A low-complexity decoding algorithm for RA code with Chebyshev Polynomial Fitting

RA (Repeat Accumulate) code has been widely used in wireless communication systems. But the BP (Belief Propagation) decoding algorithm which is commonly used in RA Code has high complexity. In order to reduce the complexity of BP algorithm while maintaining coding performance, we proposed Chebyshev-Polynomial-Fitting based BP (CPF-BP) decoding algorithm. In CPF-BP decoding algorithm, we used polynomial which is generated by chebyshev fitting algorithm instead of hyperbolic tangent operation in BP decoding algorithm to reduce the implementation complexity. Experiment and simulation results show that this low-complexity algorithm removes hyperbolic tangent operation in conventional BP algorithm with same amount of multiplier under the parameters setting in the paper. The performance degradation of CPF-BP algorithm is negligible which is less than 0.6dB at BER of 10^-4 compared with conventional BP algorithm.