2g3g interoperability

GSM BSS

2G/3G Interoperability Feature Parameter Description

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Issue 01 (2010-06-30) Huawei Proprietary and Confidential Copyright © Huawei Technologies Co., Ltd. i

GSM BSS 2G/3G Interoperability Contents

Issue 01 (2010-06-30) Huawei Proprietary and Confidential Copyright © Huawei Technologies Co., Ltd.

ii

Contents 1 Introduction ................................................................................................................................1-1

1.1 Scope ............................................................................................................................................ 1-1 1.2 Intended Audience ........................................................................................................................ 1-1 1.3 Change History.............................................................................................................................. 1-1

2 Overview .....................................................................................................................................2-1

3 Measurement of Neighboring UMTS Cells.........................................................................3-1

4 Common Measurements and Information Exchange Based on Iur-g ........................4-1 4.1 Introduction to Iur-g Interface ........................................................................................................ 4-1 4.2 Common Measurement................................................................................................................. 4-2 4.3 Information Exchange ................................................................................................................... 4-3

5 2G/3G Inter-RAT Cell Reselection ........................................................................................5-1 5.1 Inter-RAT Cell Reselection from UMTS to GSM ........................................................................... 5-1 5.2 Inter-RAT Cell Reselection from GSM to UMTS ........................................................................... 5-1 5.3 Fast 3G Reselection at 2G CS Call Release ................................................................................ 5-2 5.4 NACC and NC2............................................................................................................................. 5-4

6 2G/3G Inter-RAT Handover .....................................................................................................6-1 6.1 Inter-RAT Handover from UMTS to GSM...................................................................................... 6-1 6.2 Inter-RAT Handover from GSM to UMTS...................................................................................... 6-1 6.3 2G/3G Service Distribution and Load Balancing in Access State ................................................. 6-2 6.4 Inter-RAT Load-based Handover in Connect State....................................................................... 6-3

7 Engineering Guidelines...........................................................................................................7-1

8 Parameters .................................................................................................................................8-1

9 Counters......................................................................................................................................9-1

10 Glossary ..................................................................................................................................10-1

11 Reference Documents .........................................................................................................11-1

GSM BSS 2G/3G Interoperability 1 Introduction


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1 Introduction 1.1 Scope This document describes the 2G/3G interoperability feature of Huawei GBSS. It covers the functions of and technologies related to this feature, including measurement of neighboring 3G cells, inter-RAT cell reselection, and inter-RAT handover.

The feature involved is GBFD-114301 GSM / WCDMA Interoperability.

1.2 Intended Audience It is assumed that users of this document are familiar with GSM basics and have a working knowledge of GSM telecommunication.

This document is intended for:

Personnel working on Huawei GSM products or systems System operators who need a general understanding of this feature

1.3 Change History The change history provides information on the changes made to the 2G/3G Interoperability feature in different document versions.

There are two types of changes, which are defined as follows:

Feature change Feature change refers to the change in the 2G/3G Interoperability feature of a specific product version.

Editorial change Editorial change refers to the change in wording or the addition of the information that was not described in the earlier version.

Document Issues The document issues are as follows:

01 (2010-06-30) Draft (2010-03-30)

01 (2010-6-30) This is the first release of GBSS12.0.

Compared with issue Draft (2010-03-30) of GBSS12.0, issue 01 (2010-06-30) of GBSS12.0 incorporates the changes described in the following table.

Change Type Change Description Parameter Change

Feature change None. None.

Editorial change

Parameters are presented in the form of Parameter ID instead of Parameter Name.

None.

GSM BSS 2G/3G Interoperability 1 Introduction


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Draft (2010-03-30) This is the draft release of GBSS12.0.

GSM BSS 2G/3G Interoperability 2 Overview


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2 Overview The UMTS network and the GSM network will coexist and provide services together for a long time. Therefore, 2G/3G interoperability is introduced into the BSS. The 2G/3G interoperability involves inter-RAT handover and inter-RAT cell reselection between GSM and UMTS.

Through 2G/3G interoperability, a smooth evolution from GSM to UMTS can be achieved, thus reducing the CAPEX of operators. For the operator that has both the UMTS network and the GSM network, 2G/3G interoperability can be performed to make the GSM network and the UMTS network work as a supplement to each other, thus expanding the network coverage and improving the service quality. For example, when a dual-mode MS moves to an area without UMTS coverage, it can reselect or be handed over to a GSM cell through 2G/3G interoperability. This improves the user experience.

For the areas covered by both the GSM network and the UMTS network, 2G/3G interoperability can be performed to achieve traffic balance between the GSM and the UMTS. For example, when the traffic load on a GSM cell is too high, 2G/3G interoperability can be performed to switch some calls in the GSM cell to a UMTS cell.

With 2G/3G interoperability, the access policy for the GSM network can be different from that for the UMTS network in the areas covered by both the GSM network and the UMTS network. For example, the GSM network can be preferentially selected by CS services and similarly the UMTS network by PS services. In this way, the advantages of both networks can be achieved.

All the MSs involved in this feature refer to dual-mode MSs.

GSM BSS 2G/3G Interoperability 3 Measurement of Neighboring UMTS Cells


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3 Measurement of Neighboring UMTS Cells The system information contains the neighboring UMTS cell list and UMTS cell reselection parameters, based on which the MS measures the neighboring cell information and performs cell reselection and handover. The system information refers to System Information 2ter, System Information 2Quater, and Measurement Information. System Information 2ter and System Information 2Quater are sent on the BCCH, and Measurement Information is sent on the SACCH. The parameter Send2QuterFlag controls whether System Information 2Quater should be sent.

The MSs in a GSM cell measure the information of both neighboring GSM cells and neighboring UMTS cells. To reduce unnecessary measurements and save power consumption of MSs, the BSS controls the neighboring cell measurement of MSs through parameters. The MSs in idle mode or packet transfer mode can perform inter-RAT cell reselection. The MSs in dedicated mode can perform inter-RAT handover. Operators can set measurement parameters to different values for the MSs in different states.

The MSs in idle mode determine whether to measure the information of neighboring UMTS cells according to QI and the receive level of the serving cell. The conditions for triggering the measurement differ with the value of QI.

If the value of QI ranges from 0 to 6, the measurement is triggered when the receive level of the serving cell is lower than the value of QI.

If the value of QI ranges from 8 to 14, the measurement is triggered when the receive level of the serving cell is higher than the value of QI.

If the value of QI is 7, the MSs always measure the neighboring UMTS cell information regardless of the receive level of the serving cell.

If the value of QI is 15, the MSs never measure the neighboring UMTS cell information regardless of the receive level of the serving cell.

The MSs in packet transfer mode determine whether to measure the information of neighboring UMTS cells according to QP and the receive level of the serving cell. The conditions for triggering the measurement differ with the value of QP.

If the value of QP ranges from 0 to 6, the measurement is triggered when the receive level of the serving cell is lower than the value of QP.

If the value of QP ranges from 8 to 14, the measurement is triggered when the receive level of the serving cell is higher than the value of QP.

If the value of QP is 7, the MSs always measure the neighboring UMTS cell information regardless of the receive level of the serving cell.

If the value of QP is 15, the MSs never measure the neighboring UMTS cell information regardless of the receive level of the serving cell.

The MSs in dedicated mode determine whether to measure the information of neighboring UMTS cells according to QSEARCHC and the receive level of the serving cell. The conditions for triggering the measurement differ with the value of QSEARCHC.

If the value of QSEARCHC is between 0 and 6, the measurement is triggered when the receive level of the serving cell is lower than the value of QSEARCHC.

If the value of QSEARCHC is between 8 and 14, the measurement is triggered when the receive level of the serving cell is higher than the value of QSEARCHC.

If the value of QSEARCHC is 7, the MSs always measure the neighboring UMTS cell information regardless of the receive level of the serving cell.

If the value of QSEARCHC is 15, the MSs never measure the neighboring UMTS cell information regardless of the receive level of the serving cell.

GSM BSS 2G/3G Interoperability 3 Measurement of Neighboring UMTS Cells


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QSEARCHC is contained in the Measurement Information. After entering the dedicated mode, MSs try to obtain the QSEARCHC from the Measurement Information transmitted on the SACCH. Before QSEARCHC is obtained, MSs take the value of QCI that is transmitted on the BCCH as the value of QSEARCHC.

GSM BSS 2G/3G Interoperability

4 Common Measurements and Information Exchange Based on Iur-g


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4 Common Measurements and Information Exchange Based on Iur-g 4.1 Introduction to Iur-g Interface The load information exchanged between 2G and 3G networks is carried in the information elements (IEs) of the handover procedures over the A and Iu interfaces. In this case, unnecessary handover attempts cannot be avoided.

With the development of 3GPP specifications, the Iur-g interface between the RNC and the BSC is used to achieve common measurement and information exchange between 2G and 3G networks. This simplifies the 2G/3G interoperability procedures, reduces the delay caused by handovers, and improves the handover success rate.

Figure 4-1 shows the position of the Iur-g interface in the network architecture.

Figure 4-1 Position of the Iur-g interface in the network architecture

CN

A/Gb Iu

Iur-g

BSC RNC

Iu

Iur

RNC

Figure 4-2 shows the protocol stack defined in 3GPP specifications for the Iur-g interface.




4-2

Figure 4-2 Protocol stack defined for the Iur-g interface

Layer

Transport NetworkControl Plane

Radio Network

Layer

Transport Layer

RNSAP

Transport Network User Plane

Control Plane

MTP3-B

SCCP

M3UAM3UA

SSCF-NNI SCTPSCTP

SSCOPIP

IP

AAL5

DATA LINKATM

Physical

Note that the Iur-g interface has the control plane but does not have the user plane. The Iur-g interface uses IP transmission.

4.2 Common Measurement The common measurement is based on the Iur-g interface. The procedures of the common measurement are performed through connection-oriented signaling. If SPTCOMMMEAS is set to Yes, the common measurement is enabled.

The source BSC/RNC sends a COMMON MEASUREMENT INITIATION REQUEST message to the target RNC/BSC to initialize the common measurement procedure. Through this message, the source BSC/RNC requests the target RNC/BSC to periodically report the load information about neighboring cells. If the target RNC/BSC supports the common measurement procedure, it responds with a COMMON MEASUREMENT INITIATION RESPOSE message. Figure 4-3 shows the successful common measurement initialization procedure.

Figure 4-3 Successful common measurement initialization

SBSC/SRNC

COMMON MEASUREMENT INITIATION REQUEST

COMMON MEASUREMENT INITIATION RESPOSE

TRNC/TBSC




4-3

If the target RNC/BSC does not support the common measurement procedure, it responds with a COMMON MEASUREMENT INITIATION FAILURE message. Figure 4-4 shows the failed common measurement initialization procedure.

Figure 4-4 Failed common measurement initialization

After a common measurement is successfully initialized, the target RNC/BSC periodically sends COMMON MEASUREMENT REPORT messages to the source BSC/RNC to report the load information about neighboring cells. Figure 4-5 shows the common measurement reporting procedure.

Figure 4-5 Common measurement reporting procedure

If a neighboring cell is faulty, blocked, removed, or deactivated, the target RNC/BSC sends a COMMON MEASUREMENT FAILURE INDICATION message to the source BSC/RNC, notifying the source BSC/RNC that the common measurement procedure has failed and has to be terminated. Figure 4-6 shows the failed common measurement.

Figure 4-6 Failed common measurement

4.3 Information Exchange The information exchange procedure is based on the Iur-g interface, performed through connection-oriented signaling.

If SPTINFOEXCHG is set to Yes, and INFOEXCHGLIST is set to CELLCAPCLASS, the information exchange is enabled.

During a common measurement procedure, information is transmitted between 2G and 3G networks through the Iur-g interface. Such information includes the load information about 2G and 3G cells,




4-4

inter-RAT CS service handover support flag of a 2G cell, and inter-RAT PS service handover support flag of a 2G cell.

Load information about 2G or 3G cells A cell can be in three load states: normal, basic congestion, or overload congestion. Table 4-1 describes the rules for determining the load states of 2G cells.

Table 4-1 Rules for determining the load states of 2G cells

Transmission Direction

If… Then the Load State of the Cell Is…

Uplink load < UlLdrThrd2GCell Normal

UlLdrThrd2GCell ≤ Uplink load < UlOlcThrd2GCell Basic congestion

Uplink

Uplink load ≥ UlOlcThrd2GCell Overload congestion

Downlink load < DlLdrThrd2GCell Normal

DlLdrThrd2GCell ≤ Downlink load < DlOlcThrd2GCell Basic congestion

Downlink

Downlink load ≥ DlOlcThrd2GCell Overload congestion

Inter-RAT CS service handover support flag of a 2G cell When the TCH usage of a 2G cell is greater than or equal to the value of the InterRatCsServiceLoadHoThrd parameter or the INTERRATINBSCHOEN parameter is set to NO(No), the inter-RAT CS service handover support flag is No for a 2G cell. That is, the CS services in 3G cells are not allowed to be handed over to 2G cells. When the INTERRATINBSCHOEN parameter is set to YES(Yes) and the TCH usage of a 2G cell is smaller than the value of the InterRatCsServiceLoadHoThrd parameter, the inter-RAT CS service handover support flag is Yes for a 2G cell. That is, the CS services in 3G cells are allowed to be handed over to 2G cells.

Inter-RAT PS service handover support flag of a 2G cell When the TBF multiplexing rate of s 2G cell is lower than the value of the LOADRESELRXTHRSH parameter, the inter-RAT PS service handover support flag is Yes for a 2G cell. That is, the PS services in 3G cells are allowed to be handed over to 2G cells. Otherwise, the PS services in 3G cells are not allowed to be handed over to 2G cells.

GSM BSS 2G/3G Interoperability 5 2G/3G Inter-RAT Cell Reselection


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5 2G/3G Inter-RAT Cell Reselection 2G/3G inter-RAT cell reselection involves the cell reselection from GSM to UMTS and the cell reselection from UMTS to GSM. Cell reselection is performed mainly by the MS.

The following describes the feature GBFD-114323 GSM and UMTS Cell Reselection Based on MS State.

For MSs in idle mode, cell reselection is mainly performed to implement 2G/3G interoperability. A dual-mode MS camping on a GSM cell can reselect a UMTS cell. It measures the information of the neighboring UMTS cell, and then decides whether to reselect the UMTS cell according to cell reselection parameters.

For MSs in packet transfer mode, they can reselect a UMTS cell for data services through autonomous cell reselection, Network Assisted Cell Change (NACC), or Network Control Mode 2 (NC2). The cell reselection procedure in packet transfer mode is the same as that in idle mode. The autonomous cell reselection is performed by the MS without the intervention of the network. In NACC and NC2, the network affects the cell reselection through signaling so that the MS will camp on the desired cell.

The parameter INTERRATCELLRESELEN determines whether cell reselection between GSM and UMTS is enabled. When INTERRATCELLRESELEN is set to No, the BSS does not send the neighboring UMTS cell list and the parameters related to 2G/3G inter-RAT cell reselection. In this way, MSs in a GSM cell cannot select a UMTS cell.

5.1 Inter-RAT Cell Reselection from UMTS to GSM When an MS moves into the GSM coverage area and reselects a GSM cell, the MS initiates the location update in the GSM network. The GSM network handles the location update regardless of whether the MS is from a UMTS cell or a GSM cell.

For the BSS, the cell reselection procedure from UMTS to GSM is the same as that between GSM cells. Thus, it is not repeated in this document.

5.2 Inter-RAT Cell Reselection from GSM to UMTS The MSs in a GSM cell obtain the neighboring UMTS cell list and cell reselection parameters through System Information 2ter and System Information 2Quater, and then measures the neighboring UMTS cells according to the list and parameters. When the MS is in idle mode or packet transfer mode, the mechanism of cell reselection from the GSM cell to the UMTS cell is the same as that between GSM cells. In the GSM network, inter-RAT cell reselection from GSM to UMTS is controlled by FDDQOFF and FDDQMIN.

The MS obtains the lowest receive quality for reselecting a candidate UMTS cell through FDDQMIN and FDDQMINOFFSET. FDDQMIN and FDDQMINOFFSET do not determine the cell reselection from GSM to UMTS directly but guarantee the signal quality of the candidate UMTS cell. FDDQMIN is the minimum threshold for Ec/No for UTRAN FDD cell re-selection. If FDDQMIN is set to a higher value, the cell reselection is less likely to occur. If FDDQMIN is set to a lower value, the cell reselection is more likely to occur. FDDQMINOFFSET is the offset of the minimum threshold for Ec/No during an FDD cell reselection.

FDDQOFF refers to the signal strength difference between the candidate UMTS cell and the serving GSM cell. This parameter is a key factor for controlling the cell reselection from GSM to UMTS. When FDDQOFF is set to a small value, the cell reselection condition is easy to meet. In this way, the number of MSs that camp on the GSM cell is reduced. When FDDQOFF is set to a great value, the cell reselection condition is difficult to meet. In this way, the number of MSs that camp on the GSM cell is increased.



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FDDRSCPMIN is the minimum level threshold of UTRAN cell reselection. During the cell reselection decision from a GSM cell to an FDD cell. this parameter is used to calculate the FDD_RSCP_threshold of the target cell.

If FDD_RSCPmin is broadcast on the serving cell, FDD_RSCP_threshold = FDD_RSCPmin – min((P_MAX – 21 dBm), 3 dB).

If FDD_RSCPmin is not broadcast on the serving cell, Qrxlevmin and Pcompensation are available, FDD_RSCP_threshold = Qrxlevmin + Pcompensation + 10 dB.

If FDD_RSCPmin is not broadcast on the serving cell, Qrxlevmin and Pcompensation are not available, the default value of FDDRSCPMIN is used.

- P_MAX is the maximum RF output power of the MS (dBm) in UTRAN FDD mode.

- Qrxlevmin is the minimum required RX level in the UTRAN FDD cell (dBm).

- Pcompensation is max(UE_TXPWR_MAX_RACH – P_MAX, 0) (dB).

- UE_TXPWR_MAX_RACH is the maximum TX power level an MS may use when accessing the UTRAN FDD cell on RACH (dBm).

For the UMTS FDD cell, the measurement quantities to be used are Ec/No of the Common Pilot Channel (CPICH) and Received Signal Code Power (RSCP) of the CPICH. If the measurement result meets the following conditions within five seconds, the MS initiates the cell reselection from GSM to UMTS. If there is more than one UMTS cell that meets the conditions, the MS selects a cell with the highest RSCP as the target cell.

CPICH RSCP > RLA_C + FDDQOFF

CPICH Ec/No >= FDDQMIN – FDDQMINOFFSET

CPICH RSCP >= FDD_RSCP_threshold

Ec/No means the ratio of energy per modulating bit to the noise spectral density, which is a term in UMTS. It is equivalent to C/I in GSM.

Here, RLA_C refers to the average receive level. The RSCP of the neighboring UMTS cell must be greater than the sum of the value of FDDQOFF and the average receive level of the serving cell. In addition, the RSCP of the neighboring UMTS cell must be FDDQOFF greater than the receive level of every GSM neighboring cell.

The inter-RAT cell reselection from GSM to UMTS cannot be triggered five seconds within the cell reselection from the UMTS to the GSM. If the inter-RAT cell reselection from GSM to UMTS is triggered 15 seconds within the cell reselection from UMTS to GSM, the value of FDDQOFF must be increased by five dB.

If both the reselection condition from GSM to UMTS and the reselection condition between GSM cells are met, the MS selects the UMTS cell as the target cell.

5.3 Fast 3G Reselection at 2G CS Call Release Overview This section describes the feature GBFD-114325 Fast UMTS Reselection at GSM CS Call Release.

Normally, after an MS terminates a call in a GSM cell, it camps on the GSM cell. When a neighboring UMTS cell meets the requirements for cell reselection, the MS camps on the UMTS cell after the cell reselection. Before initiating the UMTS cell reselection, the MS must receive system information and calculate cell reselection parameters. When the Fast 3G Reselection at 2G CS Call Release feature is



5-3

activated, the BSS determines the best neighboring UMTS cell based on the measurement information on the neighboring UMTS cells after the call termination in a GSM cell. Then, the BSS sends the frequency information on the neighboring UMTS cell through a Channel Release message to the MS to instruct it to camp on the UMTS cell. In this way, the MS camps on a UMTS cell without calculating cell reselection parameters, thus accelerating cell reselection. In addition, the MS camps on the UMTS cell for a longer period, thus increasing the revenue of operators in the UMTS network.

This feature is activated when CELLSELECTAFTERCALLREL is set to YES.

A UMTS cell is classified into the UTRAN FDD cell and the UTRAN TDD cell.

Procedure Take the case of call termination by the MS as an example. Figure 5-1 shows the cell reselection procedure.

Figure 5-1 Cell reselection procedure

1. After receiving the Release Complete message from the MS, the MSC sends a Clear Command message to the BSC, instructing the BSC to instruct the BSC to release the occupied resources on the A and Um interfaces.

2. The BSC sends a Channel Release message to the MS to instruct the MS to release the TCH or SDCCH on the Um interface. The Channel Release message may carry the information element "Cell selection indicator after release of all TCH and SDCCH", which contains the information on the target neighboring UMTS cell.

3. After receiving the Channel Release message, the MS disconnects the uplink signaling link. Then, the MS sends a DISC frame to the BTS to instruct the BTS to release the TCH or SDCCH.

4. After receiving the UA message, the MS switches to idle mode and initiates cell reselection.

If... Then...

The Channel Release message contains the information element "Cell selection indicator after release of all TCH and SDCCH",

The MS attempts to camp on the cell indicated in the Channel Release message.



5-4

If... Then...

The Channel Release message does not contain the information element "Cell selection indicator after release of all TCH and SDCCH",

The MS attempts to camp on the cell where the TCH or SDCCH is already released.

5. If step 4 fails, the MS performs the normal cell reselection procedure. For details on the normal cell reselection procedure, see 5.2 Inter-RAT Cell Reselection from GSM to UMTS.

Before sending the Channel Release message, the BSC determines whether to carry the information element "Cell selection indicator after release of all TCH and SDCCH" in the message. 1. If CELLSELECTAFTERCALLREL is set to YES, the procedure proceeds to 2. Otherwise, the

procedure is complete, and the BSC sends the Channel Release message to the MS. The message does not carry the information element "Cell selection indicator after release of all TCH and SDCCH".

2. The BSC determines whether an MS supports both GSM and UMTS through the classmark. If the classmark does not indicate the MS capability of supporting the GSM/UMTS, the procedure proceeds to 3. Otherwise, the procedure is completed, and the BSC sends the Channel Release message to the MS. The message does not carry the information element "Cell selection indicator after release of all TCH and SDCCH".

3. The BSC figures out the best neighboring UMTS cell based on the related measurement report, and then the procedure proceeds to 4. If there is no measurement report or the measurement report does not contain the information on the neighboring UMTS cell, the procedure is complete, and the BSC sends the Channel Release message to the MS. The message does not carry the information element "Cell selection indicator after release of all TCH and SDCCH".

4. If the measurement report indicates a neighboring UMTS FDD cell, Cell Selection Indicator is set to UTRAN FDD Description. If the measurement report indicates a neighboring UTRAN TDD cell, Cell Selection Indicator is set to UTRAN TDD Description, and the procedure is complete. Meanwhile, the BSC sends the Channel Release message to the MS. The message contains the information element "Cell selection indicator after release of all TCH and SDCCH".

5.4 NACC and NC2 When MS is in packet transfer mode, NACC and NC2 can be performed for inter-RAT cell reselection.

If the Iur-g interface exists between the BSC and RNC, the UMTS-to-GSM NACC procedure is an optimized NACC procedureIn this case, the MS obtains the SI of the target cell directly over the Iur-g interface. The information exchange see 4.3 Information Exchange, and the parameter INFOEXCHGLIST should set to NACCRELATED.

For details, see NACC Parameter Description and NC2 Parameter Description.

GSM BSS 2G/3G Interoperability 6 2G/3G Inter-RAT Handover


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6 2G/3G Inter-RAT Handover 2G/3G inter-RAT handover involves the handover from GSM to UMTS and the handover from UMTS to GSM. The handover is controlled mainly by the network.

For MSs in dedicated mode, cell reselection is mainly performed to implement inter-RAT handover, including emergency handover, better cell handover, inter-RAT load handover, and inter-RAT service handover.

Emergency handover refers to the handover that is triggered when the call cannot be processed in the serving cell due to poor coverage or other reasons during the CS service of the dual-mode MS. For example, when an MS making a call in the GSM cell is moving outside the cell, the emergency handover is triggered to avoid call drops.

Better cell handover refers to the handover that is triggered when the signal quality of the neighboring cell is better than that of the serving cell, so that better service quality and user experience can be achieved. For example, when the signal quality of a UMTS cell is better than that of the serving GSM cell, MSs in the serving cell can be handed over to the UMTS cell to achieve higher voice quality.

Inter-RAT load handover refers to the handover wherein parts of the calls in the GSM serving cell are handed over to a UMTS cell or parts of the calls in the UMTS serving cell are handed over to a GSM cell due to high load on the serving cell. For an incoming inter-RAT handover to a GSM cell, if the traffic load on the target GSM cell is also high, the target cell rejects the handover to avoid ping-pong handovers.

In the inter-RAT service handover, the operator can choose the network that the MS will access through the MSC. For a call initiating access request in a GSM cell, if the MSC indicates that the service handover should be performed, the BSS hands over the call to the UMTS cell. If the MSC indicates that call should not be handed over to a UMTS call, the BSS does not hand over the call to a UMTS cell when a handover is needed during the call.

6.1 Inter-RAT Handover from UMTS to GSM MSs in dedicated mode can be handed over from a UMTS cell to a GSM cell. The handover decision and handover procedure are controlled by the RNC. The BSS considers the incoming handover from UMTS to GSM as a general inter-BSC handover.

The parameter INTERRATINBSCHOEN determines whether inter-RAT handover from UMTS to GSM is enabled. If INTERRATINBSCHOEN is set to No, the BSS rejects all the requests for the handover from UMTS to GSM.

6.2 Inter-RAT Handover from GSM to UMTS The parameter INTERRATOUTBSCHOEN determines whether inter-RAT handover from GSM to UMTS is enabled. If INTERRATOUTBSCHOEN is set to NO(No), the BSS rejects all the requests for the handover from GSM to UMTS and does not take the UMTS cell as a target cell.

In dedicated mode, the MS obtains the neighboring UMTS cell list and other information from Measurement Information. Then, the MS reports the measurement result to the BSS through the measurement report. After receiving the measurement result, the BSS determines whether to initiate the inter-RAT handover from GSM to UMTS based on the measurement result and the handover algorithm.

The inter-RAT handover from GSM to UMTS can be classified into emergency handover and better 3G cell handover. The algorithm for the emergency handover from GSM to UMTS is the same as that for the general emergency handover. For details, see Handover Parameter Description.

In the GSM network, the parameter HOOPTSEL determines whether the GSM cell or the UMTS cell is preferentially selected as the target cell.



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When HOOPTSEL is set to Pre_2G_Cell(Preference for 2G cell), the BSC preferentially selects a GSM cell as the target cell.

When HOOPTSEL is set to Pre_3G_Cell(Preference for 3G cell), the BSC preferentially selects a UMTS cell as the target cell.

If HOOPTSEL is set to Pre_2G_CellThres(Preference 2G cell by thresh), the BSC determines the target cell according to the levels of the neighboring GSM cells and the value of HOPRETH2G. If no neighboring GSM cell has a level higher than HOPRETH2G, the BSC selects a UMTS cell as the target cell.

Better 3G cell handover can be performed only when both INTERRATOUTBSCHOEN and BET3GHOEN are set to YES(Yes). As the measurement result of the UMTS cell can be reported through RSCP or Ec/No, the ways for handover decision differ accordingly.

When the value of FDDREP is RSCP(RSCP), the better 3G cell handover is triggered if the following condition is met for the period specified by HODURT3G within HOSTAT3G. CPICH RSCP > HORSCPTH3G

When the value of FDDREP is Ec/N0, the better 3G cell handover is triggered if the following condition is met for the period specified by HODURT3G within HOSTAT3G. CPICH Ec/No > HOECNOTH3G

6.3 2G/3G Service Distribution and Load Balancing in Access State Overview With the co-existence of 2G and 3G networks, operators can provide more diversified services. The QoS-based service distribution feature is introduced to optimize the utilization of resources in 2G and 3G networks. For example, voice services and low-rate data services are distributed to the 2G network, whereas high-rate data services are distributed to the 3G network to achieve high peak throughput.

In addition, in the case of co-existence of 2G and 3G networks, the traffic load in the two networks is different. The 2G/3G load balancing feature is introduced to balance the load between the two networks. In this manner, the system capacity is increased, but there is no impact of high load on the system, and the 2G/3G network resources are efficiently used (GBFD-114321 GSM and WCDMA Service Based Handover).

When an MS accesses the network through a 2G cell, the BSC hands over the MS (a dual-mode MS) performing high-rate data service to the target 3G cell according to the load in the target 3G cell and retains the low-rate services in the 2G cell. If the MS accesses the network through a 2G cell and the 2G cell is congested, the BSC redirects the MS to the target 3G cell according to the load in the target 3G cell.

Related Algorithms When an MS accesses the network through a 2G cell, the BSC selects an inter-RAT handover algorithm based on the setting of the InterRatServiceLoadHoSwitch parameter, if the INTERRATOUTBSCHOEN parameter is set to YES(Yes).

When the InterRatServiceLoadHoSwitch parameter is set to CnService-based(CN Service-based), the BSC performs different processing based on the setting of the Service Handover IE in the ASSIGNMENT REQUEST message received from the Core Network (CN). The details are as follows: − If the value of the Service Handover IE is Handover to UTRAN or cdma2000 should be performed, it indicates that the MS should be handed over to a 3G cell. In this case, the BSC selects a target 3G cell from the list of neighboring cells and starts the handover from 2G to 3G.



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− If the value of the Service Handover IE is Handover to UTRAN or cdma2000 should not be performed, it indicates that a 2G cell should be preferentially selected as the serving cell. In this case, the BSC does not start the handover from 2G to 3G. If a handover is required during the call, a 2G cell is preferentially selected as the target cell.

− If the value of the Service Handover IE is Handover to UTRAN or cdma2000 shall not be performed, it indicates that the MS must not be handed over to a 3G cell. In this case, the BSC will not hand over the MS to a 3G cell, and will select only a 2G cell as the target cell if a handover is required.

When the InterRatServiceLoadHoSwitch parameter is set to Service-based(Service-based), the BSC removes the candidate 3G cells that experience basic congestion in uplink or downlink and admits the MS to the 2G cell if the MS performs only CS voice services after accessing the network.

When the InterRatServiceLoadHoSwitch parameter is set to Load-based(Load-based) and the value of the Service Handover IE is handover to UTRAN or cdma2000 should be performed, the BSC selects a candidate 3G cell that meets the following condition in both uplink and downlink as the target cell. The details are as follows: − G2GLoadAdjustCoeff x Current load in the serving 2G cell – 10 x load in the neighboring 3G cell ≥ 10 x G2G3GLdBlcDeltaThrd – 1,000

Then, the BSC selects the best neighboring 3G cell as the target cell and starts the directed retry to the 3G cell. If there is no 3G cell that meets the preceding condition in uplink and downlink, the BSC admits the MS to the 2G cell.

If there are no candidate 3G cells or if the directed retry to the target 3G cell fails, the BSC starts a reassignment procedure in a 2G cell.

When the InterRatServiceLoadHoSwitch parameter is set to Dynamic-based(Dynamic Service/Load-based), the BSC selects a proper target cell by using the system service distribution algorithm if the load in the serving cell is in the normal state. If the load in the serving cell is in other states, the BSC selects a target cell by using the system load balancing algorithm.

6.4 Inter-RAT Load-based Handover in Connect State Overview This section describes the feature GBFD-114322 GSM and WCDMA Load Based Handover.

In the case of co-existence of 2G and 3G networks, there is a possibility that a network is congested due to insufficient resources, whereas the other network has only a light traffic. The inter-RAT load-based handover in connected state feature is introduced to solve this problem. This feature enables the efficient use of the resources in 2G and 3G networks and balances the load between 2G and 3G networks. In this manner, the system capacity is increased, but there is no impact of high load on the system.

Related Algorithms When the OutSysLoadHoEn parameter is set to YES(Yes) and the MS or UE supports inter-RAT handover, an inter-RAT load-based handover in connected state is triggered when the following conditions are met:

The CPU usage of the system is smaller than or equal to the value of the SYSFLOWLEV parameter. The current load in the serving cell is greater than or equal to the value of the TRIGTHRES parameter. The value of the Service Handover IE in the ASSIGNMENT REQUEST message received from the CN is not handover to UTRAN or cdma2000 shall not be performed.

The candidate neighboring 3G cells must meet the following condition:



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G2GLoadAdjustCoeff x Load in the current 2G serving cell – 10 x Load in the neighboring 3G cell ≥ G2G3GLdBlcDeltaThrd – 1,000

In the case that the FDDREP parameter is set to RSCP(RSCP), the target 3G cell must meet the following conditions: − InterRATLoadHoRSCPStart – LOADOFFSET < CPICH RSCP < InterRATLoadHoRSCPStart − CPICH RSCP > IntRATLoadHORSCPThr

In the case that the FDDREP parameter is set to EcN0(Ec/N0), the target 3G cell must meet the following conditions: − InterRATLoadHoEcNoStart – LOADOFFSET < CPICH Ec/No < InterRATLoadHoEcNoStart − CPICH Ec/No > IntRATLoadHOEcNoThr

If a candidate neighboring 3G cell does not meet the preceding condition, the neighboring 3G cell is removed from the list of candidate cells.

If the load information about a neighboring 3G cell is invalid, the neighboring 3G cell is not considered as a candidate cell.

If there is at least one candidate 3G cell that meets the preceding condition, the BSC selects the best candidate cell as the target cell.

GSM BSS 2G/3G Interoperability 7 Engineering Guidelines


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7 Engineering Guidelines Related Parameters in the System Information 2G/3G interoperability requires the support of MSs. After 2G/3G interoperability is enabled, the early classmark sending function should be enabled so that MSs will report their support capabilities as soon as possible. It is recommended that ECSC be set to Yes.

When setting the inter-RAT cell reselection parameters and handover thresholds, take the consistency between the GSM parameters and UMTS parameters into consideration to avoid ping-pong handovers.

The network can control the cell reselection between GSM and UMTS through related parameters in the system information. If the MS is preferred to access UMTS when available, you are advised to set QI to 7, that is, the UMTS cell search is always performed.

The value of FDDQOFF has a great impact on cell reselection. If the MS is preferred to camp on the UMTS, you are advised to change the value of FDDQOFF so that the actual offset is a negative value.

When the value of FDDQOFF is smaller than 8, the corresponding actual offset is smaller than 0.

Neighboring UMTS Cell Configuration To enable the 2G/3G interoperability, neighboring UMTS cells must be configured. The UMTS cell can be configured at the BSS side by adding external 3G cells. One GSM cell can be configured with a maximum of 64 neighboring UMTS cells. Those cells can work in three frequencies and a maximum of 32 cells can work in the same frequency. If the UMTS cell is a WCDMA cell, set UTRANCELLTYPE to FDD(FDD).

GSM BSS 2G/3G Interoperability 8 Parameters


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8 Parameters Table 8-1 Parameter description

Parameter ID NE MML Description

Send2QuterFlag BSC6900 SET OTHSOFTPARA(Optional)

Meaning: This parameter specifies whether the SI Type 3 message contains the 2QUATER indicator. GUI Value Range: NO(No), YES(Yes) Actual Value Range: NO, YES Unit: None Default Value: YES

QI BSC6900 SET GCELLCCUTRANSYS(Optional)

Meaning: This parameter specifies the level threshold for cell reselection in idle mode. In idle mode, if the signal level of the serving cell is below [0, 7] or above [8, 15], the MS starts to search for 3G cells. For example, if this parameter is set to 5 and if the signal level of the serving cell is lower than 5, the MS starts to search for 3G cells; if this parameter is set to 10 and if the signal level of the serving cell is above 10, then the MS starts to search for 3G cells. The values of this parameter correspond to the following decibel values: 0: -98 dBm 1: -94 dBm 2: -90 dBm 3: -86 dBm 4: -82 dBm 5: -78 dBm 6: -74 dBm 7: (always), that is, the MS keeps searching for 3G cells 8: -78 dBm 9: -74 dBm 10: -70 dBm 11: -66 dBm 12: -62 dBm 13: -58 dBm 14: -54 dBm 15: Positive infinity (never), that is, the MS does not search for 3G cells. GUI Value Range: 0~15 Actual Value Range: -98, -94, -90, -86, -82, -78, -74, (always), -78, -74, -70, -66, -62, -58, -54, Positive infinity(never) Unit: None Default Value: 15

QP BSC6900 SET GCELLCCUTRANSY

Meaning: This parameter specifies one threshold of the signal level for cell reselection in packet transfer mode.



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S(Optional) In packet transfer mode, if the signal level of the serving cell is below [0, 7] or above [8, 15], the MS starts to search for 3G cells. For example, if this parameter is set to 5 and if the signal level of the serving cell is lower than 5, the MS starts to search for 3G cells; if this parameter is set to 10 and if the signal level of the serving cell is above 10, then the MS starts to search for 3G cells. The values of this parameter correspond to the following decibel values: 0: -98 dBm 1: -94 dBm ... 6: -74 dBm 7: (always) 8: -78 dBm 9: -74 dBm ... 14: -54 dBm 15: Positive infinity (never) GUI Value Range: 0~15 Actual Value Range: -98, -94, -90, -86, -82, -78, -74, (always), -78, -74, -70, -66, -62, -58, -54, Positive infinity(never) Unit: None Default Value: 15

QSEARCHC BSC6900 SET GCELLCCUTRANSYS(Optional)

Meaning: In connection mode, if the signal level is below [0-7] or above [8-15], the MS starts to search for 3G cells. For example, if this parameter is set to 5 and if the signal level of the serving cell is lower than 5, the MS starts to search for 3G cells; if this parameter is set to 10 and if the signal level of the serving cell is above 10, then the MS starts to search for 3G cells. 0: -98 dBm 1: -94 dBm ... 6: -74 dBm 7: (always) 8: -78 dBm 9: -74 dBm ... 14: -54 dBm 15: Positive infinity (never) GUI Value Range: 0~15 Actual Value Range: -98, -94, -90, -86, -82, -78, -74, (always), -78, -74, -70, -66, -62, -58, -54, Positive infinity(never) Unit: None Default Value: 15



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QCI BSC6900 SET GCELLCCUTRANSYS(Optional)

Meaning: This parameter specifies the threshold of the signal level for cell reselection in connection mode before ""Qsearch C"" is obtained. GUI Value Range: Use_Qsearch_I(Use Qsearch_I), Always(Always) Actual Value Range: Use_Qsearch_I, Always Unit: None Default Value: Use_Qsearch_I

UlLdrThrd2GCell BSC6900 SET GCELLHOINTERRATLDB(Optional)

Meaning: When the uplink load of a cell is larger than the value of this parameter and is smaller than "2G Cell UL Overload Congest Thred", the uplink of the cell is in the basic congestion status. GUI Value Range: 1~100 Actual Value Range: 1~100 Unit: None Default Value: 90

UlOlcThrd2GCell BSC6900 SET GCELLHOINTERRATLDB(Optional)

Meaning: When the uplink load of a cell is greater than the value, the uplink of the cell is in the overload congestion status. GUI Value Range: 1~100 Actual Value Range: 1~100 Unit: None Default Value: 100

DlLdrThrd2GCell BSC6900 SET GCELLHOINTERRATLDB(Optional)

Meaning: When the downlink load of a cell is larger than the value of this parameter and is smaller than "2G Cell DL Overload Congest Thred", the downlink of the cell is in the basic congestion status. GUI Value Range: 1~100 Actual Value Range: 1~100 Unit: None Default Value: 90

DlOlcThrd2GCell BSC6900 SET GCELLHOINTERRATLDB(Optional)

Meaning: When the downlink load of a cell is greater than the value, the downlink of the cell is in the overload congestion status. GUI Value Range: 1~100 Actual Value Range: 1~100 Unit: None Default Value: 100

InterRatCsServiceLoadHoThrd

BSC6900 SET GCELLHOINTERRATLDB(Optional)

Meaning: Threshold for setting the flag of accepting inter-RAT CS service handover of a 2G cell GUI Value Range: 1~100 Actual Value Range: 1~100 Unit: None Default Value: 80

INTERRATINBSCHOEN

BSC6900 SET GCELLHOBASIC(Opti

Meaning: This parameter specifies whether the handover from 3G cells to 2G cells is allowed.



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onal) GUI Value Range: NO(No), YES(Yes) Actual Value Range: NO, YES Unit: None Default Value: NO

LOADRESELRXTHRSH

BSC6900 SET GCELLNC2PARA(Optional)

Meaning: When the uplink load or downlink load of the target cell is lower than this threshold, it can accept the MSs from the serving cell due to load reselection. GUI Value Range: 0~100 Actual Value Range: 0~100 Unit: % Default Value: 60

INTERRATCELLRESELEN

BSC6900 SET GCELLHOBASIC(Optional)

Meaning: This parameter specifies whether the reselection from 2G cells to 3G cells is allowed.GUI Value Range: NO(No), YES(Yes) Actual Value Range: NO, YES Unit: None Default Value: NO

FDDQOFF BSC6900 SET GCELLCCUTRANSYS(Optional)

Meaning: This parameter specifies one of the thresholds of the signal level for 3G cell reselection. A FDD cell becomes a candidate cell if all the following conditions are met for five consecutive seconds: 1.Receive level of the FDD cell > Average receive level of the current serving cell + "FDD Q offset"; The FDD cell meets the following condition in the case of any neighboring 2G cell: Receive level of the FDD cell > Receive level of any neighboring 2G cell + "FDD Q offset"; 2. Ec/No of the FDD cell > "FDD Qmin" - "FDD Qmin Offset"; 3. Receive level of the FDD cell > "RSCP Threshold"; If multiple FDD cells meet the preceding conditions, the MS reselects the cell with the strongest receive level. See 3GPP TSs 45.008 and 25.304. The values of this parameter correspond to the following decibel values: 0: - (always select a cell if acceptable) 1: -28 dB, 2: -24 dB, ... 15: 28 dB. GUI Value Range: 0~15 Actual Value Range: Negative infinity, -28~28, step: 4 Unit: dB Default Value: 8

FDDQMIN BSC6900 SET Meaning: This parameter specifies one of the



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GCELLCCUTRANSYS(Optional)

parameters for FDD cell reselection. A FDD cell becomes a candidate cell if all the following conditions are met for five consecutive seconds: 1.Receive level of the FDD cell > Average receive level of the current serving cell + "FDD Q offset"; The FDD cell meets the following condition in the case of any neighboring 2G cell: Receive level of the FDD cell > Receive level of any neighboring 2G cell + "FDD Q offset"; 2. Ec/No of the FDD cell > "FDD Qmin" - "FDD Qmin Offset"; 3. Receive level of the FDD cell > "RSCP Threshold"; If multiple FDD cells meet the preceding conditions, the MS reselects the cell with the strongest receive level. See 3GPP TSs 45.008 and 25.304. The values of this parameter correspond to the following decibel values: 0: -20 dB, 1: -6 dB, 2: -18 dB, 3: -8 dB, 4: -16 dB, 5: -10 dB, 6: -14 dB, 7: -12 dB. GUI Value Range: 0~7 Actual Value Range: -20, -6, -18, -8, -16, -10, -14, -12 Unit: dB Default Value: 0

CELLSELECTAFTERCALLREL

BSC6900 SET GCELLCCAD(Optional)

Meaning: This parameter specifies whether to allow a mobile phone to preferentially camp on a 3G cell after a call is terminated in the areas covered by both the GSM network and the UMTS network. GUI Value Range: NO(No), YES(Yes) Actual Value Range: NO, YES Unit: None Default Value: NO

INTERRATOUTBSCHOEN

BSC6900 SET GCELLHOBASIC(Optional)

Meaning: This parameter specifies whether the handover from 2G cells to 3G cells is allowed. GUI Value Range: NO(No), YES(Yes) Actual Value Range: NO, YES Unit: None Default Value: NO

HOOPTSEL BSC6900 SET GCELLHOUTRANFDD(Optional)

Meaning: This parameter specifies whether a 2G cell or to a 3G cell is preferentially selected as the target cell for handover. When this parameter



8-6

is set to Pre_2G_Cell, the BSC preferentially selects a 2G candidate cell as the target cell for handover. When this parameter is set to Pre_3G_Cell, the BSC preferentially selects a 3G candidate cell as the target cell for handover. When this parameter is set to Pre_2G_CellThres, the BSC preferentially selects a neighboring 3G cell as the handover target cell if the receive level of the neighboring 2G cell that ranks the first in the candidate cell list is equal to or smaller than "HO Preference Threshold for 2G Cell". Otherwise, the BSC preferentially selects a neighboring 2G cell as the handover target cell. GUI Value Range: Pre_2G_Cell(Preference for 2G cell), Pre_3G_Cell(Preference for 3G cell), Pre_2G_CellThres(Preference 2G cell by thresh)Actual Value Range: Pre_2G_Cell, Pre_3G_Cell, Pre_2G_CellThres Unit: None Default Value: Pre_2G_CellThres

HOOPTSEL BSC6900 SET GCELLHOUTRANTDD(Optional)

Meaning: This parameter specifies whether a 2G cell or to a 3G cell is preferentially selected as the target cell for handover. When this parameter is set to Pre_2G_Cell, the BSC preferentially selects a 2G candidate cell as the target cell for handover. When this parameter is set to Pre_3G_Cell, the BSC preferentially selects a 3G candidate cell as the target cell for handover. When this parameter is set to Pre_2G_CellThres, the BSC preferentially selects a neighboring 3G cell as the handover target cell if the receive level of the neighboring 2G cell that ranks the first in the candidate cell list is equal to or smaller than "HO Preference Threshold for 2G Cell". Otherwise, the BSC preferentially selects a neighboring 2G cell as the handover target cell. GUI Value Range: Pre_2G_Cell(Preference for 2G cell), Pre_3G_Cell(Preference for 3G cell), Pre_2G_CellThres(Preference 2G cell by thresh)Actual Value Range: Pre_2G_Cell, Pre_3G_Cell, Pre_2G_CellThres Unit: None Default Value: Pre_2G_CellThres

HOPRETH2G BSC6900 SET GCELLHOUTRANFDD(Optional)

Meaning: If the receive level of the neighboring 2G cell that ranks the first in the candidate cell list is equal to or smaller than this threshold, the BSC preferentially selects a neighboring 3G cell as the handover target cell. Otherwise, the BSC preferentially selects a neighboring 2G cell as the handover target cell. GUI Value Range: 0~63 Actual Value Range: 0~63



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Unit: dB Default Value: 25

HOPRETH2G BSC6900 SET GCELLHOUTRANTDD(Optional)

Meaning: If the receive level of the neighboring 2G cell that ranks the first in the candidate cell list is equal to or smaller than this threshold, the BSC preferentially selects a neighboring 3G cell as the handover target cell. Otherwise, the BSC preferentially selects a neighboring 2G cell as the handover target cell. GUI Value Range: 0~63 Actual Value Range: 0~63 Unit: dB Default Value: 25

BET3GHOEN BSC6900 SET GCELLHOUTRANFDD(Optional)

Meaning: This parameter specifies whether to allow 3G better cell handover algorithm. GUI Value Range: NO(No), YES(Yes) Actual Value Range: NO, YES Unit: None Default Value: NO

BET3GHOEN BSC6900 SET GCELLHOUTRANTDD(Optional)

Meaning: This parameter specifies whether to allow 3G better cell handover algorithm. GUI Value Range: NO(No), YES(Yes) Actual Value Range: NO, YES Unit: None Default Value: NO

FDDREP BSC6900 SET GCELLCCUTRANSYS(Optional)

Meaning: This parameter specifies whether Ec/No or RSCP is used for the measurement report on a FDD cell. Ec/No stands for the signal-to-noise ratio. RSCP stands for the received signal code power. GUI Value Range: RSCP(RSCP), EcN0(Ec/N0)Actual Value Range: RSCP, EcN0 Unit: None Default Value: RSCP

HODURT3G BSC6900 ADD G3GNCELL(Optional)MOD G3GNCELL(Optional)

Meaning: According to the P/N rule, if the conditions for the handover to a better 3G cell are met for P seconds within N seconds, the handover is triggered. This parameter specifies the number P. GUI Value Range: 1~32 Actual Value Range: 0.5~16, step:0.5 Unit: s Default Value: 8

HOSTAT3G BSC6900 ADD G3GNCELL(Optional)MOD G3GNCELL(Optional)

Meaning: According to the P/N rule, if the conditions for the handover to a better 3G cell are met in P of N measurement reports, the handover is triggered. This parameter specifies the number N. GUI Value Range: 1~32 Actual Value Range: 0.5~16, step:0.5 Unit: s



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Default Value: 10

HORSCPTH3G BSC6900 SET GCELLHOUTRANFDD(Optional)

Meaning: The 3G better cell handover is triggered only when the RSCP of a neighboring 3G cell is greater than this threshold for a period of time. GUI Value Range: 0~63 Actual Value Range: 0~63 Unit: dB Default Value: 50

HORSCPTH3G BSC6900 SET GCELLHOUTRANTDD(Optional)

Meaning: The 3G better cell handover is triggered only when the RSCP of a neighboring 3G cell is greater than this threshold for a period of time. GUI Value Range: 0~63 Actual Value Range: 0~63 Unit: dB Default Value: 50

HOECNOTH3G BSC6900 SET GCELLHOUTRANFDD(Optional)

Meaning: The 3G better cell handover can be triggered only when the Ec/No of a neighboring 3G cell is greater than this threshold for a period of time. GUI Value Range: 0~49 Actual Value Range: 0~49 Unit: dB Default Value: 35

InterRatServiceLoadHoSwitch


Meaning: When this parameter is set to Service-based, the inter-RAT handover is triggered on the basis of the service distribution. In this case, the target cell is selected according to the traffic load. When this parameter is set to Load-based, the inter-RAT handover is triggered on the basis of the load balance. In this case, the target cell is selected according to the traffic load on the target cell and the load difference between 2G and 3G cells. When this parameter is set to Dynamic Service/Load based, the target cell is dynamically selected by using the service-based algorithm or the load-based algorithm according to the traffic load on the cell. When this parameter is set to CN Service-based, the inter-RAT handover decision is made on the basis of the service attribute of the core network. When this parameter is set to OFF, no inter-RATservice handover or inter-RAT load handover in the access state is performed. GUI Value Range: Service-based(Service-based), Load-based(Load-based), Dynamic-based(Dynamic Service/Load-based), CnService-based(CN Service-based),



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OFF(OFF) Actual Value Range: Service-based, Load-based, Dynamic-based, CnService-based, OFF Unit: None Default Value: OFF

G2GLoadAdjustCoeff


Meaning: Coefficient used to modulate the load level of a 2G system so that the load level of the 2G system can be compared with that of a 3G system. GUI Value Range: 0~100 Actual Value Range: 0~100 Unit: None Default Value: 10

G2G3GLdBlcDeltaThrd

BSC6900 SET OTHSOFTPARA(Optional)

Meaning: If the load balance between a 2G cell and a 3G cell is greater than the threshold, load balance is triggered. GUI Value Range: 0~200 Actual Value Range: -100~100 Unit: % Default Value: 110

OutSysLoadHoEn BSC6900 SET GCELLHOINTERRATLDB(Optional)

Meaning: This parameter specifies whether to allow the inter-RAT load handover in connection mode (after the assignment is complete). GUI Value Range: NO(No), YES(Yes) Actual Value Range: NO, YES Unit: None Default Value: NO

SYSFLOWLEV BSC6900 SET GCELLHOAD(Optional)

Meaning: System flux thresholds correspond to the system flux obtained based on message packets, CPU load, and FID queuing load. The system flux level is the current flux control level of the system. 0-11: There are 12 flow control levels. Where, 0 indicates the lowest level and 11 indicates the highest level. A load handover is allowed only when the system flux is lower than the value of this parameter. The handover performed over the maximum threshold may have tremendous impacts on the system. Thus, this parameter should not be set to a higher value. 1) The flow control level algorithm for the assigned system messages: [(Average Message Usage - Inner Flow Control Discard Begin Threshold)/(Inner Flow Control Discard All Threshold - Inner Flow Control Discard Begin Threshold) x 100]/10+1 (round-down for division operation). If the value is smaller than Inner Flow Control Discard Begin Threshold, Level 0 is used. If the value is equal to or greater than Inner Flow Control Discard



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Begin Threshold, the level is calculated. The value range is from 0 to 11. 2) Flow control threshold for the CPU to start to discard the channel access messages and paging messages: 80%. Flow control threshold for the CPU to discard all channel access messages and paging messages: 100%. CPU usage smaller than 80% corresponds to level 0. CPU usage equal to or greater than CPU flow control threshold 80% corresponds to level 2. An increase of 5% means an increase of 2 levels. Level 10 is the highest. The level value can be 0, 2, 4, 6, 8, and 10. GUI Value Range: 0, 8~11 Actual Value Range: 0, 8~11 Unit: None Default Value: 10

TRIGTHRES BSC6900 SET GCELLHOAD(Optional)

Meaning: The load handover is triggered when the traffic load in a cell is greater than the value of this parameter. GUI Value Range: 0~100 Actual Value Range: 0~100 Unit: None Default Value: 90

InterRATLoadHoRSCPStart


Meaning: Initial RSCP value of the inter-RAT load-based handover band GUI Value Range: 0~91 Actual Value Range: 0~91 Unit: dB Default Value: 91

LOADOFFSET BSC6900 SET GCELLHOAD(Optional)

Meaning: In the handover algorithm of the first generation, load handovers can be performed only when the receive level of the current serving cell is in the range "Edge HO DL RX_LEV Threshold" to "Edge HO DL RX_LEV Threshold" + "Load HO Bandwidth". In the handover algorithm of the second generation, load handovers can be performed only when the level difference between the neighboring cell and the serving cell is between ("Inter-cell HO Hysteresis" - 64) - "Load HO Bandwidth" and ("Inter-cell HO Hysteresis" - 64).GUI Value Range: 0~63 Actual Value Range: 0~63 Unit: dB Default Value: 25

IntRATLoadHORSCPThr


Meaning: Minimum RSCP value of a 3G cell during the load-based GSM-to-UMTS handoverGUI Value Range: 0~91 Actual Value Range: 0~91



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Unit: dB Default Value: 30

InterRATLoadHoEcNoStart


Meaning: Initial EcNo value of the inter-RAT load-based handover band GUI Value Range: 0~49 Actual Value Range: 0~49 Unit: dB Default Value: 49

IntRATLoadHOEcNoThr


Meaning: Minimum Ec/No value of a 3G cell during the load-based GSM-to-UMTS handoverGUI Value Range: 0~49 Actual Value Range: 0~49 Unit: dB Default Value: 25

ECSC BSC6900 SET GCELLCCBASIC(Optional)

Meaning: The early classmark sending control (ECSC) parameter specifies whether the MSs in a cell use early classmark sending. After a successful immediate assignment, the MS sends additional classmark information to the network as early as possible. The additional classmark information mainly contains the CM3 (classmark 3) information. The CM3 (classmark 3) information contains the frequency band support capability of the MS (used for the future channel assignment), power information about each frequency band supported by the MS (used for the handover between different frequency bands), and encryption capability of the MS. GUI Value Range: NO(No), YES(Yes) Actual Value Range: NO, YES Unit: None Default Value: YES

UTRANCELLTYPE BSC6900 ADD GEXT3GCELL(Mandatory) MOD GEXT3GCELL(Optional)

Meaning: This parameter specifies the type of a 3G cell. A cell type can be Frequency Division Duplex (FDD) or Time Division Duplex (TDD). GUI Value Range: FDD(FDD), TDD(TDD) Actual Value Range: FDD, TDD Unit: None Default Value: None

FDDQMINOFFSET BSC6900 SET GCELLCCUTRANSYS(Optional)

Meaning: Offset of the minimum threshold for Ec/No during a FDD cell reselection. A FDD cell becomes a candidate cell if all the following conditions are met for five consecutive seconds: 1.Receive level of the FDD cell > Average receive level of the current serving cell + "FDD Q offset"; The FDD cell meets the following condition in the case of any neighboring 2G cell: Receive level of the FDD cell > Receive level of any neighboring 2G cell + "FDD Q offset";



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2. Ec/No of the FDD cell > "FDD Qmin" - "FDD Qmin Offset"; 3. Receive level of the FDD cell > "RSCP Threshold"; If multiple FDD cells meet the preceding conditions, the MS reselects the cell with the strongest receive level. See 3GPP TSs 45.008 and 25.304. GUI Value Range: 0~7 Actual Value Range: 0~7 Unit: dB Default Value: 0

FDDRSCPMIN BSC6900 SET GCELLCCUTRANSYS(Optional)

Meaning: Minimum level threshold of UTRAN cell reselection. During the cell reselection decision from a GSM cell to a FDD cell, this parameter is used to calculate the RSCP threshold of the target cell. A FDD cell becomes a candidate cell if all the following conditions are met for five consecutive seconds: 1.Receive level of the FDD cell > Average receive level of the current serving cell + "FDD Q offset"; The FDD cell meets the following condition in the case of any neighboring 2G cell: Receive level of the FDD cell > Receive level of any neighboring 2G cell + "FDD Q offset"; 2. Ec/No of the FDD cell > "FDD Qmin" - "FDD Qmin Offset"; 3. Receive level of the FDD cell > "RSCP Threshold"; If multiple FDD cells meet the preceding conditions, the MS reselects the cell with the strongest receive level. See 3GPP TSs 45.008 and 25.304. The values of this parameter correspond to the following decibel values: 0 = -114 dBm, 1 = -112 dBm, 2 = -110 dBm, ... 14 = -86 dBm, 15 = -84 dBm. GUI Value Range: 0~15 Actual Value Range: -114~-84, step: 2 Unit: dBm Default Value: 6

SPTCOMMMEAS BSC6900 ADD GNRNC(Optional) MOD GNRNC(Optional)

Meaning: Whether to support the common bidirectional measurement procedure on the Iur-g interface. GUI Value Range: NO(No Support), YES(Support) Actual Value Range: NO, YES



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Unit: None Default Value: NO

SPTINFOEXCHG BSC6900 ADD GNRNC(Optional) MOD GNRNC(Optional)

Meaning: Whether to support the bidirectional information exchange procedure on the Iur-g interface. GUI Value Range: NO(No Support), YES(Support) Actual Value Range: NO, YES Unit: None Default Value: NO

INFOEXCHGLIST BSC6900 ADD GNRNC(Mandatory) MOD GNRNC(Mandatory)

Meaning: Information exchange content to be supported GUI Value Range: CELLCAPCLASS(Cell Capacity Info), NACCRELATED(NACC Info) Actual Value Range: CELLCAPCLASS, NACCRELATED Unit: None Default Value: CELLCAPCLASS

GSM BSS 2G/3G Interoperability 9 Counters


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9 Counters For the counters, see the BSC6900 GSM Performance Counter Reference.

GSM BSS 2G/3G Interoperability 10 Glossary


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10 Glossary For the acronyms, abbreviations, terms, and definitions, see the Glossary.

GSM BSS 2G/3G Interoperability 11 Reference Documents


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11 Reference Documents [1] 3GPP TS 45.008 Radio subsystem link control [2] 3GPP TS 44.018 Mobile radio interface layer 3 specification; Radio Resource Control (RRC)

protocol [3] 3GPP TS 48.008 Mobile Switching Centre - Base Station system (MSC-BSS) interface; Layer 3

specification [4] BSC6900 Feature List [5] BSC6900 Optional Feature Description [6] GBSS Reconfiguration Guide [7] BSC6900 GSM Parameter Reference [8] BSC6900 GSM MML Command Reference [9] BSC6900 GSM Performance Counter Reference

2g3g interoperability

Documents

basic congestion

overload congestion

packet transfer

cell ho hysteresis

cell selection

autonomous

load ho bandwidth

channel access