Application Of Physical Network Coding In Cooperative Communication System

Cooperative communication and network coding, being emerging communication techniques, have greatly contributed to the improvement of communication systems, no matter in the aspect of capacity or efficiency. The former one is based on the relay communication system. The difference between them is that the relay node is replaced by the user node in cooperative communication system. The cooperative communication system gets diversity gain and it also can be seen as a virtue MIMO system in the reality; while the later one, different from the traditional signal processing mode in some routing node, which only store-and-forward the received massage, takes certain signal processing method in some routing nodes in order to improve the performance, such as throughput, of the communication system.Because the similarity of these two system, we focus on the combination of these two new fields. Especially, we propose a new cooperative communication system which base on the physical network coding. In this paper, the new system was tested in three classical models. After the analysis, we have got some key parameters of these classical models such as the outage probability and the diversity gain. It is proved that the new cooperative system have better performance in some certain circumstance. Nevertheless, the system mentioned above has its own defect. So we use the mix-signal processing mode, denoise-and-forward (DNF), in cooperative nodes. Because of selecting the best mapping region, the DNF can reduce some noise of the mix-signal, and it can also increase the signal noise ratio (SNR) towards reducing the number of sending symbols. Finally, the simulation by Matlab proved that the cooperative systems which adopting DNF have better performance to the other systems without DNF.