A survey on relay selection in cooperative device-to-device (D2D) communication for 5G cellular networks

Device-to-device (D2D) communications underlay to a cellular infrastructure has recently been proposed to increase spectrum efficiency and expansion of coverage. Relay selection plays an important role in cooperative networks. In D2D communication, if the chosen relay is not the best relay, then the whole communication will not be successful from source node to destination node. Also to choose the optimal relays, if more feedback and time delay exists between source and relay nodes then it leads to degradation of spectral efficiency. A survey on the relay selection techniques suitable for D2D communication in 5G cellular network is presented.