IEEE 802.21 Unifier
Standardizes session handover among IEEE802-based networks.
Enable client device to automatically choose the best available radio
network.
Seamlessly handover among networks during roaming without user
involvement.
Two primary types of information to be exchanged between
Layer-2 (IEEE 802-based networks) to mobile IP or other
Layer-3 roaming protocols are
Network detection and selection: mobile terminal must be able to
identify the type of available networks, authentication, cost. This
information can be provided by access points or base stations.
Layer 2 triggers Layer-3 with information about network conditions