Output Signal-to-Noise Power Ratio Characteristics in FM Communication Systems with Fading

Abstract

This paper describes the output SNR (Signal-to-Noise Power Ratio) and noise characteristics of the wide-band analog FM communication system in the m-distributed fading environments, where the output noise consists of random noise and click noise.
The improvement effects due to the diversity are also investigated, and three kinds of linear diversity combining techniques, such as Selection Combining (SC), Equal-Gain Combining (EGC), and Maximal-Ratio Combining (MRC), are compared from the viewpoint of the improvement effects including the correlation between two diversity branches.
The main results obtained by the analysis are as follows.
1. The fading affects the click noise more strongly than the random noise.
2. Much more diversity improvements can be obtained in the click noise than in the random noise.
3. The better SNR performance can be obtained for the case with smaller correlation between two diversity branches.
4. The MRC is the best diversity technique.
5. This analysis is also applicable to the case without fading.