Wireless Data Networking - Washington University in …jain/talks/ftp/netsem6.pdfThe Ohio State University Raj Jain 10 Frequency Division Multiple Access Frequency band = Channel (as

Raj JainThe Ohio State University

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Wireless DataWireless DataWireless DataWireless DataNetworkingNetworkingNetworkingNetworking

Raj Jain

Professor of Computer and Information SciencesThe Ohio State University

Columbus, OH [email protected]

http://www.cis.ohio-state.edu/~jain/

Ohio Highway Patrol

Raj Jain

jain@cse horizontal


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❑ Terminology

❑ Access Methods

❑ Spread Spectrum

❑ Wireless local area networks

❑ Wireless wide area networks

Note: wireless phone services and standards not covered.

Overview


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Mobile vs WirelessMobile vs Wireless

❑ Mobile vs Stationary

❑ Wireless vs Wired

❑ Wireless ⇒ media sharing issues

❑ Mobile ⇒ routing, addressing issues

Mobile Wireless


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Physical LayerPhysical Layer❑ Analog vs Digital

❑ Infrared, Microwave, Radio

❑ Multiplexing: Frequency, Time, Space, Code division


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Electromagnetic SpectrumElectromagnetic Spectrum100 Hz

1 kHz

10 kHz

100 kHz

1 MHz

10 MHz

100 MHz

1 GHz

10 GHz

100 GHz

1 THz

10 THz

Radio

1014 Hz

1015 Hz

1016 Hz

1017 Hz

1018 Hz

1019 Hz

1020 Hz

1021 Hz

1022 Hz

1023 Hz

1024 Hz

1025 Hz

TV

Wireless

Mic

row

ave

InfraredVisibleUltraviolet

X-Rays

Gamma-Rays


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Spectrum IssuesSpectrum Issues❑ For the same power, lower frequencies travel farther than

higher frequencies ⇒ Short wave for Voice of AmericaMedium wave for local radio

❑ US allocations of spectrum is not the same as in othercountries ⇒ You can’t use the same equipment everywhere

❑ There is a shortage of available spectrum. ⇒ A source of income for the Government ⇒ Spectrum no longer given by lottery but by bids

❑ Federal Government uses up 30% of available spectrum

❑ Earlier communications used up all lower frequencies

❑ Frequencies once considered unusable are now being used.915 MHz, 2.4 GHz, 5.8 GHz


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Other Radio ProblemsOther Radio Problems❑ Broadcast ⇒ Received by all receivers

❑ Air ⇒ Simple to tap the transmission⇒ More subject to security risk

❑ Radio ⇒ Easy to jam

❑ Portable ⇒ Easy to steal, loose, and damage

❑ Easily monitored using scanners

❑ In 1992, 1.7M scanners vs1.3M Phones sold in US

❑ Toronto Study: 80% of cellular traffic monitored

❑ 60% of calls are taped [Boston Globe 4/14/94]⇒ NH Lawyers can't use cellular with clients


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Frequency Division Multiple AccessFrequency Division Multiple Access

❑ Frequency band = Channel (as in TV or Public Radio)

❑ Adjacent Channels ⇒ Interference

❑ Dynamic on-demand allocation of channels

❑ Number of Channels, Arrival rate of calls, Duration of calls,User population ⇒ Blocking probability

❑ Downstream and upstream channels use different frequencybands

❑ FDMA used in all analog systems (including US cellularphone system)

Frequency


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Time Division Multiple AccessTime Division Multiple Access

❑ Adjacent slots ⇒ Synchronization and Interference

❑ TDMA used in IS-54 (GSM)Global System for Mobile Communications (GSM) is adigital cellular radio system

❑ Channel rate = Sum of slot data rate

Time


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Space Division Multiple AccessSpace Division Multiple AccessCellular TechnologyCellular Technology

❑ Repetitive 7-pattern

❑ Cell size 0.5 mile to 10 miles

❑ Terrain topology, weather affects coverage

❑ Smaller cells ⇒ More reuse⇒ More capacity ⇒ Smaller power ⇒ lighter hand sets

❑ Macro (<35km), Micro (<1km), and Pico (<100m) cells


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Frequency Hopping Spread SpectrumFrequency Hopping Spread Spectrum

❑ Pseudo-random frequency hopping

❑ Spreads the power over a wide spectrum⇒ Spread Spectrum

❑ Developed initially for military

❑ Patented by actress Hedy Lamarr

❑ Narrowband interference can't jam

Frequency

Time50 ms


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Fast and Slow FHFast and Slow FH

Time

Frequency

1 0Bits

(a) Fast hopping with 6 hops per bit

Time

Bits

(b) Slow hopping with 3 bits per hop

Frequency

100 101 100 110 110 101 000 001 111 101 110 101


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SpectrumSpectrum

Signal

NoiseSignal

Noise

(a) Normal (b) Frequency Hopping


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Direct-Sequence Spread SpectrumDirect-Sequence Spread Spectrum

❑ Spreading factor = Code bits/data bit10-100 commercial (Min 10 by FCC), 10,000 for military

❑ Signal bandwidth >10 X data bandwidth

❑ Code sequence synchronization

❑ Correlation between codes⇒ Interference ⇒ Orthogonal codes

Frequency

Time5µs

01001011011011010010

Data0 1


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DS SpectrumDS Spectrum

Time Domain Frequency Domain

(a) Data

(b) Code

Frequency

Frequency

Time


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CDMACDMA❑ Advantages:

❑ Little Intereference

✚ Noise can be 18 dB higher than signal

❑ No channel assignment⇒ Frequency reuse in every cell⇒ 20 times more users than FDMA

❑ Enhanced security

❑ Disadvantages:

❑ Code synchronization and tracking

❑ Tight power control to ensure equal power reception atthe base from all mobile

❑ IS-95 US Digital Cellular standard is based on CDMA


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Wireless LANs Market GrowthWireless LANs Market Growth$300M in 1992 to over $1.5B in 1997

❑ Portable computing

❑ Standard interfaces: ISA, PCMCIA

❑ RF technology: Spread Spectrum Multiplexing

❑ FCC spectrum allocation for unlicensed use

❑ 902-928, 2400-2483, 5725-5850 MHz


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Wireless LANsWireless LANs

❑ IR ⇒ Line of sight, short range, indoors

❑ RF ⇒ Need license

❑ Spread-Spectrum: Resistance to interference

1010 1011 1012 1013 1014 1015 1016 1017 1018109

µwave Infrared Vis

ible

Ultraviolet x-rays


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Wireless LANsWireless LANs

Infrared Radio

Spread Spectrum

902 GHz 2.4 GHz

Proxim RangeLANNCR WaveLANTelesystems ArLAN

Motorola ALTAIR

Windata Freeport

PhotonicsCollaborative

InfraLAN

Proxim RangeLAN2

FHDS DS FH

Narrowband

5.7GHz

Line of Sight Diffuse


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Wireless LANs ExamplesWireless LANs ExamplesSystem Medium Rate Protocol RemarkAltair PlusII

18 GhzMicrowave

10 Mbps Ethernet 50 Users/base

RangeLAN Spreadspectrum

242 kbps Proprietary Peer-to-peeror server-based

InfraLAN Infrared 4/16Mbps

Token ring 6 Users perbase, 80’

WaveLAN SpreadSpectrum

2 Mbps Proprietary Peer-to-peer


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Wireless LAN (Mobile) ProductsWireless LAN (Mobile) Products

Product Data Rate Freq-uency

Techno-logy

Range AccessPoints

ATT GIS 2 Mbps 900 MHz DSSS 50 m OptionalIBM 1 Mbps 2/4 GHz FHSS 50 m RequiredProxim 1.6 Mbps 2.4 GHz FHSS 50 m OptionalXircom 1 Mbps 2/4 GHz FHSS 50 m OptionalPhotonics 1 Mbps IR PPM 10 m OptionalSpectrix 4 Mbps IR OCK 10 m Required


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Wireless LANs (fixed)Wireless LANs (fixed)

Product Datarate Freq-uency

Techno-logy

Range AccessPoint

MotorolaAltair

10 Mbps 18 GHz Narrowband

15 m Required

Windata 10 Mbps 2.4, 5.7GHz

DSSS 25 m Required

InfraLAN 4, 10, 16Mbps

IR OCK 25 m Required


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Wireless WAN ServicesWireless WAN Services

❑ 4.8 kbps to 19.2 kbps nominal

❑ Throughput 2 to 8 kbps

❑ Wired backbone using leased lines

❑ Packetized short transmission

❑ Email, stock quotes, weather

❑ Options: ARDIS, RAM Mobile Data, Cellular,Cellular Digital Packet Data (CDPD), NWN, and Metricom


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ARDISARDIS❑ Initially designed for IBM’s field service use only.

❑ Now offered as a service by Motorola and IBM

❑ Available nationwide since April 1990. Covers 8000 cities

❑ In mid-1993: 1300 base stations connected to 35 radio nodecontrollers connected to 3 message switches

❑ Designed for field workers, e.g., UPS uses ARDIS + Cellular

❑ Network Control Processors maintain location information inits area

❑ 800 MHz. Single licensed channel. Being extended.

❑ 4800 bps duplex connections with error correction. 19.2 kbpsavailable at some places.

❑ Good in-building access. 2 W power. 6 hours/charge.


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RAM Mobile DataRAM Mobile Data❑ Uses Mobitex technology developed by Ericson

❑ Adaptation of a specialized mobile ratio (SMR) system with 10to 30 channels per area

❑ Operational in Europe. Started December 92 in North America

❑ By 1993: 800 base stations covering 100 metropolitan areas or90% of US population

❑ Subscriber access via radio to base station

❑ 512 byte packets, per-hop ack

❑ Mobile monitors the reception and reregisters

❑ 8 kbps interface over 12.5 kHz channels

❑ Supports store and forward

❑ In-building penetration and roaming


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Data over CellularData over Cellular❑ US Cellular system is an analog system known as Advanced

Mobile Phone System (AMPS) designed for analog voiceand not data

❑ FDMA, 824-849 MHz Upstream, 869-894 MHzDownstream.

❑ Each channel is 30 kHz wide⇒ Two sets of 333 duplex channelsOne set for wireline and one for non-wireline carrier

❑ Need data-compatible cellular phone,and cellular compatible modem

❑ Handover times of 300 ms or longer⇒ Connections can be broken if you change the locationor if another user initiates a call


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Cellular Digital Packet Data (CDPD)Cellular Digital Packet Data (CDPD)❑ Originally named “Celluplan” by IBM

❑ Allows data to use idle channels on cellular system

❑ Data hops from one channel to next as the channels becomebusy or idle

Voice CallIdle Channel

Data packets


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CDPDCDPD❑ Backed by 9 major service providers

❑ Nationwide cellular packet data service

❑ Connectionless and connection-oriented serviceConnectionless ⇒ No ack, no guaranteesConnection-oriented ⇒ reliable delivery, sequencing, flowcontrol

❑ Point-to-point and multipoint connections

❑ Uses only idle 30 kHz channels in the cellular system

❑ Quickly hops-off a channel grabbed by cellular system

❑ Currently, extra channels dedicated for CDPD

❑ Subscriber unit (SU) registers on power-up and periodically

❑ Deregisters before power-down

❑ Subscriber unit initiates handoff


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MetricomMetricom❑ Spread-Spectrum in the 902-928 MHz band

❑ In-building, campus, and metropolitan area networking

❑ Nearby units can communicate directly.

❑ If the intended destination is not directly reachable, go via a“node” through the network. Up to 56 kbps.

❑ Nodes are cheap (less than $1000)

❑ You can have a campus network of your own with aconnection to the Metricom’s metropolitan area network

❑ Flat monthly rate based on speed only

Ref: http://www.metricom.com/ricohom.html


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Nationwide Wireless Network (NWN)Nationwide Wireless Network (NWN)❑ Being designed by Mtel (owners of SkyTel)

❑ Two-way messaging

❑ Can acknowledge your page directly using the pager

❑ Main issue: Pager’s transmit power is limited and muchsmaller compared to the power of the base

❑ Outbound 50 kHz channel similar to SkyPage systemUses high powered base transmitters in metropolitan areas

❑ Inbound 12.5 kHz: Each base transmitter’s area covered bymultiple (inexpensive) receivers

❑ Awarded a “Pioneer’s Preference License” for a 900 MHzfrequency


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SummarySummary

❑ Multiplexing: TDMA, FDMA, SDMA, CDMA

❑ CDMA = Spread spectrum: Frequency hopping or directsequence

❑ LAN Alternatives: Photonics, RangeLan, ALTAIR

❑ WAN Alternatives: ARDIS, RAM, Cellular, CDPD,Metricom, NWN


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References: BooksReferences: Books❑ A.M. Seybold, "Using Wireless Communications in

Business," Van Nostrand Reinhold, 1994, 216 pp.

❑ P.T. Davis and C.R. McGuffin, "Wireless Local AreaNetworks," McGraw-Hill, 1994, 250 pp.

❑ P. Wong and D. Britland, "Mobile Data CommunicationsSystems," Artech House, 1995, 190 pp.

❑ I. Brodsky, "Wireless: The Revolution in PersonalTelecommunications," Artech House, 1995, 276 pp.

❑ J. Gardiner and B. West, Ed., "Personal CommunicationSystems and Technologies," Artech House, 1995, 238 pp.

❑ R. Sneiderman, "Wireless Personal Communications: TheFuture of talk," IEEE Press, 1994, 195 pp.


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❑ S.M. Redl, M.K. Weber, and M.W. Oliphant, "AnIntroduction to GSM," Artech House, 1995, 379 pp.

❑ R.C. Dixon, "Spread-Spectrum Systems with CommercialApplications," Wiley, 1994, 573 pp.

❑ B. Bates, “Wireless Networked Communications,”McGraw-Hill, 1994, 295 pp.

❑ J. Walker, (Ed), “Mobile Information Systems, ArtechHouse, Boston,” 1990

❑ R.C.V. Macario (Ed), “Personal & Mobile Radio Systems,”IEE, UK 1991

❑ J.D. Parsons and J.G. Gardiner, “Mobile CommunicationsSystems,” Halsted Press, New York, 1989

❑ G. Calhoun, "Digital Cellular Radio," Artech House, 1988,445 pp.


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References: On-lineReferences: On-line❑ The WWW Virtual Library: Mobile and Wireless Computing,

http://snapple.cs.washington.edu:600/mobile/mobile_www.html

❑ Mobile computing,http://www.yahoo.com/Computers/Mobile_Computing/

❑ Wireless companies,http://www.yahoo.com/Business/Corporations/Telecommunications/Wireless/

❑ Wireless news group: comp.std.wireless

❑ RAM Mobile Data, http://www.ram.co.uk/


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ReferencesReferences❑ G.H. Forman and J. Zahorjan, "The Challanges of Mobile

Computing," Computer, April 1994

❑ D.F. Bantz, “Wireless LAN Design Alternatives,” IEEENetwork, March/April 1994, pp. 43-53.

❑ K. Pahlavan, T.H. Probert, and M.E. Chase, “Trends inLocal Wireless Networks,” IEEE CommunicationsMagazine, March 1995, pp. 88-95.

❑ E. Links. W. Diepstraten and V. Hayes, “Universal WirelessLANs,” Byte, May 1994, pp. 99-108.

❑ B. Jabbari, et al, “Network Issues for WirelessCommunications,” IEEE Communications Magazine,January 1995, pp. 88-98.


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References (Cont.)References (Cont.)❑ R.H. Katz, “Adaptation and Mobility in Wireless

Information Systems,” IEEE Personal Communications,First Quarter 1994, pp. 6-17.

❑ K.C. Chen, “Medium Access Control of Wireless LANs forMobile Computing,” IEEE Network, September/October1994, pp. 50-63.

❑ C.A. Rypinski, “Standards Issues for Wireless Access,”Business Communications Review, August 1992, pp. 40-45.

❑ G. Fay, “Wireless Data Networking,” International Journalof Network Management, 8 March 1992, pp. 8-17.


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References (Cont.)References (Cont.)❑ D.J. Goodman, “Second Generation Wireless Information

Networks,” IEEE Transactions on Vehicular Technology,Vol. 40, No. 2, May 1991

❑ D. Buchholz, et al, “Wireless In-Building NetworkArchitecture and Protocols,” IEEE Network Magazine,November 1991, pp. 31-38.

❑ V. Hayes, “Standardization Efforts for Wireless LANs,”IEEE Network Magazine, November 1991, pp. 19-20.

❑ D.J. Goodman, “Cellular Packet Communication,” IEEETransactions on Communications, August 1990, pp. 1272-1280.


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Wireless LAN/WAN ProductsWireless LAN/WAN Products❑ Adaptec: Airport NIC

❑ Aironet Wireless Communications: ArLAN 630, 631, 640 Hubs

❑ Alps America: RadioPort Plus, RadioPort/parallel NICs

❑ AT&T:

❑ Safari Wireless Mailbox

❑ TransTalk 9000 Wireless Communications System (Switch)

❑ WaveLAN/WavePoint NIC

❑ Wireless Medium Access Controller NIC

❑ Wireless Services Flashpoint (Hand-Held Data Device)

❑ Wireless Subscriber System (Telecom Equipment)


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Wireless LAN/WAN Products (Cont.)Wireless LAN/WAN Products (Cont.)❑ Cabletron Systems: Freelink/62 Wireless Ethernet Hub

❑ Cincinnati Microwave: MC-Dart 100, PC-Dart 200 Modems

❑ Cylink: Airlink Bridge Hub

❑ Data Race: Wireless Redidockit NIC

❑ Dauphin Technology: DTR-1/GPS/LAN/WAN NICs

❑ Dayna Communications:

❑ Daynacomm Roamer PCMCIA/Serial NIC

❑ Network Access Point NIC

❑ DEC:

❑ RoamAbout Access Point ISA/PCMCIA NICs

❑ WaveLAN NIC


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Wireless LAN/WAN Products (Cont.)Wireless LAN/WAN Products (Cont.)❑ Diablo Research: Mxlink/Mylink modems

❑ Digital Ocean: Grouper100D/100Lt/100Mp/110Mp/NB/Manta/Starfish NICs

❑ Ericsson: M2190 (Wireless Modem)

❑ Extended Systems: JetEye NICs

❑ Fluke: Wireless Logger (Data Collection Device)

❑ Goldmine: Wireless Solution (Remote Access Software)


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Wireless LAN/WAN Products (Cont.)Wireless LAN/WAN Products (Cont.)❑ IBM:

❑ AS/400 Wireless LAN

❑ Infrared NICs

❑ Thinkpad Wireless fax modem

❑ Wireless LAN Entry

❑ Wireless modems for ARDIS/Cellular/CDPD/Mobitex

❑ Wireless RF LANs

❑ Intel: Wireless modem

❑ K&M Electronics: Airplex wireless fax modem jack

❑ Kantek Spectrum: 3-D Wireless Ringmouse (Mouse)

❑ Travelling Software: LapLink Wireless (file transfer S/W)


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Wireless LAN/WAN Products (Cont.)Wireless LAN/WAN Products (Cont.)❑ Laser Communications:

❑ InfraLAN NIC

❑ Omnibeam 4000 Network

❑ LXE 5420/5460 wireless modems

❑ LXE RF ID NIC

❑ Merritt Computer Products: Cordless printer sharing kit

❑ Metricom: Ricochet wireless modem

❑ Momentum Microsystems: PC-Linx NIC


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Wireless LAN/WAN Products (Cont.)Wireless LAN/WAN Products (Cont.)❑ Motorola:

❑ ALTAIR Plus wireless Ethernet NIC

❑ ALTAIR wireless Ethernet NIC

❑ Cellect 14.4 PCMCIA (wireless fax modem)

❑ Envoy Wireless Communicator (PDA)

❑ Infotac Two-Way Messenger (wireless modem)

❑ Wireless In-Building Network

❑ NEC: Wireless PBX

❑ Northgate Computer Systems: Wireless LAN

❑ Notable Technologies: Airnote wireless modem

❑ O'Neill Communications: Local Area Wireless Network


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Wireless LAN/WAN Products (Cont.)Wireless LAN/WAN Products (Cont.)❑ Olivetti: Wireless LAN

❑ Persoft: Intersect Remote Bridge

❑ Photonics Collaborative: Wireless LAN/WAN System

❑ Proxim:

❑ Proxlink NIC

❑ RangeLan/RangeLAN2 ISA/PCMCIA LANs

❑ RangeLink bridge/router

❑ Radlinq: WL-4000/5000/6000 wireless routers

❑ RDC Communications: PortLAN modem

❑ Sierra Wireless: PocketPlus (wireless fax modem)

❑ Silcom Manufacturing Technology: FreeSpace NIC


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Wireless LAN/WAN Products (Cont.)Wireless LAN/WAN Products (Cont.)❑ SkyTel: Skycard NIC

❑ Socket Communications: Pagecard wireless messaging system

❑ Solectek: Airlan Parallel/PCMCIA LAN/CAN NIC/bridge

❑ Spectrix: SpectrixLite NIC

❑ Spreadnet: Wireless Link (WAN Adapter)

❑ Telesystems: SLQ ArLAN 680 NIC

❑ Toshiba: Wireless Portable Workgroup (Pre-Packaged LAN)

❑ Triquint Semiconductor: TQ9205/TQ9206 NIC

❑ U.S. Robotics: Worldport dual standard PCMCIA (wirelessmodem)


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Wireless LAN/WAN Products (Cont.)Wireless LAN/WAN Products (Cont.)❑ U.S. Wireless: Data POS-50 (point-of-sale terminal)

❑ USEMCO Technologies: Mobile Trader (wireless modem)

❑ Windata:

❑ Airport I/II (wireless LAN systems)

❑ Airport Wireless Interbuilding Systems (pre-packagedLAN)

❑ Freeport wireless hub/LAN/transceivers

❑ Xircom: NetWave NICs

❑ Zenith Data Systems: CruiseLan ISA/PCMCIANICs/bridges/routers

❑ Zyxel USA: U-1496P portable cellular fax Modem

Documents

Wireless Data Networking - Washington University in …jain/talks/ftp/netsem6.pdfThe Ohio State University Raj Jain 10 Frequency Division Multiple Access Frequency band = Channel (as