Techniques for generating soft values for parity bits in a convolutional decoding process are disclosed. An exemplary method comprises, for each of at least one iteration in at least one soft-input soft-output decoder, calculating intermediate probability values for each possible transition between a first plurality of candidate decoder states at a first time and a second plurality of candidate decoder states at a second time. Two or more partial sums are then computed from the intermediate probability values, wherein the partial sums correspond to possible combinations of two or more systematic bits, two or more parity bits, or at least one systematic bit and at least one parity bit. Soft values, such as log-likelihood values, are then estimated for each of at least one systematic bit and at least one parity bit of the received communications data corresponding to the interval between the first and second times, based on the partial sums.