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Is Wireless (Data) Dead?Is Wireless (Data) Dead?
Randy H. KatzRandy H. KatzComputer Science Division, EECS DepartmentComputer Science Division, EECS Department
University of California, Berkeley, CA 94720-1776University of California, Berkeley, CA 94720-1776© 1997© 1997
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Heilmeier’s VisionHeilmeier’s Vision
•• AccessAccess–– Internet connectivityInternet connectivity
•• Anytime, AnywhereAnytime, Anywhere–– Wide-Area CoverageWide-Area Coverage–– Scalable ProcessingScalable Processing–– Highly Available OperationHighly Available Operation
•• EasilyEasily–– Transparent AccessTransparent Access–– Localized ServiceLocalized Service
•• SecurelySecurely–– Global AuthenticationGlobal Authentication
•• Any MediumAny Medium–– Multimedia: AV/GraphicsMultimedia: AV/Graphics
•• TimelyTimely–– PerformancePerformance
•• Cost EffectiveCost Effective–– Heterogeneous Support via Heterogeneous Support via
ProxiesProxies
“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.” G. Heilmeier, 1992
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Marconi’s VisionMarconi’s Vision
“It is dangerous to put “It is dangerous to put limits on wireless.”limits on wireless.”
Guglielmo Marconi (1932)Guglielmo Marconi (1932)
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Presentation OutlinePresentation Outline
•• Wireless Definitions and TrendsWireless Definitions and Trends
•• Wireless TelephonyWireless Telephony
•• Quo Vadis Wireless Data?Quo Vadis Wireless Data?
•• Access is the Killer App!Access is the Killer App!
•• Summary and ConclusionsSummary and Conclusions
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The Wireless UniverseThe Wireless UniverseWireless Communications
Amateur Industrial Consumer Business Military/Aero Long-Haul
Automotive Monitoring
— IVHS— GPS
— AMR— Control
ResidentialCordless
Cellular Paging WPABX PMR/SMR Mobile Data
Analog Digital— CT-0— CT-1— CT-300
— DECT— CT-2— PHP— USCT— ISM
WLAN
Analog Digital— AMPS— ETACS— NMT450— NMT900— NMT-O— Comvik— JTACS
— GSM— IS-54— IS-95— RCR-27
— ARDIS— Mobitex— Omnitracs— Cellular/CDPD
— DECT— CT-2— PHP— USCT— ISM
— 802.11— DECT— HiPerLAN— ISM
— POSCAG— ERMES— SSB
PCN/PCS
— DCS1800— PHP— US??— LEO
— FPLMTS— UMTS— RACE— Others
Conv
ESMR— MIRS— TETRA
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Radio BasicsRadio BasicsWavelength (m)
104 102 100 10-2 10-4 10-6 10-8 10-10 10-12 10-14 10-16
104 106 108 1010 1012 1014 1016 1018 1020 1022 1024
Frequency (Hz)
RadioSpectrum
IR X-Ray CosmicRays
UV
Visible LightR O Y G B I V
< 30 KHz30 - 300 KHz300 KHz - 3 MHz3 - 30 MHz30 - 300 MHz300 MHz - 3 GHz3 - 30 GHz> 30 GHz
VLFLFMFHFVHFUHFSHFEHF
Speed of Light = λ * ƒ = 3 x 108
AM RadioFM Radio, TV
Cell PhoneSatellite
1 MHz100 MHz
1 GHz10 GHz
300 m3 m
30 cm3 cm
≈1000 ft≈10 ft≈1 ft≈1 in
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Absorption
Ionosphere
Reflected
HF Transmission
Line of Sight
Directional Antenna
VHF Transmission
Reflected waveinterferes with signal
Radio BasicsRadio Basics
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Wireless SpectrumWireless Spectrum
CT-0(US)
CT-1(Japan)
LMR(US)
SMR(US)
NMT-450
CT-2(Eur, SEA)
ISM(US)
CT-1/CT-1+(Eur)
AMPS GSM
ETACSNMT-900RC2000
...
GPSDECT(Eur)
PHP (RCR-28)(Japan) ISM
PDC(RCR-27)
DCS-1800(Europe)
PCS(US)
0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400
PCS BandsPCS Bands
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Presentation OutlinePresentation Outline
•• Wireless Definitions and TrendsWireless Definitions and Trends
•• Wireless TelephonyWireless Telephony
•• Quo Vadis Wireless Data?Quo Vadis Wireless Data?
•• Access is the Killer App!Access is the Killer App!
•• Summary and ConclusionsSummary and Conclusions
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Wireless Telephony not Dead!Wireless Telephony not Dead!
•• Exploding Cellular Voice ServicesExploding Cellular Voice Services–– Approximately 40 million subscribers in USApproximately 40 million subscribers in US–– Roughly half of the world’s cellular usersRoughly half of the world’s cellular users–– Similar number of paging subscribers in USSimilar number of paging subscribers in US
–– $7 billion in primary PCS license auctions$7 billion in primary PCS license auctions–– $10.2 billion in secondary PCS auctions$10.2 billion in secondary PCS auctions
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1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
0102030405060708090
100
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
PCSCellular+PCS
Proliferation of Wireless TelephonyProliferation of Wireless Telephony
Millions ofSubscribers
You are here!
Yankee GroupForecast
28000 new AMPS28000 new AMPSsubscribers per daysubscribers per day
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Cellular Phone GrowthCellular Phone Growth
1990 1995 20000
5
10
15
20
25
30
35
40
45
1990 1995 2000
EuropeUnites StatesJapan
% of main linesthat are mobilephones
Year 2000: Mobile phones will reach 42% of fixed-line subscribers
Economist4 May 1996
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Japan UnpluggedJapan Unplugged
86 87 88 89 90 91 92 93 94 95 96 Oct0
2
4
6
8
10
12
14
16
86 87 88 89 90 91 92 93 94 95 96 Oct
# SubscribPHS
Number of mobile phone subscribers in Japan, in March ofNumber of mobile phone subscribers in Japan, in March ofeach year — N.Y. Times, 20 January 1997each year — N.Y. Times, 20 January 1997
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The Lessons of the Japanese The Lessons of the Japanese Cellular Phone SystemCellular Phone System
•• Unexpectedly Rapid GrowthUnexpectedly Rapid Growth–– 1995: ten years to 5.4 million subscribers1995: ten years to 5.4 million subscribers–– March 1996: 10 millionMarch 1996: 10 million–– October 1996: 21 millionOctober 1996: 21 million
•• Why?Why?–– Rapidly declining prices for cell phones & servicesRapidly declining prices for cell phones & services–– Deregulation of Japanese cellular telephone marketDeregulation of Japanese cellular telephone market–– Recent introduction of personal communication Recent introduction of personal communication
services: portable handiphone systemservices: portable handiphone system
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PCS = “Pretty Crazy Situation”?PCS = “Pretty Crazy Situation”?Proposal
CDMA (IS-95)
PCS1900IS-54
OmnipointWACS
DECTPHS
5 MHz CDMA
MobilityHigh
HighHigh
High/LowLow
LowLowLow
SupportersQualcomm, AT&T, Motorola, ALPS,
GSIC, Samsung, Sony, US West, SprintBell Atlantic, Time Warner
Pac Bell, Nokia, MCI, Siemens, KycomAT&T, McCaw
Omnipoint, RockwellBellcore, Motorola, Panasonic, US
West, Sprint, Bell Atlantic, Time WarnerEricsson
NEC, Panasonic, Hitachi, Toshiba, PCSIInterdigital, Oki
•• PCS Primeco (Nynex/Bell Atlantic/US West/Airtouch): CDMA PCS Primeco (Nynex/Bell Atlantic/US West/Airtouch): CDMA•• Wirelessco (Sprint, Comcast, Cox, TCI): CDMA Wirelessco (Sprint, Comcast, Cox, TCI): CDMA•• AT&T Wireless: TDMA AT&T Wireless: TDMA•• Other RBOCs (e.g., PBMS): PCS 1900 (Upbanded GSM) Other RBOCs (e.g., PBMS): PCS 1900 (Upbanded GSM)
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Presentation OutlinePresentation Outline
•• Wireless Definitions and TrendsWireless Definitions and Trends
•• Wireless TelephonyWireless Telephony
•• Quo Vadis Wireless Data?Quo Vadis Wireless Data?
•• Access is the Killer App!Access is the Killer App!
•• Summary and ConclusionsSummary and Conclusions
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Mobile Computing is theMobile Computing is theNatural Evolution Natural Evolution of Computingof Computing
Single UserOS
Batch
Timesharing
Networking
LANs + WSs
Mobile Computing
Freedom from Collocation
MoreFlexibleResourceUsage
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90 91 92 93 94 95 96 97 98 99 00
10
20
30
40
50
60
90 91 92 93 94 95 96 97 98 99 0
Global Markets for Portable ComputersGlobal Markets for Portable Computers$ Billions
You Are Here!Total PC Market: approx. $150 billion
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Laptop Sales, Jan-Sept 1995Laptop Sales, Jan-Sept 1995
0 200,000 400,000 600,000
Toshiba
Compaq
IBM
Apple
NEC
Dell
Zenith
Texas Instr
AST
AT&T Unit Sales(Top 10)
From NYTimes17 Jan 96
556
331
301
203
137
97
75
72
68
46
Approx. 20%Approx. 20%of units areof units are
laptop computerslaptop computers
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A Short History of Wireless DataA Short History of Wireless Data•• Wireless LANsWireless LANs
–– late 1970slate 1970s»» IBM Research--IR for factory apps (<<1 mbps)IBM Research--IR for factory apps (<<1 mbps)»» HP--RF for 100 kbps to distributed terminalsHP--RF for 100 kbps to distributed terminals»» Motorola--1.7 GHz prototype LAN extentionMotorola--1.7 GHz prototype LAN extention
–– 1985: ISM bands opened for low power SS1985: ISM bands opened for low power SS»» Evolves into the PCMCIA formfactor interfaceEvolves into the PCMCIA formfactor interface
–– Recent DevelopmentsRecent Developments»» 1990: Motorola--18 GHz Altair LAN extension1990: Motorola--18 GHz Altair LAN extension»» 1990: IEEE 802.11 Committee Formed1990: IEEE 802.11 Committee Formed»» 1992: Winforum Committee Formed1992: Winforum Committee Formed»» 1992: European ETSI HiperLAN Effort1992: European ETSI HiperLAN Effort»» 1993: Licensed and Unlicensed PCS Bands1993: Licensed and Unlicensed PCS Bands»» 1995: 60 GHz spectrum allocation1995: 60 GHz spectrum allocation
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A Short History of Wireless DataA Short History of Wireless Data•• Wide Area DataWide Area Data
–– ArdisArdis»» 1983: IBM + Motorola; IBM sells out in 19941983: IBM + Motorola; IBM sells out in 1994
»» 1994: 35,000 users, 1300 base stations. 45 million msgs 1994: 35,000 users, 1300 base stations. 45 million msgs per month, 19.2 kbpsper month, 19.2 kbps
–– RAM Mobile Data/MobitexRAM Mobile Data/Mobitex»» Bell South/Ericsson/MotorolaBell South/Ericsson/Motorola
»» 1986: deployed in Sweden1986: deployed in Sweden
»» 1989: 840 base stations, 40 switching centers, in 100 1989: 840 base stations, 40 switching centers, in 100 metro areas, 6300 US cities and towns, 8000 kbps, metro areas, 6300 US cities and towns, 8000 kbps, nationwide roamingnationwide roaming
»» 1994: 12,000 subscribers in US1994: 12,000 subscribers in US
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A Short History of Wireless DataA Short History of Wireless Data•• Wide Area DataWide Area Data
–– CDPDCDPD»» 1991: CDPD patents filed by 3 IBMers (Miller, Moore, 1991: CDPD patents filed by 3 IBMers (Miller, Moore,
Pate, IBM Boca Raton)Pate, IBM Boca Raton)
»» 1993: Initial CDPD specifications, carriers plus IBM. 1993: Initial CDPD specifications, carriers plus IBM. McCaw, IBM, PCSIMcCaw, IBM, PCSI
»» 1995: Deployment of CDPD infrastructure1995: Deployment of CDPD infrastructure
»» 19.2 kbps, make use of idle channels in analog cellular 19.2 kbps, make use of idle channels in analog cellular system via "channel hopping"; TCP/IP compliant with system via "channel hopping"; TCP/IP compliant with support for mobile-IP like mobility routingsupport for mobile-IP like mobility routing
»» Not viewed as a marketing success (yet): where are the Not viewed as a marketing success (yet): where are the subscribers? how pervasive is the coverage?subscribers? how pervasive is the coverage?
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Some ObservationsSome Observations
•• Wireless Data ServicesWireless Data Services–– Have been around for more than 10 yearsHave been around for more than 10 years–– Messaging SystemsMessaging Systems
»» EMBARC, MobileComm, SkyTelEMBARC, MobileComm, SkyTel»» low speed (100s bps), short message, two-way availablelow speed (100s bps), short message, two-way available
–– Wide-Area Data NetworksWide-Area Data Networks»» 100,000 subscribers in US??100,000 subscribers in US??»» RadioMail: Internet E-mail gateway:RadioMail: Internet E-mail gateway:
a few thousand subscribers?a few thousand subscribers?–– Wireless Local Area NetworksWireless Local Area Networks
»» Large number of manufacturers yet small sales volumesLarge number of manufacturers yet small sales volumes»» Approximately 1.2 million units sold to dateApproximately 1.2 million units sold to date
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Technical and Economic ChallengesTechnical and Economic Challenges•• PricingPricing
–– $/airtime, $/data transfer, flat rate?$/airtime, $/data transfer, flat rate?–– Transmitted packets or received packets?Transmitted packets or received packets?–– Artifact provider vs. pipe provider vs. service providerArtifact provider vs. pipe provider vs. service provider
•• PerformancePerformance–– 20 kbps but not quite fast enough for “multimedia”20 kbps but not quite fast enough for “multimedia”–– Coverage, non-interoperabilityCoverage, non-interoperability
•• Killer AppKiller App–– Vertical application vs. email, paging, web accessVertical application vs. email, paging, web access
•• FormfactorFormfactor–– Laptops vs. PDAs vs. Smart PhonesLaptops vs. PDAs vs. Smart Phones
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Promising DevelopmentsPromising Developments
•• Converging PlatformsConverging Platforms–– Smart phones: cellular phone + built-in pager/PDASmart phones: cellular phone + built-in pager/PDA
»» e.g., Nokia/Geoworks “Internet” Phonee.g., Nokia/Geoworks “Internet” Phone
»» e.g., IP-addressable two-way pagers for Narrowband PCSe.g., IP-addressable two-way pagers for Narrowband PCS
•• PCS LicensesPCS Licenses–– Room for Room for allall of those cellular service providers? of those cellular service providers?–– Possible packet data services?Possible packet data services?
•• Emerging Industry StandardsEmerging Industry Standards–– CDPD, IEEE 802.11, WINFORUMCDPD, IEEE 802.11, WINFORUM–– Better interoperation or co-existance in the futureBetter interoperation or co-existance in the future–– 60 GHz allocation60 GHz allocation
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Promising DevelopmentsPromising Developments
•• 60 GHz Allocation60 GHz Allocation–– FCC opens 5 GHz of spectrum at 59-64 GHzFCC opens 5 GHz of spectrum at 59-64 GHz–– Oxygen absorption leads to rapid fall off in signal Oxygen absorption leads to rapid fall off in signal
strength: makes allocation perfect for (very) high strength: makes allocation perfect for (very) high bandwidth WLAN bandwidth WLAN
–– MM Wave Communications Working Group is MM Wave Communications Working Group is defining sharing etiquettedefining sharing etiquette
–– Many technical challenges remain: multipath, Many technical challenges remain: multipath, antenna arraysantenna arrays
–– Many economic challenges remain: high volume Many economic challenges remain: high volume production and reduced costsproduction and reduced costs
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MSC
Promising Developments: GPRSPromising Developments: GPRS
PDA + Modem +Digital Cell Phone
NokiaEricsson
Hewlett PackardGeoworks Software
PCS 1900PacBell Mobile Servicesdeployment in Bay Area
Fall 1996
BSS
ProxyServer
InternetGateway
PSTN
Internet
CellularInfrastructure
General Packet Radio Service (GPRS) of GSM SystemExplicit specification for proxy support services
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Campus Network
Promising Developments: Promising Developments: Wireless CableWireless Cable
Dial-UpRouter
SparcStation
HEM 1110Enc/Mod
RF Upconv
Studio-to-Xmit Link
RLA
Dwinelle Hall“Hybrid POP”
Soda Hall
Router
Coax
“RemoteLink Adapter”
10 Mbps10 Mbpsin 6 MHz
@ 2.4 GHz
Metricom
DownstreamForward Channel
UpstreamReturn Channel
Hybrid RouterDownConverter
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Wireless ATMWireless ATM
•• Uttered in same phrase as Uttered in same phrase as mobile multimediamobile multimedia
•• Switched scalable bandwidth is good thingSwitched scalable bandwidth is good thing
•• But ...But ...–– QoS guarantees incompatible with radio channels: QoS guarantees incompatible with radio channels:
still need to write applications that can adaptstill need to write applications that can adapt–– Mobility presents problems for ATM’s connection Mobility presents problems for ATM’s connection
orientation: connection tear-down and rebuildorientation: connection tear-down and rebuild–– No mechanisms for shared media: implications for No mechanisms for shared media: implications for
costs of the wireless networkcosts of the wireless network
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What Every Happened to What Every Happened to Ubiquitous Computing?Ubiquitous Computing?
•• Computers are getting more ubiquitousComputers are getting more ubiquitous–– Multiple computers in my officeMultiple computers in my office–– Have you been to an airport lately?Have you been to an airport lately?–– Echelon style in-building controls: chip in a light Echelon style in-building controls: chip in a light
socketsocket
•• But it is information, in the form of the web, But it is information, in the form of the web, that has become ubiquitous, not the computer!that has become ubiquitous, not the computer!–– 47 million Americans on the Internet at end of 199647 million Americans on the Internet at end of 1996–– 12 million more than at start of 1996: 34% increase12 million more than at start of 1996: 34% increase
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Wirless Data Success Story: UPSWirless Data Success Story: UPS
•• 60,000 widely dispersed mobile units 60,000 widely dispersed mobile units communicating with a central DB servercommunicating with a central DB server
•• Competitive need for real-time package trackingCompetitive need for real-time package tracking
•• “TotalTrack”: UPS + 100 cellular carriers“TotalTrack”: UPS + 100 cellular carriers–– Cellular modems, bulk service from an alliance of Cellular modems, bulk service from an alliance of
cellular service providers, interfaced to UPSnet, UPS’ cellular service providers, interfaced to UPSnet, UPS’ own packet switched networkown packet switched network
–– Integrated billing, roaming, redundancyIntegrated billing, roaming, redundancy–– ARDIS & RAM rejected due to insufficient coverageARDIS & RAM rejected due to insufficient coverage
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Presentation OutlinePresentation Outline
•• Wireless Definitions and TrendsWireless Definitions and Trends
•• Wireless TelephonyWireless Telephony
•• Quo Vadis Wireless Data?Quo Vadis Wireless Data?
•• Access is the Killer App!Access is the Killer App!
•• Summary and ConclusionsSummary and Conclusions
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AccessAccess is the Killer App is the Killer App
•• Killer CapabilitiesKiller Capabilities–– Access to your desktop environment while on the moveAccess to your desktop environment while on the move–– Be connected whenever possible via the “best” Be connected whenever possible via the “best”
available networkavailable network–– Support the application’s graceful adaptation to the Support the application’s graceful adaptation to the
available bandwidth and latencyavailable bandwidth and latency
•• Technical StrategiesTechnical Strategies–– Continuous Connectivity: Wireless OverlaysContinuous Connectivity: Wireless Overlays–– Proxies: Network- and Type-Aware Applications Proxies: Network- and Type-Aware Applications
Building BlocksBuilding Blocks
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Overlay Network ChallengeOverlay Network ChallengeType of
NetworkBandwidth Latency Mobility Typ Video
PerformanceTyp Audio
PerformanceIn-Building >> 1 Mbps
Comm’l RF: 2 MbpsResearch IR: 50 Mbps
< 3 ms Pedestrian 2-Way ’ractiveFull Frame Rate
(Comp)
High Quality16-bit Samples22 KHz Rate
Campus-AreaPacket Relay
Network
≈ 64 Kbps ≈ 100 ms Pedestrian Med. QualitySlow Scan
Med. QualityReduced Rate
Metro-Area(Wireless
Cable)
10-30 mbps(one way, LOS)
< 10 ms Stationary 2-Way 'ractiveFull Frame Rate
(Compressed)
High Quality16-bit Samples22 KHz Rate
Wide-Area 19.2 Kbps > 100 ms Vehicular Freeze Frame Asynchronous“Voice Mail”
Regional-Area(LEO/DBS/VSAT)
4.8 kbps–10+ Mbps(asymmetric)
> 100 ms VehicularStationary
Seconds/FrameFreeze Frame
Asynchronous“Voice Mail”
Latency as critical as bandwidth in wireless networksWide diversity of network performance parameters
Competing infrastructure providers Pedestrian vs. vehicular mobility
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Application Support ChallengeApplication Support Challenge
Client variation spans an order of magnitudeClient variation spans an order of magnitude
Device Bandwidth,bits/sec
CPU Mem/Disk
Screensize
Bits/pixel
High-endPC
Ethernet(10Mbits),
266 MhzPentium Pro
64/4G 1280x1024 16-24,color
Low-endPC
ISDN (128K) 150 MhzPentium
16/1G 1024x768 8-16,color
High-endnotebook
Cellular (9600)or wireline
800x600 8, color
Low-endnotebook
(28.8K) modem 100 Mhz 486 640x480 4, gray
PDA 2400-14.4Kmodem
20+ MhzRISC or x86
2/0 320x200 1–2, gray
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Wireless Overlay NetworksWireless Overlay Networks
High-tier
Low-tier
Satellite
High Mobility Low MobilityWide Area
Regional Area
Local Area
•• Wireless internetwork: stacked networks Wireless internetwork: stacked networks providing wide area coverage and the best providing wide area coverage and the best possible bandwidth and latencypossible bandwidth and latency
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Proxy ArchitectureProxy Architecture
Proxy
•• ProxyProxy–– Mediates between wireless and wireline environmentMediates between wireless and wireline environment–– Ideally executes at “well-connected” boundaryIdeally executes at “well-connected” boundary–– Manages caches & chooses representations on-the-flyManages caches & chooses representations on-the-fly–– Trade transcoding time against communications timeTrade transcoding time against communications time
Well Connected Poorly Connected
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BARWAN ArchitectureBARWAN Architecture
IPInternet
GW
GW
GW
Server(Correspondent Host)
Proxy Host
Home AgentWireless Subnets
Basestations ForeignAgent
LocalProxy Host
LocalServices
HorizontalHandoff
VerticalHandoff
Overlay IP
•• Overlay IP extends Mobile IPOverlay IP extends Mobile IP•• Proxy/Forwarding Agent InteractionProxy/Forwarding Agent Interaction•• “Vertical” Handoffs between subnetworks“Vertical” Handoffs between subnetworks
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Mobile Applications
“Ses
sio
ns”
Proxy AgentsTransport
(Asymmetric, Heterogeneous, Lossy Links)
LinkScheduling
Wireless LAN
PacketRadio
BARWAN ArchitectureBARWAN Architecture
Mobile IPBeacons
Net ConnectionMonitoring;
Net-ApplInterface;
ELN;
Overlay IP (Mobile IP + Overlays) Lo
cati
on
-Dep
end
ent
Ser
vice
s
Snoop Agent IP
Wire-LessCable
DBSSub-Net
CDPDSub-Net
ATM
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Presentation OutlinePresentation Outline
•• Wireless Definitions and TrendsWireless Definitions and Trends
•• Wireless TelephonyWireless Telephony
•• Quo Vadis Wireless Data?Quo Vadis Wireless Data?
•• Access is the Killer App!Access is the Killer App!
•• Summary and ConclusionsSummary and Conclusions
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SummarySummary
•• Wireless data is Wireless data is notnot dead dead–– Very successful vertical applications like UPSVery successful vertical applications like UPS–– Wide-Area: ISP model vs. “pipe” provider, GPRSWide-Area: ISP model vs. “pipe” provider, GPRS–– Local-Area: Higher b/w, 802.11 standards, etiquetteLocal-Area: Higher b/w, 802.11 standards, etiquette
•• Access is the killer appAccess is the killer app–– Connectivity through wireless overlaysConnectivity through wireless overlays–– Adaptivity through proxy servicesAdaptivity through proxy services
•• IP “Dial Tone”IP “Dial Tone”–– IP to the pager, phone, PDA, laptop, etc.IP to the pager, phone, PDA, laptop, etc.–– Internet service integrationInternet service integration
»» A phone is not a workstation: limited b/w, storage, displayA phone is not a workstation: limited b/w, storage, display
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ConclusionsConclusions
•• Promising Developments:Promising Developments:–– Overlays and ProxiesOverlays and Proxies–– New spectrum allocations for serious bandwidthNew spectrum allocations for serious bandwidth
•• Many of these ideas apply equally well in Many of these ideas apply equally well in today’s heterogeneous network environmentstoday’s heterogeneous network environments–– Asymmetries in satellites and cable modem linksAsymmetries in satellites and cable modem links–– Transport over high bandwidth-delay networksTransport over high bandwidth-delay networks–– High loss links: bandwidth achieved?High loss links: bandwidth achieved?–– Adapt representations to the quality of the end Adapt representations to the quality of the end
device and its network connectivitydevice and its network connectivity