Cooperative Multicast Strategies under Heterogeneous Link Loss Rates

We consider wireless multicasting over lossy links and explore the benefit of cooperative strategies in which multicast receivers exchange messages. A key feature of the problem considered here is that the source downlink channel has a higher loss rate than the channels between pairs of receivers; this feature implies that completion time may be reduced by offloading transmissions to receiver-receiver links and taking advantage of their higher reliability. Three strategies are analyzed and compared: a strategy in which all transmissions are carried out by the original source node; a strategy in which the original source transmits until it is able to designate a proxy-source among the receiver nodes to complete the multicast; and a strategy in which the original source transmits the minimal number of packets possible and cooperative transmissions among receivers are used to complete the multicast. These strategies are compared in terms of the number of packet transmissions needed to complete the multicast.