New analytical expressions for probability of error for classes of orthogonal signals in Rayleigh fading

New exact expressions for symbol error rates (SER) and bit error rates (BER) for coherent 3-ary and 4-ary orthogonal and transorthogonal signaling in slowly fading Rayleigh channels are derived. New exact error probability expressions for coherent 6-ary and 8-ary biorthogonal signaling in slow Rayleigh fading are also presented. The use of these exact expressions as close approximations for the error rates of M-ary orthogonal, biorthogonal and transorthogonal signaling with arbitrary M is illustrated.