Research On Resource Allocation Algorithm For D2D Communication Underlaying LTE-A System

With the development of mobile communication and the growth of multimedia services, the lack of transmission rate and spectrum resources have already become a big challenge. In order to alleviate the problems, Device-to-Device Communication was introduced to the LTE-A system. It can not only increase the throughput and spectrum efficiency, but also greatly improve the service of cell-edge users, especially combining with MBMS. However it also can bring a lot of interferences. In order to reduce the interference, more attention should be paid to D2 D resource allocation algorithms.Through the research, it is found that most D2 D resource allocation algorithms pay no attention to the fairness of the system. To this end, a resource allocation algorithm is proposed to improve the fairness of the system. Firstly, in order to reduce the complexity of resource allocation algorithm and interference both, this thesis put forward the D2 D communication restricted area and cellular user resources are limited reuse area. Secondly, a D2 D resource allocation algorithm is proposed to improve the fairness and throughput of the cellular system. Finally, the multiplier method for nonlinear programming problem is used to find the optimal transmit power of D2 D users and it is multiplexed cellular user. The simulation results show that the proposed algorithm can not only improve the throughput of the system, but also significantly improve the system fairness, while comparing with the existing scheme.In order to make a greater use of the spectrum resources of the system, a D2 D multicast resource allocation algorithm is proposed. Due to the shortage of D2 D multicast clustering algorithm, a low complexity clustering algorithm is proposed to improve the performance of the system. In view of the disadvantages of the existing D2 D multicast resource allocation algorithm, a new D2 D multicast resource allocation algorithm is proposed. Firstly, a graph coloring algorithm is proposed to divide D2 D multicast users into several sets. D2 D multicast users from same set reuse the same cellular user resources. Secondly, the KM algorithm is used to select an appropriate cellular user for the D2 D multicast cluster set. The simulation results show that the proposed D2 D multicast clustering algorithm can effectively improve the ratio of the served NACK users and the throughput. Furthermore, the proposed D2 D multicast resource allocation algorithm can significantly increase the spectral efficiency and the ratio of the served D2 D multicast users.