Paul Marie Pierre Spruyt

A method to reduce the probability of clipping in DMT-based transceivers

A new method allowing a reduction in the probability of clipping in discrete multitone (DMT)-based transceivers is described. The method does not use any kind of precoding and can easily be implemented within conventional DMT-transceivers. The main advantage of the proposed method is an improvement of system performance in terms of overall signal-to-noise ratios (SNRs): with the simplest implementation option of the proposed method, up to about 8 dB improvement in the SNR as compared with previously reported brute force clipping methods can be achieved.

A CMOS analog front-end circuit for an FDM-based ADSL system

A CMOS analog front-end circuit for an FDM-based ADSL system is presented. The circuit contains all analog functions including AGC amplifiers, continuous-time band pass filters, /spl Sigma//spl Delta/ AD/DA converters, and digital decimation and interpolation filters. On-chip automatic tuning of the bandpass filters provides more than 300% center frequency range with 1% frequency accuracy. The higher-order /spl Sigma//spl Delta/ AD/DA converters achieve 12-b data conversion at 1.54 Msamples/s with an oversampling ratio of only 32. The 0.7 /spl mu/m CMOS circuit measures 65 mm/sup 2/ and consumes 1.9 W from a single 5 V power supply.

Adapted optimization criterion for FDM-based DMT-ADSL equalization

The ANSI T1E1.4 Committee finalized the standardization of the asymmetric digital subscriber loop system and the usage of discrete multitone modulation as the ADSL line coding scheme. In order to separate the upstream channel from the downstream channel, the committee accepted two approaches as vendor options: echo cancellation and frequency division multiplexing. We illustrate the impact of the FDM approach on the equalization problem. The unsatisfactory performance of formerly known algorithms is described. A new, simple and near-optimal equalization optimization criterion that is an FDM-based DMT-ADSL is proposed.