Resource Management for D2D Communications in Future Cellular Systems

Recently, with the increasing demand for local traffic, and the steep growth in mobile data traffic has gained a lot of attention. With current infrastructure deployments and radio resources, operators will not be able to cope with the upcoming demands. Consequently, discussions of the next generation of mobile networks, referred to as the fifth generation (5G), have started in both academia and industry. In addition to more capacity, stringent requirements for improving capacity, decreasing outage probability, low delays, low power consumptions and increasing reliability have been envisioned in 5G. Many solutions have been put forward, one of them being Device-to-Device (D2D) communications where Cellular User Equipments (CUEs) can transmit directly to one another bypassing the base station (BS) via uplink (UL) or downlink (DL) paths. In this dissertation, firstly we survey the background of D2D technologies, and a brief comparison of several popular D2D technologies and how they are integrated in cellular networks, possible requirements and challenges of D2D-enabled LTE-A networks. Then, we review the background of LTE-A physical and MAC layer and details of D2D communication in LTE-A. Secondly, we present the architecture of the multi-cell network scenario adopting frequency reuse across different cells, where Inter-Cell Interference (ICC) and Intra-Cell Interference (IACC) are consider, and present the mathematical formulation for SINR, capacity of both CUEs and D2D pairs in underlay and cellular mode. By exploiting frequency reuse, this research work aims to design wireless system level algorithms to utilize the spectrum resources efficiently in the next generation wireless heterogeneous network, where resource allocation and interference management algorithms to significantly improve user experience, system capacity, and avoidance outage probability for D2D communications underlaying wireless heterogeneous networks. A resource allocation for the D2D communications underlaying cellular network is given in this dissertation, which is applied the basic of Round Robin (RR) and Proportional Fair (PF) scheduling, and we also provided some techniques to improve the cell capacity while controlling outage probability in the presence of D2D communications (underlay mode) as RR-FAR, RR-FAR-OUT, PF2 and PF2-OUT, after that we propose a CUE and D2D capacity and outage probability analyze models of both underlay and cellular mode. Finally, the performance of D2D communication underlaying LTE-A system are investigate in a single-cell and multi-cells scenarios via system-level simulation with different settings and compared with other scheduler techniques and cellular mode (CELLM). The simulation results show that considerable performance capacities are achieved by enabling direct D2D data paths to replace conventional uplink (UL) and downlink (DL) data paths for local data traffic between proximate devices, and by allowing non-orthogonal resource reuse between D2D and cellular uplink transmission. The initial tests demonstrate that the proposed scheduling method successfully improves the capacity and mitigates interferences resulting from co-channel interference exists between a CUE and D2D pairs of the cell.