Postdetection switch-and-stay combining in Nakagami-m fading

In two recent papers (Alouini and Simon (2003), Simon and Alouini (2003)), the performance of dual branch post-detection switch-and-stay combining (SSC) for noncoherent binary orthogonal frequency-shift keying (BFSK) and noncoherent M-ary orthogonal frequency-shift keying (MFSK) operating in the present of slow flat fading modeled by Rayleigh, Nakagami-m, and Rician distributions have been analyzed. This paper shows that the previous analyses of BFSK and MFSK with postdetection SSC in Nakagami-m fading, which was limited to integer values of m, are incorrect and we derive correct bit error rate performance results for BFSK and MFSK with dual-branch SSC in Nakagami-m fading for all values of m. Our analytical results are verified using extensive Monte Carlo simulations. It is shown that for a given bit error rate the performance gain of postdetection SSC over predetection SSC has been overestimated by several dB in SNR in previous reported work.