Network Coding In Wireless Cooperative Communication

Network coding theory is proposed based on the wired-network and possesses the properties of enhancing the network throughput, increased network security and multiple media access, etc. The broadcast property of wireless communication network provides an environment for network coding. Therefore, the physical layer network coding in the wireless network has been a hot topic. Network coding theory changes the traditional processing method in the network that the routers are only responsible for the storing and forwarding the information. It proposes that the relay can encode the received information before forwarding it. Such a processing can improve the throughout of the network, and even make it reach the limit of the network capacity. The result of research shows, the network coding can not only improve the throughout of the network, but also can balance the network load, enhance network robustness, and even improve the security of the network et al. This paper mainly focuses on the application of network coding in the bidirectional wireless relay network. The relay nodes commonly use two relay protocol: amplify and forward (AF),decode and forward (DF) . The amplify transmitted protocol amplify the noise, and the decoding transmitted protocol is an interference limited protocol.In order to avoid the lack of methods which are introduced above, a simply network coding method based on module-q group and made use of same modulation in both sides is proposed. The proposed method is not need the relay node to transmit the modulation scheme which is used by the relay node to both source nodes. During the process of designing the denoising-forward function which rely on the phase and the amplitude of the channel coefficient, so we take use of the two features to improve the denoising-forward function, one is based on the phase synchronism and the amplitude compensation. .