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بررسی شبکه های سلولی موبایل







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







Wireless data standards
IEEE 802.11: wireless LAN/ad-hoc networking, 1, 2 or 11 Mbps, DSSS or FHSS with CSMA/CA RTS-CTS-ACK, 2.4 - 2.4835 GHz
Bluetooth: replacement for cables, short range (10 or 100 m), low power (1 or 100 mW), low cost, 1 Mbps max data rate, local piconets with master-slave operation
HomeRF: wireless home networking, 150 feet range, up to 10 devices, SWAP protocol
IEEE 802.15: wireless PAN, modes for low (< 10 kbps), medium (up to 200 kbps), and high (> 20 Mbps) data rates







Facts about wireless communication
Over 50% of US households have a cellular phone by 2003
Over 170M wireless data users(2003); projected to reach 1.3 billion by 2004
Over 200M mobile phone subscribers in Western Europe
Global revenue from wireless portals predicted to grow from $700M to $42 billion by 2005
Worldwide wireless subscribers to reach 1 billion by Q3 2002
WLAN revenues predicted at $785M by 2004
Forecasting a 59 percent growth rate for wireless usage in rural areas between 2000 and 2003







Underlying concepts
Electromagnetics
....