GSM RNO Subject-3G Neighbor Cell Planning and Configuration at the 2G Side_R1.1

8/10/2019 GSM RNO Subject-3G Neighbor Cell Planning and Configuration at the 2G Side_R1.1

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3G Neighbor Cell Planning and

Configuration at the 2G SideR1.1


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3G Neighbor Cell Planning and Configuration at the 2G Side Internal Use Only

ZTE Confidential Proprietary 2014 ZTE CORPORATION. All rights reserved. I

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ZTE Confidential Proprietary 2014 ZTE CORPORATION. All rights reserved. III

About This Document

Summary

Chapter Description

1 Overview Describes the meaning of the neighbor cell planning and

configuration.2 Configuration of BasicParameters Related to the NeighborCell

Describes the basic parameter configuration of the neighborcell.

3 Principles of Neighbor CellConfiguration

Describes the principles of the neighbor cell configuration.

4 Configuration of InteroperationControl Parameters After theNeighbor Cell Configuration

Describes the interoperation control parameter configurationafter the neighbor cell configuration.

5 Precautions Describes the precautions of the neighbor cell planning andconfiguration.


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ZTE Confidential Proprietary 2014 ZTE CORPORATION. All rights reserved. V

FIGURES

Figure 2-1 Configuration Window of the 2G-3G Interoperation ............................................. 4

Figure 2-2 Configuring the UTRAN External Cell ................................................................. 5

Figure 2-3 Configuring the TDD External Cell ...................................................................... 6

Figure 2-4 Creating the UTRAN External Cell Reselection/Handover................................... 7

Figure 2-5 Configuring Interoperation Parameters................................................................ 7

Figure 4-1 Cell Control Parameters .................................................................................... 10

Figure 4-2 Configuring Handover Parameters 1 ................................................................. 13



Figure 4-5 Configuring Directional Retry Parameters 1 ...................................................... 15

Figure 4-6 Configuring Directional Retry Parameters 2 ...................................................... 15

Figure 4-7 Enabling the Allow Automatic Handover Based on Traffic Option ...................... 16

Figure 4-8 Setting the Threshold of Traffic for Handover .................................................... 16

Figure 4-9 Setting the Threshold of Inter-RAT Traffic Handover Decision .......................... 17

TABLES

Table 2-1 GSM Network Parameters.................................................................................... 2

Table 2-2 GSM Cells ............................................................................................................ 3

Table 2-3 3G Network Parameters ....................................................................................... 3

Table 2-4 TDD Cells ............................................................................................................. 3

Table 2-5 FDD Cells ............................................................................................................. 3


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ZTE Confidential Proprietary 2014 ZTE CORPORATION. All rights reserved. 1

1 Overview

The neighbor cell configuration is the most basic configuration of the 2G-3G

interoperation. The purpose of configuring neighbor cells is to build communication

channels between different networks. On the basis of the above basic condition, the

cellphone can test the designated network or cell by reading the system message and

then it can reside or initiate service at various access sides by performing reselection or

handovers.

The neighbor cell configuration includes the basic cell information configuration and cell

control parameter configuration. The cell control parameter configurations are various for

different interoperation functions. The parameters corresponding to different

interoperation functions are described as follows.


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2 Configuration of Basic Parameters

Related to the Neighbor Cell

2.1 General Principles of Adjacent CellConfiguration

Cell information configuration

The cell information is configured so that the cellphone can identify different cell

signals and the tests of different cells can be performed.

Parameters related to cell control

The UTRAN cell control parameters are configured for the achievement of various

interoperation functions. For example, parameters of the reselection and handover

are different.

Neighbor cell optimization

The neighbor cell optimization method is relatively simple. From the single cell

perspective, there are two methods of neighbor cell optimization. One is adding

neighbor cells and the other is deleting neighbor cells. From the CN perspective,besides the above two methods, the engineers should configure the

single/bidirectional neighbor cells on the basis of the network coverage and capacity

and re-allocate the incoming and outgoing handovers of the neighbor cell according

to different algorithms.

2.2 Preparation of Reselection and HandoverNeighbor Cell Parameters

In order to commission the 2G-3G interoperation, it is necessary for the 2G network

engineers to provide the following parameters of handover and reselection cells to the 3G

network engineers.

Table 2-1 GSM Network Parameters

MCC MNC


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Table 2-2 GSM Cells

Cell CI NCC BCC LAC BCCH Band Indicator

Meanwhile, it is necessary for the 3G network engineers to provide the following

parameters of handover and reselection cells to the 2G network engineers.

Table 2-3 3G Network Parameters

MCC MNC

Table 2-4 TDD Cells

RNCID

CellID

LAC

ARFCN

3G

Scrambling

Code

Diversity

Bandwidth3G

CCN

SUPPORT

CellType3G

SyncCase

TSTD

Table 2-5 FDD Cells

RNCID

CellID

LAC

ARFCN

3G

ScramblingCode

Diversity RACCellType

3G

The above is the basic cell information transferred during the interoperation.

2.3 Configuration Procedure of the UTRAN NeighborCell

Configuration procedure:

1. Configuring the UTRAN external cell

2. Configuring the reselection and handover cell

2.3.1 Configuring the UTRAN External Cell

In the Configuration Resource Tree window, right click OMC> GERAN Subnetwork>

BSC Managed Element> BSC Function> External Cell Config> Create > UTRAN

External Cell, as shown in the following figure.


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Figure 2-1 Configuration Window of the 2G-3G Interoperation

Click UTRAN External Cell, configure the following parameters in the Check UTRAN

External Celldialog box:

User label

External UTRAN ID

UTRAN cell type: FDD/TDD

MCC

MNC

UTRAN cell frequency

LAC

RNC ID

C ID


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Scrambling code or cell parameter

TX diversity indication

RAC

The dialog box is shown in the following figure.

Figure 2-2 Configuring the UTRAN External Cell

For the TDD cell, configure the following parameters:

User label

External UTRAN ID

UTRAN cell type: FDD

MCC

MNC

UTRAN cell frequency

LAC

RNC ID


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C ID

Scrambling code or cell parameter

TX diversity indication

RAC

UTRAN cell band width

TSTD is used

Figure 2-3 Configuring the TDD External Cell

2.3.2 Configuring the GSM UTRAN Reselection and Handover Cell

Create the UTRAN adjacent cell reselection, UTRAN adjacent cell handover, or UTRAN

adjacent cell reselection and handover, as shown in the following figure.


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Figure 2-4 Creating the UTRAN External Cell Reselection/Handover

Create the URTAN adjacent cell reselection, handover, or reselection and handover on

the basis of different interoperation strategies.

Figure 2-5 Configuring Interoperation Parameters


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3 Principles of Neighbor Cell

Configuration

3.1 6.10 Version

The number of neighbor cells for a cell is limited as follows:

The maximum number of 3G neighbor cells is 64 in case only the 3G neighbor cells

are configured.

The maximum number of both 2G and 3G neighbor cells is 64.

3.2 6.20 Version

The number of neighbor cells for a cell is limited as follows:

The maximum number of 3G neighbor cells is 64 in case only the 3G neighbor cells

are configured.

The maximum number of both 2G and 3G neighbor cells is 96.

3.3 Number of Neighbor Cells Based onMeasurement Parameters

There are two measurement methods for the inter-RAT measurement. One is the

measurement report and the other is the enhanced measurement report.

For the measurement report, when the BCCH_FREQ_NCELLparameter is set to 31for

the adjacent cell (the corresponding RXLEV_NECLL parameter refers to the

measurement result (RSCP or Ec/No) of a 3G adjacent cell), the corresponding BSIC is

the location of the 3G adjacent cell in the 3G adjacent cell list. Thus, the maximumnumber of adjacent cells reported by the GSM adjacent cell is reduced from 32 to 31. And

the number of WCDMA neighbor cells is 62.

Four parameters (that is, RXLEV_VAL, MEAN_BEP, CV_BEP, and

NBR_RCVD_BLOCKS) are added to the measurement values about the serving cell in

the ENHANCED MEASUREMENT REPORTmessage. Besides, the GSM adjacent cells

with invalid BSIC (which are not described in the system message but are permitted by

NCC) are in the invalid_BSIC_informationunit. The cells with valid BSIC and the 3G

quality are in the REPORTING_QUANTITIY(in bitmap format) unit. Only when at least

one BSIC is configured in each BCCH in the BA can this message be used. The


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advantage is: If the cellphone is required not to report the cell with invalid BSIC, the

reported maximum 6 adjacent cells will be valid. After the EMR is used, the maximum

number of WCDMA neighbor cells supported by the BSS is increased to 64.

For the configuration of WCDMA neighbor cells, after the EMR is used, the limit

conditions of the iOMCR include:

The maximum number of neighbor cells (including GSM, WCDMA, and TD-SCDMA)

is 96.

The maximum number of WCDMA neighbor cells is 64.

The maximum number of WCDMA neighbor cells with the same frequency is 32.

The maximum number of WCDMA neighbor cell frequencies is 3.

If the WCDMA and TD-SCDMA neighbor cells co-exist, the engineers can control the

priority order between WCDMA and TD-SCDMA by means of the FDDTDDPrio

parameter at the iBSC side.


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4 Configuration of Interoperation Control

Parameters After the Neighbor CellConfiguration

The configurations of interoperation control parameters are various on the basis of

different neighbor cell functions. Besides the basic measurement parameters, the cell

control parameters of the reselection neighbor cell, handover neighbor cell, reselection

and handover neighbor cell are described as follows.

4.1 Configuring Cell Control Parameters

The key parameters are described as follows.

Figure 4-1 Cell Control Parameters

The correlations among key measurement parameters, protocol fields, and iBSC fields

are listed in the following table when the cellphone is in idle and handover status.

Parameter in3GPP Protocols

Descriptionand Default

Value

Value

Range

Parameter onthe iOMCR

Recommended Value

Channel

Qsearch_ISearch for 3Gcells if signallevel is below

0-15Measurementthreshold of UEperforming

7BCCHD/L


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Parameter in3GPP Protocols

Descriptionand Default

Value

Value

Range

Parameter onthe iOMCR

Recommended Value

Channel

6 dB, 2 =18dB, 3 =8 dB,4 =16 dB, 5=10 dB, 6 =

14 dB, 7 =12 dB.

Default value=12 dB.

Qsearch_C

Search for 3Gcells if signallevel belowthreshold

(07):98,94, ,74 dBm,(always)or abovethreshold(815):78,74, ,

54 dBm,(never)

015

Thresholdwhen UEperformssearch underspecializedmode(Qsearch_C)

7SACCH D/L

REPORT_TYPE

Indicateswhich reporttype the MSshall use,0 = enhanced,1 = normal

Default value= normal

0/1

CSmeasurementtype reportedby UE(ReportTypeCS)

BCCHD/L

SACCH D/L

FDD_REP_QUANT

Indicates thereportingquantity forUTRAN FDDcells,0 = RSCP, 1 =Ec/No

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CS class ofreportedquantities ofUTRANadjacent cells(FDDrepQntCS)

BCCHD/L

SACCH D/L

3G_SEARCH_PRIO

Indicates if 3Gcells may besearchedwhen BSICdecoding isrequired,0 = no, 1 =yes

Default value= yes

0/1

CS UE searchUTRANadjacent cell inBSIC decodingframe indication(SearchPrioCS3G)

SACCH D/L


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Among the above parameters, the Qsearch_I, XXX_Qoffset, and FDD_Qmin

parameters are combined to achieve the 2G-to-3G reselection. (In the versions later than

iBSCv6.20.200f (included), the FDD_RSCPminand FDD_Qmin_Offsetparameters are

added and the reselection algorithm is updated.)

4.2 Configuring Handover Decision Parameters

Enable the inter-RAT handover, as shown in Figure 4-2. These three thresholds are

corresponding to the FDD RSCP, FDD Ec/No, and TDD handover decision threshold.

That is to say, if the FDD_REP_QUANTparameter is set to 0(that is, the cellphone of

FDD uses the RSCP value to report the measurement report), the iBSC will use the FDD

RSCP threshold to perform the handover decision. For the TDD, only the TDD RSCP

threshold is used.

Figure 4-2 Configuring Handover Parameters 1

Set the inter-RAT handover priority strategy, as shown in the following figure.



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Set the RSCP and Ec/No offsets, as shown in the following figure.


4.3 Configuring the Inter-RAT Directional Retry

This function is used when the GSM channels are all occupied. The CS service initiated

by a new cellphone will be evenly set up on the adjacent UTRAN cell by means of

directional retry. Therefore, the users perception can be improved.

Enable the Outer redirection enableoption in the Operation Control Parameterstab.


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Figure 4-5 Configuring Directional Retry Parameters 1

And then enable the Directed retry to UTRAN cell allowedoption.

Figure 4-6 Configuring Directional Retry Parameters 2

4.4 Configuring the Inter-RAT Traffic Handover

In the area covered by both the 3G and GSM networks, the engineers can balance or

control the inter-RAT service type and load by means of the inter-RAT handover, so that

the users demanding will be fulfilled, the network will be optimized, and the network

capacity will be expanded.


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Figure 4-9 Setting the Threshold of Inter-RAT Traffic Handover Decision

Only when the loads of the 2G and 3G networks are extremely unbalanced (for example,

the 2G users are few but the 3G users are many) is the inter-RAT load balance algorithm

used. If only the load of the 3G network is unbalanced, the engineers can make full use of

other means of the 3G network to make adjustments. It is not recommended to perform

the load handover to affect the stable 2G network.


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5 Precautions

The following conditions should be checked and prevented.

5.1 TDD A + B Scheme

Some TDD cellphones crash due to the cellphone defects in the decoding system

message of SI 2QUATERand measurement information. In order to avoid this condition,

the engineers should modify the system message of SI 2QUATER and measurement

information, which is called A + B scheme. The engineers should disable the TDD cell

handover enableoption to use the A + B scheme. When the engineers merely modify

this option, they should unblock all the cells and the system message will be generatedagain.

5.2 Prohibiting Configuring the 3G Neighbor Cell tothe 3G Handover and Reselection Cell

During the interoperation with the WCDMA network, because some cellphones like

cloned cellphones and Samsung cellphones have defects, they fail to decode the

measurement information sent by the SACCH in special mode. Thus, the black screen

will happen and the call will automatically restart or drop during the conversion.

The engineers should configure the reselection neighbor cell instead of the handover

neighbor cell to avoid the problem.

5.3 Reselection in Idle Status (Configuring BCCHsInstead of SCs)

Currently, only the BCCH is configured for the reselection in idle status. The SC is not

configured. Only the cellphones with Qualcomm chips can perform the reselection. Nokia

cellphones cannot perform the reselection. This function is under developing.

5.4 Number of Neighbor Cells

The number of neighbor cells should meet the actual requirement. The engineers should

not configure too many neighbor cells.


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5.5 Minimum Number of AGCH Reserved BlocksBeing 2

Make sure that the number of AGCH reserved blocks should no less than 2, so as toavoid the condition that the cellphones of some models do not read the SI2QUATER

message in the Um interface system messages.

If the problem happens, the engineers should observe the messages in the SIB3 and

check whether this message indicates that the sending location of the SI2QUATER

message is BCCH ext. The solutions to this problem are simple. One is to set the

number of AGCH reserved blocks. The other is to set the sending location of the

SI2QUATER message. Set the SI2quaterPos parameter to 1, so that the 2QUATER

message is broadcast on the expanded BCCH.

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GSM RNO Subject-3G Neighbor Cell Planning and Configuration at the 2G Side_R1.1

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