19-09-2017, 04:04 PM
In information theory a low density parity check code (LDPC) is a linear error correction code, a method for transmitting a message over a noisy transmission channel. An LDPC is constructed using a small bipartite graph. LDPC codes are codes that approximate capacity, which means that there are practical constructs that allow the noise threshold to be set very close (or even arbitrarily near the binary erase channel) to the theoretical maximum (the Shannon boundary ) for a channel without symmetrical memory. The noise threshold defines an upper limit for channel noise, to which the probability of loss of information can be made as small as desired. Using iterative belief propagation techniques, LDPC codes can be decoded in linear time to their block length.
LDPC codes are finding increasing use in applications that require reliable and highly efficient information transfer over bandwidth links or channel return links in the presence of corrupting noise. The implementation of LDPC codes has lagged behind other codes, especially turbo-codes. The key patent for the Turbo Codes expired on August 29, 2013. LDPC codes are also known as Gallager codes, in honour of Robert G. Gallager, who developed the LDPC concept in his doctoral thesis at the Massachusetts Institute of Technology in 1960 .
LDPC codes are finding increasing use in applications that require reliable and highly efficient information transfer over bandwidth links or channel return links in the presence of corrupting noise. The implementation of LDPC codes has lagged behind other codes, especially turbo-codes. The key patent for the Turbo Codes expired on August 29, 2013. LDPC codes are also known as Gallager codes, in honour of Robert G. Gallager, who developed the LDPC concept in his doctoral thesis at the Massachusetts Institute of Technology in 1960 .