Low density parity check codes

Abstract

Low density parity check (LDPC) codes are forward error-correction codes, invented by Robert Gallager in his MIT Ph.D. dissertation, 1960. The LDPC codes are ignored for long time due to their high computational complexity and domination of highly structured algebraic block and convolutional codes for forward error correction. A number of researchers produced new irregular LDPC codes which are known as new generalizations of Gallager’s LDPC codes that outperform the best turbo codes with certain practical advantages. LDPC codes have already been adopted in satellite-based digital video broadcasting and long-haul optical communication standards. This chapter discusses LDPC Code Properties, construction of parity check matrix for regular and irregular LDPC codes, efficient Encoding and Decoding of LDPC Codes, performance analysis of LDPC Codes.