Survey on device-to-device communications: Challenges and design issues

Device-to-Device (D2D) communications has been proposed to cellular networks in order to optimize spectrum efficiency and resources utilization. In D2D-assisted networks, the traditional cellular communication techniques are not applicable but rather need to be redesigned to fulfill new requirements. Therefore, new communication techniques are proposed to take the advantages of the D2D connectivity in the network. In this paper, we describe the concept of D2D communications. Then, we review the main challenges and design issues of D2D-assisted networks. This survey focuses on cooperative communications in D2D-assisted networks and addresses challenges which limit the performance of the cooperative D2D-assisted networks such as relay selection, power consumption and multi-casting. Moreover, design issues and approaches to overcome these limitations are explained.