Introduction - If you have any usage issues, please Google them yourself
Low-density parity-check (LDPC) codes are forward error-correction codes,
first proposed in the 1962 PhD thesis of Gallager at MIT. At the time, their
incredible potential remained undiscovered due to the computational demands
of simulation in an era when vacumm tubes were only just being replaced by
the first transistors. They remained largely neglected for over 35 years. In the
mean time the field of forward error correction was dominated by highly structured
algebraic block and convolutional codes. Despite the enormous practical
success of these codes, their performance fell well short of the theoretically
achievable limits set down by Shannon in his seminal 1948 paper. By the late
1980s, despite decades of attempts, researchers were largely resigned to this
seemingly insurmountable theory–practice gap.