Research On Power Allocation Problem For Two-way Relay System Based On PNC

Relay technology and network coding, being emerging communication technologies,have greatly contributed to the improvement of wireless communication systems that itspower and frequency-band limited, no matter in the aspect of capacity or efficiency. Theformer technology can enlarge the information transmission radius by the relay, while it cannot achieve the maximum flow transmission; The later one, different from the traditionalstore-and-forward mode, takes certain coding method to process the received massage insome relay nodes, in order to improve the performance, such as throughput, robustness andmaintainability, of the communication system. Since both communication technology cancomplement each other, applying network coding technology especially physical-layernetwork coding to relay cooperative network has become a hot research topic.The research of this thesis includes the following points:First, the transmission characteristics of wireless channel and the application of relaytechnology in wireless network are introduced. Then, the fundament theory, latest progress,advantages and disadvantages of network coding are explained. Finally, the application ofnetwork coding in relay technology is studied.To improve the BER performance of two-way relay network based on physical-layernetwork coding in the rayleigh fading environment, one optimized power allocation scheme isproposed in this paper. The power optimized scheme introduces the turbo code into thecommunication system so that the relay point can transmit the encoded signals at a relativelylow power and ensure the source nodes receiving encoded signals at a low bit error rates. Therest of the power in the relay point can be allocated to the two source nodes to further improvethe BER performance of the two source nodes in the second time slot. And then an optimizedpower allocation scheme to improve the outage probability of the system is proposed in thispaper. Numerical results show that the two optimal power allocation schemes proposed in thispaper can improve the BER performance and outage probability performance of the system,respectively.In order to improve the network sum-rate of two-way relay network based on PNC, oneoptimal power allocation scheme is studied in this paper. Numerical results show that it cangreatly improve the network sum-rate when the variance of the Ganssian noise in the twosource nodes is greater than the variance of the Ganssian noise in the relay node.