Nonlinear equalization for frame-differential IR-UWB receivers

This paper shows equalization approaches for high-data-rate transmitted-reference (TR) IR-UWB systems employing an autocorrelation receiver front-end. Using a maximum likelihood sequence detector (MLSD) with decision feedback (in the back-end of the TR-receiver), a significant improvement of the receiver performance is possible. To avoid the high complexity of the MLSD detector, alternative equalizer structures are evaluated. If the parameters of the channel are not known a priori, an equalizer has to be adapted during the transmission of training data. Such an adaptive equalizer is presented as a reference. Furthermore, we study the design of minimum mean square error (MMSE) equalizers assuming knowledge of the channel. A linear MMSE equalizer is designed using the linear and nonlinear channel coefficients. Then the concept of the linear equalizer is extended to a nonlinear Volterra equalizer which further improves the performance of the IR-UWB receiver structure. All proposed methods are discussed and the effects are shown with computer simulations