The BCJR algorithm is an algorithm. It is characterized by convolutional codes. This algorithm is critical to modern iteratively-decoded error-correcting codes incorporating codes and low-density parity-check codes. The BCJR algorithm is ideal as in it’s anything that increases the a posteriori probability of each bit and the Viterbi algorithm is optimal. In the presence of additive white Gaussian noise, the BCJR algorithm for decoding the output of a multiple-access channel known as the noisy three-user binary adder channel.