Lowering LDPC Error Floors by Postprocessing
A class of combinatorial structures, called absorbing sets, strongly influences the performance of Low-Density Parity Check (LDPC) decoders at low error rates. Past experiments have shown that a class of absorbing sets determines the error floor performance of the (2048,1723) Reed-Solomon based LDPC code (RS-LDPC). A post-processing approach is formulated to exploit the structure of the absorbing set by biasing the reliabilities of selected messages in a message-passing decoder. The approach converges quickly and can be efficiently implemented with minimal overhead.