owj100106 wcdma power planning
DESCRIPTION
WCDMATRANSCRIPT
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.
Configuration principal
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.
Configuration principal
The success rate of UE getting the message form BCH achieved target
value
25 Internal Use
P-CCPCH(BCH)P-CCPCH(BCH)
Frame structure for Primary Common Control Frame structure for Primary Common Control Physical Channel Physical Channel
Tslot = 2560 chips , 20 bits
1 radio frame: Tf = 10 ms
(Tx OFF)
256 chips
Slot #14Slot #iSlot #1Slot #0
Data N data1=18 bits
26 Internal Use
P-CCPCH(BCH)P-CCPCH(BCH)
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
P-CCPCH(BCH)P-CCPCH(BCH)
Then the possibility of UE getting the information correctly in the N2th time at most is :
28 Internal Use
P-CCPCH(BCH)P-CCPCH(BCH)
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
Default value : -2dB
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)
1 radio frame: Tf = 10 ms
(TFCI)N bits
256 chips
Slot #14Slot #iSlot #1Slot #0
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
S-CCPCH(FACH)S-CCPCH(FACH)
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
S-CCPCH(FACH)S-CCPCH(FACH)
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
S-CCPCH(FACH)S-CCPCH(FACH)
828 )1(])1(1[ FACHFACH BLERBLER
36 Internal Use
S-CCPCH(FACH)S-CCPCH(FACH)
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
Configuration principal
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)
Default value : -6dB
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
Configuration principal
The possibility which UE can receive it’s paging indicator correctly should ac
hieve the target value
43 Internal Use
S-CCPCH(PCH) &PICHS-CCPCH(PCH) &PICH
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
S-CCPCH(PCH) &PICHS-CCPCH(PCH) &PICH
45 Internal Use
S-CCPCH(PCH) &PICHS-CCPCH(PCH) &PICH
Time intervals between PICH and SCCPCH
46 Internal Use
S-CCPCH(PCH) &PICHS-CCPCH(PCH) &PICH
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
S-CCPCH(PCH) &PICHS-CCPCH(PCH) &PICH
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
S-CCPCH(PCH) &PICHS-CCPCH(PCH) &PICH
LpPICHBER )1(1
PCHLp
PICHLp
PICH BLERBERBERq )1()1(1
PCHBLER
49 Internal Use
S-CCPCH(PCH) &PICHS-CCPCH(PCH) &PICH
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
Huawei Confidential. All Rights Reserved