Cross Layer Analysis and Optimization of Relay Networks

Recently, there has been significant interest in relay networks. Due to the wireless signal power attenuation with transmission distance, using relays in a wireless network can make wireless networking more bandwidth and energy efficient at the expense of requiring multiple transmission for a single packet. Relay networks require a medium access (MAC) protocol because it involves multiple-hop transmission for communication between the source and destination. However, relay network research has considered only the physical layer ignoring overhead from MAC operations. In this thesis, we analyze and optimize the energy and bandwidth performance of relay networks considering both the physical layer and the MAC layer. Using cross layer analysis, the energy-throughput tradeoff of relay networks is determined. It is shown that relaying can improve performance significantly even when including the overhead from MAC operations. We also optimize the transmit power level and number of hops for relay networks. Lastly, a simple relay enabled MAC protocol, SRMAC, which enables cooperative relay transmissions is proposed and analyzed. It is shown that the SRMAC protocol improves the performance significantly