Energy efficient transmission and optimal relay location for two-way relay systems

Energy efficiency is an important issue for the future network since the stemming requirements of the ubiquitous access and the limited battery of the mobile devices. In this paper, we investigate energy efficient transmission for two-way relay network. Theoretically, we derive the optimal transmission data rate, which minimizes the total energy consumption per information bit. The energy efficiency region for two-way relay systems is also investigated to illustrate the effects of relay locations on the energy efficiency of the system, and the optimal relay location is also found to maximize the energy efficiency. Numerical results are presented to demonstrate the tradeoff between energy efficiency and the spectral efficiency.