On the Chandra–Poram–Bose symbol error probability expression for coherent orthogonal M ‐ary frequency shift keying

SUMMARY An expression for the average symbol error probability of coherent orthogonal M ‐ary frequency shift keying in generalized fading was recently reported by Chandra, Poram, and Bose. We show that the expression is only exact for M  = 2; it does, however, provide an accurate approximation for M  > 2. By modifying the derivation of the reported expression, we derive a lower bound for M ⩽ 5 that has the same complexity as the reported expression, and we illustrate that, for M  > 2, the expression of the derived bound provides an approximation that is also more accurate.Copyright © 2012 John Wiley & Sons, Ltd.