We introduce a 16-dimensional constant-amplitude constellation that is generated by concatenating either four constant envelope quadrature-quadrature phase shift keying (CEQ2PSK) symbols from Saha and Birdsall or four CEQ2PSK symbols recently discovered by Cartwright and also introduced here. Our new constellation doubles the number of points available for data transmission without decreasing the distance between points or increasing energy, and may therefore be used in a trellis coded modulation (TCM) system without constellation expansion penalty. Because the new constellation has constant envelope, the modulation scheme becomes very attractive for nonlinear channels such as the magnetic recording channel or the satellite channel with traveling wave tube amplifiers.
Quinteros, M., K. V. Cartwright, E. J. Kaminsky, and R. Gallegos, “A Novel Expanded 16-Dimensional Constant Envelope Q2PSK Constellation,” IEEE Region 5 BASICS2 Technical Conference Proc. (Kansas City, MO), 17-20 April 2008, 4 pp.