Introduction to the RAN14.0 Feature–Voice Experience Improvement for Weak Reception UEs V0.4

8/10/2019 Introduction to the RAN14.0 Feature–Voice Experience Improvement for Weak Reception UEs V0.4

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Introduction to the RAN14.0

Feature

Voice Experience Improvement

for Weak Reception UEsWireless Product Rollout Department



Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page 2

About This Course

This course is based on the radio access network (RAN)

14.0 version. Before you learn this course, ensure that you

have completed the following courses based on the xxx

version: ×××




Objectives

After completing this course, you will be able to:

Be familiar with values and application scenarios of the Voice

Experience Improvement for Weak Reception UEs feature.

Explain the basic theory of the Voice Experience Improvement

for Weak Reception UEs feature.

Enable and verify the Voice Experience Improvement for Weak

Reception UEs feature based on manuals.




Contents

1 Feature Descrip tion

2 Feature Planning

3 Feature Deployment

4 Performance Optimization

5 O&M and Troubleshooting

6 Reference Document and Acronyms & Abbreviations




Locked

network long

call

Dual-mode

long call

Dual-mode

short call

Number of call drops

Page 5

Feature Description

On a live UMTS network, some phone models underperform when compared with other vendor phones

in the same radio environment:Poor signal reception leads to downlink signaling radio bearer (SRB) failures.

The special antenna design leads to deteriorated signal reception when a user is holding the unit.

Therefore, these phone models are more prone to call drops. However, these phone models are

generally used by high Average Revenue Per User (APRU) users. To preferentially improve user

experience, Huawei introduces the Voice Experience Improvement for Weak Reception UEs feature.

Number of Call drops for normal

reception UEs

The call drop rate of weak

reception UEs is above average.




Basic Procedure

This feature enables the radio network controller (RNC) to identify weak

reception UEs based on the International Mobile Station Equipment Identity

(IMEI) and to configure dedicated power control and handover parameters

for the weak reception UEs. Based on the parameter settings, weak

reception UEs obtain a high downlink power control threshold in weak

coverage areas and perform handovers at the designated threshold. This

prevents frequent compressed mode measurements and call drops caused

by signal quality fluctuations.

The Voice Experience Improvement for Weak Reception UEs feature

involves two major procedures:

1. Weak reception UE identification: Upon receiving a CS service setup request from a UE, the

RNC identifies the UE type based on the IMEI Type Allocation Code (TAC).

2. Differentiated handling: The RNC assigns the weak reception UE dedicated radio performance

parameters for differentiated power control and handovers.

In areas not covered by a GSM network or areas with poor coverage, only

differentiated power control is recommended for this feature.

Page 6




Identification of Weak Reception UEs

Obtaining the IMEI:If the IMEI acquisition function is enabled on the CN, the CN obtains the IMEI. If the IMEI acquisition function is disabled on the CN, the RNC

obtains the IMEI. IMEI obtained by the CN: When a UE initiates a CS service setup request, the CN sends an Identity Request message to the UE to request

its IMEI. Then, the RNC extracts the IMEI contained in the Identity Response message sent from UE to the CN.

IMEI obtained by the RNC: When a UE initiates a CS service setup request, the RNC rather than the CN sends an Identity Request

message to the UE to request its IMEI after the security mode procedure has been successfully performed. The

RNC_CS_QUERY_UE_IMEI_SWITCH switch under PROCESSSWITCH2 specifies whether to enable the RNC to obtain the IMEI.

Identifying weak reception UEs After obtaining the IMEI of a UE, the RNC extracts the TAC from the IMEI and checks whether the TAC is contained in the TAC list, which is

configured by running the ADD UIMEITAC command.

If the TAC is contained in the TAC list, the RNC determines that the UE is a weak reception UE and performs subsequent differentiated

handling procedures.

If the TAC is not contained in the TAC list, the RNC determines that the UE is not a weak reception UE and does not perform d ifferentiated

handling procedures.

3. The RNC sends an MM NULL

message to the CN to prevent the

message serial number inconsistency

between the UE and the CN.

2. According to the instructions, the UE

sends the RNC an Identity Response

message containing its IMEI.

1. The RNC rather than the CN sends an

Identity Request message to a UE to

request its IMEI.

Page 7




Differentiated Power Control

After identifying a UE as a weak reception UE, the RNC configures dedicated maximum radio link (RL)

downlink (DL) transmit power for the weak reception UE, which ensures that the weak reception UE obtains

higher RL DL transmit power when CS signal quality is unfavorable.

Increasing the maximum RL DL transmit power affects the cell capacity. Therefore, when the RNC receives a CS voice service

setup request from a weak reception UE, the RNC decides whether to configure the maximum RL DL transmit power for the

weak reception UE based on the DL Transmitted Carrier Power (TCP) in the cell.

If the TCP in the cell is smaller than or equal to the value of SpecUserPwrEnDlPwrTrigThd, the RNC configures a high

maximum RL DL transmit power based on the SpecUserRlMaxDlPwr setting. If the TCP in the cell is greater than the value of SpecUserPwrEnDlPwrTrigThd, the RNC configures a normal maximum RL

DL transmit power based on the RLMaxDlPwr setting.

Note: SpecUserRlMaxDlPwr takes effect only on 12.2 kbit/s adaptive multi-rate (AMR) services carried on DCHs. For CS and

PS services at other rates, the maximum RL DL transmit power is still specified by RLMaxDlPwr .

Differentiated power control does not apply to CS voice services carried over HSPA.

SPECUSER_AMR_PWRENHANCE_SWITCH under SpecUserFunctionSwitch controls the differentiated power control

function. When SPECUSER_AMR_PWRENHANCE_SWITCH is selected, the RNC performs differentiated power control on a

weak reception UE.

NodeB

UMTS

Higher DL max power

Normal DL max power

Weak reception UE

Normal reception UE

UMTS

Page 8

http://findicons.com/icon/457543/htc_evo_4g

http://findicons.com/icon/457539/apple_iphone_4




Differentiated Handovers

SpecUserHystFor2D: Delay in reporting the 2D event for special UEs.

SpecUserCSThd2DEcN0: Ec/N0 threshold for special UEs to report the 2D event.SpecUserCSThd2FEcN0: Ec/N0 threshold for special UEs to report the 2F event.

SpecUserCSThd2DRSCP: RSCP threshold for special UEs to report the 2D event.

SpecUserCSThd2FRSCP: RSCP threshold for special UEs to report the 2F event.

SPECUSER_AMR_HOENHANCE_SWITCH under SpecUserFunctionSwitch controls the

differentiated handover function. When SPECUSER_AMR_HOENHANCE_SWITCH is selected,

the RNC performs a differentiated handover on a weak reception UE.

In areas not covered by a GSM network or areas with poor coverage, differentiated

handovers are not performed.

Weak reception UEs in the same radio environment can experience great fluctuations in signal quality.

This results in event 2D or 2F being reported frequently and also results in frequent compressed modemeasurements, which may cause call drops.

To address this issue, the RNC configures dedicated 2D/2F parameters for weak reception UEs to

prevent frequent compressed mode measurement, reduce call drops, and improve voice experience

for weak reception UEs. The parameters are as follows:

Page 9




Feature Dependency

This feature does not depend on and can be used with any

other features.

Page10




Feature Impact

Page 11

Number of

UEs

Processing

AMR Services

at the Cell

Edge

HSDPA

Throughput

(kbit/s)

HSDPA Throughput

After a 3-dB Increase in

the Maximum RL DL

Transmit Power for

UEs Processing AMR

Services (kbit/s)

Cell Capacity Reduction

Percentage After the

Increase (Percentage of

3 dB in the Total Cell

Power)

Throughput

Reduction

Percentage

After the

Increase

1 9062.0 9048.8 0.23% 0.15%

2 8926.2 8867.9 1.83% 0.65%

4 8701.1 8570.3 3.62% 1.50%

8 8107.1 7737.0 12.10% 4.57%

The RNC configures a high RL DL transmit power for weak reception UEs, which increases the

transmit power in the cell. When a cell has fixed DL transmit power, this feature imposes impacts on

cell capacity and HSDPA throughput. This page describes the impacts based on the followingsimulations conducted by Huawei:

• An HSDPA cell exists.

• Two HSDPA UEs of category 10 are processing downlink services at the center of the cell, and

the channel quality indicator (CQI) is about 30.

• UEs processing adaptive multi-rate (AMR) services locate at the cell edge (the Ec/N0 is –16 dB).

The maximum RL DL transmit power remains unchanged or increases by 3 dB.

The simulation results show that this feature has a small impact on cell

capacity and throughput.




Application Scenarios and Gains

Scenario with the GSM coverage much better than the UMTS coverageIn this scenario, call drop rate reduces to about 5% for weak reception UEs

after differentiated power control or differentiated handover is enabled. As a

result, the total call drop rate reduces to about 10%.

Scenario with no GSM network or poor GSM coverage

In this scenario, all drop rate reduces to about 5% for weak reception UEsafter differentiated power control is enabled.




Contents

1 Feature Description

2 Feature Plann ing








Feature Activation Requirements and

Information Collection

Page 14

Feature activation suggestions

Before deploying Voice Experience Improvement for Weak Reception UEs, analyze the

network coverage and the causes of high call drop rate of weak reception UEs. This feature is

recommended when a UMTS network meets all of the following conditions:

The weak reception UE's penetration rate is above 10%.

The call drop rate of weak reception UEs is above average.

The call drops are closely related to poor UMTS network coverage.

In areas not covered by a GSM network or areas with poor coverage, only differentiated

power control is recommended.

Currently, this feature applies only to iPhone 4 and iPhone 3GS.

Information collection before deployment

Before deploying this feature, the TAC information for weak reception UEs must be collected.In addition, check whether the IMEI acquisition function is enabled on the CN. If not, this function

must be enabled on the RNC.




Network Planning

VersionThis feature requires the RAN14.0 or later versions.

License

A license for Voice Experience Improvement for Weak Reception UEs

must have been activated.

Impact on NEs

This feature is implemented on the RNC and has no impact on UEs,

NodeBs, and CNs.




Contents


2 Feature Planning

3 Featur e Deployment







Data Preparation

Page 17

Name Parameter ID Description Data SourceHandover Enhanced

Switch for Special UEs for

Speech QualityImprovement

SpecUserFunction

Switch:SPECUSER

_AMR_HOENHANCE_SWITCH

To enable differentiated handover for the Voice Experience

Improvement for Weak Reception UEs feature, perform the

following steps:

Set TAC_FUNC to Special_User_Enhance.

Select SPECUSER_AMR_HOENHANCE_SWITCH under

SpecUserFunctionSwitch .

Network plan

Power Enhanced Switch

for Special UEs for

Speech Quality

Improvement

SpecUserFunction

Switch:SPECUSER

_AMR_PWRENHA

NCE_SWITCH

To enable differentiated power control for Voice Experience

Improvement for Weak Reception UEs, perform the following

steps:

Set TAC_FUNC to Special_User_Enhance.

Select SPECUSER_AMR_PWRENHANCE_SWITCH under

SpecUserFunctionSwitch .

Network plan

Threshold for the

transmit power of

carriers in a cell.

SpecUserPwrEnDl

PwrTrigThd

This parameter must be configured for differentiated power control

on weak reception UEs.

A large value of this parameter leads to a significant decrease in

the call drop rate of AMR services of the weak reception UE

identified by the TAC, but a high probability of cell capacity

reduction. A small value of this parameter leads to a subtle

decrease in the call drop rate of AMR services of the weak

reception UE identified by the TAC, but a low probability of cellcapacity reduction. The recommended value is 80.

Network plan

Maximum transmit power

of special UEs requiring

good voice experience.

This parameter applies

only to 12.2 kbit/s AMR

services.

SpecUserRlMaxDl

Pwr

A large value of this parameter leads to a decrease in cell capacity.

A small value of this parameter leads to an increase in the call drop

rate of AMR services of the weak reception UE identified by the

TAC. The value 30 is recommended for 12.2 kbit/s AMR services.

Network plan




Name Parameter ID Description Data Source

Delay in reporting the 2D event. SpecUserHystFor2D This parameter setting is related to slow fading. A large value of this parameter

leads to a low probability of ping-pong handovers and incorrect decisions, but a

long delay for triggering event 2D. A small value of this parameter leads to a

high probability of premature compressed mode startups, which reduces the

cell capacity. The recommended value is 6.

Network plan

Ec/N0 threshold for special UEs

to report the 2D event.

SpecUserCSThd2DEcN0 A large value of this parameter leads to premature compressed mode startups,

which increases the compressed mode startup period, reduces cell capacity,

and negatively affects downlink cell coverage. A small value of this parameterleads to delayed compressed mode startups and untimely handovers, which

increases the call drop rate. The recommended value is –13.

Network plan

Ec/N0 threshold for special UEs

to report the 2F event.

SpecUserCSThd2FEcN0 This parameter is used together with SpecUserCSThd2DEcN0. A large value

of this parameter leads to a long compressed mode startup period, which

reduces the cell capacity and negatively affects downlink cell coverage. A

small value of this parameter leads to a high probability of ping-pong

handovers. The recommended value is –10.

Network plan

RSCP threshold for special UEs

to report the 2D event.

SpecUserCSThd2DRSCP A large value of this parameter leads to premature compressed mode startups,

which increases the compressed mode startup period, reduces cell capacity,

and negatively affects downlink cell coverage. A small value of this parameter

leads to delayed compressed mode startups and untimely handovers, which

increases the call drop rate. The recommended value is –93.

Network plan

RSCP threshold for special UEs

to report the 2F event.

SpecUserCSThd2FRSCP This parameter is used together with SpecUserCSThd2DRSCP. A large value

of this parameter leads to a long compressed mode startup period, which

reduces the cell capacity and negatively affects downlink cell coverage. Asmall value of this parameter leads to a high probability of ping-pong

handovers. The recommended value is –90.

Network plan

If the switch

Special_User_Enhance is

selected, the TAC specifies the

UEs that are enabled with the

Special User Enhance feature.

TAC_FUNC To enable Voice Experience Improvement for Weak Reception UEs, set

TAC_FUNC to Special_User_Enhance.

Network plan

Data Preparation




Feature Activation

Page 19

The following procedure is used to activate Voice Experience Improvement for Weak Reception UEs:Step 1: (Optional) Run the following MML command to turn on the switches for obtaining the IMEI and for sending the MM NULL

message on the RNC:

SET URRCTRLSWITCH: PROCESSSWITCH2=RNC_CS_QUERY_UE_IMEI_SWITCH-1,PROCESSSWITCH4=SEND_MSG_NULL_SWITCH-1; Note: If the CN does not check the message serial number, the switch for

sending the MM NULL message does not need to be turned on.

If the CS IMEI acquisition function is enabled on the CN, this step is not required.

Step 2: Run the following commands on the RNC to enable the iPhone Voice Experience Improvement feature, add the iPhone IMEI

TAC, and enable the differentiated handling:

(The following parameter values are used for reference and must be determined based on live network conditions.) In the scenario with the GSM coverage much better than the UMTS coverage, enable both the differentiated power control and

differentiated handovers:

ADD UIMEITAC: TAC_FUNC=Special_User_Enhance, TAC=XXXX, Description="iPhone",

SpecUserFunctionSwitch=SPECUSER_AMR_HOENHANCE_SWITCH-1&SPECUSER_AMR_PWRENHANCE_SWITCH-1; ADD UCELLLDM:

CellId=XX, SpecUserPwrEnDlPwrTrigThd =80;

MOD UCELLRLPWR:

CellId=XX, CNDomainId=CS_DOMAIN, MaxBitRate=12200, RlMaxDlPwr=0, SpecUserRlMaxDlPwr =30;

SET UHOCOMM:

SpecUserHystFor2D=6, SpecUserCSThd2DEcN0=-13, SpecUserCSThd2FEcN0=-10, SpecUserCSThd2DRSCP=-93,

SpecUserCSThd2FRSCP=-90;

In the scenario with no GSM network or poor GSM coverage, enable only the differentiated power control:

ADD UIMEITAC: TAC_FUNC=Special_User_Enhance, TAC=XXXX, Description="iPhone",

SpecUserFunctionSwitch=SPECUSER_AMR_HOENHANCE_SWITCH-0&SPECUSER_AMR_PWRENHANCE_SWITCH-1;

ADD UCELLLDM:

CellId=XX, SpecUserPwrEnDlPwrTrigThd =85;

MOD UCELLRLPWR:CellId=XX, CNDomainId=CS_DOMAIN, MaxBitRate=12200, RlMaxDlPwr=0, SpecUserRlMaxDlPwr =30;




Contents


2 Feature Planning


4 Perform ance Optimization






Performance Monitoring (1)

The following procedure is used to monitor this feature effect:

1. Prepare a weak reception UE whose TAC is contained in the IMEI TAC list on the RNC. Obtain the international mobile subscriber identity

(IMSI) of the weak reception UE, and then start UE tracing on the RNC side.2. Use the weak reception UE to initiate a CS call in a cell configured with related differentiated power control parameters.

3. View the UE signaling messages to check whether the values of the following information elements (IEs) contained in the signaling

messages are the same as the parameter settings:

Parameter confirmation of the maximum RL DL

transmit power

2D/2F event parameter confirmation




Performance Monitoring (2)

Page 22

The following counters are added on the RNC to calculate the number of CS radio access bearers (RABs) abnormallyor normally released for special UEs in cells.

Counter Description Meaning

VS.RAB.SpecialUser.

AbnormRel.CS

Number of CS RABs

Abnormally Released for

Special UEs for Cell

This counter measures the number of CS

RABs abnormally released for special UEs in

the best cells.

VS.RAB.SpecialUser.

NormRel.CS

Number of CS RABs

Normally Released forSpecial UEs for Cell

This counter measures the number of CS

RABs normally released for special UEs in thebest cells.

Based on the preceding counters, the following key performance indicator (KPI) is added on the

RNC. This KPI is calculated with the following formula:Call drop rate of special UEs = VS.RAB.SpecialUser.AbnormRel.CS/

(VS.RAB.SpecialUser.AbnormRel.CS + VS.RAB.SpecialUser.NormRel.CS) x 100%

Gain evaluation

To evaluate the gain of this feature for weak reception UEs, do as follows:

1. Obtain data about the call drop rate before and after enabling this feature and about call drop

causes.

2. Compare the gain based on the data about call drops caused by weak coverage.

Performance monitoring




Contents


2 Feature Planning



5 O&M and Troubleshoo t ing





O&M and Troubleshooting

Troubleshooting

When the feature is faulty, disable the feature and the system is not

affected.

IMEI TAC list update

The RNC identifies weak reception UEs based on the IMEI TAC. To

estimate gains correctly, ensure that the RNC is configured with the

latest IMEI TAC list.






Reference Document

FPD: Voice Experience Improvement for Weak Reception UEs




Acronyms & Abbreviations

TAC: type allocation codeIMEI: international mobile station equipment identity

CQI: channel quality indicator



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Documents

Introduction to the RAN14.0 Feature–Voice Experience Improvement for Weak Reception UEs V0.4