Vector coding for partial response channels

The authors apply multidimensional trellis-coded modulation schemes to spectrally shaped channels with additive white Gaussian noise. Traditional equalization methods that flatten the channel pulse response incur large losses on channels with severe intersymbol interference (ISI). Using block symbols, vector coding divides the channel into a set of parallel ISI-free channels. By transmitting many codes in parallel, each with a different size signal constellation, the input signal power is redistributed to the subchannels with superior transfer characteristic. The authors examine two different discrete-time channels, the duobinary partial-response channel and a representative twisted-wire-pair local loop. In both cases, they show that vector coding in concert with a good coset code operates near the computational cutoff rate for that channel