Mani Srivastava UCLA - EE Department Room: 6731-H Boelter Hall Email: [email protected] Tel: 310-267-2098 WWW: mbs Copyright 2002

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


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]


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)


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


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!


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!


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


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


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)


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;


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.


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!



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


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


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


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


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


Novel Wireless Terminals

Qubit’s Orbit WebpadKyocera QCP 6035

Smartphone with Palm Handspring Treo

Danger’s Hiptop iPaq with Bluetooth


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


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


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)


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


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


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


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


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


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


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



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



Wireless Mobility Portability

limited battery capacity limited computing limited storage small dimensions risk to data (easily lost)

MoreEnergyEfficiency


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


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


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


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


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


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.


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?


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?


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


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


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


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


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


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


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


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.


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


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.

Documents

Mani Srivastava UCLA - EE Department Room: 6731-H Boelter Hall Email: [email protected] Tel: 310-267-2098 WWW: mbs Copyright 2002