Research On Key Technology Of Cooperative Communication Based On Distributed Antenna System

In order to meet the increasing demand for wireless multimedia communication services,the next generation wireless communication systems need to provide higher transmission rate reliable transmission performance.The future wireless communication network is a heterogeneous communication network that supports the integration of multiple wireless networks.Compared with the traditional cell,the introduction of cooperative transmission in DAS can not only obtain the multi-path transmission and multi-antenna performance gain,but also can effectively reduce the transmission power and blocking probability of the mobile terminal.Distributed antenna system is being paid more and more attention because it can significantly improve the transmission performance of wireless networks.In this paper,we mainly research the joint transmit power allocation problem and multi-user transmission strategy in cooperative communication based on distributed antenna system.First of all,this paper introduces two kinds of cooperative communication system model from the point of view of the basic principles of cooperative relaying.The cooperative communication model is essentially the same as the cooperative communication between the fixed relay(MIMO)or the cooperative communication between user terminals.Because in a wireless communication system,each antenna node and user terminal can be used as a potential relay node,here only consider the rational allocation of power to satisfy one or several effective system performance index.Then,this paper considering the problems of energy consumption and performance gives a method of power allocation for single relay and multiple relay.For the single relay system,the optimal solution is given by the Lagrangian multiplier.For the multi-relay system,the Lagrangian multiplier is used to find the set of the optimal solution.Then,the equal power allocation and the optimal power allocation of single relay and multi-relay system are simulated respectively,and the simulation results show that the cooperative transmission improves the system performance.Finally,this article research the cooperative communication based on the distributed antenna system.In the distributed antenna network,the distributed antenna can effectively reduce the blind coverage of the network coverage and improve the transmission rate of users at the cell edge.However,when the cell user communication is active,it is obvious that the distributed antenna can’tmeet the communication needs of most users,and because users have communication needs,multi-user collaboration is difficult to carry out.Therefore,this paper proposes a self-organizing cooperative transmission strategy based on negotiating ability and gives the simulation analysis.For two nearer users,the simulation results show that the team collaboration can make both parties get instant performance gain.