Outage Performance Analysis And Interference Suppression Technique Investigation For Cooperative Relay-based D2D Communication In The Cellular Network

With 5G coming,the demands for the data transmission rate and the network quality of service(Qo S)are enhanced gradually,and the current wireless communication technologies and network infrastructures have been difficult to meet the requirements for wireless services.As one of the key technologies in the 5G cellular system,Device-to-Device(D2D)communication has attracted considerable attention in recent years.D2 D enables two mobile user terminals to communicate directly without traversing the base station(BS)and reuses the spectrum resources,which not only offloads the cellular traffic but also decreases the communication delay,saves the terminal energy,increases the spectrum utilization and cell throughput.Cooperative relay technology is used as an important means to construct the 5G heterogeneous network(Het Net),and it has been widely adopted in the 4G cellular system.Cooperative relay utilizes the terminal cooperative spatial diversity to cope with the multi-path fading,which not only improves the link reliability but also improves the spectral efficiency,extends the network coverage and increases the data rates.In this dissertation,the cooperative relay-based D2 D communication which combines the D2 D system with the cooperative relay technology is proposed to enhance D2 D communication quality and expands D2 D communication covering area,and then improves the overall cellular system performance and network Qo S.For the proposed cooperative relay-based D2 D system,the investigation is being carried out form two major aspects of the outage performance analysis and the interference suppression scheme design.Details are summarized as follows.Firstly,the outage performance of cooperative relay-based D2 D communication in the spectrum orthogonal mode is investigated.The explicit outage probability expressions for cooperative relay-based D2 D with Decode-and-Forward(DF)and Amplify-and-Forward(AF)protocols are both provided,and the effects of network parameters including terminal transmit power and terminal locations on outage probabilities are explored.Accordingly,the relay selection method is further proposed by comparing the outage probabilities of cooperative relay-based D2 D with that of traditional direct D2 D.Secondly,the outage performance of cooperative relay-based D2 D communication in the spectrum reuse mode is investigated.With consideration of the scenario where the allocated uplink resources are shared by cooperative D2 D communication,the exact expressions for the average received cellular interference power of the D2 D receiver and relay are derived,and the interference power variation tendency according to the locations of cooperative D2 D terminals is characterize.Based on this,the explicit outage probability expressions for cooperative relay-based D2 D with DF and AF protocols are provided,along with the exploration of network parameters effection on outage probabilities,and then the relay selection method is proposed by comparing the outage probabilities of various D2 D transmission modes.Next,the interference suppression problem in the interference scenario where one D2 D pair reuses the cellular resource is investigated.Based on the virtual MIMO D2 D system with the introduction of the cooperative relay,the interference suppression problem for D2 D is first formulated as an optimization problem to maximize the Signal-to-Interference-plus-Noise-Ratio(SINR)of the D2 D receiver,where the precoding vector of the D2 D transmitter and the decoding vector of the D2 D receiver are regarded as the optimized variables,and then a suboptimal algorithm and an optimal one are proposed to solve this optimization problem.In the two proposed algorithms,the suboptimal one divides the original optimization problem into two sub-problems which include minimizing the cellular interference power and maximizing the desired signal power,and solves the two sub-problems in order by Rayleigh-Ritz theorem to obtain the corresponding precoding vector and decoding vector.The optimal one directly works out the original optimization problem by the generalized Rayleigh quotient form of the D2 D received SINR,and derives the optimized vectors.Finally,the interference suppression problem in the interference scenario where multiple D2 D pairs share the same cellular resource is investigated.Also based on the virtual MIMO system with the introduction of the cooperative relay,the optimization processing of all D2 D transceivers is first transformed to one of solving nonlinear equations by the generalized Rayleigh quotient form of the received SINR of any D2 D pair in the network,and then a D2 D received SINR improvement algorithm is proposed to deal with the nonlinear equations.The proposed algorithm not only achieves the goal of suppressing the network interference but also ensures the fairness of D2 D communication performance.