Generalized area spectral efficiency: An effective performance metric for green wireless communications

Area spectral efficiency (ASE) was introduced as a metric to quantify the spectral efficiency of cellular systems. Unlike other performance metrics, ASE takes into account the spatial property of cellular wireless system. In this paper, we generalize the ASE metric for arbitrary wireless transmission. Specifically, we introduce the concept of affected area, based on which we evaluate the spectral and power efficiency of three different transmission scenarios, namely single user point-to-point transmission, two-user X channel transmission and two-hop relay transmission. We derive the closed-form expressions of resulting generalized ASE (GASE) metric for each transmission scenario over Rayleigh fading environment. We show through mathematical analysis and numerical examples that there is an optimal choice of transmitting power value in terms of maximizing the area spectrum efficiency.