Wireless LAN Technology

Chapter 13Chapter 10 (Pahlavan)

Wideband local wireless networks

WLANCoverage areaData rateBatter consumptionIEEE 802.11 and HIPERLAN

WPANIEEE 802.16, Bluetooth, HomeRF

Data-oriented and voice-oriented MAC

History of LAN Industry

WANs are offered as serviceCost of infrastructureCoverage area

LANs are sold as “end products”You own, no service chargeAnalogy with PSTN/PBX

LAN History-2Emerged to enable sharing of expensive resources such as printers & to ease wiring problemsEarly 1980s: Three standards are developed

802.3 (Ethernet)802.4 (Token Bus)802.5 (Token Ring)

Distinct PHY and MAC layers & topologies, but same management and bridging~1985: Think coax Thin coax TP wiringShorter segments, but ease of installation, lower cost, increased data rate

Thick Coax Installation

Thin Coax Cheaper-net Installation

Hub-and-Spoke Architecture

MAU: Medium Attachment Unit

AUI: Attachment Unit Interface

UTP: Unshielded Twisted Pair

MAU MAUMAU

Thick coax

AUI cable

10 Mbps clients

Terminator

500 m per segment

Server

10 Mbps clients

185 m per segment

Thin coax with BNC T-connector

Server

10BASE-T Repeater

100 m UTP

Server

Figure 10.1: Evolution of the LANs from thick to thin cable and then to star topology using TP.

Need for higher data ratesThick/Think/TP ~ 10MbpsInterconnect LANs in different buildings to share computing resourcesHigh speed multimedia applicationsInterconnect LANsFDDI (fiber distributed data interface): 100 Mbps in mid-1980Mid-1990: 100 Mbps fast Ethernet (802.3)Mid-1990: 100VG-AnyLAN (802.12)Late-1990: Gigabit Ethernet (802.3)

Backbone NetworkBackbone Network

RouterRouter

Figure 10.2: Hierarchical LANs

LAN History-3Mid 1990: ATM LAN (LANE) EmulationIEEE 802 Standards

802.3, 802.4, 802.5 are wired LANs802.9: ISO Ethernet802.6: MAN802.11, 802.15, 802.16: Wireless local net802.14 Cable modem802.10 Security management

Higher Layers

IEEE 802.2 Logical Link Control

802.3MAC

802.3PHY

802.4MAC

802.4PHY

802.5MAC

802.5PHY

802.6MAC

802.6PHY

802.9MAC

802.9PHY

802.11MAC

802.11PHY

802.12MAC

802.12PHY

802.14MAC

802.14PHY

802.15MAC

802.15PHY

802.16MAC

802.16PHY

IEEE 802.1 Bridging

IEEE

802

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802

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Figure 10.3: IEEE 802 Standard Series

WLAN Industry

WLAN vs. WAN Cellular NetworksData rate (2 Mbps vs. 54 Mbps)Frequency band regulation (Licensing)Method of data delivery (Service vs. own)

Early ExperiencesIBM Switzerland

Late 1970Factories and manufacturing floorsDiffused IR technologyCould not get 1 Mbps

HP Labs, Palo Alto1980100 Kbps DSSS around 900 MhzCSMA as MACExperimental licensing from FCCFrequency administration was problematic, thus abandoned

Motorola~19851.73 GHzAbandoned after FCC difficulties

What we learned

Complexity and costBandwidthCoverageInterferenceFrequency administration

Unlicensed BandsFCC dilemma

WLAN requires ~o(10 MHz)WWAN uses 2*25 MHz tens of billions

FCC solutions (mid 1980)Avoid 1-2 GHz, approve higher frequenciesMotorola Altair (18-19 GHz)Release unlicensed frequency bands

ISM bands (May 1985)Public vs private public use etiquette

Products, Bands, Standards

By late 1980s, products with diff. tech.18-19 MHz licensed bandsSpread spectrum technology in ISM bandsIR

802.4L 802.11Shoe-box sized APs (LAN extension)LAN WLAN did not materialize

More bands

WINForum created to obtain more license from FCC

20 MHz in PCS band10 for voice, 10 for dataRules (based on CSMA)

Listen before talkLow transmit powerRestricted duration

Three basic rules1. Listen before talk (or transmit) LBT Protocol

2. Low transmitter power3. Restricted duration of transmissions

Figure 10.4 Unlicensed PCS Bands and their Spectrum Etiquette

Even more bands

1992 HIPERLAN completed23 Mbps200 MHz, 5.15-5.35 & 17.1-17.3 GHzFCC responded by U-NII bands in 1997OFDM based WLANs

Shift in MarketingEarly 1990’s expectation of LAN WLAN shift did not happenTwo new directions1: Boost the power, directional antennas

Cross-building interconnect Alternative (T1) were expensiveRange is fairly good (Tens of kms)

2: Reduce the size to PCMCIA cardTargeted for notebooksUse SS, low power, unlicensed bands

PCMCIA cards and Laptops

Wired Backbone

Building Cross-connect

(b)

(c)

(a) Shoebox type LAN Extension

Figure 10.5 Different forms of WLAN products

(a) LAN-Extension (b) Inter-LAN Bridge (c ) PCMCIA cards for laptops

Shift in MarketingHorizontal vs. vertical integrationTraditionally horizontal (end products)New vertical markets (solutions)

Barcode industryFinancial servicesHealth careWCANs

Horizontal markets now….

New Interest from Military

Mid-1990InfoPADBodyLANSUO/SAS

Figure 10.7: Fusion of Computers and Communications in the

InfoPAD project at the University of California, Berkeley.

Figure 10.8: Body LAN or Wearable LAN

Figure 10.9: The urban/outskirts combat scenario for the SUO-SAS project

New Interest in EU

Incorporate into cellular industryATM-based visionHIPERLAN-2

Explosion in 2000Japan

Small office sizesLaptops replacing PCs

EUWLAN is seen part of the WWAN CellularUnlicensed, high-data rate

USBroadband Internet accessHome networking

Low-power personal networking devices

ConnectionPoint

Smart Home

WLAN

TODAY!Win $ 1000

To fixed network

Intelligent Office

Ad hoc setupPosition Location

Figure 10.11: Wireless Networks: 2000 and Beyond

Wireless Home Networking

Cable, xDSL,Voiceband modem

PSTN

Cable or SatelliteCable Net

Internet

Telephone Wiring

Virtual connection

Figure 10.12: Today’s fragmented home access and distribution networks

0

2

4

6

8

10

12

1998 1999 2000 2001 2002 2003 2004

No. of Homes

Almost doubles each year

Figure 10.13: Growth of the home networking industry

Broadband Home-Access

Internet

Broadband Home-Distribution or Home Area Network (HAN)

Figure 10.14: Two basic technologies needed for home networking

What is a HAN?

PROGRAM

Home ComputingDesktop computerLaptopPrinterScannerQuickCam

Phone appliancesStandard phoneInter CommCordless phone

Location / Navigationlocating children and petsnavigating handicaps

Smart appliancesOven(s)Fridge(s)Washing machine(s)

Entertainment Audio/Visual appliancesAnalog/Digital TVVCR / DVDCamcorderStereo systemSpeakers / Headphones

Security SystemsMotion detectorsDoor pinsSystem control unitCameraAlarm

Utility meteringElectricityGas FuelWater

Figure 10.15: Classification of home equipment demanding networked operation

Why do we need a HAN?

LANs do not provide a good solutionApplications diversityNumber of usersBandwidth requirementsCoverage areaSystem administrationInstallation and maintenance

HAN TechnologiesTP phone lines

Relatively good distributionSuitable for Ethernet connectionAlso used for phone and xDSL

Cable from cable TVPoor distributionUsed for multi-channel TV signal distributionCable-modems are required

Power linesExcellent distributionLine quality is poorFrequency selective channel & impulse noiseData-rate limitations and complex DSP

Wireless IdealBandwidth, coverage, security, interference, reliability etc.

HPNAEthernet compatible LAN over home phone linesStand-alone adapter to connect to any device with 10Base-T interface to phone jacksShares the medium through FDMUp converts the Manchester coding to HPNA bandMAC layer is the same as 802.3Incorporates the legacy hardware and software

Internet

Scanner

Multimedia PCWebphone

telephone

Network camera

Desktop

Printer

Home Gateway Laptop

TV and Set-Up BoxCamera

Figure 10.17 An example of a HPNA network

Figure 10.18: Phone line wirings shared among three technologies using FDM.

(a) POTS uses 20 Hz – 3.4 kHz (b) xDSL uses 25 kHz – 1.1 MHz, and (c) HomePNA uses 2 MHz – 30 MHz

Power Line Modems1 Mbps type ratesAM band is avoidedSome use in smart appliancesInterference, noise, multi-path, fading makes it a challenging medium FSK and QPSK is used for low-ratesOFDM for high ratesCSMA is used as MAC

Figure 10.16: (a) Typical Power line transfer function (b) Typical noise level in the power lines

Narrowbandapplications

Wideband applications

AM radio

3 kHz - 148.5 kHz (EU) HF band (1 -9 kHz - 490 kHz (US)

30 MHz) frequency

Figure 10.19: Frequency bands for low- and high-speed data communications over power lines.

PROGRAM

High speedcomputingSharing Internetconnection, file transfer,share printer

Control networkon/off, light dimmer,HVAC control

Smart appliancesSense other appliances on the power lines, breakdownalert, access through website, email

Security systemsSensors networkthrough power lines

xDSL modem Voice band modem

Cable modem

InternetElectric CompanyLocal Transformer

Meter readingcommunications through outside AC lines to the meter

Headcontrol/security

Figure 10.20: Power lines potential applications

Cable, xDSL, v.90

Home Server

HPNA

Home RF

Internet

Power Line

PROGRAM

Security

Figure 10.21: Evolving Home Area Networks (HAN)

• Wireless

• 802.16

• HIPER-ACCESS

• DBS• Wired

• xDSL

• Cable Modem

Digital Broadcast Satellite

WirelessHybrid Fiber-Coax Network PSTN

Figure 10.23: Broadband home access alternatives

Phone

CablePrinterPrinterCameraCamera Game PadGame Pad

USBUSB

StereoStereo CamcorderCamcorder VCRVCR TVTVMultimedia (e.g. 1394)Multimedia (e.g. 1394)

Grandma’s Brownies3 cups flour1 cup grated chocolate1 cup sugar1 stick butter

HomeRF SWAPHomeRF SWAP

Control Point

HomePNAHomePNA

13941394

Figure 10.22: Vision of the Home RF group at IEEE 802.15.