CS434/534: introduction

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  • We are getting closer to the goal because of advances in enabling technologies.
  • Service composition: when playing movie, send sound to stereo When laptop is active, turn down the volume of the TV
  • Vehicles transmission of news, road condition, weather, music via DAB personal communication using GSM position via GPS local ad-hoc network with vehicles close-by to prevent accidents, guidance system, redundancy vehicle data (e.g., from busses, high-speed trains) can be transmitted in advance for maintenance Emergencies early transmission of patient data to the hospital, current status, first diagnosis replacement of a fixed infrastructure in case of earthquakes, hurricanes, fire etc. crisis, war, ...
  • $22 billion: Amount operators paid the U.S. government over the past ten years for spectrum. Source Burton Group.
  • $22 billion: Amount operators paid the U.S. government over the past ten years for spectrum. Source Burton Group.
  • CS434/534: introduction

    1. 1. CS43 4 /53 4 : Mobile Computing and Wireless Networks http://zoo.cs.yale.edu/classes/cs43 4/ Y. Richard Yang 01 /13/2009
    2. 2. Outline <ul><li>Introduction to wireless networks and mobile computing </li></ul><ul><li>Challenges facing wireless networks and mobile computing </li></ul><ul><li>Course information </li></ul><ul><li>Introduction to wireless physical layer </li></ul>
    3. 3. Goal of Wireless Networking and Mobile Computing <ul><li>“ People and their machines should be able to access information and communicate with each other easily and securely, in any medium or combination of media – voice, data, image, video, or multimedia – any time, anywhere, in a timely, cost-effective way.” </li></ul>Dr. G. H. Heilmeier, Oct 1992
    4. 4. Enabling Technologies <ul><li>Development and d eployment of wireless/mobile technology and i nfrastructure </li></ul><ul><ul><li>i n-room, in-building, on-campus, in-the-field, MAN, WAN </li></ul></ul><ul><li>Miniaturization of c omputing m achinery </li></ul><ul><li>. . . -> PCs -> laptop -> PDAs/smart phones -> embedded computers /sensors </li></ul><ul><li>Improving device capabilities/software development environments, e.g., </li></ul><ul><ul><li>andriod: http://code.google.com/android/ </li></ul></ul><ul><ul><li>iphone: http://developer.apple.com/iphone/ </li></ul></ul><ul><ul><li>windows mobile </li></ul></ul>
    5. 5. Pervasive Use of Mobile Wireless Devices <ul><li>There are ~4 billion mobile phones </li></ul><ul><ul><li>Over 50 countries have mobile phone subscription penetration rates higher than that of the population (Infoma 2007) </li></ul></ul><ul><ul><li>http://en.wikipedia.org/wiki/Mobile_phone_penetration_rate </li></ul></ul><ul><li>The mobile device will be the primary connection tool to the Internet for most people in the world in 2020. PEW Internet and American Life Project, Dec. 2008 </li></ul>
    6. 6. At Home WiFi WiFi WiFi cellular bluetooth UWB satellite WiFi 802.11g/n
    7. 7. At Home Source: http://teacher.scholastic.com/activities/science/wireless_interactives.htm
    8. 8. At Home: Last-Mile <ul><li>Many users still don’t have broadband </li></ul><ul><ul><li>reasons: out of service area; some consider expensive </li></ul></ul><ul><li>Broadband speed is still limited </li></ul><ul><ul><li>DSL: 1-6 Mbps download, and 100-768Kbps upload </li></ul></ul><ul><ul><li>Cable modem: depends on your neighbors </li></ul></ul><ul><ul><li>Insufficient for several applications (e.g., high-quality video streaming) </li></ul></ul>
    9. 9. On the Move Source: http://www.ece.uah.edu/~jovanov/whrms/
    10. 10. On the Move: Context-Aware Source: http://www.cs.cmu.edu/~aura/docdir/sensay_iswc.pdf
    11. 11. On the Road ad hoc GSM/UMTS, cdmaOne/cdma2000, WLAN, GPS DAB, TETRA, ... road condition, weather, location-based services, emergency
    12. 12. Example: IntelliDrive (Vehicle Infrastructure Integration) <ul><li>Traffic crashes resulted in more than 41,000 lives lost in 2007 </li></ul><ul><li>Establishing vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I) and vehicle-to-hand-held-devices (V2D) communications </li></ul><ul><ul><li>safety: e.g., intersection collision avoidance/violation warning/turn conflict warning, curve warning </li></ul></ul><ul><ul><li>mobility: e.g., crash data, weather/road surface data, construction zones, emergency vehicle signal pre-emption </li></ul></ul>More info: http://www.its.dot.gov/intellidrive/index.htm
    13. 13. Collision Avoidance : V2V Networks <ul><li>stalled vehicle warning </li></ul>http://www.gm.com/company/gmability/safety/news_issues/releases/sixthsense_102405.html <ul><li>bland spots </li></ul>
    14. 14. Collision Avoidance at Intersections <ul><li>Two million accidents at intersections per year in US </li></ul>Source: http://www.fhwa.dot.gov/tfhrc/safety/pubs/its/ruralitsandrd/tb-intercollision.pdf
    15. 15. Mobile and W ireless S ervices – Always Best Connected UMTS, DECT 2 Mbit/s UMTS Rel. 6 400 kbit/s LAN 100 Mbit/s, WLAN 54 Mbit/s UMTS Rel. 5 400 kbit/s GSM 115 kbit/s, WLAN 11 Mbit/s GSM 53 kbit/s Bluetooth 500 kbit/s GSM/EDGE 135 kbit/s, WLAN 780 kbit/s LAN, WLAN 780 kbit/s
    16. 16. Disaster Recovery/Military <ul><li>9/11, Tsunami, Hurricane Katrina, South Asian earthquake … </li></ul><ul><li>Wireless communication and mobile computing capability can make a difference between life and death ! </li></ul><ul><ul><li>rapid deployment </li></ul></ul><ul><ul><li>efficient resource and energy usage </li></ul></ul><ul><ul><li>flexible: unicast, broadcast, multicast, anycast </li></ul></ul><ul><ul><li>resilient: survive in unfavorable and untrusted environments </li></ul></ul>http://www.att.com/ndr/
    17. 17. Habitat Monitoring: Example on Great Duck Island A 15-minute human visit leads to 20% offspring mortality Patch Network Transit Network Basestation Gateway
    18. 18. Wireless and Mobile Computing <ul><li>Driven by t echnology and v ision </li></ul><ul><ul><li>w ireless communication technology </li></ul></ul><ul><ul><li>g lobal infrastructure </li></ul></ul><ul><ul><li>d evice miniaturization </li></ul></ul><ul><ul><li>mobile computing platforms </li></ul></ul><ul><li>The f ield is m oving f ast </li></ul>
    19. 19. Why is the Field Challenging?
    20. 20. Challenge 1: Unreliable and Unpredictable Wireless Coverage What Robert Poor (Ember) calls “The good, the bad and the ugly” <ul><li>Wireless links are not reliable: they may vary over time and space </li></ul>Asymmetry vs. Power Reception v. Distance * Cerpa, Busek et. al
    21. 21. Challenge 2: Open Wireless Medium <ul><li>Wireless interference </li></ul>S1 S2 R1 R1
    22. 22. Challenge 2: Open Wireless Medium <ul><li>Wireless interference </li></ul><ul><li>Hidden terminals </li></ul>S1 S2 R1 R1 S1 R1 S2
    23. 23. Challenge 2: Open Wireless Medium <ul><li>Wireless interference </li></ul><ul><li>Hidden terminals </li></ul><ul><li>Exposed terminal </li></ul>S1 S2 R1 R1 S1 R1 S2 R1 S1 S2 R2
    24. 24. Challenge 2: Open Wireless Medium <ul><li>Wireless interference </li></ul><ul><li>Hidden terminals and </li></ul><ul><li>Exposed terminal </li></ul><ul><li>Wireless security </li></ul><ul><ul><li>eavesdropping, denial of service, … </li></ul></ul>S1 S2 R1 R1 S1 R1 R2 R1 S1 S2 R2
    25. 25. Challenge 3: Mobility <ul><li>Mobility causes poor-quality wireless links </li></ul><ul><li>Mobility causes intermittent connection </li></ul><ul><ul><li>under intermittent connected networks, traditional routing, TCP, applications all break </li></ul></ul><ul><li>Mobility changes context, e.g., location </li></ul>
    26. 26. Challenge 4: Portability <ul><li>Limited battery power </li></ul><ul><li>Limited processing, display and storage </li></ul><ul><li>Mobile phones </li></ul><ul><li>voice, data </li></ul><ul><li>simple graphical displays </li></ul><ul><li>GSM/3G </li></ul><ul><li>Laptop </li></ul><ul><li>fully functional </li></ul><ul><li>standard applications </li></ul><ul><li>battery; 802.11 </li></ul>P erformance /Weight/Power Consumption Sensors, embedded controllers <ul><li>PDA phone </li></ul><ul><li>data </li></ul><ul><li>simpler graphical displays </li></ul><ul><li>802.11/3G </li></ul>
    27. 27. Challenge 5: Changing Regulation and Multiple Communication Standards cellular phones satellites wireless LAN cordless phones 1992: GSM 1994: DCS 1800 2001: IMT-2000 1987: CT1+ 1982: Inmarsat-A 1992: Inmarsat-B Inmarsat-M 1998: Iridium 1989: CT 2 1991: DECT 199x: proprietary 1997: IEEE 802.11 1999: 802.11b, Bluetooth 1988: Inmarsat-C analogue digital 1991: D-AMPS 1991: CDMA 1981: NMT 450 1986: NMT 900 1980: CT0 1984: CT1 1983: AMPS 1993: PDC 2000: GPRS 2000: IEEE 802.11a Fourth Generation (Internet based)
    28. 28. Evolution of Mobile Systems to 3G
    29. 29. 3G Networks http://en.wikipedia.org/wiki/List_of_mobile_network_operators_of_the_Americas#United_States
    30. 30. What Will We Cover?
    31. 31. Class Info: Personnel <ul><li>I nstructor </li></ul><ul><ul><li>Y. Richard Yang, yry@cs.yale.edu, AKW 308A </li></ul></ul><ul><ul><li>office hours: to be posted </li></ul></ul><ul><li>T eaching fellow </li></ul><ul><ul><li>Richard Alimi, richard.alimi @yale.edu, AKW 303 </li></ul></ul><ul><ul><li>office hours: to be posted on class page </li></ul></ul><ul><li>Course home page </li></ul><ul><ul><li>http://zoo.cs.yale.edu/classes/cs434/ </li></ul></ul>
    32. 32. Class Goals <ul><li>Learn both fundamentals and applications of wireless networking and mobile computing </li></ul><ul><li>Obtain hands-on experience on developing on mobile, wireless devices </li></ul><ul><li>Discuss challenges and opportunities in wireless networking and mobile computing </li></ul>
    33. 33. The Layered R eference Model Application Transport Network Data Link Physical Medium Data Link Physical Application Transport Network Data Link Physical Data Link Physical Radio Often we need to implement a function across multiple layers. Network Network
    34. 34. Course Topics <ul><li>Communications: </li></ul><ul><ul><li>physical layer: channel and diversity </li></ul></ul><ul><ul><li>link layer: MAC (sharing and power management), reliability </li></ul></ul><ul><ul><li>network layer: routing, mobility management </li></ul></ul><ul><ul><li>transport over wireless </li></ul></ul><ul><li>Mobile foundational services </li></ul><ul><ul><li>localization, security </li></ul></ul><ul><li>Application developments </li></ul><ul><ul><li>app. adaptation to handle mobility, portability </li></ul></ul><ul><ul><li>develop for heterogeneous devices </li></ul></ul>
    35. 35. Course Topics Transport Network Data Link Physical Communications Locations Location Management Localization Security Application Development
    36. 36. Class Materials <ul><li>Chapters of reference books </li></ul><ul><li>Selected conference and journal papers </li></ul><ul><li>Other resources </li></ul><ul><ul><li>MOBICOM, SIGCOMM, INFOCOM Proceedings </li></ul></ul><ul><ul><li>IEEE Network, Communications, Pervasive magazines </li></ul></ul>
    37. 37. Suggested Reference Books <ul><li>&quot;Mobile Communications, Second Edition,&quot; by Jochen Schiller, Addison Wesley. 2nd Ed. August 2003. </li></ul><ul><li>“ 802.11 Wireless Networks: the Definitive Guide” by Matthew Gast, O’Reilly, 2005 (available online) </li></ul>
    38. 38. Suggested Reference Books (2) <ul><li>“ Fundamentals of Wireless Communication”, by David Tse and Pramod Viswanath, Cambridge University Press, 2005. (available online) </li></ul><ul><li>&quot;Mobile Computing Handbook,&quot; by Mohammad Ilyas and Imad Mahgoub, CRC Press, 2005. </li></ul>
    39. 39. What You Need to Do <ul><li>Your prerequisite </li></ul><ul><ul><li>motivated, critical </li></ul></ul><ul><ul><li>basic programming skill </li></ul></ul><ul><li>Your workload </li></ul><ul><ul><li>class participation </li></ul></ul><ul><ul><ul><li>actively participate in class discussions </li></ul></ul></ul><ul><ul><li>assignments </li></ul></ul><ul><ul><li>class project </li></ul></ul><ul><ul><li>exam </li></ul></ul>
    40. 40. Class Project <ul><li>Goal: obtain hands-on experience </li></ul><ul><li>I’ll suggest potential topics </li></ul><ul><li>You may also choose your own topic </li></ul><ul><li>Initial proposal + midterm progress report + final report + [presentation] </li></ul><ul><li>We can provide Window Mobile/Google Andriod Dev Phone devices </li></ul>
    41. 41. Grading <ul><li>More important is what you realize/learn than the grades </li></ul>Project 35 % Assignments 35 % Exam 20% Class Participation 10 %
    42. 42. Class Survey <ul><li>Please take the class survey </li></ul><ul><ul><li>help me to determine your background </li></ul></ul><ul><ul><li>help me to determine the depth and topics </li></ul></ul><ul><ul><li>suggest topics that you want to be covered </li></ul></ul>
    43. 43. Questions?
    44. 44. Overview of Wireless Transmissions bit stream receiver source decoding channel decoding demodulation source coding bit stream channel coding analog signal sender modulation
    45. 45. Signal <ul><li>Signal are generated as physical representation s of data </li></ul><ul><li>A signal is a function of time and location </li></ul>t 1 0 t a special type of signal, s ine wave s, also called harmonics: s(t) = A t sin(2  f t t +  t ) with frequency f , period T=1/ f , amplitude A, phase shift  1 0 ideal digital signal t
    46. 46. Fundamental Question: Why Not Send Digital Signal in Wireless Communications? 1 0 ideal digital signal t
    47. 47. Fourier Transform: Every Signal Can be Decomposed as a Collection of Harmonics 1 0 1 0 t t ideal periodic al digital signal decomposition The more harmonics used, the smaller the approximation error.
    48. 48.
    49. 49. Fundamental Question: Why Not Send Digital Signal in Wireless Communications? <ul><li>May cause interference </li></ul><ul><ul><li>suppose digital frame length T, then signal decomposes into frequencies at 1/T, 2/T, 3/T, … </li></ul></ul><ul><ul><li>let T = 1 ms, generates radio waves at frequencies of 1 KHz, 2 KHz, 3 KHz, … </li></ul></ul>
    50. 50. Frequencies for C ommunications VLF = Very Low Frequency UHF = Ultra High Frequency LF = Low Frequency SHF = Super High Frequency MF = Medium Frequency EHF = Extra High Frequency HF = High Frequency UV = Ultraviolet Light VHF = Very High Frequency Frequency and wave length:  = c/f wave length  , speed of light c  3x10 8 m/s, frequency f 1 Mm 300 Hz 10 km 30 kHz 100 m 3 MHz 1 m 300 MHz 10 mm 30 GHz 100  m 3 THz 1  m 300 THz visible light VLF LF MF HF VHF UHF SHF EHF infrared UV optical transmission coax cable twisted pair
    51. 51. Frequencies and R egulations <ul><li>ITU-R holds auctions for new frequencies, manages frequency bands worldwide (WRC, World Radio Conferences) </li></ul>Europe USA Japan Cellular Phones GSM 450 - 457, 479 - 486/460 - 467,489 - 496, 890 - 915/935 - 960, 1710 - 1785/1805 - 1880 UMTS (FDD) 1920 - 1980, 2110 - 2190 UMTS (TDD) 1900 - 1920, 2020 - 2025 AMPS , TDMA , CDMA 824 - 849, 869 - 894 TDMA , CDMA , GSM 1850 - 1910, 1930 - 1990 PDC 810 - 826, 940 - 956, 1429 - 1465, 1477 - 1513 Cordless Phones CT1+ 885 - 887, 930 - 932 CT2 864 - 868 DECT 1880 - 1900 PACS 1850 - 1910, 1930 - 1990 PACS - UB 1910 - 1930 PHS 1895 - 1918 JCT 254 - 380 Wireless LANs IEEE 802.11 2400 - 2483 HIPERLAN 2 5150 - 5350, 5470 - 5725 902 - 928 I EEE 802.11 2400 - 2483 5150 - 5350, 5725 - 5825 IEEE 802.11 2471 - 2497 5150 - 5250 Others RF - Control 27, 128, 418, 433, 868 RF - Control 315, 915 RF - Control 426, 868
    52. 52. Spectrum and Bandwidth : Shannon Channel Capacity <ul><li>The maximum number of bits that can be transmitted per second by a physical channel is: </li></ul><ul><li>where W is the frequency range of the channel, and S/N is the signal noise ratio, assuming Gaussian noise </li></ul>
    53. 53. Modulation <ul><li>Objective </li></ul><ul><ul><li>encode digital data into analog signal s at the right frequency range with limited usage of spectrum </li></ul></ul><ul><li>Basic schemes </li></ul><ul><ul><li>Amplitude Modulation (AM) </li></ul></ul><ul><ul><li>Frequency Modulation (FM) </li></ul></ul><ul><ul><li>Phase Modulation (PM) </li></ul></ul>
    54. 54. M odulation <ul><li>Modulation of digital signals known as Shift Keying </li></ul><ul><li>Amplitude Shift Keying (ASK): </li></ul><ul><li>Frequency Shift Keying (FSK): </li></ul><ul><li>Phase Shift Keying (PSK): </li></ul>1 0 1 t 1 0 1 t 1 0 1 t
    55. 55. ATT and Verizon 3G Coverage http://mobileroar.com/wp-content/uploads/2008/07/3g-verizon.gif

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