Adaptive Nonlinear Compensation of Satellite Transponder Distortion for High-Level Data Modulations

The diffusion of wideband satellite services, especially in the field of digital TV broadcasting and/or interactive multimedia, suggests the adoption of spectrally-efficient high-level modulation techniques in future satellite transmission standards. It is known that such modulations suffers from nonlinear distortion due to amplification with on-board (nonlinear) high-power amplifiers, so that countermeasures are to de adopted in this respect. The aim of this contribution is to investigate the possibility to adopt a suited mixture of adaptive data predistortion (DP) at the transmitter and adaptive nonlinear equalization (NLE) at the receiver to counteract nonlinear distortion at best. In particular, we show that the sensitivity to nonlinear distortion of 16QAM and 64QAM is greatly reduced by clever use of both techniques, and that such an arrangement provides non-negligible (though smaller) performance improvement when using the optimized 16APK constellation recently introduced by ESA, and its extended 64-point version.