Mobile & Wireless Systems

1. Mobile & Wireless Systems EE206A (Spring 2001): Lecture #1

2. Welcome to EE206A! • Course logistics • Course overview

3. Course Logistics: Instructor Info • Email: mbs@ee.ucla.edu • Phone: 310-267-2098 • Office: 7702-B BH • Office hours: Th 3-5 PM, or by appointment • Assistant: Letty Marr, 7440D BH letty@ea.ucla.edu

4. Course Logistics: Prerequisites • No formal prerequisite • Knowledge of computer networking and digital communications at advanced undergraduate level • Embedded Computing Systems elective

5. Course Logistics: Grading • One take-home examination: 20% • 9th or 10th week of classes • Two home works: 15% • problem solving, analysis, theoretical, simulation • One presentation: 15% • one topic per student from a specified set • 20-30 minute presentation • Class project: 25% results, 10% report, 5% presentation • groups of up to two students • 30 minute presentation during final week • like a conference paper and talk • Class participation: 10%

6. Course Logistics: Project • Dig deep into a focus area on your own • lectures would provide a “broad” coverage • Should have some new idea/result, even if minor • one or more of simulation, analysis, implementation • no paper reviews and surveys • Project proposal due by beginning of week 3 • project web page will have suggested project topics • may relate to your own research • but you cannot “reuse” work already done or being done for some other purpose • What should be your goal? • something useful • similar quality as a conference paper and talk • key is to keep the project simple, and focused • aim high – past projects have led to papers top conferences!

7. Course Logistics: On the Web • Course web site URL http://www.ee.ucla.edu/~mbs/courses/ee206a/2001s • On-line material • lecture viewgraphs in PDF & PPT • check before class, and print them • copies of handouts, home works, exams etc. • important announcements • on-line reader with pointers to URLs, Melvyl • Class mailing list • ee206a-l@ucla.edu • make sure to write your name on the sign-up sheet • If auditing, please let me know if you wish to be on the list

8. Course Logistics: Reader & Textbooks • No books are required. • A set of papers will be required reading • average of 1-2 paper per lecture • will relate to the core topic of that lecture • you should read them before the lecture • In addition, every student will present a talk • cover alternate ideas or related topics • lead discussion but every one is supposed to participate • selected from a set of topics of my choosing • I will give pointers to papers and web resources

9. Course Logistics: Reader & Textbooks (contd.) • No paper reader - an “on-line reader” is being maintained at the course web site • bibliographic entries for various papers • links to on-line versions if available • or, indication whether available through Melvyl’s INSPEC database • hardcopies will be handed out for papers not available on-line • Typically access on-line papers from Melvyl (http://www.melvyl.ucop.edu)

10. Course Logistics: Some Books (for your interest only…) • Wireless Communications : Principles And Practice; Rappaport, Theodore S. Prince Hall Publishing; 09/1995; • Mobility: Processes, Computers, and Agents; Milojicic, D. S./ Douglis, F./ Wheeler, R.G.; Addison-Wesley, 04/1999. • Mobile Computing (Kluwer International Series in Engineering and Computer Science, No 353); Imielinski, Tomasz (Edt)/ Korth, Henry F. (Edt). Kluwer Academic Pub; 1/96; • Mobile IP : Design Principles And Practices; Perkins, Charles / Woolf, Bobby. Addison Wesley; 11/1997; • Wireless Multimedia Communications : Networking Video, Voice and Data; Wesel, Ellen Kayata. Addison Wesley; 12/1997; • Wireless Personal Communications; A Systems Approach; Goodman, David J. Addison Wesley; 09/1997;Principles of Mobile Communication; Stuber, Gordon L. Kluwer Academic Publishing; 6/96; • Second Generation Mobile And Wireless Technologies; Black, Uyless Prentice Hall; 09/1998;

11. Course Logistics: Conferences and Journals • Conferences & Workshops • Main: MOBICOM • Others: SIGCOM, INFOCOM, MoMuC, ICUPC, PIMRC, WoWMoM, ICC, Globecom, Mobihoc, etc. • Journals & Magazines • Main: ACM/Baltzer WINET, ACM/Baltzer MONET, IEEE Personal Communications • Others: IEEE Trans of N/W, JSAC etc.

12. Makeup for Missed Lectures • I will have to miss following lectures • (probably) April 19 due to DARPA PAC/C PI meeting • (definitely) April 24 due to Infocom • Possibly one in May • Will propose make-up slot

13. Cheating & Plagiarism • My apologies if you are one of the vast majority of students who don’t resort to academic dishonesty • but unfortunate incidents in my previous grad and undergrad courses • What is cheating & plagiarism? • Acting dishonestly, practicing fraud • Stealing or using (without my permission) other people’s writings or ideas • E.g. from other students, other sources such as web sites, solutions from previous offerings of this course etc. • Note that it doesn’t have to be literal copying – stealing ideas but presenting in a different style is still cheating and plagiarism. • You are also guilty if you aid in cheating & plagiarism • My policy: zero tolerance • HWs, paper presentation: zero score + one level reduction in course grade • Exam, project: “F” grade for the course + report to Dean • More than 1 incident: : “F” grade for the course + report to Dean • Moreover, please remember that you may have to face me in other exams (e.g. prelims, qualifiers) and professionally!

15. Growth in Wireless Systems • Rapid growth in cellular/PCS voice services over the last decade • Cell phones everywhere! • Wireless data still a small market, but a fast growing one with lots of exciting action • WLAN rapidly growing • 802.11b, 802.11a, Bluetooth, Home-RF • Wide area wireless data also growing • Ricochet’s 128 kbps IP service • support for data in 2.5G and 3G wireless • Wireless broadband • Location-based services, WAP

16. Why is Wireless Data Still a Small Market? • Lack of killer application • Unsuitable terminal devices • Lack of standard air interfaces and services • Lack of universal coverage • Poor performance of wireless WANs • due to low bit rates, high latencies, and high error rates of existing wide-area wireless air interfaces • But, technology trends augur well... • However, business factors • high pricing and cost: offering voice service more lucrative • spectrum shortage

17. Favorable Technology Trends • Availability of a pervasive data network (Internet) • Innovative Internet-based applications and services particularly useful to mobile users • personalized information retrieval, access to airline reservations systems, online trading • Novel terminal devices • compact size, low power, ease of use • next generation will have built-in wireless interfaces • Emerging wide-area wireless packet data services • aggregate data rates of several 100 kbps • TCP/IP-friendly link layer protocols

18. WWW + Mobile Telephony = Mobile Access to Information Mobile Telephone Users Internet Users

19. Evolution in Information Systems • Wired  wireless, e.g. wired phones  cellular • more freedom of location and time • Voice telephony, data  multimedia • Intelligent telecom n/w  networked computing • intelligence at the edges of the network • programmable servers intermixed with switching infrastructure for rapid service deployment • Networked computing is becoming pervasive • personal  networked  mobile  pervasive • more flexible resource usage, more freedom of location and time, more efficient flow of information • Moving beyond phones and PCs • embedded devices & sensor-based smart spaces

20. Novel Wireless Terminals Qubit’s Orbit Webpad Kyocera QCP 6035Smartphone with Palm Handspring Visorphone

21. Network Infrastructure • Dynamic, programmatic creation/composition of scalable, highly available & customizable services • automatic adaptation to end device characteristics and network connectivity • dynamic composition of component services • Diverse appliances beyond the phone and the PC • devices plus servers in the infrastructure • Arbitrarily powerful services on arbitrarily small clients using an adaptive infrastructure • computing resources mixed with switching fabric • WAP: wireless application protocol

22. What is this course about? • Mobile and wireless networked computing and communication systems • Emphasis on emerging systems • beyond traditional cellular telephone systems • wireless packet-switched data and multimedia • beyond network of phones and PCs • networks of large # of wireless embedded systems • Emphasis on interaction between layers of the system • not about radio design or communication theory • link/network/transport, application, OS/middleware • optimizations across layers

23. Evolution of Mobile and RF Wireless Systems • 1st generation: analog - voice • AMPS with manual roaming • cordless phones • packet radio • 2nd generation: digital - voice, data • cellular & PCS with seamless roaming and integrated paging (IS-95, IS-136, GSM) • multizone digital cordless • wireless LANs (802.11), MANs (Metricom), and WANs (CDPD, Ardis, RAM, Mobitext)

24. Beyond the 2nd Generation • Wide-area mobile voice/data • 2.5G: GPRS • 3G standards: UMTS,/IMT2000, wideband CDMA, CDMA2000, EDGE • Fixed Point-to-multipoint broadband wireless access 802.16 • LMDS (local multipoint distribution) 24-28GHz • MMDS below 5 GHz • Free space optics (Terabeam) • Higher-speed WLAN • 802.11b (2.4GHz, 11 Mbps), 802.11a (5GHz, 54 Mbps) • HomeRF • Personal area Networks • Bluetooth, 802.15 • Wireless device networks • Sensor networks, wirelessly networked robots

25. Example: Sensor-Enhanced Gadgets • ADXL202 • Dual Axis, ±2g • 2.7V-5.25V Single Supply • 1000g Shock Survival • $40 • SmartQuill (by British Telecom) • http://www.innovate.bt.com/showcase/smartquill/index.htm • ADXL 202 monitors movement using ‘spatial sensing’ • Password by signature recognition

26. Example: MIT’s “Expressive Footwear” • Dance shoes with wireless link & a suite of sensors • measure dynamic parameters at a dancer's foot • differential pressure at 3 points and bend in the sole, 2-axis tilt, 3-axis shock, height off the stage, orientation, angular rate and translational position) • example use: generate accompanying music

27. Telecom View of theFuture Information Systems 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 - anytime, anywhere, in a timely, cost-effective way. George Heilmeier (CEO of Bellcore)IEEE Communication Magazine, 1992

28. Computing View of theFuture Information Systems The most profound technologies are those that disappear. They weave themselves into the fabric of everyday life until they are indistinguishable from it... the idea of a “personal computer” itself is misplaced... the vision of laptop machines, dynabooks and “knowledge navigators” is only a transitional step... a new way of thinking about computers, one that takes into account the human world and allows the computers themselves to vanish into the background. Mark Weiser (Chief Technologist, Xerox PARC)Scientific American, September1991

29. Alternate Models of Mobile Computing Systems • Ubiquitous Information Access • information distributed everywhere by the “net” • terminal centric • users carry wireless terminals • terminal is the universal service access device • terminal adapts to location and services • Ubiquitous Computing • cheap computers of different scales and types embedded everywhere • 100s of computer in every room in the form of common, day-to-day objects • user centric • computers swapped among users • computers dedicated to service • computers adapt to location and users

30. Novel Attributes of Mobile and Wireless Systems • Wireless • limited bandwidth • high latency • < 3 ms indoor • > 100 ms outdoor (cellular, satellite) • variable link quality • noise, disconnections, interference • link asymmetry • heterogeneous air interfaces • easier snooping • Mobility • Portability More Signal Processing

31. Novel Attributes of Mobile and Wireless Systems • Wireless • Mobility • user and terminal location • are system variables of interest • change dynamically • speed of terminal mobility impactswireless bandwidth • constants become variable • location, environment, connectivity, b/w,I/O devices, security domain • easier spoofing • Portability More Protocol Processing

32. Novel Attributes of Mobile and Wireless Systems • Wireless • Mobility • Portability • limited battery capacity • limited computing • limited storage • small dimensions • risk to data (easily lost) More Energy Efficiency

33. Disconnections • Planned vs. unplanned • Choices? • engineer to prevent disconnections • gracefully cope (adapt) to disconnections • Mask disconnections and round-trip latencies • decouple communication from data production/consumption • asynchronous operation (multiple REQs before ACKs), prefetching, delayed write-back etc. • Tolerate by autonomous operation, caching/hoarding, local applications etc. • disconnected filesystems, e.g. CMU’s CODA • Good user interfaces to give feedback about disconnection

34. Limited Bandwidth • Difference between indoor (1-10Mbps) and outdoor (10s of Kbps) • mobility, multipath • Right metric? • bps vs. bps per user vs. bps per unit volume • Cope by improving bandwidth usage • compression, buffering • techniques for disconnection (caching, delayed write-back) help • Schedule link bandwidth to improve user satisfaction • differentiate data according to quality of service • fair allocation of bandwidth

35. Bandwidth Variability • Variations due to change of network • ethernet vs. wavelan vs. CDPD • Variations due to changing wireless link condition • fading • How can applications cope? • operate only when all bandwidth available • design for worst case minimum bandwidth • adapt to available bandwidth • appropriate scheduling of packets on the link

36. Time Varying Wireless Environment • Wired networks • problem is congestion… need to share resources • resource reservation + scheduling can provide QoS • Wireless networks • sharing is only part of the problem • available wireless link resource undergoes dramatic and rapid changes • multipath reflection, doppler fading, frequency collisions • rapid signal fades and distortions as a receiver moves • necessitates aggressive signal processing and adaptive protocols

37. Satellite Regional Area Low-tier High-tier Local Area Wide Area Low Mobility High Mobility Heterogeneous Networks • Seamless mobility across diverse overlay networks • “vertical” hand-offs • software “agents” for heterogeneity management • IP as the common denominator?

38. Ad Hoc Networks • Disaster recovery • Battlefield • ‘Smart’ office • Etc. • Rapidly deployable infrastructure • Wireless: cabling impractical • Ad-Hoc: no advance planning • Backbone network: wireless IP routers • Network of access devices • Wireless: untethered • Ad-hoc: random deployment • Edge network: Sensor networks, Personal Area Networks (PANs), etc.

39. Address Migration due to Mobility • Dynamically changing network access point • In current internet (and PSTN) address corresponds to the point of attachment to n/w • applications/calls connect to a fixed address • active connections cannot be moved to new address • How to support changing network access point? • How to find the current address? • How to do rerouting? • How to do route optimization? • How to do multicast?

40. Rethinking Naming and Addresses in Wireless Systems • Conventional networks • Destination has a name represented by an id • Name maps to an address represented by an id • Routing done by id-based address • Large ad hoc networks, e.g. sensor networks • Hard to name by an id • Attribute based naming (“a sensor in the SW corner”) • Map attributes to id, and then route using id • or, perhaps route using the attributes? • how about no addresses? • get address for each transaction • Dynamically chosen addresses according to local density?

41. Location-dependent Information • Location affects configuration parameters • DNS, timezone, printer etc. • Location affects answer to user queries • e.g. where is the nearest printer • More complex location-dependent queries • e.g. where is the nearest taxi • Privacy concerns due to location tracking • Changing context • small movements may cause large changes • caching may become ineffective • dynamic transfer to nearest server for a service • Localization

42. Portability • Power is key • long mean-time-to-recharge, small weight, volume • Risk to data due to easier privacy breach • network integrated terminals with no local storage • Small user interfaces • small displays, analog inputs (speech, handwriting) instead of buttons and keyboards • Small storage capacity • data compression, network storage, compressed virtual memory, compact scripts vs. compiled code

43. Low Power & Energy-awareness • Battery technology is a hurdle… no Moore’s Law to help out • Typical laptop: 30% display, 30% CPU, 30% rest • wireless communication and multimedia processing incur significant power overhead • Low power • circuits, architectures, protocols • Power management • Right power at the right place at the right time • Battery model

44. Battery Technology • Battery technology has historically improved at a very slow pace • NiCd improved by x2 over 30 years! • require breakthroughs in chemistry

45. Summary: Challenges in Mobile and Wireless Computing • Portable, energy-efficient devices • End-to-end quality of service • Seamless operation under context changes • Context-aware operation • Secure operation • Sophisticated services for simple clients

46. Key Issue: Resource Awareness Inherent unpredictability Wireless Backbone Networks • High traffic load • Limited available spectrum Focus on transmission resources Solution: adaptation Resource awareness “right resource at the right time and the right place” • Wireless Ad-Hoc Networks • Unattended operation • Limited available battery • Focus on energy resources

47. Application & Services OS & Middleware Network Data Link Radio, IR Generic Mobile and Wireless System Architecture Partitioning Source coding, DSP Context adaptation Disconnection managementPower managementQoS management This Course ReroutingImpact on TCPLocation tracking Cross-layer Optimizations Multiple accessLink error controlChannel allocation Wireless channel models Channel coding RF circuits, Radio modems Antennas

48. Goal for This Course Explain the impact of Mobility, Wireless, and Energy Efficiency on Link, Network, OS, and Application Layers in End-point, Network Infrastructure, and Services for Networked Wireless/Mobile Embedded Systems.

49. Course Plan: Topics • Physical layer concepts (radio propagation, wireless channel, antennas, novel forms of wireless comm) • Link layer protocols, medium access, adaptivity, packet scheduling • Mobile-IP, ad hoc routing, wireless TCP, QoS in mobile networks • Sensor network protocols and algorithms • Low power and power management • OS, middleware, and application issues • Other emerging topics as time permits

50. Reading List for This Lecture • MANDATORY READING [Weiser91] M. Weiser, "The Computer for the 21st Century," Scientific American, vol. 265, no. 3, pp. 94-104, September 1991.(draft copy at http://www.ubiq.com/hypertext/weiser/SciAmDraft3.html) • RECOMMENDED READING None.