Switched diversity on Nakagami channels

The authors analyze the performance of a switched diversity system operating on nonselective Nakagami fading channels. The analysis is based on a discrete time model, i.e. one switches only at discrete instants of time t=nT, where n is an integer and T is the symbol duration. They propose the following switch-and-stay strategy. Assuming a two-branch diversity system and that antenna 1 is being used at t=(n-1)T, one switches to antenna 2 at t=nT if the local power on antenna 1 at t=nT is below a predetermined threshold value, regardless of the local power in antenna 2 at t=nT. Switching from antenna 2 to antenna 1 is done in a similar manner. They derive expressions for the average bit error rate (BER) using noncoherent frequency shift keying (NCFSK) on slow, nonselective Nakagami (1960) fading channels. Both the cases of independent and correlated diversity signals are considered. The performance depends on the switching threshold chosen. They derive closed form expressions for the optimum switching threshold which minimizes the average BER. The results for a Rayleigh fading channel are obtained and presented as a special case of the more generalized fading models