IEEE 802.21

The IEEE 802.21 working group is developing a standard for handover between different wireless networks, between WLANs and mobile networks. These activities go under the title Media Independent Handover( MIH).

In addition to 802.11 WLANs and Bluetooth, the standard also includes cellularmobile communicationsnetworks such as GSM networks, General Packet Radio Service( GPRS) and UMTS networks, which use different handover mechanisms. This allows a user working with mobile computing, for example, to switch directly from a WLAN to a cellular network.

MIH concept with handover between different radio networks

In the 802.21 standard, a new function for access control to the lower two layers is implemented. This new function also includes new service access points( SAP) that can be queried by the higher layers. To provide the handover function, the standard must be implemented in the mobile devices and the network components. However, all devices and components remain backward compatible with the hardware that has not implemented Media Independent Handover (MIH).