Distributed cooperative diversity method for P2P file sharing over wireless ad hoc network

In wireless ad hoc networks, if we design the cooperative diversity method during download process to utilize the wireless medium and common files source, the file download performance would be improved significantly. In this paper, we propose novel protocols, opportunistic downloading protocol (ODP) and opportunistic DF broadcast downloading protocol(ODFBP). Our new protocols could adaptively work in different file distribution scenarios. ODP corresponds to single requesting peer, it first select the source with the best channel condition from M available local neighbor source file peers and then requests the file data from the selected source. We introduce a distributed CDF based mu-law time expire source choice method where each source peers only have the knowledge of local instantaneous channel gain. While ODFBP work in dual requesting peers scenario, it includes our distributed common source choice algorithm and DF (decode and forward) protocols for cooperative broadcast channels. And the information theoretic analysis of outage probability shows that the ODFBP schemes can obtain M(the number of the file source) times diversity-multiplex tradeoff gain.