E.1 GAN A/Gb Mode Specific Requirements for Interworking with UTRAN

3GPP44.318Generic Access Network (GAN)Mobile GAN interface layer 3 specificationRelease 17TS

The UE shall include the Support of Handover to GAN indication in the UE Radio Access Capabilities provided to the RNC.

NOTE: The RNC support of functionality for UTRAN to GAN Handover is implied by the inclusion of the ARFCN for GAN in the neighbour cell list of the UE.

The GAN and GERAN capable UE shall conform to all the requirements for Inter-RAT events as defined in TS 25.331 for reporting GERAN cells.

W.r.t. reporting GAN cells, the UE can be in one of two modes:

GAN preferred: the UE prefers to stay in GAN rather than GERAN or UTRAN.

GERAN/UTRAN preferred: the UE prefers to stay in GERAN/UTRAN rather than GAN;

Reporting of GAN cells is only performed with event 3A; GAN cells are never reported by events 3B, 3C, 3D or periodic reporting.

The GAN capable UE shall conform to all the requirements for Inter-RAT measurement reporting as defined in TS 25.331 for reporting of GAN cells, except when stated below:

– For the reporting of a GAN cell in case of configured event 3A, the UE shall act on the information originally received in the Measurement Control message as follows:

– Treat the value of the "Hysteresis" parameter as 0.

– Ignore the "Threshold other system" parameter.

– Treat the value of the "Time to trigger" parameter as 0ms.

– When the UE is in GAN preferred mode and an event 3A has been configured, the UE shall in addition act on the information originally received in the Measurement Control message, as follows:

– Treat the value of the "Threshold own system" parameter as 0.

As a result, the UE can report a GAN cell whenever it has successfully registered on a GANC;

– When the UE is in GERAN/UTRAN preferred mode and an event 3A has been configured, the UE shall only send a measurement about the GAN cell to trigger handover when no GERAN cells from the Inter-RAT measurement object list satisfy the triggering condition of the configured Event (as described in TS 25.331).

– When the UE is in GAN preferred mode and an event 3A has been configured, the UE may send a measurement about the GAN cell to trigger handover immediately following successful registration on the GANC.

– When the UE is sending an event 3A related measurement report about a GAN cell in order to trigger handover, the UE shall report that the GAN cell has the best possible receiving level (i.e., GSM carrier RSSI = 63) and therefore complies with the "threshold other system" signalled in the information originally received in the Measurement Control message.

NOTE: If the UE is in GAN preferred mode and an event 3A has been configured, it does not need to make inter-RAT measurements prior to including GAN cell information in the Measurement Report message sent to the UTRAN to trigger handover to GAN.

– The UE shall not include GAN cells in other Inter-RAT measurement reporting than when triggered by event 3A.

– If an event 3A is configured only with Inter-RAT cells not within any of the GERAN bands supported by the UE (as specified by the IE "Inter-RAT measurements object list" and taking into account any restriction configured by the IE "cell for measurement") this event shall not be counted as an Inter-RAT reporting criterion with respect to the UE capability for the Inter-RAT measurement category.

– If the UE fails to complete the handover to GAN as requested by the Handover From UTRAN Command message (e.g. UE loses connection to GAN), it shall act as in the handover failure case specified in TS 25.331.

The selection of the RF channel number (ARFCN) used for the UTRAN to GAN handover procedure should not correspond to a channel from any frequency band defined in TS 45.005, to avoid UEs not requiring compressed mode for GSM measurements from unnecessarily powering up their GSM receivers.