Research On Radio Resource Management Of Device-To-Device Communication Underlay Cellular Networks

The development of wireless communication makes more and more kinks of mobile terminals accessing into the wireless networks, which causes a big change to the structure of traditional cellular networks, the huge number of mobile users brings new challenges to the radio resource management in the wireless system, and at the same time, the shortage of spectrum resources becomes more and more serious. As a kind of promising technology, Device-to-Device (D2D) technology can provide a direct link between the users to communicate in order to enhance the spectrum efficiency, enlarge the coverage of the basestation, promote the system capacity, reduce the user power consumption, improve the instant throughput and so on. D2D communication has become a key technolgoy for the future 5G communication system, which draws much attention in academic world these years. And some standard organizations such as 3 GPP has already included this technology into the future standard work, so D2D technolgy has a wild application prospect.It needs an effective way to combine D2D communication with the traditional cellular system. This dissertation focuses on the radio resource management of D2D underlay cellular networks, and researches the cellular and D2D hybrid networks. In order to solve the interference problem, spectrum resource allocation and so on, which these problems are existed in this hybrid system. And the main research contents of this dissertation are as follows:First, this dissertation research the D2D transmission capacity with cellular user coopertation in the cellular and D2D hybrid networks. The dissertation proposed a scheme that cellular user can allocate a part of power to cooperate D2D to communicate, and this scheme can not only enhance the transmission capacity in D2D system, but also ensure the cellular communication. In this part of research, homogeneous Poisson point process is used to model the cellular and D2D hybrid networks during the analyzing D2D communication network with cellular cooperation. Then the existance probability of assisting cellular users which cooperate the D2D communciations is derived out and the transmission distance expectation is also obtained. Then the successful transmission capacity, D2D tranmssion capacity and the constraints of the system is evaluated. From the analysis of convex optimization, the optimal D2D transmission capacity is got under the cellular user cooperation. The simulatin at last analyzes the influence of interference to the cellular and D2D hybrid networks.Second, this dissertation analyzes the spectrum reuse of D2D communication underlay cellular networks. Under the premise of D2D reusing the cellular uplink resource, a D2D spectrum reuse scheme based on region division is proposed. A series of annular region is divided out in the cell which the base station is the center. Each region allows different number of D2D users to reuse the spectrum, and the cellular communication can be ensured when D2D reusing the spectrum resource. In the analysis, stochastic geometry is adopted to model the system, the cellular outage probability transfers to the points appearance probability of the homogeneous Poisson point process on two dimensional plane. With the help of Lambert W function, the range of each region in the cell is obtained. Fom the simulation at last, the relationship between the region division and the parameters such as transmission power, tranmission distance and so on is discussed, the results also verifies the spectrum reuse scheme can allow mulitple D2D users which far from the base station to reuse cellular uplink spectrum resources at the same time.Third, this dissertation analyzes the user resource allocation and power control in cellular and D2D hybrid networks. Based on stochastic geometry, the cellular and D2D hybrid networks are analyzed from two aspects:1) According to the occupation of different frequency resources, the user mode proportion is divided on multiple bands, then with the help of convex optimization, the user mode proportion on different bands are obtained, finally a realization algortihm is proposed to get the D2D user resource allocation and mode proportion, then the optimal capacity is got; 2) In the cellular and D2D hybrid networks, the D2D user allocation problem is firstly optimized on multiple bands, secondly, D2D transmission power is then optimized on multiple band, finally a D2D user allocation and power control algorithm is proposed, and the optimal D2D user density and transmission power on each band are obtained. The simulation analysis demonstrates the constraints from the total user number and terminal tranmission power in the hybrid networks, also the results discussed the influence of interference to the D2D user allocation and power control in the system.