RELAY SELECTION-BASED ENERGY EFFICIENCY OF HYBRID DEVICE-TO-DEVICE-ENABLED 5G NETWORKS

Device to device (D2D) communication is one of the communication methods to be applied to the 5G mobile communication network to improve performance and energy efficiency. However, D2D communication is not effective when the link distance between two mobile devices is far away. Cooperative D2D is one of the solutions to maintain high network performance and increase energy efficiency to overcome this problem. Currently, the cooperative D2D network model focuses on multi-hop relay and multi-relay. Practically, a source can simultaneously transmit information over a multi-hop relay and multi-relay networks to be forwarded to a destination. In this paper, we introduce a hybrid relay network model for a 5G D2D network that uses relay selection strategies to improve energy efficiency. Then, we provide reactive and proactive relay selection procedures for the proposed hybrid relay network. The energy consumption and efficiency are mathematically analysed and simulated for several D2D network configuration models. All simulations are performed using MATLAB 2019a software. The simulation results show the energy consumption using the PRS strategy is smaller than that of using the RRS strategy. At a distance ratio of 0.5, the hybrid relay network using the PRS strategy can save energy by 0.05864 mu J/bit. Furthermore, the hybrid relay networks achieve higher energy efficiency compared to the multi-relay and multi-hop relay networks for both reactive and proactive cases. The proactive strategy achieves 5% higher energy efficiency than the reactive strategy for the hybrid relay networks at a distance ratio of 0.3. Furthermore, simulation results also show that the addition of SNR on the network does not have a significant impact on energy efficiency, although the proposed hybrid relay networks still have better efficiency. Thus, the proposed hybrid relay network using a relay selection strategy can improve the energy efficiency of 5G D2D networks.