A Study On Resource Allocation Algorithms For Device-to-device Communication In Mobile Cellular Networks

With the rapid development of mobile Internet, more and more mobile devices appear in our daily life, which causes the increasing demand for data transmission. However, the spectrum resources allocated to mobile communication is limited. Thus, the lack of spectrum resources is a problem we are currently facing. Improving the spectrum utilization is an important research topic in wireless resource management. In order to solve this problem, the concept of D2D (Device-to-device) communication underlaying mobile networks has been proposed. Numerous studies have demonstrated that the D2D communication technology can increase the system capacity, improve the spectrum utilization, and reduce the load of base station (BS). As a result, designing an efficient resource allocation algorithm for D2D communication underlaying cellular networks becomes an important research focus.This thesis studies the resource allocation algorithm for D2D communication underlaying cellular networks. For different scenarios and applications, it proposes three resource allocation algorithms for D2D communication:Capacity Oriented Resource ALlocation (CORAL) algorithm, Advanced CORAL (ACORAL) algorithm, and Graph-coloring based resOurce ALlocation (GOAL) algorithm.First, the thesis proposes a Capacity Oriented Resource ALlocation (CORAL) algorithm, which considers a general single-cell scenario where the number of cellular users in the system is much larger than that of D2D pairs. In order to maximize the system capacity, CORAL first introduces the concept of a Capacity-Oriented Restricted (CORE) region for a D2D pair to determine the candidate cellular user set for the D2D pair in resource allocation. Then, based on the CORE region, CORAL algorithm employs a novel two-step allocation method, which can not only ensure that each D2D pair be allocated the resources of at least one cellular user, but also reduce the computational complexity, and maximize the system capacity. Simulation results show that CORAL can achieve a good performance in terms of both the system capacity and the rate loss of all cellular users.The CORAL algorithm cannot achieve a good performance in terms of system fairness in a single-cell scenario where the mobile users are non-uniformly distributed in the system. To improve the fairness in this particular scenario, the thesis further proposes an Advance CORAL (ACORAL) algorithm. Similarly, this algorithm also employs a two-step allocation method. The difference is that ACORAL sets a threshold for each D2D pair which represents the maximum amount of cellular user’s resources allocated to each D2D pair. Simulation results show that the ACORAL algorithm sacrifices the system capacity for the system fairness and, achieves a greater advantage over the CORAL algorithm in the non-uniformly-distributed scenario than the uniformly-distributed scenario.Finally, considering a special single-cell scenario where the number of D2D pairs is larger than that of cellular users, the thesis proposes a Graph-coloring based resOurce ALlocation (GOAL) algorithm. In this algorithm, the D2D pairs in the system are viewed as a set of vertexes and the resources of cellular users are viewed as a set of colors. To support resource allocation, GOAL introduces the concept of the interference negligible distance (INS) to identify those D2D pairs that can simultaneously share the same spectrum resources of cellular users, and the concept of the signal to interference ratio (SIR) limited area (SLA) to identify a set of D2D pairs that cannot share the spectrum resources of a particular cellular user. Simulation results show that the proposed GOAL algorithm can significantly improve the system capacity and accommodate more D2D users.