Objective: The progress of electronic warfare and the possibility of eavesdropping reveal the necessity of establishing direct communication between operational forces on the battlefield. Recently, device-to-device (D2D) communication has been introduced to establish direct communication between users, in which pairs of users can directly exchange data with each other. However, with the increase in the number of pairs, the interference increases, the quality of service decreases, and there is a need for relay nodes to cooperate in D2D communication.

Methodology: In this paper, we consider the data transmission system of several pairs in D2D format, where intermediate nodes, or relays, participate in data transmission. Also, due to the energy supply of the devices by the battery, the maximum data transfer should be performed with the minimum power consumption. The purpose of this paper is to provide a new solution for choosing a relay and transmission power control to maximize energy efficiency. In the proposed method, we allow multiple D2D pairs to use the same relay while D2D pairs use the same channel to increase spectrum utilization. To reduce interference, precoding is used to detect transmissions for each D2D pair and increase system capacity. To evaluate the performance of the proposed method, Monte Carlo simulations have been performed in MATLAB software.

Findings: The simulations show that the proposed method improves spectral efficiency and energy efficiency and increases system reliability.

Originality: The results show that the proposed system can be used as a reliable communication system in the battlefield and wargaming simulations.