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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
7 i3 ], M# F7 |0 j2 }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: 7 ]9 Z. A: _6 a$ P- z1 z6 x( y
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。 # G) U: b+ v# I2 g
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。
; T+ ^1 U& s1 l* Y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。; e0 g R1 _1 U: p- p! Y( ~/ f
無線區域網路與無縫隙通信(Wi-Fi/MiMax/LTE)。$ n/ R) {. x& l- k- h- e
19th Century3 l& p4 d. @+ T
1846- earliest talk on EM wave, “Thoughts on ray vibrations,” Michael Faraday (1791-1867). c; U; `( i0 ^% f" U
1864 - “ Maxwell’s equations,” James Clark Maxwell (1831-1879)
) r/ S1 I1 H# ]1887 - first microwave-like experiment, “electric spark at l~ 10 cm induces at a distance wire loop,” Heinrich Rudolf Hertz (1857-1894)
& G/ L/ b% a Y* _1895- wireless telegraphic communication2 z* C% L' N, u( `$ J \
1900- trans-Atlantic Ocean telegraph, Guglielmo Marconi (1874-1937)
* c- T4 K8 P& E, b0 E, W20th Century5 K2 ]5 z( L- H& Q. m( }
1921- magnetron, A.W.Hull* r5 J2 e7 U* ?, c D& Q. m: U
1930- wave propagation in waveguide, George C. Southworth q4 Q( n5 n/ \6 E2 ?: T
1937- Klystron, Russell Varian, Siguard Varian and William Hansen* O6 g" S7 x7 L) [ ]! [1 o
World War II – radar, MIT Radiation Laboratory7 n& P. K/ a" D ~5 i( Z
~1950- coaxial cables for radio communication
9 L2 c% K3 [0 K& g~1960- satellite communication
" E7 z9 @7 e5 X3 ?! H~1980- remote sensing satellite, DBS (direct broadcast satellite)* S- X5 N' h" ?7 o! O
~1990- PCN/PCS (personal communications network/person communication services), GPS (global positioning system), VSAT (very small aperture terminals)* P$ ]: O" m. f
~2000- Digital DBS, WLL (wireless local loop), GII (global information initiative) using mobile satellite network, fibers, cables and wireless.
4 P0 n' U5 Z6 C3 o+ i 21st Century – RF-SOC use standard mature Si-base technologies to design RFIC. |
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