On Soft Decoding of Some Binary RLL-Transmission Codes in Systems with Coherent BPSK Modulation

Recently some RLL-LDPC and RLL-Turbocodes were proposed. In BSC the hard decoding methods applied for the original codes - not possessing the RLL properties could be used for these codes without any changes. The questions arise if also the standard soft decoding methods could be used for their decoding in Additive White Gaussian Noise channel without changes. In this paper it is shown that the answer is positive if coherent BPSK modulation is used and the received signal is filtered by Matched Filter. It is shown that the only necessary operation is the inversion of the log-likelihood ratio forming the input to the decoder from the channel for values corresponding to the inverted bits by modifier in transmitter.