An Adaptive Equalizer to Reduce the Nonlinear Distortion Effects in Satellite Broadcasting Systems

This article presents the BER performance improvements achieved when adopting Adaptive Equalization based on Decision Feedback Equalizer (DFE) to tackle the negative effects of nonlinear distortion in the receiver performance, caused by the Traveling Wave Tube Amplifier (TWTA), in a satellite receiver devoted to broadcasting. We have evaluated the performance for the DVB-S2 modulations, but the proposed DFE can be easily extended to be used in DVB-S2X systems. In our previous work we have presented the performance gains when using the same DFE to tackle the Inter-Symbol-Interference (ISI) caused by the Land Mobile Satellite Channel (LMSC). In that work, we have presented prototyping results in FPGA targeting a ASIC implementation. In this work we also investigate the performance improvements of the proposed DFE to tackle the effects of the nonlinearity combined with the ISI. The simulations results have shown that the proposed equalizer is capable of bringing significant performance improvements in both cases, i.e pure nonlinearity and nonlinearity combined with ISI, specially for the higher order modulation. It is worth mentioning that our proposal does not deal with the out-of-band spurious emissions caused by the nonlinear distortion, which needs to be handled by an appropriate technique such as predistortion.