3.4.4b Handover to CDMA2000 procedure

3GPP44.018GSM/EDGE Radio Resource Control (RRC) protocolMobile radio interface Layer 3 specificationRelease 16TS

Only valid for a CDMA2000 capable MS. In dedicated mode or dual transfer mode, a change to CDMA2000 channel(s) can be requested by the network RR sublayer. This change is performed through the handover to CDMA2000 procedure.

NOTE: The decision to do a handover to CDMA2000 and the choice of the new cell is out of the scope of this technical specification.

The handover to CDMA2000 procedure includes:

– The suspension of normal operation except for RR management (layer 3);

– The disconnection of the main signalling link, and of the other links via local end release (layer 2), and the disconnection of the TCH(s) if any;

– The disconnection and the deactivation of previously assigned channels and their release (layer 1);

– The abortion of the packet resources (see 3GPP TS 44.060), if in class A mode of operation;

– The establishment of CDMA2000 channel(s), see TIA/EIA/IS-833 and TIA/EIA/IS-2000-5-A.

The handover to CDMA2000 procedure is always initiated by the network.

3.4.4b.1 Handover to CDMA2000 initiation

The network initiates the handover to CDMA2000 procedure by sending an INTER SYSTEM TO CDMA2000 HANDOVER COMMAND message to the mobile station on the main DCCH. It then starts timer T3123.

If the INTER SYSTEM TO CDMA2000 HANDOVER COMMAND refers to a not known base station (see TIA/EIA/IS-98-D), this shall not be considered as an error.

When sending this message on the network side, and when receiving it on the mobile station side, all transmission of signalling layer messages except for those RR messages needed for this procedure and for abnormal cases, is suspended until resuming is indicated. These RR messages can be deduced from sub-clause 3.4.3 and 8.5.1 "Radio Resource management".

Upon receipt of the INTER SYSTEM TO CDMA2000 HANDOVER COMMAND message, the mobile station initiates, as described in sub-clause 3.1.4, the release of link layer connections and disconnects the physical channels (including the packet resources, if in class A mode of operation). Switching to the assigned base stations and physical channel establishment is described in TIA/EIA/IS-2000-5-A.

3.4.4b.2 Handover to CDMA2000 completion

NOTE: After lower layer connections are successfully established, the mobile station returns a Handoff Completion Message on CDMA2000 channels(s), see TIA/EIA/IS-833.

When receiving the Handoff Completion Message (TIA/EIA/IS-833), the network stops timer T3123 and releases the old channels.

3.4.4b.3 Abnormal cases

If the INTER SYSTEM TO CDMA2000 HANDOVER COMMAND message instructs the mobile station to use a frequency that it is not capable of, then the mobile station shall return a HANDOVER FAILURE message with cause "frequency not implemented", and the mobile station shall remain on the current channel(s).

If connection is not possible on the CDMA2000 channel(s) (see TIA/EIA/IS-2000-5-A), the MS reactivates the old channels, reconnects TCHs and triggers the establishment of the main signalling link. It then sends a HANDOVER FAILURE message on the main signalling link and resumes normal operation.

When the HANDOVER FAILURE message has been received, the network releases the CDMA2000 channel(s) if they were dedicated channels and stops timer T3123.

If a lower layer failure happens while attempting to connect back to the old channels, the standard rules are applied (cf. sub-clause 3.4.13.2 for dedicated mode).

On the network side, if timer T3123 elapses before either the Handoff Completion Message (TIA/EIA/IS-833) is received on the CDMA2000 channel(s), or a HANDOVER FAILURE message is received on the old channels, or the mobile station has re-established the call, the old channels are released if they were dedicated channels and all contexts related to the connections with that mobile station are cleared.

On the network side, lower layer failures occurring on the old channels after the sending of the INTER SYSTEM TO CDMA2000 HANDOVER COMMAND message are ignored.

3.4.4c Intermode handover to GERAN Iu mode procedure

3.4.4c.1 General

This sub-clause is only valid for a GERAN Iu mode capable MS. In dedicated mode or dual transfer mode, a change to GERAN Iu mode channel(s) can be requested by the network RR sublayer. This change is performed through the intermode handover to GERAN Iu procedure.

NOTE: The decision to do a handover to GERAN Iu mode and the choice of the new cell is out of the scope of this technical specification.

The handover to GERAN Iu mode procedure includes:

– The suspension of normal operation except for RR management (layer 3);

– The disconnection of the main signalling link, and of the other links via local end release (layer 2), and the disconnection of the TCH(s) if any;

– The disconnection and the deactivation of previously assigned channels and their release (layer 1);

– The abortion of the packet resources (see 3GPP TS 44.060), if in class A mode of operation;

– The establishment of the channel(s) in GERAN Iu mode, see 3GPP TS 44.118.

3.4.4c.2 Initiation of the handover to GERAN Iu mode procedure

The network initiates the handover to GERAN Iu mode procedure by sending an HANDOVER TO GERAN Iu MODE COMMAND message to the mobile station on the main DCCH. It then starts timer T3121.

If the HANDOVER TO GERAN Iu MODE COMMAND message refers to a not known cell (see 3GPP TS 45.008), this shall not be considered as an error.

When sending this message on the network side, and when receiving it on the mobile station side, all transmission of signalling layer messages except for those RR messages needed for this procedure and for abnormal cases, is suspended until resumption is indicated. These RR messages can be deduced from sub-clause 3.4.3 and sub-clause 8.5.1.

Upon receipt of the HANDOVER TO GERAN Iu MODE COMMAND message, the mobile station initiates, as described in sub-clause 3.1.4, the release of link layer connections and disconnects the physical channels (including the packet resources, if in class A mode of operation). Switching to the assigned cell(s) and physical channel establishement is described in 3GPP TS 44.118.

3.4.4c.3 Completion of the Handover to GERAN Iu Mode procedure

NOTE: After lower layer connections are successfully established, the mobile station returns a RADIO BEARER RECONFIGURATION COMPLETE message on GERAN Iu mode, see 3GPP TS 44.118.

When receiving the RADIO BEARER RECONFIGURATION COMPLETE message (3GPP TS 44.118), the network stops timer T3121 and releases the old channels.

3.4.4c.4 Abnormal cases

If the intermode HANDOVER TO GERAN Iu MODE COMMAND message instructs the mobile station to use a frequency that it is not capable of, then the mobile station shall stay on the current channel(s) and return a HANDOVER FAILURE message with cause "frequency not implemented".

If connection is not possible on the channel(s) in GERAN Iu mode (see 3GPP TS 44.118), the MS reactivates the old channel(s) and reconnects TCHs and triggers the establishment of the main signalling link. It then sends a HANDOVER FAILURE message on the main signalling link and resumes normal operation.

When the HANDOVER FAILURE message has been received, the network releases the new channel(s) if they were dedicated channels and stops timer T3121.

If a lower layer failure happens while attempting to connect back to the old channels, the standard rules are applied (cf. sub-clause 3.4.13.2 for dedicated mode).

On the network side, if timer T3121 expires, the old channels are released if they were dedicated channels and all contexts related to the connections with that mobile station are cleared.

On the network side, lower layer failures occurring on the old channels after the sending of the HANDOVER TO GERAN Iu MODE COMMAND message are ignored.