Vertaile menetelmiä

	Shannonin kanavakapasiteettiteoreema	LDPC-koodit (Low-Density Parity-Check Codes)
Tieteenala	Tietoliikennetekniikka	Tietoliikennetekniikka
Menetelmäperhe	Process / pipeline	Process / pipeline
Syntyvuosi	1948	1962
Kehittäjä	Claude Shannon	Robert Gallager
Tyyppi	fundamental theoretical bound	linear error-correcting code
Alkuperäislähde	Shannon, C. E. (1948). A mathematical theory of communication. Bell System Technical Journal, 27(3), 379-423.	Gallager, R. G. (1962). Low-density parity-check codes. IRE Transactions on Information Theory, 8(1), 21-28.
Rinnakkaisnimet	channel capacity, information theory bound	sparse codes, belief propagation codes
Liittyvät	5	5
Tiivistelmä	Shannon's channel capacity theorem, published in 1948, establishes the maximum rate at which information can be reliably transmitted over a noisy channel. Expressed as C = B log2(1 + S/N) for additive white Gaussian noise (AWGN), it is a fundamental bound in information theory and communications engineering. Shannon proved that reliable communication is possible at any rate below capacity, and impossible above it. This theorem underpins the design of all modern communication systems and motivates coding theory, modulation, and signal processing techniques.	LDPC codes, invented by Robert Gallager in 1962 and rediscovered in the 1990s by MacKay, are linear error-correcting codes defined by sparse parity-check matrices. They achieve performance within 0.4 dB of the Shannon limit with iterative belief-propagation decoding and have become the standard for modern wireless (WiFi-6, 5G NR, Digital Video Broadcasting). Unlike turbo codes, LDPC codes have a more elegant graph-theoretic structure and more mature theoretical analysis.