Resource Allocation Algorithm Research In Device-to-Device And Cellular Hybrid Network

Device-to-Device(D2D)communications which allows proximity user transmiting data directly to each other without going through the base station could reduce the communication delay between devices,increase instantaneous data rate,reduce the load of cellular networks.The hybrid network consists of D2 D communications and cellular communications can improve spectral efficiency?energy efficiency and enrich the application scenes.But,D2 D communications reusing cellular spectrum brings new challenge to interference coordination.In order to reduce the interference between D2 D user and cellular user and improve spectral efficiency,it is necessary to reaserch resource allocation technology.The thesis focuses on how to improve the spectral efficiency and reduce the interference by resource allocation when D2 D communication reusing cellular spectrum in the whole load network.It mainly includes the following aspects:Based on the basic research object of resource allocation in D2 D and cellular communication networks,the interference between D2 D user and cellular user was analysed,and the existing resource allocation algorithm was reaserched about improving frequency efficiency and reducing interference in hybrid network.In view of the D2 D users reusing cellular spectrum leads to the performance deterioration problem of cellular users,so a new resource allocation scheme was proposed.The scheme which maximizes the sum of throughput gain can reduce the rate loss of cellular users and improve the rate of D2 D users simultaneously,including two steps.It first calculates reuse gain for single D2 D pair and single cellular user.D2 D user can access only the reuse gain greater than zero.Next,a maximum weight bipartite matching is developed to select reuse pair to maximize the overall network throughput gain.Numerical results show that the proposed scheme can significantly improve the performance of the hybrid system in terms of the overall network throughput gain and the average rate loss of cellular user.In view of the classical fractional frequency reuse mode exists inter-cell interference for cell users and D2 D users,a heuristic resource allocation algorithm based on a new fractional frequency reuse mode was proposed.The heuristic algorithm consists of three steps: First,determining the initial set of D2 D users of the multiplexed cell user,which means the D2 D user within the set has interference to the cell user within the threshold.Second,the D2 D user candidate set of the multiplexed cell user is determined,which means the D2 D user in the set satisfies the QoS requirement.Finally,the D2 D user access set of the multiplexed cell user is determined,which means the performance of the D2 D user multiplexing cell user in this set is optimal.The simulation results show that the algorithm can reduce the inter-cell interference and improve the QoS satisfaction of the cell users and D2 D users.The research of the thesis can provide a reference for the resource allocation scheme of cellular and D2 D communication network.