Spectral efficiency of adaptive coded modulation in urban microcellular networks

This tutorial paper describes a general adaptive coded modulation scheme for airlinks in urban wireless networks. Each airlink is degraded by shadowed Nakagami multipath fading, interference from other airlinks, and signal path loss. An instance of the adaptive coding scheme utilizes a set of trellis codes originally designed for additive white Gaussian noise channels. A model of the worst and best case interference configurations of a fully loaded network is developed to approximate the average link spectral efficiency (ALSE) of an arbitrary instance of the coding scheme. It is then shown why the ALSE of the adaptive coding scheme is larger than the fixed link spectral efficiency of a traditional nonadaptive coding scheme. Moreover, the ALSE approximation is modified to approximate the average area spectral efficiency (AASE) of the network, and how the cellular layout influences the AASE is shown.