LDPC Decoder - Hard Decision

Dear all,

the comm.LDPCDecoder provides a LDPC decoder which has the Property Decision Method. According to the documentiation, when this is set to 'hard decision', the output are hard bits, not LLRs. My question is (and I could not find this in the doc): Is the algorithm used to decode the LDPC code still the same as in soft decision (i.e., does the decoding iteration still work with LLRs) or is it indeed a hard decision algorithm (i.e. the bit flipping algorithm)?

Thanks for your help

Answer 1

[Marco]

Hi Christoph, generally, in Hard decision decoding, the received codeword is compared with the all possible codewords and the codeword which gives the minimum Hamming distance is selected. Instead, in Soft decision decoding, the received codeword is compared with the all possible codewords and the codeword which gives the minimum Euclidean distance is selected. Thus the soft decision decoding improves the decision making process by supplying additional reliability information (calculated Log-Likelihood Ratio). comm.LDPCDecoder works in this way.

BR /Marco