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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, u s! t/ n& g! D! \& ^
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:
3 [* A; c- E" I) O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。
; M1 ~& b: Q4 F" }0 z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。 ' B) [7 Q% w1 l5 U" R
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。8 U3 ]! W5 C7 ~, |" S3 R! q
無線區域網路與無縫隙通信(Wi-Fi/MiMax/LTE)。
3 i! j1 _( s6 V( R. b* [8 L19th Century3 d( A; a3 h% O
1846- earliest talk on EM wave, “Thoughts on ray vibrations,” Michael Faraday (1791-1867)+ i5 I. I# ~+ [7 C& ^
1864 - “ Maxwell’s equations,” James Clark Maxwell (1831-1879)
3 o0 }: K8 z+ Y3 b5 [. x+ l3 y1887 - first microwave-like experiment, “electric spark at l~ 10 cm induces at a distance wire loop,” Heinrich Rudolf Hertz (1857-1894)
9 N3 c' z* b7 s1895- wireless telegraphic communication
. s3 z7 U. F/ i$ t4 e1900- trans-Atlantic Ocean telegraph, Guglielmo Marconi (1874-1937)9 T. n; Y4 b) A5 ]
20th Century
3 W# G- S' }# Y3 d p5 K* X1921- magnetron, A.W.Hull: V- E G& A+ a- f _0 m
1930- wave propagation in waveguide, George C. Southworth
: J* l0 `0 F, P, `* T1937- Klystron, Russell Varian, Siguard Varian and William Hansen; f* R: C1 a6 ?% H
World War II – radar, MIT Radiation Laboratory
) ]- e+ w! K( }4 T6 n~1950- coaxial cables for radio communication2 z" L& o) [5 S9 t. x
~1960- satellite communication( K1 N: d7 j7 J8 J+ s
~1980- remote sensing satellite, DBS (direct broadcast satellite)6 N8 D; X4 n! O* P4 e# r
~1990- PCN/PCS (personal communications network/person communication services), GPS (global positioning system), VSAT (very small aperture terminals)* ]4 x. k7 G: _( x! o; e ~
~2000- Digital DBS, WLL (wireless local loop), GII (global information initiative) using mobile satellite network, fibers, cables and wireless.
# b+ O" f5 ]% `# ^! i 21st Century – RF-SOC use standard mature Si-base technologies to design RFIC. |
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