Asymptotic System Performance over Generalized Fading Channels with Application to Maximal-Ratio Combining

Abstract

The performance of wireless communications systems is affected by many aspects of the fading phenomenon, such as clustering, nonlinearity, scattered waves, and line of sight. Even though several fading models exist which address a multitude of propagation conditions, in many cases the fading statistics or the associated system performance cannot be obtained in a closed form. In such cases, it is difficult to decipher how each physical aspect of fading impacts the system performance. In this work, we propose a unified asymptotic characterization at high signal-to-noise ratio to obtain simple, general closed-form expressions for the diversity and coding gains of essential performance metrics, namely, symbol error rate and outage probability. We cover generalized propagation conditions and all the referred fading aspects. The analysis is further extended to investigate the performance of multibranch maximal-ratio combining. Capitalizing on the fact that the asymptotic channel distribution around the origin fully determines the diversity and coding gains, our results provide new insights into how each physical aspect of fading ultimately affects the wireless system performance.