Iteration terminating using quality index criteria of Turbo codes

A decoder dynamically terminates iteration calculations in the decoding of a received convolutionally coded signal using local quality index criteria. In a turbo decoder with two recursion processors connected in an iterative loop, at least one additional recursion processor is coupled in parallel at the inputs of at least one of the recursion processors. All of the recursion processors perform concurrent iterative calculations on the signal. The at least one additional recursion processor calculates a local quality index of a moving average of extrinsic information for each iteration over a portion of the signal. A controller terminates the iterations when the measure of the local quality index is less than a predetermined threshold, and requests a retransmission of the portion of the signal.