S plus N-ESC diversity in Nakagami and Rician fading with MPSK and 16-QAM

A signal-plus-noise (S + N) energy selection diversity combining (S + N-ESC) scheme for M-ary phase shift keying (MPSK) and 16-quadrature amplitude modulation (16-QAM) signaling in Nakagami-m and Rician fading channels is studied. The S + N-ESC selects the branch with the maximum S + N energy for detection. The advantage of the S + N-ESC scheme is that it requires no explicit channel estimation for diversity branch selection. We show that the symbol error probability (SEP) of the S + N-ESC is the same as that of classical selection combining (SC) for MPSK signaling in independent and identically distributed (i.i.d.) Rayleigh fading channels. Also, we show that the SEP of a weighted S + N-ESC scheme is the same as that of classical SC for MPSK signaling in independent and nonidentically distributed (i.n.d.) Rayleigh fading channels. It is shown that the S + N-ESC scheme provides a smaller SEP than classical SC for MPSK signaling in nondispersive fading channels such as Nakagami-m fading channels with Nakagami parameter m > 1 and Rician fading channels with Rician parameter K > 0. On the other hand, the S + N-ESC scheme is shown to have a larger SEP than classical SC for 16-QAM signaling in Nakagami-m and Rician fading channels.