A new type of ultimate-Shannon-limit channel codes

Abstract

In most existing digital communication systems, the received signal strength is usually larger than the noise level. Alternatively, the bit-energy-to-noise-power-spectral-density (Eb/N0) is assumed to be greater than 0 dB. However, in some specific applications such as deepspace communications and quantum key distribution, the received signal power is smaller than the noise power. Under such circumstances, strong error correction codes are required to provide a reliable link between the transmitter and the receiver. In this talk, a new type of error-correction code called “protograph-based low-density parity-check Hadamard codes” is introduced. The codes are shown to provide excellent error performance not only when Eb/N0 is smaller than 0 dB, but also when Eb/N0 approaches the ultimate Shannon limit -1.59 dB.