4.6 Inter-MSC Handover (UMTS to GSM)

29.0103GPPInformation element mapping between Mobile Station - Base Station System (MS - BSS) and Base Station System - Mobile-services Switching Centre (BSS - MSC)Release 17Signalling Procedures and the Mobile Application Part (MAP)TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

The general principles of the handover procedures are given in 3GPP TS 23.009 [2]. 3GPP TS 29.010 gives the necessary information for interworking between the 3GPP TS 25.413 [7] RANAP protocol, GSM handover procedures and the 3GPP TS 29.002 [9] MAP protocol. The RANAP protocol is used between the RNS and the 3G-MSC.

The following three principles apply for the Inter-MSC handover UMTS to GSM:

The BSSMAP parameters required for Inter-MSC handover UMTS to GSM are generated as in GSM.

Received BSSMAP parameters, e.g. cause code or Handover command, are mapped to the appropriate RANAP parameters, e.g. cause code transparent container to source RNS.

When new parameters need to be added for transfer on the E-interface, the principles stated in the beginning of clause 4.5 shall be followed.

4.6.1 Basic Inter-MSC Handover

When a Mobile Station is handed over between two MSCs, the establishment of a connection between them (described in 3GPP TS 23.009 [2]) requires interworking between A-Interface and E-Interface.

The signalling at initiation, execution, completion of the Basic Inter-MSC handover procedure is shown in figures 21 to 26 with both possible positive or negative outcomes.

Additionally figure 21b shows the possible interworking when the trace related message is transparently transferred on the E-Interface at Basic Inter-MSC Handover initiation.

RNS-A 3G-MSC-A MSC-B

| | |

|RELOCATION | |

|————–>|MAP PREPARE HANDOVER |

|REQUIRED |————————>| +—————-+

| | | +—————-+

| | |

| | | BSS-B

| | | |

| | |HANDOVER REQUEST |

| | |——————>|

Figure 21a: Signalling for Basic Inter-MSC Handover initiation (no trace related messages transferred)

RNS-A 3G-MSC-A MSC-B

| (*) |

|RELOCATION | |

|————–>|MAP PREPARE HANDOVER |

|REQUIRED |————————>| +—————-+

| | | +—————-+

| | |

| | | BSS-B

| | | |

| | |HANDOVER REQUEST |

| | |——————>|

| | | |

| | |MSC INVOKE TRACE |

| | |—————>(***)

Figure 21b: Signalling for Basic Inter-MSC Handover initiation (MSC invoke trace message transferred)

(*): Tracing invocation has been received from VLR.

(**): In that case, HANDOVER REQUEST and MSC INVOKE TRACE messages are included within the AN-APDU parameter.

(***): MSC INVOKE TRACE is forwarded to BSS-B if supported by MSC-B.

Possible Positive outcomes:

a) successful radio resources allocation and handover number allocation (if performed):

RNS-A 3G-MSC-A MSC-B BSS-B

| | | |

| | |HANDOVER REQUEST |

| | |<——————|

| | |ACKNOWLEDGE |

| | MAP PREPARE HANDOVER | |

| |<————————| |

| | response | |

| | | |

|RELOCATION COMMAND | |

|<————–| | |

b) radio resources allocation queued and successful handover number allocation (if performed). Later successful radio resources allocation indication:

RNS-A 3G-MSC-A MSC-B BSS-B

| | | |

| | |QUEUING INDICATION |

| | |<——————|

| |MAP PREPARE HANDOVER | |

| |<————————| |

| | response | |

| | |HANDOVER REQUEST |

| | |<——————|

| | |ACKNOWLEDGE |

| |MAP PROCESS ACCESS | |

| |<————————|

| RELOCATION COMMAND SIGNALLING request | |

|<————–| | |

| | | |

Figure 22: Signalling for Basic Inter-MSC Handover execution (Positive outcomes)

Possible Negative outcomes:

c) user error detected, or handover number allocation unsuccessful (if performed), or component rejection or dialogue abortion performed by MSC-B:

RNS-A 3G-MSC-A MSC-B BSS-B

| | | |

| |MAP PREPARE HANDOVER response |

| |negative result, MAP CLOSE |

| |<————————| |

| |MAP U/P-ABORT | |

| | | |

|RELOCATION PREPARATION | |

|<————–| | |

|FAILURE(Note 1)| | |

| | | |

d) radio resources allocation failure:

RNS-A 3G-MSC-A MSC-B BSS-B

| | | |

| | |HANDOVER FAILURE |

| | |<——————|

| |MAP PREPARE HANDOVER | |

| |<————————| |

| | response | |

| | | |

|RELOCATION PREPARATION | |

|<————–| | |

|FAILURE(Note 1)| | |

| | | |

e) radio resources allocation queued and successful handover number allocation (if performed). Later unsuccessful radio resources allocation:

RNS-A 3G-MSC-A MSC-B BSS-B

| | | |

| | |QUEUING INDICATION |

| | |<——————|

| |MAP PREPARE HANDOVER | |

| |<————————| |

| | response | |

| | | |

| | |HANDOVER FAILURE |

| | |<——————|

| |MAP PROCESS ACCESS | |

| |<————————| |

| | SIGNALLING request | |

| | | |

|RELOCATION PREPARATION | |

|<————–| | |

|FAILURE(Note 1)| | |

f) unsuccessful handover execution (Reversion to the old radio resources):

RNS-A 3G-MSC-A MSC-B BSS-B

| | | |

|RELOCATION | | |

|————–>| | |

|CANCEL | | |

| |MAP U -ABORT | |

| |————————>| |

| | |CLEAR COMMAND |

| | |——————>|

|RELOCATION | | |

|<————–| | |

|CANCEL ACK | | |

Figure 23: Signalling for Basic Inter-MSC Handover execution (Negative outcomes)

NOTE 1: Possible rejection of the handover because of the negative outcome of MAP or RANAP procedure.

RNS-A 3G-MSC-A MSC-B BSS-B

| | | |

| | |HANDOVER COMPLETE |

| | |<——————|

| |MAP SEND END SIGNAL request |

| |<————————| |

|IU RELEASE COMMAND | |

|<————–| | |

| | | |

Figure 24: Signalling for Basic Inter-MSC Handover completion

Positive outcome:

RNS-A 3G-MSC-A MSC-B BSS-B

| | | |

| |MAP SEND END SIGNAL | |

| |————————>| |

| | response |CLEAR COMMAND |

| | |——————>|

| | | (Note 2) |

Figure 25: Signalling for Basic Inter-MSC Handover completion (Positive outcome)

Negative outcome:

RNS-A 3G-MSC-A MSC-B BSS-B

| | | |

| | MAP U/P -ABORT | |

| |————————>| |

| | |CLEAR COMMAND |

| | |——————>|

| | | |

Figure 26: Signalling for Basic Inter-MSC Handover completion (Negative outcome)

NOTE 2: From interworking between MAP and BSSMAP point of view, when the call is released.

The handover procedure is normally triggered by RNS-A by sending a RELOCATION REQUIRED message on Iu-Interface to 3G-MSC-A. The invocation of the Basic Inter-MSC handover procedure is performed and controlled by 3G-MSC-A. The sending of the MAP Prepare-Handover request to MSC-B is triggered in 3G-MSC-A upon receipt of the RELOCATION REQUIRED message. For compatibility reason, the cell identity of the cell where the call is to be handed over in MSC-B area, provided in the RELOCATION REQUIRED message, is mapped into targetCellId MAP parameter and the HANDOVER REQUEST message is encapsulated in the AN-APDU MAP parameter of the Prepare‑Handover MAP request. MSC-B can invoke another operation towards the VLR-B (allocation of the handover number described in 3GPP TS 29.002 [9]).

Additionally, if tracing activity has been invoked, the trace related message can be transferred on the E-Interface encapsulated in the AN-APDU MAP parameter of the Prepare-Handover Request. If transferred, one complete trace related message at a time shall be included in the AN-APDU MAP parameter after the HANDOVER REQUEST message.

The interworking between Prepare Handover and RELOCATION REQUIRED is as follows:

—————————————————————-

| 25.413 29.002 |Notes

——–┼————————————————-┼—–

Forward | RELOCATION REQUIRED MAP PREPARE HANDOVER request|

message | |

| -ho-NumberNotRequired| 1

| RANAP information -targetCellId |

| elements -AN-APDU( | 2

| HANDOVER REQUEST, |

| |

| MSC INVOKE TRACE) |

——–┼————————————————-┼—–

Positive| RELOCATION CMD MAP PREPARE HANDOVER response|

result | | 3

| -handover number |

| -AN-APDU( |

| QUEUING INDICATION |

| or HANDOVER REQUEST|

| ACKNOWLEDGE) |

| |

——–┼————————————————-┼—–

Negative| RELOCATION PREP FAILURE MAP PREPARE HANDOVER| 4

result | |

| Relocation failure in System Failure |

| target RNC/CN or target system |

|" No Handover Number |

| available |

|" UnexpectedDataValue|

|" Data Missing |

| |

|" MAP CLOSE |

|" MAP U/P -ABORT |

| |

NOTE 1: The BSSMAP information elements are already stored in 3G-MSC.

The ho-NumberNotRequired parameter is included by 3G-MSC-A, when 3G-MSC-A decides not to use any circuit connection with MSC-B. No handover number shall be present in the positive result. Any negative response from MSC-B shall not be due to handover number allocation problem.

NOTE 2: The process performed on the RANAP information elements received in the RELOCATION REQUIRED message is described in the 3GPP TS 25.413 [7].

NOTE 3: The response to the Prepare-Handover request can include in its AN-APDU parameter, identifying the 3GPP TS 48.006 protocol, either a BSSMAP QUEUING INDICATION, or a BSSMAP HANDOVER REQUEST ACKNOWLEDGE.

In the first case, 3G-MSC-A shall wait for the radio resources allocation response from MSC-B, transmitted to 3G-MSC-A as described in clause 4.5.4.

In the second case, the positive result triggers in 3G-MSC-A the sending on Iu-Interface of the RELOCATION CMD.

In the third case, the positive result triggers in 3G-MSC-A.

NOTE 4: The possible sending of the RELOCATION PREP FAILURE message is described in the 3G 25.413.

(The possible sending of the RELOCATION PREP FAILURE message upon receipt of the HANDOVER FAILURE is out of the scope of the 3GPP TS 29.010 and lies in the 3GPP TS 25.413 [7]).

The interworking between Send End Signal and HANDOVER COMPLETE in MSC-B is as follows:

—————————————————————-

| 48.008 29.002 |Notes

——–┼————————————————-┼—–

Forward | HANDOVER COMPLETE MAP SEND END SIGNAL request |

message | |

| -AN-APDU( |

| HANDOVER COMPLETE)|

| |

——–┼————————————————-┼—–

Positive| CLEAR COMMAND MAP SEND END SIGNAL response|

result | -Call Control release | 1

——–┼————————————————-┼—–

Negative| CLEAR COMMAND |

result | -Call Control release MAP CLOSE | 2

| -Call Control release MAP U/P -ABORT |

| |

NOTE 1: The positive empty result triggers the clearing of the Radio Resources on the A-Interface and the release of the SCCP connection between MSC-B and BSS-B. If a circuit connection is used between 3G_MSC-A and MSC-B, the ‘Call Control release’ clearing cause shall only be given to BSS-B when MSC-B has received a clearing indication on its circuit connection with 3G_MSC-A.

NOTE 2: The abortion of the dialogue or the rejection of the component triggers in MSC-B the clearing of its circuit connection with 3G_MSC-A, if any, of the Radio Resources on the A-Interface and the release of the SCCP connection between MSC-B and BSS-B.

The interworking between Send End Signal and IU RELEASE COMMAND in 3G_MSC-A is as follows:

—————————————————————-

| 29.002 25.413 |Notes

——–┼————————————————-┼—–

Forward | MAP SEND END SIGNAL IU RELEASE COMMAND |

message | response |

| -AN-APDU(HANDOVER COMPLETE) |

| Successful Relocation |

——–┼————————————————-┼—–

Positive| |

result | |

——–┼————————————————-┼—–

Negative| |

result | |

The interworking between RELOCATION CANCEL in case of reversion to old channel of the UE and User Abort in 3G-MSC-A is as follows:

—————————————————————-

| 25.413 29.002 |Notes

——–┼————————————————-┼—–

Forward | RELOCATION CANCEL MAP U -ABORT |

message | |

| -Relocation cancelled |

——–┼————————————————-┼—–

Positive| RELOCATION CANCEL ACKNOWLEDGEMENT |

result | |

——–┼————————————————-┼—–

Negative| |

result | |

4.6.2 Subsequent Inter-MSC Handover from 3G-MSC-B back to MSC-A

When a Mobile Station is being handed over back to MSC-A, the procedure (described in TS 23.009) requires interworking between A-Interface, Iu-interface and E-Interface.

The signalling at initiation, execution and completion of the Subsequent Inter-MSC handover procedure is shown in figures 27 to 31.

RNS-A 3G-MSC-B MSC-A

| | |

|RELOCATION | |

|————–>|MAP PREPARE SUBSEQUENT |

|REQUIRED |————————>|

| |HANDOVER request |

| | | BSS-B

| | | |

| | |HANDOVER REQUEST |

| | |——————>|

Figure 27: Signalling for Subsequent Inter-MSC Handover back to MSC-A initiation

Possible Positive outcomes:

a) successful radio resources allocation:

RNS-A 3G-MSC-B MSC-A BSS-B

| | | |

| | |HANDOVER REQUEST |

| | |<——————|

| | |ACKNOWLEDGE |

| | MAP PREPARE SUBSEQUENT | |

| |<————————| |

| | HANDOVER response | |

|RELOCATION CMD | | |

|<————–| | |

b) radio resources allocation queued. Later successful radio resources allocation indication:

RNS-A 3G-MSC-B MSC-A BSS-B

| | |QUEUING INDICATION |

| | |<——————|

| | MAP PREPARE SUBSEQUENT | |

| |<————————| |

| | HANDOVER response | |

| | |HANDOVER REQUEST |

| | |<——————|

| | |ACKNOWLEDGE |

| | MAP FORWARD ACCESS | |

| |<————————| |

| | SIGNALLING request | |

|RELOCATION CMD | | |

|<————–| | |

Figure 28: Signalling for Subsequent Inter-MSC Handover back to MSC-A execution (Positive outcome)

Possible Negative outcomes:

c) user error detected, or component rejection or dialogue abortion performed by MSC-A:

RNS-A 3G-MSC-B MSC-A BSS-B

| |MAP PREPARE SUBSEQUENT HANDOVER |

| |<————————| |

|RELOCATION PREP| response negative result| |

|<————–| | |

|FAILURE(Note 1)| | |

| | | |

d) component rejection or dialogue abortion performed by MSC-A:

RNS-A 3G-MSC-B MSC-A BSS-B

| |MAP CLOSE, MAP U/P ABORT | |

| |<————————| |

|IU RELEASE | | |

|<————–| | |

| COMMAND | | |

e) radio resources allocation failure:

RNS-A 3G-MSC-B MSC-A BSS-B

| | | HANDOVER FAILURE |

| | |<——————|

| |MAP PREPARE SUBSEQUENT | |

| |<————————| |

|RELOCATION PREP| HANDOVER response | |

|<————–| | |

|FAILURE(Note 1)| | |

f) radio resources allocation queued. Later unsuccessful radio resources allocation:

RNS-A 3G-MSC-B MSC-A BSS-B

| | |QUEUING INDICATION |

| | |<——————|

| | MAP PREPARE SUBSEQUENT | |

| |<————————| |

| | HANDOVER response | |

| | |HANDOVER FAILURE |

| | |<——————|

| | MAP FORWARD ACCESS | |

| |<————————| |

|RELOCATION PREP| SIGNALLING request | |

|<————–| | |

|FAILURE(Note 1)| | |

Figure 29: Signalling for Subsequent Inter-MSC Handover back to MSC-A execution
(Negative outcome)

NOTE 1: Possible rejection of the handover because of the negative outcome of MAP or BSSMAP procedure.

BSS-B MSC-A 3G-MSC-B RNS-A

| | | |

|HANDOVER | | |

|————–>|MAP SEND END SIGNAL | |

|COMPLETE |————————>| |

| | response | |

| | |Iu RELEASE COMMAND |

| | |——————>|

Figure 30: Signalling for Subsequent Inter-MSC Handover back to MSC-A completion
(Successful completion of the procedure)

NOTE: Positive outcome case shown in figure 9.

BSS-B MSC-A 3G-MSC-B RNS-A

| | | |

|HANDOVER | | |

|————–>|MAP SEND END SIGNAL | |

|COMPLETE |————————>| |

| | response | |

| | | |

| |MAP U/P -ABORT | |

| |<————————| |

| | |Iu RELEASE COMMAND |

| | |——————>|

| | |(Note 1) |

Figure 31: Signalling for Subsequent Inter-MSC Handover back to MSC-A completion (Unsuccessful completion of the procedure)

NOTE 1: Abnormal end of the procedure which triggers the clearing of all resources in 3G-MSC-B.

The interworking between Prepare Subsequent Handover and RELOCATION REQUIRED is as follows:

—————————————————————-

| 25.413 29.002 |Notes

——–┼————————————————-┼—–

Forward |REL. REQUIRED MAP PREPARE SUBSEQUENT HANDOVER|

message | request |

| |

| -target MSC number |

| -targetCellId |

| -AN-APDU( |

| HANDOVER REQUEST) |

| |

| RANAP information BSSMAP information |

| elements: elements: |

| |

| MS Classmark 2 CM2 |

| Source Id Cell Id (serving) |

| Target Id Cell Id (target) |

| Cause Cause |1

| MS Classmark 3 CM3 |

| |

| info stored/generated |

| in/by 3G-MSC-B: |

| Message Type |

| Channel Type |

| Speech version |

| Priority |

| Interference Band |

| to be used |

| |

——–┼————————————————-┼—–

Positive|RELOCATION CMD. MAP PREPARE SUBSEQUENT HANDOVER|

result | response | 2

| -AN-APDU( |

| QUEUING INDICATION |

| or HANDOVER REQUEST|

| ACKNOWLEDGE or |

| HANDOVER FAILURE) |

| |

| RANAP information BSSMAP information |

| elements: elements: |

| L3 information L3 information |

| |

——–┼————————————————-┼—–

Negative| REL. PREP. FAILURE MAP PREPARE SUBSEQUENT| 3

result | HANDOVER response |

| Relocation Failure in Target CN/RNC or Target System Unknown MSC |

| Relocation Failure in Target CN/RNC or Target System Subsequent Handover |

| Failure |

| Relocation Failure in Target CN/RNC or Target System

| |

UnexpectedDataValue |

| Relocation Failure in Target CN/RNC or Target System Data Missing |

| |

| Iu RELEASE COMMAND |

| |

| Relocation Cancelled MAP CLOSE |

| Relocation Cancelled MAP U/P -ABORT |

| |

NOTE 1: The mapping of cause code values between BSSMAP and RANAP is FFS.

NOTE 2: The response to the Prepare-Subsequent-Handover request can include in its AN-APDU parameter, identifying the 3GPP TS 48.006 protocol, a BSSMAP QUEUING INDICATION, or a BSSMAP HANDOVER REQUEST ACKNOWLEDGE or a BSSMAP HANDOVER FAILURE.

In the first case, 3G-MSC-B shall wait for the radio resources allocation response from MSC-A, transmitted to 3G-MSC-B as described in clause 4.5.4.

In the second case, the positive result triggers in 3GMSC-B the sending on Iu‑Interface of the RELOCATION COMMAND.

In the third case, the positive result triggers in 3G-MSC-B the sending of the RELOCATION PREPARATION FAILURE.

NOTE 3: The possible sending of the RELOCATION PREPARATION FAILURE message is described in 3GPP TS 25.413 [7].

The interworking between Send End Signal Result and HANDOVER COMPLETE in MSC-A is as follows:

—————————————————————-

| 48.008 29.002 |Notes

——–┼————————————————-┼—–

Forward | HANDOVER COMPLETE MAP SEND END SIGNAL |

message | response |

| |

——–┼————————————————-┼—–

Positive| |

result | |

——–┼————————————————-┼—–

Negative| |

result | MAP U/P -ABORT | 1

| |

NOTE: The abortion of the dialogue ends the handover procedure with 3G-MSC-B.

4.6.3 Subsequent Inter-MSC Handover to third MSC

When a Mobile Station is being handed over to a third MSC, the procedure (described in 3GPP TS 23.009 [2]) does require one specific interworking case in MSC-A between E-Interface from 3G-MSC-B and E-Interface from MSC-B’ other than the combination of the ones described in clauses 4.6.1 and 4.6.2.

RNS-A 3G-MSC-B MSC-A MSC-B’

| | | |

|RELOCATION | | |

|———–>|MAP PREPARE SUBSEQUENT| |

|REQUIRED |———————>| |

| |HANDOVER request |MAP PREPARE |

| | |—————>|

| | |HANDOVER request|

| | | |+——-+

| | | ||Possib.|

| | | ||Alloc. |

| | | ||of ho. |

| | | ||number |

| | | || VLR-B |

| | | |+——-+

| | | | BSS-B’

| | | | |

| | | |——–>|

| | | |

Figure 32: Signalling for Subsequent Inter-MSC Handover to third MSC (MSC-B’) initiation

Possible Positive outcomes:

a) successful radio resources allocation:

RNS-A 3G-MSC-B MSC-A MSC-B’

| | | |

| | | | BSS-B’

| | | | |

| | | |<——–|

| | | ACKNOWLEDGE

| | | | |

| | |MAP PREPARE HANDOVER |

| | |<—————| |

| |<———————| | |

|<———–| | | |

| | | | |

b) radio resources allocation queued and successful handover number allocation, if performed. Later successful radio resources allocation indication:

RNS-A 3G-MSC-B MSC-A MSC-B’

| | | |

| | | | BSS-B’

| | | | |

| | | |<——–|

| | | | |

| | |MAP PREPARE HANDOVER |

| | |<—————| |

| |<———————| | |

| | | |<——–|

| | | ACKNOWLEDGE

| | | | |

| | |MAP PROCESS ACCESS |

| | |<—————| |

| |MAP FORWARD ACCESS |SIGNALLING request |

| |<———————| | |

|<———–| | | |

Figure 33: Signalling for Subsequent Inter-MSC Handover to third MSC (MSC-B’) execution
(Positive outcome)

Possible Negative outcomes:

c) user error detected, or component rejection or dialogue abortion performed by MSC-B’:

RNS-A 3G-MSC-B MSC-A MSC-B’

| | | |

| | | | BSS-B’

| | |MAP PREPARE HANDOVER |

| | |response negative result |

| | |<—————| |

| |<———————| | |

| |HANDOVER response negative | |

|<———–| | | |

d) radio resources allocation failure:

RNS-A 3G-MSC-B MSC-A MSC-B’

| | | |

| | | | BSS-B’

| | | | |

| | | |<——–|

| | | | |

| | |MAP PREPARE HANDOVER |

| | |<—————| |

| |<———————| | |

|<———–| | | |

e) radio resources allocation queued and successful handover number allocation (if performed). Later unsuccessful radio resources allocation:

RNS-A 3G-MSC-B MSC-A MSC-B’

| | | |

| | | | BSS-B’

| | | | |

| | | |<——–|

| | | | |

| | |MAP PREPARE HANDOVER |

| | |<—————| |

| |<———————| | |

| | | |<——–|

| | | | |

| | |MAP PROCESS ACCESS |

| | |<—————| |

| | |SIGNALLING request |

| |<———————| | |

|<———–| | | |

Figure 34: Signalling for Subsequent Inter-MSC Handover to third MSC (MSC-B’) execution (Negative outcome)

NOTE 1: Possible rejection of the handover because of the negative outcome of MAP or BSSMAP procedure.

Positive outcome:

RNS-A 3G-MSC-B MSC-A MSC-B’

| | | |

| | | | BSS-B’

| | | | |

| | | |<——–|

| | | | |

| | |MAP SEND END SIGNAL |

| | |<—————| |

| |<———————| | |

|<———–| | | |

Figure 35: Signalling for Subsequent Inter-MSC Handover to third MSC (MSC-B’) completion (Successful completion of the procedure)

Negative outcome:

RNS-A 3G-MSC-B MSC-A MSC-B’

| | | |

|RELOCATION | | | BSS-B’

|———–>| | | |

| |———————>| | |

| |SIGNALLING request (Note 1) | |

| | | | |

| | |—————>| |

| | | |——–>|

|<———–| | | |

| | | | |

Figure 36: Signalling for Subsequent Inter-MSC Handover to third MSC (MSC-B’) completion (Unsuccessful completion of the procedure)

NOTE 1: Specific interworking case detailed below.

The specific interworking case in MSC-A compared to the clauses 4.5.1 and 4.5.2 occurs between HANDOVER FAILURE encapsulated in a Process Access Signalling from 3G-MSC-B and the abortion of the dialogue with MSC-B’ in the case of a reversion to old channel of the MS:

—————————————————————-

| 29.002 29.002 |Notes

——–┼————————————————-┼—–

Forward | MAP PROCESS-SIGNALLING |

message | request |

| |

| -AN-APDU( MAP U -ABORT | 1

| HANDOVER FAILURE) |

| |

——–┼————————————————-┼—–

Positive| |

result | |

——–┼————————————————-┼—–

Negative| |

result | MAP U/P -ABORT | 2

| |

NOTE 1: The abortion of the dialogue triggers in MSC-B’ the clearing of the circuit connection with MSC-A, if any, and of the Resources between MSC-B’ and BSS-B’.The abortion of the dialogue ends the handover procedure with MSC-B’.

NOTE 2: The abortion of the dialogue ends the handover procedure with 3G-MSC-B.

4.6.4 BSSAP Messages transfer on E-Interface

The handling is described in clause 4.5.4.

4.6.5 Processing in MSC-B, and information transfer on E-interface

The handling is described in clause 4.5.5.

4.6.6 Cause Code Mapping

When a Mobile Station is handed over between UMTS and GSM, a mapping of the cause codes used in the RANAP and the BSSMAP protocols is needed. The mapping described here is applicable to the BSSMAP protocol even when used inside MAP in the E-interface.

The mapping between the cause codes received in RANAP Relocation Required and the cause codes sent in BSSMAP Handover Request is as follows:

—————————————————————-

25.413 48.008 |Notes

——————————————————-┼——–

RELOCATION REQUIRED HANDOVER REQUEST |

-Time critical relocation -‘uplink quality’ |

-Resource optimisation -Traffic |

relocation |

-Relocation desirable for -Better cell |

radio reasons |

-Directed retry -Directed retry |

-Reduce Load in -Reduce Load in |

serving cell serving cell |

-Any other value -Better cell |

The mapping between the cause codes received in RANAP Relocation Cancel and the cause codes sent in BSSMAP Clear Command is as follows:

—————————————————————-

25.413 48.008 |Notes

——————————————————-┼——–

RELOCATION CANCEL CLEAR COMMAND |

-Trelocprepexpiry -Radio interface |

failure, reversion to |

old channel |

-Interaction with other -Radio interface |

procedure failure, reversion to |

old channel |

-Any other value -Radio interface |

failure, reversion to |

old channel |

The mapping between the cause codes received in BSSMAP Handover Failure and the cause codes sent in RANAP Relocation Preparation Failure is as follows:

—————————————————————-

48.008 25.413 |Notes

——————————————————-┼——–

HANDOVER FAILURE RELOCATION PREP. FAILURE|

-Ciphering algorithm not -Requested ciphering |

supported and/or integrity |

protection is not |

supported |

-Circuit pool mismatch | 1

-Equipment failure -Relocation failure in |

Target CN/RNC or |

target system |

-Invalid message contents -Abstract Syntax Error |

-No radio resource available -No Radio Resources |

Available in Target |

Cell |

-O and M intervention -O and M intervention |

-Radio interface failure, | 2

reversion to old channel |

-Radio interface message -Relocation failure in |

failure Target CN/RNC or |

target system |

-Requested speech version -Relocation failure in |

unavailable Target CN/RNC or |

target system |

-Requested terrestrial -Relocation failure in |

resource unavailable Target CN/RNC or |

target system |

-Requested transcoding/rate -Relocation failure in |

adaption unavailable Target CN/RNC or |

target system |

-Switch circuit pool | 1

-Terrestrial circuit already -Relocation failure in |

allocated Target CN/RNC or |

target system |

-Traffic load in the target -Traffic load in the |

cell higher than in the -target cell higher |

source cell than in the source |

cell |

-Any other value -Relocation failure in |

Target CN/RNC or |

target system |

NOTE 1: Cause code not used at inter-system handover.

NOTE 2: Cause code not applicable to this traffic case.

The mapping between the cause codes received in BSSMAP Clear Request and the cause codes sent in RANAP Iu Release Request is as follows:

—————————————————————-

48.008 25.413 |Notes

——————————————————-┼——–

CLEAR REQUEST IU RELEASE REQUEST |

-Radio interface message -Relocation failure in |

failure Target CN/RNC or |

target system |

-O and M intervention -O and M intervention |

-Equipment failure -Relocation failure in |

Target CN/RNC or |

target system |

-Joined group call channel -Unspecified failure |

-Protocol failure between BSS -Message not compatible|

and MSC with receiver state |

-Preemption -RAB pre-empted |

-Access restricted due -Access restricted due |

to shared networks to shared networks |

-Any other value -Relocation failure in |

Target CN/RNC or |

target system |