BER of BFSK with Postdetection Switched Combining in Correlated Rayleigh Fading

The performance of binary frequency-shift keying (BFSK) with dual-branch postdetection switch and stay combining (SSC) in correlated Rayleigh fading is considered. A closedform expression for the average bit error rate (BER) of BFSK with dual-branch postdetection SSC is derived. Optimum switching thresholds that minimize the average BER are obtained. It is shown that, for a fixed value of average signal-to-noise ratio (SNR), the optimum switching threshold is a decreasing function of branch correlation. Our analytical results are validated using Monte Carlo simulation results. The performance of dual-branch postdetection SSC is compared to the performance of dual-branch predetection SSC in correlated Rayleigh fading and it is shown that postdetection SSC has superior performance over predetection SSC for all values of SNR.