Area Spectral Efficiency Of Infrastructure Relay Enhanced Cellular Systems

In this study, the authors investigate the downlink area spectral efficiency (ASE) of infrastructure relay enhanced cellular systems. ASE for cellular systems is defined as the maximum achievable data rate per unit bandwidth per unit area supported by a base station. In relay enhanced systems, ASE can serve as an attractive performance metric by capturing the benefit of the relatively smaller spatial footprint of relay transmission and the resulting lower co-channel interference. In this study, by applying a moment generating function based approach, the authors first derive the general closed-form statistics of the total interference from dominant co-channel cells over Rayleigh fading channels. These interference statistics are readily applied to the calculation of the resulting ASE. The authors also propose a novel in-cell frequency reuse scheme to further exploit the smaller transmission power of relay stations (RSs). Through selected numerical examples, the authors show that in relay enhanced systems, the cell size, transmission power and RS positions should be properly selected to gain better ASE performance than the conventional systems without relays.