In this letter, we present a noncoherent coded 16QAM (NC-16QAM) scheme by m
odifying the trellis-coded 16QAM (TC-16QAM) scheme. Our simulation results
show that the performance of the NC-16QAM with noncoherent detection is clo
se to the one of the original TC-16QAM with coherent detection. The NC-16QA
M in this letter is an extension of the NC-8PSK recently obtained by Wei an
d Lin. A noncoherent initial phase estimation algorithm is also proposed.