Wcdma power control

Table of Contents

Chapter 1 Power Control..............................................................................................................1

Huawei Technologies Proprietary

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List of Figures

Figure 1.2Power control configuration model (1)........................................................................6








Figure 1.10PRACH preamble and message parts......................................................................10

Figure 1.11Uplink open-loop power control on PRACH............................................................11

Figure 1.12Downlink open-loop power control on the DPDCH................................................40

Figure 1.13Uplink inner-loop power control...............................................................................46

Figure 1.14Downlink inner-loop power control..........................................................................51

Figure 1.15Uplink outer-loop power control procedure............................................................57

Figure 1.16Downlink power balance...........................................................................................66


ii

List of Tables

Table 1.1NEs required for power control......................................................................................4

Table 1.2Product versions.............................................................................................................4

Table 15.1Outer-loop Power Control Parameters on RAB basis..............................................65

Table 16.1Commands for the reconfiguration on the RNC side...............................................71


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Chapter 1 Power Control

1.1 Summary of Updates

This section provides the update history of this manual and introduces the contents of
subsequent updates.

Manual Version Description

01 (2006-9-26) Modified the principles to adjust SIR target in case of multi-
service.

02 (2006-9-28) Add description to the Rate Matching.

1.2 Introduction

The WCDMA system is a self-interfered system. The most important way to restrain
system interference level is the power control, especially in the uplink direction.
Without power control, a single overpowered UE could block a whole cell.

1.2.1 Definition

The power control is performed by the UE or UTRAN to adjust and control the power
of transmit signals according to the changes of channel environment and the quality
of receive signals.

In the WCDMA system, the power control mechanism comprises the following parts:

 Open-loop power control: Applicable in UL and DL. It sets the initial uplink and
downlink transmit power. Open-loop power control is used on physical channels
such as PRACH, DPCH.
 Inner-loop power control: Applicable in UL and DL. It directly adjusts the uplink
and downlink transmit power using power control commands. The inner loop
power control is performed by each UE and NodeB with the frequency of 1500
times per second (1.5 kHz).
 Outer-loop power control: Applicable in UL and DL. It indirectly controls the
uplink and downlink transmit power by increasing or decreasing the target SIR
value.


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 DL power balance: It is used to reduce the downlink power drifting of a given
UE during soft handover.

1.2.2 Purpose

The purpose of power control is to adjust the uplink and downlink power to the
minimum while ensuring the QoS.

 In the uplink, if a UE near the NodeB has too large a transmit power, it may
cause great interference to other UEs on the edge of the cell or even block the
whole cell. This is called near-far effect. In that case, uplink power control is
needed.
 In the downlink, the system capacity is determined by the total required code
power for each connection. Therefore, it is necessary to keep the transmit power
at the lowest level while ensuring signal quality at the receiving end for each UE.
In that case, the downlink power control is needed.
 Power control can be used against shadow fading and fast fading.
 Power control can increase system capacity.
 Power control for power drifting can improve the soft handover performance in
the downlink.

1.2.3 Terms and Abbreviations

I. Terms

None.

II. Abbreviations

Abbreviation Full Spelling

3GPP 3rd Generation Partnership Project

AMR Adaptive MultiRate

BER Bit Error Rate

BLER Block Error Rate

CDMA Code Division Multiple Access

CPCH Common Packet Channel

CPICH Common Pilot Channel

DCH Dedicated Channel

DL Downlink


2

Abbreviation Full Spelling

DPB Downlink Power Balance

DPCCH Dedicated Physical Control Channel

DPCH Dedicated Physical Channel

DPDCH Dedicated Physical Data Channel

FDD Frequency Division Duplex

FER Frame Error Rate

LMT Local Maintenance Terminal

MML Man-Machine Language

MRC Maximum Ratio Combining

OLPC Outer-Loop Power Control

PCA Power Control Algorithm

P-CPICH Primary Common Pilot Channel

PRACH Physical Random Access Channel

RAN Radio Access Network

RNC Radio Network Controller

RRC Radio Resource Control

RSCP Received Signal Code Power

RTWP Received Total Wideband Power

SHO Soft Handover

SIR Signal-Interference Ratio

SRNC Serving RNC

TFCI Transport Format Combination Indicator

TPC Transmit Power Control

UE User Equipment

UL Uplink

UMTS Universal Mobile Telecommunications System

UTRAN UMTS Terrestrial Radio Access Network

Uu Uu Interface

WCDMA Wideband CDMA


3

1.3 Availability

1.3.1 Involved Network Element

1.3.1 shows the Network Elements (NEs) required for power control.

Table 1.1NEs required for power control

UE NodeB RNC MSC Server MGW SGSN GGSN HLR

√ √ √ - - - - -

Note:

 - = NE not required

 √ = NE required

1.3.2 Software Release

1.3.2 describes the versions of the HUAWEI UMTS RAN products that support power
control.

Table 1.2Product versions

Product Version

RNC BSC6800 V100R002 and later releases

NodeB DBS3800 V100R006 and later releases

BTS3812A V100R002 and later releases

BTS3812E V100R002 and later releases

1.3.3 Miscellaneous

None.


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1.4 Impact

1.4.1 On System Performance

Power control improves the system capacity and ensures the QoS.

1.4.2 On Other Features

None.

1.5 Restrictions

None.

1.6 Technical Description

Power control in the uplink and the downlink is different. UL power control and DL
power control are separately described.

1.6.1 Power Control Configuration Model

The configuration model for power control is as show in 1.6.1, 1.6.1, 1.6.1, 1.6.1,
1.6.1, 1.6.1, 1.6.1 and 1.6.1.


5

RNC

RadioClass

GlobalParaClass RAB&SRBClass CellClass

FRC.Class PSCH.Class CELL.Class

CORRMALGOSWITCH.Class SSCH.Class PCPICH.Class

OLPC.Class BCH.Class PRACHBASIC.Class

DPB.Class FACH.Class PRACHUUPARAS.Class

TYPRABBASIC.Class SCCPCH.Class AICH.Class

TYPRAB.Class CHPWROFFSET.Class RACH.Class

TYPSRBBASIC.Class AICHPWROFFSET.Class PRACHTFC.Class

TYPSRB.Class PICHPWROFFSET.Class CELLCAC.Class

TYPSRBOLPC.Class CELLRLPWR.Class CELLSETUP.Class

TYPRABOLPC.Class CELLOLPC.Class

TYPSRBSEMISTATICTF.Class

TYPRABSEMISTATICTF.Class

Figure 1.2Power control configuration model (1)


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CELLCAC.Class FRC.Class

Max UL TX power of conversational service TFCI power offset

Max UL TX power of streaming service TPC power offset

Max UL TX power of interactive service Pilot power offset

Max UL TX power of background service Power control algorithm selection

RRC Proc DPDCH PC preamble length UL closed loop power control step size

RRC Proc SRB delay DL power control mode

HHO Proc DPDCH PC preamble length FDD DL power control step size

HHO Proc SRB delay Constant value configured by default

Initial power offset for SHO


CELLRLPWR.Class RACH.Clsass

RL Max DL TX power Max preamble loop

RL Min DL TX power Random back-off lower limit

Random back-off upper limit


PRACHTFC.Class CELLSETUP.Clsass

Power offset Power increase limit

ADD PRACHTFC DL power window average size

Gain Factor BetaD DL power control mode 1



7

PICHPWROFFSET PRACHBASIC.Class

PRACHUUPARAS.Class
CHPWROFFSET.Class

AICHPWROFFSET.Class Power increase step

Max preamble retransmission
AICH power offset
Constant value for calculating initial TX power
PICH power offset


TYPRABOLPC.Class DPB.Class

TYPSRBOLPC.Class DPB measurement report period

DPB measurement filter coefficient
BLER target value
DPB triggering threshold
SIR adjustment step
DPB stop threshold
Maximum SIR increase step
Ratio for max power
Maximum SIR decrease step
DPB adjustment ratio
Maximum SIR target
DPB adjustment period
Minimum SIR target
Max DPB adjustment step



8

TYPRAB.Class BCH.Class

TYPRABBASIC.Class PSCH.Class

TYPSRB.Class PCPICH.Class

TYPSRBBASIC.Class
CELL.Class
Reference BetaC

Reference BetaD PCPICH transmit power

AICH.Class PSCH transmit power

AICH transmission timing BCH transmit power

TYPRABSEMISTATICTF.Class TYPSRBSEMISTATICTF.Class

UL rate matching attribute DL rate matching attribute


SSCH CELL.Class FACH.Class

SSCH transmit power PCH.Class

SCCPCH.Class

CELLSELRESEL.Class
PCH power
Max allowed UE UL TX power
Max transmit power of FACH
CORRMALGOSWITCH.Class

Power control algorithm switch OLPC.Class

CELLOLPC.Class
TYPSRBOLPC.Class

SIR init target value SIR measurement filter coefficient

OLPC adjustment period SIR adjustment coefficient


1.6.2 Open-Loop Power Control

Based on the measurement acquirement of receive power, open-loop power control
attempts to make a rough estimation of path loss by means of a downlink signal, and
then to provide a coarse initial power setting of the UE and the NodeB at the


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beginning of a connection.

I. Uplink Open-Loop Power Control

1) Uplink Open-Loop Power Control on PRACH

The PRACH random access process is comprised of two different parts that the UE
will send to the system: preamble part and message part.

AICH access
slots RX at UE

One access slot
Acq.
Ind.

τ
PRACH access
slots TX at UE
p-a

Pre- Pre-
amble amble Message part

τp-p τp-m

Figure 1.10PRACH preamble and message parts

The preamble part is at the length of 4096 chips and consists of 256 repetitions of a
signature that is 16–chip long. There are a maximum of 16 signatures available.

The message part is 10 or 20 ms long and is comprised of a control part and a data
part. The data and control parts are transmitted in parallel. Once the UE receives an
answer on the corresponding AICH, it will send the message part of the PRACH.

Therefore, the parameters related to the UE access on the PRACH involve three
parts:

 Initial power calculation for the first preamble
 Power ramping for preamble retransmission
 Power setting for message part


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1 Initial Power Calculation for the First Preamble

To determine the initial power of the UE on its first PRACH preamble transmission,
both UE and UTRAN are involved, as shown in 1.

BCH :
•CPICH channel power
• UL interference level

RACH

•Measure CPICH_RSCP
•Determine the initial transmitted power

Figure 1.11Uplink open-loop power control on PRACH

Prior to PRACH transmission, the UE shall acquire the System Information Block
(SIB) that includes "Primary CPICH Tx power", “UL interference”, and “Constant
value”.

The UE measures the value for the CPICH_RSCP and calculates the initial power for
the first PRACH preamble with the following formula:

Preamble_Initial_Power (PRACH) = PCPICH TRANSMIT POWER - CPICH_RSCP +
UL interference + CONSTANT VALUE FOR CALCULATING INITIAL TX POWER

Where:

 The PCPICH TRANSMIT POWER parameter defines the PCPICH transmit
power in a cell. It is broadcast in SIB 5.


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Parameter name PCPICH transmit power

Parameter ID PCPICHPOWER

GUI range -100–500

Physical range& unit -10–50, step: 0.1 (dBm)

Default value 330

Optional / Optional
Mandatory

MML command ADD PCPICH/ MOD CELL

Description:

This parameter should be set based on the actual system environment such as cell
coverage (radius) and geographical environment. For the cells to be covered, the
downlink coverage should be guaranteed as a premise. For the cells requiring soft
handover area, this parameter should satisfy the proportion of soft handover areas
stipulated in the network planning. If the maximum transmit power of the PCPICH
is configured too great, the cell capacity will be decreased because a lot of system
resources will be occupied and the interference with the downlink traffic channels
will be increased.

Recommendation:

PCPICH TRANSMIT POWER is related to the downlink coverage in the network
planning. The default setting is 330, namely 33 dBm. If this parameter is too small,
it will influence directly the downlink pilot coverage range; if it is too big, the
downlink interference will increase, and the transmit power that can be distributed
to the services will be reduced, which will affect the downlink capacity. Meanwhile,
the configuration of this parameter also has influence on the distribution of
handover areas.

 CPICH_RSCP is the received signal code power, the received power on one
code measured on the primary CPICH. It is measured by the UE.
 UL interference is the UL RTWP measured by the NodeB, including noise
generated in the receiver, within the bandwidth defined by the receiver pulse
shaping filter. It is broadcast in SIB 7.
 The CONSTANT VALUE FOR CALCULATING INITIAL TX POWER parameter
compensates for the RACH processing gain. It is broadcast in SIB 5.


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Parameter name Constant value for calculating initial TX power

Parameter ID CONSTANTVALUE

GUI range -35–-10.

Physical range& unit dB

Default value -20

Optional / Mandatory Optional

MML command ADD PRACHBASIC/MOD PRACHUUPARAS

Description:

It is used to calculate the transmit power of the first preamble in the random access
process.

2 Power Ramping for Preamble Retransmission

If no positive or negative acquisition indicator on AICH is received by the UE from the
network after a given period, then the UE shall increase the preamble power by
POWER INCREASE STEP so that the Node-B can detect it, and re-send the
preamble. This “ramping up” process is characterized below:

 AICH transmission timing: In order to avoid too many collisions and consider the
processing capability of NodeB, it is specified in 3GPP that a UE shall wait at
least 3 or 4 access slots between the transmissions of 2 consecutive preambles,
according to the parameter AICH TRANSMISSION TIMING.
 Power increment step: Each time the UE re-transmits a preamble, the transmit
power is increased by POWER INCREASE STEP, compared to the previous
transmitted preamble.
 Maximum number of transmitted preambles: This limitation is defined by MAX
PREAMBLE RETRANSMISSION and MAX PREAMBLE LOOP parameters.
MAX PREAMBLE RETRANSMISSION defines the maximum number of
transmitted preambles allowed within an access cycle, and MAX PREAMBLE
LOOP defines the maximum number of random access preamble cycles. An
access cycle is defined by a number of radio frames on which the PRACH
access (and therefore a preamble ramping cycle) is allowed on specific slot
numbers.


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Parameter name AICH transmission timing

Parameter ID AICHTXTIMING

GUI range 0–1

Physical range& unit None

Default value 1


MML command ADD AICH

Description:

The transmission timing information of an AICH. "0" indicates that there are 7680
chips offset between the access preamble of the PRACH and AICH; "1" indicates
that there are 12800 chips offset between them.

Caution:

In order to change the value of the AICH TRANSMISSION TIMING parameter, the
cell shall be firstly de-activated through DEA CELL.
After the old configuration of AICH is deleted through RMV AICH, a new AICH can be
established through ADD AICH.

Parameter name Power increase step

Parameter ID POWERRAMPSTEP

GUI range 1–8


Default value 2



Description:

The power increase step of the random access preambles transmitted before the
UE receives the acquisition indicator in the random access process.


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Recommendation:

If the value of POWER INCREASE STEP is too big, the access process will be
shortened, but the probability of wasting power will be bigger; if it is too small, the
access process will be lengthened, but transmitting power will be saved. It is a
value to be weighed.

Parameter name Max preamble retransmission

Parameter ID PREAMBLERETRANSMAX

GUI range 1–64


Default value 20



Description:

The maximum number of preambles transmitted in a preamble ramping cycle.

Recommendation:

The product of the MAX PREAMBLE RETRANSMISSION parameter and the
above-mentioned PRACH POWER INCREASE STEP determines the maximum
ramp power of the UE within a preamble ramp cycle.

If this value is too small, the preamble power may fail to ramp to the required
value, resulting in UE access failure; if it is too big, the UE may repeatedly increase
the power and make access attempts, resulting in interference to other users.


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Parameter name Max preamble loop

Parameter ID MMAX

GUI range 1–32


Default value 8


MML command ADD RACH/MOD RACH

Description:

The maximum number of random access preamble loops.

Caution:

In order to change the value of the MAX PREAMBLE LOOP parameter, if the current
cell is on-going and there is one and only one PRACH in this cell, the cell shall be
firstly de-activated through DEA CELL.

The ramping process stops until the number of transmitted preambles has reached
the MAX PREAMBLE RETRANSMISSION within an access cycle, or when the
maximum number of access cycles MAX PREAMBLE LOOP is reached.

When a negative acquisition indicator on AICH is received by the UE, which indicates
rejection of the preamble, the UE shall wait for a certain back-off delay and re-initiate
a new random access process. Two parameters RANDOM BACK-OFF LOWER
LIMIT and RANDOM BACK-OFF UPPER LIMIT are defined respectively as the lower
and upper bounds of the random access back-off delay.


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Parameter name Random back-off lower limit

Parameter ID NB01MIN

GUI range 0–50


Default value 0



Description:

The lower limit of random access back-off delay.

Parameter name Random back-off upper limit

Parameter ID NB01MAX

GUI range 0–50


Default value 0



Description:

The upper limit of random access back-off delay.

Configuration Rule and Restriction:
RANDOM BACK-OFF LOWER LIMIT shall not be set bigger than RANDOM
BACK-OFF UPPER LIMIT.

If RANDOM BACK-OFF LOWER LIMIT = RANDOM BACK-OFF UPPER LIMIT, it
means that the retransmission periodicity of preamble part is fixed.


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Caution:

In order to change the value of the RANDOM BACK-OFF LOWER LIMIT or
RANDOM BACK-OFF UPPER LIMIT parameter, if the current cell is on-going and
there is one and only one PRACH in this cell, the cell shall be firstly de-activated
through DEA CELL.

3 Power Setting for Message Part

When the UE has received a positive acquisition indicator on AICH, it will transmit the
random access message using three or four uplink access slots after the uplink
access slot of the last transmitted preamble, depending on the AICH transmission
timing parameter. This message is made up of a control part and a data part:

 Control part: The transmit power of the control part of the random access
message should be POWER OFFSET higher than the power of the last
transmitted preamble.
Parameter name Power offset

Parameter ID POWEROFFSETPPM

GUI range -5–10


Default value Values according to PRACH TFC

Optional / Mandatory
Mandatory

MML command ADD PRACHTFC

Description:

The power offset between the last access preamble and the message control part.
The power of the message control part can be obtained by adding the offset to the
access preamble power.

POWER OFFSET must be set for each instance of PRACH TFC.


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Recommendation:

It is recommended that the value of POWER OFFSET corresponding to the TFC
for signaling transmission is set to -3 dB, and that corresponding to the TFC for
service transmission is set to -2 dB.

If the value of POWER OFFSET is set too low, it is likely that the signaling or the
service data carried over the RACH can not be correctly received, which affects
the uplink coverage. If the value is set too high, the uplink interference is
increased, and the uplink capacity is affected.

Caution:

In order to change the value of the POWER OFFSET parameter, if the current cell is
on-going and there is one and only one PRACH in this cell, the cell shall be firstly de-
activated through DEA CELL.

 Data part: The message part of the uplink PRACH channel employs gain factors
to control the control/data part:
a) GAIN FACTOR BETAC (βc) is the gain factor for the control part.

b) GAIN FACTOR BETAD (βd) is the gain factor for the data part.

Parameter name Gain Factor BetaC

Parameter ID GAINFACTORBETAC

GUI range 1–15


Default value None

Optional / Mandatory Mandatory


Description:

The power occupancy factor of the control part.


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Parameter name Gain Factor BetaD

Parameter ID GAINFACTORBETAD

GUI range 1–15


Default value None

Optional / Optional
Mandatory


Description:

The power occupancy factor of the data part.

PRACH CTFC POWER OFFSET GAIN FACTOR GAIN FACTOR
BETAC BETAD

0 -3 13 15

1 -2 10 15

Either Gain Factor BetaC or Gain Factor BetaD must be set to 15 for each
instance of power difference between control and data part of PRACH.

Caution:

In order to change the value of the GAIN FACTOR BETAC or GAIN FACTOR
BETAD parameter, if the current cell is on-going and there is one and only one
PRACH in this cell, the cell shall be firstly de-activated through DEA CELL.

2) Uplink Open-Loop Power Control on DPCCH

The UL open-loop power control on dedicated channel aims to determine the initial
power of the first uplink DPCCH.


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When setting up the first DPCCH, the UE shall start the UL inner loop power control
at a power level and set the initial power of uplink DPCCH with the following formula:

DPCCH_Initial_Power = DPCCH_Power_Offset - CPICH_RSCP

Where:

 CPICH_RSCP is the received signal code power, the received power on one
code measured on the primary CPICH. It is a measurement performed by the
UE.
 DPCCH_Power_Offset is provided by the RNC to the UE via RRC signaling in
the “Uplink power control info” IE or in the “Uplink power control info short” IE.
These IEs are included in the RRC messages of the radio bearer setup,
reconfiguration and release, transport channel and physical channel
reconfiguration, RRC connection setup and re-establishment and in the
handover to UTRAN command. For Huawei, DPCCH_Power_Offset is calculated
with the following formula:

DPCCH_Power_Offset = PCPICH TRANSMIT POWER + UL interference +
CONSTANT VALUE CONFIGURED BY DEFAULT

Where:

 The PCPICH TRANSMIT POWER parameter defines the PCPICH transmit
power in a cell.
 UL interference is the UL RTWP measured by the NodeB.
 The CONSTANT VALUE CONFIGURED BY DEFAULT parameter reflects the
target Ec/No of the uplink DPCCH preamble.
Parameter name Constant value configured by default

Parameter ID DEFAULTCONSTANTVALUE

GUI range -35–-10


Default value -27

Optional / Optional
Mandatory

MML command SET FRC


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Description:

This parameter is used by the RNC to compute the DPCCH power offset which is
used by the UE to calculate the initial transmit power of UL DPCCH during the
open loop power control process.

1 Maximum Allowed UL Transmit Power

The maximum allowed UL transmit power defines the total maximum output power
allowed for the UE and depends on the desired type of service. The information will
be transmitted on the FACH, mapped on the S-CCPCH, to the UE in the RADIO
BEARER SETUP message of the RRC protocol during the call setup.

For Huawei, the MAX ALLOWED UE UL TX POWER parameter is the maximum
transmit power of the PRACH channel when the UE tries to access to the specified
cell.

Parameter name Max allowed UE UL TX power

Parameter ID MAXALLOWEDULTXPOWER

GUI range -50–33

Physical range& unit dBm

Default value 24

Optional / Optional
Mandatory

MML command ADD CELLSELRESEL; MOD CELLSELRESEL

Description:

The maximum allowed uplink power transmitted on RACH of a UE in the cell,
which is related to the network planning.

If the value of MAX ALLOWED UE UL TX POWER is higher than the UE
capability, the maximum transmission power is of course limited by the UE
capability.

The transmission power on the PRACH for preamble part and message part
cannot be higher than the MAX ALLOWED UE UL TX POWER parameter.


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In addition, there are four parameters (MAX UL TX POWER OF CONVERSATIONAL
SERVICE, MAX UL TX POWER OF STREAMING SERVICE, MAX UL TX POWER
OF INTERACTIVE SERVICE and MAX UL TX POWER OF BACKGROUND
SERVICE) which correspond to the maximum allowed transmit power of four classes
of services: conversational, streaming, interactive and background respectively.

Parameter name Max UL TX power of conversational service

Parameter ID MAXULTXPOWERFORCONV

GUI range -50–33


Default value 24

Optional / Optional
Mandatory

MML command ADD CELLCAC; MOD CELLCAC

Description:

The maximum UL transmit power for conversational service in a specific cell. It is
based on the UL coverage requirement of the conversational service designed by
the network planning.

Parameter name Max UL TX power of streaming service

Parameter ID MAXULTXPOWERFORSTR

GUI range -50–33


Default value 24



Description:

The maximum UL transmit power for streaming service in a specific cell. It is based
on the UL coverage requirement of the streaming service designed by the network
planning.


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Parameter name Max UL TX power of interactive service

Parameter ID MAXULTXPOWERFORINT

GUI range -50–33


Default value 24



Description:

The maximum UL transmit power for interactive service in a specific cell. It is
based on the UL coverage requirement of the interactive service designed by the
network planning.

Parameter name Max UL TX power of background service

Parameter ID MAXULTXPOWERFORBAC

GUI range -50–33


Default value 24



Description:

The maximum UL transmit power for background service in a specific cell. It is
based on the UL coverage requirement of the background service designed by the
network planning.
Recommendation:

The above four parameters define the maximum uplink transmit power when
transmitting the services in a cell.

The bigger these parameters are, the wider the coverage of the corresponding
services will be. When the downlink coverage is exceeded, the uplink coverage
and downlink coverage of the service will become unbalanced. If these parameters
are too small, the uplink coverage will probably be smaller than the downlink
coverage of the service. If there is no special requirement, use the default value.


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2 Rate Matching

The purposes of rate matching are as follows:

 To enable a CCTrCH to multiplex data bits from multiple traffic sub-flows, the
system matches traffic rates to physical channel rates.
 To meet the different QoS requirements of various services, the system adjusts
the coding redundancy degree of each channel.
It is equivalent to changing the bit energy (Eb) of each channel and balancing the
power among different channels. This method improves power usage and
reduces interference. The higher the service QoS requirement is, the higher the
corresponding RMA value. According to the RMA value of each traffic channel,
the rate matching mechanism repeats more bits of the services with higher QoS
requirements. Comparatively, it repeats less, even deletes some bits of the
services with lower QoS requirement. Thus, it meets different QoS requirements
through adjusting the bit redundancy degree of each transport channel.
Parameter name UL rate matching attribute

Parameter ID ULRATEMATCHINGATTR

GUI range 1–256


Default value Values according to SRB and RAB


MML command ADD TYPSRBSEMISTATICTF/

MOD TYPSRBSEMISTATICTF/

ADD TYPRABSEMISTATICTF/

MOD TYPRABSEMISTATICTF/
Description:

Rate matching attribute (RMA) is a semi-static parameter provided by the upper
layer for each traffic channel according to QoS. It represents the weight of
processing (repeating or deleting) data bits on the corresponding transport channel
during rate matching. This parameter is valid in the case of multiplexing of
transport channel, that is, when multiple transport channels are combined into a
CCTrCH. It is used to compare with the RMA values of other multiplexing transport
channels.


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Parameter name DL rate matching attribute

Parameter ID DLRATEMATCHINGATTR

GUI range 1–256



Mandatory

MML command ADD TYPSRBSEMISTATICTF/

MOD TYPSRBSEMISTATICTF/

ADD TYPRABSEMISTATICTF/

MOD TYPRABSEMISTATICTF/
Description:

Rate matching attribute (RMA) is a semi-static parameter provided by the upper
layer for each traffic channel according to QoS. It represents the weight of
processing (repeating or deleting) data bits on the corresponding transport channel
during rate matching. This parameter is valid in the case of multiplexing of
transport channel, that is, when multiple transport channels are combined into a
CCTrCH. It is used to compare with the RMA values of other multiplexing transport
channels.

Rate matching attribute parameters are defined per RAB in the following table:

Typical Services ULRATEMATCHI DLRATEMATCHI
NGATTR NGATTR

CS Domain RAB

12.2bps AMR 137:130:161 137:130:161

64kbps Conversational / Unknown 110 110



28.8kbps Conversational / Unknown 100 100

57.6kbps Streaming 100 100


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Typical Services ULRATEMATCHI DLRATEMATCHI
NGATTR NGATTR

PS Domain RAB





256kbps Streaming 100 100







384kbps Background 100 100







8 kbps Background 140 140

384kbps Interactive 100 100







8 kbps Interactive 140 140

Signaling RB

3.4kbps SRB 180 180

13.6kbps SRB 180 180


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3 Power Difference Between DPCCH And DPDCH

The uplink DPCCH and DPDCH(s) are transmitted on different codes. In order to
meet a given QoS requirement on the transport channels whatever the transport
format they use, various power differences between DPDCH and DPCCH are defined
through gain factors, called βc for DPCCH and βd for DPDCH.

There are two ways of controlling the gain factors of the DPCCH code and the
DPDCH codes for different TFCs in normal (non-compressed) frames:

− βc and βd are signalled for the TFC, or

− βc and βd is computed for the TFC, based on the signalled settings for a
reference TFC.

3GPP allows combinations of these two methods to be used to associate βc and βd
values with all TFCs in the TFCS. These two methods are described in subsections
5.1.2.5.2 and 5.1.2.5.3 respectively of TS25.214. Several reference TFCs may be
signaled from higher layers.

For Huawei, a mix of these techniques is effectively applied, which requires the RNC
to compute and signal all TFC offsets when required. The RNC computes a new
power offset for each required TFC dynamically using a single set of configurable
reference values (corresponding to parameters Reference BetaC and Reference
BetaD) stored for each pre-defined RABs or SRBs. This computed TFC specific offset
is then signaled to the UE.

Parameter name Reference BetaC

Parameter ID BETAC

GUI range 1–15




MML command ADD TYPSRBBASIC/MOD TYPSRB/ADD
TYPRABBASIC/MOD TYPRAB

Description:

Power occupation ratio of the control part of reference TFC.


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Parameter name Reference BetaD

Parameter ID BETAD

GUI range 1–15




MML command ADD TYPSRBBASIC/MOD TYPSRB/ADD
TYPRABBASIC/ MOD TYPRAB

Description:

Power occupation ratio of the data part of reference TFC.

UL reference power offset parameters (βc,ref and βd,ref) are defined in the following
table:

Typical Services β c,ref : β d,ref
CS Domain RAB

12.2bps AMR 12:15

64kbps Conversational / Unknown 6:15



28.8kbps Conversational / Unknown 13:15

57.6kbps Streaming 7:15

PS Domain RAB





256kbps Streaming 4:15





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Typical Services β c,ref : β d,ref



384kbps Background 4:15







8 kbps Background 15:11
384kbps Interactive 4:15







8 kbps Interactive 15:11

Signaling RB

3.4kbps SRB 15:12

13.6kbps SRB 12:15

Either Reference BetaC or Reference BetaD must be set to 15 for each instance
of UL reference power offset.

The gain factors (βc and βd) are computed for certain TFCs, based on the settings for
a reference TFC with the formula defined in subsection 5.1.2.5.3 of TS25.214.

In Huawei implementation, in the case of RAB combination, the radio bearer specific


30

reference values to be used are those belonging to the radio bearer whose maximum
rate TF has the highest bit rate of the radio bearers being combined. For example, for
the combination of the 3.4 kbps SRB service, 384 kbps background service, and 12.2
kbps AMR service, the reference power offset values applied are those belonging to
the maximum rate TF (12x336) of 384 kbps background radio bearer.

4 First Radio Link Establishment

When commanded by higher layers, the TPC commands sent on a downlink radio link
from NodeBs that have not yet achieved uplink synchronization will follow a pattern as
follows:

If the radio link is part of the first radio link set sent to the UE and if the value "n"
obtained from the parameter DL POWER CONTROL MODE 1 is different from 0,
then:

 The TPC pattern shall consist of n instances of the pair of TPC commands ("0",
"1"), followed by one instance of TPC command "1", where ("0","1") indicates
the TPC commands to be transmitted in two consecutive slots.
 The TPC pattern continuously repeat but shall be forcibly re-started at the
beginning of each frame where CFN mod 4 = 0.

In addition,

 The TPC pattern shall consist of only TPC commands "1".
 The TPC pattern shall terminate when uplink synchronization is achieved.
Parameter name DL power control mode 1

Parameter ID DLTPCPATTERN01COUNT

GUI range 0–30


Default value 10


MML command ADD CELLSETUP/MOD CELLSETUP

Description:

DL transmit power control (TPC) mode of the first radio link set before completion
of UL synchronization.


31

Caution:

In order to change the value of the DL POWER CONTROL MODE 1 parameter
through MOD CELLSETUP, the cell shall be firstly de-activated through DEA CELL.

5 Transmit Power Control in the UL DPCCH Power Control Preamble

An uplink DPCCH Power Control Preamble (PC Preamble) is a period of uplink
DPCCH transmission prior to the start of the uplink DPDCH transmission in order to
ensure that the inner loop power control has converged when the transmission of the
data bits begins. It consists of a given number of DPCCH slots transmitted prior to the
data transmission on DPDCH. The RNC transmits the PC Preamble parameter
(number of DPCCH preamble slots) in the “Uplink DPCH power control info” IE using
the RRC signaling.

In addition to the PC Preamble delay, the mobile will not send any data on signaling
radio bearers during the number of frames indicated in the “SRB delay” IE, sent
through RRC signaling in the “Uplink DPCH power control info” IE.

Considering the application scenarios, different values for PC Preamble and SRB
delay parameters are configured.

 In the case of RRC connection establishment, PC Preamble and SRB delay are
respectively defined by parameters RRC PROC DPDCH PC PREAMBLE
LENGTH and RRC PROC SRB DELAY.
 In the case of hard handover, PC Preamble and SRB delay are respectively
defined by parameters HHO PROC DPDCH PC PREAMBLE LENGTH and
HHO PROC SRB DELAY.


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Parameter name RRC Proc DPDCH PC preamble length

Parameter ID RRCPROCPCPREAMBLE

GUI range 0–7

Physical range& unit Frame

Default value 0


MML command ADD CELLCAC/MOD CELLCAC

Description:

DPDCH power control preamble length in DCH RRC process.

Parameter name RRC Proc SRB delay

Parameter ID RRCPROCSRBDELAY

GUI range 0–7


Default value 7



Description:

Delay of SRB in DCH RRC process.


33

Parameter name HHO Proc DPDCH PC preamble length

Parameter ID HHOPROCPCPREAMBLE

GUI range 0–7


Default value 0



Description:

DPDCH power control preamble length in DCH HHO process.

Parameter name HHO Proc SRB delay

Parameter ID HHOPROCSRBDELAY

GUI range 0–7

Physical range& unit Frame.

Default value 7



Description:

Delay of SRB in DCH HHO process.

Inner loop power control is thus applied on the DPCCH only, in a first time, starting
from the initial DPCCH transmit power determined by the open loop power control
process. Then, once PC Preamble DPCCH slots have been transmitted and SRB
delay slots passed, data starts to be transmitted on the DPDCH at an initial transmit
power deduced from the current DPCCH transmit power and DPDCH/DPCCH power
difference (using βc and βd gain factors).

II. Downlink Open-Loop Power Control

1) Downlink Open-Loop Power Control on Common Channel

For the common channels, DL open-loop power control is to determine how much


34

power is allocated to the PCPICH, P-SCH, S-SCH, P-CCPCH, S-CCPCH, AICH, and
PICH channels.

As mentioned previously, the P-CPICH power is defined by the PCPICH TRANSMIT
POWER parameter as an absolute value in dBm. The power of all other common
channels is defined in relation with the PCPICH TRANSMIT POWER parameter.

The following tables describe which parameter is used to determine the power for
each common channel:

Parameter name PSCH transmit power

Parameter ID PSCHPOWER


Physical range& unit -35–15, step: 0.1 (dB)

Default value -50


MML command ADD PSCH/MOD CELL

Description:

The offset of the PSCH transmit power from the PCPICH transmit power in a cell.

Parameter name SSCH transmit power

Parameter ID SSCHPOWER


Physical range& unit -35–15, step: 0.1(dB)

Default value -50


MML command ADD SSCH/MOD CELL

Description:

The offset of the SSCH transmit power from the PCPICH transmit power in a cell


35

Recommendation:

These two parameters (PSCH TRANSMIT POWER and SSCH TRANSMIT
POWER) can be adjusted through measurement in the actual environment so that
the transmit powers of the synchronization channels just satisfy the UE receiving
demodulation requirement. Specifically, when UEs receive signals at different
locations within the range of the cell, the transmit power should be just enough to
ensure that the UE can implement fast synchronization in most areas at the verge
of the cell. Neither P-SCH nor S-SCH has come through channel code spectrum
spread, so they produce more serious interference than other channels do,
especially for near–end users. Therefore, the value should not be too big.

Parameter name BCH transmit power

Parameter ID BCHPOWER


Default value -20


MML command ADD BCH/MOD CELL

Description:

The offset of the BCH transmit power from the PCPICH transmit power in a cell.

Recommendation:

The BCH TRANSMIT POWER parameter can be adjusted and optimized through
measurement in the actual environment. When UEs receive signals at different
locations within the range of the cell, the transmit power should be just enough to
ensure the correct demodulation of the information carried on the channel in most
areas at the verge of the cell. This setting of this parameter should not be too big,
so as to avoid unnecessary waste of the transmit power.

If the setting of this parameter is too small, the user at the verge of the cell will fail
to receive the system information correctly, and the downlink common channel
coverage will be influenced, which will affect cell coverage; if the setting is too big,
other channels will be interfered, the power resources will be occupied, and
consequently the cell capacity will be influenced.


36

Parameter name Max transmit power of FACH

Parameter ID MAXFACHPOWER



Default value 10

Optional / Optional
Mandatory

MML command ADD FACH/MOD SCCPCH

Description:

The offset between the FACH transmit power and PCPICH transmit power in a
cell.

Recommendation:

Set the maximum FACH transmit power to an appropriate value that is just enough
to ensure the target BLER.

If the setting of this parameter is too small, the UE at the cell verge will fail to
receive correctly the services and signaling borne over the FACH, resulting in
influence on the downlink common channel coverage and the cell coverage; if it is
too big, other channels will be interfered, the power resources will be occupied,
and consequently the cell capacity will be influenced.

Caution:

In order to change the value of the MAX TRANSMIT POWER OF FACH parameter if
the current cell is on-going and there is one and only one SCCPCH in this cell, or in
order to change the configuration of the SCCPCH with the smaller SCCPCH ID when
there are two SCCPCHs in this cell, the cell shall be firstly de-activated through DEA
CELL.


37

Parameter name PCH power

Parameter ID PCHPOWER



Default value -20


MML command ADD PCH/MOD SCCPCH

Description:

The offset between the PCH transmit power and PCPICH transmit power in a cell.

Recommendation:

The default value of the PCH POWER parameter is -20, namely -2 dB.

If this parameter is too small, the UE at the cell verge will fail to receive paging
messages correctly, and this will influence downlink common channel coverage
and cell coverage; if it is too big, other channels will be interfered, the downlink
transmit power will be occupied, and consequently the cell capacity will be
influenced.

Parameter name AICH power offset

Parameter ID AICHPOWEROFFSET

GUI range -22–5


Default value -6


MML command ADD CHPWROFFSET/MOD AICHPWROFFSET

Description:

The difference between the transmit power of AICH and that of PCPICH.


38

Recommendation:

The default value of the AICH POWER OFFSET parameter is -6, namely -6 dB.

An appropriate transmit power value should be set for AICH to ensure that all
users at cell verge can receive the access indication. However, to avoid waste of
the power, the setting of the transmit power should not be too big.

Parameter name PICH power offset

Parameter ID PICHPOWEROFFSET

GUI range -10–5


Default value -7


MML command ADD CHPWROFFSET/MOD
PICHPWROFFSET

Description:

The difference between the transmit power of PICH and that of PCPICH.

Recommendation:

The default value of the PICH POWER OFFSET parameter is -7, namely -7 dB.

If this parameter is too small, the UE at the cell verge will fail to receive paging
messages correctly, which will probably result in mis–operation in reading PCH
channel and waste of the UE battery and affect the downlink common channel
coverage and the cell coverage; if it is too big, other channels will be interfered, the
power resources will be occupied, and consequently the cell capacity will be
influenced.

2) Downlink Open-Loop Power Control on Dedicated Channel (DPDCH)

The aim of the DL open-loop power control on DPDCH is to determine the transmit
power of the traffic (dedicated) channel based on the downlink measurement report of
the UE. Both UE and UTRAN shall take part in downlink open-loop power control on
the DPDCH, as shown in 2.


39

DCH

RACH reports the measured value

Measure CPICH Ec/N0
Determine the downlink initial power control

Figure 1.12Downlink open-loop power control on the DPDCH

The following gives a formula to calculate the initial power of the DPDCH when a
traffic (dedicated) channel is set up:

 
R Eb  P 
Pinitial = × ( ) DL ×  CPICH
− αPTotal 
W N0  Ec 
 ( ) CPICH 
 N0 

Where:

 R is the requested data bit rate by the user.
 W is the chip rate.

(Eb / N0) DL is the Eb/No target to ensure the service quality. In Huawei

implementation, RNC searches for a value of Eb/No target dynamically using a
set of pre-defined values corresponding to the specific cell environment type,
code type, coding rate and BLER target. For detailed information, refer to the
Load Control.
 (Ec/N0)CPICH is the ratio of received energy per chip to noise spectral density of
CPICH received by UE.
 α is the orthogonality factor in the downlink. In the WCDMA system, orthogonal
codes are employed in the downlink to separate the users, and without any multi-
path propagation on the orthogonality remains when the Node B signal is
received by the mobile station. However, if there is sufficient delay spread in the
radio channel, part of the base station signals will be regarded as multiple
access interference by the mobile station. The orthogonality of 1 corresponds to
perfectly orthogonal users.


40

 Note:

 In Huawei implementation, α in the above formula is set to 0.
 Ptotal is the carrier power measured at the NodeB and reported to the RNC.

1 Radio Link Reconfiguration Power Setting

When reconfiguring a radio link, the new physical channel may not have the same
power as the previous one (because of different SF, and so on). It is not specified,
however, in 3GPP protocol that the RNC can send a new initial power for the new
configuration in the RADIO_LINK_RECONFIGURATION_PREPARE message, which
provides the NodeBs with the new physical/transport channel configuration.

Thus, the NodeB will adjust the downlink power through the process of inner-loop
power control.

2 Initial Power Setting In Soft Handover

In order to prevent a waste of downlink power while adding a new leg in the active
set, a new adjustment for power of the new leg is used. Based on the above
calculation as used for the initial power of the DPDCH when a traffic (dedicated)
channel is set up, the power required by a new leg introduced in the active set shall
be decreased by an offset, which is defined by the INITIAL POWER OFFSET FOR
SHO parameter.

Parameter name Initial power offset for SHO

Parameter ID SHOINITPWRPO

GUI range 0–25


Default value 15



Description:

Initial DL power offset for a new added RL in SRNC.


41

3 Upper and Lower Limits of DL DPDCH Power

The downlink dedicated traffic channel is limited by an upper and lower limit for each
radio link. This limitation is set through the RL MAX DL TX POWER and RL MIN DL
TX POWER parameters. Both parameters are provided a value for the different data
rate of radio access bearers. So they correspond to a set of values rather than a
single value.

Parameter name RL Max DL TX power

Parameter ID RLMAXDLPWR


Physical range& unit -35–15; step: 0.1(dB)

Default value Values according to data rate of RABs


MML command ADD CELLRLPWR/MOD CELLRLPWR

Description:

The maximum downlink transmit power of radio link. This parameter should fulfill
the coverage requirement of the network planning, and the value is relative to
PCPICH transmit power.

Parameter name RL Min DL TX power

Parameter ID RLMINDLPWR


Physical range& unit -35–15; step: 0.1(dB)

Default value Values according to data rate of RABs


MML command ADD CELLRLPWR/MOD CELLRLPWR

Description:

The minimum downlink transmit power of radio link. This parameter should
consider the maximum downlink transmit power and the dynamic range of power
control, and the value is relative to PCPICH transmit power.


42

The parameters RL MAX DL TX POWER and RL MIN DL TX POWER must verify
the following relationship:

RL MIN DL TX POWER ≤RL MAX DL TX POWER

Typical Services RL MAX DL TX POWER RL MIN DL TX POWER

CS Domain RAB

12.2bps -30 -180

28.8kbps -20 -170

32kbps -20 -170

57.6kbps -10 -160

64kbps 30 -120

PS Domain RAB

384kbps 40 -110

256kbps 20 -170

144kbps 0 -150

128kbps 0 -150

64kbps -20 -170

32kbps -40 -190

16kbps -60 -210

8kbps -80 -230

4 Power Difference between DPCCH and DPDCH

For the downlink DPCH, the relative transmit power offset between DPCCH fields and
DPDCHs is determined by the network. The TFCI, TPC and pilot fields of the DPCCH
are offsets related to the power of DPDCHs by PO1, PO2, and PO3 dB respectively.
The power offsets PO1, PO2 and PO3 are defined by the TFCI POWER OFFSET,
TPC POWER OFFSET, and PILOT POWER OFFSET parameters respectively.

These power offsets cannot be reconfigured during the connection. These offsets are


43

radio link specific, which are identical for all TFC in the TFCS, whereas for the uplink
the gain factors are TFC-dependent.

Parameter name TFCI power offset

Parameter ID TFCIPO

GUI range 0–24

Physical range& unit 0–6; step: 0.25(dB)

Default value 0

Optional / Optional
Mandatory

MML command SET FRC

Description:

The offset of TFCI bit transmit power from data bit transmit power in each time slot
of radio frames on DL DPCH.

Parameter name TPC power offset

Parameter ID TPCPO

GUI range 0–24


Default value 12


MML command SET FRC

Description:

The offset of TPC bit transmit power from data bit transmit power in each time slot


44

Parameter name Pilot power offset

Parameter ID PILOTPO

GUI range 0–24


Default value 12


MML command SET FRC

Description:

The offset of pilot bit transmit power from data bit transmit power in each time slot

The downlink transmit power control procedure controls simultaneously the power of
a DPCCH and its corresponding DPDCHs. The power control loop adjusts the power
of the DPCCH and DPDCHs with the same amount, that is to say, the relative power
difference between the DPCCH and the DPDCHs is not changed.

1.6.3 Inner-Loop Power Control

Inner-loop power control is also called fast closed-loop power control. It controls the
transmit power according to the information returned from the peer physical layer. The
UE and the NodeB can adjust the transmit power according to the RX SIR of the peer
end, to compensate the fading of radio links.

Inner-loop power control consists of uplink inner-loop power control and downlink
inner-loop power control, and they work separately.

I. Uplink Inner-Loop Power Control

Uplink inner-loop power control is used to control the power of the uplink radio links.
In fact, uplink inner-loop power control is executed on the DPCCH, and related
DPDCH transmit power is calculated from DPCCH transmit power according to
DPDCH/DPCCH power ratio (βd /βc). For details, refer to 1.6.2“Open-Loop Power
Control”.

The RNC sends the SIR target to the NodeB and then the NodeB compares the
estimated SIR with the SIR target of uplink DPCCH pilot symbol once every timeslot.


45

 If the estimated SIR is greater than the SIR target, the NodeB sends a TPC
command “down” to the UE on the downlink DPCCH TPC field.
 Otherwise, the NodeB sends a TPC command "Up".

 Note:

 The "Up" command means TPC = 1 and the "Down" command means TPC = 0.

For the SIR = RSCP / ISCP * SF ,

 The Received Signal Code Power (RSCP) is unbiased measurement of the
received power on one code.
 The Interference Signal Code Power (ISCP) is the interference on the received
signal, and SF=the spreading factor used on the DPCCH.

SIR estimation and
compare with SIR target TPC

1500 Hz
SIR target

NodeB UE

Figure 1.13Uplink inner-loop power control

The following describes the uplink inner-loop power control:

1 Single Radio Link

It means that the UE will receive only one TPC in each slot. The NodeB will estimate
the SIR value and sends TPC to the UE according to the comparison between SIR
target and SIR estimated result.

If the estimated SIR is greater than the SIR target, the NodeB sends a TPC command
“down” to the UE on the downlink DPCCH TPC field. Otherwise, the NodeB sends a


46

TPC command “up”, where the “up” command means TPC = 1 and the “down”
command means TPC = 0.

When the UE receives the TPC, UE will adjust uplink transmit power according to the
Power Control Algorithm (PCA).

There are two types of inner-loop PCA algorithm: PCA1 and PCA2. The RNC
configures the PCA algorithm based on the POWER CONTROL ALGORITHM
SELECTION parameter.

Parameter name Power control algorithm selection

Parameter ID PWRCTRLALG

GUI range ALGORITHM1, ALGORITHM2.


Default value ALGORITHM1


MML command SET FRC

Description:

This parameter is used to inform the UE of the method for translating the received
Transmit Power Control (TPC) commands. In other words, it is used to select UL
power control algorithm.


Huawei sets the POWER CONTROL ALGORITHM SELECTION parameter to
algorithm1 as default value for all power control configurations

PCA1: UE adjusts uplink transmit power for each slot; the step of PCA1 should be
1dB or 2dB by UL CLOSED LOOP POWER CONTROL STEP SIZE parameter.


47

Parameter name UL closed loop power control step size

Parameter ID ULTPCSTEPSIZE

GUI range 1–2


Default value 1


MML command SET FRC

Description:

The step size of the closed loop power control performed on UL DPCCH. This
parameter is mandatory when the parameter [Power control algorithm selection] is
set as "ALGORITHM1".

The following table lists the TPC command corresponding to the specific TPC at
PCA1 algorithm:

TPC TPC_cmd

0 -1

1 1

PCA2: The UE adjusts the uplink transmit power for each 5-slot cycle and the step is
1 dB fixedly.

The following table lists the TPC command corresponding to the specific TPC at
PCA2 algorithm:

TPC TPC_cmd

0,0,0,0,0 0,0,0,0,-1

1,1,1,1,1 0,0,0,0,1

Else 0,0,0,0,0

2 Softer Handover


48

It means that the UE will receive more than one TPC in each slot, but all the TPCs are
the same from each cell which belongs to one NodeB.

The UE will combine the DL TPC by Maximum Ratio Combining (MRC) algorithm.
Therefore, other processing is the same as that in scenario1 (single radio link).

3 Soft handover

It means that the UE will receive more than one TPC in each slot, and all the TPCs
come from different NodeBs.

On the NodeB side, there are two phases to process power control during the soft
handover procedure:

 Uplink synchronization phase:

The NodeB should send durative TPC=1 to newly-added radio link before
successful synchronization.

 Multi-radio link phase:

Each NodeB and each cell will estimate the SIR
individually and the general TPC individually. Therefore,
the UE may receive different TPC from different RLS.

On the UE side, the UE will receive different TPCs from different RLS at the same
time. Therefore, the UE should combine all the TPCs which come from different
NodeBs to get TPC commands and adjust uplink transmit power according to the
combined TPC commands.

There is different UE TPC combination algorithm for PCA1 and PCA2.

 In case of PCA1

First, the UE shall conduct a soft symbol decision Wi on each of the power control
commands TPCi, where i = 1, 2, …, N (N is greater than 1 and is the number of TPC
commands from radio links of different radio link sets.) That may be the result of a first
phase of combination.

Finally, the UE derives a combined TPC command, TPC_cmd, as a function γ of all
the N soft symbol decisions Wi:


49

- TPC_cmd = γ (W1, W2, … WN), where TPC_cmd can take the values 1 or -1.

The function γ shall fulfill the following criteria:

If the N TPCi commands are random and uncorrelated, with equal probability of being
transmitted as "0" or "1", the probability that the output of γ is equal to 1 shall be
greater than or equal to 1/(2N), and the probability that the output of γ is equal to -1
shall be greater than or equal to 0.5. Further, the output of γ shall equal 1 if the TPC
commands from all the radio link sets are reliably “1”, and the output of γ shall equal
-1 if a TPC command from any of the radio link sets is reliably “0”.

Then, after deriving a combined TPC_cmd, the UE will adjust uplink transmit power
as pre-defined power step which is configured by the RNC.

 In case of PCA2

The UE shall make a hard decision on the value of each TPCi, where i = 1, 2, …, N (N
is the number of TPC commands from radio links of different radio link sets.) That
may be the result of a first phase of combination.

The UE shall follow this procedure for 5 consecutive slots, resulting in N hard
decisions for each of the 5 slots. The sets of 5 slots shall be aligned to the frame
boundaries and there shall be no overlap between each set of 5 slots.

The value of TPC_cmd is zero for the first 4 slots. After 5 slots have elapsed, the UE
shall determine the value of TPC_cmd for the fifth slot in the following way:

The UE first determines one temporary TPC command, TPC_temp i, for each of the N
sets of 5 TPC commands as follows:

- If all 5 hard decisions within a set are "1", TPC_tempi = 1.

- If all 5 hard decisions within a set are "0", TPC_tempi = -1.

- Otherwise, TPC_tempi = 0.

Finally, the UE derives a combined TPC command for the fifth slot, TPC_cmd, as a
function γ of all N temporary power control commands TPC_tempi:

TPC_cmd (5th slot) = γ (TPC_temp1, TPC_temp2, …, TPC_tempN), where TPC_cmd
(5th slot) can take the values 1, 0 or –1, and γ is given by the following definition:


50

TPC_cmd is set to -1 if any of TPC_temp1 to TPC_tempN are equal to -1.

N
1
Otherwise, TPC_cmd is set to 1 if
N
∑ TPC _ temp
i =1
i > 0.5 .

Otherwise, TPC_cmd is set to 0.

Then, after deriving a combined TPC_cmd, the UE will adjust uplink transmit power
as 1dB step.

I. Downlink Inner-Loop Power Control

Downlink inner-loop power control is used to control the power of the downlink DPCH.

The UE receives the SIR target from higher layers, estimates the downlink SIR from
the pilot symbols of the downlink DPCH, and compares this estimated SIR with the
SIR target.

 If the estimated SIR is greater than the SIR target, the UE sends a TPC
command "down" to the NodeB.
 Otherwise, the UE sends a TPC command “up”.

TPC
SIR estimation and
compare with SIR target

1500 Hz

SIR target

NodeB UE

Figure 1.14Downlink inner-loop power control

The following describes the downlink inner-loop power control:

1 Single Radio Link

The downlink power control can be classified into two modes.


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The UE shall check the downlink power control mode (DPC_MODE) before the TPC
command is generated:

 If DPC_MODE = 0,

The UE sends a unique TPC command in each slot and the TPC command
generated is transmitted in the first available TPC field in the uplink DPCCH.

 If DPC_MODE = 1,

The UE repeats the same TPC command over 3 slots and the new TPC
command is transmitted such that there is a new command at the beginning of
the frame.

The DPC_MODE parameter is a UE-specific parameter controlled by the UTRAN.
The DPC mode can be set by the DL POWER CONTROL MODE parameter.

Parameter name DL power control mode

Parameter ID DPCMODE

GUI range SINGLE_TPC, TPC_TRIPLET_IN_SOFT,
TPC_AUTO_ADJUST.


Default value SINGLE_TPC


MML command SET FRC
Description:

SIGNLE_TPC, a fast power control mode, indicates that a unique TPC command
is sent in each time slot on DPCCH. TPC_TRIPLET_IN_SOFT, a slow power
control mode, indicates that the same TPC command is sent in three time slots, it
is applicable to soft handover and it can decrease the power deviation.
TPC_AUTO_ADJUST, an automatically adjusted mode, indicates that the value of
DPC_MODE can be modified by sending the message "ACTIVE SET UPDATE" to
UE.


Huawei sets the DL POWER CONTROL MODE parameter to singel_TPC as
default value for all power control configurations


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Upon receiving the TPC commands, the UTRAN shall adjust its downlink
DPCCH/DPDCH power accordingly.

 If DPC_MODE = 0, the UTRAN shall estimate the transmitted TPC command
TPCest to be 0 or 1, and shall update the power every slot.
 If DPC_MODE = 1, the UTRAN shall estimate the transmitted TPC command
TPCest over three slots to be 0 or 1, and shall update the power every three slots.

After estimating the k:th TPC command, the UTRAN shall adjust the current downlink
power P(k-1) [dB] to a new power P(k) [dB] according to the following formula:

P(k) = P(k - 1) + PTPC(k) + Pbal(k)

Where:

 PTPC(k) is the k:th power adjustment due to the inner loop power control.
 Pbal(k) [dB] is a correction according to the downlink power control procedure for
balancing radio link powers towards a common reference power. For a single
radio link, Pbal equals 0.
 PTPC(k) is calculated according to the following:

– If the value of Limited Power Increase Used parameter is 'Not used', then,

+ Δ if TPC est ( k ) = 1
PTPC (k ) =  TPC , [dB]
− Δ TPC if TPC est (k ) = 0

The limited power increase used parameter could be set by the parameter of
INNER_LOOP_DL_LMTED_PWR_INC_SWITCH.


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Parameter name Power control algorithm switch

Parameter ID INNER_LOOP_DL_LMTED_PWR_INC_SWITCH

GUI range 1(ON), 0(OFF)


Default value 0


MML command SET CORRMALGOSWITCH

Description:

When it is checked, limited power increase algorithm is applied in the inner loop
power control.

– If the value of limited power increase used parameter is 'Used', then, the k:th
inner loop power adjustment shall be calculated through the following formula:

+ ∆ TPC if TPC est (k ) = 1 and ∆ sum (k ) + ∆ TPC < Power_Raise_Limit

PTPC (k ) =  0 if TPC est (k ) = 1 and ∆ sum (k ) + ∆ TPC ≥ Power_Raise_Limit , [dB]
− ∆ if TPC est ( k ) = 0
 TPC

The Power_Raise_Limit can be set by the POWER INCREASE LIMIT parameter.

Parameter name Power increase limit

Parameter ID POWERRAISELIMIT

GUI range 0–10


Default value 10



Description:

The increase of DL transmit power within DlPowerAverageWindowSize cannot
exceed this parameter value.


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Caution:

In order to change the value of the POWER INCREASE LIMIT parameter through
MOD CELLSETUP, the cell shall be firstly de-activated through DEA CELL.

Where:

k−1
∆ (k ) =
sum
i= −
∑PTPC (i )
k DL_Power_Averaging_Window_Size

is the temporary sum of the last DL_Power_Averaging_Window_Size inner loop
power adjustments (in dB). DL_Power_Averaging_Window_Size can be set by the
DL POWER WINDOW AVERAGE SIZE parameter.

Parameter name DL power window average size

Parameter ID DLPOWERAVERAGEWINDOWSIZE

GUI range 1–60

Physical range& unit slot.

Default value 20



Description:

Content: UTRAN calculates the increase of DL transmit power within the period
defined via this parameter to determine whether the increase exceeds
PowerRaiseLimit. If so, UTRAN will not increase the power even when it receives
the command to raise the power.


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Caution:

In order to change the value of the DL POWER WINDOW AVERAGE SIZE
parameter through MOD CELLSETUP, the cell shall be firstly de-activated through
DEA CELL.

The power control step size TPC can be any of the four values of 0.5, 1, 1.5 and 2 dB
and be set by the FDD DL POWER CONTROL STEP parameter.

Parameter name FDD DL power control step size

Parameter ID FDDTPCDLSTEPSIZE

GUI range STEPSIZE_0.5DB, STEPSIZE_1DB, STEPSIZE_1.5DB,
STEPSIZE_2DB.

Physical range& unit 0.5, 1, 1.5, 2(dB)

Default value STEPSIZE_1DB


MML command SET FRC

Description:

Content: The step size of the closed loop power control performed on DL DPCH in
Frequency Division Duplex (FDD) mode.

2 Scenario Softer Handover

In the case of softer handover, the NodeB gets one TPC after MRC combination.
Then the downlink power procedure is the same as that in single radio link.

3 Soft Handover

For details about the soft handover, refer to the description in the subsection
1.6.5“Downlink Power Balance”.

1.6.4 Outer-Loop Power Control

The aim of outer-loop power control is to maintain the communication quality at the


56

level required by the service bearer through adjustment of the SIR target. This control
acts on each DCH belonging to the same RRC connection.

The SIR target needs to be adjusted when the UE speed or the multi-path
propagation environment changes, so that the communication quality can maintain
the same. If a fixed SIR target is selected, the resulting quality of the communication
might be too low or too high, which may cause an unnecessary power rise in most
situations.

I. Uplink Outer-Loop Power Control

The uplink quality is observed after macro diversity selection combining in the RNC.
Therefore, uplink outer-loop power control is performed in the SRNC.

The SRNC compares the RX BLER with the BLER target. If the RX BLER is greater
than the BLER target, the SRNC increases the SIR target; otherwise, decreases.

After adjusting the SIR target, the SRNC sends the new SIR target through FP frames
to all NodeBs for uplink inner loop power control.

BLER SIR measurement
measurement and comparing
and comparing

Outer loop Inner loop
BLER target
settting SIR target settting Sent TPC
UE
RNC
NodeB

Figure 1.15Uplink outer-loop power control procedure

The uplink outer-loop power control for all UEs can be deactivated by
OLPC_SWITCH; or by setting SIR ADJUSTMENT STEP to zero to deactivate uplink
outer loop power control for different services.


57

Parameter name Power control algorithm switch

Parameter ID OLPC_SWITCH

GUI range 0, 1.

Physical range& unit OFF, ON (NONE)

Default value 1


MML command SET CORRMALGOSWITCH

Description:

When it is ON, RNC will update the uplink SIR TARGET of RLs on the NODEB
side by IUB DCH FP signals.

1 Initial SIR Target Setting

The initial SIR target value is provided by the RNC to the NodeB through the SIR INIT
TARGET VALUE parameter which is service-dependent. This value is transmitted to
the NodeB using NBAP signaling at each RADIO LINK SETUP or RADIO LINK
RECONFIGURATION PREPARE.

Parameter name SIR init target value

Parameter ID INITSIRTARGET

GUI range 0–255

Physical range& unit -8.2–17.3; step: 0.1(dB)

Default value Refer to I.


MML command ADD TYPSRBOLPC/MOD TYPSRBOLPC/ ADD
TYPRABOLPC/MOD TYPRABOLPC

Description:

This parameter defines the initial SIR target value of Outer Loop Power Control
algorithm. Value 0 corresponds to -8.2 dB, value 10 to -7.2 dB, and value 255 to
17.3 dB.



58

For the same SRB or TRB, SIR INIT TARGET VALUE, MAXIMUM SIR TARGET
and MINIMUM SIR TARGET must verify the following relationship:

MINIMUM SIR TARGET ≤ SIR INIT TARGET VALUE ≤MAXIMUM SIR TARGET

2 SIR Target Adjustment

The outer-loop power control adjusts SIR target through a OLPC ADJUSTMENT
PERIOD parameter as follows:

BLERmeas ((n − 1), i ) − BLERtar (i )
SIRtar(n)＝MAX [ SIRtar (n − 1) + * Step(i ) * factor ]
BLERtar (i )

In the above formula, meanings of the parameters are as follows:

 i is the ith transmission channel.
 n is the nth adjustment period.
 SIRtar(n) is the SIR target used by the nth adjustment period which could be set
by parameter OLPC ADJUSTMENT PERIOD.
 MAX is the maximum value in the total i transmission channels.
 ErrTb( n，i)
BLERmeas(n,i) is the instantaneous BLER meas (n, i )＝ Tb(n，i) measured for the

ith transmission channel in the nth adjustment period.

- Tb(n,i) is the number of error blocks in the TBs received from the ith
transmission channel in the nth adjustment period.

- ErrTb(n,i) is the number of error blocks indicated by the CRCI in the Tb(n,i) that
is received from the ith transmission channel.

 BLERtar(i) is the BLER target of the ith transmission channel, which could be
set by parameter SERVICE DCH_BLER TARGET VALUE.
 Step(i) is the adjustment step of the ith transmission channel, which could be set
by parameter SIR ADJUSTMENT STEP.
 factor is the adjustment factor which could be set by parameter SIR
ADJUSTMENT COEFFICIENT.


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Parameter name OLPC adjustment period

Parameter ID SIRADJUSTPERIOD

GUI range 1–100

Physical range& unit 10–1000, step: 10(ms)

Default value Refer to I.

Mandatory

MML command ADD TYPSRBOLPC/MOD TYPSRBOLPC/ ADD
TYPRABOLPC/MOD TYPRABOLPC

Description:

Outer Loop Power Control varies with radio environment. A fast changing radio
environment leads to a shorter Outer Loop Power Control adjustment period, while
a slower changing one makes the period longer.

Parameter name SIR measurement filter coefficient

Parameter ID SIRMEASFILTERCOEF

GUI range D0, D1, D2, D3, D4, D5, D6, D7, D8, D9, D11, D13, D15,
D17, D19.

Physical range& unit 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 13, 15, 17, 19(NONE)

Default value D0


MML command SET OLPC

Description:

The filter coefficient used for SIR measurement.


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