Research Of Optimal Power Allocation For Network Coding Cooperative System

In wireless communication, in order to combat the fading of the wireless channel cooperative diversity has been put forward. It forms virtual multiple input multiple output (MIMO) through multiple mobile terminal with single antenna sharing each other's antenna to improve the system performance. Network coding theory is a new technology which breaks the information processing methods of nodes in traditional communication networks. The relay does not focus on simple store-and-forward, but encode the information that passes by, therefore, the throughput and reliability of entire network are enlarged. With the deep study of cooperative systems, power allocation technology is introduced to the cooperative system. Power allocation technology play an important role in reducing the symbol error rate of cooperative system and improving cooperative system capacity.Firstly, this paper introduces the basic principle of cooperative diversity and analyzes some common cooperation system. Then cooperative diversity based on network coding is discussed.Secondly, the optimal power allocation schemes to optimize BER and channel capacity are analyzed in Amplify and Forward (AF) cooperation diversity system and Decoded and Forward (DF) respectively under the conditions that the total power is constant. The performance of AF and DF cooperation systems adopting the optimal power allocation schemes are simulated and compared in different channel conditions.Finally, channel capacity and outage probability of network coding cooperation system and common cooperation system are studied respectively. An optimal power allocation scheme was proposed and the theoretical analysis and the simulation results were obtained. The simulation results show that outage probability of the network coding cooperative diversity is lower than that of the common ones when sending node is close to the relay, On the contrary, the outage probability of network coding cooperation system is higher than that of the common ones when sending node is far from the relay, but the difference is slight.