Asymptotic performance of M-ary orthogonal modulation in generalized fading channels

The asymptotic (M to infinity ) probability of symbol error P/sub e/,/sub m/ for M-ary orthogonal modulation in a Nakagami-m fading channel is given by the incomplete gamma function P(m, mx) where x=In 2/(E/sub b//N/sub 0/) and E/sub b/ is the average energy per bit. For large signal-to-noise ratio this leads to a channel where the probability of symbol error varies as the inverse mth power of E/sub b//N/sub 0/. These channels exist for all m>or=1/2. The special case of m=1 corresponds to Rayleigh fading, an inverse linear channel.>