FN1168 Multiple PLMN and Inter-PLMN Handover Support

Feature 1168: Multiple PLMN andInter-PLMN Handover Support

DN99627239Issue 2-1 en

# Nokia Siemens Networks 1 (25)

Nokia Siemens Networks DX MSC / MSS / DXHLR, Rel. M14.3, Feature Documentation, v4

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2 (25) # Nokia Siemens Networks DN99627239Issue 2-1 en

Feature 1168: Multiple PLMN and Inter-PLMN Handover Support

Contents

Contents 3

List of tables 4

List of figures 5

1 Feature description 71.1 Introduction 71.2 Benefits for the operator 81.3 Requirements for using the feature 91.3.1 Software 91.3.2 Hardware 91.3.3 Products 91.4 Functionality 91.4.1 General 91.4.2 Control of normal and subsequent Inter-PLMN handover 91.4.3 Feature usage requirements and limitations 161.4.4 Files 171.4.5 Parameters 171.4.6 Statistics 171.4.7 Charging 181.5 Capacity 191.6 Restrictions 191.7 Related and interworking features 191.8 Compliance 201.9 Operator interfaces 201.9.1 MMLs 201.9.2 Alarms 231.10 Subscriber interfaces 231.11 External interfaces 241.11.1 Network elements 24

2 Main changes in Feature 1168: Multiple PLMN and Inter-PLMNHandover Support 25

2.1 Changes in the feature 252.1.1 Changes in the document 25



Contents

List of tables



List of figures

Figure 1. Multiple PLMN architecture. 8

Figure 2. Subsequent Inter-PLMN Inter-MSC handover to MSC-C 11

Figure 3. Inter-PLMN handover agreement between three PLMNs 13

Figure 4. Inter-PLMN handover restrictions for subscribers 14

Figure 5. Usability of Inter-PLMN handover in Nokia Siemens Networks's DXMSCs. 16

Figure 6. Usability of Inter-PLMN handover in MSC vs BSC CGI format support. 16

Figure 7. Usability of Inter-PLMN handover in Nokia Siemens Networks's DX MSCsvs other vendor's MSCs. 17



List of figures



1 Feature description

1.1 Introduction

Inter-PLMN handover support enables handovers between networks(PLMNs). Multiple PLMN support in one MSC makes it possible to haveseveral PLMNs under one MSC area of coverage. This functionality differsfrom the normal handover procedure due to the fact that the MobileNetwork Codes (MNC) and possible Mobile Country Codes (MCC) of thetarget and source cell are different.

The following figure shows a typical environment:



Feature description

Figure 1. Multiple PLMN architecture.

1.2 Benefits for the operator

In essence, this feature provides a larger coverage area, faster networkrollout and potentially also improves profitability.

PLMN 1

LAC 1

PLMN 2LAC 4

PLMN 1LAC 2

PLMN 2LAC 3

MSC 1

MSC 2

Primary PLMNPLMN 1LAC 1

PLMN 2LAC 4

PLMN 1LAC 2

PLMN 2LAC 3

MSC 1

MSC 2

(MCC1, MNC1)



1.3 Requirements for using the feature

1.3.1 Software

This feature has no special requirements for software.

1.3.2 Hardware

This feature has no special requirements for hardware.

1.3.3 Products

This feature functions in the DX MSC and Compact DX MSC products.

1.4 Functionality

1.4.1 General

At the beginning of the handover, the MSC receives information from theBSC about the target cell identity for the handover. This identity is includedin the HANDOVER_REQUIRED message.

The target cell identity can be included in two formats:

1. MCC, MNC, LAC, CI (that is, CGI)

2. LAC, CI

The MSC also uses this information in order to control and continue thehandover procedure towards the target MSC.

Therefore, it is important that the MSC can handle the cell ID in bothformats.

1.4.2 Control of normal and subsequent Inter-PLMN handover

Handovers can take place from one PLMN to another if certain basicrequirements are fulfilled, such as neighbour cell definitions in eachPLMNs' radio access network. The MSCs should also know the addressesand target location area identities of the neighbour MSCs. Providing that



Feature description

these basic requirements are effective in the PLMNs, the operators havean Inter-PLMN handover agreement. This feature provides a way ofcontrolling to which PLMNs the Inter-PLMN Inter-MSC handover isallowed for a particular group of subscribers. A group of subscribers isidentified by the MCC-MNC and, optionally, by a part of the MSIN of thesubscriber's IMSI. Typically, all the subscribers of a particular PLMN areconsidered as one group of subscribers, thus the analysis of only MCC-MNC is enough in most cases.

The Inter-PLMN handover is controlled by all the MSCs participating in theInter-PLMN handover. Each MSC taking part in the Inter-PLMN handoverplays one of the following roles: relay MSC, new relay MSC, or anchorMSC. The Nokia Siemens Networks DX MSC supports Inter-PLMNhandover control while the Nokia Siemens Networks DX MSC plays any ofthe roles mentioned to guarantee that the Inter-PLMN handover can alsobe controlled in case some of the MSCs do not support the Inter-PLMNhandover control (multivendor case). The figure below illustrates anexample handover scenario in which the role of each MSC is shown.



Figure 2. Subsequent Inter-PLMN Inter-MSC handover to MSC-C

The call is established in the MSC1 (Anchor). At the call setup phase, theMSC1 receives the handover agreement list from the VLR for thesubscriber with IMSI1. When the Inter-PLMN Inter-MSC handover isattempted to MSC2 (relay MSC), the MSC2 asks the VLR for the handoveragreement list of that subscriber. The same happens for the subsequenthandover to MSC-C (new relay MSC).

MSC-A(anchor)PLMN1

MSC-B(relay)

MSC-C(new relay)

E-interface

moves

IMSI1 IMSI1

BSC/RNCPLMN2

BSC/RNCPLMN3

E-in

terfa

ce

E-interface

Handoversignalling

Before

handover

PSTN

After handover

Route of control and user plane

traffic before handover

Handover Signalling

Route of control and user plane

traffic after handover



Feature description

Note that the handover control is performed by each MSC in the sameway, irrespective of the PLMN in which the MSC is located. Note also thatall the MSCs are not necessarily in different PLMNs, but two or all of themcan be in the same PLMN.

The Inter-PLMN handover control uses a list of allowed PLMNs which theoperator(s) creates in the MSC. The list is called a handover agreement listand it is created separately for each subscriber group in the VLRdatabase. The VLR of each MSC involved in the handover finds out towhich subscriber group (for example, to which PLMN) a particular user -for whom the handover is attempted - belongs to, by analysing the MCC-MNC part (and optionally a part of MSIN) of the subscriber's IMSI. As aresult of the analysis, the VLR provides the MSC with the list.

If an operator wants to prevent the Inter-PLMN handover for any group ofsubscribers, the Handover Agreement list can be left empty.

The following example (see the figure below) illustrates a scenario in whichthere are Handover agreement list definitions in three PLMNs which haveInter-PLMN handover agreement between each other. The Inter-PLMNhandover has been explicitly allowed to the other two PLMNs in eachPLMN for all subscribers.



Figure 3. Inter-PLMN handover agreement between three PLMNs

Below is an example of a case in which one of the operators (Operator 2)wants to set some handover restrictions to particular subscriber groups.

PLMN 1

MSC1

PLMN 2 PLMN 3

MSC2 MSC3

OPERATOR 1 OPERATOR 2 OPERATOR 3

HO_agree list for IMSI1:

MCC1-MNC1, MCC2-MNC2, MCC3-MNC3











HO_agree list for IMSI1:MCC1-MNC1, MCC2-MNC2, MCC3-MNC3







Feature description

Operator 2 has a roaming agreement with PLMN X. However, Operator 2wants to prevent the Inter-PLMN handover for PLMN X subscribers toOperator 1 PLMN and allow Inter-PLMN handover to Operator 3 PLMN.This is achieved by Operator 2 by specifying the PLMN 2 and PLMN 3 intothe Handover Agreement list used for the PLMN X subscribers.

In the following example, a Handover Agreement exists between Operator1 and Operator 2, and between Operator 2 and Operator 3. There is noHandover Agreement between Operator 1 and Operator 3. However, sincean Inter-PLMN handover is technically possible from PLMN 2 to bothPLMN 1 and PLMN 3, and, if roaming is allowed, without explicitrestrictions the Inter-PLMN handover for subscriber's of Operator 1 toPLMN 3 is possible from the PLMN 2. The figure below illustrates howthese handovers can be prevented, and the type of Inter-PLMN handoversallowed for PLMN 1, 2, 3 subscribers with the necessary definitions inHandover Agreement lists.

Figure 4. Inter-PLMN handover restrictions for subscribers

PLMN 1

MSC1

PLMN 2 PLMN 3

MSC2 MSC3

OPERATOR 1 OPERATOR 2 OPERATOR 3

HO_agree list for IMSI1:MCC1-MNC1, MCC2-MNC2




HO_agree list for IMSI2:MCC1-MNC1, MCC2-MNC2, MCC3-MNC3



IMSI 1, IMSI 2

NOT allowed

IMSI 1, IMSI 2 IMSI 2, IMSI 3

IMSI 2, IMSI 3



Note

Inter-PLMN handover and subsequent handovers within the targetPLMN can be controlled even on the level of individual location areas, ifthe user is a national roaming subscriber. For further information, seeFeature 124, National roaming.

By means of equivalent PLMNs, the operator is able to upload a list ofPLMNs to users' mobile stations which the mobile stations will use toprioritise the PLMNs in the PLMN selection process. The operator canspecify the list for each subscriber group individually. For furtherinformation, see Feature 1260, Inter-system handover and UMTSchanges.

MSC support for Inter-PLMN handover

. When the target cell information is received from the BSC in CGIformat

The MNC and MCC of the target cell are included in the messageHANDOVER_REQUIRED from BSC.

In this case, it is possible to have same LAC definitions in different PLMNsunder different MSCs.

. When the target cell information is received from BSC in LAC+CIformat

The MNC and MCC of the target cell are NOT included in the messageHANDOVER_REQUIRED from the BSC. Therefore, the LAC in theneighbour cells of the involved PLMNs must be unique (that is, they musthave different values).

In the handover procedure, the LA information is checked in the locationarea data files. If both operators have the same LAC, this can lead to anerror situation.

This feature provides the operator with the means to add the MNC andMCC values into the location area data files in the neighbour MSCs of thePLMN. In this case, the source MSC can read these values from the fileand send them towards the target MSC in aMAP_PREPARE_HANDOVER message.



Feature description

Tariff change support for Inter-PLMN Inter-MSC handover

The PLMN operator can change the tariff when an Inter-PLMN handoveroccurs.

1.4.3 Feature usage requirements and limitations

Inter-PLMN Handover indication to MS

Inter-PLMN Handover indication to MS is not supported.

Usability of Inter-PLMN handover

Figure 5. Usability of Inter-PLMN handover in Nokia Siemens Networks's DXMSCs.

Figure 6. Usability of Inter-PLMN handover in MSC vs BSC CGI formatsupport.

NSN

MSC A(Anchor)

Inter-PLMNhandoverA ————> B(LACs NOT unique)

Inter-PLMNhandoverA <———— B(LACs NOT unique)

Inter-PLMNhandoverA ————> B(LACs unique)

Inter-PLMNhandoverA <———— B(LACs unique)

NSN

MSC B(Target)

a 1168YES

1168YES

Y Y Y Y

b 1168YES

1168NO

Y MAP ph2 used ->YMAP ph1 used ->N

Y Y

c 1168NO

1168NO

N N Y Y

NSNMSC A(Anchor)

1168YES

BSC A

CGI format (*)YES

Inter-PLMN handoverA ———> B

Y

1168YES

CGI format (*)NO

Y

1168NO

CGI format (*)YES

As in b, c in the table above

1168 CGI format (*) As in b, c in the table above



* neighbour cell definition and HANDOVER_REQUIRED from BSC in CGIformat.

Figure 7. Usability of Inter-PLMN handover in Nokia Siemens Networks's DXMSCs vs other vendor's MSCs.

1.4.4 Files

The radio network configuration files in the MSC have been updated tosupport different PLMN codes.

1.4.5 Parameters

The operator can activate or deactivate the feature using an activationparameter. The operator can set the values of the parameter with the WOAcommand of the Parameter Handling MML.

1.4.6 Statistics

The operator can use the following reports which support CGI format:

. MSC Observation report

. MSC Traffic Category Measurement report

. Handover report

. Handover observation report

. Threshold Alarms

NSN

MSC A(Anchor)

Inter-PLMNhandoverA ————> B(LACs NOT unique)

Inter-PLMNhandoverA <———— B(LACs NOT unique)

Inter-PLMNhandoverA ————> B(LACs unique)

Inter-PLMNhandoverA <———— B(LACs unique)

OTHER

MSC B(Target)

1168YES

X Y Y Y Y

1168NO

X N N Y Y



Feature description

1.4.7 Charging

The tariff of the call can be changed due to an Inter-PLMN Inter-MSChandover. The Mobile Country Code (MCC) and Mobile Network Code(MNC) information are available in mobile originating (MOC), mobileterminating (MTC), forwarding (FORW), supplementary services (SUPS)and unsuccessful call attempt (UCA) CDRs.

CDR generation in Inter-MSC handover

The Incoming Call Control Parameters File and Outgoing Call ControlParameters File contain, among others, the HOCDR (Handover TicketGeneration) MML parameter, which must be set if the POC and PTCCDRs should be generated when an Inter-MSC handover occurs.

The operator can change and/or interrogate the HOCDR MML parameterby means of the Call Control Parameters Handling MML.

HOCDR must be set if the POC and PTC CDRs should be generatedwhen Inter-MSC handover occurs in the source MSC.

The All-ticketing Parameter File (CHPARA) contains three parameterswhich indicate what tickets should be generated in a handover case.

These parameters should also be set to the correct values, and they are:

HO_PTC_CDR : PTC ticket generation in MSC-A

HO_POC_CDR : POC ticket generation in MSC-B

HO_MTC_CDR : MTC ticket generation in MSC-B.

Note

These parameters are not subscriber-specific.

Source MSC's information available in MSC B

As a new information for CDRs, the MSISDN number of the Source MSCcan be included in MTC CDR in the target MSC. A parameter in the sourceMSC defines the number that will be sent as the calling number to thetarget MSC. The calling number can be either the MSISDN number of thesource MSC or the MSISDN number of the subscriber. The operator canuse this parameter in order to define which number should be used.



Note

Source MSC information is in the national format and it should be set ifthe operator of the target MSC wants to keep a record of the subscriberroaming in the network.

1.5 Capacity

This feature has no significant effect on capacity.

1.6 Restrictions

Location dependant services

It is not possible to support Location dependant services, because theAnchor MSC does not have the necessary cell dependent information forthe use of location dependant services (this is true also for the normalInter-MSC handover).

Control of normal and subsequent Inter-PLMN handover

The list of the PLMNs to and from which the handover is allowed has amaximum of twenty entries.

1.7 Related and interworking features

. Feature 124, National roaming:

Inter-PLMN handover can be controlled and subsequent handoverswithin the target PLMN can be controlled even on the level ofindividual location areas, if the user is a nationally roamingsubscriber.

. Feature 1260, Inter-system handover and UMTS changes

This feature provides the Equivalent PLMN functionality whichenables the network to send instructions to mobile stations to whosePLMNs the MS should give a higher priority in the PLMN selection.



Feature description

AoC and Prepaid

When the new e-parameters are provided by Charging modificationanalysis, the AoC and prepaid based on the AoC are supported.

1.8 Compliance

. This feature is Nokia Siemens Networks-specific.

. This feature is supported in 3G.

1.9 Operator interfaces

1.9.1 MMLs

Network Location Area Address Handling MML

With this MML, the operator can update location area specific data in aneighbour MSC of the PLMN in LAI format.

The commands affected are:

EIA ADD LOCATION AREA TO NETWORK

EIR REMOVE LOCATION AREA FROM NETWORK

EIM MODIFY LOCATION AREA PARAMETERS

EIO OUTPUT NETWORK LOCATION AREA DATA

For more information, see Network Location Area Address Handling, EICommand Group.

Charging Modification Handling MML

With this MML, it is possible to create, modify, delete and interrogate thecharging modification and the result of the charging modification. Inaddition, the type of the charging modification can be changed and theattribute value based information can be added.

The commands affected are:



CMC CREATE CHARGING MODIFICATION

CMD DELETE CHARGING MODIFICATION

CMA ADD ATTRIBUTE VALUE BASED INFORMATION

CMM MODIFY CHARGING MODIFICATION

CMI INTERROGATE CHARGING MODIFICATION

For more information, see Charging Modification Handling, CM CommandGroup.

VLR and PLMN Parameter Handling MML

With this MML the operator can create, interrogate and delete a list ofPLMNs to which the Inter-PLMN handover is allowed for the subscriber.The list can contain a maximum of twenty different PLMNs.

The command affected is:

MXN MODIFY PLMN PARAMETERS

For more information, see VLR and PLMN Parameter Handling, MXCommand Group.

Note

Every time the MXN is used, the previous list is overwritten.

Traffic Category Object List Handling MML

New categories which affect the following commands:

TRC ADD OBJECTS TO OBJECT LIST

TRD REMOVE OBJECTS FROM OBJECT LIST

TRI INTERROGATE OBJECTS FROM OBJECT LIST



Feature description

For more information, see Traffic Category Object List Handling, TRCommand Group.

Supervision of Disturbances MML

The command affected is:

TCQ Interrogate Three Threshold Measurement

When the measurement type is HOTOT, the execution printout includestwo new lines for the new handover types.

For more information, see Supervision of Disturbances, TC CommandGroup.

Parameters Handling MML

With the parameter ho_allowed_for_nat_roam., the operator candetermine whether the handovers of national roaming subscribers areallowed outside the national roaming area or not.

The operator can set the values of this parameter with the command WOCof Parameters Handling MML. The possible values are:

TRUE Handovers are allowed

FALSE Handovers are not allowed

Location Area Handling MML

With this MML, the operator can update location area specific data in theMSC of a PLMN in LAI format. The commands are:

ZELC CREATE LOCATION AREA

The MCC and/or MNC values cannot be changed. The default valueshould be 000 for both parameters, therefore these values cannot beentered by the operator (i.e. the MML does not accept 000 as valid valuesfor MCC and MNC).

ZELO OUTPUT LOCATION AREA

Base Transceiver Station Handling MML

With this MML, the operator can update cell-specific data in the MSC of aPLMN in CGI format. The commands are:



ZEPC CREATE BTS

The MCC/MNC values are checked when creating the cells.

ZEPB DEFINE BSC-BTS-LAC RELATIONS

This command MCC/MNC includes an updating mechanism to the CellData File.

Base Station Controller Handling in MSC MML

When the MCC and MNC values are added to the NLAFIL file, there canbe several LAC values with different MCC and/or MNC. The default valueshould be 000 for both parameters, therefore these values cannot beentered by the operator (for example, the MML does not accept 000 asvalid values for MCC and MNC). The commands are:

ZEDB OUTPUT INFORMATION ON BSSAP VERSION

This command shows BSSAP data and BSSAP relations to BSC and LACin NLAFIL. The MCC and MNC information is provided into every printedLA.

1.9.2 Alarms

The relevant alarms will support the CGI format.

1.10 Subscriber interfaces

This feature has no subscriber interfaces.



Feature description

1.11 External interfaces

1.11.1 Network elements

Mobile Services Switching Centre (MSC)

After this feature has been implemented, the MSC supports Inter-PLMNhandover and tariff change when the PLMN changes due to this type ofhandover.

Billing Centre (BC)

This feature affects the Billing Centre because of the new fields in mobileoriginating (MOC), mobile terminating (MTC), forwarding (FORW),supplementary services (SUPS) and unsuccessful call attempt (UCA)CDRs.

The mobile country code (MCC) and mobile network code (MNC) areincluded in the subscriber's location information in MOC, MTC, FORW,SUPS and UCA CDRs. The last exchange's ID type of number (TON) isadded to MOC, MTC and FORW CDRs.



2 Main changes in Feature 1168: MultiplePLMN and Inter-PLMN Handover Support

2.1 Changes in the feature

This feature is implemented in M11.

2.1.1 Changes in the document

Changes made between issues 2-1 and 2-0

The title of the document has been corrected according to the approvedfeature name.

Changes made between issues 2-0 and 1-4

The company and product names have been changed according to theofficial Nokia Siemens Networks portfolio naming.



Main changes in Feature 1168: Multiple PLMN and Inter-PLMNHandover Support

FN1168 Multiple PLMN and Inter-PLMN Handover Support

Documents

nokia siemens networks

user plane traffic

plmn handover indication

multiple plmn architecture

handover agreement list

plmn handover support

mnc3 ho agree list

target cell identity