  The process of turbo-code decoding starts with the formation of a posteriori
probabilities (APPs) for each data bit, which is followed by choosing the
data-bit value that corresponds to the maximum a posteriori (MAP) probability
for that data bit. Upon reception of a corrupted code-bit sequence, the process
of decision making with APPs allows the MAP algorithm to determine the most
likely information bit to have been transmitted at each bit time.
