Patent ID: 9621189
Date: 2017-04-11
CPC Classifications: H03M,H04L

Claim:
1. A method of identification and compensation for inversion of an input bit stream of LDPC (low density parity check) codes, the method comprising obtaining a code word of the LDPC code from a demodulator output and writing the LDPC code word into a buffer memory; and decoding the LDPC code word in an LDPC decoder, wherein the buffer memory, an inversion block, the LDPC decoder and a syndrome convergence analyzer are all connected in series, the buffer memory receiving the input bit stream, the LDPC decoder also outputting decoded information words at another output, and the syndrome convergence analyzer providing an output to the inversion block and to the LDPC decoder, and wherein the decoding includes: (i) calculating a syndrome for each iteration, (ii) in the syndrome convergence analyzer, analyzing a convergence of a weight of the syndrome, (iii) in the inversion block, generating an inversion feature for the input bit stream based on the analyzing, (iv) continuing the decoding if the inversion feature for the input bit stream shows no inversion, (v) if the inversion feature for the input bit stream shows evidence of inversion, resetting the LDPC decoder and analysis parameters for the convergence of the weight of the syndrome, (vi) reading a next code word from the buffer memory, and (vii) inverting the next code word, and feeding the next code word to the LDPC decoder for a next decoding operation.