Nonlinear equalization structure for high-speed ADSL in ideal and non ideal conditions

The ADSL G.DMT technology, based on discrete multi-tone (DMT) modulation, employs an equalization structure consisting of a time-domain equalizer (TEQ) and a frequency-domain equalizer (FEQ). These two complementary systems allow good immunity against inter-symbol interference (ISI), to improve the bit error rate while optimizing the throughput. In literature, some of these equalization structures are proposed, but they are usually tested in ideal conditions; with perfect knowledge of channel characteristics and with linear channels. In this paper, we present a TEQ and a FEQ designed for non ideal transmission conditions, while keeping with the technology requirements. A nonlinear TEQ based on neural network structure is proposed to attenuate the interference due to the non ideal conditions.