Methods and apparatus for facilitating wireless communication using digital Quadrature Amplitude Modulation are disclosed. A mapping module electronic component of a wireless communication device utilizes a signal constellation for quadrature modulating a signal for transmission or quadrature demodulating a received signal. The signal constellation includes multiple constellation symbols and associated bit sequences. Specific signal constellations are disclosed. The signal constellations may be obtained through an optimization procedure which accounts for both phase noise and power amplifier nonlinearity.