An enhancement of multicast congestion control over hybrid wired/wireless networks
In wireless networks, random loss due to bit error leads to significant performance degradation to conventional multicast congestion control schemes. In this paper, we propose and study an enhanced multicast congestion control scheme, called EPGMCC (enhanced PGMCC), which achieves significant performance improvement over PGMCC over loss-prone wireless links. The key idea of EPGMCC is to discriminate random loss from congestion loss according to the measured network congestion level, and perform different actions accordingly. Specifically: 1) at the sender, it adapts the AIMD algorithms in TCP Veno (Cheng Peng Fu et al., 2003) to avoid the unnecessary window-halving induced by random loss and 2) at the receiver, a new scheme is designed to better measure the loss rate and thus help the sender to select the right representative of the group. Our extensive simulation results demonstrate that EPGMCC achieves significant throughput improvement over PGMCC in hybrid wired/wireless networks, furthermore, the improved throughput achieved by EPGMCC is not grabbed from the bandwidth of coexisting connections but from the utilization of available bandwidth that left unused. Throughput improvement of up to 40% can be demonstrated over typical wireless access link with 1% random loss rate.