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Wireless Technologies

Discover the world of wireless technologies, from cellular communications to satellite systems and Wireless LAN. Understand the advantages and challenges of mobility support and Wireless applications.

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Wireless Technologies

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  1. Wireless Technologies

  2. Outline • Wireless technology overview • Cellular communications • Satellite systems • Wireless LAN • 802.11, Bluetooth, UWB • Mobility support • WAP • Wireless applications

  3. Why Wireless? • Human freedom • Portability v. Mobility • Objective: “anything, anytime, anywhere” • Mobility • Size, weight, power • Functionality • Content • Infrastructure required • Cost • Capital, operational

  4. Worldwide Mobile Subscribers SOURCE: CTIA, iGillottResearch, 2001

  5. 4G CELLULAR 56-100 GHz 3G CELLULAR 1.5-5.2 GHz 1G, 2G CELLULAR 0.4-1.5GHz Electromagnetic Spectrum HARMFUL RADIATION LIGHT RADIO SOUND VHF = VERY HIGH FREQUENCY UHF = ULTRA HIGH FREQUENCY SHF = SUPER HIGH FREQUENCY EHF = EXTRA HIGH FREQUENCY UWB 3.1-10.6 GHz SOURCE: JSC.MIL

  6. MARITIME MOBILE FIXED BROADCAST MOBILE AERO RADIOLOCATION

  7. Wireless Telephony WIRELESS AIR LINK WIRED PUBLIC SWITCHED TELEPHONE NETWORK SOURCE: IEC.ORG

  8. ACTUAL COVERAGE AREA OF CELL 3 ACTUAL COVERAGE AREA OF CELL 1 Cell Clusters CELL 1 OVERLAPS 6 OTHERS DIFFERENT FREQUENCIES MUST BE USED IN ADJACENT CELLS SEVEN DIFFERENT SETS OF FREQUENCIES REQUIRED SOURCE: IEC.ORG

  9. Space Division Multiple Access (SDMA) MANY CELLS CAN SHARE SAME FREQUENCIES IF SEPARATED IN SPACE PATTERN CAN BE REPLICATED OVER THE ENTIRE EARTH 200 FREQUENCIES IN ONE CELL TOTAL NUMBER OFFREQUENCIES = 1400 WORLDWIDE

  10. Cell Handover AS PHONE MOVES FROM CELL “A” TO CELL “B”: • CELL “A” MUST HAND THE CALL OVER TO “B” • PHONE MUST CHANGE FREQUENCIES • CELL “A” MUST STOP TRANSMITTING Minimum performance contour A x y B z Handover threshold contour ANIMATION SOURCE: R. C. LEVINE, SMU

  11. MACROCELL: $1M FAST-MOVINGSUBSCRIBERS PICOCELLS MICROCELL: $250K SLOW-MOVINGSUBSCRIBERS Cell Sizes GSM: 100m - 50 km 250 km/hr

  12. Multiple Access • Many users sharing a resource at the “same time” • Needed because user must share cells • FDMA (frequency division) • Use different frequencies • TDMA (time division) • Use same frequency, different times • CDMA (code division) • Use same frequency, same time, different “codes”

  13. k1 k2 k3 k4 k5 k6 c f t Frequency Division Multiplexing (FDMA) Each channel gets a band (range) of frequencies Used in traditional radio, TV, 1G cellular Advantages: • No dynamic coordination Disadvantages: • Inflexible & inefficient if channel load is dynamic and uneven EACH CHANNEL OCCUPIES SAME FREQUENCY AT ALL TIMES SOURCE: NORMAN SADEH

  14. k1 k2 k3 k4 k5 k6 c FREQUENCY BAND f t Time Division Multiplexing (TDMA) Each channel gets entire spectrum for a certain (rotating) time period Advantage: Can assign more time to senders with heavier loads 3X capacity of FDMA, 1/3 of power consumption Disadvantage: Requires precise synchronization SOURCE: NORMAN SADEH

  15. k1 k2 k3 k4 k5 k6 c f t Combining TDMA and FDMA Each channel gets a certain frequency band for a certain amount of time. Example: GSM • Advantages: • More robust against frequency- selective interference • Much greater capacity with time compression • Inherent tapping protection • Disadvantages • Frequency changes must be coordinated SOURCE: NORMAN SADEH

  16. Time-Division Multiple Access SOURCE: QUALCOMM

  17. k1 k2 k3 k4 k5 k6 c f t Code Division Multiplexing (CDMA) • Each channel has unique“code” • All channels use same spectrumat same time but orthogonal codes • Advantages: • bandwidth efficient – code space is huge • no coordination or synchronizationbetween different channels • resists interference and tapping • 3X capacity of TDMA, 1/25 power consumption • Disadvantages: • more complex signal regeneration • Implemented using spread spectrum

  18. Cellular Generations • First • Analog, circuit-switched (AMPS) • Second • Digital, circuit-switched (GSM, Palm) 10 Kbps • Advanced second • Digital, circuit switched, Internet-enabled (WAP) 10 Kbps • 2.5 • Digital, packet-switched, TDMA (GPRS, EDGE)40-400 Kbps • Third • Digital, packet-switched, wideband CDMA (UMTS)0.4 – 2 Mbps • Fourth • Data rate 100 Mbps; achieves “telepresence”

  19. CELL TRANSMITTER & RECEIVER INTERFACE TO LANDTELEPHONE NETWORKS HIERARCHY OF CELLS STOLEN, BROKEN CELLPHONE LIST LIST OF ROAMINGVISITORS PHONE ENCRYPTION, AUTHENTICATION LIST OF SUBSCRIBERS IN THIS AREA SIM: IDENTIFIES A SUBSCRIBER GSM Architecture DATA RATE: 9.6 Kbps SOURCE: UWC

  20. SMS – Short Message Service • Integral part of GSM standard • Added to other standards as well • Uses control channel of phone • Send/Receive short text messages • Sender pays (if from mobile phone) • Phone has "email" address • SMTP Interface • Only in the US, not the rest of the world • Allows messages to be sent for free! • 3125551234@wireless.att.net • 1 BILLION SMS/day worldwide SOURCE: GEMBROOK SYSTEMS

  21. Bank Web Site Customer Internet Alert me to all credit card transactions greater than $100. Message from YourBank: Credit card purchase of $1245 at Joe’s HiFi. Bank Back-end Systems SMS Monitoring Application Air Credit card used Joe’s HiFi $1245 Message appears within seconds on the customer’s phone Wireless Carrier SMS Carrier Cell Tower SMS in Banking SOURCE: GEMBROOK SYSTEMS

  22. GEO MEO LEO Satellite Systems GEO (22,300 mi., equatorial) high bandwidth, power, latency MEO high bandwidth, power, latency LEO (400 mi.) low power, latency more satellites small footprint V-SAT (Very Small Aperture) private WAN SATELLITE MAP SOURCE: WASHINGTON UNIV.

  23. Geostationary Orbit SOURCE: BILL LUTHER, FCC

  24. GPS Satellite Constellation • Global Positioning System • Operated by USAF • 28 satellites • 6 orbital planes at a height of 20,200 km • Positioned so a minimum of 5 satellites are visible at all times • Receiver measures distance to satellite SOURCE: NAVSTAR

  25. GPS Trilateration DISTANCE MEASUREMENTS MUST BE VERY PRECISE LIGHT TRAVELS 1018 FEET EACH MICROSECOND SOURCE: PETER DANA

  26. Automatic Vehicle Location (AVL) • Benefits of AVL • Fast dispatch • Customer service • Safety, security • Digital messaging • Dynamic route optimization • Driver compliance • Sample AVL Users • Chicago 911 • Inkombank, Moscow • Taxi companies Intelligent Highway demo CA SOURCE: TRIMBLE NAVIGATION

  27. Location-Aware Applications • Vehicle tracking • Firemen in buildings, vital signs, oxygen remaining • Asset tracking • Baggage • Shoppers assistance • Robots • Corporate visitors • Insurance • Barges

  28. Wireless LAN • Idea: just a LAN, but without wires • Not as easy since signals are of limited range • Unlike wired LAN, if A can hear B and B can hear C, not necessarily true that A can hear C • Uses unlicensed frequencies, low power • 802.11 from 2 Mb to 54 Mb • Bluetooth • UWB

  29. Wireless LAN Components Extended Range Antenna WaveLAN ISA (Industry Standard Architecture) Card WavePOINT II Transmitter Ethernet Converter 11 Mbps WaveLAN PCMCIA Card SOURCE: LUCENT

  30. Wireless LAN Configurations CLIENT AND ACCESS POINT WIRELESS PEER-TO-PEER BRIDGING WITH DIRECTIONAL ANTENNAS MULTIPLE ACCESS POINTS + ROAMING UP TO 17 KM ! SOURCE: PROXIM.COM

  31. Bluetooth A standard permitting for wireless connection of: • Personal computers • Printers • Mobile phones • Handsfree headsets • LCD projectors • Modems • Wireless LAN devices • Notebooks • Desktop PCs • PDAs

  32. Bluetooth Characteristics • Operates in the 2.4 GHz Industrial-Scientific-Medical (ISM) (unlicensed)! band. Packet switched. 1 milliwatt (as opposed to 500 mW cellphone. Low cost. • 10m to 100m range • Uses Frequency Hop (FH) spread spectrum, which divides the frequency band into a number of hop channels. During connection, devices hop from one channel to another 1600 times per second • Bandwidth 1-2 megabits/second • Supports up to 8 devices in a piconet (two or more Bluetooth units sharing a channel). • Built-in security. • Non line-of-sight transmission through walls and briefcases. • Easy integration of TCP/IP for networking.

  33. Bluetooth Devices ALCATEL One TouchTM 700 GPRS, WAP ERICSSON R520 GSM 900/1800/1900 ERICSSON BLUETOOTH CELLPHONE HEADSET NOKIA 9110 + FUJI DIGITAL CAMERA ERICSSON COMMUNICATOR

  34. Bluetooth Piconets • Piconet = small area network • “Ad hoc” network: no predefined structure • Based on available nodes and their locations • Formed (and changed) in real time

  35. Scatternet Piconets Master Bluetooth Scatternets Master / Slave Slave Piconet ScatterNet SOURCE: KRISHNA BHOUTIKA

  36. “0” “1” 500 ps d d Frequency (GHz) Randomized Time Coding d = 125 ps 0 -40 Power Spectral Density (dB) Amplitude Random noise signal Time -80 Frequency (GHz) 1 2 3 4 5 Time-Modulated Ultra-Wideband (TM-UWB) • Not a sinewave, but millions of pulses per second • Time coded to make noise-likesignal • Pulse position modulation Spread Spectrum SOURCE: TIME DOMAIN

  37. PulsON, A Chip Based Solution Ultra Wideband Properties • VERY low power: 0.01 milliwatt • Bluetooth 1 milliwatt (100 x UWB) • Cellphone 500 milliwatts (50,000 x UWB) • Range: 30 to 300 feet • Very small • Low cost • 100 Mbits/second • Up to 500 Mbps for short distances(USB speed) • No interference • Secure

  38. Wireless Application Support • WAP (Wireless Application Protocol) and iMode • High-level protocols that use cellular transport • WAP: • Uses WML (Wireless Markup Language) • Divides content into “cards” equal to one telephone screen • Simplified but incompatible form of HTML • To send to a WAP phone, must broadcast WML content

  39. Internet MobileNetwork WAP Applications Web Content Server Non Mobile Internet User WAP Gateway Mobile Terminal iNexware Database Server WAP simulator SOURCE: DANET

  40. iMode • Telephone, pager, email, browser, location tracking, banking, airline tickets, entertainment tickets, games • NTT DoCoMo (ドコモ means “anywhere”) • Japan is the wireless Internet leader: iMode FAQ SOURCE: EUROTECHNOLOGY JAPAN K.K.

  41. iMode • Sits on top of packet voice/data transport • As of July 31, 2003, > 39 million subscribers • 28,000 new ones per day • 26% of Japan • >3000 “official” sites • >1000 application partners • >40,000 unofficial sites • Fee based on amountof data transmitted SOURCES: XML.COM, EUROTECHNOLOGY.COM

  42. iMode • Phonetic text input (better for Japanese) • SLOW: 9.6 Kbps, but 3G will raise to 384 K • Uses cHTML (compact HTML) • same rendering model as HTML (whole page at a time) • low memory footprint (no tables or frames) • Standby time: 400 min., device weight 2.4 oz. (74g) SOURCES: XML.COM, NTT

  43. BILLING DB INTERNET INFO PROVIDER USER DB IP IP iMode Operation DoCoMo Packet Network (PDC-P) iMode Servers HTTP PACKET DATA SOURCE: SAITO & SHIN

  44. Wireless Standards • 802.11b (2.4 GHz 300’ radius 11 Mbps) • 802.11a (5 GHz 54 Mbps incompatible with b) • 802.11g (2.4 GHz 54 Mbps backward compatible with b) • 802.20 (<3.5 GHz >1 Mbps @250 kph) • BlueTooth (2.4 Ghz 30’ radius) • GSM (9.6 Kbps) GPRS (28.8 Kbps up to 60 Kbps ) • 3G (UMTS 1.1 Mbit/s shared typically giving 80 Kbit/s ) • 4G2010? (10 Mbs? ) • UWB potential to deliver 500 Mbps over short distances SOURCE: JOHN DOWNARD

  45. Key Takeaways • Mobile growing very rapidly • Cell systems need large infrastructure • Wireless LAN does not • Content preparation is a problem • Wireless business models largely unexplored • Bandwidth, bandwidth, bandwidth

  46. Q A &

  47. DATA 1 0 1 “CODE” 0 1 0 1 0 0 1 0 0 0 1 0 1 1 0 0 1 1 DATA  CODE 1 0 1 0 1 1 1 0 0 0 1 0 0 0 1 1 0 0 +1 ACTUAL SIGNAL -1 Code Division SOURCE: JOCHEN SCHILLER

  48. DATA B 1 0 0 “CODE” B 0 0 0 1 1 0 1 0 1 0 0 0 0 1 0 1 1 1 DATA  CODE 1 1 1 0 0 1 1 0 1 0 0 0 0 1 0 1 1 1 +1 ACTUAL SIGNAL B -1 Code Division SOURCE: JOCHEN SCHILLER

  49. +1 ACTUAL SIGNAL B -1 +1 ACTUAL SIGNAL A -1 Two CDMA Signals +2 ACTUAL SIGNAL A+B -2 SOURCE: JOCHEN SCHILLER

  50. +2 ACTUAL SIGNAL A+B -2 “CODE” A 0 1 0 1 0 0 1 0 0 0 1 0 1 1 0 0 1 1 Recovering Data A From A+B +1 -1 +2 -(A+B) * CODE A -2 0 INTEGRAL 1 1 SOURCE: JOCHEN SCHILLER

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