Research Of Relay Selection Based On Network Coding

Cooperative communication uses the broadcast nature of the wireless channel to improve the reliability of the wireless channel. In cooperative communication the same type of information can reach the receiver independently through different wireless channel. Meanwhile, network coding can improve the utilization of system resources and network throughput. Resent researches show that the combination of cooperative communication and network coding, can improve network throughput, reduce transfer times, use network bandwidth more efficiently. The key issue is to choose suitable relay nodes and different transmission modes, in order to optimize network performance.This paper focuses on design and implementation relay selection strategies by combines cooperative communication with network coding to get better performance in wireless network, i.e,802.16m network and mobile ad hoc network, and designed different strategies for them. We make the following two contributions:First, in802.16m network, as its resources are limited, a novel relay selection algorithm named Relay Selection algorithm combined Throughput and Resource Allocation(RSTRA), is proposed for different network load. When only few mobile nodes request to transmit, which means that the amount of network resource is enough, RSTRA selects the correct relay and transmission scheme to maximize the network throughput. When a lot of mobile nodes want to transmit, RSTRA optimizes the total amount of resource allocation while satisfying all requests. Simulation results show that RSTRA achieves higher throughput than CNCRA when the network load is light. When the network load is heavy, RSTRA achieves the same throughput as CNCRA, but needs less resources.Second, in Mobile Ad hoc networks, due to the limited energy, the energy consumption is an important problem in the network. This paper proposed a Mobile ad-hoc networks Energy efficient MAC layer protocol(ME_MAC) combining network coding with cooperative communication. The protocol use the energy consumption as it’s indicator. In the single-hop range, each candidate relay node first calculates energy consumption of direct transmission, cooperative transmission and cooperative network coding transmission, and choose the smallest transmission scheme. Secondly the candidate relay node calculate it’s backoff time based on the energy consumption, and has the smallest backoff time node as the relay node. Simulation results show that, ME_MAC protocol compared with only using cooperative communication DEL_MAC protocol, has less average energy consumption of a single packet transmission.