LAUSR

In the fifth-generation (5G) of the wireless communication systems, the millimeter wave (mmWave)-based device-to-device (D2D) communication is a promising technique to boost the end-to-end capacity. However, the well-known blockage and high path loss problems of the mmWave severely restrict the reachability of the D2D communication. Therefore, the relaying transmission scheme becomes a necessary component to complete the puzzle of the technologies for 5G. In this paper, we aim to boost the energy efficiency (EE) of the full-duplex relay-aided mmWave D2D communications. To achieve this goal, the nonlinear fractional programming-based iterative power allocation algorithm is first developed to optimize the EE. Then, on top of it, the bottle-neck effect elimination power (BEEP) adjusting method is proposed to further reduce the transmission power while maintaining the end-to-end capacity. By combining these techniques with the properly designed matching algorithm, we propose the EE relaying with the BEEP (BEEPER) algorithm. Via the simulation results, the superior performance of the BEEPER algorithm is verified.