Research On Lattice Network Coding In Wireless Relay System

The wireless relay transmission as promising technology to expand coverage and improve the system’s performance has great significance in research on the wireless communication. Network coding applied in wireless relay system can enhance the transmission efficiency and throughput effectively. Lattice network coding as a network coding scheme based on lattice codes, can realize low possibility of error and achieve higher rate, approaching to the Shannon capacity. This paper focuses on the application of lattice network coding in both two-way MIMO channels and multiple access channels. The main works of this paper are divided into several aspects as follows:In two-way MIMO channels, a network coding scheme based on the lattice codes is proposed, in which the channels are parallelized by using the precoding and related detection technology in MIMO to diminish the inter-stream interferences. In order to improve the system’s performance, power allocation is also applied. The stimulation results of proposed scheme are shown and compared with the performance of traditional scheme, to verify the advantage of proposed scheme.In multiple access channels, compute-and-forward scheme can exploit interference to obtain higher rate. However, the interference cannot be removed since the computed integer combinations of codewords cannot match the channel outputs, which means potential to improve computation rate. In this paper, a compute-and-forward scheme with interference cancellation is designed in multiple access channels constructed by two sources, one relay and one destination, in which the recovered mixed messages can be used by destination to eliminate the impact of effective noise and a higher rate is achieved. The theoretical analysis and stimulation results are also shown to demonstrate that the performance of proposed scheme is superior to the traditional scheme.This paper also introduces a compute-and-forward scheme based on successive interference cancellation in multiple-source multiple-relay channels. The key idea is to use the decoded messages from other relays to eliminate the interference and make the recovered message vectors approach to lattice points. It can be realized when relays can exchange messages with each other. This scheme can improve the bottleneck of computation rate in each relay and enhance the system’s performance.