GBO 010 E1 1 Network Optimization Overview-63

GBO_010_E1_1 Network optimization overview

ZTE UniversityGSM-BSS D&T Team

Objectives

At the end of this course, you will be able to: State network optimization flow and the Content Master common network optimization problems

analysis and solution Understand Dual-Band Network and its peculiar

problems and solutions

Contents

Overview of radio network optimization

Introduction of network performance evaluation

Flow of Radio Network Optimization

Routine network optimization tasks

Common network optimization problems

Dual-Band network optimization

Object Purpose

The upcoming network Network in operation

Improve system performance Maximize service quality under existing system

configuration Maximize benefit of existing network Suggestion of network future maintenance and

planning

NetworkOptimization

Data Collection

Data Analysis

Confirm Reason

Make Solution

Solution Implement

Network Optimization Concept

Overview of network optimization

Cause of Network Optimization

End-user changes

New calling model

Subscriber distribution change

Environment change

New Building,Road,Vegetation

Network structure changes

Coverage , Capacity

Application of New

Technology

New Equipment

New Standard

Why Optimization


Network Optimization Position

Position in mobile communication

Specific working flow of mobile networks

Throughout network planning, implementa

tion and daily maintenance

Closed-loop management of network quali

ty

Necessary and effective approach of Impr

oving network operation quality

Relation with Maintenance

Maintenance is the foundation of net

work optimization

Network optimization is the further de

velopment based on maintenance

Maintenance focus on equipment,

Network optimization focus on networ

k,

Maintenance work is the network valu

e-keeping process

Optimization is the network value-add

ed process


Network optimization category

Commission and maintenance optimization

ZTE equipments were not us

ed in network optimization, but

network operator wants us (as t

he third party) to do network qu

ality evaluation, optimization adj

ustment, complementary planni

ng, etc.

Independence Optimization

Network optimization

category

Engineering network optim

ization

Maintenance network opti

mization


Content







Network Evaluation

Object

Network in operation

MeansCheck and analyze:•Collection customers’ complain,•frequency allocation•radio parameter, •BTS equipment•MSC data •System performance data

ObjectivesOutput reasonable and objective evaluation•network planning quality, • network running condition,• network operation question, the hidden danger,• network investment utilization factor

Concept


Drop call rate

TCH/SDCCH congestion rate

TCH allocation success rate

Handover success rate

Radio coverage

Traffic

Channel available rate

Optimization

Voice quality

KPI

Network performance KPI


Performance evaluation

Analyze network KPI and output optimization suggestion

Resource utilization evaluation

By traffic statistic, export Traffic, calculate the utilization of network resources.

Reflect the capacity of network

Network layoutevaluation

Network size, types of coverage, the feature / topographic distribution, networ

k architecture, site / Traffic density, indoor coverage strategy

Network test evaluation

Through DT and CQT test, simulate users calling process. Reflect the user’s f

eeling of communication

Voice quality evaluation

Evaluate voice quality by MOS

Network evaluation content


Contents







1 2 3 4 5

Detailed Flow

Dataanalysis

Require analysis

Data collection

Preparation Equipment check

86

Adjust plan

Summary acceptance

7

Result verify

Requirement analysis

Flow of network optimization

Network status: coverage, voice quality ， radio KPI,

topographic and geographic feature, population dis

tribution, traffic hot spot

The most important problem of existing network

Expected performance KPI and dead line

Working interface with operator

Analysis Framework21 3 4 5

Data analysis

preparation Data collection

Requireanalysis

Equipment check

86Adjust plan

Summary

acceptance

7 Result verifies

GoalsDetail

requirement

Expectations indicatorsEstimate time Special requests

Further detail operator requirement

Prepare data & equipment

History P&O reportDigital map Site information Network Index DT and related test equipment …………

Preparation



Data analysis

Equipment check

Data collection

Require analysis

preparation86

Adjust plan

Summary

acceptance

7 Result verifies

Avoid the Hardware

problems to affect overall network

performance

Checking object

BTS hardware faultAntenna and feeding cableClock problemUnstable power supply systemWorking environment conditionBSC/OMCR fault

Equipment check



Data analysis

Equipment check

Data collection

Require analysis

Preparation86

Adjust plan

Summary

acceptance

7 Result verify

Current service condition

System performance data Field test data

Subscriber complaints

Signaling trace

The data directly related to call processing of mobile system in MSC

Data collection



Data analysis

Equipment check

Datacollection

Require analysis

Preparation

86 Adjust plan

Summary

acceptance

7 Result verify

Traffic statistics Drive test

Longer period data

Comprehensive analysis of relative KPI

Reflect downlink signal situation

Signaling data

Analysis coordination between system entity

Provide essential clue for network failure

Subscriber complaints The non-professio

nal data Need confirmation

again

Data analysis



Data analysis

Equipment check

Data collection

Require analysis preparation

86Adjust plan

Summary acceptance

7Result verify

Make plan

Risk control Avoid frequent

adjustmentPartial experiment plan Quickly rollback plan Implementation step BackupReasonable time Agreement from

operator

Check plan

Audit by the expert and operator

Confirm feasible solution

Implementation

Detailed record optimization process and results

Adjust optimization plan



Data analysis

Equipment check

Data collection


86 Adjust plan

Summary acceptance

7 Result verify

PerformanceComparison

Comparison oftest

Compare DT result. Compare CQT result.At the same test period and route

Compare and analyze the data before and after adjustment

Verify result



Data analysis

Equipment check

Data collection


86Adjustplan

Summary acceptance

7 Result verify

Optimization report

Project acceptance

Accept on standard

Operator involved

Signed by operator

Project summary

Knowledge transfer

Job evaluationDocument backup

The work doneThe achievement obtained

Summary and acceptance


Contents




Routine network optimization



Netw

ork m

onito

r BSS parameter a

djustment

RF Optimization

Three kind of routine work


Performance statistics

CCCH

Radio resource assignment Channel mode Dedicated channel assignme

nt Handover Channel release Channel establish

Several important counters

Abis interface

A interface

BSC

cell

Neighbor cell list

Several key network element

Some specific event can trigger corresponding counter to do add 1 for counting, through the observation of counters in a specific period of time, We can know the network running status

Network monitor


Statistics report tableConcept

Network performance statistics report come from the calculation of c

ounters.

Quality KPI Statistical report reflect faults and solution

Drop call

Handover

Can’t call (block, interference...)

Network access (large coverage,

indoor coverage...)

Voice quality

Hard fault ： Failed board or partial failure of eq

uipment. Generally hard faults can generate obvious

warning information on OMC-R

Soft fault ： System still running, but part of system is unstable or not in the best status

Network monitor


Other monitor methods

DT and

CQT

Subscribe

r feeling and

customer

complaints

Environment

New buildingExternal interf

erence

Network monitor


Network identification parameters System control parameters

Cell selection and re-selection parameters Network function parameters

Radio parameter

Identify MS and network The parameters related to system

configuration. Which will Influence

the service load and signaling flow

of the system (capacity)

The parameters related to cell selection and cell re-selection, which will affect coverage

The parameters that provide various system functions

BSS parameter adjustment



Selection and reselection parameters

System control parameters

Network function parameters

Network

identification

parameters Radio

parameter

CGI ：

BSIC ： BSIC ＝ NCC&BCC



Selection and

reselection

parameters

System

control

parameters

Network function parameters

Network identification

parametersRadio

parameter

IMSI attach detach

Common control channel configuration (CCCH CONF)

Access allowed reserved blocks (BS AG BLKS RES)

Paging channel multiplexing frames (BS PA MFRMS)

Periodic location update timer (T3212 ） Radio Link Timeout

Permitted network color code （ NCC PERMITTED ） Maximum retransmission times (MAX RETRANS)

Transmission distributed timeslots （ TX INTEGER ） Cell access barring （ CBA ） Wait time （ T3122 ） Multi-band indication （ MULTIBNAD ）



Selection and reselection

parameters

System control

parameters

Network function

parameters


parameters Radio

parameter

Additional re-selection

parameter indication (ACS)

Reselection parameter indication (PI)

Cell barring qualifying （ CBQ ） Cell reselection offset （ CRO ） Temporary offset （ TO ） Penalty time （ PT ） Cell reselection hysteresis (CRH)

Maximum power level of the control chann

el （ MS TXPWR MAX CCH ） Allowed access minimum receiving （ RX

LEV ACCESS MIN ）


Selection and

reselection

parameters

System control

parameters

Network function

parameters


parameters Radio

parameter

Power control indication (PWRC ） discontinuous transmission （ DTX ） New establishment cause indication (N

ECI ） Call reestablishment allowance （ R

E ）



Some BSC timers

T3111 ： Timer between ch

annel release and RF deactivat

ion.

T3101 ： Waitting timer used in immediate assignment process.

T3103 ： Intra-BSC handover timer to hold TCH both in original and target cells

T3109 ： used limit SACCH release time in case of a radio link timeout.

T3107 ： used to restrict the TCH assignment time



Check balance of UP/DOWN link

Feeder cable check

Check interference of UP/DOWN link

Antenna check

Azimuth

Tiltdown angle

Height

Isolation

Cross connection

VSWR high

Connector loose

Signal leakage RF

Optimization

RF Optimization


Check balance of UP/DOWN link

Feeder cable check

Check interference

of UP/DOWN link

Antenna checkRF

Optimization

Uplink Interference

Check the ratio of un-decoded

RACH and uplink signal quality

handover to determine internal or

external uplink interference.

Repeated change frequency

Check idle channel interference

band

Frequency scanner

Downlink

Interference

Cell coverage test

Adjacent channel scan

Co-channel interference

detection

RF Optimization


Check balance

of UP/DOWN link

Feeder check

Check interference

of UP/DOWN link

Antenna checkRF

Optimization

Preparation information ：Link budget used in radio desig

n

BTS functions : DPC,DTX

Cell main parameter

BTS debugging report

Field data coll

ection

Abis signaling trace by OM

CR

Signaling analysis by MA10,

retain measurement report

message

RF Optimization


Contents







Call drop

handover

coverage

interference

congestion

Common Network Optimization Problem


1Common phenomenon

Overshooting

Blind spot Sector cell

Overlaps

Coverage


2

Investigation

Power Control Measure

Rx_LEV Measure

Drop Call Measure

Neighbor Cell

Measure

Undefined neighbor

cell (lonely island)

Locate reason

Cell performan

ce measure

Cell handover

out measure

Coverage


3Problem solution

Add new site

Adjust antenna

and feeder

Coverage solution

Increase power of TRX,MHA

Adjust network parameter

Coverage


1

Common phenomenon

High call drop rate

Bad voice qualityPing-pong

handover

Handover failure

Interference


2

Investigation

Entrance

Regularity of interference band Rx-Lev Performance measurement

Quality handover proportio

nRx-Qual Performance

Measurement

Call drop performance

measurement

Handover failure but reestablishAlso fail

DT, inspect interference area and signal quality distribution

Locate reason

Spectrum scan

frequency-hopping, DTX,DPC

Check equipment problems

Interference


3

Solution

Increase the

distance of co-

channel or

adjacent channel

cell

ReduceBTS

power

Avoid external

interference frequency

Adjust antenna height azimuth

down tilt

Adjust frequency

plan Solution

Narrow beam width antenna

Use frequency hopping,

DTX,DPC

Interference


1

Common phenomenon

Difficult to originate a

call

Incoming

handover failure

Low calling

success rate

Congestion


Congestion

2Investigation － SDC

CH congestion

Unreasonable access parameter

Unreasonable LAC

Small T3212

SDCCH frequency interferen

ce

SDCCH number

Wrong LAC

setting

Too many SM

2Investigation －TCH congestion

•Check equipment hardware•Check TCH Congestion rate


Locatereason

Congestion

3Solution －

TCH congestion

Adjust antenna height, direction, dow

n tilt

Change BTS

power

Open half rate function

Open traffic-based

handover,

directional retry function

solution

Expand TRX or

add new site

Adjust cell access,

reselection and

handover parameter


3Solution －SDCCH congestion

Check cell CRH of

LAC boundary

Rational division of

LAC

Increase SDCCH

Check LAC

setting solution

Adjust cell access

parameter

increase T3212

Check frequency

interference

Congestion


1

Common phenomenon

HO failure

or HO slow Unreasonable

Proportion of out/in HO

Frequent

handover

Handover


Neighbor cell setting check

Define neighbor cell for lonely island

2Investigation and solution

Very high HO failure rate

Neighbor cell high load

Neighbor cell TRX fault

Neighbor cell transmission fault

Same frequency and same BSIC for nearby cells

Lonely island

Interference No enough overlap area between source cell and target cell

Work out hardware problem

Work out neighbor cell problem

Improve radio environment

Improve coverage

1 2 3 4 5

coverageHardwareBad radio

environment Neighbor cell Congestion and transmission fault

Handover


2Investigation and solut

ion

Two transmitting antennas of same cell cover scope is different.

HO aarameters unreasonable or mismatch

Repeater only enlarged part of frequency of a cell.

Check MSC REMOTELAC table

A interface signaling load congestion, lead HO signaling lost

Check antenna condition,

Check and adjust HO parameters

Adjust or replace Repeater

Complete LAC info in MSC

Expansion

6 7 8 9 10Signaling link

Heavy loadAntenna problem LAC Not defined

in MSCRepeater problem

Parameter setting problem

Handover


1

Three type

MS can not decode

SACCH result in RLT tim

eout and dropped calls.

Radio link timeout

HO timer timeout ，MS is unable to acces

s the target channel,

and can not return to t

he original channel as

well.

Handover call drop

Equipment failure

cause the call droppe

d, Such as LAPD link

break and so on

LAPD call drop

Call drop


3Investigation and solution

Blind spot Poor indoor

coverageovershooting

co-channel interference

Adjacent channel interference

Unreasonable parameters.

Neighbor cell not complete

Same BCCH/ BSIC Traffic CongestionClock

asynchronous

Feeder mistake connection

Azimuth and downtilt inconsistent

Antenna, feeder damage, leak water

The transmission break, Interrupt, high BER

Adjust radio para.Adjust engineer p

ara.Solve hardware p

roblem

Adjust engineering para. or frequency plan

Open DTX 、 FH 、 DPC

Solve equipment problems

Adjust para.Balanced traffic Calibration Clock

Analysis traffic statistics

Examination alarm

On-stie check

Observation transmission and board alarm

Transmission path checks

1 2 3 4 5TransmissionCoverage Antenna and

feederHandover Interference

Call drop


3Investigation and solut

ion

such as inconsistent software version

RLT ,Min-Acc-Min, Minimum level of RACH, RACH busy threshold.

Upgrade software check and adjust radio parameters

6 7Unreasonable

radio para. Other reasons

Call drop


Contents







GSM900 macroGSM1800 macro

900 micro1800 micro

P-cell P-cell

GSM900/1800 umbrella-like cell macro

A lot of cells are available for choice.

Concept

Dual band network optimization

Ideal dual-band network

MS roaming in two band network MS can seamless handover between two band network Traffic balance in the dual-band network Avoid frequent re-election and normal location update Avoid frequent unnecessary handover between dual-band network

Dual-band network unique problem

Traffic is not balance

Ideal dual-band network


Frequent location

update

Frequent HO and

reselection

Traffic management principle

Selection principle Traffic balance principle

Layer principle

Automatic traffic balance

technology based on

dynamic priority to

prevent traffic congestion.

900 networks and 1,800 networks in different layer

MS idle: Select the 1800 cell first

MS busy: Remain in the layer

where the call is originated,

and avoid unnecessary

handover between layers.

1800 layer

900 layer

The basic principle


Balance the traffic in du

al-band network

Traffic Balance

While covered by dual-b

and cells ,try to reduce the fr

equent handover and locatio

n update, reduce network sig

naling flow

The efficient use of resources

Traffic control principle


Objective

Adjust cell engineering parameters Adjust cell radio parameters

BTS transmit power Antenna height, azimuth and do

wntilt Antenna type

Through modifying the signal level of dual band cells in the same position, change priority and direction of cell selection, reselection and handover. Balance traffic of dual band cells.

Cell selection ： C1 ， CBA ， CBQCell re-selection ： C2Dual-band handover ：

• PBGT handover control• Handover priority

The main optimization method


900M cell ： CBQ = 1 ， CBA = 0 ， C1=15

1800M cell ： CBQ = 0 ， CBA = 0 ， C1=10

Power on the MS to make cell Power on the MS to make cell selectionselection

Application of Cell Selection


MS select 1800 network first, set the 1800 cell to a normal priority cell CBQ = 0 ， CBA = 0

Set the 900 cell to a low priority cell CBQ = 1 ， CBA = 0

900M cell ： C1=15 ， C2=5

1800M cell ： C1=10 ， C2=20

Cell re-selection in the idle mode

Application of Cell Selection

MS Reselects the 1800 network, set a large offset for the

1800 cell and a small offset for the 900 cell.


1800 cell1800 cell

900 cell900 cell

PBGT PBGT handoverhandover

Bar Inter-layer PBGT Handover

Multi-path fading can

cause a large number

of PBGT handover

80% handover is

PBGT, it must be

barred.


Different layer use different handover priority

Other policiesAutomatic traffic balance poli

cy based on dynamic priority

Traffic-based handover

Directed retry between differen

t bands

Fast fading handoff algorithm

Set handover protection time

Other optimization policies


GBO 010 E1 1 Network Optimization Overview-63

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