Is training of adaptive equalizers still useful?

Abstract

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Adaptive decision feedback equalization: can you skip the training period?

“…The transfer functions and are anticausal. As a consequence, the implementation of (4) requires a delay and a transversal filter , with TF (5) where TSE stands for "truncated series expansion" of order , in terms of the positive powers of Moreover, the filter can itself be split into a , a , and a transversal filter as in [8] and [9]. Thus, up to a delay, the optimal LE takes the cascaded form (6) Clearly, the order of the four linear transformations , , , and is irrelevant in steady state.…”

“…The basic idea of the cascade is to split the difficult task of unsupervised equalization into several, but easier, subtasks. Furthermore, the structure itself is made adaptive and a performance index-the estimated MSE-is used to select the appropriate structure and its adaptation [8], [9]. The unsupervised starting period begins with before Once the eye is open, this equalizer is switched into a classical DFE simply by placing after and introducing the detection device into the recursive path of Adaptation is then pursued in the classical DD mode.…”

A novel blind equalization structure for deep null communication channels

“…A similar technique has been independently developed in [4] where the required all pass filter is approximated by an FIR filter and the positions of the IIR filter and the FIR filter is reversed. In order to analyse our new structure, let the transfer function of the combined channel and the IIR filter, that is an all pass filter, be in which ho = 1 and n, is the order of the all pass filter.…”