Tree-Based Reliable Multicast in Combined Fixed/Mobile IP Networks

This paper proposes a solution to delivering multicast data reliably not only to/from fixed hosts but also to/from mobile hosts in combined fixed/mobile IP networks, particularly with regard to the per-source shortest path multicast routing protocol and remote subscription option in IETF mobile IP multicast standard. We propose exploiting tree-based error recovery, well-established concept for reliable multicast in fixed networks, where a hierarchical logical tree of a source and receivers is constructed over which the responsibility of error recovery is distributed. We introduce a new entity named ARMM (Agent for Reliable Mobile Multicast) located at each cell of wireless/mobile networks. Each ARMM participates in a logical tree as a parent of mobile hosts in the corresponding cell. It is responsible for retransmission and requesting for retransmission on behalf of the mobile hosts. With aid of ARMM, the proposed scheme features (1) adaptive reconstruction of logical trees due to host mobility, (2) retransmission to mobile hosts via optimal routes, (3) abstracting a group of mobile hosts into a single ARMM (and thus reducing logical tree maintenance overhead), (4) efficient use of wireless bandwidth for retransmission, and (5) low processing burden on mobile hosts themselves. The experimental results show that the proposed scheme provides higher scalability than a scheme applying a generalized tree-based reliable multicast in mobile environments.