Opportunistic Cooperative Network-Coding Based on Space-Time Coding for Bi-Directional Traffic Flows

In multi-hop wireless networks, network coding can take advantage of the bi-directional traffic flows to increase the achievable throughput. To combat fading in wireless channel, cooperative diversity is integrated into the network-coding schemes. In this paper, we propose an opportunistic cooperative network-coding scheme based on space-time coding (OCNC), which combats channel fading and improves resource efficiency and network throughput. Focusing on the bi-directional traffic flows in wireless cooperative relaying networks, we develop and analyze the outage probabilities and the network-coding gain of different bi-directional relaying schemes. The numerical results show that in contrast to traditional scheme both full diversity (i.e. K-order diversity in case of K relay nodes) and asymptotical 4/3 times of network-coding gain are achieved by OCNC. In addition, because of opportunistic relaying of multiple nodes, the network-coding gain is more considerable in the low and middle SNR regimes.