On the Design of Robust Orthogonal Adaptive Decision Feedback Equalizers for Uncertain Dispersive Channels

This paper presents the theoretical aspects of a methodology for the design of robust orthogonal adaptive decision feedback equalizers. The dispersive transmission channel is assumed to have a transfer function type of description with small uncertainties in the parameters. A decision feedback equalizer is designed minimizing a mean square error objective function that takes into account the uncertain description of the channel. The equalizer is conceived with an orthogonal basis structure, so that the basis parameters inherit the robustness properties of the design to parameter perturbations. Adaptation of the coefficients that linearly combine the basis elements is also considered and the development of the adaptation algorithm is included. The resulting equalizer has a very flexible, modular and easy to implement structure. An example with comparisons of performance with FIR designs is included. Keywords— Communications, Uncertainty modeling, Equalization, Robust Filtering