Relay Selection for Spectral-Efficient Network-Coded Multi-Source D2D Communications

In the 5th generation (5G) of cellular networks, users can directly communicate together without the need for macrocell base station (MBS) which is referred to as device-to-device (D2D) communication. Future cellular networks are ultra-dense heterogeneous networks (HetNets) which include macrocells and several small cells such as picocells and femtocells are more efficient in indoor environments. Network coding in cooperative communications can extend the D2D communication coverage area and increase data transmission rate. Relay selection plays an important role in cooperative communications. Since user equipment has a limited energy source, i.e., battery, femtocell base station (FBS) can act as a relay and cooperate in D2D communication. The purpose of this article is to present an efficient method for relay selection among femtocell for multi-source network-coded cooperative D2D communication in order to improve the spectral efficiency. Several trees are created to consider all transmission scenarios and then the optimum transmission scenario is selected. The results show that the proposed method can improve the outage probability and spectral efficiency of multisource D2D communication.