Σύγκριση μεθόδων

	Θεώρημα Χωρητικότητας Καναλιού του Shannon	Κώδικες Ελέγχου Χαμηλής Πυκνότητας (LDPC)	Πολλαπλών Εισόδων Πολλαπλών Εξόδων (MIMO)	Ορθογώνια Διαίρεση Συχνότητας (OFDM)
Πεδίο	Τηλεπικοινωνίες	Τηλεπικοινωνίες	Τηλεπικοινωνίες	Τηλεπικοινωνίες
Οικογένεια	Process / pipeline	Process / pipeline	Process / pipeline	Process / pipeline
Έτος προέλευσης	1948	1962	1995	1971
Δημιουργός	Claude Shannon	Robert Gallager	Telatar, Foschini, and Gans	Weinstein and Ebert
Τύπος	fundamental theoretical bound	linear error-correcting code	spatial multiplexing technique	multicarrier modulation scheme
Θεμελιώδης πηγή	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.	Telatar, I. (1999). Capacity of multi-antenna Gaussian channels. European Transactions on Telecommunications, 10(6), 585-595.	Weinstein, S. B., & Ebert, P. M. (1971). Data transmission by frequency-division multiplexing using the discrete Fourier transform. IEEE Transactions on Communication Technology, 19(5), 628-634.
Εναλλακτικές ονομασίες	channel capacity, information theory bound	sparse codes, belief propagation codes	spatial multiplexing, antenna diversity	multicarrier modulation
Συναφείς	5	5	5	5
Σύνοψη	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.	MIMO is a technique that uses multiple transmit and receive antennas to significantly increase channel capacity and reliability. Pioneered theoretically by Telatar (1999) and Foschini & Gans (1998), MIMO exploits multipath propagation—typically a liability in wireless—as an asset by creating independent spatial channels. It is now fundamental to all modern wireless systems including LTE, WiFi-6, and 5G, where it provides both capacity gains through spatial multiplexing and robustness through diversity.	OFDM is a multicarrier modulation technique that divides a wideband channel into many narrowband orthogonal subcarriers. Introduced by Weinstein and Ebert in 1971, it exploits the duality between time and frequency domains to efficiently use spectrum while mitigating intersymbol interference in frequency-selective channels. OFDM is now the standard for high-speed wireless systems including WiFi, cellular LTE, and digital broadcasting.