Date post: | 31-Mar-2015 |
Category: |
Documents |
Upload: | lorena-keech |
View: | 214 times |
Download: | 1 times |
Mani SrivastavaUCLA - EE DepartmentRoom: 6731-H Boelter HallEmail: [email protected]: 310-267-2098WWW: http://www.ee.ucla.edu/~mbs
Copyright 2002 Mani Srivastava
Mobile & Wireless SystemsEE206A (Spring 2002): Lecture #1
Copyright 2002 Mani Srivastava2
Welcome to EE206A!
Course logistics
Course overview
Copyright 2002 Mani Srivastava3
Course Logistics: Instructor Info
Email: [email protected] Phone: 310-267-2098 Office: 6731-H BH Office hours: Th 12-2 PM, or by appointment
I’m very responsive with email Usually around on weekend
Assistant: Letty Marr, 7440D BH [email protected]
Copyright 2002 Mani Srivastava4
Course Logistics: Prerequisites and Status in Curriculum
No prerequisite graduate courses Knowledge of computer networking and digital
communications at advanced undergraduate level Embedded Computing Systems elective Prelim question in Communications Related courses
Estrin’s CS213 (Distributed Embedded Systems)
Copyright 2002 Mani Srivastava5
Course Logistics: Grading One take-home examination: 17.5%
9th or 10th week of classes Homeworks: 17.5%
problem solving, analysis, theoretical, simulation Class presentation: 15%
one topic per group from a specified set 30 minute presentation
Project: 25% results, 10% report, 5% presentation groups of 1-3 students 30 minute presentation during final week like a conference paper and talk
Class participation: 10% E.g. question you ask and how much you interact
Copyright 2002 Mani Srivastava6
Course Logistics: Enrollment
Limit of 30 students Wait till end of week 2 as many students drop out If you want to audit, following is the priority
You are on the official wait list You contacted me - unofficial “wait list to get on to
wait list”
If you are not serious about the course, pleasedrop out soon so that those is the waiting list can
enroll!
Copyright 2002 Mani Srivastava7
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!
Copyright 2002 Mani Srivastava8
Course Logistics: On the Web
Course web site URLhttp://www.ee.ucla.edu/~mbs/courses/ee206a/2002s
On-line material lecture viewgraphs in PDF & PPT
check before class, and print them viewgraphs are organized topic-wise and would span several classes
copies of handouts, home works, exams etc. important announcements on-line reader with pointers to URLs, Melvyl
Class mailing list [email protected] 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
Copyright 2002 Mani Srivastava9
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
Copyright 2002 Mani Srivastava10
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)
Copyright 2002 Mani Srivastava11
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;
Copyright 2002 Mani Srivastava12
Course Logistics: Conferences and Journals
Conferences & Workshops Main: MOBICOM, MOBIHOC, INFOCOM Others: SIGCOM, MoMuC, ICUPC, PIMRC,
WoWMoM, ICC, Globecom, etc.
Journals & Magazines Main: ACM/Baltzer WINET, ACM/Baltzer MONET,
IEEE Personal Communications Others: IEEE Trans of N/W, JSAC etc.
Copyright 2002 Mani Srivastava13
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!
Copyright 2002 Mani Srivastava14
Copyright 2002 Mani Srivastava15
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 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
Copyright 2002 Mani Srivastava16
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
Copyright 2002 Mani Srivastava17
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
Copyright 2002 Mani Srivastava18
WWW + Mobile Telephony = Mobile Access to Information
0
100
200
300
400
500
600
1993 1994 1995 1996 1997 1998 1999 2000 2001
Mobile TelephoneUsers
Internet Users
Copyright 2002 Mani Srivastava19
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
Copyright 2002 Mani Srivastava20
Novel Wireless Terminals
Qubit’s Orbit WebpadKyocera QCP 6035
Smartphone with Palm Handspring Treo
Danger’s Hiptop iPaq with Bluetooth
Copyright 2002 Mani Srivastava21
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
Copyright 2002 Mani Srivastava25
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
Copyright 2002 Mani Srivastava26
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)
Copyright 2002 Mani Srivastava27
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 & higher) HomeRF
Personal area Networks Bluetooth, 802.15
Wireless device networks Sensor networks, wirelessly networked robots
Copyright 2002 Mani Srivastava28
Example: Sensor-Enhanced Gadgets
SmartQuill (by British Telecom)• http://www.innovate.bt.com/showcase/smartquill/index.htm• ADXL 202 monitors movement using ‘spatial sensing’• Password by signature recognition
ADXL202• Dual Axis, ±2g• 2.7V-5.25V Single Supply• 1000g Shock Survival• $40
Copyright 2002 Mani Srivastava29
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
Copyright 2002 Mani Srivastava30
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
Copyright 2002 Mani Srivastava31
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
Copyright 2002 Mani Srivastava32
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
Copyright 2002 Mani Srivastava33
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
MoreSignalProcessing
Copyright 2002 Mani Srivastava34
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
MoreProtocolProcessing
Copyright 2002 Mani Srivastava35
Novel Attributes of Mobile and Wireless Systems
Wireless Mobility Portability
limited battery capacity limited computing limited storage small dimensions risk to data (easily lost)
MoreEnergyEfficiency
Copyright 2002 Mani Srivastava36
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
Copyright 2002 Mani Srivastava37
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
Copyright 2002 Mani Srivastava38
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
Copyright 2002 Mani Srivastava39
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
Copyright 2002 Mani Srivastava40
Heterogeneous Networks
Seamless mobility across diverse overlay networks “vertical” hand-offs software “agents” for heterogeneity management IP as the common denominator?
High-tier
Low-tier
Satellite
High Mobility Low MobilityWide Area
Regional Area
Local Area
Copyright 2002 Mani Srivastava41
Ad Hoc Networks
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.
• Disaster recovery
• Battlefield
• ‘Smart’ office
• Etc.
Copyright 2002 Mani Srivastava42
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?
Copyright 2002 Mani Srivastava43
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?
Copyright 2002 Mani Srivastava44
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
Copyright 2002 Mani Srivastava45
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
Copyright 2002 Mani Srivastava46
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
Copyright 2002 Mani Srivastava47
Battery Technology
Battery technology has historically improved at a very slow pace
NiCd improved by x2 over 30 years! require breakthroughs in chemistry
Battery Rechargeable? Gravimetric Density(Wh/lb)
Volumetric Density(Wh/l)
Alkaline-MnO2(typical AA)
NO 65.8 347
Silver oxide NO 60 500Li/MnO2 NO 105 550Zinc Air NO 140 1150NiCd YES 23 125Li-Polymer YES 65-90 300-415
Copyright 2002 Mani Srivastava48
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
Copyright 2002 Mani Srivastava49
Key Issue: Resource AwarenessAd-hoc architecture Self-configuration
Wireless communications Variability
Inherent unpredictability
Solution: adaptation
Select required performance level Operate always at peak performance
Settings based on external conditions
Fixed settings set by worst case conditions
Resource awareness“right resource at the right time and the right place”
Wireless Backbone Networks High traffic load Limited available spectrum
Focus on transmission resources
Wireless Ad-Hoc Networks Unattended operation Limited available battery
Focus on energy resources
Copyright 2002 Mani Srivastava50
Generic Mobile and Wireless System Architecture
Application & Services
OS & Middleware
Network
Data Link
Radio, IR
PartitioningSource coding, DSPContext adaptation
Disconnection managementPower managementQoS management
ReroutingImpact on TCPLocation tracking
Multiple accessLink error controlChannel allocation
Wireless channel modelsChannel codingRF circuits, Radio modemsAntennas
Thi
s C
ours
eC
ross-layer Optim
izations
Copyright 2002 Mani Srivastava51
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.
Copyright 2002 Mani Srivastava52
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
Copyright 2002 Mani Srivastava53
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 READINGNone.