MAC Layer Support for High Rate Video Multicast Applications in Wireless LANs

Compared with unicast, multicast over wireless LANs should handle varying channel conditions of multiple users. The existing application layer multicast error control schemes, such as automatic repeat request (ARQ), forward error correction (FEC), hybrid error correction (HEC) etc. are based on MAC layer broadcast which is unreliable. For high rate real-time video multicast these schemes have to work under strict delay constraints. However, they don't work well with high error rates or burst errors and suffer the feedback implosion problem. Motivated by these, we try to support these schemes using a MAC layer reliable multicast, called Simple Leader Based Protocol (SLBP). Both the theoretical analysis and simulation experiments show that SLBP can correct nearly all the errors for the leader receiver in the MAC layer and the error rate at the non-leader receivers also decreases due to the residual effect of MAC level retransmissions to the leader. SLBP also alleviates the burst error, mitigates the feedback implosion and supports the application layer multicast error control schemes to work better under strict delay constraints.