Abstract
The present work is aimed towards an analysis of the ITU-T V.90 standard. Functionally, the system is divided into three main areas: Constellation Design, Spectral Shaping, and Detection. A signal constellation design algorithm is presented with a very simple structure and very good performance characteristics. The spectral shaping technique used was found to be a version of the LABI; its performance was evaluated by simulation. When working with detection, a hybrid solution between Decision Feedback Equalization (DFE) and Maximum Likelihood Sequence Estimation (MLSE) was developed. The main advantage of this hybrid scheme is that it allows the user to customize the complexity of the decoder to suit requirements of each particular application. Simulation results showed improvements in performance over DFE, particularly in channels with severe distortion levels.
Caraballo, Luis Martin (2000). System level design and simulation of a PCM voiceband modem compliant with the ITU V.90 standard. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -2000 -THESIS -C368.