6 gsm neighboring cell optimization principles, tools, and deliverables 20101130

HUAWEI TECHNOLOGIES CO., LTD.

www.huawei.com

Huawei Confidential

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英文标题 :40-47pt 副标题 :26-30pt字体颜色 : 反白内部使用字体 :

FrutigerNext LT Medium外部使用字体 : Arial

中文标题 :35-47pt字体 : 黑体

副标题 :24-28pt字体颜色 : 反白

字体 : 细黑体 Prepared by: Zeng ShujingReviewed by: Qi Haofeng

GSM Neighboring Cell Optimization: Principles, Tools, and Deliverables

July 30, 2010

Abstract

This slide describes the principles and tools of GSM

neighboring cell optimization. Neighboring cell optimization is

intended to avoid missing and redundant neighboring cells,

which improves the GSM network performance.

HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential

R&D SupportHuawei provides training in and around-the-clock technical support for neighboring cell optimization.

R&D support personnel

Name Employee ID PhoneCui Xiaoyi 51635 See the phone book.

Zeng Shujing 134972 See the phone book.


Change HistoryDate Version Description Reviewed by Prepared by

2010-07-30 July Completed the draft. Qi Haofeng Zeng Shujing

2010-11-30 December

1. Added KPIs to be checked after neighboring cell optimization.2. Added the disabling of redundant neighboring cells based on the geographical positions and handover parameters.

Peng Xiang, Liu Zhihua, Cui Xiaoyi, He Xiaomei, Chen Wei, Liu Xiuyu, Jiang Ying, Yan Yafeng, Liang Jian, Zhao Jinjin, Qi Haofeng, Gao Shuliang, Guo Hongliang, Ni Hongxiang, Zhu Kan, Chen Ruiqun, Chen Kai, Li Wenhui, Zhang Zhenhua, Li Peng, Ma Jing

Zeng Shujing


Neighboring Cell Optimization Schemes: Principles and Tools

Neighboring Cell Optimization Schemes　 Missing Neighboring Cell Optimization Redundant Neighboring Cell Optimization 　

A new Nastar platform is deployed onsite.

Requirement Scheme Advantage and Disadvantage

1. NastarV600R002 and later versions 2. BSC6000 V900R008C01 and later versions 3. M2000 V200R008C01SPC010 and later versions

The new Nastar platform automatically outputs suggestions on neighboring cell optimization according to MR data.

Advantage: Based on the actual traffic interference situation of the existing network, the output suggestions is accurate and reliable. Disadvantage: The NE mapping version is restricted.

Disable redundant neighboring cells based on the MR data and Outgoing Handover Measurement and Incoming Handover Measurement under GSM cell - GSM cell.

No new Nastar platform is deployed onsite.

Early stage of frequency replanning

Old Nastar platform

1. Manually check all cells to determine whether missing neighboring cells exist; 2. Output suggestions on neighboring cell planning according to location relation to detect missing neighboring cells.

Advantage: An old Nastar platform is stand-alone and thus is easy to install. The software is available at http://support.huawei.com and can be used with a license applied for from http://w3.huawei.com/dominoapp/isc/license/bulletin.nsfDisadvantage: Only longitudes and latitudes are considered. Therefore, the old Nastar platform is not as accurate and reliable as the new one.

Disable redundant neighboring cells base on Outgoing Handover Measurement and Incoming Handover Measurement under GSM cell - GSM cell.

U_Net license

Conduct emulation prediction according to input RF parameters, antenna heights, azimuths, and tilts, and plan neighbor relation of each cell. In this way, missing neighboring cells are detected.

Advantage: Suggestions on neighboring cell planning can be conveniently output through emulation. Disadvantages: 1. It is hard to obtain the license of the U_Net onsite because the license must be purchased.2. It is hard to control the planning results that rely on the accuracy of engineering parameters.

Drive test tool

Determine whether missing neighboring cells exist according to abnormal events during DT tests.

Advantage: Missing neighboring cells can be accurately and reliably detected according to call situations. Disadvantage: Only routing situations can be indicated.

1. Cellopt license2. BSC6000 V900R008C01 and later versions The Cellopt automatically

outputs suggestions on neighboring cell optimization according to MR data.

Advantage: 1.Based on the actual traffic interference situation of the existing network, the output suggestions are accurate and reliable. 2. The frequency replanning center outputs suggestions on neighboring cell optimization and frequency schemes at the same time to reduce onsite workload. Disadvantage: 1. As software for frequency replanning, the Cellopt is used only at sites where frequency replanning is conducted because its license is expensive. 2. MR data needs to be transmitted to the frequency replanning center onsite. The center then outputs optimization suggestions. Large amount of MR data leads to interworking troubles.

Late stage of frequency replanning

1. Cellopt license2. BSC6000 V900R008C01 and later versions

http://support.huawei.com/


Optimizing Neighboring CellsObjectives:

To disable redundant neighboring cells: Disable redundant neighboring cells to improve handover rate.

Reserve the space of the BA2 table to collect MR data.

To add missing neighboring cells: Reduce the interference between neighboring cells during frequency replanning.

Improve the handover success rate.

Reduce the call drop rate.

Application scenarios: Neighboring cell optimization after network adjustment: The neighboring cell

relations change because of the addition, migration, and capacity expansion of the

cells.

Periodically neighboring cell optimization on the entire network: For network

adjustment because of changes to the network scale and subscriber distribution,

you need to check and optimize neighboring cells periodically on the entire

network.

Neighboring cell optimization in certain areas: Centrally perform neighboring cell

optimization for the cell clusters or VIP areas with low KPI performance.


Optimizing Neighboring CellsMethod for optimizing redundant neighboring cells:Perform the optimization based on the following KPIs:

H370c:CELLCELL_OUTCELL_HO_REQ

H380:CELLCELL_INCELL_HO_REQ

H375B: CELLCELL_OUT_CELL_HO_FAIL_RECONN_FAIL_TIMES

Methods for optimizing missing neighboring cells: Perform the optimization based on MR data, including the following KPIs:

S371:CELL_NCELL_SCELL_LEV_GT_RTHRES_MR_NUM

S372:CELL_NCELL_LEV_GT_ABS_THRES_MR_NUM

S3013:CELL_SCELL_MR_NUM

Perform neighboring cell optimization based on topology structures.

Perform neighboring cell optimization based on drive tests.


Optimizing Redundant Neighboring Cells Based on Hanover MeasurementCollect handover measurement data under GSM cell –GSM cell for one week and check the data

as follows:

1. If the sum of H370c:CELLCELL_OUTCELL_HO_REQ and

H380:CELLCELL_INCELL_HO_REQ is smaller than 10, the related neighboring cell may be

redundant.

2. If the ratio of H375B: CELLCELL_OUT_CELL_HO_FAIL_RECONN_FAIL_TIMES to

H370c:CELLCELL_OUTCELL_HO_REQ is greater than 10%, the related neighboring cell may

be redundant.

3. Determine the redundant neighboring cell based on geographical position. If the neighboring

cell is far from the serving cell, or the neighboring cell is near the serving cell but the azimuths of

the two cells are opposite to each other, you need to disable the redundant neighboring cell.

Otherwise, you need to check whether the handover parameters are set properly.


Optimizing Missing Neighboring Cells Based on MR Data

Basic principles:

On the existing network, handover has two requirements for the neighboring cell level:

Neighboring cell level - Serving cell level > Relative level threshold 68 (the actual value is 68 – 64 = 4 dB)

Neighboring cell level > Absolute level threshold 30 (the actual value is 30 – 110 = –80 dBm)

Principles

Algorithm principles: The integrated priority is calculated as follows: (S371 x 50% + S372 x 50%)/S3013.

Rank neighboring cells in the descending order of integrated priorities. The vertical coordinate indicates the integrated

priority; the horizontal coordinate indicates the rank of neighboring cells.

Set the threshold of the vertical coordinate TH, and thresholds of the horizontal coordinate NO.1 and NO.2 to divide

neighboring cells to three areas. Process neighboring cells in the three areas as follows:

Light-green area: Neighboring cells in this area are non-defined and

considered as missing neighboring cells.

Rose-pink area: Neighboring cells in this area are defined and

considered as redundant neighboring cells.

Other areas: Neighboring cells in other area are not processed.


Optimizing Missing Neighboring Cells Based on MR DataThe KPIs required in the neighboring cell optimization and those required in the frequency

replanning are all under Neighbor Cell Level Measurement per Cell. The software parameter

configurations and NE restriction related to the data collection are the same as that in the

frequency replanning.

1. Cellopt

Click all KPIs under Neighbor Cell Level Measurement per Cell during frequency

replanning. The Cellopt can read required KPIs based on the input original MR data (in the .mrf

form) and output suggestions for neighboring cell optimization.

2. New Nastar platform

For details about the operation procedure see the 《 Guide to Optimizing GSM Neighboring

Cells and Frequencies Through Nastar 》 .


Optimizing Missing Neighboring Cells Based on Topology StructuresStand-alone Nastar1. Start the stand-alone Nastar and choose Neighboring Analysis > Auto Neighboring Planning. Compare the

exported result of neighboring cell planning with the actual neighboring cell relations configured on the existing

network and add the missing neighboring cells.


Optimizing Missing Neighboring Cells Based on Topology StructuresOld Nastar platform

2. Choose Neighboring Analysis > Neighboring Display. Check all neighboring cells. Add the neighboring cell whose

azimuth faces the azimuth of the serving cell or neighboring cells close to the serving cell as missing neighboring cells.

The azimuth of the neighboring cell

(SJGH0489_0) faces that of the

serving cell SJGH0371_0. Add

SJGH0489_0 as the missing

neighboring cell.


Optimizing Missing Neighboring Cells Based on Coverage PredicationU_Net emulationStart the U_Net and perform the coverage predication. Then, choose Transmitter > Neighbors > Automatic

Allocation. Compare the exported result of neighboring cell planning with the actual neighboring cell

relations configured on the existing network and add the missing neighboring cells.


Optimizing Missing Neighboring Cells Based on Drive TestsOptimize missing neighboring cells based on call situations.

The results of drive tests show that call drop occurs because the level decreases. The neighboring cell level is

higher than the serving cell level by more than 10 dB, but handover does not occur. The serving cell SJGH0244_2

does not configure SJGH0354_0 as its neighboring cell. Call drop occurs due to the missing neighboring cell.


KPIs Assessed After Neighboring Cell Optimization1. Click Outgoing Handover Measurement and Outgoing Handover Measurement

under GSM Cell to GSM Cell. Check the following KPIs of the pair of the serving cell

and the added missing neighboring cell: H370c:CELLCELL_OUTCELL_HO_REQ,

H380:CELLCELL_INCELL_HO_REQ, and

RH373:CELLCELL_OUTCELL_HO_SUCC_RATE. If there are many occurrences of

H370c:CELLCELL_OUTCELL_HO_REQ and H380:CELLCELL_INCELL_HO_REQ,

and CELL_HO_SUCC_RATE is high, you can determine the missing neighboring cell.

2. Check ZTR304: CELL_RATE_TCH_CALL_DROP_INCLUDE_HO and CELL_HO_SUCC_RATE in the area of neighboring cell optimization. If the KPIs increase or fluctuate, the neighboring cell optimization is proper; if the KPIs decrease evidently, the missing neighboring cells are added or redundant neighboring cells are disabled improperly.

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6 gsm neighboring cell optimization principles, tools, and deliverables 20101130

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