Energy efficient hybrid one-way and two-way relay transmission strategy

In this paper, we design energy efficient relay transmission strategy in a system where two source nodes transmit to each other assisted by an amplify-and-forward relay node. We first compare the energy efficiencies (EEs) between one-way relay transmission (OWRT) and two-way relay transmission (TWRT), which shows that when the bidirectional data amounts are equal, TWRT performs better, otherwise, OWRT may offer higher EE. To achieve the maximal EE in various settings, we propose hybrid relay transmission (HRT) that transmits partial messages with OWRT and the remaining messages with TWRT, and jointly optimize the data amounts and transmission time allocated to the OWRT and TWRT parts. Simulation results show the superiority of the HRT over both OWRT and TWRT.