117366585-ZGF05-02-001-Basic-Handover

ZGF05-02-001 Basic Handover

Feature Description



Version Date Author Approved By Remarks

V8.1.1 2009-03-04 Not open to the Third Party



V8.1.4 2010-01-26Not open to the Third Party，add pingpong handover penalty strategy

ZTE Confidential Proprietary © 2008 ZTE Corporation. All rights reserved. I

© 2010 ZTE Corporation. All rights reserved.

ZTE CONFIDENTIAL: This document contains proprietary information of ZTE and is not to be disclosed or used without the prior written permission of ZTE.

Due to update and improvement of ZTE products and technologies, information of the document is subjected to change without notice.


TABLE OF CONTENTS

1 Feature Attribute.......................................................................................................................1

2 Overview12.1 Correlation with Other Features...............................................................................................2

3 Technical Description...............................................................................................................33.1 Handover Parameter Configuration..........................................................................................33.2 Measurement Report Processing.............................................................................................43.3 Handover Decision...................................................................................................................53.4 Target Cell Selection................................................................................................................73.5 Target Cell Sequencing............................................................................................................93.6 Handover Failure Penalty Strategy........................................................................................10

4 Parameters and Configuration...............................................................................................104.1 Parameter List........................................................................................................................104.2 Parameter Configuration........................................................................................................14

5 Related Counters and Alarms................................................................................................165.1 Related Counters...................................................................................................................165.2 Related Alarms.......................................................................................................................17

6 Engineering Guide..................................................................................................................176.1 Application Scenario..............................................................................................................176.2 Configuration Description.......................................................................................................176.3 Network Impacts....................................................................................................................17

7 Abbreviation............................................................................................................................18

8 Reference Document..............................................................................................................18

FIGURES

II © 2008 ZTE Corporation. All rights reserved. ZTE ConfidentialProprietary


Handover Flow..............................................................................................................................3

BSC Function Radio Basic Pproperty Configuration Interface...............................................14

Handover Condition Configuration Interface............................................................................14

Adjacent cell handover and reselection configuration interface............................................15

15

Handover Condition Configuration Interface............................................................................15

TABLES

List of parameters in Power Budget Equations..........................................................................5

Algorithm priority range of various handover algorithm...........................................................6

Description of handover decision related parameters..............................................................7

Target cell selection strategies for various handover algorithm..............................................8

ZTE Confidential Proprietary © 2008 ZTE Corporation. All rights reserved. III


1 Feature AttributeiBSC version: [ZXG10 iBSC V6.20]

BTS version: [No requirement for the BTS software/hardware platform ]

Attribute: [Basic function]

NEs involved:

NE Name Involved or Not Special Requirement

MS -

BTS -

BSC √

MSC √Intra-BSC handover is not involved, but inter-BSC handover is involved.

MGW -

SGSN -

GGSN -

HLR -

Dependency: [None]

Mutual exclusion: [None]

Note: [None]

2 OverviewIn most cases, the mobile phone (MS) constantly sends measurement report to BSC during conversation. BSC determines whether to perform handover or not based on the report, in this procedure, it updates the list of candidate handover cells and then performs handover based on the list.

Handover includes the following types:

• Intra-cell handover: refers to handover between channels of the same type in the same cell.

• Intra-BSC inter-cell handover: refers to handover between channels of the same type in different cells controlled by the same BSC.

• Intra-MSC inter-BSC handover: refers to handover between channels of the same type in different cells controlled by different BSCs under the same MSC.

ZTE Confidential Proprietary © 2008 ZTE Corporation. All rights reserved. 1

Save & average

Target cell sequencing

Failure penalty　 Strategy

Precedence sequencing


• Inter-MSC handover: refers to handover between channels of the same type in different cells controlled by different MSCs.

ZXG10 activates various handover algorithms based on actual network conditions. If all handover algorithms are activated, they will be employed in a certain sequence. Some handover parameters are set in the cell level, the others are set based on adjacent cell.

2.1 Correlation with Other Features

This feature is functionally related with the following features:

• ZGF05-02-002 Basic Handover Decision Criteria

• ZGF05-02-003 Handover Mode

• ZGF05-02-007 Handover between Macro- and Micro-cells

• ZGF05-02-008 Dynamic Handover Priority Algorithm

• ZGF05-02-009 Directed-Shift Handover

• ZGF05-02-013 Handover Failure Penalty

• ZGF05-02-014 Rapid Level Drop Handover

• ZGF05-02-015 Traffic Based Handover

• ZGF05-05-001 Multi-layer Cell Structure

• ZGF05-05-002 Concentric Circle Technology

• ZGF05-09-006 Co-BCCH

Specific description:

1 Relation with Basic Handover Decision Criteria: This feature gives a basic classification for all these basic handover algorithms.Relation with Handover Mode: This feature gives a supplementary description of Handover Mode.

2 Relation with Handover between Macro- and Micro-cells, Directed-shift Handover, Rapid Level Drop Handover, and Traffic Based Handover: This feature gives a basic classification for all these handover algorithms.Relation with Dynamic Priority: The target cell sequencing of this feature adopts the method of Dynamic Priority. Target cell sequencing has two modes: based on priority or based on power budget margin.Priority is classified into static and dynamic priorities.Perform sequencing based on priority of target cells is the first choice, or power budget margin sequencing is triggered when two cells have identical priority.Relation with Failure Penalty: For the details of failure penalty, refer to Handover Failure Penalty.

2 © 2008 ZTE Corporation. All rights reserved. ZTE ConfidentialProprietary

Save & average



Precedence sequencing


3 Relation with Multi-layer Cell Structure: Both cell layer configuration and target cell selection in this feature involves the concept of Layer.

4 Relation with Concentric Circle Technology and Co-BCCH: The intra-cell handover in this feature contains sub-cell handover. Detailed description refers to Concentric Circle Technology and Co-BCCH.

3 Technical DescriptionFigure 1 shows handover flow, including handover parameter configuration, measurement report processing, handover decision, target cell selection, target cell sequencing, failure penalty and handover implementation. Handover implementation is not described here.

Figure 1 Handover Flow

3.1 Handover Parameter Configuration

All the cells can be divided into four layers in present network planning, including umbrella layer, macro-cell layer, micro-cell layer and pico-cell layer. For details of cell layer settings, refer to ZGF05-05-001 Multi-layer Cell Structure.


Start

Handover parameter configuration

Handover decision according to handover threshold

Save & average Measurement report

processing

Handover decision

Target cell selection



Handover arithmetic precedence

Arrangement selection strategy

Handover decision rule

Precedence sequencing PBGT sequencing

Handover implementation End


For parameter configurations of handover algorithms, refer to specific feature of each algorithm, ZGF05-02-002 Basic Handover Decision Criteria, ZGF05-02-007 Handover between Macro- and Micro-cells, ZGF05-02-009 Directed-Shift Handover, ZGF05-02-014 Rapid Level Drop Handover, ZGF05-02-015 Traffic Based Handover, ZGF05-05-002 Concentric Circle Technology and ZGF05-09-006 Co-BCCH.

3.2 Measurement Report Processing

Measurement report is the raw data used to make handover decision. ZTE GSM adopts slide window and weighted average mechanisms to process measurement report.

To avoid unfavorable impact caused by abrupt change in measurement value as a result of complicated radio transmission environment, the average value of measurement data is used to make handover decision, which is known as slide window mechanism. The slide window mechanism discards the oldest data in the last averaging period in the presence of new data, and adds the latest data to retain the same number of data values used for averaging process at all time. The slide window size refers to the number of data values in the slide window. The averaging process only commences when the number of accumulated data values reach the slide window size.

Weighted average is adopted because the system may adopt Discontinuous Transmission (DTX) for both uplink and downlink directions. DTX refers to a process in which the system does not transmit signals during periods of silence when an MS has ongoing conversation. In Continuous Transmission mode, the user can take an average value of measurement results on all timeslots, so the data accuracy is better in this mode. In Discontinuous Transmission mode, the user can take an average value of measurement results on partial timeslots, so the data reliability is low in this mode. Weighted average is to assign a weight larger than one to the data with high reliability in the averaging process.

Measurement report processing features the following:

1 The number of measurement reports must reach the size of slide window, which is 4 by default, before measurement reports are pre-processed.

2 If DTX is enabled, the accuracy of level and quality values in the measurement report is lowered. Therefore, the weight of measurement report in DTX mode differs from that of measurement report in non-DTX mode. The weight of measurement report is constantly 1 when DTX is enabled, and that of measurement report can be set to 1, 2 or 3 (2 by default) when DTX is not enabled.

3 Loss of a maximum ZeroAllowed measurement report(s) is allowed. If over ZeroAllowed measurement report(s) are lost, no calculation is performed in this round, and the slide window starts to collect measurement reports for next round. The measurement value of a lost measurement report is deemed as 0 (that is, -110dBm), but this value is not counted in the averaging process, for example,

If the (K–1)th measurement report is lost and average window size is 8, then

77)-L(KRXLEV_NCEL...2)-L(KRXLEV_NCELL(K)RXLEV_NCELueAverageVal +++=

4 Current power reported in the measurement report is used for subsequent PBGT calculation.



If downlink data is valid in this measurement period and the average value of downlink level is available, the power budge value PBGT of adjacent cell is given by Equation (1) and (2):

Pa PWR_C_D] L[AvRxLev_D-ell(n)AvRxLev_NCPBGT(n) ++= (1)

ity(n))MS_Capabilwr_Max(n),Min(MS_TxP-ity)MS_Capabilwr_Max,Min(MS_TxPPa

BS_TxPwr-Max BS_TxPwr_PWR_C_D

==

(2)

Table 1 describes parameters in Equations (1) and (2)

Table 1 List of parameters in Power Budget Equations

Parameter Description

AvRxLev_NCell (n) Average value of downlink level of adjacent cell received by MS

AvRxLev_DL Average value of downlink level of MS in serving cell.

BS_TxPwr_Max Maximum BTS power in serving cell.

BS_TxPwr Actual BTS power in serving cell.

MS_TxPwr_Max Maximum power of MS in serving cell.

MS_TxPwr_Max(n) Maximum power of MS in adjacent cell.

MS_Capability Power capability of MS in serving cell.

MS_Capability (n) Power capability of MS in adjacent cell.

3.3 Handover Decision

BSC sequentially judges whether one of handover conditions is met and performs handover once one handover condition is met. Generally intra-cell handover algorithm has higher priority than inter-cell handover algorithm.

Intra-cell handover algorithms contain:

• Sub-cell handover.

• Uplink/Downlink interference handover.

Inter-cell handover algorithms contain:

• Uplink/Downlink quality handover.

• Uplink/Downlink level handover.

• MS-BS ultra-long-haul handover.

• Rapid level drop handover.

• PBGT handover.



• Handover between Macro- and Micro-cells.

• Directed-Shift handover.

• Traffic-based handover (BSC-initiated).

• Request handover (MSC-initiated)

• Directional retry.

The above handover algorithm priorities are listed in Table 2.

Table 2 Algorithm priority range of various handover algorithm

Algorithm Priority

Handover Algorithm Handover Type

1 Sub-cell handover Intra-cell handover

2 Uplink/Downlink interference handover Intra-cell handover

3 Uplink/Downlink quality handover Inter-cell handover

4 Uplink/Downlink level handover Inter-cell handover

5 MS-BS ultra-long-haul handover Inter-cell handover

6 Rapid level drop handover Inter-cell handover

7 PBGT handover Inter-cell handover

8 Handover between Macro- and Micro-cells Inter-cell handover

9 Directed-Shift handover Inter-cell handover

Note:

The Algorithm Priority of 1 means the highest priority，the algorithm priority of 2 means the second highest one, and so on. That is to say, when two handover algorithms with different priority are used and met the handover criteria at the same time, the higher priority handover algorithm will be triggered. Intra-cell handover can happen more easily than inter-cell handover, which is up to the practical cases.

Traffic-based handover and requesting handover are respectively initiated by BSC and MSC. Implemented when a call requests channel allocation, directional retry has a handover initiation time and procedure different from those of above handover algorithms.

Except uplink/downlink quality and level handover algorithms which are switched on all the time, other handover algorithms can be enabled or disabled as required through switch settings.

For the relationship between power control and handover, power control should be implemented first through setting appropriate parameters, because power control is faster and better than handover. Handover is easy to result in calling failure and affects the users’ perception. If the conditions of handover and power control are met at the same time, power control and handover will happen at the same time.



3.4 Target Cell Selection

The target cell selection happens after meeting a certain handover algorithm condition.

3.4.1 Intra-cell Handover

Intra-cell handover only requires the change of carrier and timeslot instead of serving cell. Select a carrier first. If there is only one carrier select the timeslot with the lowest interference band as the target timeslot for handover. If the interference bands are the same, select any timeslot to perform handover.

Intra-cell handover also includes inter-cell handover. For details, refer to ZGF05-05-002 Concentric Circle Technology and ZGF05-09-006 Co-BCCH.

Intra-cell handover should be satisfied with Rule 1 of handover decision rules, which is detailed described in section 3.4.2.

3.4.2 Inter-cell Handover

Before selecting target cells for inter-cell handover, BSS should compare the current time point with the last handover success time point first. If the time difference is more than the pingpong penalty time (see parameter configuration: HoBackPenalty), which is set at the last handover success time point, the normal process continues; or the source cell of the last handover will be deleted from the target cells of this handover, then the normal process continues.

When selecting target cells for inter-cell handover, the user needs to take into account cell layer selection strategy and handover decision rules.

For details of layer selection strategy, refer to ZGF05-05-001 Multi-layer Cell Structure.

Handover decision rules are listed as follows:

Rule 1: AvRxLevNCell(n) > RXLEV_MIN(n) + MAX(0,(MS_TXPWR_MAX(n)- P(n))

Rule 2: PBGT(n) > HO_MARGIN(n)

Rule 3: AvRxLevNCell(n) > avRxLevDL + HO_MARGIN_LEVEL(n)

Rule 4: AvRxLevNCell(n) > avRxLevDL + HO_MARGIN_QUAL(n)

The parameters mentioned in the above rules are listed in Table 3.

Table 3 Description of handover decision related parameters

ParameterConfiguration Parameter

Description

RXLEV_MIN(N) RxLevMin Minimum receive level required for handover to the adjacent cell

PBGT(N) / Power budget of the adjacent cell

HO_MARGIN(N) HoMarginPbgt Power budget threshold for handover



to the adjacent cell

HO_MARGIN_QUAL(N) HoMarginRxQual

Quality level threshold for handover to the adjacent cell

HO_MARGIN_LEVEL(N) HoMarginRxLev Level threshold for handover to the adjacent cell

MS_TXPWR_MAX(n) MsTxPwrMax Maximum power of MS in the adjacent cell

P (n) / Power capability of MS in the adjacent cell

avRxLevDL / Average BCCH downlink level of current MS

AvRxLevNcell (N) / Average BCCH downlink level of the adjacent cell

The user can select a target cell according to different combinations of rules 1 to 4. Rule 1 is a mandatory condition, that is, the average level of the adjacent cell for handover must be larger than the minimum handover level. All the handover algorithms must be satisfied with Rule 1.

The target cell selection strategies for various handover algorithms, considering layer selection strategy and handover decision rules, are listed in Table 4.

Table 4 Target cell selection strategies for various handover algorithm

Handover cause Layer selection strategy Handover decision rule

Sub-cell handover Pico timer is invalid. Rule 1

Uplink/Downlink interference handover

Pico timer is invalid. Rule 1

Uplink/Downlink quality handover

If pico timer is working, select a cell in the sequence of upper layer–same layer–lower layer; If it is out of time, select a cell in the sequence of same layer-upper layer-lower layer.

Rules 1&4

Uplink/Downlink level handover


Rules 1&3

MS-BS urtra-long-haul handover


Rule 1



Handover cause Layer selection strategy Handover decision rule

Rapid level drop handover

Pico timer is invalid. Preferentially select a related cell; if there is no such a related cell, select a cell in the sequence of upper layer–same layer–lower layer.

Rule 1

PBGT handover

Select a cell based on the parameter PbgtHoLayer. At the same time, if pico timer is working, no select the cell at the same layer; if it is out of time, preferentially select a cell at the same layer cell.

Rules 1&2

Handover between Macro- and Micro-cells

If pico timer is working, handover is not allowed; if it is out of time, only select a cell at the lower layer.

Rule 1

Directed-shift handover Pico timer is invalid. Rule 1

Traffic based handover Pico timer is invalid. Rule 1

Request handover


Rule 1

Directional retry


Rule 1

Note:

The pico timer is set during handover initialization that will be performed after MS access upon immediate assignment, MS access upon assignment and MS access upon handover. For different handover algorithms, the effect of the pico timer is different.

After finding the proper adjacent cells, sequence these target cells and finally select the optimal one.

3.5 Target Cell Sequencing

Target cell sequencing is determined by three factors: priority, traffic, and radio condition; where the former two impose a principal impact on target cell sequencing. If several target cells have the same priority and traffic, they shall be sequenced based on radio conditions.



Priority is classified into static and dynamic priorities.

Static priority is used to define 8 levels from level 0 to 7 for all the cells. The higher is the level, the higher is the priority of cells. Set different static priority (See parameter configuration: Hopriority) for various target cells based on network traffic and handover success ratio. System will preferentially handover calls to the target cell with the highest static priority.

Dynamic priority is calculated with static priority and the traffic load of target cells. For details of dynamic priorities, refer to ZGF05-02-008 Dynamic Handover Priority Algorithm.

The rules for adjacent cell sequencing are as follows:

1 First, sequence cells based on their priorities. If cells are set with dynamic priorities, sequence cells based on their dynamic priorities; otherwise, sequence cells based on their static priorities.

2 If two cells have the same priority, sequence each of them based on their respective power budget , that is PBGT(n) which is detailed described in section 3.2.

Note: Traffic has been taken into account both in the static and dynamic priorities.

When several target cells have the same priority, sequence them based on their power budget margins.

3.6 Handover Failure Penalty Strategy

Penalty strategies for handover failure can effectively avoid repetitive failures and improve handover success ratio. For more details, refer to ZGF05-02-013 Handover Failure Penalty.

4 Parameters and Configuration

4.1 Parameter List

Related parameters of this feature are described in the table below. Full name Inter-Cell handover allowed Abbreviation InHoEnable

Description

According to GSM specifications, intra-BSC intercell handover is implemented by the following methods: BSC controlled inter-cell handover without MSC involvement. MSC controlled inter-cell intra-BSC handover whose handover flow is similar to that of inter-BSC handover. This parameter decides the choice of method for inter-cell intra-BSC handover. Do select ‘No’ for this parameter if it is not necessary.

ManagementObject

BSC

Value Range Yes/No



Unit None

Default Yes

Full name MIN interval between inter-cell handoverAbbreviation HoMinInterval

Description

This parameter specifies the interval value for which MS waits before the actual inter-cell handover occurs. Such a timer is more predominant for MS at the boundary regions between two cells, where inter-cell handovers occurfrequently. This parameter helps restrict frequentinter-cell handover and guarantees call quality. Inter-cell handover takes place when the timer exceeds the defined interval value from the last inter-cell handover of MS. This parameter affects only the inter-cell handover, but not common intracell or inter-cell concentric handover. In addition, micro-cell has its own handover policy, so this parameter is only effective for macro-cell layer and its above layer. For macro-cell, the default value can be 5; for micro-cell, the default value can only be 0.

ManagementObject Cell

Value Range 0 ~31

Unit s

Default 5

Full name Static Priority of handover

Abbreviation Hopriority

Description

According to GSM specifications, cell priority should be considered in sequencing candidate cells. Therefore, there are three decisive factors to sequence the candidate cells: priority, traffic, and radio conditions. Priority and traffic affect the cell sequencing most. If they lead to the same result, sequence the cells according to the radio conditions. The larger the value, the higher level of priority.


Value Range 0 ~ 7

Unit None

Default 3

Full name MS Max. TxPwr

Abbreviation MsTxPwrMax

Description

In the communication between MS and BTS, the transmission power is controlled by the network. The network sets the power of MS by power

command, which is transmitted on SACCH (SACCH carries the power command with 2-header bytes information, one is power control byte and the other one is timing advance byte). MS sets the specified output transmission power according to the power control header extracted from the SACCH. MS uses the nearest possible output power even if the power command sends maximum output power. When BSC controls the power, the parameter is the maximum transmission power that can be used by MS in the cell. MS max power level is also a parameter used by BSC to calculate PBGT value.

ManagementObject

Cell



Value Range

MAX power level of MS can be divided into four kinds: FR, HR, AMR FR, and AMR HR.

Value range is 0 ~ 31.

Unit None

DefaultIt can be divided into four kinds: FR, HR, AMR FR, and AMR HR. Default value is 0, 5, 0, 0.

Full name MIN power level for handover access

Abbreviation RxLevMin

Description

This parameter defines the minimum receiving intensity level (on BCCH) required for MS to handover to this cell. It is one of parameters to decide preferred cells during handover control. MS in the serving cell constantly monitors the signal intensity on BCCH of adjacent cells. Adjacent cells with the minimum receiving intensity level higher than this parameter are potential candidates for handover. MS with receiving level larger than minimum receiving level indicates that MS is at the edge of the serving cell. It is advised to set this parameter to approximate MS receiving sensitivity. For some cells with traffic overload, increase the minimum access level to decrease C1 and C2 value of the cell, the cell coverage range decreases at the same time. Setting the minimum access level too large will cause crossover area of cells to become dead area. With this measure for traffic balance, it is suggested that the level value should not exceed -90dB. At the preliminary running stage of the network, this parameter can be usually set as 10 (that is, -101 dBm ~ -100 dBm) or lower, which is higher than the MS receiving sensitivity –102 dBm. However, when the network capacity is expanded or the radio coverage in a cell is not a problem, this parameter of the cell can be increased by 2 (dB).

ManagementObject

Cell

Value Range

0 ~ 630: < -110 dBm;1: -110 dBm ~ -109 dBm;2: -109 dBm ~ -108 dBm;……62: -49 dBm ~ -48 dBm;

63: > -48 dBm

Unit None

Default 15

Full name MIN threshold of signal level for handover on PBGT

Abbreviation HoMarginPbgt

Description

According to GSM specifications, handover decisions depend upon received average value of uplink and downlink signal strength. The PBGT value of an adjacent cell is also one of the causes for handover. The decision process is as follows: If the PBGT value of an adjacent cell is greater than the relevant threshold of this cell, handover shall be performed to find a more suitable cell. This parameter defines the threshold used to determine PBGT handover from an adjacent cell to local cell.

ManagementObject

Cell

Value Range 0 ~ 48

0: -24 dB;

1: -23 dB;

……



48: 24 dB

Unit None

Default 30

Full name Minimal Threshold of RxQual HO

Abbreviation HoMarginRxQual

Description

According to GSM specifications, handover decisions depend upon received average value of uplink and downlink signal strength. In handover caused by the quality, adjacent cells should be screened and sequenced. This parameter defines the signal quality threshold to determine handover from adjacent cell to local cell.

ManagementObject

Cell

Value Range

0 ~ 480: -24 dB;1: -23 dB;……

48: 24 dB

Unit None

Default 30

Full name Minimal Threshold of RxLev HO

Abbreviation HoMarginRxLev

Description

According to GSM specifications, handover decisions depend upon received average value of uplink and downlink signal strength. In handover caused by the level, adjacent cells should be screened and sequenced. This parameter defines the signal strength threshold to determine handover from adjacent cell to local cell.

ManagementObject

Cell

Value Range

0 ~ 480: -24 dB;1: -23 dB;……

48: 24 dB

Unit None

Default 30

Full name MIN interval between inter-cell handover

Abbreviation HoBackPenalty

Description

The purpose of it is to avoid the ping-pong handover. For example, one user triggers the handover from cell A to cell B, the user can not handover back to the cell A from cell B during the timer period until it is out of time.


Value Range 0 ~60

Unit s

Default 5



4.2 Parameter Configuration

Figure 2 BSC Function Radio Basic Pproperty Configuration Interface

Figure 3 Handover Condition Configuration Interface



Figure 4 Adjacent cell handover and reselection configuration interface

Figure 5 Handover Condition Configuration Interface



5 Related Counters and Alarms

5.1 Related Counters

Counter ID What It Counts

C900060093 Number of BSC-controlled inter-cell outgoing handover

C900060094 Number of BSC-controlled inter-cell outgoing handover success

C900060095 Number of MSC-controlled outgoing handover

C900060096 Number of MSC-controlled outgoing handover success

C900060097 Number of BSC-controlled inter-cell incoming handover

C900060098 Number of BSC-controlled inter-cell incoming handover success

C900060099 Number of MSC-controlled incoming handover

C900060102 Number of MSC-controlled incoming handover success

C900060119 Number of Intra-cell handover

C900060120 Number of Intra-cell handover success

C901090001 Number of BSC-controlled inter-cell outgoing handover attempts

C901090004 Number of MSC-controlled outgoing handover attempts

C901090011 Number of BSC-controlled inter-cell incoming handover attempts

C901090024 Number of MSC-controlled incoming handover attempts

C901090105 Number of intra-cell handover attempts

C901090148 Number of intra-cell invalid handovers

C901100001 Number of handover attempts on the adjacent cell

C901100002This counter counts the number of success of handover from the selected cell to the adjacent cell

C901100003 Number of handover attempts from adjacent cell to the selected cell

C901100004This counter counts the number of successful handover from the adjacent cell to the selected cell

C901230001 Number of intra-cell handover in attempts

C901230002 Number of intra-cell handover ins success

C901230003 Number of Intra-BSC inter-cell handover in attempts



Counter ID What It Counts

C901230004 Number of Intra-BSC intra-cell handover ins success

C901230005 Number of Intra-MSC inter-cell handover in attempts

C901230006 Number of Intra-MSC inter-cell handover ins success

5.2 Related Alarms

None.

6 Engineering Guide

6.1 Application Scenario

This feature is applicable to the scenarios where handover is activated.

When an MS with ongoing conversation leaves the coverage area of a BTS to that of another, or the call quality decreases due to the interference, the MS needs to hand over from the original voice channel to a new idle one. Handover types vary with the BTSs where the target cell is located.

If the source and target cells are the same cell, initiate an intra-cell handover; otherwise, initiate an inter-cell handover.

The uplink/downlink level quality and TA value measured by MS and BTS are used as fundamental measurement data by the system to decide whether to perform handover and to which cell the MS is to be handed over based on the handover decision algorithm and the resource allocation algorithm.

6.2 Configuration Description

This feature does not involve the adjustment of the iBSC and BTS hardware.

6.3 Network Impacts

6.3.1 Impacts on the network

This feature enables MS to continue their calls when moving around among different cells, and improves network quality and user experience.

Pay attention to the following issues when using this feature:

− Handover candidated cells can be effectively controlled through setting of adjacent cell layer and static priorities.The dynamic priority can help



automatically adjust the traffic distribution in networks and relieve network congestion.

− The handover failure penalty strategy can lessen handover failures to the same target cell, and improve the handover success ratio.

− Layer is a concept regarding logical layers but irrelevant to the type of actual site (macro site and micro site). Layer setting affects the selection priority of target cells during handover. Layer priority is higher than static or dynamic priority.

6.3.2 Impacts on NEs

This feature does not affect the capacity of the iBSC and BTS.

7 AbbreviationAbbreviations Full Characteristics

BSC Base Station ControllerBTS Base Transceiver StationMS Mobile StationPBGT Power Budget

8 Reference Document[1] ZXG10 iBSC (V6.20.10) Performance Counter Manual V1.0

[2] ZXG10 BSS (V6.20.10) Radio Parameters Reference V1.0

[3] ZGF05-02-002 Basic Handover Decision Criteria

[4]ZGF05-02-003 Handover Mode

[5] ZGF05-02-007 Handover between Macro- and Micro-cells

[6] ZGF05-02-008 Dynamic Handover Priority Algorithm

[7] ZGF05-02-009 Directed-Shift Handover

[8] ZGF05-02-013 Handover Failure Penalty

[9] ZGF05-02-014 Rapid Level Drop Handover

[10] ZGF05-02-015 Traffic Based Handover

[11] ZGF05-05-001 Multi-layer Cell Structure

[12] ZGF05-05-002 Concentric Circle Technology

[13] ZGF05-09-006 Co-BCCH




Documents

117366585-ZGF05-02-001-Basic-Handover