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發表於 2008-11-18 01:21:37
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未來通信主導技術6 a; V/ w& n/ _
個人通信服務環境中,除了全球性個人通信(UPT)為智慧型網路技術外,其餘皆是無線技術。無線技術可分三類: 0 Z% O7 W: L' s) _
高密度、低功率無線系統:在此所謂低功率是指六百毫瓦或更低,而細胞是指劃分成許多相互銜接之小服務區。一般而言,細胞半徑的大小是依通信量的多寡而定,大細胞涵蓋範圍約二至二十公里,小細胞在一公里以內,而微細胞則在一百公尺左右。
1 Z& b3 _- X0 M3 |. _' S# I高速度、廣涵蓋區域之細胞式行動電話系統:即為AMPSGSM和3G系統。
1 g2 g: d. A, {% \5 S) A# x高密度、廣涵蓋區域之微細胞式系統:是採用如CT2、DECT、PHS或WACS等技術,從現有之固定電話用戶側著手。: C* s9 J. Y! x' X+ s2 C9 q. d [
無線區域網路與無縫隙通信(Wi-Fi/MiMax/LTE)。( z) K: z7 y& D8 z6 J' i' c) P7 h
19th Century3 @) J2 F. n% v/ \' F% B! K* }5 O
1846- earliest talk on EM wave, “Thoughts on ray vibrations,” Michael Faraday (1791-1867)/ P9 x- V7 G: Z9 ]) m: M
1864 - “ Maxwell’s equations,” James Clark Maxwell (1831-1879)
4 Q$ \4 [" M/ G- f2 ]1 m# r1887 - first microwave-like experiment, “electric spark at l~ 10 cm induces at a distance wire loop,” Heinrich Rudolf Hertz (1857-1894) D0 G8 F% {2 `" H* _: g& L
1895- wireless telegraphic communication5 _/ W1 p1 F2 x) c# r
1900- trans-Atlantic Ocean telegraph, Guglielmo Marconi (1874-1937)
8 j( J4 |2 X4 p9 d2 ^/ X7 q20th Century# { z) X$ @" P
1921- magnetron, A.W.Hull
* j9 f1 B+ a" ^- X9 X1930- wave propagation in waveguide, George C. Southworth
# j4 M. Q$ L# r' I: _1937- Klystron, Russell Varian, Siguard Varian and William Hansen
7 U, `) d+ ^" r s/ p, S5 hWorld War II – radar, MIT Radiation Laboratory
2 L# Z4 z: H# }, S% u& V n2 V+ q) Q~1950- coaxial cables for radio communication) s$ }4 g* J& E
~1960- satellite communication
3 p9 a; X' Q1 W+ G+ d- f7 v/ {~1980- remote sensing satellite, DBS (direct broadcast satellite)# w; D4 E8 L- b$ X, r
~1990- PCN/PCS (personal communications network/person communication services), GPS (global positioning system), VSAT (very small aperture terminals)
% J; X+ s i, u# b~2000- Digital DBS, WLL (wireless local loop), GII (global information initiative) using mobile satellite network, fibers, cables and wireless.
; Y# t' n1 Q V7 d 21st Century – RF-SOC use standard mature Si-base technologies to design RFIC. |
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