Fast iterative coding techniques for feedback channels

A class of capacity-achieving, low-complexity, high-reliability, variable-r ate coding schemes is developed for communication over discrete memoryless channels with noiseless feedback, Algorithms for encoding and decoding that require computations growing linearly with the number of channel inputs us ed are developed. The error exponent associated with the scheme is shown to be optimal and implies that capacity is achievable. Simulations are perfor med and support the analytically predicted high performance and low complex ity.