Energy-efficient relay selection and power allocation for multi-source multicast network-coded D2D communications

Device-to-device (D2D) communication improves spectrum efficiency (SE) and increases system capacity. Heterogeneous networks comprise macrocell and several small cells, such as picocells and femtocells, where femtocells are more efficient. In cooperative communications, one or several additional nodes help to send data from source to destination to improve the quality of service (QoS). Network coding (NC) in cooperative networks can extend data rate and coverage area of D2D communication. The purpose of this article is to minimize power consumption of transmitting nodes during network-coded cooperative D2D transmission to reduce the interference on co-channel transmissions. In this study, we consider cooperative multicast D2D communication with NC, where femtocell base stations (FBSs) are used as relay. We propose a method based on energy efficiency (EE) maximization for relay selection and power allocation for multi-source network-coded cooperative D2D communication in heterogeneous cellular networks. We present a solution to the proposed method and evaluate its performance. The results show that the introduced method significantly improves the SE and EE compared to the coordinated multi-point (CoMP) transmission, multi-source direct D2D communication (D-D2D), and other works.