20-751 ECOMMERCE TECHNOLOGY FALL 2003 COPYRIGHT © 2003 MICHAEL I. SHAMOS Wireless Technologies.

20-751 ECOMMERCE TECHNOLOGY

FALL 2003

Wireless Technologies

FALL 2003

Outline

• Wireless technology overview• Cellular communications• Satellite systems• Wireless LAN

– 802.11, Bluetooth, UWB

• Mobility support– WAP

• Wireless applications

FALL 2003

Why Wireless?

• Human freedom– Portability v. Mobility

• Objective: “anything, anytime, anywhere”• Mobility

– Size, weight, power– Functionality– Content

• Infrastructure required• Cost

– Capital, operational

FALL 2003

Worldwide Mobile Subscribers

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

1,600,000

1,800,000

2000 2001 2002 2003 2004 2005

Asia Pacific

Latin America

Western Europe

North America

SOURCE: CTIA, iGillottResearch, 2001

FALL 2003

Electromagnetic Spectrum

SOURCE: JSC.MIL

SOUND LIGHTRADIO HARMFUL RADIATION

VHF = VERY HIGH FREQUENCYUHF = ULTRA HIGH FREQUENCYSHF = SUPER HIGH FREQUENCY EHF = EXTRA HIGH FREQUENCY

4G CELLULAR56-100 GHz

3G CELLULAR1.5-5.2 GHz

1G, 2G CELLULAR0.4-1.5GHz

3.1-10.6 GHz

FALL 2003

MOBILE

MARITIME MOBILE

BROADCAST

RADIOLOCATION

FALL 2003

Wireless Telephony

SOURCE: IEC.ORG

AIR LINK

PUBLIC SWITCHEDTELEPHONE NETWORK

FALL 2003

Cell Clusters

SOURCE: IEC.ORG

ACTUAL COVERAGEAREA OF CELL 1

ACTUAL COVERAGEAREA OF CELL 3

CELL 1 OVERLAPS 6 OTHERS

DIFFERENT FREQUENCIESMUST BE USED IN ADJACENTCELLS

SEVEN DIFFERENT SETS OFFREQUENCIES REQUIRED

FALL 2003

Space Division Multiple Access (SDMA)

PATTERN CAN BEREPLICATED OVERTHE ENTIRE EARTH

200 FREQUENCIESIN ONE CELL

TOTAL NUM BER OFFREQUENCIES = 1400

WORLDWIDE

MANY CELLS CAN SHARESAME FREQUENCIES IFSEPARATED IN SPACE

FALL 2003

Cell Handover

SOURCE: R. C. LEVINE, SMU

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 performancecontour

Handover thresholdcontour

A Bx y

ANIMATION

FALL 2003

Cell Sizes

MACROCELL: $1M

MICROCELL: $250K

SLOW-MOVINGSUBSCRIBERS

FAST-MOVINGSUBSCRIBERS

PICOCELLS

GSM: 100m - 50 km 250 km/hr

FALL 2003

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”

FALL 2003

Frequency Division Multiplexing (FDMA)

Advantages:• No dynamic coordination

Disadvantages:• Inflexible & inefficient if

channel load is dynamic and uneven

k2 k3 k4 k5 k6k1

Each channel gets a band (range) of frequenciesUsed in traditional radio, TV, 1G cellular

EACH CHANNELOCCUPIES SAME

FREQUENCYAT ALL TIMES

SOURCE: NORMAN SADEH

FALL 2003

k2 k3 k4 k5 k6k1

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 consumptionDisadvantage: Requires precise synchronization

c FREQUENCY BAND

FALL 2003

Combining TDMA and FDMA

k2 k3 k4 k5 k6k1

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

FALL 2003

Time-Division Multiple Access

SOURCE: QUALCOMM

FALL 2003

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 synchronization

between different channels– resists interference and tapping– 3X capacity of TDMA, 1/25 power consumption

• Disadvantages:– more complex signal regeneration

• Implemented using spread spectrum

k2 k3 k4 k5 k6k1

FALL 2003

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”

FALL 2003

GSM Architecture

SOURCE: UWC

LIST OFROAMINGVISITORS

LIST OF SUBSCRIBERSIN THIS AREA

STOLEN, BROKENCELLPHONE LIST

ENCRYPTION,AUTHENTICATION

INTERFACE TO LANDTELEPHONE NETWORKS

HIERARCHYOF CELLS

CELL TRANSMITTER& RECEIVER

SIM:IDENTIFIES ASUBSCRIBER

DATA RATE: 9.6 Kbps

FALL 2003

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

Technology Message Length

2 way?

GSM 160 bytes Yes

TDMA/PDC 160 bytes No

CDMA 256 bytes Yes

iDEN 140 bytes Yes

SOURCE: GEMBROOK SYSTEMS

FALL 2003

SMS in Banking

Credit card used

Joe’s HiFi$1245

BankBack-endSystems

Internet

Bank Web Site

Message from YourBank: Credit card

purchase of $1245 at Joe’s HiFi.

Message appears within seconds

on the customer’s phone

SMS Monitorin

g Application

Customer

Alert me to all credit

card transactions greater than

Cell Tower

WirelessCarrier

SMS Carrier

SOURCE: GEMBROOK SYSTEMS

FALL 2003

Satellite Systems

SOURCE: WASHINGTON UNIV.

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

FALL 2003

Geostationary Orbit

SOURCE: BILL LUTHER, FCC

FALL 2003

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

FALL 2003

GPS Trilateration

DISTANCE MEASUREMENTSMUST BE VERY PRECISE

LIGHT TRAVELS 1018 FEETEACH MICROSECOND

SOURCE: PETER DANA

FALL 2003

Automatic Vehicle Location (AVL)

SOURCE: TRIMBLE NAVIGATION

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 demoCA

FALL 2003

Location-Aware Applications

• Vehicle tracking• Firemen in buildings, vital signs, oxygen remaining• Asset tracking• Baggage• Shoppers assistance• Robots• Corporate visitors• Insurance• Barges

FALL 2003

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

FALL 2003

Wireless LAN Components

SOURCE: LUCENT

WavePOINT IITransmitter

ExtendedRange

Antenna

EthernetConverter

11 Mbps WaveLANPCMCIA Card

WaveLAN ISA(Industry StandardArchitecture) Card

FALL 2003

Wireless LAN Configurations

SOURCE: PROXIM.COM

WIRELESS PEER-TO-PEERCLIENT AND ACCESS POINT

MULTIPLE ACCESS POINTS + ROAMING

BRIDGING WITHDIRECTIONAL ANTENNAS

UP TO 17 KM !

FALL 2003

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

FALL 2003

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.

FALL 2003

Bluetooth Devices

NOKIA 9110 + FUJIDIGITAL CAMERA

ERICSSONCOMMUNICATOR

ERICSSON R520GSM 900/1800/1900

ALCATELOne TouchTM 700

GPRS, WAPERICSSON

BLUETOOTHCELLPHONE

HEADSET

FALL 2003

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

FALL 2003

Bluetooth Scatternets

Master

Piconet

ScatterNet

Master / Slave

Scatternet Piconets

SOURCE: KRISHNA BHOUTIKA

FALL 2003

Time-Modulated Ultra-Wideband (TM-UWB)

• Not a sinewave, but millions of pulses per second

• Time coded to make noise-likesignal

• Pulse position modulation

500 ps

Randomized Time Coding

“0” “1” Pow

Frequency (GHz)1 2 3 4 5

Frequency (GHz)

Random noise signal

SOURCE: TIME DOMAIN

Spread Spectrum

FALL 2003

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

PulsON, A Chip Based Solution

FALL 2003

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

FALL 2003

WAP Applications

Web ContentServer

MobileTerminal

MobileNetwork

Internet

WAP Gateway

Non Mobile Internet User

DatabaseServer

SOURCE: DANETWAP simulator

iNexware

FALL 2003

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:

SOURCE: EUROTECHNOLOGY JAPAN K.K.

iMode FAQ

FALL 2003

• 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 amount

of data transmitted

SOURCES: XML.COM, EUROTECHNOLOGY.COM

FALL 2003

• 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

FALL 2003

iMode Operation

DoCoMoDoCoMoPacketPacket

Network Network (PDC-P)(PDC-P)IP

INFOPROVIDER

INTERNET

iMode Servers

BILLINGDB

USERDB

PACKET DATAHTTP

SOURCE: SAITO & SHIN

FALL 2003

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 )

• 4G 2010? (10 Mbs? )

• UWB potential to deliver 500 Mbps over short distances

SOURCE: JOHN DOWNARD

FALL 2003

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

FALL 2003

Code Division

SOURCE: JOCHEN SCHILLER

1 10DATA

1 1 1 1 1 1 1 10 0 0 0 0 00000“CODE”

0 0 0 0 0 0 0 0 0 011 1 1 1111DATA CODE

ACTUALSIGNAL

FALL 2003

Code Division

1 00DATA B

0 1 1 0 0 1 1 10 1 0 0 0 10100“CODE” B

1 0 0 1 0 0 0 1 1 111 0 0 1011DATA CODE

ACTUALSIGNAL

FALL 2003

Two CDMA Signals

ACTUALSIGNAL

FALL 2003

Recovering Data A From A+B

ACTUALSIGNAL

1 1 1 1 1 1 1 10 0 0 0 0 00000“CODE” A

-(A+B) *CODE A

INTEGRAL1

20-751 ECOMMERCE TECHNOLOGY FALL 2003 COPYRIGHT © 2003 MICHAEL I. SHAMOS Wireless Technologies.

ecommerce technology

space slide

shamos cell handover

operational slide

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kmhr slide

shamos cell clusters

frequencies cell

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