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未來通信主導技術: S, O5 O9 J8 L7 S8 g
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: * Q, F' N* y0 @3 x3 ^+ n% `3 w
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。 : |" F; V( T3 j$ c/ g" X' H
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。 * Y7 a& U- r( E2 @6 {
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。
$ v. a8 V# {: L無線區域網路與無縫隙通信(Wi-Fi/MiMax/LTE)。
$ u9 g5 l, G! m k/ w) [3 L/ z19th Century
% P1 ^/ p) ]" T* I1846- earliest talk on EM wave, “Thoughts on ray vibrations,” Michael Faraday (1791-1867)
2 l* S2 D* v: W3 m1864 - “ Maxwell’s equations,” James Clark Maxwell (1831-1879)- w* T R; d' |" w! o1 l
1887 - first microwave-like experiment, “electric spark at l~ 10 cm induces at a distance wire loop,” Heinrich Rudolf Hertz (1857-1894)
( {6 ]6 q' h) V0 e1 Y' T1895- wireless telegraphic communication
5 y l2 @- b* w; ^! E( a# E R2 K1900- trans-Atlantic Ocean telegraph, Guglielmo Marconi (1874-1937) N4 }; |) u% |9 m9 C6 o% p2 Q
20th Century
1 z3 V! S& y8 A8 Q6 P1921- magnetron, A.W.Hull# V( ~! `/ D( Z5 V H" S" o
1930- wave propagation in waveguide, George C. Southworth
) k$ R" P7 _; F: S+ `$ _1937- Klystron, Russell Varian, Siguard Varian and William Hansen) `5 o- `0 P. l2 Q6 e
World War II – radar, MIT Radiation Laboratory9 ^3 }7 h# ^. F: ?5 e2 `
~1950- coaxial cables for radio communication
- A* S+ o) { b- {~1960- satellite communication' B3 G/ R/ {2 L/ d0 W* o6 e1 G
~1980- remote sensing satellite, DBS (direct broadcast satellite)- F4 H4 r% `1 `7 ^% ~
~1990- PCN/PCS (personal communications network/person communication services), GPS (global positioning system), VSAT (very small aperture terminals); x: _. j; K3 b
~2000- Digital DBS, WLL (wireless local loop), GII (global information initiative) using mobile satellite network, fibers, cables and wireless.* V, z$ [7 A! I- w
21st Century – RF-SOC use standard mature Si-base technologies to design RFIC. |
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