Σύγκριση μεθόδων

	Μοντέλο Πρόβλεψης Απωλειών Διαδρομής Okumura-Hata	Πολλαπλών Εισόδων Πολλαπλών Εξόδων (MIMO)	Ορθογώνια Διαίρεση Συχνότητας (OFDM)	Θεώρημα Χωρητικότητας Καναλιού του Shannon
Πεδίο	Τηλεπικοινωνίες	Τηλεπικοινωνίες	Τηλεπικοινωνίες	Τηλεπικοινωνίες
Οικογένεια	Process / pipeline	Process / pipeline	Process / pipeline	Process / pipeline
Έτος προέλευσης	1968	1995	1971	1948
Δημιουργός	Masahiro Okumura and Masahiro Hata	Telatar, Foschini, and Gans	Weinstein and Ebert	Claude Shannon
Τύπος	empirical path loss model	spatial multiplexing technique	multicarrier modulation scheme	fundamental theoretical bound
Θεμελιώδης πηγή	Okumura, Y., Ohmori, E., Kawano, T., & Fukuda, K. (1968). Field strength and its variability in VHF and UHF land mobile radio service. Review of the Electrical Communication Laboratory, 16(9-10), 825-873.	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.	Shannon, C. E. (1948). A mathematical theory of communication. Bell System Technical Journal, 27(3), 379-423.
Εναλλακτικές ονομασίες	path loss model, propagation prediction	spatial multiplexing, antenna diversity	multicarrier modulation	channel capacity, information theory bound
Συναφείς	4	5	5	5
Σύνοψη	The Okumura-Hata model is an empirical propagation model for predicting path loss in mobile radio systems. Developed by Okumura (1968) and mathematically formalized by Hata (1980), it is one of the most widely used models for cellular network planning. The model predicts median path loss as a function of frequency, distance, and antenna heights, with environment-specific correction factors. Despite its age, the Okumura-Hata model remains a standard in 2G/3G planning and is often used as a baseline for more sophisticated models.	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.	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.