Research And Design On Precoding In Cooperative Relay System

Now wireless system can provide high transmission rate and good quality ofservice. At the same time, people’s needs are also increased, but the spectrum is limited,so the service of the system can not meet the needs of people.In order to solve theproblem, we find the cooperative relay technology provides a new method of usingspace resource. It means that many communication entities share limited resource toimprove the utilization rate of wireless resource. Therefore, this paper mainly studiesthe pre-coding of cooperative relays.First of all, we studies about the present situation of pre-coding technology andcooperative relays all of the world and make deep research on them.Secondly, we introduce the model of single source and target node with multiplerelays, which can achieve distributed gain. In order to make each transmitted signalsuperpose coherently at the destination, we can use the processing method ofzero-forcing, minimum mean square error, singular value decomposition and QRdecomposition. Then, we combine QR decomposition with zero-forcing based onminimum mean square error, which considers the effect of noise and increases thecapacity of the channel.Finally, we introduce the model of single source with multiple relays and targetnodes, and the joint pre-coding method of block diagonal and singular valuedecomposition, which makes the channel into many parallel sub-channels so thateliminates the interference between users. Then we put up with a method of combiningthe block diagonal with QR decomposition, which can improve the performance of thechannel capacity.