Pre- and post-cursor intersymbol interference cancellation in nonlinear satellite channels

Abstract

In this paper, we discuss an algorithm for mitigating the deleterious effects of nonlinear intersymbol interference (ISI) in nonlinear satellite channels. We call this algorithm the RAM-search/Viterbi detector (RS-VD) algorithm because it borrows the idea of employing a random-access memory (RAM) from RAM-DFE, it involves search, and it is incorporated into the Viterbi detector. The RS-VD algorithm has been devised to mitigate both precursor and postcursor (nonlinear) ISI. It also mitigates the error propagation problem that arises in making feedforward decisions (for precursor terms) in ISI cancellers used in combination with partial-response signaling. Simulation results indicate that the proposed algorithm achieves a significant performance improvement over the no-equalization case. Similar positive results are expected regardless of the nonlinearity involved as the RAM can model, via training, the nonlinearity of arbitrary nonlinear channels.