Method and system for soft handoff of mobile terminals in IP wireless networks.

A method for providing soft handoff of a mobile terminal between different administrative domains in a wireless internet protocol (IP) network, said network including an IP backbone network having a multicast agent and an edge router, each administrative domain including a plurality of base stations and a multicast DHCP server, and said mobile terminal having a unique identifier and a plurality of unicast addresses, said method comprising the steps of

• the mobile terminal upon leaving a first administrative domain and entering a second administrative domain establishing unicast network connections with the plurality of base stations in the second administrative domain, each connection corresponding to a unicast address,
• the mobile terminal transmitting with its unique identifier an IP multicast address request to the multicast DHCP server in the second administrative domain,
• the multicast DHCP server in the second administrative domain determining the availability of a multicast address in the second administrative domain and assigning that multicast address to the mobile terminal, said multicast address being associated with the unicast addresses of the mobile terminal,
• generating in the multicast agent in the backbone network a unicast address table which associates the unique identifier for the mobile terminal with the assigned multicast address,
• the multicast agent forwarding the unique unicast address table to the edge router in the backbone network, and
• replacing in the edge router the mobile terminal unicast address with its corresponding multicast address from the address table.

A method for providing soft handoff of a mobile terminal between different administrative domains in a wireless internet protocol (IP) network, said network including an IP backbone network having a multicast agent and an edge router, each administrative domain including a plurality of base stations and a multicast DHCP server, and said mobile terminal having a unique identifier, said method comprising the steps of

• the mobile terminal upon leaving a first administrative domain and entering a second administrative domain establishing unicast network connections with the plurality of base stations in the second administrative domain, each connection corresponding to a unicast address,
• the mobile terminal transmitting with its unique identifier an IP multicast address request to the multicast DHCP server in the second administrative domain,
• the multicast server in the second administrative domain determining if a prior multicast address that had been assigned to the mobile terminal is available and, if so, assigning such prior multicast address to the mobile terminal, and
• generating in the multicast agent in the backbone network a unicast address table which associates the unique identifier for the mobile terminal with the assigned multicast address.

A method for providing soft handoff of a mobile terminal between different administrative domains in a wireless internet protocol (IP) network, said network including an IP backbone network having a multicast agent and an edge router, each administrative domain including a plurality of base stations and a multicast DHCP server, and said mobile terminal having a unique identifier, said method comprising the steps of

• the mobile terminal upon leaving a first administrative domain and entering a second administrative domain establishing unicast network connections with the plurality of base stations in the second administrative domain, each connection corresponding to a unicast address,
• the mobile terminal transmitting with its unique identifier an IP multicast address request to the multicast DHCP server in the second administrative domain,
• the multicast server in the second administrative domain determining if prior multicast addresses have been allocated to the mobile terminal,
• if a prior multicast address had been so allocated, determining if such prior multicast address is now available,
• if so available, assigning such prior multicast address to the mobile terminal, and
• generating in the multicast agent in the backbone network a unicast address table which associates the unique identifier for the mobile terminal with the assigned multicast address.