Adaptive lattice equalizer to compensate nonlinearities of digital radio channels with MPSK modulation

In this paper we're analyzing performance of adaptive equalization of lattice structure to compensate nonlinearities of digital radio channels with MPSK modulation (satellite channels) with AWGN (additive white Gaussian noise). The nonlinearities are outperformed by TWTA AM/AM and AM/PM nonlinear characteristics. We simulated fifth-order polynomial approximation optimized under minimax criterion (Karam and Sari). In the receiver we simulated : a) DFE (Decision Feedback Equalizer) with FSE T/2 feedforward part with 64 tap adjustment and Symbol Spaced backward part with 32 Lap adjustment b) nonlinear adaptive equalizer proposed by Benedetto and Biglieri with 22 linear and 81 nonlinear tap adjustment ( based on the Volterra series for nonlinear systems with memories) c) adaptive Lattice equalizer (linear structure) with 11 tap adjustment. Simulation results are outperformed with 8PSK and 32 PSK modulations for digital radio system. New is that we found that adaptive lattice equalizer is capable to compensate nonlinearities of digital radio system very successfully ("naturally" without any additional tap adjustment as a consequence of solution of Yule-Walker equation). Adaptive lattice equalizer is giving the better results ( in the sense of Mean Square Error-MSE and convergence rate) in order with equalizers simulated in a), b), but with great reducing complexity. Tills is the main contribution of this paper.