Energy-efficiency region for multiple access channels

To investigate the trade-off between energy efficiency (EE) and spectral efficiency (SE) for Gaussian multiple access channels (MACs), a novel concept of the EE region is developed. The EE region for the time division multiple access system is also derived and compared. The SE-EE trade-off order is introduced to explicitly describe how fast the EE decays with SE in the high SE region. For a symmetric MAC, a constraint on SE-EE trade-off orders is derived and the Pareto optimum can be achieved by the corner points on the EE region.