Wireless Network Introduction

Transcription

1 Wireless Network Introduction Module W.bas.1 Shanghai Jiaotong University Shanghai, China University of New Mexico Albuquerque, NM, USA 1

2 Wireless network introduction W.bas.1-2 Wireless age Broadband wireless Technology limitation & motivation Wireless new technology & development Cellular telephony Cordless telephony Wireless LANs & PANs Wireless networks Devices Challenges Trends End of module W.bas.1

3 Wireless age W.bas.1-3 Guglielmo Marconi invented the wireless telegraph in 1896 Communication by encoding alphanumeric characters in analog signal Sent telegraphic signals across the Atlantic Ocean Communications satellites launched in 1960s Advances in wireless technology Radio, television, mobile telephone, communication satellites More recently Satellite communications, wireless networking, cellular technology

4 Broadband wireless technology W.bas.1-4 Higher data rates obtainable with broadband wireless technology Graphics, video, audio Shares same advantages of all wireless services: convenience and reduced cost Service can be deployed faster than fixed service No cost of cable plant Service is mobile, deployed almost anywhere

5 Wireless technologies limitation W.bas.1-5 Wireless is convenient and less expensive Limitations and political and technical difficulties inhibit wireless technologies Lack of an industry-wide standard Device limitations E.g., small LCD on a mobile telephone can only displaying a few lines of text E.g., browsers of most mobile wireless devices use wireless markup language (WML) instead of HTML

6 Motivation for wireless networks W.bas.1-6 Deployment: zero cost for wiring or rewiring Communications can reach where wiring is infeasible or costly rural areas, historical buildings, battlefield, vehicles Auto instantaneous communications without physical connection setup Bluetooth??? Communication satellites, global coverage

7 Motivation for wireless networks W.bas.1-7 Operation: roaming/mobility allows flexibility to stay connected anywhere and any time Daily life/work need for mobility and uninterrupted access Consumers are used to the flexibility instantaneous, uninterrupted, fast access regardless of the application. It s a small world, globalization Increasing dependence on communication (wireless) services for business and personal reasons

8 Wireless network introduction W.bas.1-8 Wireless age Broadband wireless Technology limitation & motivation Wireless new technology & development Cellular telephony Cordless telephony Wireless LANs & PANs Wireless networks Devices Challenges Trends End of module W.bas.1

9 New Technology W.bas.1-9 UMTS, WLAN, DAB, GSM, cdma2000, TETRA,... ad hoc Personal Travel Assistant, DAB, PDA, laptop, GSM, UMTS, WLAN, Bluetooth,...

10 New technology W.bas.1-10 What new technology brings to us? Wireless LANs Wireless WANs WiMax UWB Wireless over optical Wireless development Wireless communications overall Cellular telephony Cordless telephony Wireless LANs & PANs

11 Wireless communications W.bas.1-11 Cellular telephony Started early 1980s 1G: analog signal, frequency modulation 2G: digital transmission, GSM, TDMA, CDMA. 2.5G: includes data, GPRS General Packet Radio Service 3G: multimedia up to 2Mbps, global roaming, W-CDMA, UMTS 4G: by 2010, further enhancement, universal access Wireless LANs Started late 1990s Satellite-based communication

12 Wireless communications W.bas.1-12 Timelines for wireless systems 1981: NMT : NMT 900 cellular phones 1992: GSM analogue digital 1994: DCS : CDMA 2000: GPRS 1983: AMPS 1991: D-AMPS 1993: PDC 2001: IMT : Inmarsat-A 1988: Inmarsat-C satellites 1992: Inmarsat-B Inmarsat-M 1998: Iridium 200?: Fourth Generation (Internet based) cordless phones 1980: CT0 1984: CT1 1987: CT : CT 2 wireless LAN 1991: DECT 199x: proprietary 1997: IEEE : b, Bluetooth 2000: IEEE a

13 W.bas.1-13 Cellular telephony in Europe GSM (Global System for Mobilecomm) 1982, Specification only, pan-europe, 900MHz 1992, fully digital, 900MHz, 124 channels, roaming Services: data with 9.6kbit/s, FAX, voice <160 char short message services 1994, 1800MHz as a new frequency band Also called GSM-1800 or DCS-1800 (Digital Cellular System) 2000, GPRS, up to 50 kbit/s (packet oriented!) Europe believes in Standards Motorola GSM cellphone GSM base station in Poland

14 W.bas.1-14 Cellular telephony in USA AMPS (Advanced Mobile Phone System) TDMA CDMA 1983, Analog, USA, 850MHz 1996, digital, 850MHz 1900MHz 1993, digital, 850MHz 1900MHz GSM-1900, move to USA 1900MHz Also called PCS-1900 Nokia TDMA cellphone CDMA antenna USA believes in market forces

15 Telephones at home went wireless W.bas.1-15 CT (Cordless Telephones) 1980: CT : CT-1 Europe 1987: CT-2, British Standard 1994, CT-2 extension, Europe, 864MHz, 32kbits/s DECT (Digital Enhanced Cordless Telecomm) 1998, MHz, A range of m, 10K users/km duplex channels 1.2 Mbits/s for data, with voice encryption, authentication Uniden cordless phone

16 W.bas.1-16 Wireless LANs & PANs WLANs European HIPERLAN (High Performance Radio LAN) 1996, 5.2GHz, 23.5Mbits/s IEEE WPANs 1997, 2.4 GHz ISM (Industrial, Science, Medical) band, 2 Mbits/s 1999, b, Wi-Fi, 11 Mbits/s a, g, 802.n Bluetooth, IEEE , 2.4 GHz, 1 Mbits/s Linksys wireless router

17 Wireless network introduction W.bas.1-17 Wireless age Broadband wireless Technology limitation & motivation Wireless new technology & development Cellular telephony Cordless telephony Wireless LANs & PANs Wireless networks Devices Challenges Trends End of module W.bas.1

18 Wireless terminal devices W.bas.1-18 Mobile phones voice, data simple graphical displays GSM Laptop fully functional standard applications battery; Sensors, embedded controllers PDA data simpler graphical displays Performance/Weight/Power Consumption

19 W.bas.1-19 Wireless compared to wired networks Higher loss-rates due to interference Restrictive regulations of frequencies lmited frequencies have to be coordinated Low transmission rates Higher delays, higher jitter connection setup time with GSM in the second range, several hundred milliseconds for other wireless systems Lower security, simpler active attacking radio interface accessible for everyone Always shared medium secure access mechanisms important

20 Wireless network challenges W.bas.1-20 Network support for mobility location identification, handover,... Efficient use of finite radio spectrum cellular frequency reuse, medium access control protocols,... Integrated services: voice, data, multimedia overall service differentiation, priorities, resource sharing,... Maintaining QoS over unreliable links Much harder than maintaining Reliable service Connectivity and coverage Internetworking issues Security privacy, authentication,...

21 Worldwide wireless subscribers W.bas Americas Europe Japan others total Prediction made in

22 Worldwide wireless subscriber W.bas Subscribers [million] : 1.5 billion users

23 Worldwide wireless subscriber W.bas year prediction in 2003

24 Wireless network introduction W.bas.1-24 Wireless age Broadband wireless Technology limitation & motivation Wireless new technology & development Cellular telephony Cordless telephony Wireless LANs & PANs Wireless networks Devices Challenges Trends End of module W.bas.1