8.1 Mechanism of Mode Selection in Multi-mode terminals

3GPP43.318Generic Access Network (GAN)Release 17Stage 2TS

A Generic Access capable terminal may support any IP access technology in addition to the GERAN and possibly UTRAN radio interfaces. The MS may be either in the GERAN/UTRAN/E-UTRAN mode or in GAN mode of operation.

The MS can be configured to operate in one of the above two modes at any given time. There may be preferred mode of operation that can be configured by the user, or by the operator through various mechanisms, e.g. device management.

On power up, the MS always starts in GERAN/UTRAN/E-UTRAN mode and executes the normal power-up sequence as specified in 3GPP TS 23.122 [4]. Following this, the MS may switch into GAN mode based on mode selection preference determined by user preferences or operator configuration.

The various preferences for the MS that are possible are as follows:

– GERAN/UTRAN/E-UTRAN-only:

– The MS RR entity remains in GERAN/UTRAN/E-UTRAN mode and does not switch to GAN mode.

– GERAN/UTRAN/E-UTRAN-preferred:

– The MS RR entity is in GERAN/UTRAN/E-UTRAN mode as long as there is a suitable GERAN, UTRAN or E-UTRAN cell available. If the MS cannot find a suitable GERAN, UTRAN or E-UTRAN cell to camp on, and MS has successfully registered with a GANC over the generic IP access network, then the MS switches to GAN mode. When the MS in GAN mode is able to find a suitable GERAN, UTRAN or E-UTRAN cell to camp on, or the MS has de-registered or loses connectivity with the GANC over the generic IP access network, the MS returns to GERAN/UTRAN/E-UTRAN mode.

– GAN-preferred:

– When the MS has successfully registered with the GAN over the generic IP access network, the MS switches to GAN mode and stays in this mode as long as the GAN is available. When the MS deregisters, or otherwise loses connectivity with the GAN over the generic IP access network, the MS switches to GERAN/UTRAN/E-UTRAN mode.

– GAN-only:

– The MS switches to GAN mode (after initial power up sequence in GERAN/UTRAN/E-UTRAN mode to obtain cellular network information, but excluding (G)MM procedures with the core network) and does not switch to GERAN/UTRAN/E-UTRAN mode. During the initial power up sequence in GERAN/UTRAN/E-UTRAN mode the MS shall ignore paging message received through GERAN/UTRAN/E-UTRAN network.