A Study On Resource Allocation Schemes For D2D Communication In Cellular Networks

With the rapid development of wireless communication, the increasing data rate demand in local area service and gradually increased spectrum congestion have triggered research activities for improving spectrum efficiency in wireless cellular networks. Device-to-Device (D2D) communication, which behaves as an underlay to cellular networks and reuses the cellular resources, can relieve the spectrum congestion and achieve throughput enhancement. One major problem that arises with D2D communication is how to coordinate the mutual interference between D2D links and cellular links. Considerable work has shown that with effective resource sharing, D2D communication can significantly mitigate the interference on cellular users. This thesis studies the resource allocation algorithms for D2D communication underlaying cellular networks, which aim to mitigate the interference, extend the application scenario, and improve the quality of service of D2D communication.Firstly, the thesis proposes a Service-Aware Resource Allocation (SARA) algorithm for D2D communication underlaying cellular networks. For a practical scenario with multiple services, there may be different service requirements of D2D users. A traditional resource allocation algorithm may not be able to achieve a good quality of service of D2D communication. In order to solve this problem, SARA takes into account the different service requirements of D2D users. It consists of two allocation phases: on-demand resource allocation and secondary resource allocation. In the first phase, cellular user resources are allocated on demand to meet the different service requirements of D2D pairs. In the second phase, the remaining cellular user resources after the first phase are allocated to D2D users based on an objective function in order to improve the resource utilization. Simulation results show that the proposed SARA algorithm can significantly improve the performance of a cellular system in terms of the satisfaction ratio of D2D pairs and the system throughput.Secondly, the thesis proposes a Time Division Scheduling (TDS) resource allocation algorithm for D2D communication underlaying cellular networks. The proposed TDS algorithm exploits the spectrum resources of cellular users to support more D2D communication. It introduces a time division scheduling framework, in which the scheduling period of a base station is divided into a set of timeslots and the D2D pairs in the system are assigned to different timeslots for communication in a balanced manner in order to accommodate more D2D users in the system. In the D2D pair assignment for each timeslot, it follows a location dispersion principle in order to reduce the interference from D2D users to cellular users and thus increase the system throughput. Simulation results show that the proposed TDS algorithm can significantly improve the system performance in terms of the system throughput and D2D user satisfaction ratio of a cellular system.Finally, the thesis proposes an Adaptive Time Division Scheduling (ATDS) resource- allocation algorithm for D2D communication underlaying cellular networks. In order to offload the base station, the proposed ATDS algorithm adopts a packet scheduling algorithm for a period of time without a frame boundary, which allows D2D users to access the cellular resources according to the priority order in their scheduled timeslots. During the time division scheduling process, the classic proportional fair algorithm is improved according to the characteristics of the resource allocation for D2D communication. The improved proportional fair algorithm can determine the scheduled D2D users in the current timeslot based on the calculated scheduling priority of D2D users adaptively. Simulation results show that the proposed ATDS algorithm can support more D2D users in the cell. Meanwhile, it can significantly improve the quality of service for D2D users and the fairness of the resource allocation.