Algorithm for joint decoding of turbo codes and M-ary orthogonal modulation

In this paper, we consider the concatenation of turbo codes and M-ary orthogonal modulation. A modified decoding algorithm that utilizes the correlated nature of an orthogonal symbol drawn from a Hadamard matrix and the soft-input/soft-output module of turbo codes is introduced. This improved decoding algorithm can significantly lower the error shoulder and reduce the SNR required for a given error probability.