Chebyshev inequality based max* approximation for reduced complexity decoding of turbo TCM

A reduced-complexity modified decoding algorithm for turbo trellis-coded modulation (TTCM) is proposed and evaluated in terms of complexity and bit error rate (BER) performance in an additive white Gaussian noise (AWGN) channel. A novel method is derived from the Chebyshev inequality. In this approach, the max* operation is performed on n≥2 arguments, thus the recursive calculations are avoided and a significant reduction in the number of operations performed per decoding step, as compared with the conventional Log-MAP, is achieved. Computer simulated BER performance evaluation results and complexity comparison are reported showing the near-optimal performance as well as noticeable implementation advantages of the proposed algorithms with respect to the Log-MAP decoding.