16-ary QAM system for low-data-rate satellite services

This letter introduces a new, simple, flexible and low-cost 16-ary QAM system for low-data-rate satellite services. The modulator uses a look-up table technique which incorporates a spectral shaped filter and a baseband predistortion circuit capable of compensating for both the AM-AM and AM-PM distortions introduced by a nonlinear high-power amplifier (HPA). The symbol error probability (SEP) of the system proposed in the presence of additive white Gaussian noise (AWGN) is evaluated using a semianalytical method. Also, the paper compares the performance of the system to that of a conventional 16-ary QAM with phase-compensating receiver.