Approaching the Shannon Limit: theorist's dream and practitioner's challenge

Nearly half a century after Shannon established the channel capacity of a noisy channel as the insurmountable limit on the rate of reliable communication, a combination of long known but dormant concepts and a fresh approach has brought us to within a remarkably small distance of that limit. For an additive white Gaussian (AWGN) channel, low error probabilities have been achieved at rates greater than eighty percent of capacity, or in terms of bit energy-to-noise density ratio, E/sub b//N/sub 0/ within less than 1dB of the minimum value which corresponds to operation at channel capacity.