Research On Resource Allocation Algorithm Of D2D Communication In LTE System

With the rapid development of wireless mobile communications business,the demand for wireless spectrum services increases sharply,and the limited spectrum resources could not meet the people's growing needs of spectrum any more,thus it is urgent to improve the spectrum utilization nowdays.The Device-to-Device(D2D)technology not only can effectively improves the system throughput and spectrum utilization,but also can expand the cell coverage,Therefore,this thesis will further study the resource allocation algorithm in D2 D communication that can better improve the system spectrum utilization.The main parts of the thesis are as follows:1.The traditional resource allocation algorithm ignores the fairness problem between the cellular users and the D2 D users in D2 D communication,which leads to the unfair resource sharing among different users.Aiming at this problem,this thesis proposes an improved fairness-based D2 D resource allocation algorithm combining the idea of regional restriction.Based on the multi-cell application scenario,the cellular users that meet the conditions are selected as the candidate cellular users according to the interference value between the D2 D and the cellular users.Then,according to the threshold conditions of the base station and the cellular users,the algorithm calculates the communication area that satisfying the threshold conditions.Finally taking the variation of the weights value before and after joining the D2 D user into account,that is,the priority of resource is set based on the principle of minimizing the damage of fairness.The simulation results show that the proposed algorithm can effectively improve the spectrum utilization and system fairness.2.Aiming at the problem that some users cannot allocate resource in the current clustering algorithm,an improved relay forwarding scheme based on D2 D clustering is proposed.To begin with,the D2 D users are clustered according to the size of the interference between the D2 D and the cellular users.But the clustering would cause that some D2 D users cannot reuse the resources successfully.Integrating the concept of relay communication,a relay forwarding scheme is proposed which is based on a two-stage priority.The proposed algorithm chooses the D2 D users that have successfully assigned the resource as a relay,and processes the hierarchical forwarding according to the corresponding priority of the quality matrix,making that more users could reuse the resources and improve the system performance.The simulation results show that the reuse rate of D2 D users and system spectrum utilization of the proposed algorithm are obviously better than the the traditional algorithms.