Mobile IP support in ad hoc networks with wireless backbone

We propose new agent discovery and route discovery schemes to support Mobile IP (MIP) in ad hoc networks with a wireless backbone. The wireless backbone, consisting of stationary wireless routers (WRs) and Internet gateways (IGs), is a kind of wireless access network of an IP-based core network. For efficient agent discovery, backbone-limited broadcasting of agent advertisement (AA) and proxy-AA schemes are used, which reduces the network-wide broadcasting overhead caused by periodic AA and agent solicitation (AS) messages and also decentralizes the MIP processing overhead in IGs. In order to reduce delay and control overhead during route discovery for destinations in the Internet, destination address caching and proxy-route reply (RREP) schemes are used. Also, to select more stable routes consisting of radio links with WRs, a priority-based route request (RREQ) rebroadcast scheme is used during route discovery. The proposed schemes, utilizing favorable features of the wireless backbone, can reduce control overhead during agent discovery and route discovery, and efficiently support MIP in ad hoc networks.