Abstract. The theme of this paper
is investigation of the characteristics of error-correcting low-density
parity-check codes (LDPC) which enable communication at relatively low received
signal/noise and provide very high power efficiency. Specific feature of
investigated codes is construction of these by means of full LDPC code word and
information volume shortening. According to this the broad class of LDPC codes
is constructed with variety of code-rates and information volumes. The full
(original) LDPC codes are based on the finite geometries (finite Eucledean and
projective geometries). The decoding algorithms for that are symbol-by-symbol
decoding developed for common class LDPC codes, namely, BP (belief propagation)
and BP modification (mBP) decoding algorithms. The BP and mBP decoding
algorithms are iterative and for implementation the signal/noise is not
required. The resulted characteristics of full and shortened low-density
parity-check codes (namely, duration of code words, information volume, code
rate, error performances) are presented. The original LDPC codes are cyclic and
have encoding and decoding algorithms with low complexity implementation. The
computer simulations for encoding and iterative decoding algorithms for the
number of turbo-codes with different code rate and information volumes are
performed. The results of computer simulations have shown that mBP decoding
algorithm is more effective than BP decoding algorithm (difference between
signal/noise is more 0.2 dB). The results of encoding and decoding algorithm realization
using FPGA VIRTEX-5SX
are presented, in particularly, the information rate 200 Mb/s is achieved for
generator clock 180 MHz and for 10 iterations.
Key words: noise-immunity, low-density parity-check
codes,
iterative decoding.
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