Advances in modem technology since V.32/V.32bis

There have been significant improvements in modem technology since the development of CCITT Recommendation V.32. These improvements have been not so much in the basic performance/complexity characteristics of TCM as in reduced constellation expansion, robustness to nonGaussian impairments, suboptimal decoding methods, shaping gain, and combined equalization and coding. In addition, the PSTN has improved quite noticeably, and DSP computational power has dramatically increased. In combination, these factors will make possible V.fast modems that can transmit reliably at data rates up to twice as fast as V.32bis modems over the PSTN