Capacity of an FH-SSMA system in different fading environments

The capacity of a previously proposed frequency-hopped spread-spectrum multiple-access system (FHSSMA) is evaluated under three types of fading, namely, Rician, shadowed Rician, and Nakagami fading. The results of experiments have indicated that these fading phenomena occur in various environments, where the FH-SSMA system may be implemented. This paper presents the derivation of the deletion probability for each type of fading and analyzes the system capacity in terms of the maximum number of users versus the average bit-error rate (BER). The effect of a change in the signal-to-noise ratio (SNR) level on the system capacity is also demonstrated. For Rician fading, we find that the capacity of the system with a Rician factor of 2 dB is reduced by 13% as compared to the capacity for the nonfading case. For shadowed Rician fading, three shadowing scenarios are considered: light, average, and heavy. It is shown that the light and average shadowing scenarios provide only a slight decrease in the capacity, while the heavy shadowing scenario renders a capacity identical to that for the Rayleigh fading case. Finally, for Nakagami fading, the capacity is found to decrease by 50% as the fading parameter is reduced to 0.5.