A Study On Dynamic Resource Allocation Mechanisms For Device-to-Device Communication Underlaying Cellular Networks

With the number of mobile devices increasing continuously and the rapid development of the mobile Internet, the demand for mobile communication service is increasing rapidly. However, the spectrum resources for cellular communication is limited, and is becoming more and more scarce. In order to improve the spectrum utilization, the concept of Device-to-Device (D2D) communication has been proposed in recent years. By employing the D2D communication technology, we can improve the spectrum utilization, increase the system capacity, and reduce the load of a base station for a cellular network. However, as D2D communication may reuse the spectrum resources of cellular communication, it may cause severe interference between D2D communication and cellular communication. Resource allocation is an effective technique to mitigate the interference between D2D communication and cellular communication. Therefore, resource allocation has become an important research area in the area of D2D communication.Until now, most study on the resource allocation problem in D2D communication concentrates on static system scenarios. In the real world, however, mobile users arrive in and leave a cellular system dynamically. How to allocate spectrum resources for mobile users in a dynamic system scenario becomes an key issue in D2D communication.This thesis studies the dynamic resource allocation problem in D2D communication underlaying cellular networks. It proposes two dynamic resource allocation mechanisms for the D2D communication, i.e., a service time based dynamic resource allocation mechanism and a dynamic resource allocation mechanism for multi-hop D2D communication. The service time prediction based dynamic resource allocation mechanism introduces the concept of "utility" to reflect the performance of the system. Meanwhile, it considers different service types and the service time or remaining service time of a user in the spectrum resource allocation. Specifically, it enables the BS to predict the service time of a new user and the remaining service time of existing users in the system, and takes into account the predicted service time and remaining service time in calculating the effective utility gain caused by the arrival of a new user. Based on the calculated effective utility gain, the BS will select the physical resource block (PRB) with the largest effective utility gain every time it allocates a PRB to the new user. Simulation results show that the proposed dynamic allocation mechanism can significantly improve the system performance in terms of the system capacity as compared with a random resource allocation mechanism without service time prediction.To further improve the system capacity, this thesis proposes a dynamic resource allocation mechanism for multi-hop D2D communication. This allocation mechanism allows two users within a certain distance to establish D2D communication using some idle user as a relay. Unlike existing work, this allocation mechanism considers the impact of the activity degree of a relay user on the resource allocation for multi-hop D2D communication because the status of the relay user would directly affect the connectivity of the multi-hop communication. When a pair of new active users request for communication with the BS, the BS will calculate all possible effective utiltiy gains, and then select the PRB with the largest effective utility gain and allocate the PRB to the pair of new active users. Simulation results show that the proposed dynamic allocation mechanism can further improve the system performance as compared with the allocation mechanism which only allows one-hop D2D communication. When the density of mobile users is larger, this allocation mechanism can provide better system performance.