Resource Allocation For D2D Communications In Cellular Networks

D2D communication has the advantages of improving spectral efficiency,decreasing latency,and reducing energy consumption to build more intelligent cellular network with higher capacity,wider coverage,and better service quality.And it has been widely considered as one of the key techniques in 5G.However,when D2 D users and cellular users share spectrum resources,there will be mutual interference between them and the resource optimization model of D2 D communication usually belongs to complicated NP-hard problem.Therefore,it is important and challenging to design reasonable and efficient resource allocation algorithms for D2 D communication.This paper mainly studies the resource allocation algorithms for D2 D communication underlaying cellular network,and proposes two algorithms for different scenarios to improve the system capacity of cellular network.This paper first proposes a resource allocation algorithm for D2 D communication based on joint optimization.Different from existing research,D2 D users can select half-duplex or full-duplex mode in the algorithm.While guaranteeing the communication quality of service of cellular links,the algorithm allows a pair of D2 D users at most to reuse one cellular user's spectrum and maximize system capacity by combining access control,power allocation,mode selection and channel allocation.The algorithm is mainly divided into three steps to achieve.Firstly,according to the quality of service requirements of cellular user and power constraints,find the candidate set of cellular users which are allowed to be reused by the D2 D user.Secondly,find the optimal power solution to the optimization problem of D2 D reusing cellular user's spectrum in half-duplex mode and full-duplex mode based on the convex optimization theory and adaptive particle swarm optimization respectively.Thirdly,convert the problem of mode selection and channel allocation to the maximum weight matching of the weighted bipartite graph and use the classical KM algorithm to solve the maximum weight matching to obtain the optimal mode and a specific cellular user partner for D2 D users.The simulation results show that the proposed algorithm can further improve system capacity and access rate of D2 D users.Considering that in the cellular network scenario where the number of D2 D users is far more than cellular users,the number of D2 D users that can access is limited in one to one multiplexing mode,this paper proposes a resource allocation algorithm based on interference graph for D2 D communication.While guaranteeing the communication quality of service of cellular links and D2 D links,the algorithm allows more than one pair of D2 D users to reuse one cellular user's spectrum and maximize system capacity by selecting cellular user partner for D2 D users.The algorithm first calculates the user's interference limited area and utility function to obtain candidate D2 D user sets reusing the cellular user's spectrum,then selects the largest candidate D2 D set and build its interference graph,and then solves the maximum independent set of interference graph to update the candidate D2 D set,finally removes some D2 D users to guarantee the communication quality of the cellular user and the rest of D2 D users in the candidate set.In this paper,the effects of interference threshold,the number of D2 D users and communication distance of D2 D on the performance of the algorithm are verified by simulation.The simulation results show that the proposed algorithm can further improve the system capacity when D2 D transmitter and D2 D receiver is close to each other.