Generalized Belief Propagation Based Deliberate Bit Flipping Modulation Coding
Mohsen Bahrami, Bane V. Vasic · 2016
We propose a novel approach to modulation coding using the Generalized Belief Propagation (GBP) algorithm. The idea is to completely eliminate a constrained encoder and, instead, embed a constraint into an error correction codeword by deliberately flipping the bits that violate the constraint. The GBP algorithm is used to keep the number of flipped bits small in order not to overburden the decoder. We incorporate our method to impose the two-dimensional (2D) no isolated bit constraint on a low-density parity check (LDPC) coded 2D data array. Furthermore, we show that the number of flipped bits can be optimized so that it is not beyond the error correcting capability of the code. Applied to Two Dimensional Magnetic Recording (TDMR) systems, our approach results in an order of magnitude gain in the frame error rate.