Research On Resource Allocation Scheme For Multi-cell D2D Communications

Along with the rapid development of mobile communication technology,the quality of communication system for users is becoming higher and higher,coupled with the rapid growth of local multimedia data services,so the issue of spectrum resource shortage has become serious.Device-to-Device(D2D)communication technology has been introduced into cellular communication system to solve this problem,which realize the direct communication between short-range terminals by multiplexing the spectrum resources of the CUEs.It can not only alleviate the situation of the shortage of current spectrum resources,but also reduce the burden on the base station,reduce the transmission latency and improve the spectrum utilization rate.While,D2 D communication will inevitably bring additional interference to the cellular system when D2 D users multiplex the spectrum resources of cellular users.So how to design a reasonable D2 D communication resource allocation algorithm,which can suppress the same frequency interference between cellular users and D2 D users effectively,became the key issue of D2 D communication researchers.Therefore,the main work of this paper is as follows:Firstly,the existing Fractional Frequency Reuse(FFR)based resource allocation scheme only selects the preferred candidate spectrum resources for the D2 D users in multi-cell D2 D communication scenario,and multiplexed in the candidate spectrum resources randomly.It didn't minimize the interference between cellular users and D2 D users.So a multi-cell D2 D communication resource allocation algorithm based on FFR technology was proposed in this paper.The algorithm takes full account of the influence of the D2 D users' region and the channel gain on the system throughput.It sets the maximizing system throughput as the goal of the algorithm.There are many optimal cellular users' spectrum resources can be found for each D2 D users to reuse in this algorithm,and then calculate the corresponding reuse ratio.Simulation result shows that the algorithm can not only reduce the inter-cell interference effectively and ensure the communication stability of the cellular users,but also improve the overall performance of the D2 D communication system.Secondly,the interference of D2 D users to cellular users is significant in Soft Frequency Reuse(SFR)based multi-cell D2 D communication system.The interference can weaken cellular user's communication performance seriously.Focus on the problem,a graph-based multi-cell D2 D communication resource allocation algorithm is proposed in this paper.We analyze the system model of the D2 D communication firstly.The algorithm maximizes throughput gain while ensuring the quality of service of cellular users.Cellular users and D2 D users are respectively equivalent to the independent orthogonal subsets in the bipartite graph.The value of the line means the throughput gain that D2 D users multiplex cellular users' spectrum resource.Then the maximum throughput gain problem is transformed into the problem of perfect matching of the bipartite graph,and then output the resource allocation matrix and the corresponding allocation ratio.Simulation result shows that the algorithm can effectively improve the spectrum utilization of the communication system and increase the throughput of the D2 D communication system.