Iterative Soft Input Soft Output Decoding of Reed-Solomon Codes by Adapting the Parity Check Matrix

摘要

An iterative algorithm is presented for soft-input-soft-output (SISO)decoding of Reed-Solomon (RS) codes. The proposed iterative algorithm uses thesum product algorithm (SPA) in conjunction with a binary parity check matrix ofthe RS code. The novelty is in reducing a submatrix of the binary parity checkmatrix that corresponds to less reliable bits to a sparse nature before the SPAis applied at each iteration. The proposed algorithm can be geometricallyinterpreted as a two-stage gradient descent with an adaptive potentialfunction. This adaptive procedure is crucial to the convergence behavior of thegradient descent algorithm and, therefore, significantly improves theperformance. Simulation results show that the proposed decoding algorithm andits variations provide significant gain over hard decision decoding (HDD) andcompare favorably with other popular soft decision decoding methods.