Opportunistic Scheduling and Performance Analysis on Wireless Network Coding

Network coding has been shown to be able to improve the throughput and power efficiency of wireless networks by mixing packets from different flows into a single packet. However, forcing packets to be coded may induce large delay and packet loss rate which is intolerable to some services such as real-time communications. Considering the diversity of traffic flows and the stochastic nature of the packet arrival process in wireless networks, we propose an opportunistic scheduling called Probabilistic Network Coding with Priority (PNCP) method. The relay node can transmit either network-coded or un-coded packets. Service priority and queue state are the two most important facts that determine a packet´s transmission with or without network coding. By using a Markov Chain model, the average packet delay and packet loss rate of PNCP are presented. We validate the theoretical results through simulations and demonstrate that it can serve different flows with priority. More importantly, we discuss the impact of different parameters on the performance of PNCP and show that the opportunistic scheduling can significantly reduce the packet loss rate and average delay.