Modes of Operation
The original Release 6 GAN specification supported a 2G (A/Gb) connection from the GANC into the mobile core network (MSC/GSN). Today all commercial GAN dual-mode handset deployments are based on a 2G connection and all GAN enabled devices are dual-mode 2G/Wi-Fi. The specification, though, defined support for multimode handset operation. Therefore, 3G/2G/Wi-Fi handsets are supported in the standard. The first 3G/UMA devices were announced in the second half of 2008.
A typical UMA/GAN handset will have four modes of operation:
- GERAN-only: uses only cellular networks
- GERAN-preferred: uses cellular networks if available, otherwise the 802.11 radio
- GAN-preferred: uses a 802.11 connection if an access point is in range, otherwise the cellular network
- GAN-only: uses only the 802.11 connection
In all cases, the handset scans for GSM cells when it first turns on, to determine its location area. This allows the carrier to route the call to the nearest GANC, set the correct rate plan, and comply with existing roaming agreements.
At the end of 2007, the GAN specification was enhanced to support 3G (Iu) interfaces from the GANC to the mobile core network (MSC/GSN). This native 3G interface can be used for dual-mode handset as well as 3G femtocell service delivery. The GAN release 8 documentation describes these new capabilities.
Read more about this topic: Generic Access Network
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