Cooperation-based Opportunistic Network Coding in Wireless Butterfly Networks

Opportunistic Network Coding (ONC) has attracted much attention recently. The main improvement of ONC over the traditional network coding is that ONC allows the encoding node to decide whether it employs network coding based on the status of all its input streams. However, due to the nature of fading, wireless links may not always be reliable. Thus, the performance gain of ONC over traditional methods may be diminished due to wireless links in deep fading. Fortunately, some techniques, such as ARQ (Automatic Repeat reQuest) and cooperative diversity etc. can be used to mitigate it. In this paper, we consider the wireless butterfly network topology, a basic component of complex wireless networks. In order to improve the network performance via taking the advantage of ONC, ARQ and cooperative diversity, we propose a new Cooperation-based Opportunistic Network Coding (CP-ONC) protocol and then analyze its performance in terms of network throughput and delay. The advantage of CP-ONC over ONC is that it employs truncated ARQ and cooperative diversity to enhance the reliability of the wireless links. Various simulations show that CP-ONC achieves better gain over ONC in terms of network throughput and delay, especially in low Signal to noise ratio (SNR) region.