Resource Management And Transmission Optimization Design Of D2D Communications In Heterogeneous Cellular Networks

The large increase of mobile devices in the future wireless communication network will lead to an exponential increase in mobile traffic.In order to support a large number of user access and mobile devices,Device-to-Device(D2D)communication technology and Non-Orthogonal Multiple Access(NOMA)technology are considered to be promising technologies in the new generation of mobile communication.This dissertation mainly studies two scenarios of D2 D communication underlaying cellular networks,models the resource management problem into a mathematical problem,and proposes the optimal resource allocation scheme,and further analyze the advantages of the proposed algorithm through the simulation results.Its main work consists of the following two aspects:(1)This dissertation investigates the resource allocation problem of D2 D communication from physical layer security scenario,we consider the “one-to-one” D2 D communication mode,and propose the optimization problem of maximizing the sum data rate of D2 D pairs while guaranteeing the constraints of cellular users(CUs)data rate and secrecy rate requirements.Due to the spectral reuse between CUEs and D2 D pairs,D2 D receivers have the opportunity to decode the data transmitted by CUEs under the physical layer security,and D2 D receiver will be regarded as the eavesdropper.Thus,we formulate a problem of maximizing the sum data rate of D2 D pairs while guaranteeing the constraints of CUs' data rate Qo S and security requirements.Due to the existence of continuous variables and binary variables,which belongs to the mixed integer nonlinear programming problems.In order to solve the problem effectively,we decompose the resource allocation problem into power allocation and subcarrier assignment.First,we assume that the subcarrier assignment of D2 D pairs has been given,and obtain the closedform optimal power allocation expression of CUs and D2 D pairs.Based on the derived optimal power solution of CUs and D2 D pairs,the problem is transformed into the problem of maximizing the sum of D2 D SINR,we use the Hungarian algorithm to select the optimal subcarrier for D2 D pairs.The simulation results show that the proposed joint power control and subcarrier allocation algorithm can improve the sum data rate of D2 D pairs.(2)This dissertation studies the D2 D communication resource management problem with the combination of uplink and downlink subcarriers and the application of NOMA technology.We consider the “one-to-many” D2 D communication mode,and propose the problem of maximizing the sum data rate of NOMA-based D2 D groups while guaranteeing the minimum data rate requirements of both CUs and D2 D groups.Since the problem involves continuous power variables and binary subcarrier assignment variables,it's difficult to solve problem directly,so we decompose the problem into subcarrier assignment sub-problem and power control sub-problem.We first use the Hungarian algorithm to select the optimal one-to-one subcarrier allocation based on the sum channel gains of NOMA-based D2 D group,if there exists N-D2 D groups with unallocated subcarriers,we match the remaining NOMA-based D2 D groups according to the D2 D group selection rule.On the basis of obtaining the subcarrier assignment scheme,we calculate the optimal transmit power of CUs according to the constraints of CUs' uplink and downlink data rate,then convert the non-convex problem of D2 D group power into a convex problem,and obtain the optimal transmit power of each receiver in the group.Finally,simulation results demonstrate that the proposed joint uplink and downlink resource allocation algorithm can greatly improve the sum data rate of D2 D groups.