Research On Cooperative Relay Technology Based On Physical-layer Network Coding

The network coding is widely concerned by the academic community because of its ability to reach the maximum capacity of the maximum flow-minimum cut.Cooperative communication is a technology that can use the virtual antenna technology to obtain diversity gain,which has been proved to improve the performance of communication system.Physical-layer network coding as a branch of the network coding,which itself contains the idea of cooperative.By usingthe intermediate nodes to deal with information,Physical-layer network coding can improve the system throughput,reduce the system's probability of interruption.In the wireless cooperative communication system,the introduction of network coding technology can further enhance the network throughput,security and robustness.This paper explores the influence of the relay system on the system capacity when using the physical layer network coding.On this basis,a power allocation strategy is studied with the aim of maximizing the system capacity.In addition,to ensure the accuracy of data transmission,the probability of the two-way relay system based on physical layer network coding is analyzed.The main work is as follows:1.This paper established the mathematical model of the two-way relay system based on physical-layer network coding,analysed the signal-to-noise ratio of the Source node and derived the arithmetic fault access of the channel capacity.Through the simulation experimentthe thesis compared the channel capacity of the two-way relay system based on physical-layer network coding with the two-way relay system based on direct network encoding and the traditional two-way relay system.Simulation results show that the channel capacity of physical-layer network coding is the highest,and that the system can achieve the maximum channel capacity when the node R is in the middle of the node A and B.2.With the total transmit power constraints,power allocation problem which aims at maximize the system channel capacity is studied.To be more specified,an optimal power allocation strategy is elicited.The experimental results show that the channel capacity of PNC based two-way relay system with optimal power allocation is always higher than that of PNC based two-way relay system with average power allocation.3.Theoutage performance of two-way relay system based on physical layer network coding is studied.Firstly,the outage probability of two source nodes was analysed when the information transmission of two-way relay system is considered as two different information flows.Afterwards,the outage probability of the whole system is analysed as a whole,and the lower bound of the outage probability is obtained.The simulation results show that the outage probability of the two-way relay system is directly related to the signal-to-noise ratio of the system,the location of the relay node and the target rate of the system.With the signal-to-noise ratio increases gradually,the outage probability of node A and node B decreased gradually.When the relay node R is located in the middle of node A and B,the outage probability of node A and B is equal to each other and achieve the minimum outage performance.Meanwhile,the node closer to relay node has better outage performance.