low density parity check (LDPC)

Low Density Parity Check (LDPC) are linear block codes for error correction. Linear block codes are those in which the sum of two code words results in a different code word.

Block codes were developed as early as the 1960s in connection with the iterative algorithms based on probabilities and are now being used again for error correction in transmission channels of cell phones and in digital television( DVB). LDPC codes are described by matrices for parity checking.

LDPC codes achieve and partially exceed the performance of turbo codes, especially for long block lengths. Thus, for block lengths of more than 10,000 characters, signal-to- noise ratios are achieved which lie in the range of 0.1 dB of the data transmission ratedetermined according to the Shannon theorem.

LDPC is used in satellite-based and terrestrial transmission of digital TV, DVB-S2 and DVB-T2, among other applications. It can also optionally be used in WLANs according to 802.11.