سایت پاورپوینت دانشجویی آماده درسی با طبقه بندی ,نمونه پاورپوینت

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حجم : 2119 کیلوبایت

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History of wireless communication
1897: Marconi demonstrated transmission of radio waves to a ship at sea 29 km away
1915: Wireless telephony established-- Virginia and Paris
1920s: Radio broadcasting became popular
1930s: TV broadcasting began
1946: First public mobile telephone service in US
1960s: Bell Labs developed cellular concept-- brought mobile telephony to masses
1960’s: Communications satellites launched
Late 1970s: IC technology advances enable affordable cellular telephony-- ushers in modern cellular era







Modern cellular standards
1979: NTT (Japan), FDMA, FM, 25 kHz channels, 870-940 MHz
1983: AMPS (US), FDMA, FM, 30 kHz channels, 824-894 MHz
1985: TACS (Europe), FDMA, FM, 25 kHz channels, 900 MHz
1990: GSM (EuropeTDMA, GMSK, 200 kHz channels, 890-960 MHz
1991: USDC/IS-54 (), US), TDMA, p/4 DQPSK, 30 kHz channels, 824-894 MHz
1993: IS-95 (US), CDMA, BPSK/QPSK, 1.25 MHz channels, 824-894 MHz and 1.8-2.0 GHz
1993: CDPD (US), ) Cellular Digital Packet Data(: FHSS, GMSK, 30 kHz channels, 824-894 Mhz
2001: UMTS/IMT-2000 (3rd generation European cellular standard), supports data and voice (up to 2 Mbps), 1885-2025 MHz and 2110-2200 Mhz

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