MODULATION AND CODING FOR LINEAR GAUSSIAN CHANNELS

Shannon's determination of the capacity of the linear Gaussian channel has posed a magnificent challenge to succeeding generations of resear chers. This paper surveys how this challenge has been met during the p ast half century. Orthogonal minimum-bandwidth modulation techniques a nd channel capacity are discussed Binary coding techniques for lo low- signal-to-noise ratio (SNR) channels and nonbinary coding techniques f or high-SNR channels are reviewed. Recent developments, which now allo w capacity to be approached on any linear Gaussian channel, are survey ed. These new capacity-approaching techniques include turbo coding and decoding, multilevel coding, and combined coding/precoding for inters ymbol-interference channels.