Research On Physical Network Coding In Wireless Communication

The concept of network coding [1] has been first applied in wireless networks; Theory and research has proved that network coding has its potential for improving network throughput and robustness. Recently, how to apply network coding to wireless networks has received much attention from the research community. The broadcast nature of wireless channel can cause serious interference if several nodes transmit signal simultaneously. On the contrary, physical layer network coding (PNC) was proposed in [2] especially in two-way relay channels to make use of this interference to enhance the network throughput. This paper based on the two-way relay channel (Two Way Relay Channel, TWRC ) considers how to joint design of physical network coding, channel coding and modulation technology in the system model , so that the scheme could guarantee the reliance and improve the rate of channel. The main research contents are listed as follows:First, we introduce the basics concepts of network coding and physical network coding technique, and then analysis complexity, reliability and design methods the existing transmission schemes for the two way relay channel.Second, To decode the superimposed signal efficiently, we proposes a novel scheme of joint physical network coding (PNC) and channel coding based on QAM modulation in two-way relay scenario. The proposed scheme employs a denoising-mapping plan ingeniously, and then maps it to the binary XOR of the corresponding digital bits after rearranging the constellation of QAM modulation. In addition, the scheme takes advantage of the linearity of channel code and MAC-XOR NC code so that digital bits of network coding can be estimated directly. The simulation results show that the proposed scheme outperforms the current PNC strategies significantly in terms of the channel capacity without added the complexity of decoding.Third, we focus on how to joint design of network coding, channel coding and modulation technology. To fulfill this target, we propose a new scheme of joint physical layer network coding and channel decoding for multiple-access channel based on trellis coded modulation (TCM). Since TCM combines channel coding with modulation, the scheme could improve the free distance of the coding sequence greatly, thus more encoding gain will be achieved.