Consider an M-ary constellation with the ith symbol denoted by ,. Let the probability of , be P.. The average power of this constellation is given by: M Pav =E l, P. (2.82) i=1 Consider now a translate of the original constellation, that is, all symbols in the constellation are shifted by a complex constant . Note that the probability of symbol error remains unchanged due to the translation. The average power of the modified constellation is given by: M Pay =E l, a P,