Hybrid Network Coding and Cooperative Relaying Schemes for Bi-Directional Communication Systems

With the purpose of improving the performance of next generation wireless networks, cooperative relaying (CoR) and network coding (NC) are promising techniques for bi-directional or two-way transmissions. Compared to CoR, NC can reduce the number of bi-directional transmission slots, which results in higher total throughput. However, the asymmetric traffic condition has significant impact on the bi-directional throughput of NC. CoR is robust against asymmetric traffic conditions when adaptive transmission direction switching (TDS) based on channel and traffic condition is applied. In order to improve the throughput of NC even under asymmetric traffic condition, two hybrid NC and CoR schemes with opportunistic scheduling are proposed in the present paper. In the proposed schemes, adaptive resource allocation is realized for each transmission protocol, and the impact of the traffic ratio and the relay position on the throughput is investigated. Simulation results reveal that the proposed schemes not only achieve higher throughput than the conventional scheme but are also robust against asymmetric traffic conditions. Moreover, the results can contribute to the development of relay selection and routing schemes for practical networks.