In this paper, the authors introduce a new metric, namely, Effective Area Spectral Efficiency (EASE), to quantify the spectral efficiency as well as the spatial properties of point-to-point transmission systems and Decode and Forward (DF) relaying communications networks with interference management. For each transmission mode, they derive a closed-form expression for the maximum transmission range under Rayleigh fading environment. Based on the maximum transmission range, they define and derive the average affected area and the average ergodic capacity.