Effects of diversity on the sum rate of a multiuser M-FSK system over fast Rayleigh fading channel

This paper shows how spatial diversity affects multiuser system rate when a multilevel frequency shift keying modulation signal is transmitted over a fast Rayleigh fading channel with additive white Gaussian noise. No specific multiple access method is used. The channel’s short coherence time precludes the system from estimation or tracking channel parameters. Results show that, in this situation, transmitter diversity is ineffective while receiver diversity has a considerable influence on system rate, as well as increasing the optimum number of users that can share the channel at the same time. It is also shown that in this scenario spectral efficiency can be improved by increasing the number of frequency slots, in opposition to the single user Gaussian noise case.