zgo-02!02!001 handover between macro- and micro-cells feature guide zxg10 ibsc (v12.3.0)

ZGO-02-02-001 Handover

between Macro- and

Micro-cells

Feature Guide

ZGO-02-02-001 Handover between Macro- and Micro-cells

ZTE Confidential Proprietary 1

ZGO-02-02-001 Handover between Macro- and

Micro-cells

Version Date Author Reviewer Notes

V1.0 2013/10/28

Xia Jun,

Zhu

Hongbo

Gu Yuhui New

2014 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 in this document is subjected to

change without notice.


2 ZTE Confidential Proprietary

TABLE OF CONTENTS

1 Feature Attribute ............................................................................................... 4

2 Overview ............................................................................................................ 4

2.1 Feature Introduction ............................................................................................. 4

2.2 License Control .................................................................................................... 5

2.3 Correlation with Other Features ........................................................................... 5

3 Technical Description ....................................................................................... 6

4 Parameters and Configurations ....................................................................... 7

4.1 Parameter List ..................................................................................................... 7

4.2 Parameter Configuration ...................................................................................... 8

4.2.1 Neighboring cell layer .......................................................................................... 8

4.2.2 Allow Macro-Micro delay handover ...................................................................... 9

4.2.3 Macro to micro handover Threshold ..................................................................... 9

4.2.4 Macro to micro handover value N ...................................................................... 10

4.2.5 Handover from macro to micro ........................................................................... 10

5 Related Counters and Alarms ........................................................................ 11

5.1 Related Counters ............................................................................................... 11

5.2 Related Alarms .................................................................................................. 11

6 Engineering Guide .......................................................................................... 11

6.1 Application Scenario .......................................................................................... 11

6.2 Feature Commissioning ..................................................................................... 12

6.3 Feature Validation .............................................................................................. 14

6.3.1 Macro to Micro handover ................................................................................... 14

6.4 Feature Turn off ................................................................................................. 15

6.5 Network Impact .................................................................................................. 16

7 Abbreviation .................................................................................................... 17

8 Reference Document ....................................................................................... 17



FIGURES

Figure 6-1 Configuring Neighboring Cell Layer ..................................................................12

Figure 6-2 Configuring to Allow Macro-Micro Delay Handover ...........................................13

Figure 6-3 Configuring Macro to Micro Handover Threshold/Value N ................................13

Figure 6-4 Handover from macro to micro ..........................................................................14

Figure 6-5 Allow Macro-Micro delay handover ...................................................................16

TABLES

Table 4-1 Parameter List .................................................................................................... 7

Table 4-2 Configuration rule of Neighboring cell layer ......................................................... 8

Table 4-3 Configuration rule of allow macro-micro delay handover ..................................... 9

Table 4-4 Configuration rule of macro to micro handover threshold .................................... 9

Table 4-5 Configuration rule of macro to micro handover value N ......................................10

Table 4-6 Configuration rule of macro to micro handover start threshold ...........................10

Table 5-1 Counters list .......................................................................................................11



1 Feature Attribute

BSC Version: [ZXG10 iBSC V6.30.103]

BTS Version: [Not related with BTS hardware platform]

Property: [Optional]

Related Network Element:

NE Name Related or Not Special Requirements

MS - BTS -

BSC

MSC Intra-BSC handover is not involved, but

inter-BSC handover is involved.

MGW -

SGSN -

GGSN -

HLR -

Dependent Function: [None]

Exclusive Function: [None]

Note: [None]

2 Overview

2.1 Feature Introduction

This feature enables the handover algorithm from the macro-cell to the micro-cell

(Macro-micro handover) and from the micro-cell to the macro-cell (Micro-macro

handover), which are mainly applied in the multi-layer network.

Macro-cell and micro-cell is a logical concept, which is not the macro and micro cellular



cell. For example, 900M/1800M cell is set as the macro-cell and the micro-cell, and

900M/1800M cell is also be set as the macro-cell and the micro-cell. That is, any two

cells are set suitable relationship according to the requirement from the spot.

ZTE GSM supports macro-micro handover. When the downlink level of the serving cell is

equal or lower than the initial threshold, the handover decision of macro-micro handover

is started. BSC judges if the slow moving terminal handover to the lower layer of the

serving cell, which is the neighboring cell. The triggering condition of macro-micro

handover is: the neighboring cells level is greater than the threshold for N times.

Macro-micro handover balances the traffic between the macro-cell and the micro-cell. As

a result, the signaling load decreases, and the service efficiency is improved.

Usually, Power BudGeT (PBGT) handover has higher priority than macro-micro

handover. With a view to the variety of the handover algorithms in the actual situation,

sometimes the terminals should be handed over to the absorbing traffic layer as soon as

possible, which is macro-micro handover. Sometimes the terminals should stay at the

primary layer, which is PBGT handover, so the priority of PBGT handover and

macro-micro cell handover is adjusted on OMCR.

ZTE GSM also supports the handover from the micro-cell to the macro-cell, which is

realized through the handover based on uplink level fast fading. When the uplink level of

the terminal fast fading to the threshold for N times continuously, BSC select the related

cell (configured at OMCR) first as the target cell to execute handover, improving the

handover speed so as to reduce the call drop risk of the level fast fading..

2.2 License Control

None license control for this feature in UR12 Release.

2.3 Correlation with Other Features

This feature relates to the following features:

ZGO-05-02-008 Multi-layer Cell Structure



Relation with Multi-layer Cell Structure: Handover from macro- to micro-cell in this

feature, only the lower-layer cells can be selected as the target cell; If no related cell

exists, the selection is made in the rule of upper layer-same layer-lower layer

3 Technical Description

The handover from macro-cell to micro-cell is mainly applied in a dual-layer network.

That is, the slowly moving MS handover from the macro-cell to the micro-cell. A

judgement for the slowly moving MS is made as whether the MS is allowed handover to

a cell at a layer lower than the current cell. Therefore, the layer of neighbour cell should

be lower than that of serving cell (NCellLayer=Lower).

First, avRxLevel of downlink measure report is bigger than byMacroMicroStartThs,then

can trigger Macro- to Micro-cell handover.

The triggering condition of handover from macro-cell to micro-cell is: The level of

neighbour cell exceeds the threshold value for continuous N times (See parameter

configuration: MacroMicroHoN).

The handover decision is made by formula below.

HoThsMacroMicro n)AvRxLevel( (1)

In formula (1), AvRxLevel(n) refers to the average level of a specific neighbor cell,

MacroMicroHoThs is the threshold for handover from macro-cell to micro-cell. If

continuous N number of AvRxLevel satisfy formula (1), the neighbor cell is recorded as

candidate cell for handover from macro- to micro-cell. Traverse the neighbor cell list, if

candidate cell number is bigger than 0, the handover from macro- to micro-cell is

executed.

If candidate cell number is bigger than 1, the candidate cells should be sequenced by

three factors: priority, traffic and radio state. Among which priority and traffic takes

preference. The flowchart is shown as below



Ms in 900M cell,receive meas

report

Start

Ms in cell1.BSC receive measure

report

abyRxLevel=MacroMicroHoThs

Ms now in cell2

End

4 Parameters and Configurations

4.1 Parameter List

Table 4-1 Parameter List

SN Name Figure

1 hoControlMacroMicro Figure 6-2

2 MacroMicroHoThs Figure 6-3

3 MacroMicroHoN Figure 6-3

4 NCellLayer Figure 6-1



5 macroMicroStartThs Figure 6-4

4.2 Parameter Configuration

4.2.1 Neighboring cell layer

Table 4-2 Configuration rule of Neighboring cell layer

Full name Neighboring cell layer

Abbreviation NCellLayer

Description

This parameter provides the handover policies in multilayer

network technology and dual-frequency network technology.

Multilayer radio coverage can be formed in the same physical

area.

The PBGT handover defined in the specifications at one layer can

reduce the number of handovers during the call, thus improving

the system reliability and communication quality. The policy of

handover between a macro cell layer and a micro cell layer mainly

depends on the moving speed of MS. An MS at higher moving

speed will try to stay at the macro cell layer (upper layer of the

micro cell layer), and an MS at lower moving

speed will try to enter the micro cell layer (lower layer of the macro

cell layer). Only in the case of PBGT handover and emergency,

will the undefined cell of the service area be considered as a

candidate cell.

Same layer of the home cell: Adjacent cell and local cell are in the

same layer (PBGT handover possible); Upper layer of the home

cell: Adjacent cell is the upper layer of local cell (local cell is a

micro cell); Lower layer of the home cell: Adjacent cell is the lower

layer of local cell (local cell is a macro cell).

Managed object Adjacent GSM Cell Configuration

Value range

0: Undefined

1: Same layer of the home cell

2: Upper layer of the home cell

3: Lower layer of the home cell

Unit N/A



Default value 1

4.2.2 Allow Macro-Micro delay handover

Table 4-3 Configuration rule of allow macro-micro delay handover

Full name Allow Macro-Micro delay handover

Abbreviation hoControlMacroMicro

Description This parameter determines whether to allow Macro-Micro delay

handover.

Managed object Handover Control

Value range 0: No

1: Yes

Unit N/A

Default value 0

4.2.3 Macro to micro handover Threshold

Table 4-4 Configuration rule of macro to micro handover threshold

Full name Macro to micro handover Threshold

Abbreviation macroMicroHoThs

Description

During macro-micro handover, some parameters shall be used.

That is, a signal strength threshold and a counter value.

Macro-micro handover threshold is a value of signal intensity

threshold. If the measured signal intensity of an adjacent micro cell

is higher than MacroMicroHoThs (threshold value) for certain

times, then it triggers handover to the adjacent micro-cell.

In this way, it could move slow moving MS into micro cell layer.

The times can be determined by MacroMicroHoN parameter in

each adjacent cell. The setting of parameter "MacroMicroHoN" in

the local micro cell is related to the local cell size and the standard

used in measuring the MS moving speed.

Managed object PS Handover Control

Value range 063

Unit N/A



Default value 20

4.2.4 Macro to micro handover value N

Table 4-5 Configuration rule of macro to micro handover value N

Full name Macro to micro handover value N

Abbreviation macroMicroHoN

Description

During macro-micro handover, some parameters shall be used.

That is, a signal strength threshold and a counter value.

Macro-micro handover threshold is a value of signal intensity

threshold. If the measured signal intensity of an adjacent micro cell

is higher than MacroMicroHoThs (threshold value) for certain

times, then it triggers handover to the adjacent micro-cell.

In this way, it could move slow moving MS into micro cell layer.

The times can be determined by MacroMicroHoN parameter in

each adjacent cell. The setting of parameter "MacroMicroHoN" in

the local micro cell is related to the local cell size and the standard

used in measuring the MS moving speed.

Managed object PS Handover Control

Value range 1255

Unit N/A

Default value 2

4.2.5 Handover from macro to micro

Table 4-6 Configuration rule of macro to micro handover start threshold

Full name Handover from macro to micro

Abbreviation macroMicroStartThs

Description Current cell downlink average level is not bigger than

threshold,macrotomicro handover can be triggered.

Managed object Handover Control



Value range 063

Unit N/A

Default value 63

5 Related Counters and Alarms

5.1 Related Counters

Table 5-1 Counters list

Counter ID Name

C901060013 Number of SDCCH handover attempts due to macro-micro switch

C901060036 Number of TCH/F handover attempts due to macro-micro switch

C901060059 Number of TCH/H handover attempts due to macro-micro switch

C901130030 Handover attempts due to other causes of the full rate second sub

cell

C901130044 Handover attempts due to other causes of the half rate second sub

cell

5.2 Related Alarms

This feature has no related alarms.

6 Engineering Guide

6.1 Application Scenario

The macro- to micro-cell handover is usually applied for dual-layer network, whose

common networking mode is: 900M cell as serving cell, 1800M cell as lower layer cell,

and other 900M cells as the same layer cells. By macro- to micro-cell handover, traffic in



900M cell is able to hand over to 1800M cell; by PBGT handover, traffic in 900M cell can

transfer to other 900M cells.

6.2 Feature Commissioning

In configuration resources tree window, double click Configuration Management

Modify Area Adjacent Relation ConfigurationAdjacent GSM Cell Configuration, set

parameter Neighboring cell layer, as shown below.

Figure 6-1 Configuring Neighboring Cell Layer


Modify Area Handover Control, set parameter Allow Macro-Micro delay handover, as

shown below.



Figure 6-2 Configuring to Allow Macro-Micro Delay Handover


Modify Area Adjacent GSM Cell Configuration, set parameter Macro to micro

handover threshold and Macro to micro handover Value N, as shown below.

Figure 6-3 Configuring Macro to Micro Handover Threshold/Value N




Modify Area Handover Control, set parameter Handover from macro to micro, as

shown below.

Figure 6-4 Handover from macro to micro

6.3 Feature Validation

6.3.1 Macro to Micro handover

Test Item Macro to Micro handover

Precondition 1. Check CN is healthy.

2. Check BSC is healthy.

3. Check SDR is healthy.

4. Check default cell configuration and parameters in

BSC.

5. MSs are ready.

6. Ensure good radio environment.

Test Steps 1. Configure cell A as macro cell, cell B as micro cell.

2. Configure cell B as adjacent cell of cell A and lower

layer.

3. Set the parameter hoControlMacroMicro of cell A as



YES.

4. Set the parameters of cell A MacroMicroHoThs=25 and

MacroMicroHoN=8.

5. Make a call in cell A using MS.

6. If the continuous number of the RxLevel of cell B higher

than -85dBm is more than 8 times, the MS will be

triggered to handover to cell B.

Anticipative Result 1. In step 6, the handover will be successful and the call is

normal.

2. In step 6, the handover completed signaling can be

found in Abis interface.

3. In step 6, the handover performed signaling can be

found in A interface, the cause of handover is Better

cell.

Test Result 1. Macro to micro handover performed successfully

Parameters Setting Refer to test steps

6.4 Feature Turn off


Modify Area Handover Control, set parameter Allow Macro-Micro delay handover as

no, as shown below.



Figure 6-5 Allow Macro-Micro delay handover

6.5 Network Impact

Impact on Network

The macro-cell to micro-cell handover is enabled to achieve balanced traffic, ease

network congestion, improve network quality and enhance users perception.

But it also brings negative impacts:

Increases handovers

If parameter HoMarginPbgt is set too low, frequent handover may be caused.

If parameter MacroMicroHoThs is set too high, the traffic loading effect is not obvious; if

set it too low, the frequent handover appears, user s signal is weakened or signals

fluctuation is complained and KPI of lower layer cell (such as call drop rate and

congestion) becomes worse.

If PBGT handover parameter PbgtHoLayer is not set as Allow PBGT handover to lower

layer neighboring cell, the PBGT handover to lower layer neighboring cell fails (set by

parameter NCellLayer).



Thus, the above parameters should be set appropriately as per the actual conditions.

Impact on NE

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

7 Abbreviation Abbreviations Full Characteristics

3GPP 3rd Generation Partnership Project

GSM Global System for Mobile communications

BSC Base Station Controller

BTS Base Transceiver Station

MS Mobile Station

MSC Mobile Switching Centre

AMR Adaptive Multi-Rate

FR Full Rate

HR Half Rate

SDCCH Stand alone dedicated Control Channel

OMC Operation and Maintenance Center

SACCH Slow Associated Control Channel

TCH Traffic Channel

TDMA Time Division Multiplex Access

8 Reference Document

ZXG10 iBSC GSM (V6.30.103) Performance Counter Reference

ZXG10 iBSC GSM (V6.30.103) Radio Parameter Reference

1 Feature Attribute2 Overview2.1 Feature Introduction2.2 License Control2.3 Correlation with Other Features

3 Technical Description4 Parameters and Configurations4.1 Parameter List4.2 Parameter Configuration4.2.1 Neighboring cell layer4.2.2 Allow Macro-Micro delay handover4.2.3 Macro to micro handover Threshold4.2.4 Macro to micro handover value N4.2.5 Handover from macro to micro

5 Related Counters and Alarms5.1 Related Counters5.2 Related Alarms

6 Engineering Guide6.1 Application Scenario6.2 Feature Commissioning6.3 Feature Validation6.3.1 Macro to Micro handover

6.4 Feature Turn off6.5 Network Impact

7 Abbreviation8 Reference Document

zgo-02!02!001 handover between macro- and micro-cells feature guide zxg10 ibsc (v12.3.0)

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