ZGO-02!02!001 Handover Between Macro- And Micro-cells Feature Guide ZXG10 IBSC (V12.3.0)
description
Transcript of ZGO-02!02!001 Handover Between Macro- And Micro-cells Feature Guide ZXG10 IBSC (V12.3.0)
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ZGO-02-02-001 Handover
between Macro- and
Micro-cells
Feature Guide
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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.
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
In configuration resources tree window, double click Configuration Management
Modify Area Handover Control, set parameter Allow Macro-Micro delay handover, as
shown below.
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Figure 6-2 Configuring to Allow Macro-Micro Delay Handover
In configuration resources tree window, double click Configuration Management
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
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In configuration resources tree window, double click Configuration Management
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
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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
In configuration resources tree window, double click Configuration Management
Modify Area Handover Control, set parameter Allow Macro-Micro delay handover as
no, as shown below.
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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).
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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