Predistorter Design Employing Parallel Piecewise Linear Structure and Inverse Coordinate Mapping for Broadband Communications

M.Y. CHEONG; S. WERNER; T. I. LAAKSO; J. E. COUSSEAU; J.L. FIGUEROA

Florence

Congreso; 14th European Signal Processing Conference; 2006

European Signal Processing Society

This paper proposes a low-complexity predistorter (PD) forcompensation of both the AM/AM and the AM/PM conversionswith memory. The nonlinear power amplifier (PA)is modeled as a Wiener type nonlinearity. The quasi-staticnonlinearities are modeled using a class of piecewise linear(PWL) functions. The PWL function facilitates an efficientPD identification algorithm. The proposed algorithminvolves a novel inverse coordinate mapping (ICM) methodthat maps the nonlinear characteristics of the PA to that ofthe PD, and parameter estimations that do not require matrixinversion. The indirect learning architecture is used to providean on-line compensation of thememory effect of the PA.Simulation results show that the PD that compensates alsothe AM/PM distortion performs significantly better than onethat considers only the AM/AM nonlinearity. The proposedPD is also shown to outperform the orthogonal polynomialPD in both adjacent channel interference suppression and inbanddistortion compensation.