened. This value should satisfied the formula

min{Pmax ， PmaxThreshold}

Internal Use12

The power configuration for common channelThe power configuration for common channel

Configuration principal:

The real cell coverage ability =min{ the common channel coverage

ability ， the dedicated channel coverage ability}

the common channel coverage ability should match to the dedicated

channel coverage ability. If it is not enough, the coverage ability can not

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

resource, and decrease the downlink capacity because of the increased

interference for own cell and adjacent cells

Internal Use13

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.

Internal Use14

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.

Internal Use15

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

Internal Use16

PCPICHPCPICH

CPICH

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

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

30dBm. Considering the 3dB coding gain of dedicate channel, the CPICH

transmission 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

Internal Use17

The transmission power of PCPICH should satisfied the following

formula

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

CPICH 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

obtained by the downlink maximum coupling loss Lmax

PCPICHPCPICH

0,

//

NEPI

L

PLP

cCPICH

Notherbstot

CPICH

Internal Use18

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

NILPN

EP otherbstot

DLCH

cDLCH

Internal Use19

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

Internal Use20

Synchronization Procedure—Cell SearchSynchronization Procedure—Cell Search 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。

Internal Use21

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

transmission power is :

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

channels.

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

success rate of time slot synchronization, frame synchronization and

scrambling group identification.

SCHSCH

)]([ 0max,0

NILPN

EP otherbstot

SCH

cSCH

Internal Use22

SCHSCH

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

Internal Use23

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


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

Internal Use24

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

Internal Use25


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

Internal Use26


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

Internal Use27


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

Internal Use28


PCCPCH(BCH)

SF ＝ 256

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


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

Internal Use29

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

Internal Use30

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 。

Internal Use31

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

Internal Use32

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

Internal Use33


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 ；

Internal Use34

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

x3

PRACHBLER

PRACHBLER1

Internal Use35

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

Internal Use36



The value range ： -35 ～ 15dB

Default value: -1dB

MML

ADD FACH

Internal Use37

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

Internal Use38

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

Internal Use39

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

Internal Use40

AICHAICH

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

access 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

acquisition indicator, UE exits the random access process

Internal Use41

AICHAICH

AICH

No coding

SF ＝ 256


The value range: -10 .. +5dB

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

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

should be the same as the CPICH. Considering the maximum number of AI

is 16, each AI power can be only 1/16 CPICH power(-12db)


MML

MOD AICHPWROFFSET

Internal Use42

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

achieve 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

achieve the target value

Internal Use43


Structure of Paging Indicator Channel (PICH)

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

indications 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 can 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.

Internal Use44

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


Internal Use45


Time intervals between PICH and SCCPCH

Internal Use46


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

indicator is Lp=288/Np ；

x5

Internal Use47


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

paging 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

process, the reasons only could be ：

Internal Use48

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

Internal Use49


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

Internal Use50

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

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Huawei WCDMA Power Planning