Enhancing cellular multicast performance using ad hoc networks

Although multicast communication is well-suited to shared wireless links, receiver heterogeneity impedes the use of multicast in wireless networks. In this paper, we examine an approach that addresses the receiver heterogeneity problem in cellular multicast with the help of an additional IEEE 802.11 ad hoc network. The basic idea is to allow the cellular receivers experiencing poor channel conditions to use the ad hoc network to connect to those cellular receivers that are experiencing good cellular channel conditions. The good receivers (called proxies) relay multicast data to the poor receivers through the ad hoc network. We specifically consider the third generation cellular high data rate (HDR) broadcast/multicast services (BCMCS). We develop a new routing algorithm to find efficient ad hoc paths from the proxies to the cellular multicast receivers. Unlike existing algorithms (Luo et al. (2003)), our routing algorithm considers the effect of ad hoc path interference. Using simulations of an HDR BCMCS network in conjunction with an IEEE ad hoc network, we show that our algorithm improves the receiver goodput by up to 280% compared to that obtained without using ad hoc paths. We also show that our algorithm achieves up to 98% higher receiver goodput in comparison to the greedy algorithm proposed in Luo.