Deterministic structured network coding for WWAN video broadcast with cooperative peer-to-peer repair

Recent research has exploited the multi-homing property (one terminal with multiple network interfaces) of modern devices to improve communication performance in wireless networks. Cooperative Peer-to-peer Repair (CPR) is one example where given simultaneous connections to both a Wireless Wide Area Network (WWAN) and an ad-hoc Wireless Local Area Network (WLAN), peers receiving different subsets of WWAN broadcast packets can exchange received WWAN packets with their ad-hoc WLAN peers for local recovery. In our previous work, we have shown that by using Network Coding (NC) to linearly combine received packets into new CPR packets for local exchanges, packet recovery can be improved. Moreover, by imposing Structure on Network Coding (SNC) when encoding a CPR packet, decoding of at least the important packets becomes possible in the event when insufficient number of CPR packets were received for full recovery. Given SNC is used during CPR, the key decision for each peer is to determine which SNC type to encode a repair packet at each WLAN transmission opportunity. The decision is further complicated by the observation that peers in general receive different numbers of CPR packets from neighbors due to varying amount of WLAN link contentions and interference experienced. In this paper, we propose a novel counter-based deterministic SNC type selection scheme. Using this approach, we show that a simple local optimization procedure, taking advantage of available neighbors´ state information, can be easily implemented to further improved CPR performance. Simulation results show that our proposed scheme outperformed our previous randomized SNC type selection scheme by up to 1.87dB.