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

• US 6,611,510 B2
• Filed: 06/18/2001
• Issued: 08/26/2003
• Est. Priority Date: 06/18/2001
• Status: Expired due to Term

• Current Assignee: Telcordia Technologies Incorporated (Telefonaktiebolaget LM Ericsson)
• Original Assignee: Telcordia Technologies Incorporated (Telefonaktiebolaget LM Ericsson)
• Inventors: Famolari, David, Marples, David J.
• Primary Examiner(s): Nguyen, Steven
• Assistant Examiner(s): Molinari, Michael J
• Application Number:
  US09/883,569
• Publication Number:
  US 20020191567A1
• Time in Patent Office: 799 Days
• Field of Search: 370/335, 370/352, 370/312, 370/328, 370/331
• US Class Current: 370/335
• CPC Class Codes: H04L 12/1836 with heterogeneous network architecture
• CPC Class Codes: H04L 12/185 with management of multicast group membership
• CPC Class Codes: H04L 12/189 in combination with wireless systems selective distribution or broadcast in wireless communication networks H04W4/06
• CPC Class Codes: H04L 61/5014 using dynamic host configuration protocol [DHCP] or bootstrap protocol [BOOTP]
• CPC Class Codes: H04L 61/5069 for group communication, multicast communication or broadcast communication
• CPC Class Codes: H04W 36/0007 for multicast or broadcast services, e.g. MBMS multicast or broadcast application services H04W4/06; resource management for broadcast services H04W72/30; connection management for selective distribution or broadcast H04W76/40
• CPC Class Codes: H04W 36/0009 for a plurality of users or terminals, e.g. group communication or moving wireless networks user group management H04W4/08; processing of subscriber group data H04W8/186
• CPC Class Codes: H04W 36/0011 for data sessions of end-to-end connection
• CPC Class Codes: H04W 36/0019 adapted for mobile IP [MIP]
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 4/06 Selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS]; Services to user groups; One-way selective calling services
• CPC Class Codes: H04W 8/26 Network addressing or numbering for mobility support
• CPC Class Codes: H04W 80/04 Network layer protocols, e.g. mobile IP [Internet Protocol]

Abstract

A multicast address method for facilitating communication between nodes in “all IP” architectures that support CDMA soft handoff via IP multicasting wherein a multicast DHCP server allocates IP multicast addresses to mobile terminals from administratively scoped IP multicast addresses. IP multicast addresses are allocated to mobile terminals by offering, assigning, and distributing IP multicast addresses to the mobile terminals in response to IP multicast address requests from the mobile terminals to the multicast DHCP servers, which use unique mobile terminal identifiers to correlate mobile terminals with their prior and current IP multicast addresses. A multicast agent generates unicast IP address tables that map each of the unicast IP addresses, and edge routers use the unicast IP address tables to replace unicast IP addresses with their corresponding IP multicast address.

Claims

1. 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, and

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.

2. 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.

3. The method in accordance with claim 2 further comprising the edge router communicating information from the backbone network to the mobile terminal as multicast broadcast messages.

4. 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.

5. 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.

6. The method in accordance with claim 5 wherein the multicast DHCP server determines which IP multicast addresses are not in use and currently available in the second administrative domain if the DHCP server determines that there is no prior IP multicast address that had been allocated to the mobile terminal and which is currently available.

7. The method in accordance with claim 6 further comprising the steps of

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.

8. The method in accordance with claim 7 further comprising the edge router communicating information from the backbone network to the mobile terminal as multicast broadcast messages.