Coding in a discrete multitone modulation system

Discrete Multitone (DMT) modulation is a multicarrier technique which makes efficient use of the channel, maximizing the htroughput by sending different numbers of bits on different subchannels. The number of bits on each subchannel depends in the Signal-to-Noise Ratio of the subchannel. The performance of a DMT system can be further increased by using powerful coding techniques. This thesis investigates an implementation of coding for a DMT system. The coding techniques considered are Ree-Solomon coding combined with interleaving, and Trellis Coded Modulation. Wei's 4-dimensional 16-state coder combined with trellis shaping is the suggested trellis code. A single encoder is used which codes across the tones of each DMT-symbol. At a bit error probability of 10 -7 the suggested codes gain 3-6 dB over uncoded transmission. Hardware complexity and algorithmic aspects of coding are covered, as well as simulations to verify it