Selection of relay UE with energy harvesting capabilities in public safety environment

Relaying is a widely proposed solution for multi-hop communication in PS environments. However, the selected relay is energy constrained and cannot go on indefinitely. Energy harvesting can solve this problem and make multi-hop D2D communication a viable solution for PS services. In this paper, selection of energy harvesting relay has been studied for device-to-device (D2D) communications. Public safety environment has been considered, where some user equipments (UE) are located out of the coverage area of eNodeB (eNB). For out of the coverage UEs, communication with the eNB is possible through an intermediate relay UE and selection of those intermediate relay UEs is the main focus of this work. Based on D2D link between potential relay UE and out of coverage UEs and estimated harvested energy at potential relay UE, a relay UE is selected to support out of coverage UEs. The relay-based approach enables D2D communications to incorporate cellular and ad hoc operations based on the network availability. The energy harvesting parameter at the relay UE make it unique, which is used to extend the life of rapidly drained battery of a relay UE. The effect of energy harvesting and D2D link quality on the selection of a relay UE has been topics of focus in this work. The proposed scheme is evaluated through system level simulations.