Resource Allocation for Cooperative D2D Communication Networks

Device-to-device (D2D) communications technology is currently being investigated as a potential enabler for the fifth generation (5G) communication networks. Significant performance gains are achievable in a cooperative D2D framework, wherein the user equipments (UEs) cooperate with each other to enable a variety of low-latency proximity-based services or to establish indirect communication links with the Base Station (BS) whenever direct service coverage is not possible. This chapter is focused on the throughput gains achievable in the latter scenario, i.e., when few UEs perform relaying operations to provide indirect service coverage to other UEs. In this direction, resource allocation problems are formulated for a variety of system models operating under the orthogonal frequency division multiple access (OFDMA) cellular or cognitive radio (CR) access architectures. The performance of mobile D2D relaying under different scenarios is evaluated. The system models are designed to study the benefits of incorporating additional capabilities at the devices, such as packet storage (using buffers), energy-harvesting, and cognitive spectrum access within the cooperative D2D framework. Depending on the system model, efficient algorithms are proposed to obtain optimal power allocation, subcarrier assignment, subcarrier pairing, and relay-UE selection policies which maximize the system throughput under a variety of system-dependant constraints. Simulation results demonstrate the effectiveness of our proposed algorithms and the performance improvement of mobile D2D-relaying networks over conventional networks.