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Introduction to Mobile Communications

Introduction to Mobile Communications

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Introduction to Mobile Communications

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  1. Introduction to Mobile Communications TCOM 552, Lecture #1 Hung Nguyen, Ph.D. 28 August, 2006

  2. Chapter 10: Cellular Wireless Networks • Cellular wireless network design issues • First generation analog (traditional mobile telephony service) • Second generation digital cellular networks • Time-division multiple access (TDMA) • Code-division multiple access (CDMA) • Third generation networks Hung Nguyen, TCOM 552, Fall 2006

  3. Chapter 2: Transmission Fundamentals • Basic overview of transmission topics • Data communications concepts • Includes techniques of analog and digital data transmission • Channel capacity • Transmission media • Multiplexing Hung Nguyen, TCOM 552, Fall 2006

  4. Chapter 6: Signal Encoding Techniques • Wireless transmission • Analog and digital data • Analog and digital signals Hung Nguyen, TCOM 552, Fall 2006

  5. Chapter 5: Antennas and Propagation • Principles of radio and microwave • Antenna performance • Wireless transmission modes • Fading Hung Nguyen, TCOM 552, Fall 2006

  6. Chapter 8: Coding and Error Control • Forward error correction (FEC) • Using redundancy for error detection • Automatic repeat request (ARQ) techniques Hung Nguyen, TCOM 552, Fall 2006

  7. Chapter 7: Spread Spectrum • Frequency hopping • Direct sequence spread spectrum • Code division multiple access (CDMA) Hung Nguyen, TCOM 552, Fall 2006

  8. Chapter 10: Cellular Wireless Networks • Cellular wireless network design issues • First generation analog (traditional mobile telephony service) • Second generation digital cellular networks • Time-division multiple access (TDMA) • Code-division multiple access (CDMA) • Third generation networks Hung Nguyen, TCOM 552, Fall 2006

  9. Chapter 13: Wireless LAN Technology • Overview of LANs and wireless LAN technology and applications • Transmission techniques of wireless LANs • Spread spectrum • Narrowband microwave • Infrared Hung Nguyen, TCOM 552, Fall 2006

  10. Chapter 12: Mobile IP and Wireless Access Protocol • Modifications to IP protocol to accommodate wireless access to Internet • Wireless Application Protocol (WAP) • Provides mobile users access to telephony and information services including Internet and Web • Includes wireless phones, pagers and personal digital assistants (PDAs) Hung Nguyen, TCOM 552, Fall 2006

  11. Chapter 11: Cordless Systems and Wireless Local Loop • Cordless systems • Wireless local loop (WLL) • Sometimes called radio in the loop (RITL) or fixed wireless access (FWA) Hung Nguyen, TCOM 552, Fall 2006

  12. Chapter 10: Cellular Wireless Networks • Cellular wireless network design issues • First generation analog (traditional mobile telephony service) • Second generation digital cellular networks • Time-division multiple access (TDMA) • Code-division multiple access (CDMA) • Third generation networks Hung Nguyen, TCOM 552, Fall 2006

  13. Introduction to Wireless

  14. Wireless Comes of Age • Marconi invented the wireless telegraph in 1896 • Communication by encoding alphanumeric characters in analog electromagnetic signal • Sent telegraphic signals across the Atlantic Ocean • Communications satellites launched in 1960s • Before 1980’s: wireless technology usage • Radio, television, communication satellites, paging • More recently • Cellular services started in early 1980’s in the US • Wireless data at low rates available in the 1990’s (e.g., ARDIS, Bell South), higher data rates underway • WLAN came of age in late 1990’s, WiFi hotspots Hung Nguyen, TCOM 552, Fall 2006

  15. Cellular/PCS Evolution • Bell Labs proposes cellular in 1968 • First cellular system begins operation in early 1980’s using analog (AMPS) system, by ATT -- First Generation systems (1G) --’Cellular’ • These are called cellular systems, in the 800 and 900 MHz range mostly. Large, bulky phones • Digital system using TDMA starts early 1990’s (2G) • Both in 800 and 900 MHz, and around 1800 and 1900 MHz • These, along with GSM and CDMA below, labeled PCS, when in the 1800 and 1900 MHz range Hung Nguyen, TCOM 552, Fall 2006

  16. Cellular/PCS Evolution (Cont’d) • European GSM starts operation early 1990’s (2G) • Similar frequency range as TDMA but not exactly--- US and Europe usually differ • GSM used nearly worldwide, more users than US standards -- in US Voicestream uses it • First CDMA operation 1996-1997 -- Qualcomm holds ‘key’ patents (2G) • Used by half of 2G systems in US, S. Korea, parts of Latin America • First (very) limited 3G operation in Japan in May 2001- Wideband CDMA • Worldwide (semi) standardization agreed to in 1999, for data rate services to 2 Mbps • Frequency allocation around 1800 MHz in most of world, US just set 90 MHz • 2.5G, in the form of GPRS (GSM/TDMA) and 1XRTT (IS-95) out in 02 • Some pictures, higher data rates Hung Nguyen, TCOM 552, Fall 2006

  17. Mobile Comms -- Anywhere/Anytime • Personal Communications -- Inexpensive use of cellular and wireless to communicate anywhere, anytime --- Personal: for individual use • Cellular in 1983 was expensive, PCS in 90’s it became cheap, commonplace • Terms: Wireless, Mobile, PCS, etc • Comms for access to people (voice) and information (data, services) • Essential Requirements • Mobility >>> untethered >>> wireless • Mobility also meant having access to the network (the PSTN) -- will get you anywhere • Personal (e.g., not just corporate) >>> cheap small terminals, cheap services Hung Nguyen, TCOM 552, Fall 2006

  18. Mobile Comms -- Anywhere/Anytime (cont’d) • Essential Ingredients • Infrastructure (Comms systems and networks) • User terminals (for personal use) • Standards (multiple systems need to interoperate) • Spectrum (availability and use) • Services (over the infrastructure) --- From voice to smart phones to data -- value added • Subscribers (enough to make it financially attractive) Hung Nguyen, TCOM 552, Fall 2006

  19. CATEGORIES OF MOBILITY Mobile Untethered Portable Transportable In Building Wireless LAN Hung Nguyen, TCOM 552, Fall 2006

  20. Wireless Examples • Mobile wireless systems • Cellular/PCS (Personal Communications Systems) • Terrestrial microwave transmission • Satellite transmission • Broadcast radio and TV • Fixed wireless • WLAN • Paging • Wireless Data • Including email/Web/News/Video on personal units Hung Nguyen, TCOM 552, Fall 2006

  21. Limitations and Issues in Wireless Technologies • Political and economic limitations affect wireless technologies • Spectrum limitations, infrastructure costs, standards, politics and policies • Spectrum is limited, best portions allocated, expensive --- legal/political • 3G US spectrum a problem, 90 MHz to be reallocated from DOD/MDS (asked for more) • NextWave bought for $5B, bankrupt, FCC sold spectrum for $16B, lost in court, still in litigation, asked to be relieved of debt burden • Expensive infrastructure (15K base stations) needed for national coverage Hung Nguyen, TCOM 552, Fall 2006

  22. Limitations and Issues in Wireless Technologies (cont’d) • Standards evolve slowly, require international consensus, and involve multiple incompatible variants --- seamless roaming is not always possible • Telecom infrastructure and industry are important national policy issues • Current wireless woes: low market valuations due to very competitive cellular market, debt burdens, too many carriers, expensive/limited spectrum, wireless data build up is expensive and unprofitable • Technical • Wireless propagation is error prone and forces complex radio equipment • Small devices for mobility, hard on technology and battery Hung Nguyen, TCOM 552, Fall 2006

  23. Mobile Telephone & Internet Users Millions Mobile Telephone Users Internet Users Source: Ericsson Radio Systems, Inc. Year BUT: SLOWED DOWN, OVERHYPED, AND ARPU IS DOWN Hung Nguyen, TCOM 552, Fall 2006

  24. 137,458,902 currentU.S. Wireless Subscribers Aug. 24, 2002, 2AM, per CTIA From CTIA site http://www.wow-com.com /industry/stats/surveys/ NOTE: Subscribers, Cell Sites, ARPU Hung Nguyen, TCOM 552, Fall 2006

  25. From CTIA web site Hung Nguyen, TCOM 552, Fall 2006

  26. From CTIA web site Hung Nguyen, TCOM 552, Fall 2006

  27. From CTIA web site Hung Nguyen, TCOM 552, Fall 2006

  28. Other Wireless Status Data • Wireless companies market cap • March 2000 --- $794B • March 2001 --- $265B • Wireless industry layoffs, Dec.2000-Jan2002: 352,000 • Wireless subscribers still growing, but slower • Sales in one year period expected at 540 million handsets down to less than 400 million, globally • DOCOMO (Japan) continues to add subscribers, including iMode (Internet) accounts -- ARPU is $71.86, much higher than in US • China to have 132 million wireless users by the end of2001, a gain of 46.4 million over a year before, 2nd to the US, Europe about 100 million -- Asia Pacific biggest growth area Hung Nguyen, TCOM 552, Fall 2006

  29. Nokia 3G Concept Phone---Where Cellular Might Be Going--- Nokia concept phone, from http://www.3g-generation.com/index.htm Hung Nguyen, TCOM 552, Fall 2006

  30. Mobile Wireless Data Services • Mobile messaging, two way paging, email/news • e.g., Motorola 2-way, Blackberry RIM, other specialized services • Mobile cell-phone-based data • Currently on WAP enabled phones (messaging, news, sports, wireless Internet promise) • iMode in Japan --- better/faster, growing use • SMS based on GSM in Europe --- messaging • Coming: GPRS-based and 1xRTT-based services to few 10’s Kbps -- wireless Internet, email, pictures, etc • Later higher with EDGE, and to 2 Mbps with 3G (Europe Japan first, later in US) -- 3G will do all services above plus voice and video simultaneously • WLAN -- WiFi spreading like a virus, many public AP’s • Some say it will do VOIP, go mobile/wide-area, do away with 3G Hung Nguyen, TCOM 552, Fall 2006

  31. Public WLAN Service: Mobile Operators Must not Miss the Boat (#IN020286MD) Hung Nguyen, TCOM 552, Fall 2006

  32. Broadband Wireless Technology • Higher data rates obtainable with mobile broadband wireless technology • Broadband = more than messaging or paging or voice • Fixed broadband wireless --- to home/office, Internet • But mobile applications more difficult --- GPRS 1st • Shares same advantages of all wireless services: convenience and reduced cost • Service can be deployed faster than other fixed service • No cost of cable plant • But so far not a commercial success (some exceptions), service is spotty for wireless data Hung Nguyen, TCOM 552, Fall 2006

  33. Why Is Wireless Different? • Why is there a ‘send’ or ‘call’ button on a cell phone? • Why can’t you make a cell phone call from some places? • Why does a cell connection break up sometimes? • Why does a cell phone battery last less time than a pager battery? • Why are cell phone calls becoming cheaper? Hung Nguyen, TCOM 552, Fall 2006

  34. Cellular System Overview Hung Nguyen, TCOM 552, Fall 2006

  35. Why is Mobile Wireless Difficult? • Coverage limitations (blank spots in coverage, shielding in buildings, shadowing) • Signal losses and fading, due to propagation, blockage, and multipath, while still or while moving (lower received signal power, causes bit errors, lower voice quality, can fade out) • Call blocking, due to having no available channel (number of channels in a cell, busy hours, busy spots) • Small user terminals desired, battery (talktime, ontime, and lifetime) • Infrastructure (base stations and switches) needs to be built up and connected to phone network --- expensive • Spectrum needs to be acquired --- expensive Hung Nguyen, TCOM 552, Fall 2006

  36. From iec.org Hung Nguyen, TCOM 552, Fall 2006

  37. Hung Nguyen, TCOM 552, Fall 2006 From Rappaport & Ref. there

  38. Wireless -- The Technical Good News • Radio propagation effects can be offset • Use of modulation, coding and processing techniques • Continuously improving techniques (e.g., smart antennas) • Coverage can be expanded and filled in with additional base stations (if there are enough customers to pay for it) • Battery power is sufficient because of highly power efficient techniques and power control in most units • Problems persist for higher data rates, such a 3G • Spectrum allocations do exist and additional spectrum is/will be auctioned off or allocated • Standards do exist and large areas allow roaming • Current infrastructure works OK for voice (mostly), data expansion underway Hung Nguyen, TCOM 552, Fall 2006

  39. Typical Cellular Numbers • Base Station Transmitted Power: 10-100 watts (= 20 dBW = 50 dBm) • Base Station Antenna Gains: 10-17 dB (i.e., X10-50) • US: Base stations: about 100K --- Users: 130M • Voice Transmission BW or Data Rates: • Analog (FM): 25 or 30 KHz • Digital: 8-14 Kbps • 3 dB = X2; 10 dB = X10; 20 dB = X100; 30 dB = X1000; 100 dB = X10,000,000,000 (or 10^10 = 10 Billion) • Receiver Sensitivities: -100 to -117 dBm (dB below a milliwatt) (-100 dBm = 10^-10 mW) -- pretty good ah!! • Propagation Losses: 80-180 dB over 1-10 kms • US Cellular and PCS Frequencies: 824-894 MHz, and 1850-1990 MHz Hung Nguyen, TCOM 552, Fall 2006

  40. Source: Ericsson Radio Systems, Inc. Hung Nguyen, TCOM 552, Fall 2006

  41. Books • Stallings • Online resources at www.WilliamStallings.com/Wireless1e.html • Has signals and comms basics, comms technical topics on modulation, coding, spread spectrum, others • Has cellular and other wireless topics such as satellite and WLAN • Not deep into cellular/mobile topics, but good introduction for TCOM major • Rappaport • More technical than Stallings. Often used for EE major • Deeper into cellular and mobile and much more physical layer • A bit dry and a good reference for working engineer • Lee • Preceded Rappaport and provided mathematical and theoretical foundation for mobile communications Hung Nguyen, TCOM 552, Fall 2006

  42. Some Internet and Web Resources • Web page for Stallings Book • WilliamStallings.com/Wireless1e.html • Useful web sites, errata sheet, figures, tables, slides, internet mailing list, wireless courses • Wireless devices and items http://www.zdnet.com/special/filters/wireless/ • Web proforum telecom, wireless and other simple tutorials http://www.iec.org/online/tutorials/ • Washington area centric, telecom at http://www.washtech.com/news/telecom/ • Qualcomm CDMA Technology Home Page at http://www.cdmatech.com/ • Regulatory: FCC and ITU at www.fcc.gov and www.itu.int • Wireless News --- wirelessweek.com • CTIA --- http://www.wow-com.com/ • More Complete Online References, next page Hung Nguyen, TCOM 552, Fall 2006

  43. Online References (cont’d) • http://comet.columbia.edu/cellularip/ Cellular IP protocol research • http://delson.org/wc/ 3G Wireless Conference • http://www.tiaonline.org/ Telecom Industry Association • http://www.thestandard.com/section/0,1970,813,00.html The Industry Standard, on Tech and Telecomm, Latest • http://www.openwave.com/ Makers of WAP wireless phone microbrowser • http://www.itu.int/home/index.html ITU page on IMT2000 • http://www.3gpp2.org/ 3G Partnership consortia – 2 (1 was Europe, 2 US) • http://www.ietf.org/html.charters/wg-dir.htmlActive IETF Working Groups • http://www-daedalus.cs.berkeley.edu/ Berkeley wireless project • More Complete Online References, next page Hung Nguyen, TCOM 552, Fall 2006

  44. Online References (cont’d) • http://www.ieee-wcnc.com/ IEEE Wireless Comms and Networking Conference • http://www.sss-mag.com/ Online spread spectrum and RF magazine • http://www.analysys.com/vlib/ Virtual library, telecomunications • Wireless Design Online (Review site in general – 'a vertical net marketplace for industry professionals') http://www.wirelessdesignonline.com/content/hubs/dir.asp?hub=news • http://www.iec.org/tutorials/cell_comm/index.html Tutorials, this one on cellular communications • http://www.washtech.com/news/telecom/ Washington Tech online, Latest • http://www.zdnet.com/enterprise/filters/resources/0,10227,6016597,00.html zdNet wireless resources • http://www.cdmatech.com/ Qualcomm CDMA Technology Home Page Hung Nguyen, TCOM 552, Fall 2006