Enhanced token delivery scheme for reliable multicasting in wireless networks

When a mobile host moves from a base station to another, the old base station may pre-forward data to neighboring base stations to avoid transmission delay. However, if other mobile hosts move at short intervals, the old base station may retransmit the same data to the same neighboring base stations. Also, the old base station should retransmit data if the new base station has already discarded data even if the new base station is a member of the multicast group. We propose the Information Exchange Scheme (IES) for resolving the above problems. In the scheme, each base station indirectly exchanges the data delivery information with other base stations in the same multicast group for efficient and reliable multicast, and pre-forwards data not retransmitting the same data when a mobile host moves. We also show how IES is efficient by analysis and simulation.