Performance Research Of D2D In Cellular Networks

With the development of mobile networks and devices, people show more dependence on mobile devices to accomplish file-sharing、downloading、communication and some other applications, which proposes higher requirements on the performance and bandwidth of mobile network. However, the non-renewability and inefficient utilization of spectrum has always been the bottleneck on the path of wireless system development. In addition, the booming of local services will bring great challenges to current networks, which requires future wireless systems to develop new technologies to support local communications. Nowadays, the International Mobile Telecommunication Advanced (IMT-A) is sparing no efforts on collecting various appropriate solving method to the contradictory between great demands and plane bearing ability of current networks.Device-to-Device (D2D) technology underlying cellular networks is considered to be a promising technology of improving the utilization of system spectrum, and it is also regarded as a great match to local services in future networks. D2D technology in computer networks has seen splendid success, such as the file sharing system. When bring it into wireless cellular networks, nearby users can form a D2D user pair and transmit signals to each other directly on a lower level of power. The local transmit power only introduces local interference to the system and improves the utilization of spectrum greatly. From other point of view, D2D technology takes advantages of small communication distances of local service users. In other words, there is no need for the base station to forward signals for local service users. In a D2D enabled cellular network, how to coordinate the cellular users and D2D users is a huge challenge.In this paper, we put our emphasis on the establishment of D2D links, the evaluation of performance influence factors of D2D users, as well as the performance optimization schemes. Particularly, the optimization schemes include the power control, the resource allocation and the mode selection for D2D users. Simulation results show that our optimization schemes coordinate the mutual interference between cellular users and D2D users, as well as that among different D2D users. To diminish the complexity of system computation, a mode mapping method for D2D users has been proposed, with which the base station can determine users’ modes and resources based on the position information. Numerical results demonstrate that this mode mapping scheme can reduce the computation complexity largely without damaging the performance. The remainder of this paper is organized as follows. Chapter I gives a brief introduction of the mobile network and D2D technology. A modeling method of D2D users underlying cellular networks is presented in chapter Ⅱ. In chapter Ⅲ, the proposed optimization schemes are demonstrated, including the establishment of D2D links and the optimization schemes. In chapter Ⅳ, an introduction of system model and platform is provided. The simulation results and analysis are provided in chapter Ⅴ. Finally, Chapter Ⅵ gives some concluding remarks.