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HandoverHandover

Huawei Wireless Training Department

Contents

Summary of Handover(HO)

HO Algorithm Flow

HO Data Configuration

HO Signaling Flow

Summary of HO

Purpose of HO

Classification of HO

Summary of HO—Purpose of HO

Purpose of HOPurpose of HOTo keep moving MS continuous communicationTo keep moving MS continuous communicationTo improve network service performanceTo improve network service performance

To reduce the call drop rateTo reduce the call drop rate

To reduce the congestion rateTo reduce the congestion rate

Classification of HO: according to different HO Classification of HO: according to different HO triggering conditions triggering conditions

1.Emergency HO1.Emergency HOTA Emergency HOTA Emergency HO

Bad quality(BQ) Emergency HO Bad quality(BQ) Emergency HO

Rapid signal drop(RSD) Emergency HORapid signal drop(RSD) Emergency HO

Interference Emergency HO Interference Emergency HO

2.Load HO2.Load HO

3.Normal HO3.Normal HO Margin HOMargin HO

Hierarchical HOHierarchical HO

PBGT HOPBGT HO

4.Speed-sensitive HO (Fast moving HO)4.Speed-sensitive HO (Fast moving HO)

5.Over-layer/under-layer HO5.Over-layer/under-layer HO

Summary of HO—Classification of HO

HO Algorithm Flow

HO Algorithm Flow

General HO flow

Measurement report preprocessing

Penalty processing

Basic sequencing of cells and adjustment of network characteristics

HO judgement

General Flow of HO Algorithm

M.R. preprocess

penalty processing

Basic sequencing

Adjustment of network

characteristics

HO judgement

TA emergency HO

BQ emergency HO

RSD emergency HO

Interf. emergency HO

Load HO

Margin HO

Hierarchical HO

PBGT HO

Call control program

OM forced HO

Direct retry

Over-layer/under-layer HO

Fast moving HO

HO Algorithm FlowHO Algorithm Flow

HO algorithm flow

General HO flow


Penalty processing


HO judgment

Measurement Report Preprocessing

Serving cell Neighbour cell

The downlink measurement report of the neighbour cell (BCCH)

The downlink measurement report of the serving cell

The uplink measurement report of MS

Measurement Report (MR)----Including two parts: the uplink measurement report and the downlink measurement report Uplink: the measurement report is obtained from BTS of the serving cell, and includes the uplink receiving signal level (ULRxLev) and the uplink receiving signal quality (ULRxQal) for MS, and BTS_power. Downlink: the measurement report is obtained from MS and is sent to BTS, and includes the downlink receiving signal level (DLRxLev)and the downlink receiving signal quality (DLRxQal) for the servingcell, the downlink receiving signal levels for the neighbour cells (NCellRxLev), and MS_power, as well as the Time advance (TA), etc.



Period of measurement report

The measurement report is sent to BTS in SACCH uplinkThe measurement report is sent to BTS in SACCH uplink

1.The interval is 470ms/per time when MS is on SDCCH1.The interval is 470ms/per time when MS is on SDCCH

2.The interval is 480ms/time when MS is on TCH2.The interval is 480ms/time when MS is on TCH

12TCH12TCH 12TCH12TCH1SACCH1SACCH 1 idle1 idle

480ms480ms 4 TCH multi-frames4 TCH multi-frames


Missing MR processingMissing MR processing•Every time BSC receives a measurement report, Every time BSC receives a measurement report,

there will be an update to the basic sequencing of cells.there will be an update to the basic sequencing of cells.

•As BTS may fail to receive the measurement reportAs BTS may fail to receive the measurement report

from MS, so before the sequencing updating, BSC needsfrom MS, so before the sequencing updating, BSC needs

to recover the missing measurement report according toto recover the missing measurement report according to

Filter Data TableFilter Data Table. If the missing MR amount is within the . If the missing MR amount is within the

allowed range, then recover the missing MRs according allowed range, then recover the missing MRs according

to the algorithm.to the algorithm.

How to recover a MR?How to recover a MR?

MR MR MR MR MR

Measurement report No. n

Measurement report No. n+4

Continuous MR flow


How to filter the measurement report?How to filter the measurement report?

Filter----Average several continuous MR.Filter----Average several continuous MR.

MR MR MR MR MR MR

Continuous MR flow


Flow of HO Algorithm

General HO flow


Penalty processing

Basic sequencing of cells and

adjustment of network characteristics

HO judgment

Penalty Processing

————There are altogether four types of penalty processingThere are altogether four types of penalty processing

1. Penalty on the target cell when a HO fails.1. Penalty on the target cell when a HO fails.

2. Penalty on the original serving cell when an emergency HO is perfo2. Penalty on the original serving cell when an emergency HO is perfo

rmed.rmed.

3. Penalty on the other non-layer4 cells after a fast moving HO is perfo3. Penalty on the other non-layer4 cells after a fast moving HO is perfo

rmedrmed4. A second HO is prohibited 4. A second HO is prohibited within the penalty time after a over-layer/within the penalty time after a over-layer/under-layer HO fails.under-layer HO fails.

Penalty Processing

1. Penalty on the target cell:1. Penalty on the target cell:Punish the target cell where a HO fails to avoid MS to select this cell again in another HO judgment and fail again.

BTS

HO failure

BSC

Cell A

Cell D

BSC gives corresponding signal level penalty on cell DBSC gives corresponding signal level penalty on cell D

2. Penalty on the serving cell:2. Penalty on the serving cell:

Punish the original serving cell after TA\BQ\interf. HO, to avoid it to be handed over tPunish the original serving cell after TA\BQ\interf. HO, to avoid it to be handed over t

o the original cell again and cause ping-pang HO.o the original cell again and cause ping-pang HO.

BTS

BQ HO

BSC

Cell A

Cell D

In cases of HO from cell A to cell D due to poor quality, In cases of HO from cell A to cell D due to poor quality, punishing the original serving cell (cell A)punishing the original serving cell (cell A)

Penalty Processing

3.3. Give penalty to all non-layer4 Give penalty to all non-layer4 neighbor cellsneighbor cells after MS is hand after MS is handed over to a layer4 cell(Umbrella cell) by fast moving HO, to keeed over to a layer4 cell(Umbrella cell) by fast moving HO, to keep MS staying in the umbrella cell and avoid frequent HO.p MS staying in the umbrella cell and avoid frequent HO.

Penalty Processing

Macro cell

Back? No way!Back? No way!

Umbrella

Micro cell

4.4. A second over-layer/under-layer HO is prohibited within the pen A second over-layer/under-layer HO is prohibited within the penalty time after an over-layer/under-layer HO failsalty time after an over-layer/under-layer HO fails

Penalty Processing

Under-layer

Over-layerNo second No second

attempt attempt after a failed after a failed

HO!HO!

HO Algorithm Flow

General HO flow


Penalty processing


HO judgment

Basic Sequencing of Cells and Adjustment of Network Characteristics

Basic sequencing of cells and adjustment of network characteristics Basic sequencing of cells and adjustment of network characteristics

are major parts of the HO judgment. Sequencing is made by 16bits are major parts of the HO judgment. Sequencing is made by 16bits

algorithm. The serving cell and the candidate neighbor cells will be algorithm. The serving cell and the candidate neighbor cells will be

listed in a cell list according to their 16bits value. The sequencing listed in a cell list according to their 16bits value. The sequencing

process includes:process includes:

M ruleM rule

K ruleK rule

16bits sequencing16bits sequencing

I. M judgment:I. M judgment:

According to the min downlink receiving level and the min receiving level offset of the According to the min downlink receiving level and the min receiving level offset of the

reportedreported

neighbor cell, judge whether the cell is qualified as a candidate neighbor cell to be put neighbor cell, judge whether the cell is qualified as a candidate neighbor cell to be put

into the cell list for handover.into the cell list for handover.

M rule: only the cells with receiving signal level satisfy the following conditiM rule: only the cells with receiving signal level satisfy the following conditi

ons can be put into the candidate cell list. ons can be put into the candidate cell list.

For serving cell: For serving cell: RXLEV (o) >MSRXMIN(o) + MAX(0,Pa(o))RXLEV (o) >MSRXMIN(o) + MAX(0,Pa(o))

For neighbour cell: For neighbour cell: RXLEV(n) > MSRXMIN(n)+ MAX(0,Pa(n)) + OFFSETRXLEV(n) > MSRXMIN(n)+ MAX(0,Pa(n)) + OFFSET


II. K rule:

The cells surviving from M rule, including the serving cells The cells surviving from M rule, including the serving cells

and candidate neighbor cells, are sequenced according to and candidate neighbor cells, are sequenced according to

their receiving signal level which is actually a part of 16bits their receiving signal level which is actually a part of 16bits

rule.rule.



III. 16bits ruleIII. 16bits rule

Both the serving cell and the neighbor cell have their own 16bits value. Both the serving cell and the neighbor cell have their own 16bits value.

The smaller the value is, the higher the priority and the position is in The smaller the value is, the higher the priority and the position is in

the cell list.the cell list.

The 1st-3rd bits:The 1st-3rd bits: bit value is decided according to the cell signal level. bit value is decided according to the cell signal level.

The value result of max. 6 candidate cells and 1 serving cell according The value result of max. 6 candidate cells and 1 serving cell according

to the level ranges from 000~110, the value for the cell with the to the level ranges from 000~110, the value for the cell with the

strongest signal level is 000.strongest signal level is 000.

16 9101112131415 12345678


The 4th bit:The 4th bit: bit value is decided by inter-cell HO hysteresis. bit value is decided by inter-cell HO hysteresis.

The 4The 4thth bit of the serving cell is always 0, bit of the serving cell is always 0,

The receiving level of the neighbor cell > The receiving level of the The receiving level of the neighbor cell > The receiving level of the

serving cell + Inter-cell HO hysteresis, set to 0.serving cell + Inter-cell HO hysteresis, set to 0.

The receiving level of the neighbor cell < The receiving level of the The receiving level of the neighbor cell < The receiving level of the

serving cell + Inter-cell HO hysteresis, set to 1.serving cell + Inter-cell HO hysteresis, set to 1.

Note: In PBGT HO, if inter-cell hysteresis is larger than PBGT thresNote: In PBGT HO, if inter-cell hysteresis is larger than PBGT thres

hold, then inter-cell hysteresis will replace PBGT threshold.hold, then inter-cell hysteresis will replace PBGT threshold.

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The 5th-10th bits:The 5th-10th bits: bit value is decided according to their pos bit value is decided according to their pos

ition in Huawei hierarchical network structure.ition in Huawei hierarchical network structure.

When the signal level of the neighbor cell or the serving cell When the signal level of the neighbor cell or the serving cell

is lower than the hierarchical HO threshold(hysteresis), shieis lower than the hierarchical HO threshold(hysteresis), shie

ld it and set all bits to 0).ld it and set all bits to 0).

Huawei network can be divided into 4 layers and each layer Huawei network can be divided into 4 layers and each layer

can be further divided into 16 different priorities. So there arcan be further divided into 16 different priorities. So there ar

e 64 different priorities in Huawei hierarchical network.e 64 different priorities in Huawei hierarchical network.

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Hierarchical network structureHierarchical network structure

GSM900 Cell

Micro Cell

Umbrella Cell GSM 900

GSM1800 GSM1800GSM1800

GSM 900 GSM 900 GSM 900

GSM900GSM900

GSM1800GSM1800

GSM900 GSM900

GSM1800 GSM1800

GSM1800 Cell



The 11th bit:The 11th bit: bit value is decided by cell load bit value is decided by cell load

Serving cell: if Load>= Start threshold of load HO, set to 1, Serving cell: if Load>= Start threshold of load HO, set to 1,

otherwise set to 0.otherwise set to 0.

Neighbor cell: if Load>=receive threshold of load HO, set to 1, Neighbor cell: if Load>=receive threshold of load HO, set to 1,

otherwise set to 0.otherwise set to 0.

Refer to Load HO Data Table for the start threshold and receive Refer to Load HO Data Table for the start threshold and receive

threshold of load HO.threshold of load HO.

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The 12th and 13th bits:The 12th and 13th bits: bit value is decided by co-BSC/MSC adjust bit value is decided by co-BSC/MSC adjust

mentment

Serving cell: always 0Serving cell: always 0

Neighbor cell: if co-BSC/MSC with the serving cell, set 12/13 to 0, oNeighbor cell: if co-BSC/MSC with the serving cell, set 12/13 to 0, o

therwise set to 1, 12th bit is for BSC, 13th bit is for MSC.therwise set to 1, 12th bit is for BSC, 13th bit is for MSC.

When the signal level from the neighbor cell or the serving cell is lower thaWhen the signal level from the neighbor cell or the serving cell is lower tha

n the hierarchical HO threshold( including hysteresis) or co-BSC/MSC adjun the hierarchical HO threshold( including hysteresis) or co-BSC/MSC adju

stment is not allowed, shield them and set 12/13 to 0. stment is not allowed, shield them and set 12/13 to 0.

16 9101112131415 12345678


The 14th bit:The 14th bit: Hierarchical HO threshold adjustment bit Hierarchical HO threshold adjustment bit

Serving cell: The receiving level >= hierarchical HO threshold - hierServing cell: The receiving level >= hierarchical HO threshold - hier

archical HO hysteresis, set to 0. Otherwise set to 1, and meanwhile,archical HO hysteresis, set to 0. Otherwise set to 1, and meanwhile,

the 13 the 13thth, 12, 12thth and 10 and 10thth—5—5thth bits are set to 0 bits are set to 0

Neighbor cell: The receiving level >= hierarchical HO threshold + hNeighbor cell: The receiving level >= hierarchical HO threshold + hierarchical HO hysteresis, set to 0. Otherwise set it to 1, and meanierarchical HO hysteresis, set to 0. Otherwise set it to 1, and meanwhile, the 13while, the 13thth, 12, 12thth and 10 and 10thth—5—5thth bits are set to 0 bits are set to 0

16 9101112131415 12345678


The 15th bit:The 15th bit: bit value is decided by cell type bit value is decided by cell type

No matter it is a serving cell or a neighbor cell:No matter it is a serving cell or a neighbor cell:

For an extension cell, set to 1.For an extension cell, set to 1.

For a normal cell, set to 0.For a normal cell, set to 0.

The 16th bit: a reserved bitThe 16th bit: a reserved bit

16 9101112131415 12345678

HO Algorithm Flow

General HO flow


Penalty processing


HO judgment

HO Judgment OrderHO Judgment Order

Initializing

M rule

K rule

16bits rule

Emergency HO judgment

Load HO judgment

Normal HO

Fast moving HOHierarchical HO

PBGT HO

Send HO command

Send HO command

Send HO command

Over-layer/under-layer HO

Margin HO

Forced HO Direct re-try

HO JudgmentHO Judgment

• Types of HO Judgment:Types of HO Judgment:

Emergency HO----TA, BQ, Interf. RSDEmergency HO----TA, BQ, Interf. RSD

Load HOLoad HO

Normal HO----margin HO, hierarchical HO and PBGT HNormal HO----margin HO, hierarchical HO and PBGT H

OO

Fast moving HOFast moving HO

Over-layer/under-layer HOOver-layer/under-layer HO

Emergency HOEmergency HO

TA HO:TA HO:

TA of the serving cellTA of the serving cell is bigger than emergency HO TA limit is bigger than emergency HO TA limit

BQ HO:BQ HO:

1. 1. The average value of the uplink quality of the serving cell is bigger thanThe average value of the uplink quality of the serving cell is bigger than the uplink the uplink

quality limit of emergency HOquality limit of emergency HO

2. The average value of the downlink quality of the serving cell within is bigger than2. The average value of the downlink quality of the serving cell within is bigger than

the downlink quality limit of emergency HOthe downlink quality limit of emergency HO

Requirements for the target cell (same for the two types of HO):Requirements for the target cell (same for the two types of HO):

Select the neighbor cells with highest position(lowest 16bits value) Select the neighbor cells with highest position(lowest 16bits value)

except the serving cell.except the serving cell.


RSD HO:RSD HO:Triggered upon detecting rapid signal drop during the call:Triggered upon detecting rapid signal drop during the call:

Level

Time MR1 MR2 MR3 MR4 MR5 MR6

{ { {

Requirements for the target cell:Requirements for the target cell: the target cell is in the highest the target cell is in the highest

position in the cell list.position in the cell list.


Interference HO:Interference HO: also classified as emergency HO, and triggered also classified as emergency HO, and triggered

when the receiving level is bigger than a certain value but the receiwhen the receiving level is bigger than a certain value but the recei

ving quality is worse than the quality threshold of interference HO.ving quality is worse than the quality threshold of interference HO.

Requirements for the target cell:Requirements for the target cell:

1. The target cell is in the highest position except the serving cell1. The target cell is in the highest position except the serving cell

2. The signal level of the target cell should be bigger than the hierar2. The signal level of the target cell should be bigger than the hierar

chical HO threshold + the hierarchical HO hysteresischical HO threshold + the hierarchical HO hysteresis

If there is no candidate cell other than the serving cell in the cell list,If there is no candidate cell other than the serving cell in the cell list,

and intra-cell HO is allowed, then start intra-cell HO. Otherwise, no and intra-cell HO is allowed, then start intra-cell HO. Otherwise, no

HO is performed.HO is performed.

Load HOLoad HO

Load HOLoad HOTo trigger load HO, 3 pre-conditions should be satisfied at the same time:To trigger load HO, 3 pre-conditions should be satisfied at the same time:The system signaling flow is less thanThe system signaling flow is less than load HO flow level threshold load HO flow level thresholdThe load of the cell needing HO is higher thanThe load of the cell needing HO is higher than load HO start threshold load HO start thresholdThe load of the cell receiving HO is lower thanThe load of the cell receiving HO is lower than load HO receive threshold load HO receive threshold

Requirements for the target cell:Requirements for the target cell: the receiving level should be bigger than the hierarchi the receiving level should be bigger than the hierarchi

cal HO threshold + hierarchical HO hysteresis. It should be in the highest position excecal HO threshold + hierarchical HO hysteresis. It should be in the highest position exce

pt the serving cell in the cell list.pt the serving cell in the cell list.

BTS

BSC

Normal HO

Margin HO:Margin HO:

1. The serving cell receiving signal level is already lower than the margin HO threshold1. The serving cell receiving signal level is already lower than the margin HO threshold2. Within the margin HO statistics time, for example 5 seconds, the time in which the 2. Within the margin HO statistics time, for example 5 seconds, the time in which the signal level of the serving cell lower than the margin HO threshold is longer than signal level of the serving cell lower than the margin HO threshold is longer than margin HO continuous time, for example 4 secondsmargin HO continuous time, for example 4 seconds3. The target cell ranks the highest in the cell list3. The target cell ranks the highest in the cell list

margin threshold

Normal HO

Hierarchical HO:Hierarchical HO:

1. hierarchical HO only exists between different layers or different priorities at the same layer, an1. hierarchical HO only exists between different layers or different priorities at the same layer, an

d there is no hierarchical HO between cells from the same layer and with the same priority.d there is no hierarchical HO between cells from the same layer and with the same priority.

2. The triggering condition is that the signal level of the neighbor cell is higher than the hierarchi2. The triggering condition is that the signal level of the neighbor cell is higher than the hierarchi

cal HO threshold + hysteresis, while there is no requirement for the level of the serving cell.cal HO threshold + hysteresis, while there is no requirement for the level of the serving cell.

3.The neighbor cell ranks higher than the serving cell and has higher priority than the serving cell 3.The neighbor cell ranks higher than the serving cell and has higher priority than the serving cell

4. P/N judgment is satisfied, for example, within 5 seconds, the time that the cell is in the first po4. P/N judgment is satisfied, for example, within 5 seconds, the time that the cell is in the first po

sition of the cell list is longer than 4 seconds.sition of the cell list is longer than 4 seconds.

Attention:Attention: from low priority→high priority, emergency HO, margin HO and hierarchical HO are from low priority→high priority, emergency HO, margin HO and hierarchical HO are

possiblepossible

from high priority→low priority, emergency HO and margin HO are possible, and from high priority→low priority, emergency HO and margin HO are possible, and

hierarchical HO is not.hierarchical HO is not.

PBGT HOPBGT HO

PBGT HO algorithm is based on path loss. PBGT HO algorithm looks PBGT HO algorithm is based on path loss. PBGT HO algorithm looks

for whether there is a neighbor cell with lower path loss and for whether there is a neighbor cell with lower path loss and

satisfying certain system requirements, and judges whether HO is satisfying certain system requirements, and judges whether HO is

necessary. PBGT HO brings the following advantages:necessary. PBGT HO brings the following advantages:

Solution for problems of cross-cell coverage.Solution for problems of cross-cell coverage.

Less times of dual band HO.Less times of dual band HO.

More flexible method for traffic distribution control.More flexible method for traffic distribution control.

Always offer users with the best service currently available.Always offer users with the best service currently available.

Reduce the overall network interference.Reduce the overall network interference.

Attention:Attention: the largest difference between it and other HO algorithms is----the largest difference between it and other HO algorithms is----

the triggering condition for PBGT is path loss instead of receiving power. the triggering condition for PBGT is path loss instead of receiving power.

To avoid Ping-pang HO,To avoid Ping-pang HO, PBGT only happens between cells from the same PBGT only happens between cells from the same

layer and with the same priority.layer and with the same priority.

PBGT HO

Triggering rule of PBGT HO:Triggering rule of PBGT HO:

The path loss of the neighbor cell is less than the serving cell’s bThe path loss of the neighbor cell is less than the serving cell’s b

y y

certain value which is called the PBGT HO thresholdcertain value which is called the PBGT HO threshold The neighbor cell ranks higher than the serving cell do in the celThe neighbor cell ranks higher than the serving cell do in the cel

l listl listMeeting P/N rule in PBGT HO statistics timeMeeting P/N rule in PBGT HO statistics time

Attention: PBGT is only available for TCH HO. Attention: PBGT is only available for TCH HO.

PBGT HOPBGT HO

Fast Moving HOFast Moving HO

Criteria:Criteria: Among Among the statistics cells,the statistics cells, if the actual number of cells if the actual number of cells

the MS past fast is equal to or more than fast moving cell actual the MS past fast is equal to or more than fast moving cell actual

number, then the MS will be handed over to the neighbor layer 4 number, then the MS will be handed over to the neighbor layer 4

cell.cell.

Macro cell

Over-layer/Under-layer HOOver-layer/Under-layer HO

Over-layer/under-layer cell:Over-layer/under-layer cell: able to realize tight frequ able to realize tight frequ

ency reuse in the under-layer subcell(inner circle) and widency reuse in the under-layer subcell(inner circle) and wid

e coverage in the over-layer subcell(outer circle)e coverage in the over-layer subcell(outer circle)

Cell A Cell B

Innerl circleOuter circle

InterferenceSignal

Over-layer/Under-layer HOOver-layer/Under-layer HO

Over-layer/under-layer cell:Over-layer/under-layer cell: division of inner circle and division of inner circle and

outer circle is decided by MS outer circle is decided by MS downlink receiving leveldownlink receiving level and and TA TA

valuevalue..

Summary of HO

HO Algorithm Flow


HO Signaling Flow

Major HO parameter configuration

HO data lookup process

HO Parameter ConfigurationHO Parameter Configuration

1.[HO Control Data Table]1.[HO Control Data Table]2.[Cell Description Data Table]2.[Cell Description Data Table]3.[Adjacent Cell Relation Table]3.[Adjacent Cell Relation Table]4.[Penalty Data Table]4.[Penalty Data Table]5.[Emergency HO Data Table]5.[Emergency HO Data Table]6.[Load HO Data Table]6.[Load HO Data Table]7.[Normal HO Data Table]7.[Normal HO Data Table]8.[Fast Moving HO Data Table]8.[Fast Moving HO Data Table]9.[Over-layer/under-layer HO Data Table]9.[Over-layer/under-layer HO Data Table]

1.[HO Control Data Table] -11.[HO Control Data Table] -1

HO Parameter ConfigurationHO Parameter Configuration

Parametername

Meaning Value range Recommended value

AllowcommonBSC/MSCadjustment

It means whether the 12th and 13th bits acts in the 16bit order.“Yes” means handover in the same BSC/MSC is preferred.“No” means that the 12th and 13th bits are shielded and set to“0”.

Yes, No Yes

Allowpenaltyprocessing

It determines whether to punish the destination cell ofhandover failure, or the original served cell of handover upontoo big TA or bad quality. The penalty measures can apply tocells in or out of the same BSC.

Yes, No No

Allow loadhandover

It determines whether to perform the handover to share trafficload. Load sharing can lower the channel assignment failureratio caused by cell congestion, so as to make evenerallocation of the service in respective cells, and lower the cellcongestion ratio, and improve network performance. It onlyapplies in the same BSC or to cells at the same level, withrespect to TCH.

Yes, No No

Allow fastmovingmicro cellhandoveralgorithm

It determines whether to handle the fast moving MS with thealgorithm. This algorithm enables fast moving MS hand over tomacro cell and lowers times of handover. It is onlyrecommended in special areas (such as a highway), to lowerCPU load. This algorithm should only be used in suitableconditions, and usually it is not applied.

Yes, No No


Major HO Parameter ConfigurationMajor HO Parameter Configuration

Parametername

Meaning Value range Recommendedvalue

RXLEV dropHO algorithmallowed

It means whether RSD emergency handoveralgorithm is allowed, handover the MS whichreceiving signal level is dropping quickly in advance toavoid potential call drop. This algorithm should beapplied in suitable conditions, and usually it is notused. To apply the handover algorithm, BSC musthave original measurement report.

Yes, No No

PBGT HOalgorithmallowed

It means whether PBGT handover algorithm isallowed. PBGT handover algorithm currently isprocessed on LAPD board. To avoid Ping-panghandover, PBGT handover is only performed betweencells at the same layer and with the same priority, andmeanwhile it is only triggered on TCH. PBGThandover algorithm can effectively avoid co-frequencyor adjacent frequency interference.

Yes, No Yes

Post-HO PWRpred. Alg.allowed

It means after a handover whether MS is to useproper predicted transmitting power to access the newchannel. This can reduce system interference andimprove service quality (this parameter acts in BSC).

Yes, No Yes


Parametername


BTS meas.report pre-processing

It means whether to perform measurement reportpreprocessing on BTS. “No” means preprocessing onBSC, when the two parameters of “Send originalmeasurement report” and “Send BS/MS power level”do not act. “Yes” means decreasing of Abis interfacesignaling and BSC load, and improvement of networkresponse time performance. The switch determineswhere to perform power control. When it is set to“Yes”, power control is performed at BTS side. When itis set to “No”, power control is performed at BSC side.When setting this parameter, first be clear whetherBTS supports the power control algorithm to set ornot.

Yes, No Yes



Parametername


Transferoriginal meas.report

It means whether to send the original measurementreport to BSC after measurement report preprocessingon BTS. When it is set to “Yes”, BTS sends not onlyprocessed measurement report but also originalmeasurement report to BSC.

Yes, No No

TransferBS/MS powerlevel

It means whether to send BS/MS power level from BTS toBSC. This function is used to view the effect of powercontrol on BTS. Meanwhile, when preprocessing isavailable, if BS/MS power level is not reported, the uplinkand downlink balance measurements will be affected,and handover types such as PBGT handover and over-layer/under-layer handover needing power compensationwill be abnormal.

Yes, No Yes



Parametername


Pre-processingmeas. reportfrequency

It indicates the time interval at which a measurement reportis preprocessed at BTS side and sent to BSC the Pre-processing measurement report. This parameter acts onlywhen “Measurement report pre-processing” is open. For 15:1link configuration, the report frequency should be as low asonce per second due to limited link resource. At this time, forhandover needing P/N judgment such as margin handover,inter-level handover, PBGT handover and over-layer/under-layer handover, it is necessary to shorten P/N judgment time,because P/N judgment time is correspondingly twice thenumber of measurement reports in the program, and whenthe measurement report frequency is lowered, the actualjudgment time of BSC is lengthened.

Twice persecond, Onceper second

According toconcreteconditions


2.[Cell Description Data Table] -12.[Cell Description Data Table] -1


Parametername

Meaning Valuerange

Recommendedvalue

Layer of thecell

Huwei hierarchical network structure is divided into 4 layers. 16priorities can be set for each layer, which provides enough roomof network planning for the operator to adapt to various complexnetworking environment. Normally, Macro layer is the major 900layer, Micro layer is the major 1800 layer, Pico is the 900 and1800 micro cell layer. The smaller layer value, the higher priority.

The1st~4th

layers

M900: the 3rd

layer，M1800: the 2nd

layer

Cell priority Each layer may have 16 priorities, used to control the handoverpriority between cells at the same layer. Usually priorities of cellsat the same layer are set the same. For cells at the same layer,the smaller the priority value, the higher the priority.

1~16priorities

1

Hierarchicalhandoverthreshold

It affects the value of the 14th bit in the 16bit, and it is also thelevel requirement on the target cell for interference handover,hierarchical handover and load handover. Then such levelshould be higher than hierarchical handover threshold +hierarchical handover hysteresis. The hierarchical handoverthreshold should be set >= Edge handover threshold + Inter-cellhandover hysteresis.

0~63dB 25

hierarchicalhandoverhysteresis

Works together with the hierarchical handover threshold. 0~63dB 3


Parametername


Speedpenaltyvalue

It is valid when the fast moving handover algorithm isopen. It is the signal level penalty value on the non-layer4 neighbor cells when MS moves fast and ishanded over to layer4 cell. The parameter is only validwithin the speed penalty time.

0~63dB 30

Speedpenaltyduration

It means that within this time, the penalty on the non-layer4 neighbor cells will be exerted after MS is handedover to layer4 cell by fast moving HO.

0~255seconds

40

Mindownlinkpower ofhandovercandidatecell

This is the min signal level requirement for all candidatecells in M rule. Too low configuration may easily causecall drops, while too high a configuration might turnhandover too hard to occur.

0~63db 15

2.[Cell Description Data Table] -22.[Cell Description Data Table] -2

3.[Adjacent Cell Relation Table] -13.[Adjacent Cell Relation Table] -1


Parametername


Adjacentcell ID

The index value of the adjacent cell. Case 1, if the adjacentcell module number is not the outer-BSC cell, then theadjacent cell ID value ranges 0~255. Case 2, if the adjacentcell module number is the outer-BSC cell, then the adjacentcell ID value ranges 0~799.

Min accesslevel offset

This offset is based on “Min downlink power of handovercandidate cell”. Different offsets can be defined for differentadjacent cells, and to enter the candidate cell list, thecorresponding adjacent cell receiving signal level must bebigger than the sum of “Min downlink power of handovercandidate cell” and “ Min. Access level offset”.

0~63db 0


Parametername


PBGThandoverthreshold

It means that PBGT handover is performed when thedifference between the target cell downlink path loss and theserving cell downlink path loss is bigger than PBGT handoverthreshold. When PBGT handover is open, and “Inter-cellhandover hysteresis” > “PBGT handover threshold(corresponding dB value)”, “Inter-cell handover hysteresis”takes place of “PBGT handover threshold” to act. . PBGThandover threshold also needs to be adjusted according tohandover performance statistics result and live network.

0~127,corresponding to --64~63dB

It is around 68 in thedensely populateddowntown, andaround 72 on theoutskirts.

Inter-cellhandoverhysteresis

Handover hysteresis between an adjacent cell and the servingcell. It is set to reduce “Ping-pang” HO. The hysteresis valuealso needs to be adjusted according to the handoverperformance statistics result and live network. Flexibleconfiguration of the value can effectively lead handover andtraffic between two adjacent cells.

0~63db It is around 4 in thedensely populateddowntown, andaround 8 on theoutskirts.

3.[Adjacent Cell Relation Table] -23.[Adjacent Cell Relation Table] -2


4.[Penalty Data Table] -14.[Penalty Data Table] -1

Parametername


HO failure cellstrenthpenalty

The signal level value in dB, to punish the target cellwhich has caused a HO failure due to problems such ascongestion , to prevent MS from a handover re-attemptto that cell again. This value is only valid within thepenalty time for handover failure.

0~63db 30

HO failurepenaltyduration

Penalty time on the corresponding target cell afterhandover failure

0~60 seconds 10

BQ HOstrengthpenalty

The signal level penalty value for the original servingcell, to avoid “Ping-pang” handover after emergencyhandover upon bad quality. It is only valid within thepenalty time for BQ HO.

0~63db 63

BQ HOpenaltyduration

Penalty time for the original serving cell after BQ HO. 0~60 seconds 10


4.[Penalty Data Table] -24.[Penalty Data Table] -2

Parametername


TA HOstrengthpenalty

The signal strength penalty value for the original serving cell,to avoid “Ping-pang” handover after TA emergencyhandover. It is only valid within the penalty time for tahandover.

0~63db 63

TA HOpenaltyduration

Penalty time for the original serving cell after TA emergencyhandover.

0~60Seconds 10

Under-layer/over-layer HOpenaltyduration

After a under-layer/overlayer handover failure (big circlehands over to small circle or vice versa), within certain time(this parameter configuration value) under-layer/over-layerhandover is forbidden for the same call.

0~16Seconds 10


5.[Emergency HO Data Table] -15.[Emergency HO Data Table] -1

Parametername


EmergencyTA HOthreshold

When TA≥ this value, emergency handover is triggered 0~63 bit period 63

EmergencyHO DL qual.threshold

The downlink receiving quality threshold for BQemergency handover. When frequency hopping or DTXis open, RQ becomes worse (normal phenomenon), thisvalue should be set to 70. The adjustment should alsobase on the current network quality and handoverstatistics. When triggering emergency handover, thefirst to select is the intercell handover, the intra-cellhandover is only triggered when there is no candidatecell and the intra-cell handover is allowed in the servingcell.

0~70,correspondingto BQ levels of0~7

60

EmergencyHO UL qual.threshold

The uplink receiving quality threshold for BQemergency HO.

correspondingto BQ levels of0~7

60



Parametername


Interf. HOUL qualitythreshold

Uplink receiving quality threshold in the serving cell forinterference handover. When frequency hopping or DTX isopen, RQ becomes worse (normal phenomenon), this valueshould be set to 60. The adjustment should also base on thecurrent network quality and handover statistics. Whentriggering interference handover. If the serving cell is in thefirst position and intra-cell handover is permitted, performintra-cell handover. Otherwise select the second candidatecell to perform inter-cell handover.

correspondingto BQ levels of0~7

50, interferencequality thresholdmust be better thanthe emergencyquality threshold

Interf. HODL qualitythreshold

Downlink receiving quality threshold in the serving cell forinterference handover.

0~70,correspondingto BQ levels of0~7

50



Parameter name


Interf. HOUL RxPWRthreshold

Min uplink receiving power threshold from the serving cellrequired for interf. HO, when interference handover istriggered if the uplink quality is worse than quality thresholdand at this time the uplink signal level is higher than the signalthreshold. When triggering interference handover, If theserving cell is in the first position in the cell list, and opensintra-cell handover, then start intra-cell HO. Otherwise selectthe second cell to perform intr-cell HO.

0~63db 25

Interf. HODL RxPWRthreshold

Min downlink receiving power threshold from the serving cellrequired for interf. HO.

0~63db 30



Parametername


FilterparametersA1~A8

Used for configuration of filter for rapid signaldrop judgment, and together with filter parameterB, they are 9 parameters for a filter. Thecorresponding formula is (in the program, A1~A8is configuration value minus 10 and B is thenegative configuration value):C1(nt)=A1×C(nt)+A2×C(nt-t)+A3×C(nt － 2t)+ …+A8×C(nt-7t)Where, C (nt) is the receiving signal level in theuplink measurement report of the serving cellsent at the time of nt. If C1 (nt) < B, and C (nt) isbelow the edge handover threshold, then thesignal level is considered to be of rapid drop.

0~20 10

Filterparameter B

Used for configuration of filter for rapid signaldrop judgment. Please refer to the explanationfor A1~A8 of filter.

0~255 0


6.[Load HO Data Table] -16.[Load HO Data Table] -1

Parametername


Load HO flowlevelthreshold

The pre-condition for load HO is that the system flow (signalingflow) is lower the threshold. This value can not be set too highbecause load handover upon max threshold may causeunexpected effect to the system.

0, 8~11 systemflow levels,correspondingto 0, 70, 80, 90and 95.

10

Load HO startthreshold

Load handover is triggered when the serving cell load is higherthan the threshold, i.e. TCH occupied in the cell has reachingthe corresponding percentage.

0~7 cell loadlevels,correspondingto 0, 50, 60, 70,75, 80, 85, 90

5

Load HO Rxthreshold

The Load threshold for the target cells that can accept usersfrom serving cell in load HO, i.e. when the TCHs under Idlemode in the neighbor cell is lower than the correspondingpercentage, the cell refuses to accept MSs from serving cellhanded over due to the load reason.

0~7,correspondingto 0, 50, 60, 70,75, 80, 85, 90

2


6.[Load HO Data Table] -26.[Load HO Data Table] -2

Parametername


Loadhandoverbandwidth

This configuration is related to the margin handoverthreshold. Load handover is only allowed when the MSreceiving level from the serving cell is within the range ofmargin handover threshold, margin handover threshold +load handover bandwidth.

0~63db 25

Graded loadHO cycle

When a cell is up to conditions for load handover, all callswithin the serving cell will send handover request at thesame time, this will cause abrupt increase on processorload, and under certain conditions this will cause thetarget cell congestion and result in call drops. Thereby,step by step load handover algorithm is used to controlhandover. The cycle is the time needed for handovers ofeach step.

1~60 seconds 10

Graded loadHO cycle

The whold load HO bandwidth will be divided into severalsubbands by this parameter.

1~63db 5


7.[Normal HO Data Table] -17.[Normal HO Data Table] -1

Parametername


Margin HOuplinkthreshold

During the statistics time, if the time in which the uplinkreceiving level is lower than the value is higher thancertain time called continuous time, margin handoverwill be performed. If PBGT handover is open,corresponding margin handover threshold will be setlower.

0~63db 25 (without PBGThandover, downtown),15 (single station onoutskirts), 15 (withPBGT handover,downtown)

Margin HOdownlinkthreshold

Downlink consideration for margin HO. 63db 30 (without PBGThandover, downtown),20 (single station onoutskirts), 20 (withPBGT handover,downtown)



Parametername


Marginhandoverstatistics time

It means that within the time statistics, if thetime in which the signal level is lower thanthreshold is higher than the continuous time,then margin HO is to be triggered.

1~16 seconds 5

Marginhandovercontinuoustime

See the above. 1~16 seconds 4



Parametername


PBGThandoverstatistics time

Statistics time for PBGT HO signal level judgment. 1~16 seconds 5

PBGThandovercontinuoustime

Continuous time for PBGT HO signal level judgment. 1~16 seconds 4



Parametername


Hierarchicalhandoverstatistics time

Statistics time for Hierarchical HO judgment 1~16 seconds 5

Hierarchicalhandovercontinuoustime

Continuous time for Hierarchical HOjudgment.

1~16 seconds 4


8.[Fast Moving HO Data Table]8.[Fast Moving HO Data Table]

Parametername


Fast movingcell meas.number

The cell sum P for judge whether MS is fast moving.The value, if too large, may cause abrupt increase ofsystem flow, while too small value may causeinaccurate judgment for fast moving MS.

1~10 3

Fast movingcell actualnumber

The cell sum N by which MS actually quickly passes. Ifwithin P cells that MS continuously past, the number ofcells by which the MS is judged to pass quickly is equalto or more than N, then the MS will be judged as a fastmoving MS.

1~10 2

Fast movingtime threshold

The time threshold (2r/v) determined by the cell radius(r) and moving speed (v). If the time in which MSpasses the cell is smaller than the threshold, then MS isjudged to quickly pass the cell.

0~255seconds

15


9.[Over-layer/under-layer HO Data Table] -19.[Over-layer/under-layer HO Data Table] -1

Parametername


U/O intensitydifference

BTS transmitting Power difference between innercircle and outer circle may cause MS receivingsignal intensity difference in inner circle and outercircle. The parameter indicates power compensationvalue for the inner circle, and it is usually antennaoutput power difference in dB between inner circleand outer circle. According to field measurement,multi-point measurement is necessary if the innercircle and outer circle use different antenna.

0~63db Set according to actualconditions



Parametername


Rx levelthreshold

Rx level hysteresis, TA threshold and TA hysteresisland this threshold jointly define inner circle area andouter circle area. It must be bigger than marginhandover threshold, and the recommended value is:margin handover threshold + signal intensitydifference between inner circle and outer circle.

0~63db 25

Rx levelhysteresis

Works with Rx threshold. 0~63db 5

TA threshold It must be bigger than TA emergency handoverthreshold.

0~63 bit period,with 1 bit periodcorresponding to0.55km

TA hysteresis Works with TA threshold. 0~63 bit period



Parameter name Meaning Valuerange

Recommendedvalue

U/O handoverstatistics time

P/N judgment statistics time for U/O HO judgment. 0~16seconds

5

U/O handovercontinuous time

P/N judgment continuous time for U/O HO judgment. 0~16seconds

4



Parametername


Assignoptimumlayer

In U/O ells, the following selection are available for TCHassignment: (1) The system judges according to themeasurement report on SDCCH and assign to the best cell.(2) Select the outer circle first for TCH assignment. (3)Select the inner circle first for TCH assignment. (4) Do notgive extra priority.

Systemoptimization,over-layer subcell,under-layersubcell, nopreferential

System optimization

Assign-optimumlevelthreshold

If system optimization is selected, estimate (interpolate,filter) current SDCCH level value through uplinkmeasurement value in the former SDCCH measurementreport, and compare with “ Assign-optimum Levelthreshold”, so as to assign outer or inner circle channel.If SDCCH is in the outer circle: margin handover threshold+ signal intensity difference between inner circle and outercircle + uplink and downlink balance allowance + SDCCHand TCH difference allowance. If SDCCH is in the innercircle: margin handover threshold + uplink and downlinkbalance allowance + SDCCH and TCH differenceallowance, for the time being. 25 is recommended for thetime being.

0~63dbm



Parametername


Intra-BSCintercell HOoptimumalgorithm

When the cell is configured into a U/O cell, there are twoprocessing methods for incoming handover request in BSC:(1) No special processing for channel assignment. (2) AddBCCH signal level value of the target cell in inter-cellhandover request message to BSC to make BSC allocateoptimum channel for MS from inner cell or outer cell.

Yes, No Yes

IncomingBSC HOoptimum layer

If there is a incoming BSC HO, and the target cell is a U/Ocell, then, this parameter will show which layer is prefered toprovide service fro the MS.

Outer circle,inner circle,none

None

HO Data ConfigurationHO Data Configuration

Major HO data configuration

HO data lookup process

1.[HO Control Data Table]1.[HO Control Data Table]2.[Cell Description Data Table2.[Cell Description Data Table3.[Adjacent cell Relation Table]3.[Adjacent cell Relation Table]4.[Penalty Data Table]4.[Penalty Data Table]5.[Emergency HO Data Table]5.[Emergency HO Data Table]6.[Load HO Data Table]6.[Load HO Data Table]7.[Normal HO Data Table]7.[Normal HO Data Table]8.[Fast Moving HO Data Table]8.[Fast Moving HO Data Table]9.[Over-layer/under-layer HO Data Table]9.[Over-layer/under-layer HO Data Table]

1.1.BA2BA2 table defines BCCH carriers of all defined neighbor cells, and they are sent to MS by table defines BCCH carriers of all defined neighbor cells, and they are sent to MS by

system message 5 on SACCH.system message 5 on SACCH.

2.MS reports BCCH carriers,BSICs and signal levels of the max. 6 neighbor cells which ha2.MS reports BCCH carriers,BSICs and signal levels of the max. 6 neighbor cells which ha

ve highest signal levels out of all the defined neighbor cells, and of the serving cell to BSS ve highest signal levels out of all the defined neighbor cells, and of the serving cell to BSS

(through measurement reports)(through measurement reports)

3.After pre-processing of measurement reports, BSC ascertains module numbers, cell nu3.After pre-processing of measurement reports, BSC ascertains module numbers, cell nu

mber and CGI of all neighbor cells through mber and CGI of all neighbor cells through Adjacent cell Relation TableAdjacent cell Relation Table and and Cell DescriptiCell Descripti

on Data Tableon Data Table (or (or Outer Cell Description Data TableOuter Cell Description Data Table) by the aid of BCCH carrier and BSIC.) by the aid of BCCH carrier and BSIC.

4.BSC performs HO judgment processes such as basic sequencing of cells (completed in 4.BSC performs HO judgment processes such as basic sequencing of cells (completed in

LAPD board),and it sends HO request messages carrying target cell CGI to MPU of BSC onLAPD board),and it sends HO request messages carrying target cell CGI to MPU of BSC on

ce finds suitable target.Then according to CGI, MPU ascertains the module number of the ce finds suitable target.Then according to CGI, MPU ascertains the module number of the

cell in cell in Cell Module Information TableCell Module Information Table..

5.MPU sends a HO request message to the module and counts ‘Outgoing HO request’ one 5.MPU sends a HO request message to the module and counts ‘Outgoing HO request’ one

time.time.

The process to Look for HO DataThe process to Look for HO Data

Summary of HO

HO Algorithm Flow


HO Signaling Flow

HO Signaling Flow

HO in BSC

HO in MSC

HO between MSCs

HO in BSC

Signaling FlowSignaling Flow

PrecautionsPrecautions

For the asynchronous HO, if MS still could not access the new cFor the asynchronous HO, if MS still could not access the new c

hannel after the target cell sends PHY INFO up to max times, the hannel after the target cell sends PHY INFO up to max times, the

target cell reports CONN FAIL IND to BSC, with the reason: HO atarget cell reports CONN FAIL IND to BSC, with the reason: HO a

ccess failure. After receiving the message, BSC starts the releasccess failure. After receiving the message, BSC starts the releas

e flow for the new channel in the target cell .e flow for the new channel in the target cell .

Attention: Max resending times of physical information*Radio link conneAttention: Max resending times of physical information*Radio link conne

ction timer > Time interval of ction timer > Time interval of EST IND~HO DETECT (120~180ms)EST IND~HO DETECT (120~180ms), to make , to make

full use of the physical information in case the link is unstable.full use of the physical information in case the link is unstable.

HO in BSC

Statistics counter pointsStatistics counter points

MS BTS(Source) BSC BTS(Target) MSC

Measurement Report

Measurement Report

T09++ Handover algorithm judges outgoing handover request (incoming handover request reaches) T12++

Channel Activation

Channel Activation ACK

Handover Command (Old FACCH)

Handover Access (New FACCH)

Handover Complete (New FACCH) T10++ T13++

RF Channel Release

Handover Performed

I ncomi ng handover request ti mes i n BSC

Outgoing handover requesttimes in BSC

Successful outgoing handover timesIn BSC

Successful incoming handover timesIn BSC

HO in BSC

HO formulaHO formula

HO success rate in BSC= —————————————Times of success inter-cell HO in BSC

Times of inter-cell HO request in BSC

Wireless HO success rate in BSC ＝—————————————

Wireless HO success rate >= HO success rate

HO in BSC

Times of success inter-cell HO in BSC

Times of inter-cell HO in BSC

HO in MSC

HO Signaling Flow

HO in BSC

HO in MSC

HO between MSCs

Sig

nalin

g

Sig

nalin

g

Flo

wF

low

HO in MSC

Channel Release FlowChannel Release Flow

HO in MSC

MS BTS(Source) BSC MSC BSC BTS(Target)

Measurement Report

Measurement Report

Handover Required T17++

Handover Request T14++

Channel ACT

Channel ACT ACK

Handover Request ACK

Handover Command

Handover Access

Handover Detect

Handover Complete

Handover Complete T15++

Clear Command (HO successful) T18++

RF Channel Release

Clear Complete

Times of outgoing handoverrequest between BSCs

Times of incominghandover request between BSCs

Times of successfulincoming handover between BSCs

Times of successfuloutgoing handover between BSCs

Sta

tistic

s co

un

ters

of H

O in

S

tatis

tics c

ou

nte

rs o

f HO

in

MS

CM

SC

HO in MSC

HO formulaHO formula

HO success rate in MSC=＝————————————————————

Times of success outgoing BSC HOs +

Times of success incoming BSC HOs

Times of outgoing BSC HO requests+

Times of incoming BSC HO requests

Wireless HO success rate in MSC ＝————————————————

Times of success outgoing BSC HOs +

Times of success incoming BSC HOs

Times of outgoing BSC HOs +

Times of incoming BSC HOs

HO in MSC

HO Between MSCs

HO signaling flow

HO in BSC

HO in MSC

HO between MSCs

HO Between MSCs

~ ~~ ~

MS MS

BSS1 MSCa MSCb

BSS2

VLRbRadio transmission signal measurement

HO REQ.Perform HO(MAP)

(Global target cell list)

(Global target cell IDglobal service cell IDchannel type)

HO REQUEST (PCM&Channel type)HO REQUEST ACKNOWLmargin Incl. New TCH and HON

Allocation HO number

Send HO report (HON.)Radio channel ack.(MAP) Incl. New TCH and HON

IAM

ACM HO COMMAND

HO CMD

Hnadover MS to new channel via original BSS

HO test HO DETECT

HO finish HO COMPLETE

BSS2 selects TCH to connect to PCM circuitMS enter target cell

Send end signal Send end signal(MAP)

CLEAR COMMANDRelease PCMD

CLEAR COMPLETE

ANS

Release (TUP/ISUP)

End signal(MAP)

Disconnect MSCa and MSCb

HO report

Mobile

Um A E B

A Um

HO Between MSCs

Signaling flow – Abnormal Signaling flow – Abnormal conditionsconditions

The following conditions will cause HO The following conditions will cause HO failure----failure----

MSC-B fails to identify the target cellMSC-B fails to identify the target cellMSC-B does not allow HO to the indicated MSC-B does not allow HO to the indicated target celltarget cellThe target cell has no channel available in itThe target cell has no channel available in itVLR-B has no HO number availableVLR-B has no HO number availableHO error or unsuitable data HO error or unsuitable data

HO Between MSCs—Subsequent HO FlowRoaming

E

MS

MSCa MSCbMSCb'

VLRbVLRb'

BSS2

BSS2'

Radio transmission signal measurementHO REQUIRED (target cell table)

Perform subsequent HO(MAP) (target cell ID, serving cell ID, MSC number)

Perform HO(target cell ID, serving cell ID, channel type)

HO REQUEST (PCM&Channel type)

HO REQUEST ACKNOWLmargin (including New TCH number and HO number)

Allocate HO number

Send HO report(HON)Radio channnel ack. (MAP) (includes New TCH number and HON)

IAM

ACM

Subsequent HO ack.

HO COMMAND HO DETECT

HO COMPLETESend end signal (MAP)

ANS

End signal (MAP)Release HO report Release HON

CLEAR COMMAND

CLEAR COMPLETERelease (TUP)

Cut physical connection between MSCa and MSCb

End signal (MAP)

Release (TUP/ISUP)Release HO report Release HON

Cut physical connection between MSCAa and MSCb'

~~ ~~

MS

HO Between MSCs—Subsequent HO Flow

Highway

MSC-AMSC-C

MSC-B MSC-C

Subsequent HO

HO Between MSCs

Statistics counter—same as HO in MSC, Statistics counter—same as HO in MSC, statistics is made by BSCstatistics is made by BSC

HO formula-- same as HO in MSCHO formula-- same as HO in MSC

1. There is no “HO request” information for HO in BSC, and all of the HO is analyzed an1. There is no “HO request” information for HO in BSC, and all of the HO is analyzed and processed in BSC. Once the target cell as required is found in the BSC, “Channel actid processed in BSC. Once the target cell as required is found in the BSC, “Channel activation” information is sent directly.vation” information is sent directly.

2. When the target cell is not in the BSC, BSC reports CGI numbers of the serving cell a2. When the target cell is not in the BSC, BSC reports CGI numbers of the serving cell and target cell, and HO cause to MSC through “Ho-Required”. When MSC finds that LAC nd target cell, and HO cause to MSC through “Ho-Required”. When MSC finds that LAC of the target cell is in the MSC, it sends “Ho-Request” to the BSC of the target cell, and tof the target cell is in the MSC, it sends “Ho-Request” to the BSC of the target cell, and the target BSC activates the target cell channel to complete the following procedure.he target BSC activates the target cell channel to complete the following procedure.

3.When MSC finds that the target cell LAC does not belong to the MSC, it will query its 3.When MSC finds that the target cell LAC does not belong to the MSC, it will query its “REMOTLAC Table” (including LAC and router address of the adjacent MSC), and send “REMOTLAC Table” (including LAC and router address of the adjacent MSC), and send “Prepare-HO” message to the target MSC-B according to the router address. The messa“Prepare-HO” message to the target MSC-B according to the router address. The message includes CGI of the target cell and indication whether to allocate HO number, etc. Acge includes CGI of the target cell and indication whether to allocate HO number, etc. According to the message, the target MSC-B sends “HO-Request” message to the target Bcording to the message, the target MSC-B sends “HO-Request” message to the target BSC-B after demanding HO number (unless it is not required in the indication) from VLR-SC-B after demanding HO number (unless it is not required in the indication) from VLR-B, and sends “Prepare-HO acknowledgement” to serving MSC after receiving “HO-RequB, and sends “Prepare-HO acknowledgement” to serving MSC after receiving “HO-Request acknowledgement”, to execute the following procedure.est acknowledgement”, to execute the following procedure.

Basic Flow of HO Signaling

Major differences:Major differences:

1. Inter-BSC HO transfers “HO-REQ” message through MSC, 1. Inter-BSC HO transfers “HO-REQ” message through MSC,

with CGI of the serving cell and target cell carried in the with CGI of the serving cell and target cell carried in the

message.message.

HO in BSC does not have any CGI in any message, it is HO in BSC does not have any CGI in any message, it is

handled inside BSC.handled inside BSC.

2. HO in BSC only sends “HO-Performed” to MSC upon 2. HO in BSC only sends “HO-Performed” to MSC upon completion of HO, and MSC is not involved before that time.completion of HO, and MSC is not involved before that time.

But in the inter-BSC HO, MSC is involved ever since the HO But in the inter-BSC HO, MSC is involved ever since the HO request .request .

HO in BSC and Inter-BSC HO

Thanks