2 DriveTest Analysis Ver1-Libre

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Drive Test Analysis

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��Version1.0

� Upon completion of this course, you will be

able to:

�Understand the common procedure

��

�Understand the common procedure

Of drive test data analysis

� Identify the basic problems and cause

of the problems

�Propose the solutions to solve the

network problems

Chapter 1 Chapter 1 Common procedure of drive test data Common procedure of drive test data

analysisanalysis

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Chapter 2 Chapter 2 Case study for drive test analysisCase study for drive test analysis

Chapter 3 Practice on drive test analysisChapter 3 Practice on drive test analysis

Common procedure of DT data analyze

1. Check if the Drive test KPIs meet the requirement. If not, identify the problematic log

files. Capture the figure and events (e.g. locations, time, identify problematic cells)

2. Check the RxLevel and RxQual distribution, check if they are related to the points

that miss the KPI requirement?

3. (If new site or cluster) Check the distribution of each BCCH (CGI), pay attention to

the crossed feeder.

�� !

4. Analyze the points that miss the KPIs point by point. (To make the analysis more

comprehensive , get more information from engineering parameters, BSC data

configuration, traffic statistic and BTS alarms)

5. Identify the possible causes of each problem points ,discuss with customers

4. Propose solutions and get approval from customers before execute the change

request

4. Re- Drive Test to verify the problem after implemented the solutions

Chapter 1 Chapter 1 Common procedure of drive test data Common procedure of drive test data

analysisanalysis

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Chapter 2 Chapter 2 Case study for drive test analysisCase study for drive test analysis

Chapter 3 Practice on drive test analysisChapter 3 Practice on drive test analysis

Coverage

• Downlink RxLevel

• Coverage of single cell

• Coverage of whole network

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Coverage

EIRP(dBm)

L(dB)

Network Coverage is evaluated by:

RxLev = EIRP(dBm) – L(dB)

Where:

EIRP = Effective Isotropic Radiated Power

L = Propagation Losses

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RxLev(dBm)

Unexpected coverage

(overshooting)Good coverage

In urban area, Lower Antenna Height (<=25m), Greater downtilt (>=6 degree),

and Lower EIRP (<=41 dBm) are used to control overshooting & interference.

Coverage(one cell)

� The following example shows the

downlink RxLevel(Dedicated Mode)

decreases when MS is driving away

from BTS.

� The RxLevel decrease faster when

Downtilt: 0 drgree

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Antenna Downtilt increase.

Downtilt: 8 drgree

Variation

due to

shadowing

Global

means

RxL

evel

Variation

s due to

Rayleigh

fading

Coverage(Network)

� The picture shows the coverage of a city, which contains good and bad

coverage areas.

� The distribution of downlink RxLev concentrates from -80 to -95 dBm.

Good Coverage

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Bad Coverage

Coverage Issues

• Coverage hole

• Sudden Decrease on Signal Level

• Line of Sight Lost

• Lack of Dominant Server

• Coverage Overlapping

• Overshooting

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• Overshooting

Coverage Hole

RxQuality

RxLevel

Legend

Poor Coverage

AreasBad RxQuality

Call Drop

��

� RxLevel(Serving Cell) is about (or less than) -95 dBm

� RxLevel(Neighbours) are about (or less than) -95 dBm

Sudden Decrease on Signal Level

� RxLev(Serving Cell and

Neighbors) decrease in a

short time.

� Check if there is big change

of testing environment, e.g.

check if the test was

performed on a highway

��

and that particular area was

a tunnel or not.

� Signal level on the chart will

make a curve rather than

unstable changes.

� This usually cause Ping

Pong Handovers

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Line of Sight Lost

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Signal Strength of Serving cell make fast up and down due to far away server being blocked by obstacles from the terrain. The other way, signal from the server lose line of sight(LOS) to the mobile because of a hill of something.

RxQuality goes worse when the level drops down fast

Lack of Dominant Server

� Signal Level of more

than one cell (Serving

Cell and Neighbors) are

not high enough.

� This might happen

because the MS is

located on the cell

�� &!

located on the cell

borders and there is no

any best server to keep

the call.

� Lack of Dominant Server

Causes too many

handovers

Coverage Overlapping � Signal Level of 3–4

cells are too closed to

each other.

� This might point

overlapping cells.

� This will cause quality

��

problems because of

frequency reuse and

frequent HO

� Immediate action to

optimize cell coverage

should be taken by

power reductions,

downtilt or other

configuration changes.

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Overshooting

BTS

Serving

cellOther cell B

BSIC 1

Freq. A

� MS is covered by the

serving cell, but is

outside the cell

� BSC thinks that it is

neighbor cell A and

makes a handover to

cell A

� The MS is not near cell

A so the assigned TCH

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Coverage spot

(island effect)Neighbour cell A

BSIC 1

Freq. A

A so the assigned TCH

for the handover is not

used

� Cell A will have unused

TCH (handover)

� The call might be

dropped because it

cannot make the

handover or bad quality

Propose solutions for Coverage Issue

� Solution of low coverage

� Solution of no dominant cell ,overshooting and overlapping

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Solutions of Low Coverage

Possible solution can be listed as below:

� New Site Proposal

� Sector Addition

� Site Configuration Change (Antenna Type, height, azimuth, tilt changes)

� Loss or Attenuation Check ( Feeders, Connectors, Jumpers, etc..)

Proposal Remark How to do

New Site ProposalMost effective solution,

but the cost is highest

Using prediction tool(U-net) to identify the best

locations to put new sites

�� &$

but the cost is highest locations to put new sites

Sector AdditionEffective solution

but only for Omni-Site

Using prediction tool(U-net) to identify the

recommended azimuth of new sectors

Antenna

Height Difficult, high cost


recommended height, type, azimuth or down tilt of

sector.

Type Difficult, high cost

Azimuth Easy to operate

Downtilt Easy to operate

Hardware

Feeders Only for troubleshooting

Referring to hardware checking guide

Connectors Only for troubleshooting

Jumpers Only for troubleshooting

Solutions of overshooting or overlapping

Possible solution can be listed as below:� Site Configuration Change (Antenna Type, height, azimuth, tilt changes)

� Cell Configuration Change (Carrier Power Type, Static TRX Power Class, Fine Tuning

of Static TRX Power…)

Proposal Remark How to do

Antenna

Height Difficult, high cost


recommmended height, type, azimuth or

Type Difficult, high cost

Azimuth Easy to operate

�� &%

recommmended height, type, azimuth or

downtilt of sector.

Easy to operate

Downtilt Easy to operate

Parameter Output Power relatedEasy to operate, but with

risk of coverage reduction

Referring to Data Configuration Reference

Help

What is crossed feeder issue (1)

The term crossed feeder is used to describe the problem that

arises when the feeders for two or more sectors in a site are

inadvertently connected incorrectly. For Example, consider a new

cell site that has three sectors, A, B, and C:

Cross Feeder

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� The crossed feeder problem would arise

if the feeder for sector A is connected to

sector C and vice versa. When this

happens, the sectors typically continue

to provide good coverage. However, the

network parameters for the two sectors

are also reversed. For example, the

parameters storing the sectors' BCCH

and lists of adjacent sectors would be

�� &

and lists of adjacent sectors would be

swapped.

� For example, suppose we run a drive test

through the area served by the cell

whose feeders are crossed display the

ServBCCH attribute on the Map while

the cell sectors are colored by BCCH.

This is what we might see:


� There are 3 types of crossed feeder:

� Crossed transmit feeders

� Crossed receive feeders

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� Crossed transmit and receive feeders

The problems raised by crossed feeder issue

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Crossed Feeder SituationNormal Situation

The problems raised by crossed feeder issue

� Crossed feeder will raise many problems, such as:

� A greater degree of interference

� A poor uplink signal strength

�� !

� A poor performance of handover

How to detect crossed feeder issue by DT


Crossed transmit feeders will result in the swap of 2 or more sectors

BCCH frequency and TCH’s. As the sectors are pointing in the

incorrect direction, performance will suffer as the frequency plan has

been changed and a greater degree of interference will be present.

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In DT, we will find that the handset receives the signal which shouldn't

have been received in the current cell.



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In the example shown above, point A is in the area of coverage of Cell

D3, but the handset at point A receives the stronger signal of Cell D2. It

indicates that TX feeders were crossed between Cell D3 and Cell D2.



It is not easy to detect this fault by DT, because the BCCH frequencies will

appear exactly as they were designed. However, the statistics for the cell

would help us to detect the fault:

�� #

would help us to detect the fault:

� Uplink signal strength would be very poor

� Link balance would be larger than expected

� Handover success rate would be very low



The MR measurement is very useful in detecting this type of feeder

cross.

Uplink-and-Downlink Balance Measurement per TRX and TCH

Receive Level Measurement per TRX are the most useful statistics .

�� $

For example, if the uplink-and-downlink balance is always in level 10

or level 11, we can consider that there is something wrong in the

receive path of the site, crossed receive feeder is a possible problem.


� Crossed transmit and receive feeder

The symptom is similar with the fault “crossed transmit feeder”, and we can

detect the fault by DT easily .

�� %

� Downlink RxQual Issue

�What is RxQual Issue

�The problems raised by RxQual issue

� How to detect quality issue by DT

�Bad Quality due to Signal Strength FER is Bad

Poor Quality Issue

��

�Bad Quality due to Signal Strength – FER is Bad

�Bad Quality due to Signal Strength – FER is OK

�Bad Quality due to C/A Interference

�Bad Quality due to Time Dispersion

� The solution to RxQual issue

What is RxQuality Issue

� Bad RxQual is one of the biggest problems in a Network. The RxQual

that a network operator can offer to customers mostly depends on the

RxLevel and the interference of the network.

� There are two types of RxQual problems, uplink RxQual and downlink

RxQuality. We can only detect downlink RxQual problem by DT,

however, if the downlink RxQual is bad in one cell, there is a risk that

�� &

however, if the downlink RxQual is bad in one cell, there is a risk that

there would be problems on the uplink as well.

What is RxQual Issue

��

Bad

RxQua

lity

Good

RxQua

lity

RxQual is divided into eight levels which are from 0 to 7, the level 0 is the

best and the level 7 is the worst.

The problems raised by RxQual Issue

� Bad RxQual may raise many problems, such as:

� Difficulty in accessing the network

� Dropped calls due to bad quality

��

� Dropped calls due to bad quality

� Poor handover success rate

� Low MOS value (poor speech quality)

Bad Quality due to Signal Strength – FER is Bad

� As the signal strength drops

down, the quality of the call

becomes worse being effected

by interference and/ or fading.

Consequently the system

becomes weaker to handle the

interference.

� Drop calls and ping pong

handovers usually happen in

�� !

handovers usually happen in

such environments.

�RxLev (Serving Cell and

Neighbors) is not high enough

(about less than -95dbm).

� Maybe there are

interferences in this region for

bad FER.

Bad RxLev

Bad RxQual

Bad FER

Bad Quality due to Signal Strength – FER is OK

�This case is similar with

the previous except for

FER. Signal strength is

also bad in this, but FER is

still fine.

� FER is ok, it means that

there is no obvious

interference in the area.

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interference in the area.

The coverage is usually

the problem in this

situation.

Bad RxLev

Bad RxQual

Fine FER

Bad Quality due to C/A Interference

�There is adjacent channel

interference in this case and

the RxQual is not good.

�Bad Quality due to Adjacent

Interference.

�Adjacent BCCH between

best server and best neighbor.

�� '

Bad Quality due to Time Dispersion

Site

�� #

Time dispersion is caused by the reflections. The MS uses all or most of the

received power, instead of only the direct signal, there is a larger probability to

decode the information. So the RxQual will be very bad perhaps.

MS

Reflecting object

Bad Quality due to Time Dispersion

�The MS is near the

cell, it is less than 1

mile far away.

�The RxQual is very

bad for the bad C/R,

in which, R stands for

reflected signal and C

stands for original

�� $

stands for original

signal.

� The TA is too high.

It is because that TA

stands for the

reflected signal but

the original signal.

The solution to RxQual issue (1)

RxQual Issue Solution

Bad Quality due to Signal Strength – FER is

Bad

Find out the interference source

(e.g. frequency planning) or /and

adjust the azimuth or down tilt of

the antenna or /and adjust the

�� %

Bad the antenna or /and adjust the

power of the transmitter(s) to

improve coverage

Bad Quality due to Signal Strength – FER is

OK

There is no obvious interference in

this situation. Adjust the azimuth or

down tilt of the antenna or /and

adjust the power of the

transmitter(s) to improve coverage

The solution to RxQual issue (2)

RxQual Issue Solution

Bad Quality due to C/A

Interference

Avoided adjacent frequencies in the same cell

and preferably in neighboring cells as well.

�� !(

Bad Quality due to Time

Dispersion

Move the site to be placed near the reflecting

object to prevent time dispersion. Another

efficient solution is to modify the antenna

arrangement, either in azimuth (horizontally) or

by tilt (vertically).

Interference Issue

� Hardware Problem

� TRX Problem

� Feeder & Arrester Problem

� Intra-Interference

��

� Adjacent channel & Co-channel

� Inter-modulation Interference

� Inter-Interference

� Other Equipment

Co-Channel & Adjacent Channel Interference

As beside Figure show Station A~D,

Supposing the frequency N have

already allocated to cell A-3.so

frequency N can not be allocate to

��

frequency N can not be allocate to

A1、A2、B1、B2、B3、C1、C2、

C3、D1、D2、D3; and frequency

N±1 can not be allocated to cell A1、

A2、A3、B1、C2、D1、D2

(No ,hoping)

Co-Channel & Adjacent Channel Interference

As below, From the neighbor

list ,BCCH 73 interfered

BCCH 72,it is adjacent

interference. When the co

channel or adjacent channel

happen

��

It will bring the strong

interference. The typical

phenomena:

�High Rxlev

�Worst Rxqual

C/I Problem

� C/I Definition

C/I: Carrier signal /Interference signal

� Optimize C/I method

� Improve Coverage

��

� Improve Coverage

�Decrease Interference

C/I Problem due to poor coverage

��

� RxLevel(Serving Cell) is about (or less than) -95 dBm;

� RxLevel(Neighbours Cell) is about (or less than) -95 dBm;

Result: Worst C/I due to poor coverage.

C/I Problem due to Interference (frequency)

�� !'

� RxLevel (Serving Cell) is about -70dBm; (strong)

� RxLevel (Neighbors Cell) is about -65 to -80 dBm

Result: Worst C/I due to interference ( no dominant cell)

The solution to Interference, C/I,BER issue (1)

Interference Issue Solution

Serious interference due to Co-channel or

Adjacent channel

Adjust cell frequency or adjust

coverage

Serious interference due to feeder or Arrester Problem

Check whether the Feeder and

antenna tightening, or direct

�� !#

Problem antenna tightening, or direct

replacement its.

The solution to Interference,C/I,BER issue (1)

C/I Issue Solution

Worst C/I due to poor coverage

Improve coverage by adjusting

antenna azimuth and downtilt or

add new sites

Worst C/I to interference Ensure the interference source

�� !$

Worst C/I to interferenceand solution as interference

solution.

The solution to Interference,C/I,BER issue (1)

BER Issue Solution

Worst BER due to poor coverage

Improve coverage by adjusting

antenna azimuth and downtilt or

add new sites

Worst BER due to interference Ensure the interference source

�� !%

Worst BER due to interferenceand solution as interference

solution.

Worst BER due to Transmission Checking transmission alarm in

M2000

Worst BER to TRX At first check equipment alarm in

M2000,ensure which TRX is

problem

Handover Issues

What is…

� Handover procedure in network?

� Handover Um signaling flow?

� Purpose of Handover Analysis in DT?

��

� Purpose of Handover Analysis in DT?

Neighbor Cell_1

Serving Cell

Handover Procedure

Uplink MR (Measured by BTS)

•RXLEV Uplink•RXQUAL Uplink•TA•Current BTS TX power

� MS in dedicated mode will continuously perform

Neighbor Cell2

��

Neighbor Cell2

��"&

Downlink MR (Measured by MS)

•Downlink RXLEV(Sever)•Downlink RXQUAL(Sever)•RXLEV_NCELL(n) on the 6 best neighboring cells (+BSIC)

BSC

will continuously perform measurements on servingand neighbor cells.

�Measurement Reports are sent to BSC and used in the handover algorithm.

� Serving BSC decides whether a handover is necessary and send HO command

Serving Cell

Handover signaling on Um(TEMS Message)

BCCH of Neighbors

to be measuredServing Cell:DL DTX is ONRxLev(sub) is -109+ 62 =--49dBmRxQual (sub) is 0

Tell MS how to access to Target TCH Channel

Target cell Description

Target channel DescriptionChannel Type, Timeslot

TSC RF hoppingMAIO, HSN

�� "�

RxQual (sub) is 0

The RxLev ofNeighbors

MAIO, HSN

Inter cell Synchronous Handover

Speech version: EFR

Handover Complete �Handover Success!!!

Only after SABM & UA in Layer2 Message, handover success!

The purpose of handover analysis in DT is

� understand the wireless handover performance of network.

� find out whether the handovers are healthy in this network.

� what is typical handover failure in this network.

� find out whether neighbor audit work is needed in this network.

The purpose of Handover Analysis

��

� find out whether neighbor audit work is needed in this network.

To make optimization of HSR, the most effective way is based on traffic

analysis, combining DT events, neighbor audit, and data configuration

audit together.

��"

Handover Types

� Different handover types by network topology

� Different handover types by algorithm

� PBGT handover

� Quality handover

��

� Quality handover

� Edge Handover

� Intracell Handover

� Other types of handover

Handover Types(Network Topology)

Operator

MSC MSC

BSC BSC BSC BSC

��

� Case1 Intra cell HO

� Case2 Synchronous Inter cell HO

� Case3 Asynchronous Inter cell HO

� Case4 Inter BSC HO

� Case5 Inter MSC HO

��""

CELL CELL CELL CELL

Case 1

Synchronous

Case 2Asynchronous

Case 3Case 4 Case 5

CELL CELL CELL CELL

BTS BTS BTS BTS BTS BTS

Handover Types(Algorithm)

� In DT, the most common handover

types happens in following order of

priority

� TA

� RxQuality

OM Forced HO

Directed Retry

TA Emergency HO

Bad Quality HO

Edge HO

Layer HO

�� "'

� RxQuality

� RxLevel

� PBGT

� OL&UL HO

Bad Quality HO

Rapid Level Drop HO

Load HO

Interference HO

Layer HO

PBGT HO

Fast Moving MS HO

Overlay/Underly HO

� PBGT HO Exp:

When:

RXLEV_NCELL(n) – (RXLEVEL+

PWR_DIFF) > HO_MARGIN

MS is handed over to the neighboring cell .

� HO_MARGIN is usually set to 3 to 6 dB.

PBGT Handover

ServingCell

TargetCell

RXLEV_NCELL(n)

RX LEVEL + PWR_DIFF

Power-budgetPBGT HO

HO_MARGIN > 0

��

� HO_MARGIN could be increased to reduce number of handovers. HO_MARGIN should be decreased if faster handover decision is wanted.

� PBGT Handover is considered as most healthy handover in a network.

��"#

Distance

A typical PBGT HO

Quality Handover Exp:

When:

DL RxQuality >= DL Quality HO

Threshold

handover caused by DL RxQuality takes place.

When:

UL RxQuality >= UL Quality HO

Quality Handover

��

UL RxQuality >= UL Quality HO

Threshold

handover caused by UL RxQuality takes place.

� DL&UL Quality HO Thresholds are generally set to 6.

UL Quality HO can’t be monitored in DT.

��"$

Handover was performed to a better quality

cell just after experiencing quality problems.

EDGE Handover

Edge Handover Exp:

When:

DL RxLevel < Edge HO DL

RX_LEV Threshold

handover caused by DL RxLevel takes place.

When:

�� "%

When:

UL RxLevel < Edge HO UL

RX_LEV Threshold

handover caused by UL RxQuality takes place.

UL EDGE handover can’t be monitored in DT.

Handover was performed to the cell with

higher downlink Rxlev.

Intracell Handover Based on Interference

� The Intra–cell Handover feature aims to maintain good quality by performing a handover to a new channel within the same cell when uplink or downlink interference is detected.

�� '(

� Interference is defined by bad RxQual and high enough RxLEV.

� Intracell HO also can be triggered by:

• Rate change between Full rate and Half rate

• Handover between overlaid and underlaid subcell. An example of intracell handover after

experiencing quality problems.

Other types of handover are not easy to judge or not easy to encounter

in DT test, for example :

�TA handover

� Directed Retry

� Load handover

� Rapid Level Drop HO

Other types of handover

��

� Rapid Level Drop HO

� Fast Moving MS HO

��'&

For analysis of different types of handover or handover caused by uplink, it is recommended by traffic analysis or single-user signaling tracing.

Handover Issues

What is …

�Dragged Handover

�Power Control Effect

�Ping–Pong Handover

��


�Missing Neighbor Relation

�Fake Neighbor

�Handover Failure

Dragged Handover

There will be such cases that you will notice handover process taking

place a little late, which is called dragged handover.

� First thing to check will be handover margins between the neighbors. If margins for level, quality or power budget handovers are not set correctly, If margins are too much, handover will happen late, vice

�� '

versa. A Quality handover

should happen earlier

� Dragged handover events often occur after a GSM serving cell loses dominance for a significant time period.

Dragged Handover often cause Call

Drop or Handover Failure.

Power Control Effect

� Power Control Effect sometimes

may mislead us, you might think

that handover is happening too

late between two neighbors.

� When the call is continuing on a

timeslot that belongs to

TCHTRX, power control feature

will try to reduce output power

Power control

�� '!

as much as possible until a

quality problem occurs. That’s

why you will see serving cell

signal level is less than

neighbor’s level. It looks less

but in reality, the signal level on

BCCH TRX is still higher than

neighbors broadcasting level.

Ping-pong Handover

Ping-pong handovers occur when the MS is handed over from one cell to

another but is quickly handed back to the original cell.

� The shot shows two ping-pong handovers displayed on the map along with the Servering CI attribute. The first ping-pong handover is from cell 12424 to cell 12368 and back and the second is

�� '"

Ping-pong HO

and back and the second is from cell 12424 to cell 12366 and back. Changes in the value of the CI is shown below the route. It can be clearly visualized by lines to cells display.

� For most cases, Ping-pong Handover is caused by no dominant cell. There was a handover back to cell 12366 after the second ping-pong handover, but this was outside of the defined window. The change in dominance after the handover was 9dB, which represents a much healthier handover.

Missing Neighbor Relation

If a handoff is not performed to a neighbor cell that seems to be best

server, there is a possibility of a missing neighbor relation. This will

happen with sudden appearance of strong cell in the neighbor list

just after a handover.

� The shot shows after second handover in the red box, a much stronger Serving Cell

�� ''

stronger Serving Cell appears. ( suspect there might be missing neighbor in the 1st HO attempt)

� At this time Neighbor audit should be performed.

� Sometimes you will see a good

handover candidate in the

neighbor list but handover will

not take place and call will drop.

� Although that overshooting cell

with a very good signal level

Fake Neighbor Relation

��

with a very good signal level

appears in neighbor list, in reality

it is not. Just because the

serving cell has another

neighbor cell use same with the

same BCCH&BSIC ,so the

measurement of the

overshooting cell appears in the

list.

��'#

Handover Failure: Handover attempt was failed and the call returned back to its

all channel.

Handover Failure

Target Cell is � BCCH is 13� BSIC is 65Target channel is

��

Handover Failure

��'$

Target channel is � 900M RF hopping Channel. � Half Rate� MA list is 1, 17, 18, 19, 20, 21, 22, 23, 24� MAIO is 4, HSN is 31, � TSC is 5.� Channel mode is AMR(SV3)

The handover has not successfully completed yet!

Handover Failure is caused by T200 ExpiredAnother example: Excessive Number of Handover

Failure due to Hardware Problem

Proposal of Handover Issue

�Dragged Handover


�Missing Neighbor Relation

�Handover Failure

��

�Handover Failure

Solutions of Handover Issues

Issue Proposal

Dragged Handover

�Check if the parameter of handover, such as: PBGT, Quality, Interference, Edge

handover threshold, and P/N Value is set too high.

� Check if there is no dominant coverage. Referring to the solution of Low Coverage.

� Check if the traffic volume of target cell is high or has congestion at measuring time.

Ping-pong Handover

� Check if there is hardware problem. Referring to hardware checking guide

� Check if there is no dominant coverage. Referring to the solution of Low Coverage.

�� #(

Ping-pong Handover � Check if the parameter of handover, such as: PBGT, Quality, Interference, Edge

handover threshold, and P/N Value is set too low .

� Check if there is overlapping coverage area, which may also cause ping-pong

handover.

Missing Neighbor� Neighbor Audit. Check if there is neighbor missing according to data configuration in

OMC.

Handover Failure

� Find out the cause of Handover failure form Um signaling flow from Layer2 and

Layer3 Message.

� Check if the HSR between source and target cell is low. If it is, find the root cause of

handover failure reasons by traffic statistic analysis.

www.huawei.com

Thank You

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Documents

2 DriveTest Analysis Ver1-Libre