Handover Algorithm (Complete and Detailed)

Huawei Handover Algorithm

HUAWEI TECHNOLOGIES CO., LTD.

Huawei Handover Algorithm(GSM BSS)

6/05/2009


Table of Contents

1 Overview .............................................................................7

1.1 Background Introduction .................................................................................................. 7

1.2 Introduction to the Principles of Handover Algorithms ...................................................7

1.2.1 Procedures Related to Handover Algorithms ...................................................................7

1.2.2 MR Processing .................................................................................................................8

1.3 Handover Decision Algorithms ...................................................................................... 11

1.3.1 High-Speed Railway Fast Handover .............................................................................. 11

1.3.2 Emergency Handover .....................................................................................................12

1.3.3 Enhanced Dual-Band Handover .....................................................................................12

1.3.4 Load Handover ...............................................................................................................12

1.3.5 Normal Handover ...........................................................................................................12

1.3.6 No Downlink Measurement Report Handover ...............................................................15

1.3.7 Penalty Processing..........................................................................................................16

1.3.8 Triggering Conditions of Penalty ...................................................................................18

1.3.9 Penalty Processing..........................................................................................................18

1.3.10 Basic Queuing ................................................................................................................ 19

1.3.11 Network Characteristics Adjustment ..............................................................................23

1.3.12 Forced Handover ............................................................................................................27

1.3.13 Handover Decision .........................................................................................................28

1.3.14 Emergency Handover .....................................................................................................28

1.3.15 TA Handover ..................................................................................................................28

1.3.16 Interference Handover ....................................................................................................30

1.3.17 Quick Level Drop Handover ..........................................................................................32

1.3.18 Bad Quality Handover ....................................................................................................34

1.3.19 Load Handover...............................................................................................................37

1.3.20 Normal Handover ...........................................................................................................39

1.3.21 Edge Handover ...............................................................................................................40

1.3.22 Fast-Moving Micro-to-Macro Cell Handover ................................................................ 42

1.3.23 Hierarchical Handover ...................................................................................................44

1.3.24 PBGT Handover .............................................................................................................45

1.3.25 Concentric Cell Handover ..............................................................................................49

1.3.26 Normal Concentric Cell Algorithm ................................................................................ 49

1.3.27 Enhanced Concentric Cell Algorithm .............................................................................49

1.3.28 AMR Handover ..............................................................................................................53

1.3.29 Handover from TCHF to TCHH ....................................................................................54

1.3.30 Handover form TCHH to TCHF ....................................................................................54

1.3.31 Better 3G Cell Handover ................................................................................................ 55

1.3.32 Directed Retry ................................................................................................................ 57

1.3.33 Handover in Single-Signaling /SDCCH State................................................................ 57


1.3.34 Handover Implementation ..............................................................................................57

2 Parameters Involved in the Algorithms................................... 58

2.1 Parameters detail description..........................................................................................58

2.1.1 Co-BSC/MSC Adj ..........................................................................................................58

2.1.2 SDCCH HO Allowed .....................................................................................................58

2.1.3 Penalty Allowed .............................................................................................................59

2.1.4 MS Power Prediction after HO.......................................................................................59

2.1.5 Power Level for Direct Try ............................................................................................60

2.1.6 Allowed MR Number Lost .............................................................................................60

2.1.7 RscPenaltyTimer ............................................................................................................61

2.1.8 UmPenaltyTimer ............................................................................................................61

2.1.9 CfgPenaltyTimer ............................................................................................................61

2.1.10 MR Preprocessing ..........................................................................................................62

2.1.11 Transfer Original MR .....................................................................................................62

2.1.12 Transfer BS/MS Power Class .........................................................................................63

2.1.13 Sent Freq of Preprocessed MR .......................................................................................63

2.1.14 Report Type ....................................................................................................................64

2.1.15 DtxMeasUsed .................................................................................................................64

2.1.16 Allowed MR Number Lost .............................................................................................65

2.1.17 Filter Length for SDCCH Level .....................................................................................65

2.1.18 Filter Length for TCH Level ..........................................................................................65

2.1.19 Filter Length for SDCCH Qual ......................................................................................66

2.1.20 Filter Length for TCH Qual............................................................................................66

2.1.21 Filter Length for TA .......................................................................................................67

2.1.22 Filter Length for Ncell RX_LEV ...................................................................................67

2.1.23 Penalty Level after TA HO .............................................................................................68

2.1.24 Penalty Time after TA HO(s) ..........................................................................................68

2.1.25 Penalty Level after BQ HO ............................................................................................69

2.1.26 Penalty Time after BQ HO (s) ........................................................................................69

2.1.27 Penalty Level after HO Fail............................................................................................70

2.1.28 Penalty Time after HO Fail(s) ........................................................................................70

2.1.29 Penalty on MS Fast Moving HO ....................................................................................71

2.1.30 Penalty Time on Fast Moving HO..................................................................................71

2.1.31 Quick Handover Punish Value ........................................................................................72

2.1.32 Quick Handover Punish Time ........................................................................................72

2.1.33 Inter-BSC SDCCH HO Allowed ....................................................................................72

2.1.34 Min DL Level on Candidate Cell ...................................................................................73

2.1.35 HOCdCellMinUpPwr .....................................................................................................73

2.1.36 Min Access Level Offset ................................................................................................ 74

2.1.37 K Bias .............................................................................................................................74

2.1.38 UTRAN Cell Type..........................................................................................................75


2.1.39 FDD REP QUANT.........................................................................................................75

2.1.40 Min RSCP Threshold .....................................................................................................76

2.1.41 Min Ec/No Threshold .....................................................................................................76

2.1.42 RSCPOff.........................................................................................................................77

2.1.43 EcNoOff .........................................................................................................................77

2.1.44 Inter-layer HO Threshold ...............................................................................................77

2.1.45 Inter-layer HO Hysteresis...............................................................................................78

2.1.46 Inter-cell Handover Hysteresis .......................................................................................78

2.1.47 Min Interval for TCH Hos..............................................................................................79

2.1.48 Min Interval for SDCCH Hos ........................................................................................79

2.1.49 Min Interval for Consecutive Hos ..................................................................................80

2.1.50 Min Interval for Emerg Hos ...........................................................................................80

2.1.51 MS Fast-moving Time Threshold...................................................................................81

2.1.52 Max Consecutive HO Times ..........................................................................................81

2.1.53 Forbidden Time after Max Times ...................................................................................82

2.1.54 Interval for Consecutive HO Jud. ...................................................................................82

2.1.55 DtxMeasUsed .................................................................................................................83

2.1.56 Max Resend Times of Phy Info ......................................................................................83

2.1.57 T3105 (10ms) .................................................................................................................84

2.1.58 No Dl Mr. HO Allowed ..................................................................................................85

2.1.59 Cons. No Dl Mr. HO Allowed Limit ..............................................................................85

2.1.60 No Dl Mr. Ul Qual HO Limit .........................................................................................86

2.1.61 TA HO Allowed..............................................................................................................87

2.1.62 TA Threshold ..................................................................................................................87

2.1.63 Interference HO Allowed ...............................................................................................87

2.1.64 RXQUAL1 .....................................................................................................................88

2.1.65 RXQUAL2 .....................................................................................................................88

2.1.66 RXQUAL3 .....................................................................................................................88

2.1.67 RXQUAL4 .....................................................................................................................89

2.1.68 RXQUAL5 .....................................................................................................................89

2.1.69 RXQUAL6 .....................................................................................................................90

2.1.70 RXQUAL7 .....................................................................................................................90

2.1.71 RXQUAL8 .....................................................................................................................90

2.1.72 RXQUAL9 .....................................................................................................................91

2.1.73 RXQUAL10 ...................................................................................................................91

2.1.74 RXQUAL11 ...................................................................................................................92

2.1.75 RXQUAL12 ...................................................................................................................92

2.1.76 RXLEVOff .....................................................................................................................92

2.1.77 Intracell HO Allowed .....................................................................................................93

2.1.78 Rx_Level_Drop HO Allowed.........................................................................................93

2.1.79 Filter Parameter A1–A8..................................................................................................93

2.1.80 Filter Parameter B ..........................................................................................................94


2.1.81 BQ HO Allowed .............................................................................................................94

2.1.82 DLQuaLimitAMRFR .....................................................................................................95

2.1.83 ULQuaLimitAMRFR .....................................................................................................95

2.1.84 DLQuaLimitAMRHR ....................................................................................................95

2.1.85 ULQuaLimitAMRHR ....................................................................................................96

2.1.86 DL Qual. Threshold ........................................................................................................ 96

2.1.87 UL Qual. Threshold ........................................................................................................ 97

2.1.88 BQ HO Margin ...............................................................................................................97

2.1.89 Load HO Allowed ..........................................................................................................97

2.1.90 System Flux Threshold for Load HO .............................................................................98

2.1.91 Load HO Threshold ........................................................................................................ 98

2.1.92 Load HO Step Period .....................................................................................................99

2.1.93 Load HO Step Level .......................................................................................................99

2.1.94 Load HO Bandwidth .................................................................................................... 100

2.1.95 Load Req. on Candidate Cell ....................................................................................... 100

2.1.96 Edge HO Allowed ........................................................................................................101

2.1.97 Edge HO UL RX_LEV Threshold................................................................................101

2.1.98 Edge HO DL RX_LEV Threshold................................................................................101

2.1.99 Edge HO Watch Time(s) .............................................................................................. 102

2.1.100 Edge HO Valid Time (s) ............................................................................................... 102

2.1.101 NC Edge HO Watch Time(s) ........................................................................................103

2.1.102 NC Edge HO Valid Time (s)......................................................................................... 103

2.1.103 MS Fast Moving HO Allowed ...................................................................................... 103

2.1.104 MS Fast-moving Watch Cells....................................................................................... 104

2.1.105 MS Fast-moving Valid Cells ........................................................................................104

2.1.106 PBGT HO Allowed ...................................................................................................... 105

2.1.107 PBGT HO Threshold.................................................................................................... 105

2.1.108 PBGT Watch Time (s) .................................................................................................. 106

2.1.109 PBGT Valid Time (s) .................................................................................................... 106

2.1.110 Intracell F-H HO Allowed ............................................................................................ 106

2.1.111 Penalty Time after AMR TCHF-H HO Fails(s)............................................................ 107

2.1.112 F2H HO th.................................................................................................................... 107

2.1.113 H2F HO th.................................................................................................................... 108

2.1.114 Intracell F-H HO State Time (s) ...................................................................................108

2.1.115 Intracell F-H HO State Time (s) ...................................................................................108

2.1.116 Outgoing-RAT HO Allowed......................................................................................... 109

2.1.117 Better 3G Cell HO Allowed ......................................................................................... 109

2.1.118 TDD Better 3G Cell HO Allowed ................................................................................110

2.1.119 RSCP Threshold for Better 3G CELL HO ...................................................................110

2.1.120 TDD RSCP Threshold for Better 3G CELL HO .......................................................... 110

2.1.121 Ec/No Threshold for Better 3G CELL HO ...................................................................111

2.1.122 3G Better Cell HO Valid Time ..................................................................................... 111


2.1.123 3G Better Cell HO Watch Time.................................................................................... 112

2.1.124 TDD 3G Better Cell HO Valid Time ............................................................................ 112

2.1.125 TDD 3G Better Cell HO Watch Time...........................................................................113

2.1.126 Inter-RAT HO Preference............................................................................................. 113

2.1.127 Inter-RAT HO Preference............................................................................................. 114

2.1.128 TDD Inter-RAT HO Preference.................................................................................... 114

2.1.129 HO Preference Threshold for 2G Cell .......................................................................... 115

2.1.130 TDD HO Preference Threshold for 2G Cell................................................................. 116


1 Overview

1.1 Background Introduction

The service area of the GSM is composed of the cells with continuous coverage. To enable the

users in move to communicate without interruption and to optimize the network performance, the

handover technique is introduced to the GSM system.

The handover in the GSM system involves the following entities: Mobile Station (MS), Base Station

Subsystem (BSS), and Mobile Switching Center (MSC). The MS and BTS in service measure the

uplink and downlink radio links respectively, assemble the measurement results into measurement

reports (MRs), and then send the MRs to the BSC. The handover algorithms in the BSC decide

whether to initiate handovers based on the measurement results and the actual network

performance. The algorithms also decide in which way to process the handover.

This document describes the technical aspects of handover in Huawei BSC6000 V900R008 in

terms of algorithm principles, applications, and parameters.

1.2 Introduction to the Principles of Handover Algorithms

1.2.1 Procedures Related to Handover Algorithms

The handover algorithms of the GSM system function in the following phases: measurement and

production of the MRs, MR processing, handover algorithm decision, and handover execution.

The measurement and the production of the MRs are performed by the MS andBTS. The MS measures and reports the downlink signal level of GSM cells,signal quality, and TA, whereas the BTS measures and reports the receive signallevel of the MS and its quality.

The MR processing is performed by the BSC (the BTS can perform the task if theprocessing functionality is assigned to the BTS). The BSC performs basicfunctions such as filtering and interpolation. The processed MRs are the basicinputs for the handover algorithms and serve as the basis for the handoveralgorithms taking decisions. The BSC select neighbor cells based on theBCCH/BSIC information in the downlink MRs. The cells with the sameBCCH/BSIC information are removed with only one neighbor cell is retained. If aneighbor cell is not found with respect to BCCH/BSIC, you can infer that theneighbor cell is illegal, and thus the measurement values are not processed.

The handover algorithms evaluate the candidate cells based on the factors suchas radio signal quality, MS speed, traffic load, and requirements from the telecomoperator, and then determine the target cells.

After the target cells are determined, the handover execution part performssignaling interaction and handles the handover failures, rollback, or otherexceptions and, if necessary, forwards the result to the handover decisionmodule and tries other candidate cells.

The following figure shows the procedures related to GSM handover algorithms.


Procedures related to handover algorithms

MS entering connectionstate

Measurement andproduction of MRs

MR processing

Algorithms makinghandover decision

Handover execution

MS entering newconnection state

Figure1

1.2.2 MR Processing

The MR processing involves interpolation processing and filtering processing. The processing

procedure of the MRs is as follows:


Processing procedure of the MRs

Start (processesMR)

MR Preprocessing enabled?

End

UL/DL DTX once enabled?

TCH measurement ofthe serving cell

(SUBSET scheme)

MR serial numbercontinuous?

Performs linear interpolationof the MRs and then insert

latest MR value

End

No

Yes

No

Insert latest MRvaluesNumber of lost MRs

(serving cell) is less thanthe value of Allowed MR

Number Lost?

Discard former MRvalues and insert latest

MR values

Number of validbuffered MRs smaller

than values of the filterlength parameters?

Yes

No

Filtering processingof MRs

Filter length parameters:

Filter Length for SDCCH LevelFilter Length for TCH LevelFilter Length for SDCCH QualFilter Length for TCH QualFilter Length for TAFilter Length for Ncell RX_LEVFilter Length for SDCCH MEAN_BEPFilter Length for TCH MEAN_BEPFilter Length for SDCCH CV_BEPFilter Length for TCH CV_BEPFilter Length for SDCCH REP_QUANTFilter Length for TCH REP_QUANT

Filter Length for SDCCH NBR_RCVD_BLOCKFilter Length for TCH NBR_RCVD_BLOCK

Specifies the contents to bereported and the period toprovide the preprocessing

report based on theconfiguration parameters

Configuration parametersof pre-processed MRs:

Enhanced MR?

Interpretation ofnormal MR

Interpretation ofenhanced MR

MR type:Enhanced MR and normal

MR

Yes

DtxMeasUsed is set to TRUE?NoYes

UL/DL DTX enabled?

Switch for controlling the valuedetermination method of MR:

DtxMeasUsed

Allowed MR Number Lost

Yes

YesNo

No

No

No

Yes


(FULLSET scheme)

Yes

TCH measurement ofthe serving celll

(SUBSET scheme)


(FULLSET scheme)

MR Preprocessing

Transfer Original MR

Transfer BS/MS Power Class

Sent Freq of Preprocessed MR


The processing of the MRs involves interpolation processing and filtering processing. The

processing can be performed either on the BSC side or on the BTS side. In the BSC6000 LMT, set

MR Preprocessing to Yes, then you can set the parameters Transfer Original MR, Transfer

BS/MS Power Class, and Sent Freq of Preprocessed MR. These parameters specify the

contents of the MRs to be provided and the period during which the MRs are provided. In this way,

the signaling throughput on the Abis interface and the CPU usage of the BSC can be decreased.

If the BTS reports the measurement result information, then the information is processed according

to the interpolation and filtering procedures.

If the BTS reports the pre-processed measurement result information, then the information is used

for handover decision directly. Note if the pre-processed MRs result contains the original MRs, then

uplink link interpolation is performed.

Selection of the MR Data

Two types of MRs are available: enhanced MR and normal MR.

The enhanced MR is a new downlink MR, reported by the MS. Compared with the normal MR,

some new measurements are added, such as BER, FER, and so on. The enhanced MR provides

the measurement information of up to 15 neighbor GSM/WCDMA cells, whereas the normal MR

provides the measurement information of 6 neighbor GSM cells at most.

In the MR, the TCH measurement of the serving cell is classified into FULLSET and SUBSET. The

FULLSET measures the TCH channels (signal receive level and quality), whereas the SUBSET

measures the channels in DTX mode (signal receive level and quality). The MRs provided by the

MS and BTS indicate whether the DTX scheme is adopted.

If DtxMeasUsed is set to TRUE, then the FULLSET or SUBSET values should be taken according

to the DTX indication bit in the MR. That is, if the MR indicates that DTX is used, then the SUBSET

values should be selected; otherwise, the FULLSET values should be selected.

If DtxMeasUsed is set to FALSE and the MR indicates that DTX is not used, the FULLSET values

should be taken; if the MR indicates that DTX is used, then the SUBSET values should be taken. In

the latter case, the SUBSET values should be used irrespective how DTX is indicated in the MR.

Interpolation Processing of the MRs

If the latest two received MR are not continuous, that is, their serial numbers are not consecutive,

then apply the interpolation as follows:

For the serving cell, when the number of lost MRs is less than the value ofAllowed MR Number Lost, then the linear interpolation of the MRs must beperformed.

For a neighbor cell, the worst interpolation value in accordance with protocolsshould be applied for the lost signal level measurement values; that is, level 0(-110 dBm) should be applied. For the neighbor cell with low signal level and theMR not provided, the worst interpolation value is also applicable.


If the number of lost MRs is greater than the value of Allowed MR Number Lost, then the previous

measurement values should be discarded and the recalculation should be performed on receipt of

the MRs.

The interpolation scheme applies to the following objects:

Uplink TCHs of the serving cell: RXLEV, RXQUAL, and RQIDownlink TCHs of the serving cell: RXLEV and RXQUALMRs of the serving cell that contain the information of TADownlink transmit power of the serving cell: Poff_DLReceive level of the downlink BCCHs of neighbor GSM cells: RXLEVDownlink CPICH, RSCP, and Ec/No of neighbor 3G cells

Filtering Processing of MRs

After the MRs requiring interpolation are interpolated, if the number of buffered valid MRs is smaller

than the filter length (the filters correspond to different measurement objects, signaling channel, or

traffic channel), then the filtering is not applied.

The averaging should be applied to the filtering processing. Parameters with different filter lengths

should be used during filtering on the basis of the measured values and type of the channel being

occupied. The parameter Filter length for TCH Level applied to the filtering of the downlink

transmit power of the serving cell.

The filtering scheme applies to the following objects:

Uplink TCHs of the serving cell: RXLEV, RXQUAL, and RQIDownlink TCHs of the serving cell: RXLEV and RXQUALMRs of the serving cell that contain the information of TA (optional)Downlink transmit power of the serving cellReceive level of the downlink BCCHs of neighbor GSM cells: RXLEVDownlink CPICH, RSCP, and Ec/No of neighbor 3G cells

1.3 Handover Decision Algorithms

After MRs are processed, the handover decision procedure starts. This procedure involves the

actions related to initial access, including handover protection, penalty, 16-bit queuing, forced

handover, handover decision making, processing of target 2G/3G cells, and initiation of continuous

handover.

Five types of handovers are available in terms of the triggering conditions: high-speed railway fast

handover, emergency handover, enhanced dual-band network handover, load handover, and

normal handover.

1.3.1 High-Speed Railway Fast Handover

This handover algorithm applies mainly to railway areas. The algorithm is designed in accordance


with the railway features, and thus can guarantee precision and reliable handover along the railway.

High-speed railway fast handover consists of frequency offset handover and fast PBGT handover.

1.3.2 Emergency Handover

To maintain the conversations in emergent situations (risk of calls being dropped), the handover

conditions could be less evaluated to enable the handover decision procedure being executed

quickly and the overall handover delay being shortened. As the handover conditions are evaluated

in less degree, the emergency handover algorithm produces greater error in evaluating the target

cell than that produced by other handover algorithms. In normal network operation, frequent

emergency handovers should be avoided.

Emergency handovers consist of TA handover, interference handover, quick level drop handover,

bad quality handover, no downlink measurement report handover.

1.3.3 Enhanced Dual-Band Handover

In a dual-band network, the resources in the overlaid 1800M subcell and underlaid 900M subcell

can be shared during the assignment and handover procedures. That is, the calls in the high-traffic

900M subcell can be moved to the low-traffic 1800M subcell to achieve traffic balance.

1.3.4 Load Handover

In the coverage area where several cells are neighbors to each other, the traffic might be distributed

unevenly, causing one cell or several cells being congested or blocked while the neighbor cells still

having available free channels for use. In such case, load handover is applied. Through load

handover, some calls, especially those on the edge of the high-traffic cells are moved to the

neighbor cells with low traffic volume.

The main disadvantage of load handover is that the target cells are not selected in close to the

serving cell, which is preferred in network planning. Therefore, inter-cell interference increases and

ping-pong reselection occurs. Even the ping-pong symptom can be mitigated with the introduction

of the penalty scheme, it is still unavoidable.

1.3.5 Normal Handover

Normal handover is generally used in maintaining continuous conversations. Normal handover

consists of the following types in terms of handover target and handover principles: edge handover,

fast movement handover for microcell, hierarchical handover, PGBT handover, concentric handover,

AMR handover, better 3G cell handover, and tight BCCH handover.


The 2G-to-3G handovers supported at present include TA handover, BQ handover, quick level drop

handover, interference handover, and edge handover. The handover algorithms determine whether

there are eligible neighbor 2G cells first; if there are eligible neighbor 2G cells, the following

decisions are taken according to the 2G cell list and 3G cell list:

If Inter-RAT HO Preference is set to Pre_2G_Cell and there are no eligibleneighbor 2G cells but with eligible neighbor 3G cells, then a 3G cell is preferred;otherwise, a 2G cell is selected.

If Inter-RAT HO Preference is set to Pre_3G_Cell, then a 3G cell is preferred. If Inter-RAT HO Preference is set to Pre_2G_CellThres and there are no

eligible neighbor 2G cells but with eligible neighbor 3G cells, then a 3G cell ispreferred; a 3G cell is also preferred if the receive level of the first candidate 2Gcell is lower than the value of HO Preference Threshold for 2G Cell.

Additionally, in the 3G better cell handover (2G-to-3G handover), if Better 3G Cell HO Allowed is

set to Yes, then a 3G cell is preferred.

The following figure shows procedure for the handover decision algorithms.


Procedure for the handover decision algorithms

Start

Interpolation and filteringprocessing of MRs

No downlink MRhandover decision-taking

Protection ofminimum handoverinterval triggered?

HOInterTimerprotection triggered forconsecutive handover

interval?

HOInitTimer protection triggered forminimum handover interval at initial

access phase

HOInitTimer:Min Interval for TCH HosMin Interval for SDCCH HosSDCCH HO Allowed

Penaltyprocessing

Basic queuing ofcandidate cells

Network characteristicstuning for candidate cells

Forced handover processing

Other handoverdecision-takings

HOInterTimer:Min Interval for Consecutive Hos

Determines targethandover cell basedon 2G/3GHOOPtSel

and 2GOrdThres

Starts consecutivehandover protectiontimer: HOInterTimer

End

High-speed railway fasthandover decision-taking

TA handover decision

Interference handoverdecision

Rapid level drophandover decision

Emergency handover

Min Interval forEmerg Hos triggered

Enhanced dual-bandhandover decision

Load handover decision

Edge handover decision

Hierarchicalhandover decision

PBGT handoverdecision

Concentrichandover decision

Normal handover

AMR handover decision

Better 3G cellhandover decision

Tight BCCHhandover decision

2G/3GHOOPtSe:FDD: Inter-RAT HO PreferenceTDD: TDD Inter-RAT HO Preference

2GOrdThres:FDD: HO Preference Threshold

for 2G CellTDD: TDD HO Preference

Threshold for 2G Cell

End

Yes

Yes

No

No

Fast-moving microcellhandover decision

Bad quality handoverdecision


1.3.6 No Downlink Measurement Report Handover

When the Um interface degrades, the MS might fail to send the downlink MRs due to bad uplink

quality, while it can still receive downlink signals because the downlink quality is acceptable. In such

emergent situations, the network initiates the handover and moves the MS to a neighbor cell to

avoid the call being dropped. The following figure shows the procedure for the handover decision:

No downlink measurement report handover procedure

No Dl Mr. HO Allowed isset to Yes?

At least one downlink MR is reported?

Number of consecutive lostMRs <= value of Cons. NoDl Mr. HO Allowed Limit?

Number of valid uplink MRs withquality value >= value of

Filter Length for SDCCH/TCH Qual?

No downlink MRs in theavailable MRs?

Uplink quality after filtering >= valueof No Dl Mr. Ul Qual HO Limit?

Only one eligible candidate cell is available?

The candidate cell is the servingcell?

Consecutive intracell handoverprohibited?

If the serving cell belongs to thecandidate cells, the serving cell

should be removed.

Start

No

Yes

Filter lengths for signal quality:

Filter Length for SDCCH Qual

Filter Length for TCH Level

No

No

No

No

No

Yes

Yes

Yes

Yes

Yes

Yes

No

No

Yes

Yes

Yes

Intracell HO Allowed is set to Yes ?

Forbidden Time after Max Times

EndNo downlink

measurement reporthandover is triggered.

No

No

The handover decision is triggered if the following conditions are met:

No Dl Mr. HO Allowed is set to Yes.The number of lost MRs is smaller than the value of Cons. No Dl Mr. HO Allowed

Limit.


There are no downlink measurement values available in the current MR.For TCH, the number of saved MRs with uplink receive quality value is greater than

the value of Filter Length for TCH Qual; for SDCCH, the number of saved MRswith uplink receive quality value is greater than the value of Filter Length forSDCCH Qual.

Filtered uplink receive quality value >= value of the No Dl Mr. Ul Qual HO Limit

1.3.7 Penalty Processing

To avoid the occurrence of ping-pong reselection from different handovers, the penalty mechanism

is introduced to the handovers such as TA handover, UL/DL BQ handover, fast-moving

micro-to-macro cell handover, and concentric cell handover.


Procedure for penalty processing

Penalty processingprocedure starts

Penalty applied to all2G candidate cells is

completed?

End

No

The TA penalty timerfor the neighbor cell

has not expired?No

Yes

Yes

Acutal signal level of theneighbor cell = measured signal

level of the neighbor cell -ucSSTAPunish

Penalty applied to all3G candidate cells is

completed?

This is the neighbor cell towhich the latest handoverfails. The handover failure

penalty timer has not expired?

No Yes

No

Yes

ucSSTAPunish:Penalty Level after TA HO

TA penalty duration:Penalty Time after TA HO(s)

ucSSBQPunish:Penalty Level after BQ HOBQ penalty duration:

Penalty Time after BQ HO

ucFailSigStrPunish:Penalty Level after HO FailHandover failure penalty duration:

Penalty Time after HO Fail

ucSpeedPunish:Penalty on MS Fast Moving HO

Speed penalty duration:Penalty Time on Fast Moving HO

ucQuickHoPunishValue:Quick Handover Punish Value

Frequency offset handoverpenalty duration:

Quick Handover Punish Time

ucFailSigStrPunish:Penalty Level after HO FailHandover failure penalty duration:Penalty Time after HO Fail (s)

After frequency offsethandover succeeds, the

penalty timer for the old cellhas not expired.

No

Yes

The BQ penalty timerfor the neighbor cell

has not expired?No

Yes

This is the neighbor cell to whichthe latest handover fails. Thehandover failure penalty timer

has not expired?No

Yes

After fast movement handoversucceeds, the speed penaltytimer for the old cell has not

expired.No

Yes

Acutal signal level of the neighborcell = measured signal level of the

neighbor cell - ucSSBQPunish

Acutal signal level of the neighborcell = measured signal level of theneighbor cell - ucFailSigStrPunish

Actual signal level of the neighborcell= measured signal level of theneighbor cell - ucSpeedPunish.

Actual signal level of theneighbor cell= measured

signal level of the neighborcell - ucFailSigStrPunish

Actual signal level of the neighborcell= measured signal level of the

neighbor cell -ucQuickHoPunishValue


1.3.8 Triggering Conditions of Penalty

Provided that the periodic MRs are received, the penalty should be introduced when the latest

handover succeeds or fails and the penalty procedure should start before the penalty timer expires.

The penalty scheme applies to the following situations:

An emergency handover caused by higher TA value succeeds;An emergency handover caused by bad uplink quality succeeds;An emergency handover caused by bad downlink quality succeeds;Penalty after handover fails, including the handovers to 2G cells and the handovers to

3G cellsPenalty on the microcell from which a fast-moving MS is handed over to the

macrocell;A high-speed railway fast handover succeeds;An overlaid-to-underlaid handover succeeds;An overlaid-to-underlaid handover or underlaid-to-overlaid handover fails;

1.3.9 Penalty Processing

After the latest emergency handover is triggered due to higher TA value, the TApenalty timer is started, the duration being Penalty Time after TA HO(s). If theemergency handover succeeds, then the MS in the target cell (serving cell) shallqueue, within the penalty duration, the neighbor cells among which the actualreceive level of the old cell should be subtracted with the value of Penalty Levelafter TA HO. This enables the queuing priority of the old cell to be decreased. Ifthe emergency handover fails, then the MS in the current serving cell shall queue,within the penalty duration, the neighbor cells among which the actual receivelevel of the target cell should be subtracted with the value of Penalty Level afterTA HO. This enables the queuing priority of the target cell to be decreased andthus avoids unnecessary handover and handover failures.

After the latest UL/DL bad quality emergency handover (after an interferencehandover is triggered, the cause value is bad quality handover) or outgoing MSCforced handover is triggered, the bad quality penalty timer is started, the durationbeing Penalty Time after BQ HO (s). The MS in the target cell (serving cell) shallqueue, within the penalty duration, the neighbor cells among which the actualreceive level of the old cell should be subtracted with the value of Penalty Levelafter BQ HO. This enables the queuing priority of the old cell to be decreasedand thus avoids ping-pong handovers.

After the latest handover to a neighbor 2G or 3G cell fails, the 2G/3G handoverpenalty timer is started, the duration being Penalty Time after HO Fail(s). TheMS in the serving cell shall queue, within the penalty duration, the neighbor cellsamong which the actual receive level of the target cell should be subtracted withthe value of Penalty Level after HO Fail. This enables the queuing priority of thetarget cell to be decreased and avoids further handover failures.

If the serving cell belongs to the highest layer (layer 4) defined by Cell Layer, and thecause for the previous handover is fast-moving, then the speed penalty timer forthe neighbor cells is started, the duration being Penalty Time on Fast MovingHO. The MS in the serving cell shall queue, within the penalty duration, thenon-layer 4 neighbor cells whose actual receive level should be subtracted with


the value of Penalty on MS Fast Moving HO. This enables the queuing priorityof the target cell to be decreased and avoids handovers to microcells (non-layer 4neighbor cells).

If the latest handover is a high-speed railway fast handover, then the penalty timer isstarted, the duration being Quick Handover Punish Time. The MS in the targetcell (serving cell) shall queue, within the penalty duration, the neighbor cellsamong which the actual receive level of the old cell should be subtracted with theQuick Handover Punish Value. This enables the queuing priority of the old cell tobe decreased and avoids ping-pong handover.

If the latest overlaid-to-underlaid handover is triggered, then the penalty timer isstarted, the duration being Penalty Time of UtoO HO(s). Within the penaltyduration, the MS is not allowed to be handed over to the overlaid subcell. For theenhanced dual-band network, if the overlaid-to-underlaid handover is trigged withnormal handover cause or OtoU handover cause, then the penalty timer isstarted, the duration being Inn Out Cell HO Penalty Time. Within the penaltyduration, the underlaid-to-overlaid handover is not allowed.

If the latest overlaid-to-underlaid or underlaid-to-overlaid handover fails, then thehandover failure penalty timer is started, the duration being Penalty Time afterOtoU HO Fails(s)/Penalty Time after UtoO HO Fails(s). Within the penaltyduration, the overlaid-to-underlaid or underlaid-to-overlaid handover is notallowed.

1.3.10 Basic Queuing

The purpose of basic queuing is to produce the candidate cell list with the following information

taken into account: neighbor cell information after penalty processing, parameters contained in the

MRs, such as the signal level of the serving cell and neighbor cells, hysteresis, usage of TCHs in

the neighbor cells, and so on.

The basic queuing module functions in accordance with the M criterion and K criterion.


Processing procedure for the M criterion

Processing of Mcriterion starts.

Inter-BSC SDCCH HOAllowed is set to Yes?

Remove this cell fromthe candidate cell list.

Yes

Yes

Yes

No

No

This is a BSC external cell.The occupied channel is a

SDCCH?

No

Yes

Direct retry?

No

No

Whether the cell isoverloaded? If so, removethe cell from the candidate

cell list.

Downlink signal level of the candidate cell< HOCdCellMinDwPwr + MCriteriaOffset?

Remove the cellfrom the candidate

cell list.

Uplink signal level of the candidate cell <HOCdCellMinUpPwr + MCriteriaOffset)

No

M criterion decision-taking of 3G cells:

FDD 3G cell or TDD 3G cell?

UtranCellType=FDD

UtranCellType= TDD

TDD neighbor cellsupports only RSCP.

Take FDD MRvalues.

0 (RSCP) 1 (Ec/No)

Penalizedmeasurement value< MinRSCPThres

Penalizedmeasurement value

< MinEcNoThres

Yes Yes

Remove the 3Gcell from the

candidate cell list.

No

Decision-taking of all 2Gcandidate cells is completed?

No

End

NoNo

Inter-BSC SDCCH HOAllowed:

This parameter specifieswhether inter-BSC SDCCH is

allowed.

HOCdCellMinDwPwr:Min DL Level on Candidate Cell

HOCdCellMinUpPwr:Min UL Level on Candidate Cell

MCriteriaOffset:Min Access Level Offset

UTRAN Cell Type:This parameter specifieswhether the 3G cell is ofFDD or of TDD. 0 means

FDD and 1 TDD.

FDD REP QUAN :This parameter specifieswhich scheme does the

MR use: Ec/No or RSCP.

MinRSCPThres:Min RSCP Threshold

MinEcNoThres:Min Ec/No Threshold

Yes

Yes

Yes

Yes

M criterion decision-taking ofall 3G candidate cells is

completed?


M criterion: The neighbor cells that do not meet conditions such as receive levelthreshold and cell load level are removed from the candidate cell list.− In non-direct retry situation, if an MS in a BSC external cell occupies an

SDCCH and the Inter-BSC SDCCH HO Allowed is set to No, then the cellshould be removed from the candidate cell list; that is, the handover to theBSC external cell is prohibited.

− If the cell is overflowed, then the cell should be removed from the candidatecell list, and thus the handover to the cell is prohibited.

− If the downlink receive level (RXLEV, after filtering and penalty) of a 2G cell islower than the sum of Min DL Level on Candidate Cell and Min AccessLevel Offset, then the 2G cell should be removed from the candidate cell list;that is, the handover to this neighbor cell is prohibited. The parameters MinDL Level on Candidate Cell and Min Access Level Offset apply only toneighbor cell configuration. For the serving cell, Min Access Level Offset ispermanently set to 0.

− If the uplink receive level (RXLEV, after filtering and penalty) of a 2G cell islower than the sum of Min UL Level on Candidate Cell and Min AccessLevel Offset, then the 2G cell should be removed from the candidate cell list;that is, the handover to this cell is prohibited. The parameters Min UL Levelon Candidate Cell and Min Access Level Offset apply only to neighbor cellconfiguration. For the serving cell, Min Access Level Offset is permanentlyset to 0.

− For 3G cells, distinguish between FDD cells and TDD cells first. For an FDDcell, indicate whether the Ec/No or RSCP is used for the MR according to FDDREP QUANT; if the RSCP value is used, then the cell should be removed fromthe candidate cell list when the penalized RSCP value is lower than the valueof Min RSCP Threshold; if the Ec/No value is used, then the cell should beremoved from the candidate cell list when the penalized Ec/No value is lowerthan the value of Min Ec/No Threshold. For a TDD cell, only the RSCP valuecan be reported. In this case, the cell should be removed from the candidatecell list when the penalized RSCP value is lower than the value of Min RSCPThreshold.

K criterion: The K values of each cell are computed. Then, the cells are queued indescending order according to their K values. A greater K value means that thesignal level in the cell is better.


Processing procedure for the K criterion

Queue the 3G cells based onthe measurement values and

update the priority levels of theneighbor cells

Processing of Kcriterion starts.

The K values of all2G candidate cells

are computed?

End

No

3G cell typejudgement

This is the servingcell?

The K value of theserving cell is 0.

Yes

No

UtranCellType= FDDUtranCellType= TDD

Take FDD MRvalues.

0 (RSCP) 1 (Ec/No)TDD neighbor cellsupports only RSCP.

Yes

UTRAN Cell Type:This parameter specifieswhether the 3G cell is ofFDD or of TDD. 0 means

FDD and 1 TDD.

FDD REP QUAN:This parameter specifies

which scheme does the MRuse: Ec/No or RSCP.

RSCPOff: RSCP OffsetEcNoOff: Ec/No Offset

No

Yes

K value of the neighbor cell =BCCH signal level of the neighbor cell

after filtering - compensated signallevel of the serving cell - KIAS

Performs popup queuing of the2G candidate cells based on Kvalues and updates the prioritylevels of the candidate cells.

The K values of all 3Gcandidate cells are

computed?

Measurement value of theneighbor cell =

measured value of theneighbor cell - RSCPOff

Measurement value of theneighbor cell = measuredvalue of the neighbor cell -

EcNoOff

KIAS:1. For a BSC internal neighbor cell,KIAS = K Bias2. For a BSC external neighbor cell,KIAS = 0

The K value of the serving cell is 0. For a neighbor 2G cell, K = BCCH signal level of the neighbor cell after filtering –

TCH signal level of the neighbor cell after filtering –KIAS; For a neighbor 3G cell, distinguish between Ec/No and RSCP in the MR first; if

the RSCP value is used, then actual measurement value in the neighbor cell =


original measurement value in the neighbor cell –RSCP Offset; if the Ec/Novalue is used, then actual measurement value in the neighbor cell = originalmeasurement value in the neighbor cell – Ec/No Offset. Update the prioritylevels of the neighbor 3G cells based on the measurement values.

1.3.11 Network Characteristics Adjustment

The network characteristics adjustment refers to the 16-bit queuing for the candidate cells. Error!

Reference source not found. describes the format of 16-bit queuing.


After the basic cell queuing, priority adjustment is performed on the candidate cells to define the

comprehensive priority of each candidate cell. The priority adjustment is based on the receive

signals, receive quality, cell load, inter-layer handover threshold, layer-level difference,

co-BSC/co-MSC/co-MNC or not for the serving cell and the neighbor cell, and the timeslot extension

type. After the priority adjustment, the cell queuing is performed again.

In the 16-bit queuing, bit 1 (LSB) has the lowest weight and bit 16 (MSB) has the highest weight.The

value of the 16 bits indicates the cell priority. A low value of the 16 bits indicates a high cell priority.

A cell with a high cell priority has great chance of being the target cell for a handover.


Network characteristic adjustment procedure

Start networkcharacteristics

adjustment

Network characteristics adjustment for all theneighbor 2G cells complete?

End

NO

YES

Load bit adjustment

System load < SYSFLOWLEV ANDLoad HO Allowed is YES?

SYSFLOWLEV: System FluxThreshold for Load HOucLoadHoEn: Load HO AllowedNO

YES

Serving cell or not?YES

Load of serving cell > =TrigThres

TrigThres: Load HO ThresholdAccThres: Load Req. onCandidate Cell

YES

Load bit of servingcell set to 1

NO

Load bit of servingcell set to 0

NO

Load of neighbor cell > =AccThres

YES NO

Load bit of neighborcell set to 1

Load bit of neighborcell set to 0

Co-BSC or not?YES NO

Co-MSC or not?YES NO

Different BSC: BIT 12set to 1

Different MSC: BIT 13set to 1

Serving cell or not?YES NO

DL RXLEV of the serving cell < ucLevThr -ucLevHyst

YES NO

Serving cell: BIT 14set to 1

BIT 5-13 set to 0

DL RXLEV of the neighbor cell <ucLevThr + ucLevHyst

YES NO

Neighbor cell: BIT 14set to 1

BIT 5-13 set to 0

Serving cell or not?YES NO

Serving cell: BIT 4 setto 0 permanently

RX level of neighbor cell < RX level of servingcell + ucInterCellHyst

YES NO

Neighbor cell: BIT4 set to 1

Neighbor cell: BIT4 set to 0

Cell queuing based on the 16-bitvalue. A high 16-bit value indicates a

low cell priority.

Priority queuing forneighbor 3G cells

ucInterLevHoThres: Inter-layer HOThresholducLevHoHyst: Inter-layer HOHysteresis

ucInterCellHyst: Inter-cell HOHysteresis

ucCoBscMscAdjEn: Co-BSC/MSCAdj

Co-BSC/MSC adjustment allowed?YES NO


Bits 1-3: Indicates the priority of the DL receive level (on the TCH or BCCH) of a cell.The priority is based on the queue arranged by K in the basic queuing. A highvalue of K indicates a small value of bits 1-3, which means a high priority.

Bit 4: Set to 0 permanently for the serving cell. Set to 0 for the neighbor cell if thefollowing formula is applied. Otherwise, Bit 4 is set to 1 for the neighbor cell.

_ __i f i s fSS H SS DL

In this formula,

SSi_f indicates the BCCH receive level in the neighbor cell i after filtering.

Hi indicates Inter-cell HO Hysteresis, the hysteresis configured for the neighbor cell i.

SS_DLs_f indicates the receive level of the downlink TCH in the serving cell after filtering.

Bits 5-10: Indicates the layer attribute and level attribute of a cell. Bits 9-10 indicatelayer attribute and bits 5-8 indicate level attribute. The mapping formula is asfollows:

16layer_level layer levelP P P

In this formula,

Player_level indicates the comprehensive priority on the layer and level basis afterthe mapping. The corresponding bits are bits 5-10 with the value range 0 to 63.

Player indicates the layer attribute of the neighbor cell or serving cell with the valuerange 0 to 3.

Plevel indicates the level attribute of the neighbor cell or serving cell with the valuerange 0 to 15.

Bit 11: Indicates the cell load weighting. If the system load is higher than System FluxThreshold for Load HO, or if Load HO Allowed is disabled, then bit 11 is set tothe default value.

The formula is different for the serving cell and neighbor cell.

Serving cell: Set to 0 if the following formula is applied. Otherwise, Bit 11 is set to1.

_s s lL T

In this formula,

Ls indicates the current load of the serving cell.

Ts_l indicates Load HO Threshold of the service cell.

Neighbor cell: Set to 0 if the following formula is applied. Otherwise, Bit 11 is setto 1.

_i i lL T


In this formula,

Li indicates the current load of the neighbor cell i.

Ti_l indicates Load Req. on Candidate Cell of the neighbor cell.

5. Bit 12: If Co-BSC/MSC Adj is set to YES, bit 12 indicates the high priority of theneighbor cells that share the BSC with the serving cell. Bit 12 is set to 0 for theneighbor cells that share the BSC with the serving cell.

Bit 13: If Co-BSC/MSC Adj is set to YES, bit 13 indicates the high priority of theneighbor cells that share the MSC with the serving cell. Bit 13 is set to 0 for theneighbor cells that share the MSC with the serving cell.

Bit 14: Indicates whether a candidate cell is better than the serving cell. If thecandidate cell is better, load and hierarchy should be taken into account. Theformula is different for the serving cell and neighbor cell.

Serving cell: Set to 0 if the following formula is applied. Otherwise, set to 1.

__ s f layer layerSS DL T H (0.1)

In this formula,

− SS_DLs_f indicates the DL receive level on the TCH of the serving cell afterfiltering.

− Tlayer indicates Inter-layer HO Threshold.

− Hlayer indicates Inter-layer HO Hysteresis. Neighbor cell: Set to 0 if the following formula is applied. Otherwise, set to 1.

_f layer layeriSS T H ＋ (0.2)

In this formula,

− SSi_f indicates the receive level on the BCCH of the neighbor cell after filtering.− Tlayer indicates Inter-layer HO Threshold of the neighbor cell.− Hlayer indicates Inter-layer HO Hysteresis of the neighbor cell.

If bit 14 is set to 1 (for either serving cell or neighbor cell), then bits 5-13 are set to0. That is, the factors such as hierarchy, load, and co-BSC/co-MSC are not takeninto account if bit 14 is set to 1. In this case, only the DL receive level andhysteresis are taken into account.

Bits 15-16: reserved

1.3.12 Forced Handover

If the forced handover is triggered, the subsequent handover decision is not performed. Purpose of

the forced handover: If no TCH is available in the serving cell during the MS access process, the

direct retry procedure is performed when Direct Retry is set to YES. When BTS maintenance is

performed, the users under control of the related BTS should be handed over to the cells controlled

by a functional BTS to ensure that no call drops occur during BTS maintenance. According to the

background forced handover type, the ineligible cells in the candidate cell list are removed. The


forced handover is categorized into four types, namely, inter-cell handover (direct retry), inter-site

handover, inter-BSC handover, and specified cell list handover.

1.3.13 Handover Decision

The handover decision is categorized into five types, namely, high-speed railway fast handover,

emergency handover, enhanced dual-band handover, load handover, and normal handover. The

emergency handover is of five types, which are TA handover, bad quality (UL/DL) handover, quick

level drop handover, interference handover, and no downlink measurement report handover. The

normal handover is of the following types: edge handover, hierarchical handover, PBGT handover,

concentric cell handover, AMR handover, and better 3G cell handover.

Each handover algorithm consists of two parts. One is to decide whether the serving cell meets the

triggering conditions, and the other is to select the candidate cells.-{}-

A list of 2G or 3G candidate cells is generated based on the parameter Inter-RAT HO Preference.

The parameter is set to Pre_2G_Cell: A 2G cell in the 2G candidate cell list ispreferred as the target cell.

The parameter is set to Pre_3G_Cell: A 3G cell in the 3G candidate cell list ispreferred as the target cell.

The parameter is set to Pre_2G_CellThres: If the receive level of the firstcandidate cell in the 2G candidate cell list is equal to or smaller than HOPreference Threshold for 2G Cell, a 3G cell is preferred as the target cell.Otherwise, a 2G cell is preferred as the target cell.

1.3.14 Emergency Handover

When any of the following emergency handover decision meets the emergency handover conditions

(number of candidate cells not zero), the emergency handover timer is started. The duration of the

timer is defined by Min Interval for Emerg Hos. Another emergency handover can be decided only

when the timer expires.

1.3.15 TA Handover

When TA HO Allowed is set to Yes and the neighbor cells are not in emergency handover penalty

state, based on the MR and serving cell attributes after the basic queuing, the TA handover decision

is made according to the following rule:

The filtered TA value of the serving cell >= value of TA Threshold.

If the TA decision is allowed, the candidate cell selection is performed. The serving cell is removed. If the handover is triggered because the TA is too high, the co-site neighbor cells

that meet the following conditions are removed:


TA Threshold of the neighbor cell <= TA Threshold of the serving cell

If the TA handover decision is allowed but the number of 2G candidate cells iszero, then:

If a 3G neighbor cell is available and if the system parameter (Outgoing-RAT HOAllowed) and the MS capability support the 2G->3G handover, the 2G->3Ghandover is performed directly.

If no eligible neighbor 3G cell available or if the 2G -> 3G handover is not allowedbecause of the system parameter configuration and the MS capability, then thesubsequent decision on another emergency handover type is performed.

If the TA handover decision is not allowed, then the subsequent decision onanother emergency handover type is performed.

The following figure shows the procedure for the TA handover decision.


Procedure for the TA handover decision

s_TA: filtered TA of the serving cellTAlimit: TA Threshold

SYS_HO: Outgoing-RAT HOAllowed

Start

Whether a 2G/3G candidate cellexists?

NO

YES

TA_HO YES or NO?NO

s_TA>=TAlimit?

YES

End

NO

YES

Whether a 2G candidate cellexists?

NO

Eligible 2G target cellexists?

YES NO

SYS_HO is YES, a neighbor 3Gcell exists, and MS supports inter-

RAT handover?

End

NO

YES

YES

TA_HO: TA HO Allowed

TA handoverinitiation

Inter-RAThandover


YES

NO

NO

Candidate cellqueue traverse

A co-site neighbor cell of which TAThreshold <= TA Threshold of the serving

cell?

1.3.16 Interference Handover

If the TA handover conditions are not met, Interference HO Allowed is set to YES, and if the

neighbor cells are not in emergency handover penalty state, the uplink/downlink interference

handover decision is made according to the following rules:

Filtered uplink/downlink receive quality measurement in the serving cell >= AThe A of the AMR call and non-AMR call corresponds to different parameters:


AMR call: A is RXQUAL1 (n=1); RXQUALn + RXLEVOff (2≤n≤12)

Non-AMR call: A is RXQUALn (1≤n≤12)

If the uplink/downlink interference handover decision is allowed and if the numberof 2G candidate cells is not zero, then the candidate cell selection is performed.

If Intracell HO Allowed is set to YES and if the intra-cell handover penalty timerexpires (when a certain number of consecutive intra-cell handovers occur, thetimer Forbidden Time after Max Times (s) starts to forbid the intra-cellhandover), then the serving cell can be the target cell. Otherwise, the serving cellis removed.

The candidate neighbor cell (not the serving cell) must meet the followingconditions:

Receive level on the BCCH of the neighbor cell after filtering and penalty >= Inter-layer HO

Threshold + Inter-layer HO Hysteresis of the neighbor cell

The following figure shows the procedure for the interference handover decision.


Procedure for the interference handover decision


Start


NO

YES

Interfere_HO is YES?NO

sULQual or sDLQual >= A?

YES

End

NOsULQual or sDLQual: UL or DL RX quality of theserving cellA:1. For a non-AMR call, A is RXQUAL1-12.2. For an AMR call, A is RXQUAL1-12 +RXLEVOff.


NO


YES NO

SYS_HO is YES, a neighbor 3G cellexists, and MS supports inter-RAT

handover?

YES

YES

End

NO

Interfere_HO: Interference HOAllowed

YES

Intra_HO: Intracell HO Allowed

Inter-RAThandover

ucLev: RXLEV on the BCCH of theneighbor cell

ucLevThr: Inter-layer HO Threshold ofthe neighbor cell

ucLevHyst: Inter-layer HO Hysteresis ofthe neighbor cell

Interferencehandover initiation

Serving cell or not?

Intra_HO is YES and thecell is not in penalty state?

NO

YES

ucLev>=ucLevThr+ucLevHyst?

NO

YES YES

Candidate cellqueue traverse

NO

1.3.17 Quick Level Drop Handover

If the TA/interference handover conditions are not met, Rx_Level_Drop HO Allowed is set to YES,

and if the neighbor cells are not in emergency handover penalty state, the quick level drop handover


decision is made according to the following rules. The level values in this decision are not filtered.

If the MR used for handover decision is a pre-processed MR, then the flag bit inthe MR is used for handover decision directly.

If the MR is not pre-processed, then

SS_ULs_fm_f<-B AND __ s_interp_1 border ulSS UL T

In this formula,

SS_ULs_interp_1 indicates the receive level on the latest uplink TCH of the serving cell.

Tborder_ul indicates Edge HO UL RX_LEV Threshold.

B indicates Filter Parameter B.

SS_ULs_fm_f is equal to original uplink receive level x Filter Parameter A1-A8.

If the quick level drop handover decision is allowed and if the number of 2Gcandidate cells is not zero, then the candidate cell selection is performed.

The 2G neighbor cell of which the 16-bit value is smaller than that of the servingcell.

If the quick level drop handover decision is allowed but the number of 2Gcandidate cells is zero:

If there is an available 3G neighbor cell, and if the system parameter(Outgoing-RAT HO Allowed) and the MS capability support the 2G -> 3Ghandover, then the 2G -> 3G handover is performed directly.


If the quick level drop handover decision is not allowed, then the subsequentdecision on another emergency handover type is performed.

The following figure shows the procedure for the quick level drop handover decision.


Procedure for the quick level drop handover

Start


NO

YES

QuickFall_HO is YES?NO

SS_ULs_fm_f<-B ANDSS_ULs_interp_1<Tborder_ul?

YES

End

NO


YES

Priority of the 2G candidate cellhigher than the serving cell?

YES NO


handover?

NO

YES

End

NO

YES

Inter-RAThandover

Quick level drophandover initiation

Candidate cell queuetraverse


NO YES

MR<AvailNum ORAvailNum=0?

YESNO

MR: number of measurementreports obtainedAvailNum: number of availablefilter parameters in FilterParameter A1–A8

SS_ULs_fm_f: Original uplink receivelevel x Filter Parameter A1-A8B: Filter Parameter BSS_ULs_interp_1: the receive levelon the latest uplink TCH of theserving cell.Tborder_ul: Edge HO UL RX_LEVThreshold

QuickFall_HO: Rx_Level_DropHO Allowed


1.3.18 Bad Quality Handover

If the TA/interference/quick level drop handover conditions are not met, BQ HO Allowed is set to

YES, and if the neighbor cells are not in emergency handover penalty state, the bad quality (BQ)

handover decision is made according to the following rules:

Filtered uplink receive quality of the serving cell >= UL Qual. Threshold ORFiltered downlink receive quality of the serving cell >= DL Qual. Threshold

For an AMR call, the parameters ULQuaLimitAMRFR/DLQuaLimitAMRFR and

ULQuaLimitAMRHR/DLQuaLimitAMRHR are used for handover decision.


If the BQ handover decision is allowed, the candidate cell selection is performed. If the candidate cells include the neighbor cells except the serving cell, and if the

neighbor cells meet the following formula:Filtered RXLEV_DL of the neighbor cell after penalty > Filtered RXLEV_DL of the serving cell +

Inter-cell Handover Hysteresis of the serving cell configured for the neighbor cell –BQ HO Margin,

then the outgoing cell handover procedure is preferred.

If the number of candidate cells is 1, then the above condition for the neighbor cell isunnecessary. If the neighbor cells do not meet the above condition or if the candidate cell list

includes only the available serving cell, and if Intracell HO Allowed is set toYES and the serving cell is not in intra-cell handover penalty state, then thecandidate cell list keeps only the serving cell. The assignment strategy is differentfrequency bands, different frequencies set, different TRXs, and different timeslots(assignment priority: different frequency bands > different frequencies set >different TRXs > different timeslots).

If the BQ decision is allowed but the number of candidate cells is zero: If there is an available 3G neighbor cell, and if the system parameter

(Outgoing-RAT HO Allowed) and the MS capability support the 2G -> 3Ghandover, then the 2G -> 3G handover is performed directly.


If the BQ handover decision is not allowed, then the subsequent decision onanother emergency handover type is performed.

The following figure shows the procedure for the BQ handover decision.


Procedure for the BQ handover decision

Start


NO

YES

BQ_HO is YES?NO

sULQual>=ULQuaLimit ORsDLQual>DLQuaLimit?

YES

End

NO

sULQual/sDLQual: UL/DL RX quality of theserving cellULQuaLimit/DLQuaLimit:1.UL/DL Qual. Threshold for a non-AMRcall2.ULQuaLimitAMRFR/DLQuaLimitAMRFR for an AMR FR call3.ULQuaLimitAMRHR/DLQuaLimitAMRHR for an AMR HR call


NO


YES NO


handover?

YES

YES

End

NO

BQ_HO: BQ HO Allowed

YES

Inter-RAThandover


ucLev: filtered DL RXLEV of the neighborcellsLev: DL RXLEV of the serving cell (afterpower control)InterCellHyst: Inter-cell HandoverHysteresisBQMargin: BQ HO Margin



ucLev-sLev>InterCellHyst-

BQMargin?

Intra_HO is YES and thecandidate cell is not in

penalty state?

YESNO

NONO

YESYES

Intra_HO: Intracell HO Allowed

BQ emergencyhandover to theneighbor cell is

initiated preferentially.

1.3.19 Load Handover

The load handover is only for the 2G handover and cannot be used for 2G -> 3G

handover.The load handover decision is not performed even if the system load is

higher than System Flux Threshold for Load HO.

When the emergency handover and enhanced dual-band network handover are not

triggered and when Load Handover Allowed is set to YES, the load handover

decision is made according to the following rules:

The load handover is allowed only when the CPU usage of thecurrent system is smaller than or equal to System Flux Thresholdfor Load HO.

Current load of the serving cell >= value of Load HO Threshold If the load handover decision is allowed, the hierarchical load

handover is performed. The calculation formula of the loadhandover strip is as follows:

1T

A StepPeriod

In this formula,

A is the width of the handover strip.

T is the timer of the load handover.

Period is Load HO Step Period (s).

Step is Load HO Step Level.

A cannot exceed the value of Load HO Bandwidth.

Power control compensation. The filtered downlink RXLEV on theTCH of the serving cell is compensated.

s_f_comp s_f s_f_ _ 2SS DL SS DL Poff_DL ＋

In this formula,

SS_DLs_f_comp is the compensated RXLEV on the downlink TCH.

SS_DLs_f is the filtered RXLEV on the downlink TCH.

Poff_DLs_f is the power offset of the BTS transmit power compared with the

maximum transmit power on the downlink TCH after filtering. The offset level is 2 dB.

The system assigns the MS to different load handover strips basedon the downlink RX level so that the call is handed over out of thecell step by step.


Page 38

s_f_compClsHoStart _ ClsHoStart +ASS DL

In this formula,

ClsHoStart indicates Edge HO DL RX_LEV Threshold, which is the start of the

handover strip.

A is the handover strip using the above formula.

If the load handover strip decision formula is applied, the candidatecell selection is performed.− The serving cell and external cell are removed.− The candidate cell must meet the following formula:

_f layer layeriSS T H ＋

In this formula,

SSi_f indicates the receive level on the downlink BCCH after filtering and penalty in

the neighbor cell.

Tlayer indicates Inter-layer HO Threshold.

Hlayer indicates Inter-layer HO Hysteresis.

The load of a candidate cell must meet the following formula:

iTloadLi _

In this formula,

Li indicates the current load of the neighbor cell i.

Tload_i indicates Load Req. on Candidate Cell of the neighbor cell i.

If the load handover decision is not allowed, then the subsequentdecision on another handover type is performed.

The following figure shows the procedure for the load handover decision.


Page 39

Procedure for the load handover decision

Start

Whether a neighbor 2Gcell exists?

NO

Load_HO is YES?

System flow≤SysFlowLev？

NO Load_HO: Load HandoverAllowed

SysFlowLev: System FluxThreshold for Load HO

NO

Load of serving cell≥LoadTrigThres？

LoadTrigThres: Load HOThreshold

NO

Timer of load handoverstarted?

A＝(T/Period+1)*Step

A: width of the load handover stripT: timer of the load handoverPeriod: Load HO Step PeriodStep: Load HO Step LevelOffset: Load HO Bandwidth

Start thetimer

ClsHoStart<SS_DLs_f_comp<ClsHoStart+A

NO ClsHoStart: Edge HO DL RX_LEVThresholdSS_DLs_f_comp: RXLEV of theserving cell after power controlcompensation


Remove the co-groupcell of the enhanced

dual-band network cell


NO

YES

YES

NO

YES

YES

YES

YES

SSi_f >= Tlayer+Hlayer ANDload of neighbor cell < Tload_i?

SSi_f: BCCH RXLEV of the neighbor cellafter filteringTlayer: Inter-layer HO Threshold of theneighbor cellHlayer: Inter-layer HO Hysteresis of theneighbor cellTload_i: Load Req. on Candidate Cell

Internal neighbor cellof the BSC?


YES

Load handoverinitiation

NO SSi_f >=Tlayer+ Hlayer?

YES NO

YES YES

NO

NO

End

Timer expires?

NO YES

A＝Offset

1.3.20 Normal Handover


Page 40

1.3.21 Edge Handover

If Fringe HO Allowed is set to Yes, the edge handover is allowed. If none of the

high-speed railway fast handover, emergency handover, enhanced dual-band

network handover, and load handover is triggered, the edge handover may be

triggered when all the following conditions are met:

Measured value of signal strength on the uplink TCH after filtering < value of Edge

HO UL RX_LEV Threshold; Measured value of signal strength on the downlink TCH

after filtering < value of Edge HO DL RX_LEV Threshold

According to the P/N criterion, if N reports out of the latest P MRsmeet the previous formulas, the uplink/downlink edge handover istriggered and the candidate cells are selected.− Remove the serving cell from the candidate cell list− Remove the neighbor cell whose 16-bit sequence number is

greater than the 16-bit sequence number of the serving cell. Ifthe sequence number is small, the priority of the cell is high.

− The neighbor cells should meet the P/N (Edge HO Valid Time(s)/Edge HO Watch Time (s) criterion.

If the edge handover decision is allowed but the number ofcandidate 2G cells is zero, then:

− If a neighbor 3G cell is available, the 2G -> 3G handover isperformed directly when the system parameter Outgoing-RATHO Allowed is set to Yes and the MS supports the 2G -> 3Ghandover.

− If no neighbor 3G cell is available, or if the system parameterconfiguration and the MS do not support the 2G -> 3G handover,then the subsequent handover decision is performed.

The following figure shows the procedure for the edge handover decision.


Page 41

Procedure for the edge handover decision

Is Fringe HO Allowed set toYes?

For neighbor cell whose 16-bitpriority level is higher than serving cell,

update edge handover counter

Update UL levelbad counter

UL receive level < Edge HO ULRX_LEV Threshold?

Yes

Yes

End No

Bad UL level meets P/Ncriterion?

Update DL levelbad counter

DL receive level < Edge HO DLRX_LEV Threshold?

Yes

Bad DL level meets P/Ncriterion?

No

No

No

Do candidate 2Gneighbor cells exist?

Yes

No

End No

Trigger edgehandover

Fast-moving micro cellhandover decision

Whether to trigger fast-movingmicro-macro cell handover?

Yes

Trigger fast-movingmicro-macro cell

handoverYes

Filter candidate neighbor cells(edge handover counter forcandidate cells meets P/N

criterion

No

Trigger outgoingRAT handover

Start (MR input)

N: Edge HO Watch Time(s)P: Edge HO Valid Time (s)



Do candidate 3G neighbor cells existand is Outgoing-RAT HO Allowed

set to Yes?Yes

End

No

Do candidatecells exist?

Yes

No

Yes


Page 42

1.3.22 Fast-Moving Micro-to-Macro Cell Handover

If MS Fast Moving HO Allowed is set to Yes, the fast-moving micro-to-macro cellhandover is allowed. The fast-moving micro-to-macro cell handover is mainlyapplicable to the high-speed environment, such as highways. In the handover, twolayers of network coverage are involved: micro cell and macro cell.

If none of the high-speed railway fast handover, emergency handover, enhanced

dual-band network handover, load handover, and edge handover is triggered, the

fast-moving micro-to-macro cell handover decision is performed when the triggering

conditions of edge handover or PBGT handover are met. The decision conditions are

as follows:

If the duration for an MS to stay in the serving cell is less than the valueof MS Fast-moving Time Threshold (s) (the time threshold iscalculated based on the cell radius (r) and the velocity (v), that is, 2r/v),the number of fast-moving cells for the MS is calculated once. The MS travels across a number of cells (the number is specified

by MS Fast-moving Watch Cells) in sequence. Among thesecells, a small number of cells (the number is specified by MSFast-moving Valid Cells) are of fast movement.

If the decision conditions are met and if the number of candidate2G cells is not zero, then the candidate cells are selected.

− Penalty processing should be applied to neighbor cellsbetween the M sorting and the K sorting (see the sectioninvolving basic sorting).

− The target cell is a macro cell. In other words, the level ofthe cell is 4.

− The candidate neighbor cells (not the serving cell) mustmeet the following:

Receive level of the BCCH in neighbor cells after filtering and penalty ≥ value of

Inter-layer HO Threshold + value of Inter-layer HO Hysteresis

The neighbor cells have the smallest 16-bit sequence number.

The following figure shows the procedure for the fast-moving micro-to-macro cell

handover decision.


Page 43

Procedure for the fast-moving micro-to-macro cell handover decision

Is MS Fast MovingHO Allowed set to

Yes?

End

Start(MR input)

Is optimum neighborcell the serving cell?

Yes

Update fastmovement counter

Is neither optimum neighborcell nor serving cell the level-

4 cell?

Is optimum neighbor cellthe source cell of theprevious handover?

Is fast movement timertimed out?

Meet P/N criterion for fastmovement ?

Yes

No

No

No

No

No

Yes

Trigger fastmovementhandover

Yes

Yes

Yes

Choose a level-4 cellthat meets Inter-layer HO

Level Threshold

Does an elegiblelevel-4 cell exist?

Yes

No

No

The fast movement timer is used tomonitor the number of edge

handovers and PBGT handoverswithin TI_QUICKPASS after MSenters the cell. If the number of

handovers meets the P/N criterion,the MS is in fast-moving state.

P: MS Fast-moving Valid CellsN: MS Fast-moving Watch Cells


Page 44

1.3.23 Hierarchical Handover

If Level HO Allowed is set to Yes, the inter-layer handover is allowed. To enable the

handover between different priorities of cells at the same layer, you also need to set

this parameter to Yes. If none of the high-speed railway fast handover, emergency

handover, enhanced dual-band network handover, load handover, edge handover,

and fast-moving micro-to-macro cell handover is triggered, the hierarchical handover

may be triggered if all the following conditions are met:

The priority level of the neighbor cell is higher than the serving cell.

The receive level of the BCCH in neighbor cell i after filtering meets the following

formula: _f layer layeriSS T H ＋

Where,

SSi_f indicates the receive level of the BCCH in the neighbor cell after filtering and

penalty.

Tlayer indicates Inter-layer HO Threshold.

Hlayer indicates Inter-layer HO Hysteresis.

The 16-bit sequence number of the neighbor cell is smaller thanthat of the serving cell. If the sequence number is small, the priorityof the cell is high.

If all these conditions are met during the period specified by Layer HO Valid Time(s)

within the latest Layer HO Watch Time(s), that is, if the P/N criterion is met, then the

hierarchical handover is triggered.

The following figure shows the procedure for the hierarchical handover decision.


Page 45

Procedure for the hierarchical handover decision

Start (MR input)

16-bit sequence number ofneighbor cell < that of serving

cell?

SSi_f>Tlayer+Hlayer andpriority of neighbor cell <priority of serving cell?

Yes

Meet P/Ncriterion?

SSi_f: Receive level of BCCH inneighbor cell after filtering

Tlayer: Inter-layer HO ThresholdHlayer: Inter-layer HO Hysteresis

No

No

No Whether the neighbor cell meets allprevious conditions within N out of P

P:Layer HO Valid Time(s)

N: Layer HO Watch Time(s)

Next neighborcell decision

Yes

Yes

Do candidatecells exist?

Inter-layerhandoverallowed?

No

No

Yes

Yes

End Triggerhierarchical handover

If Level HO Allowed set to Yes, inter-layer handover is allowed.

1.3.24 PBGT Handover

If PBGT HO Allowed is set to Yes, the PBGT handover is allowed. If none of the

high-speed railway fast handover, emergency handover, enhanced dual-band

network handover, load handover, edge handover, fast-moving micro-to-macro cell


Page 46

handover, and hierarchical handover is triggered, the PBGT handover (to the

neighbor cell with small path loss) may be triggered if all the following conditions are

met:

The neighbor cell (not the serving cell) has the same hierarchy asthe serving cell at the same layer.

For the neighbor cell, the following formula is met within the periodspecified by PBGT Valid Time(s) out of the period specified byPBGT Watch Time(s).

_ _ _ __ _ 2i f s f s_f ms i ms sSS DL SS DL Poff_DL P P Margin

Where,

SS_DLs_f indicates the receive level of the downlink TCH in the serving cell after

filtering.

SS_DLi_f indicates the receive level of the BCCH in neighbor cell i after filtering and

penalty.

Poff_DLs_f indicates the offset of the transmit power of the BTS on the downlink after

the filtering in the serving cell to the maximum transmit power on the TCH. The step is

2 dB.

Pms_i indicates the maximum transmit power of the MS in neighbor cell i. It is related

to the frequency band for neighbor cell i. Generally, GSM900/850, GSM1800, and

GSM1900 correspond to different transmit power.

Pms_s indicates the maximum transmit power of the MS in the serving cell. It is related

to the frequency band for the serving cell. Generally, GSM900/850, GSM1800, and

GSM1900 correspond to different transmit power.

Margin indicates the hysteresis to avoid ping-pong handovers. Accordingly, the

PBGT HO Threshold parameter can be configured to mean that the PBGT handover

to the neighbor cell is performed when the sum of the downlink level of neighbor cell

and the downlink level of the serving cell is greater than the value of PBGT HO

Threshold. When the value is smaller than 64, it indicates that the handover to the

neighbor cell whose level is lower than the serving cell can be performed.

The PBGT handover is triggered if the previous conditions are met and if the number


Page 47

of candidate 2G cells is not zero. The candidate cells are the neighbor cells with the

smallest 16-bit sequence number.

The following figure shows the procedure for the PBGT handover decision.


Page 48

Procedure for the PBGT handover decision

PBGT HO Allowed set to

End

Start (MR input)

N: PBGT Watch TimeP: PBGT Valid Time

Signalingchannel?

Yes

Yes

Is serving cell the enhanced dual-band network celland do neighbor cell and serving cell

belong to the same cell group?

candidate cell lower thanthat of serving cell?

Candidate cell and

Neighbor cell PBGT

Fast-movingmicro-macro cell

handoverdecision

Whether to trigger fast-moving micro-macro cell

handover?

Traverse all candidate

No

Traverse next neighbor cell

No

Yes

Yes

Yes

No

No

No

Trigger fast-movingmicro-macro cell

handover

Yes

No

Trigger PBGThandover

[SS_DLi_f -(SS_DLs_f +Poff_DLs_f ×2)]

- (Pms_i - Pms_s) > Margin ？

Update PBGTcounter

Yes

No

Meet conditons for PBGT handover

from enhanced dual-band cell to same

Yes

Yes No

No

Traversecomplete

Yes?

neighbor cells

group cell?

16-bit priority level of

serving cell have samepriority?

meets P/N criterion?

Conditions of PBGT handover from enhanceddual-band network cell to same group cell:

1) If MS in overlaid subcell and Out Cell

Load HO To Inn Cell Enable set to No

2) If MS in underlaid subcell and Out Cell

Load HO To Inn Cell Enable set to Noand enhanced dual-band network

overlaid-underlaid subcells handoverpenalty timer timed out or not started

Cell priority determinedby Layer of the Cell and

Cell Priority

SS_DLi_f: DL level of neighbor cell

SS_DLs_f: DL level of serving cell

Poff_DLs_f: BTS maximum TX power offset

Pms_i: MS maximum TX power in neighbor cell

Pms_s: MS maximum TX power in serving cellMargin: PBGT HO Thresho


Page 49

1.3.25 Concentric Cell Handover

The concentric cell handover is classified into normal concentric cell handover and

enhanced concentric cell handover. The current network mainly uses the enhanced

concentric cell handover and the ATCB algorithm applies to only the enhanced

concentric cell handover. Therefore, this part mainly describes the technology and

application of the enhanced concentric cell handover.

1.3.26 Normal Concentric Cell Algorithm

You can select the normal concentric cell handover or enhanced concentric cell

handover through Concentric Circles HO Allowed. If Concentric Circles HO Allowed

is set to NO, the normal concentric cell handover is enabled. At present, in the normal

concentric cell algorithm, the handover from the overlaid subcell to the underlaid

subcell is blind handover because the underlaid subcell level cannot be obtained.

Therefore, the handover success rate is low and this handover is rarely used for the

current network.

1.3.27 Enhanced Concentric Cell Algorithm

On the SDCCH− If Assign Optimum Layer is set to No Priority, handle

the assignment procedure according to the assignmentprocedure in the access load module.

− If Assign Optimum Layer is set to Overlaid Subcell,assign the TCHs to the overlaid subcell preferentially.

− If Assign Optimum Layer is set to Underlaid Subcell,assign the TCHs to the underlaid subcell preferentially.

− If Assign Optimum Layer is set to System Optimization,decide whether to assign TCHs to the overlaid subcellaccording to the uplink receive level and TA in the MRs from theSDCCH.

If the uplink receive level after filtering is greater than the value ofAssign-optimum-level Threshold and if the TA is smaller than the value of TAThreshold of Assignment Pref., assign the TCHs to the overlaid subcell.

On the TCH

The handover on the TCH is classified into the following: handover from the underlaid


Page 50

subcell to the overlaid subcell, handover from overlaid subcell to underlaid subcellcaused by low underlaid subcell load, and handover from the underlaid subcell to theoverlaid subcell due to MS movement.The triggering conditions are as follows:

None of the emergency handover, enhanced dual-band network handover, load

handover, edge handover, better cell handover, and PBGT handover is triggered.

The TCH is in the full-rate or half-rate state.

The attribute of the serving cell is concentric cell.

Handover from Underlaid Subcell to Overlaid Subcell− The decision conditions are as follows:

1. The penalty timer with duration of Penalty Time of UL to OL HO is timed out or is

not started.

2. Number of Failed Handovers from Underlaid Subcell to Overlaid Subcell < value of

MaxRetry Time after UtoO Fail

3. If RX_LEV for UO HO Allowed is set to Yes, the downlink receive level after

power control compensation is greater than the value of UL to OL HO Received

Level Thrsh.

4. If ATCBHoSwitch is set to Yes, then (downlink receive level of the primary BCCHin the underlaid subcell - downlink receive level of the neighbor cell whose level is thehighest) > value of Distance Between Out And Inn Cell boundary.

5. If RX_QUAL for UO HO Allowed is set to Yes, the downlink receive quality of

underlaid subcell after filtering < value of RX_QUAL Thrsh..

6. If TA for UO HO Allowed is set to Yes, the TA of underlaid subcell after filtering <

(TA Thrsh.- TA Hysteresis)

If all the previous conditions are met, the decision conditions of the handover from the

underlaid subcell to the overlaid subcell are met.

PN Criterion:

Within the period specified by UO HO Watch Time (s), if the decision conditions aremet for the period specified by UO HO Valid Time (s), the conditions of the handoverfrom the underlaid subcell to the overlaid subcell are met.

The following MS selection procedure is applicable to only the MS that meets the P/N

criterion.

MS Selection Procedure:


Page 51

MS selection procedure

Start (MRtrigger)

1. Evaluate cell loadperiodically

(1s)

2. Cell load > Out Cell GeneralOverLoad Thred

Return

3. Cell load > Out Cell SeriousOverLoad Thred

4. For adaptation, value of Load HO StepPeriod decreases by 1 per second.The minimum is 1 and the step

remains unchanged

5. Adjust handover margin

based on handover period and

6. MS inhandovermargin?

7. MS initiateshandover

Return

Return

Configure LoadHO Step

Period to setvalue

No

Yes

Yes

No

Yes

No

U to O Traffic HOallowed?

No

Yes

load adjustment step

Procedure Description:

The TCH usage of the underlaid subcell is greater than the value of En Iuo Out CellGeneral OverLoad Thred, and the MSs that meet the handover conditions are withinthe handover margin. The handover margin is stepped from the maximum level (-47dBm) to the boundary of the overlaid and underlaid subcells level by level. The aim is


Page 52

to hand over the MSs near the BTS to the overlaid subcell. If the TCH usage of theunderlaid subcell is greater than the value of En Iuo Out Cell Serious OverLoadThred, the period specified by En Iuo In Cell Load classification HO Period shouldbe shortened to enable the faster handover of the MSs in the underlaid subcell to theoverlaid subcell.

Handover from Overlaid Subcell to Underlaid Subcell Caused byLow Underlaid Subcell Load

Handover Procedure

Start

1. Evaluate cell loadperiodically

(1s)

2. Cell load < Out Cell Low Load ThredL_Thdload

Return

3. Adjust handover margin based onhandover period andload adjustment step

4. MS inhandovermargin?

5. MS initiateshandover

Return

Return

Yes

No

Procedure Description:

If the load of the underlaid subcell is lower than the value of En Iuo Out Cell LowLoad Thred and if the MS is within the handover margin, the handover from theoverlaid subcell to the underlaid subcell is triggered. The maximum range of thehandover margin is from OL to UL HO Received Level Thrsh. to the maximum level(-47 dbm). If En Iuo In Cell Load classification HO Period of the handover margin


Page 53

is stepped to the BTS from OL to UL HO Received Level Thrsh. for En Iuo In CellLoad classification HO Step, the MSs on the overlaid subcell boundary arepreferentially handed over to the underlaid subcell.

Handover from the Overlaid Subcell to the Underlaid Subcell DueTo MS Movement− Decision Conditions:

1. If RX_LEV for UO HO Allowed is set to Yes, the downlink receive level afterpower control compensation < value of OL to UL HO Received Level Thrsh.

2. If ATCBHoSwitch is set to Yes, (downlink receive level of the primary BCCH in the

underlaid subcell –downlink receive level of the neighbor cell whose level is the

highest) < (Distance Between Out And Inn Cell boundary - Distance Hyst

Between Out And Inn Cell Boundary)

3. If RX_QUAL for UO HO Allowed is set to Yes, the downlink receive quality of the

underlaid subcell after filtering > RX_QUAL Thrsh.

4. If TA for UO HO Allowed is set to Yes, the TA of the underlaid subcell after

filtering > (TA Thrsh. + TA Hysteresis)

If any one of the previous conditions are met, the decision conditions of the handover

from the overlaid subcell to the underlaid subcell are met.

PN Criterion:

Within the period specified by UO HO Watch Time (s), the decision conditions are

met for the period specified by UO HO Valid Time (s), the conditions of the handover

from the overlaid subcell to the underlaid subcell are met.

Target Cell Selection:

The cell that has a favored 16-bit sequence ranking can be an underlaid subcell or a

neighbor cell.

1.3.28 AMR Handover


dual-band network handover, load handover, fast-moving micro-to-macro cell

handover, hierarchical handover, PBGT handover, concentric cell handover is

triggered, and if both Intracell HO Allowed and Intracell F-H HO Allowed are set to


Page 54

Yes, the AMR handover may be triggered if all the following conditions are met:

1.3.29 Handover from TCHF to TCHH

RQI/2 of the serving cell after filtering > value of F2H HO th

1.3.30 Handover form TCHH to TCHF

RQI/2 of the serving cell after filtering < value of H2F HO th

Within the period specified by Intracell F-H HO State Time, if the triggering

conditions are met for the period specified byIntracell F-H HO State Time, the P/N

criterion is met and the handover is triggered. Note: The previous two parameters are

also used for the handover from TCHH to TCHF.

The following figure shows the procedure for the handover:


Page 55

Procedure for the AMR handover

Start

Are both INTRAHO andINTRAFHHO set to Yes?

Handover triggered?

TCH and speech version 3?

INTRAHO: Intra-Cell Handover Allowed

INTRAFHHO: Intracell F-H HO Allowed

Full-rate TCH? andAMR TCH/H Prior Allowed?

and cell load lower than threshold?

Yes

Yes

Yes

AMR processing and concentriccell ping-pong handover

protection processing

No

Ping-pong protectionprotection for highly

loaded cell

Protectionprocessing in

underlaid subcell

RQI/2 of the serving cell afterfiltering > value of F2H HO th

Full-rate TCH? Half-rate TCH?

P/N criterion met?

Yes

Yes

Yes

RQI/2 of the servingcell after filtering >

value of H2F HO thh

Protection processingin overlaid subcell

Intra-cell AMRhandover istriggered.

End

Yes

Yes

No

No

No

No

No

Yes

Yes

No

End

No

P: Intracell F-H HO State TimeN: Intracell F-H HO State Time

The AMR handover failure timerhas not expired with the value

specified by Penalty Time afterAMR TCHF-H HO Fails?

1.3.31 Better 3G Cell Handover



Page 56

dual-band network handover, load handover, edge handover, fast-moving

micro-to-macro cell handover, hierarchical handover, PBGT handover, concentric cell

handover, and AMR handover is triggered, the procedure for the better 3G cell

handover is triggered, as shown in the following figure:

Procedure for the better 3G cell handover

Start

Handover triggered?

HOSYS is set to No?or are 3G better cell parameters set to 0?

FDD set to No?and TDD is set to No?

MTYPE is RSCP andRSCPi_f is greater than RSCP?

or MTYPE is Ec/N0 andEcNoi_f is greater than Ec/No?

FDD: Better 3G Cell HO Allowed

TDD: TDD Better 3G Cell HO Allowed

Processescandidate 3G

cell list

Current cell type is FDD？and MS supports FDD？

MTYPE:FDD REP QUANTRSCP: FDD RSCP Threshold for Better 3G CELL HO

RSCPi_f: measured value of FDD RSCP after filterinEc/N0: FDD Ec/No Threshold for Better 3G CELL HO

EcNoi_f: measured value of FDD Ec/No after filtering

TDDRSCP:TDD RSCP Threshold for Better 3G CELL HO

TDDRSCPi_f: measured value of TDD RSCP after filteringTDDRSCPi_f大于TDDRSCP？

Current cell type is TDD?and MS supports TDD?

Are the FDD P/FDD criteriamet?

Are the TDD P/TDD Ncriteria met?

FDD P: 3G Better Cell HO Valid Time

FDD N: 3G Better Cell HO Watch Time

TDD P:T DD 3G Better Cell HO Valid Time

TDD N: TDD 3G Better Cell HO Watch Time

3G better cellhandover is

triggered.

End

End

No

No

Yes

No

Yes

No

No

No

No

Yes

Yes

Yes

Yes

Yes

Yes

Yes

HOSYS: Outgoing-RAT HO Allowed

For the FDD handover, whether to measure RSCP or Ec/No is selected on the basis

of FDD REP QUANT. The TDD supports only the measurement of the RSCP.

If the RSCP or Ec/No of a certain measurement period meets the conditions, one

valid measurement is calculated. If the persistent measurement results meet the P/N

criterion, the better 3G cell handover is triggered.


Page 57

1.3.32 Directed Retry

If the TCH assignment in the cell fails, the TCH assignment and handover procedure

is completed through the selection of new target cell via directed retry algorithm when

the MS has occupied the SDCCH (single signaling connection state) and Direct

Retry is set to Yes.

For directed retry, the procedure for selection of candidate cells is as follows: The

cells and serving cells that do not meet the necessary handover conditions based on

the handover type are removed from the cell queue after basic sorting. Then, the

directed retry procedure is initiated on the cell that has the smallest 16-bit sequence

number among the candidate cells.

1.3.33 Handover in Single-Signaling /SDCCH State

The handover decision for the MS that has occupied the SDCCH is the same as that

for the MS that has occupied the TCH. In other words, the TA handover, interference

handover, bad quality handover, quick drop handover, edge handover are allowed,

but the load handover, PBGT handover, concentric cell handover, and AMR

handover are prohibited. In addition, the parameters for the handover decision are

the same as TCH parameters. If SDCCH HO Allowed is set to Yes, the handover

between signaling channels is allowed. The measurement for the MS that has

occupied the SDCCH uses different filtering parameters from that for the MS that has

occupied the TCH.

1.3.34 Handover Implementation

In the handover implementation procedure, the Handover Power Boost Switch

parameter is used to determine whether the BTS of the serving cell uses the

maximum transmit power during the handover. If this parameter is set to Yes, the

transmit power of the BTS is set to the maximum value before the BSC sends the


Page 58

handover command to the MS. In addition, the BTS power is not adjusted during the

handover to ensure the success of the handover.

The handover implementation procedure uses the protocol procedure for the

standard interfaces.

2 Parameters Involved in the Algorithms

2.1 Parameters detail description

2.1.1 Co-BSC/MSC Adj

Description: This parameter determines whether the sequence of candidate cells is

adjusted. After the sequence is adjusted, the handover within the same BSC/MSC

takes priority.

Value range: Yes, No

Unit: none

Default value: Yes

Configuration policy: If this parameter is set to Yes, the target cell to which the MS is

handed over may not be the cell with the best signal quality.

Relevant algorithm: algorithms of all the handovers except intra-cell handovers,

such as the AMR handover and concentric cell handover

2.1.2 SDCCH HO Allowed

Description: This parameter determines whether a handover between signaling

channels is enabled.


Unit: none

Default value: No

Configuration policy: When the authentication and ciphering procedure is enabled,

this parameter can be set to Yes.


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Relevant algorithm: algorithms of all the handovers except the load handover,

PBGT handover, concentric cell handover, and AMR handover

2.1.3 Penalty Allowed

Description: This parameter determines whether a penalty is performed for the

target cell where a handover fails or for the serving cell where the TA is too great or

the signal quality is too bad.


Unit: none

Default value: Yes

Configuration policy: Huawei recommends that this parameter be set to Yes. If you

need to disable the penalty for a certain handover, set the related penalty time and

penalty level to 0.

Relevant algorithm: all algorithms

2.1.4 MS Power Prediction after HO

Description: This parameter determines whether an MS can use the optimum

transmit power instead of the maximum transmit power to gain access to the new

channel after a handover. The purpose is to reduce interference and improve the

service quality.


Unit: none

Default value: No

Configuration policy: If this parameter is set to Yes, the MS does not use the

maximum transmit power, and thus the handover success rate is decreased, but the

network interference is reduced.



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2.1.5 Power Level for Direct Try

Description: This parameter is used to select the candidate cells during directed

retry.

Value range: 0–63

Unit: dBm; physical value range: -110 dBm to -47 dBm

Default value: 16

Configuration policy: If the RX level of a neighbor cell exceeds the value of this

parameter, the neighbor cell is selected as the candidate cell for directed retry.

Relevant algorithm: directed retry

2.1.6 Allowed MR Number Lost

Description: This parameter determines the number of successive measurement

reports allowed to be lost. If the number of successive measurement reports lost is

equal to or smaller than the value of this parameter, the last two measurement

reports received are gathered and the lost measurement report is estimated based on

the linear interpolation. If the number of successive measurement reports lost is

greater than the value of this parameter, all previous measurement reports are

discarded, and calculations are made again when new measurement reports are

received.

Value range: 0–31

Unit: none

Default value: 4

Configuration policy: Measurement reports fail to be decoded correctly when the

signal quality in the serving cell is poor. When this threshold is exceeded, all previous

measurement reports are discarded and the handover may fail. Therefore, Huawei

recommends that this parameter be set to a great value for emergency handovers.



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2.1.7 RscPenaltyTimer

Description: This parameter determines the value of the timer used for neighbor cell

penalty after handover failure due to cell congestion.

Value range: 0–255

Unit: seconds

Default value: 5

Configuration policy: If this parameter is set to a high value, the target cell for the

previous handover will not be selected for the next handover, but the probability of

call drops increases. If this parameter is set to a low value, the probability of handover

failure increases.

Relevant algorithm: all handover algorithms

2.1.8 UmPenaltyTimer


penalty after handover failure due to the Um interface error.


Unit: seconds

Default value: 10




failure increases.


2.1.9 CfgPenaltyTimer


penalty after handover failure due to data configuration.


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Unit: seconds

Default value: 255




failure increases.


2.1.10 MR Preprocessing

Description: This parameter determines whether measurement reports are

preprocessed by the BTS.


Unit: none

Default value: No

Configuration policy: If this parameter is set to Yes, the signaling on the Abis

interface and the load of the BSC are reduced. Thus, the response time is reduced and

the network performance is improved. If this parameter is set to No, the measurement

reports are preprocessed by the BSC. In this case, the three parameters Transfer

Original MR, Transfer BS/MS Power Class, and Sent Freq.of Preprocessed MR

are invalid.


2.1.11 Transfer Original MR

Description: This parameter determines whether the BTS should send the original

measurement report to the BSC.


Unit: none


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Default value: No

Configuration policy: In 4:1 multiplexing mode, if there are more than two

timeslots configured in SDCCH/8 scheme, then this parameter should be set to No.


2.1.12 Transfer BS/MS Power Class

Description: This parameter determines whether the BS/MS power class should be

transferred from the BTS to the BSC.


Unit: none

Default value: Yes

Configuration policy: When MR preprocessing is enabled, the UL and DL balance

measurement is affected if Transfer BS/MS Power Class is set to No. Additionally,

the handovers (such as PBGT handovers, load handovers, and concentric cell

handovers) that require power interpolation may become abnormal.


2.1.13 Sent Freq of Preprocessed MR

Description: After preprocessing the measurement reports, the BTS sends them to

the BSC.

Value range: Do not Report, Twice every second, Once every second, Once every

two seconds, Once every four seconds

Unit: none

Default value: Twice every second, Once every second (for 4:1 configuration)

Configuration policy: None.



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2.1.14 Report Type

Description: After preprocessing the measurement reports, the BTS sends them to

the BSC.

Value range: Common Measurement Report, Enhanced Measurement Report

Unit: none

Default value: Common Measurement Report

Configuration policy: The Enhanced Measurement Report supports the

measurement of the 3G neighbor cells to realize the interoperability between the 2G

system and the 3G system, and thus ensures the service continuity.


2.1.15 DtxMeasUsed

Description: This parameter is used as the switch for controlling the value

determination method of measurement reports. 0: off; 1: on

Value range: 0, 1

Unit: none

Default value: 1

Configuration policy: When this parameter is set to 0, if the measurement report

indicates that DTX is not used, the FULLSET values should be selected; if the

measurement report indicates that DTX is used, the SUBSET values should be

selected. In the latter case, the SUBSET values should be used irrespective of how

DTX is indicated in the subsequent measurement reports. When this parameter is set

to 1, the FULLSET or SUBSET values should be used according to the DTX

indication bit in the measurement report. That is, if the measurement report indicates

that DTX is used, the SUBSET values should be selected; otherwise, the FULLSET

values should be selected.



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2.1.16 Allowed MR Number Lost

Description: This parameter determines the number of successive measurement

reports allowed to be lost.

Value range: 0–31

Unit: none

Default value: 4

Configuration policy: Measurement reports fail to be decoded correctly when the

signal quality in the serving cell is poor. When this threshold is exceeded, all previous

measurement reports are discarded and the handover may fail. Therefore, Huawei

recommends that this parameter be set to a great value for emergency handovers.

Thus, it is advised to set this parameter with a greater value to enable emergency

handover.


2.1.17 Filter Length for SDCCH Level

Description: This parameter determines the number of measurement reports used

for averaging the signal strength on the SDCCH.

Value range: 1–31

Unit: none

Default value: 2

Configuration policy: This parameter should be set to a small value because the

SDCCH seizure duration is shorter than the TCH seizure duration for the MS.

Relevant algorithm: filtering processing of measurement reports

2.1.18 Filter Length for TCH Level


for averaging the speech/data TCH signal strength.


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Value range: 1–31

Unit: none

Default value: 4

Configuration policy: This parameter helps to avoid sharp drop of signal levels

caused by Raileigh Fading and to ensure correct handover decisions. When this

parameter is set to a higher value, the impact of sudden changes is reduced, and the

system response is delayed. Thus, the network performance is degraded.


2.1.19 Filter Length for SDCCH Qual


for averaging the SDCCH quality.

Value range: 1–31

Unit: none

Default value: 2

Configuration policy: This parameter should be set to a small value because the

SDCCH seizure duration is shorter than the TCH seizure duration for the MS.


2.1.20 Filter Length for TCH Qual


for averaging the speech/data TCH signal quality.

Value range: 1–31

Unit: none

Default value: 4

Configuration policy: When this parameter is set to a higher value, the impact of

sudden changes is reduced, and the system response is delayed. Thus, the network

performance is degraded.


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2.1.21 Filter Length for TA


for averaging the timing advance.

Value range: 1–31

Unit: none

Default value: 4

Configuration policy: When this parameter is set to a higher value, the impact of

sudden changes is reduced, and the system response is delayed. Thus, the network

performance is degraded.


2.1.22 Filter Length for Ncell RX_LEV


for averaging the timing advance.

Value range: 1–31

Unit: none

Default value: 4

Configuration policy: This parameter determines the number of measurement

reports used for averaging the signal strength in neighbor cells. This parameter helps

to avoid sharp drop of signal levels caused by Raileigh Fading and to ensure correct

handover decisions.

When this parameter is set to a higher value, the impact of sudden changes is

reduced, and the system response is delayed. Thus, the network performance is

degraded.



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2.1.23 Penalty Level after TA HO

Description: This parameter determines the penalty on the signal strength of the

original serving cell to avoid ping-pong handovers after an emergency handover due

to timing advance is performed. This parameter is valid only within the Penalty Time

after TA HO.

Value range: 0–63

Unit: none

Default value: 63

Configuration policy: If this parameter is set to a lower value, it is easy for the MS to

be handed over to the original serving cell, thus leading to ping-pong handovers. If

this parameter is set to a higher value, it is difficult for the MS to be handed over to

the original serving cell.

Relevant algorithm: TA handover algorithm

2.1.24 Penalty Time after TA HO(s)

Description: This parameter determines the duration of the penalty imposed on the

original serving cell after an emergency handover due to timing advance is

performed.


Unit: seconds

Default value: 30







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2.1.25 Penalty Level after BQ HO

Description: This parameter determines the penalty level imposed on the original

serving cell after an emergency handover due to bad signal quality is performed. The

penalty level is imposed to avoid ping-pong handovers.

Value range: 0–63

Unit: none

Default value: 63





Relevant algorithm: bad quality handover algorithm

2.1.26 Penalty Time after BQ HO (s)

Description: This parameter determines the duration of the penalty imposed on the

original serving cell after an emergency handover due to bad signal quality is

performed.


Unit: seconds

Default value: 15





Relevant algorithm: bad quality handover algorithm


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2.1.27 Penalty Level after HO Fail

Description: This parameter determines the penalty level imposed on the target cell.

A penalty level is imposed on the target cell to avoid further handover attempts to the

cell when a handover fails for any of the following reasons: cell congestion, a

message indicating internal handover refusal is received, a message indicating Um

interface handover failure is received during the outgoing BSC handover, and a

message indicating Um interface handover failure is received during the internal

handover. This parameter is valid only before the penalty time of handover failure

expires.

Value range: 0–63

Unit: none

Default value: 30


be handed over to the cell where the previous handover fails, thus leading to another

handover failure. If this parameter is set to a higher value, it is difficult for the MS to

be handed over to the cell where the previous handover fails.


2.1.28 Penalty Time after HO Fail(s)

Description: This parameter determines the period in which penalty is imposed on

the neighbor cells of the cell where a fast-moving MS is located. The neighbor cells

must be located at the Macro, Micro, or Pico layer other than the Umbrella layer.


Unit: seconds

Default value: 10


be handed over to the cell where the previous handover fails, thus leading to another

handover failure. If this parameter is set to a higher value, it is difficult for the MS to


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be handed over to the cell where the previous handover fails.


2.1.29 Penalty on MS Fast Moving HO

Description: This parameter determines the penalty on the level of the original

serving cell after the fast-moving micro-to-macro cell handover is successful. The

penalty is performed only when the MS is located at the Umbrella layer and the

neighbor cells are located at the Macro, Micro, or Pico layer. This parameter is valid

only within the Penalty Time on Fast Moving HO.

Value range: 0–63

Unit: none

Default value: 30


be handed over to the micro cell again, thus leading to ping-pong handovers. If this

parameter is set to a higher value, it is difficult for the MS to be handed over to the

micro cell.

Relevant algorithm: fast-moving micro-to-macro cell handover algorithm

2.1.30 Penalty Time on Fast Moving HO

Description: This parameter determines the penalty time imposed on the original

serving cell after the fast-moving micro-to-macro cell handover is successful.


Unit: seconds

Default value: 40


be handed over to the micro cell again, thus leading to ping-pong handovers. If this

parameter is set to a higher value, it is difficult for the MS to be handed over to the

micro cell.


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2.1.31 Quick Handover Punish Value

Description: This parameter determines the penalty on the downlink level of the

original serving cell after the high-speed railway fast handover is successful.

Value range: 0–63

Unit: none

Default value: 30





Relevant algorithm: high-speed railway fast handover algorithm

2.1.32 Quick Handover Punish Time

Description: This parameter determines the duration of penalty on the original

serving cell after the high-speed railway fast handover is successful.


Unit: seconds

Default value: 10





Relevant algorithm: high-speed railway fast handover algorithm

2.1.33 Inter-BSC SDCCH HO Allowed

Description: This parameter determines whether the inter-BSC SDCCH handover is


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enabled.


Unit: none

Default value: No

Configuration policy: This parameter should be set to Yes when the inter-BSC

SDCCH handover is allowed.


2.1.34 Min DL Level on Candidate Cell

Description: The M criterion supports the minimum value constraint of downlink RX

level of the neighbor cell.

Value range: 0–63 (corresponding to –110 dBm to –47 dBm)

Unit: none

Default value: 15

Configuration policy: 1. This parameter must be properly specified because it limits

the number of candidate cells. If this parameter is set to a higher value, some desired

cells may be excluded from the candidate cells. If this parameter is set to a lower

value, an unwanted cell may become a candidate cell. This leads to handover failures

or call drops. 2. A cell can become a candidate cell only when the RX level minus this

parameter is greater than the minimum access level offset.


2.1.35 HOCdCellMinUpPwr

Description: The M criterion supports the minimum value constraint of uplink RX


Value range: 0–63 (corresponding to –110 dBm to –47 dBm)

Unit: none

Default value: 10


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Configuration policy: 1. This parameter must be properly specified because it limits

the number of candidate cells. If this parameter is set to a higher value, some desired

cells may be excluded from the candidate cells. If this parameter is set to a lower

value, an unwanted cell may become the target cell. This leads to handover failures

or call drops. 2. A cell can become a candidate cell only when the uplink RX level

minus this parameter is greater than the minimum access level offset.


2.1.36 Min Access Level Offset

Description: The M criterion supports the minimum value constraint of uplink RX


Value range: 0–63

Unit: none

Default value: 0

Configuration policy: The offset is set based on Min DL Level on Candidate Cell

and Min UL Level on Candidate Cell. Different offsets can be set for different

neighbor cells. To become a candidate cell, a neighbor cell must meet the following

requirements:

Expected uplink level of the neighbor cell >= (minimum uplink power of the candidate

cell for handover + minimum access level offset)

Expected downlink level of the neighbor cell >= (minimum downlink power of the

candidate cell for handover + minimum access level offset)


2.1.37 K Bias

Description: This parameter determines the bias for cell sorting based on the

K criterion.


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Value range: 0–63

Unit: none

Default value: 0

Recommended value: none

Configuration policy: Before the downlink RX level of the candidate cells is

sorted based on the K criterion, K Bias is subtracted from the actual downlink

RX level of the candidate cells. This parameter affects the result of cell sorting.

This parameter is usually set to 0.


2.1.38 UTRAN Cell Type

Description: This parameter determines the type of a 3G cell.

Value range: 0, 1

Unit: none

Default value: 0

Configuration policy: This parameter determines the type of a 3G cell. Value 0

indicates an FDD cell and value 1 indicates a TDD cell.


2.1.39 FDD REP QUANT

Description: FDD measurement report index

Value range: RSCP–0, EcNo–1

Unit: none

Default value: RSCP

Configuration policy: Ec/No means Signal Noise Ratio in WCDMA. It maps with C/I


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in GSM.

RSCP is short for Received Signal Code Power.


2.1.40 Min RSCP Threshold

Description: This parameter determines the selection of 3G candidate cells.

Value range: 0–63

Unit: none

Default value: 10

Configuration policy: This parameter must be properly specified because it limits

the number of candidate cells for handovers. If this parameter is set to a higher value,

some desired cells may be excluded from the candidate cells. If this parameter is set

to a lower value, an unwanted cell may become a candidate cell. This leads to

handover failures or call drops.


2.1.41 Min Ec/No Threshold

Description: This parameter determines the selection of 3G candidate cells.

Value range: 0–49

Unit: none

Default value: 10

Configuration policy: This parameter must be properly specified because it limits

the number of candidate cells for handovers. If this parameter is set to a higher value,

some desired cells may be excluded from the candidate cells. If this parameter is set

to a lower value, an unwanted cell may become a candidate cell. This leads to

handover failures or call drops.



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2.1.42 RSCPOff

Description: RSCP is short for Received Signal Code Power. It is a performance

counter of the 3G cells.

Value range: 0–63

Unit: none

Default value: 3

Configuration policy: When both Outgoing-RAT HO Allowed and Better 3G Cell

HO Allowed are set to Yes, if the RSCP of a 3G neighbor cell is greater than RSCP

Threshold for Better 3G Cell HO during a period of time, then the 3G cell is selected

as a candidate cell.


2.1.43 EcNoOff

Description: Ec/No indicates the ratio of received energy per chip to noise spectral

density. It is a performance counter of the 3G cells.

Value range: 0–63

Unit: none

Default value: 3

Configuration policy: When both Outgoing-RAT HO Allowed and Better 3G Cell

HO Allowed are set to Yes, if the Ec/No of a 3G neighbor cell is greater than Ec/No

Threshold for Better 3G CELL HO plus this parameter during a period of time, then

the 3G cell is selected as a candidate cell.


2.1.44 Inter-layer HO Threshold

Description: This parameter is one bit of the 16 bits that are used by the BSC to sort

the candidate cells for handovers.


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Value range: 0–63

Unit: none

Default value: 25

Configuration policy: For the hierarchical handover and load handover, the RX level

of the target cell must be higher than the Inter-layer HO Threshold. Otherwise, the

MS may be handed over from a cell with high load (high priority) and high level to a

cell with low load (low priority) and low level, thus leading to call drops.


2.1.45 Inter-layer HO Hysteresis

Description: This parameter determines the hysteresis of the inter-layer handover.

This parameter and Inter-layer HO Threshold affect cell sorting and the inter-layer

handover.

Value range: 0–63

Unit: none

Default value: 3

Configuration policy: This parameter determines the hysteresis of an inter-layer or

inter-priority handover. This parameter is used to avoid inter-layer ping-pong

handovers. Actual Inter-layer HO Threshold of a serving cell = configured Inter-layer

HO Threshold - Inter-layer HO hysteresis. Actual Inter-layer HO Threshold of a

neighbor cell = configured Inter-layer HO Threshold + Inter-layer HO hysteresis.


2.1.46 Inter-cell Handover Hysteresis

Description: This parameter determines the hysteresis of the handover between

neighbor cells at the same layer.

Value range: 0–63

Unit: none


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Default value: 5

Configuration policy: This parameter determines the hysteresis of the handover

between neighbor cells at the same layer. This parameter is set to avoid ping-pong

handovers. If the cells are at different layers, this parameter is invalid. The value of

this parameter needs to be adjusted according to the statistics of the handover

performance and the actual network. Flexible adjustment of the value of this

parameter has a positive effect on the handover and traffic between two neighbor

cells.


2.1.47 Min Interval for TCH Hos

Description: When a new TCH is assigned, a timer is started. The TCH can be

handed over only when the timer expires. This parameter is used to avoid unwanted

handovers due to inaccurate measurement reports generated in the initial phase of

call establishment.

Value range: 0–60

Unit: seconds

Default value: 2

Configuration policy: If the measurement report is processed by the BTS, set this

parameter to a relative small value. If the measurement report is processed by the

BSC, set this parameter to a relative great value.

Relevant algorithm: all handover algorithms except the high-speed railway fast

handover algorithm

2.1.48 Min Interval for SDCCH Hos

Description: When a new SDCCH is assigned, a timer is started. The SDCCH can

be handed over only when the timer expires. This parameter is used to avoid

unwanted handovers due to inaccurate measurement reports generated in the initial


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phase of call establishment.

Value range: 0–60

Unit: seconds

Default value: 2

Configuration policy: If the measurement report is processed by the BTS, set this

parameter to a relative small value. If the measurement report is processed by the

BSC, set this parameter to a relative great value.

Relevant algorithm: all handover algorithms except the high-speed railway fast

handover algorithm

2.1.49 Min Interval for Consecutive Hos

Description: This parameter determines the minimum interval between two

consecutive handovers. No handover is allowed during the minimum interval. A timer

starts after a handover is complete, and a subsequent handover is allowed only after

the timer expires.

The value of this parameter is the value of the timer. The parameter is used to avoid

frequent handovers.

Value range: 0–60

Unit: seconds

Default value: 4

Configuration policy: If this parameter is set to a lower value, frequent handovers

cannot be avoided. If this parameter is set to a higher value, handovers cannot be

performed timely.


2.1.50 Min Interval for Emerg Hos

Description: This parameter determines the minimum interval between two

consecutive emergency handovers. No emergency handover is allowed during the


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minimum interval. When the conditions for an emergency handover are met, an

emergency handover timer is started. Another emergency handover can be decided

only when the timer expires.

Value range: 0–60

Unit: seconds

Default value: 4

Configuration policy: If this parameter is set to a lower value, frequent handovers

cannot be avoided. If this parameter is set to a higher value, handovers cannot be

performed timely.


2.1.51 MS Fast-moving Time Threshold

Description: The time threshold is calculated based on the cell radius (r) and the

velocity (v). The threshold equals 2r/v. If the time for passing a cell is smaller than this

threshold, the MS is regarded as moving fast. Otherwise, the MS is regarded as

moving slow.


Unit: seconds

Default value: 15

Configuration policy: When the cell radius is fixed, the smaller the value of this

parameter is (the required velocity is higher), the more difficult for the fast-moving

micro-to-macro cell handover to be triggered.


2.1.52 Max Consecutive HO Times

Description: This parameter determines the maximum number of consecutive

intra-cell handovers allowed. If the interval between two continuous intra-cell

handovers is smaller than a specified threshold, the two handovers are regarded as


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consecutive handovers. If multiple consecutive intra-cell handovers occur, the

intra-cell handover is forbidden for a period.

Value range: 1–20

Unit: times

Default value: 3

Configuration policy: If this parameter is set to a smaller value, the intra-cell

handover may not be timely; if this parameter is set to a greater value, the system

resources may be wasted when intra-cell handovers occur frequently.

Relevant algorithm: Intra-cell handover algorithms (AMR handover algorithm, BQ

handover algorithm, and interference handover algorithm)

2.1.53 Forbidden Time after Max Times

Description: When the number of consecutive handovers allowed reaches the

maximum, a timer is started to forbid the intra-cell handover. Intra-cell handovers is

allowed only when the timer expires.


Unit: seconds

Default value: 20

Configuration policy: You can set this parameter to disable the intra-cell handover

for a certain period.



2.1.54 Interval for Consecutive HO Jud.

Description: The two intra-cell handovers that occur during the period specified by

this parameter are regarded as consecutive.


Unit: seconds


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Default value: 6

Configuration policy: This parameter, together with Forbidden Time after Max

Times, determines the frequency of intra-cell handovers.



2.1.55 DtxMeasUsed

Description: This parameter determines whether the DTX is used in the

measurement report. If this parameter is set to 1, the measurement results are taken

according to the DTX indicator in each measurement report; if this parameter is set to

0, the method used in the previous measurement report is adopted. During a calling

procedure, if the DTX is used for once, the DTX is used in all the subsequent

measurement reports.

0: DTX is not used

1: DTX is used

Value range: 0–1

Unit: none

Default value: 1



2.1.56 Max Resend Times of Phy Info

Description: During asynchronous handover, the MS constantly sends handover

access bursts to the BTS. Usually, the Timer T3124 lasts 320 ms. Upon detecting the

bursts, the BTS returns physical information to the MS through the main

DCCH/FACCH and sends the MSG_ABIS_HO_DETECT message to the BSC.

Meanwhile, the timer T3105 starts. The physical information containing information

on different physical layers guarantees correct MS access. If the timer T3105 expires


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before the BTS receives the SAMB frame from the MS, the BTS retransmits the

physical information to the MS.

This parameter determines the maximum times of retransmitting the physical

information, that is, Ny1. If the number of retransmissions exceeds Ny1 before the

BTS receives any correct SAMB frame, the BTS sends the BSC a connection failure

message, which also indicates handover failure. After receiving the message, the

BSC releases the newly assigned dedicated channel and stops the timer T3105. For

details, refer to the GSM 08.58 and the GSM 04.08.


Unit: times

Default value: 30

Configuration policy: You can increase the value of this parameter when handover

becomes slow or the success rate is lowered due to clock problems or poor

transmission.

An MS can be handed over only when Max Resend Times of Phy Info x Radio

Connection Timer is greater than the interval between EST IND and HO DETECT

(120–180 ms). Otherwise, the handover fails.


2.1.57 T3105 (10ms)

Description: This parameter indicates the timer T3150. For details, refer to the GSM

08.58 and the GSM 04.08.

When the BTS sends physical information to the MS, the BTS starts the timer T3105.

If T3105 expires before the BTS receives the SAMB frame from the MS, the BTS

retransmits the physical information to the MS and restarts the timer T3105. The

maximum number of times for retransmitting the physical information is Ny1.


Unit: ms


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Default value: 7

Configuration policy: The physical information is sent over the FACCH. Four TDMA

frames are sent each time at the interval of 18 ms. If the value of T3105 is smaller

than or equal to 18 ms, the BTS needs to retransmit the physical information to the

MS when the timer T3105 expires for the first time. If the transmission of the physical

information over the FACCH is not complete, the expiration is invalid because the

time is shorter than an FACCH period. Therefore, 20 is the reasonable minimum

value for this parameter. At present, the default value of this parameter is 70.


2.1.58 No Dl Mr. HO Allowed

Description: This parameter is used to control the handover algorithm based on the

measurement reports without the downlink information. If this parameter is set to No,

the handover algorithm based on the measurement reports without the downlink

information is disabled, and the handover decision based on the measurement

reports without the downlink information is not allowed in the cell. If this parameter is

set to Yes, the handover algorithm based on the measurement reports without the

downlink information is enabled, and the handover decision based on the

measurement reports without the downlink information is allowed in the cell.


Unit: none

Default value: none

Configuration policy: This parameter is set according to the traffic volume.

Relevant algorithm: no downlink measurement report handover algorithm

2.1.59 Cons. No Dl Mr. HO Allowed Limit

Description: This parameter determines whether the decision on the handover

based on the measurement reports without the downlink information is allowed. Each


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call is configured with a global timer, which counts the number of consecutive

measurement reports without the downlink information. When the timer exceeds this

threshold, the handover is disabled and the timer is reset.

Value range: 0–64

Unit: none

Default value: 8

Configuration policy: If the number of consecutive measurement reports without the

downlink information exceeds this threshold, the decision on the handover based on

the measurement reports without the downlink information is not performed.

Therefore, if this parameter is set to a smaller value, the handover based on the

measurement reports without the downlink information cannot be triggered.


2.1.60 No Dl Mr. Ul Qual HO Limit

Description: This parameter determines the uplink receive quality threshold for

triggering an emergency handover based on the measurement reports without the

downlink information. The handover decision is allowed only when the filtered uplink

receive quality is greater than No Dl Mr. Ul Qual HO Limit. Otherwise, the handover

decision is not allowed. When an emergency handover based on the measurement

reports without the downlink information is triggered, an inter-cell handover is

preferred. An intra-cell handover is triggered if no candidate cell is available and if

intra-cell handovers are allowed.

Value range: 0–70 (RQ (0–7) x 10)

Unit: none

Default value: 60

Configuration policy: The handover decision is allowed only when the uplink

receive quality is greater than this threshold. Therefore, if this parameter is set to a

greater value, the handover based on the measurement reports without the downlink


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information cannot be triggered.


2.1.61 TA HO Allowed

Description: This parameter determines whether the time advance (TA) handover is

enabled.


Unit: none

Default value: Yes



2.1.62 TA Threshold

Description: An emergency handover is triggered when TA is greater than or equal

to the value of this parameter.


Unit: bit period (A bit period corresponds to 0.55 km.)

Default value: 255

Configuration policy: This parameter determines the cell coverage for triggering the

TA emergency handover. In the areas with small space between BTSs and densely

distributed BTSs, the coverage of the cell can be reduced if this parameter is set to a

smaller value.


2.1.63 Interference HO Allowed

Description: This parameter determines whether the interference handover is

enabled.



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Unit: none

Default value: Yes


Relevant algorithm: interference handover algorithm

2.1.64 RXQUAL1

Description: If the receive level of the serving cell is smaller than or equal to 30, an

interference handover is triggered when the uplink or downlink quality of the cell is

greater than this threshold.

Value range: 0–70 (RQ (0–7) x 10)

Unit: none

Default value: 70

Configuration policy: This parameter is used in handover decision. An uplink

interference handover is easily triggered if this parameter is set to a smaller value.


2.1.65 RXQUAL2

Description: If the receive level of the serving cell is 31, an interference handover is

triggered when the uplink or downlink quality of the cell is greater than this threshold.

Value range: 0–70 (RQ (0–7) x 10)

Unit: none

Default value: 60




2.1.66 RXQUAL3

Description: If the receive level of the serving cell ranges from 32 to 35, an


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Value range: 0–70 (RQ (0–7) x 10)

Unit: none

Default value: 59




2.1.67 RXQUAL4




Value range: 0–70 (RQ (0–7) x 10)

Unit: none

Default value: 58




2.1.68 RXQUAL5




Value range: 0–70 (RQ (0–7) x 10)

Unit: none

Default value: 57



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2.1.69 RXQUAL6




Value range: 0–70 (RQ (0–7) x 10)

Unit: none

Default value: 56




2.1.70 RXQUAL7




Value range: 0–70 (RQ (0–7) x 10)

Unit: none

Default value: 55




2.1.71 RXQUAL8




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Value range: 0–70 (RQ (0–7) x 10)

Unit: none

Default value: 54




2.1.72 RXQUAL9




Value range: 0–70 (RQ (0–7) x 10)

Unit: none

Default value: 53




2.1.73 RXQUAL10




Value range: 0–70 (RQ (0–7) x 10)

Unit: none

Default value: 52




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2.1.74 RXQUAL11




Value range: 0–70 (RQ (0–7) x 10)

Unit: none

Default value: 51




2.1.75 RXQUAL12

Description: If the receive level of the serving cell is greater than or equal to 63, an



Value range: 0–70 (RQ (0–7) x 10)

Unit: none

Default value: 50




2.1.76 RXLEVOff

Description: This parameter determines the quality level offset of the interface

handover of the AMR FR service relative to non-AMR services or the AMR HR

service (x 10).


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Value range: 0–70 (RQ (0–7) x 10)

Unit: none

Default value: 5

Configuration policy: For the AMR calls, this parameter, together with RXQUALn, is

used in interference handover decision. An uplink interference handover is easily

triggered if this parameter is set to a smaller value.


2.1.77 Intracell HO Allowed

Description: This parameter determines whether the intra-cell handover is enabled.


Unit: none

Default value: No


Relevant algorithm: interference handover algorithm, BQ handover algorithm, AMR

handover algorithm, and no downlink measurement report handover algorithm

2.1.78 Rx_Level_Drop HO Allowed

Description: This parameter determines whether the rapid level drop handover

algorithm is enabled.


Unit: none

Default value: No


Relevant algorithm: rapid level drop handover algorithm

2.1.79 Filter Parameter A1–A8

Description: Filter Parameter A1–A8, together with Filter Parameter B, determines


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whether the rapid drop of the receive level is contained in one or multiple

measurement reports.

Value range: 0–20

Unit: none

Default value: 10

Configuration policy: Filter Parameter A1–A8 must meet the condition: A1 + A2 +

A3 + A4 + A5 + A6 + A7 + A8 = 80. The settings of A1 to A8 reflect the number of

measurement reports in which the receive level drops rapidly.


2.1.80 Filter Parameter B

Description: This is one of the parameters that determine whether a handover is

required due to rapid level drop. This parameter indicates the drop trend of the

receive level within a period.


Unit: none

Default value: 0

Configuration policy: If this parameter is set to a greater value, a more rapid level

drop is required for triggering a rapid level drop handover.


2.1.81 BQ HO Allowed

Description: This parameter determines whether the BQ handover is enabled.


Unit: none

Default value: Yes

Configuration policy: none

Relevant algorithm: BQ handover algorithm


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2.1.82 DLQuaLimitAMRFR

Description: This parameter determines the downlink receive quality threshold for

emergency handover of AMR FR calls.

Value range: 0–70 (RQ (0–7) x 10)

Unit: none

Default value: 65

Configuration policy: The setting of this parameter influences the triggering of BQ

handover of AMR FR calls. If it is set to a small value, the downlink BQ handover is

easily triggered.


2.1.83 ULQuaLimitAMRFR


emergency handover of AMR FR calls.

Value range: 0–70 (RQ (0–7) x 10)

Unit: none

Default value: 65


handover of AMR FR calls. If it is set to a small value, the uplink BQ handover is

easily triggered.


2.1.84 DLQuaLimitAMRHR

Description: This parameter determines the downlink receive quality threshold for

emergency handover of AMR HR calls.

Value range: 0–70 (RQ (0–7) x 10)

Unit: none


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Default value: 60


handover of AMR HR calls. If it is set to a small value, the downlink BQ handover is

easily triggered.


2.1.85 ULQuaLimitAMRHR


emergency handover of AMR HR calls.

Value range: 0–70 (RQ (0–7) x 10)

Unit: none

Default value: 60


handover of AMR HR calls. If it is set to a small value, the uplink BQ handover is

easily triggered.


2.1.86 DL Qual. Threshold

Description: This parameter determines the downlink receive quality threshold for an

emergency handover of non-AMR calls. An emergency handover is triggered when

the downlink receive quality is greater than DL Qual. Threshold.

Value range: 0–70 (RQ (0–7) x 10)

Unit: none

Default value: 60


handover of non-AMR calls. If it is set to a small value, the downlink BQ handover is

easily triggered.



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2.1.87 UL Qual. Threshold

Description: This parameter determines the uplink receive quality threshold for an

emergency handover of non-AMR calls. An emergency handover is triggered when

the uplink receive quality is greater than UL Qual. Threshold.

Value range: 0–70 (RQ (0–7) x 10)

Unit: none

Default value: 60


handover of non-AMR calls. If it is set to a small value, the uplink BQ handover is

easily triggered.


2.1.88 BQ HO Margin

Description: This parameter, together with Inter-cell Handover Hysteresis , filters

the neighbor cells during handover triggered due to bad receive quality.

Value range: 0–127 (–64 dB to +63 dB)

Unit: none

Default value: 69

Configuration policy: The difference between Inter-cell Handover Hysteresis and

BQ HO Margin is used to filter the candidate cells. If the BQ HO Margin is set to a

higher value, the threshold for the candidate cells is lowered, thus a neighbor cell is

more likely to become a target cell for handover.


2.1.89 Load HO Allowed

Description: This parameter determines whether the load handover is allowed for

traffic load balancing.


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Unit: none

Default value: No


Relevant algorithm: load handover algorithm

2.1.90 System Flux Threshold for Load HO

Description: This parameter determines the current system flux threshold, to

determine whether the CPU is overloaded.

Value range: 0–11

Unit: none

Default value: 10

Configuration policy: The value of this parameter should not be set too high. Load

handover is allowed only when the system flow is lower than the setting of this

threshold. Otherwise, the system load is even more burdened.


2.1.91 Load HO Threshold

Description: The traffic load of a cell refers to the TCH seizure rate in the cell. The

load handover is triggered when the traffic load in a cell reaches this threshold. In

other words, the load handover is triggered when the ratio of TCHs occupied in a cell

reaches the threshold defined for load handover.


Unit: %

Default value: 85

Configuration policy: The setting of this parameter influences the triggering of the

load handover. If it is set to a lower value, the number of load handover times

increases.


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2.1.92 Load HO Step Period

Description: When the load of a cell is equal to or greater than Load HO Threshold,

all the call connections served in this cell may send handover requests at the same

time, thereby leading to sudden increase of CPU load. In some cases, call drops may

occur due to traffic congestion in the cell. Therefore, the hierarchical handover

algorithm for load handover is used for the BSC to control the number of users to be

handed over by levels. This parameter determines the period for each load handover

level.


Unit: seconds

Default value: 10

Configuration policy: The setting of this parameter influences the load handover

time. If it is set to a high value, the handover time of each level is long.


2.1.93 Load HO Step Level

Description: In hierarchical load handover, starting from the Edge HO DL RX_LEV

Threshold, the upper limit of the load handover strip increases by one Load HO

Step Level every Load HO Step Period. The handovers are performed as such until

all the calls whose receive levels are within the range of (Edge HO DL RX_LEV

Threshold, Edge HO DL RX_LEV Threshold + Load HO Bandwidth) are handed

off the current serving cell. The value of Load HO Step Level must be smaller than

that of the Load HO Bandwidth.

Value range: 1–63

Unit: dB

Default value: 5


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Configuration policy: The setting of this parameter influences the width of the

handover strip during load handover.


2.1.94 Load HO Bandwidth

Description: A load handover is allowed only when the receive level of the serving

cell is within the range of (Edge HO RX_LEV Threshold, Edge HO RX_LEV

Threshold + Load HO bandwidth).

Value range: 0–63

Unit: dB

Default value: 25

Configuration policy: The setting of this parameter determines the maximum width

of the handover strip during load handover.


2.1.95 Load Req. on Candidate Cell

Description: If the cell load is smaller than the value of this parameter, the cell can

accept load handovers from other cells. Otherwise, the cell rejects load handover

requests from other cells.


Unit: %

Default value: 75

Configuration policy: The setting of this parameter influences the load handover

targeted to the cell. If it is set to a lower value, the number of handover requests that

are rejected increases.



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2.1.96 Edge HO Allowed

Description: This parameter determines whether the edge handover is enabled.


Unit: none

Default value: Yes

Configuration policy: The recommended setting of this parameter is Yes, to enable

the edge handover algorithm.

Relevant algorithm: edge handover algorithm

2.1.97 Edge HO UL RX_LEV Threshold

Description: If the UL receive level remains lower than the Edge HO UL RX_LEV

Threshold for a period, the edge handover is triggered.

Value range: 0–63

Unit: dBm; physical value range: -110 dBm to -47 dBm

Default value: 10

Configuration policy: This parameter should be adjusted as required. If the Edge

HO UL RX_LEV Threshold is set to an excessively small value, call drop may easily

occur. If the PBGT handover is enabled, the relevant edge handover threshold can be

decreased.


2.1.98 Edge HO DL RX_LEV Threshold

Description: If the DL receive level remains lower than the Edge HO DL RX_LEV

Threshold for a period, the edge handover is triggered.

Value range: 0–63

Unit: dBm; physical Value range: -110 dBm to -47 dBm

Default value: 20


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Configuration policy: This parameter should be adjusted as required. If the Edge

HO UL RX_LEV Threshold is set to an excessively small value, call drop may easily

occur. If the PBGT handover is enabled, the relevant edge handover threshold can be

decreased.


2.1.99 Edge HO Watch Time(s)

Description: This parameter determines the intervals when the UL and DL receive

level are measured to determine whether an edge handover should be triggered.

Value range: 1–16

Unit: seconds

Default value: 3

Configuration policy: The larger the parameter value is, the more difficult the edge

handover can be triggered.


2.1.100 Edge HO Valid Time (s)

Description: This parameter determines, in the edge handover statistical time, the

period during which the UL or DL receive level is lower than its corresponding edge

handover threshold.

Value range: 1–16

Unit: seconds

Default value: 2





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2.1.101 NC Edge HO Watch Time(s)


period during which the UL or DL receive level is higher than its corresponding edge

handover threshold.

Value range: 1–16

Unit: seconds

Default value: 3




2.1.102 NC Edge HO Valid Time (s)


period during which the UL or DL receive level is higher than its corresponding edge

handover threshold.

Value range: 1–16

Unit: seconds

Default value: 2




2.1.103 MS Fast Moving HO Allowed

Description: This parameter determines whether an MS that moves fast in a micro

cell can be handed over to a macro cell. If this parameter is set to Yes, the MS that

moves fast in a micro cell can be handed over to a macro cell, thus reducing

handovers.


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Unit: none

Default value: No

Configuration policy: Huawei recommends that this handover be applied only in

special areas such as highways to reduce the CPU load. Fast movement handover is

used only in special conditions.


2.1.104 MS Fast-moving Watch Cells

Description: Suppose that the actual number of the micro cells passed by the

fast-moving MS is P. According to the P/N rule, when the MS fast passes N cells

among the P micro cells, the BSC starts to trigger a fast-moving micro-to-macro cell

handover.

Value range: 1–10

Unit: none

Default value: 3

Configuration policy: The more the micro cells are, the more difficult to trigger the

fast-moving micro-to-macro cell handover is.


2.1.105 MS Fast-moving Valid Cells

Description: Suppose that the actual number of the micro cells passed by the

fast-moving MS is N. According to the P/N rule, when the MS fast passes N cells

among the P micro cells, the BSC starts to trigger a fast-moving micro-to-macro cell

handover.

Value range: 1–10

Unit: none

Default value: 2


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Configuration policy: The more the micro cells are, the more difficult to trigger the

fast-moving micro-to-macro cell handover is.


2.1.106 PBGT HO Allowed

Description: This parameter determines whether the PBGT (POWER BUDGET)

handover algorithm is allowed.


Unit: none

Default value: Yes

Configuration policy: You are advised to enable the PBGT handover algorithm.

Proper use of PBGT handovers helps to reduce inter-cell coverage and to avoid

co-channel interference, intra-frequency interference, and inter-frequency

interference.

Relevant algorithm: PBGT handover algorithm

2.1.107 PBGT HO Threshold

Description: The PBGT handover to an adjacent cell occurs when the difference

between the downlink level of the adjacent cell and that of the serving cell is greater

than PBGT HO Threshold.


Unit: dB (-64 dB to 63 dB)

Default value: 68

Configuration policy: Reducing PBGT HO Threshold makes the PBGT handover

more accessible. If the PBGT HO Threshold is set to an excessively small value,

ping-pong handover may easily occur.



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2.1.108 PBGT Watch Time (s)

Description: This parameter determines the period during which the BSC measures

the path loss of the neighbor cells. Based on the result, the BSC determines whether

to trigger the PBGT handover.

Value range: 1–16

Unit: seconds

Default value: 3

Configuration policy: The larger the parameter value is, the more difficult the PBGT



2.1.109 PBGT Valid Time (s)

Description: This parameter determines the period during which a neighbor cell is

measured and granted as the candidate cell for PBGT handover.

Value range: 1–16

Unit: seconds

Default value: 2

Configuration policy: The larger the parameter value is, the more difficult the PBGT



2.1.110 Intracell F-H HO Allowed

Description: This parameter determines whether AMR handover is allowed. When

the Intracell HO Allowed is set to Yes, this parameter is valid.


Unit: none

Default value: Yes


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Configuration policy: Only when both Intracell HO Allowed and Intracell F-H HO

Allowed are set to Yes, the AMR handover can be triggered.

Relevant algorithm: AMR handover algorithm

2.1.111 Penalty Time after AMR TCHF-H HO Fails(s)

Description: This parameter determines the penalty time for AMR full rate to half rate

(FR-to-HR) handovers. Before the timer expires, no AMR FR-to-HR handover

request is allowed. If the previous full-half handover fails due to channel unavailability

or channel mismatch.


Unit: seconds

Default value: 30

Configuration policy: The greater the value of this parameter is, the longer the

penalty time after AMR TCHF-H HO fails is. That is, triggering AMR handover

becomes more difficult.


2.1.112 F2H HO th

Description: This parameter determines the threshold of the full-rate TCH to half-rate

TCH handover. When an AMR call occupies a full-rate TCH, an intra-cell full-rate

TCH to half-rate TCH handover is triggered if the radio quality indication (RQI)

remains higher than the configured F2H HO threshold for a predefined period.

Value range: 0–39

Unit: dB

Default value: 25

Configuration policy: The greater the value of this parameter is, the more difficult

the AMR full-rate TCH to half-rate TCH handover can be triggered.



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2.1.113 H2F HO th

Description: This parameter determines the threshold of the half-rate TCH to

half-rate TCH handover. When an AMR call occupies a full-rate TCH, an intra-cell

half-rate TCH to full-rate TCH handover is triggered if the radio quality indication (RQI)

remains lower than the configured F2H HO threshold for a predefined period.

Value range: 0–39

Unit: dB

Default value: 10

Configuration policy: The smaller the value of this parameter is, the more difficult

the AMR half-rate TCH to full-rate TCH handover can be triggered.


2.1.114 Intracell F-H HO State Time (s)

Description: This parameter determines the statistical time of the intra-cell full-rate to

half-rate handover decision.

Value range: 1–16

Unit: seconds

Default value: 5

Configuration policy: The larger the parameter value is, the more difficult the AMR



2.1.115 Intracell F-H HO State Time (s)

Description: This parameter determines the lower time threshold for triggering AMR

handover within the AMR handover statistic time. (P/N criterion: Within N seconds,

the conditions are met for at least P seconds. Where, P is the low limit.)

Value range: 1–16


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Unit: seconds

Default value: 2

Configuration policy: The larger the parameter value is, the more difficult the AMR



2.1.116 Outgoing-RAT HO Allowed

Description: This parameter determines whether outgoing-RAT (2G to 3G) handover

and cell reselection are allowed.


Unit: none

Default value: No

Configuration policy: if 3G neighbor cell is configured, outgoing-RAT (2G to 3G)

handover is allowed.

Relevant algorithm: TA handover algorithm, interference handover algorithm, rapid

lever drop algorithm, bad quality handover algorithm, edge handover algorithm, 3G

better cell handover algorithm, and directed retry algorithm

2.1.117 Better 3G Cell HO Allowed

Description: This parameter is used to control the enabling of the better FDD 3G cell

handover algorithm. Yes indicates the configuration is allowed, and No indicates the

configuration is not allowed.


Unit: none

Default value: No

Configuration policy: This parameter must be set to Yes when 2G/3G network is

applied.

Relevant algorithm: 3G better cell handover algorithm


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2.1.118 TDD Better 3G Cell HO Allowed

Description: This parameter is used to control the enabling of the better TDD 3G cell

handover algorithm. Yes indicates the configuration is allowed, and No indicates the

configuration is not allowed.


Unit: none

Default value: No

Configuration policy: This parameter can be set to Yes when 2G/3G network is

applied.


2.1.119 RSCP Threshold for Better 3G CELL HO

Description: This parameter is used to control the 3G better cell handover in FDD

mode. If both Outgoing-RAT HO Allowed and Better 3G Cell HO Allowed are set

to Yes, a better 3G cell handover is triggered when the RSCP of a 3G neighbor cell is

greater than RSCP Threshold for Better 3G Cell HO during a period.

Value range: 0–63

Unit: none

Default value: 50


the 3G better cell handover can be triggered.


2.1.120 TDD RSCP Threshold for Better 3G CELL HO

Description: This parameter is used to control the 3G better cell handover in TDD


to Yes, a better 3G cell handover is triggered when the RSCP of a 3G neighbor cell is


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greater than RSCP Threshold for Better 3G Cell HO during a period.

Value range: 0–63

Unit: none

Default value: 50




2.1.121 Ec/No Threshold for Better 3G CELL HO

Description: This parameter is used to control the 3G better cell handover in FDD


to Yes, a better 3G cell handover is triggered when the Ec/No of a 3G neighbor cell is

greater than Ec/No Threshold for Better 3G Cell HO during a period of time.

Value range: 0–49

Unit: none

Default value: 35




2.1.122 3G Better Cell HO Valid Time

Description: This parameter is used to control handovers in FDD mode. During the

decision of 3G better cell handover algorithm, 3G better cell handover is originated

only when the period that meets the conditions of the 3G better cell handover

algorithm in the measurement period is greater than 3G Better Cell HO Valid Time.

This parameter determines the valid time of the 3G better cell handover algorithm.

Value range: 1–16

Unit: seconds


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Default value: 4

Configuration policy: The larger the parameter value is, the more difficult the 3G

better cell handover can be triggered.


2.1.123 3G Better Cell HO Watch Time

Description: This parameter is used to control handovers in FDD mode. During the





Value range: 1–16

Unit: seconds

Default value: 5

Configuration policy: The larger the parameter value is, the more difficult the 3G

better cell handover can be triggered.


2.1.124 TDD 3G Better Cell HO Valid Time

Description: This parameter is used to control handovers in TDD mode. During the





Value range: 1–16

Unit: seconds

Default value: 4

Configuration policy: The greater the value of this parameter is, the more difficult to


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trigger the 3G better cell handover is.

Relevant algorithm:3G better cell handover algorithm

2.1.125 TDD 3G Better Cell HO Watch Time

Description: This parameter is used to control handovers in TDD mode. During the





Value range: 1–16

Unit: seconds

Default value: 5

Configuration policy: The greater the value of this parameter is, the more difficult to

trigger the 3G better cell handover is.

Relevant algorithm:3G better cell handover algorithm

2.1.126 Inter-RAT HO Preference

Description: This parameter determines whether the MS is preferentially handed

over to a 2G cell or a 3G cell.

Value range: Pre_2G_Cell, Pre_3G_Cell, Pre_2G_CellThres

Unit: none

Default value: Pre_2G_CellThres

Configuration policy: If this parameter is set to Pre_2G_Cell, the BSC selects the

target handover cell from the 2G candidate cells. If this parameter is set to

Pre_3G_Cell, the BSC selects the target handover cell from the 3G candidate cells. If

this parameter is set to Pre_2G_CellThres , and if the receive level of the first

candidate cell among 2G candidate cells is smaller than or equal to the

Pre_2G_CellThres, the 3G cell handover is preferred. Otherwise, the 2G cell


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handover is preferred.




2.1.127 Inter-RAT HO Preference


over to a 2G cell or an FDD 3G cell.


Unit: none












2.1.128 TDD Inter-RAT HO Preference


over to a 2G cell or a TDD 3G cell.


Unit: none



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2.1.129 HO Preference Threshold for 2G Cell

Description: This parameter is used to control the handover between the 2G cell and

the FDD 3G cell. If the Inter-RAT HO Preference is HO Preference Threshold for

2G Cell, and if the receive level of the first candidate cell among 2G candidate cells is

smaller than or equal to the Pre_2G_CellThres, the 3G cell handover is preferred.

Otherwise, the 2G cell handover is preferred.

Value range: 0–63

Unit: none

Default value: 25

Configuration policy: The greater the value of this parameter, the more difficult for

the BSC to hand over the MS to a 2G cell and the easier for the BSC to hand over the

MS to an FDD 3G cell.





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2.1.130 TDD HO Preference Threshold for 2G Cell

Description: This parameter is used to control the handover between the 2G cell and

the TDD 3G cell. If the Inter-RAT HO Preference is HO Preference Threshold for

2G Cell, and if the receive level of the first candidate cell among 2G candidate cells is

smaller than or equal to the Pre_2G_CellThres, the 3G cell handover is preferred.

Otherwise, the 2G cell handover is preferred.

Value range: 0–63

Unit: none

Default value: 25

Configuration policy: The greater the value of this parameter, the more difficult for

the BSC to hand over the MS to a 2G cell and the easier for the BSC to hand over the

MS to a TDD 3G cell.




Handover Algorithm (Complete and Detailed)

Documents

emergency handover

load handover

normal handover

ta handover

interference handover

handover decision algorithms

bad quality handover

railway fast handover