Quasi-gray coding scheme for a (3×22m'+1)-ary QAM with two-time dimensions

As the conventional QAM has a square constellation, PAPR is high due to the corner signal points. To overcome this, the (3 × 2^m)-ary QAM with even m was proposed recently. For odd m, the rectangular constellation has high PAPR and perfect Gray code, while the diamond constellation has low PAPR and imperfect Gray code. In this paper, we propose a scheme assigning quasi-Gray code to the diamond constellation for the QAM with two-time dimensions and provide its generating equation which reduces the hardware complexity. Numerical results show BER performances for the AWGN and Rayleigh fading channels and that the diamond constellation has the lowest PAPR.