Phase Error Analysis of M-QAM Demodulation in Satellite Channel

Multi-level Quadrature Amplitude Modulation is one of the most popular modulation technique in the satellite channel for its spectral efficiency in limited bandwidth communication. The Multi-level Quadrature Amplitude Modulation demodulator performance sensitive to the phase error of the received signal. The demodulator at the receiver is in these estimates, and the sensitivity increases as multi-level increases. The phase error of received signal impacts on constellation diagram and increases bit error ratio. Simulated results in Additive White Gaussian Noise channel and Rayleigh channel show that there are two major factor impact on the phase error: characteristics of environmental communication and the number of level M of quadrature amplitude modulated signal. Specially, phase errors are vigorously affected by fading noise with Doppler shift.