Research On Power Control And Resource Allocation Scheduling Algorithm For Multi - Hop D2D System

With the development of communication technology, future mobile communication system will confront many problems, such as limitation of frequency resource and huge cost of control signaling. D2D (device to device) communication technology, one kind of point to point communication which base on LTE (long term evolution) system can utilize the commercial band of LTE system and other uncommercial band for communication. Message can be passed between two devices without base station. Therefore, D2D communication can be used to solve above two problem of future communication system. By the limitation of transmission power and the incomplete coverage in D2D communication system, equipment with D2D mode can only transmit message to the nearby D2D equipment. Multiple-hop communication is a useful wireless communication technology which can be utilized to enlarge the coverage without increasing equipment transmission power. On the other hand, the co-channel inference among multiple-hop D2D equipment is the bottleneck of D2D system, so we will research power control, interference management and frequency resource allocation of multiple-hop D2D communication system etc.Two-hop D2D communication scenario with co-channel interference will be discussed firstly and others more than two-hop D2D communication scenario can be transfer to two-hop one by slot partition. We design different scheduling algorithm of power control and resource allocation. Under this scenario, we design a central algorithm that central base stations optimize the transmission power of D2D equipment by the information of channel statement between two D2D equipment. We first modeling this problem with quadric cone quadric problem. For the formation of this problem is not convex, so we transform this problem to a convex form approximately and use a convex optimization tool solve this problem. The simulation results verify the correctness of central scheduling algorithm and the improvement of system sum rate.In another condition, transmission power of D2D equipment can’t be scheduling by base station. Under this scenario, game theory can be used to design a distribute algorithm of power allocation. Firstly, we introduce the utilization of potential game, then form the potential function of potential game to verify the existence of Nash equilibrium. According to the potential model, we design a distribute algorithm of power control. On this basis, a threshold is used to decrease the iterative number.The next part of this paper proposed a transmission order (TO) scheduling algorithm of the device to device (D2D) communication system in single cell, which could communicate in low power with limited frequency band. According to the formation of problem, this algorithm transforms the original problem to a boolean second order cone programming (BSOCP) and use bi-level method to optimize BSOCP. Meanwhile, the links are scheduled according to ITLinQ algorithm and TO scheduling. The simulation results verify the correctness of joint scheduling algorithm and the improvement of system sum rate.On the basement of foregoing partition, we research another scenario that D2D equipment are not asynchronous and would get mutual interference. We use a proposal algorithm to approximate the optimistic solution with relaxation factor method, firstly get the closed expression of optimistic power, then we modify the transmission power to decrease the co-channel interference. At last, the simulation results verify the correctness of proposed power control algorithm and the improvement of system sum rate.At the end of this paper, we summarize the power control algorithm for the scenario of multiple-hop D2D communication. We analysis the advantage and shortcoming of our algorithm in this paper and propose the future research directions.