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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. u4 U* p3 A5 i. ]* o% C
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:
2 g5 R4 t! k; X! h" |7 U/ H) ?. d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。 & m2 d8 n( C$ p6 D5 f( n) }8 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。
- J- R- |& N$ ]) [; b' s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。; g, w i# ~8 n% n
無線區域網路與無縫隙通信(Wi-Fi/MiMax/LTE)。- {' ? K5 V# }* d# a/ {- z* a
19th Century
( x/ l V' L' Q! V+ l' a0 n K1846- earliest talk on EM wave, “Thoughts on ray vibrations,” Michael Faraday (1791-1867)) `3 p% d9 {7 Y5 |& a# z# B) k( ^ q
1864 - “ Maxwell’s equations,” James Clark Maxwell (1831-1879)7 c8 q7 J2 g5 @5 u: Q! e: W
1887 - first microwave-like experiment, “electric spark at l~ 10 cm induces at a distance wire loop,” Heinrich Rudolf Hertz (1857-1894)
, O! ?. f+ T0 o+ k5 L' f1895- wireless telegraphic communication
! J5 P$ H9 \3 }+ v N" H1900- trans-Atlantic Ocean telegraph, Guglielmo Marconi (1874-1937)
4 `8 r4 }0 v- `: l3 f0 i4 I20th Century- }6 e) E* P* ^
1921- magnetron, A.W.Hull/ ^8 H3 Z# ^' v6 R k
1930- wave propagation in waveguide, George C. Southworth
6 P! H+ Z& N2 R- e* l ~1 V1937- Klystron, Russell Varian, Siguard Varian and William Hansen
' i8 ?. N& G5 @5 HWorld War II – radar, MIT Radiation Laboratory2 C/ Y! j: J2 h. q: |/ \
~1950- coaxial cables for radio communication
' X1 ?3 }) X! M& L4 L+ C~1960- satellite communication: ^0 |1 g* P @0 u
~1980- remote sensing satellite, DBS (direct broadcast satellite)8 v; `3 x; A1 S" A1 E3 M* `! i& |
~1990- PCN/PCS (personal communications network/person communication services), GPS (global positioning system), VSAT (very small aperture terminals)% \& Q; ^8 [) G# b
~2000- Digital DBS, WLL (wireless local loop), GII (global information initiative) using mobile satellite network, fibers, cables and wireless.6 h" ~# Q+ e* A2 I: {( ~' g7 W
21st Century – RF-SOC use standard mature Si-base technologies to design RFIC. |
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