Patent
Methods and apparatus for reducing error floors in message passing decoders
Thomas Richardson
- 17 Dec 2004
121
TL;DR: In this paper, an iterative message passing decoder, operating in conjunction with a soft input-soft output signal processing unit (402), has an error floor performance region influenced by the decoder's suboptimal message passing nature.
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Abstract: An iterative message passing decoder, e.g., an LDPC decoder (404), operating in conjunction with a soft input - soft output signal processing unit (402), e.g., an ISI detector, has an error floor performance region influenced by the decoder’s suboptimal message passing nature. Error floor reduction is achieved by a simple message re-initialization mechanism. Decoder edge states, e.g., constraint to variable node messages in decoder memory, are reinitialized, e.g., for an iteration, during the decoding after soft values provided by signal-processing unit (402) have improved. During the message re-initialization and for some subsequent amount of iterative decoder processing, extrinsic information (416) fed back from the decoder to the signal processing unit (402) and/or soft values delivered to the decoder from the signal processing unit (402), in an outer communications loop, is temporarily frozen, e.g., using a switch and a buffer (410). Then, the outer communications loop is restored as the decoding continues, achieving improved decoding performance.
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Citations
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