WIRELESS LAN Presented by Ching-Man Chong Tracy Tien Johnny Wong Zhong Wei Yu.

WIRELESS LANWIRELESS LAN

Presented byPresented by

Ching-Man ChongChing-Man Chong

Tracy TienTracy Tien

Johnny WongJohnny Wong

Zhong Wei YuZhong Wei Yu


WIRLESS LOCAL AREA WIRLESS LOCAL AREA NETWORKNETWORK


IntroductionIntroduction Wireless TechnologyWireless Technology Wireless LAN Wireless LAN ConfigurationConfiguration Differences between wired LAN vs Differences between wired LAN vs

wireless LANwireless LAN Cost-Benefit StudyCost-Benefit Study Customer ConsiderationsCustomer Considerations

INTRODUCTIONINTRODUCTION Data communications system Data communications system Alternates wired LANAlternates wired LAN Transmits and receives data over the air Transmits and receives data over the air Minimize the need for wired connectionsMinimize the need for wired connections Become more popular in general-purpose Become more popular in general-purpose

alternative of business customers.alternative of business customers. Benefited several industries in Benefited several industries in

productivity and mobilityproductivity and mobility

WHY WIRELESS?WHY WIRELESS?

Advantages:Advantages:

MOBILITYMOBILITY INSTALLATIONINSTALLATION COSTCOST SCALABILITYSCALABILITY

MOBILITYMOBILITY

Real-time information access from Real-time information access from anywhere at any timeanywhere at any time

Increases productivity and Increases productivity and flexibilityflexibility

INSTALLATIONINSTALLATION

Fast and easy Fast and easy No cable neededNo cable needed No frustration with wiringNo frustration with wiring Go where wires cannot goGo where wires cannot go

COSTCOST

Short runShort run– Initial investment is higher than wired Initial investment is higher than wired

LANLAN Long runLong run

– Long-term costs is essentially lower Long-term costs is essentially lower than wired LAN than wired LAN

– Long-term cost and benefits are very Long-term cost and benefits are very important in dynamic and ever-important in dynamic and ever-changing business environmentschanging business environments

SCALABILITYSCALABILITY

Can be configured in different Can be configured in different topologies to meet the specification of topologies to meet the specification of applications and installationsapplications and installations

Can be easily changed from peer-to-Can be easily changed from peer-to-peer networks (small # of users) to full peer networks (small # of users) to full infrastructure networks (thousands of infrastructure networks (thousands of users)users)

IN THE REAL WORLD IN THE REAL WORLD Not a replacement for the wired Not a replacement for the wired

infrastructure infrastructure Great complement to what currently exists Great complement to what currently exists Examples Examples

– Doctors and nursesDoctors and nurses more productive in delivering patients’ information and more productive in delivering patients’ information and

status instantlystatus instantly

– StudentStudent access the Internet to consult the catalog of the access the Internet to consult the catalog of the

Library of CongressLibrary of Congress– Network managersNetwork managers

provide backup for mission-critical applicationsprovide backup for mission-critical applications

HOW IT WORKSHOW IT WORKS

Use electromagnetic airwaves to Use electromagnetic airwaves to communicate informationcommunicate information

Data imposed on radio carrier (radio Data imposed on radio carrier (radio wave)wave)

RF electromagnetic wave can RF electromagnetic wave can easily pass through ordinary wall, easily pass through ordinary wall, it needs to implement with heavy it needs to implement with heavy concrete or metal screening.concrete or metal screening.

WIRELESS TECHNOLOGYWIRELESS TECHNOLOGY

WIRELESS TECHNOLOGYWIRELESS TECHNOLOGY

Satellite-Based System Satellite-Based System – Geosynchronous Earth Orbiting (GEO)Geosynchronous Earth Orbiting (GEO)– Low Earth Orbiting (LEO)Low Earth Orbiting (LEO)

Land-Based Network Access Land-Based Network Access SystemSystem– Wireless WAN Wireless WAN – Wireless LANWireless LAN

GEO SATELLITESGEO SATELLITES

Circle the earth from a height of Circle the earth from a height of 22,300 miles22,300 miles

3 satellites can be used to provide 3 satellites can be used to provide worldwide coverageworldwide coverage

used for:used for:– television broadcasts, long distance television broadcasts, long distance

telecommunications, and various telecommunications, and various science and military applicationsscience and military applications

LEO SATELLITESLEO SATELLITES

Orbit no higher than 500 miles Orbit no higher than 500 miles above the earthabove the earth

Travel the earth in a couple of Travel the earth in a couple of hourshours

Multiple satellites neededMultiple satellites needed Allow access to very low-power Allow access to very low-power

devicesdevices

WIRELESS WANWIRELESS WAN

Provide nationwide or citywide Provide nationwide or citywide coveragecoverage

Example: Ricochet Micro-CellExample: Ricochet Micro-Cell

Source: http://dcs.umd.edu

Coverage in Washington D.C., San Francisco, and Seattle


Wireless LAN TopologyWireless LAN Topology– 2 main components2 main components

Access PointsAccess Points AdaptersAdapters

– RoamingRoaming Wireless LAN TechnologyWireless LAN Technology

– TypesTypes– StandardStandard– ConfigurationConfiguration

ACCESS POINTSACCESS POINTS

Connects to the wired network Connects to the wired network single access point can support a single access point can support a

small group of users within a range small group of users within a range of several hundred feetof several hundred feet


Wireless Clients Connected to LAN via Access Point

ADAPTERSADAPTERS

Users used wireless-LAN adapters Users used wireless-LAN adapters to connect to access pointsto connect to access points

Implemented as :Implemented as :– PC cards in notebook computers PC cards in notebook computers – ISA or PCI cards in desktop computersISA or PCI cards in desktop computers– Integrated within hand-held Integrated within hand-held

computerscomputers

ROAMINGROAMING

Each access point can provide Each access point can provide between 50,000 to 250,000 square between 50,000 to 250,000 square feet of coveragefeet of coverage

Example: Hospital EnvironmentExample: Hospital Environment


WIRELESS LAN WIRELESS LAN TECHNOLOGYTECHNOLOGY

Narrowband TechnologyNarrowband Technology Spread Spectrum TechnologySpread Spectrum Technology

– Frequency-Hopping Spread Spectrum Frequency-Hopping Spread Spectrum TechnologyTechnology

– Direct-Sequence Spread Spectrum Direct-Sequence Spread Spectrum TechnologyTechnology

Infrared TechnologyInfrared Technology

NARROWBAND NARROWBAND TECHNOLOGYTECHNOLOGY

Transmits and receives user Transmits and receives user information on a specific radio information on a specific radio frequencyfrequency

keeps the radio signal frequency as keeps the radio signal frequency as narrow as possiblenarrow as possible

Radio receiver filters out all radio Radio receiver filters out all radio signals except the ones on its signals except the ones on its designated frequencydesignated frequency

Example: private telephone linesExample: private telephone lines

SPREAD SPECTRUM SPREAD SPECTRUM TECHNOLOGYTECHNOLOGY

Mostly used in wireless LAN Mostly used in wireless LAN systemsystem

Trades of bandwidth efficiency for Trades of bandwidth efficiency for reliability, integrity, and securityreliability, integrity, and security

Signal looks like background noise Signal looks like background noise if not turned to the right frequencyif not turned to the right frequency

FREQUENCY-HOPPING FREQUENCY-HOPPING SPREAD SPECTRUM SPREAD SPECTRUM

TECHNOLOGYTECHNOLOGY

Uses a narrowband carrier that Uses a narrowband carrier that changes frequency in a pattern changes frequency in a pattern known to both transmitter and known to both transmitter and receiverreceiver

Maintain a single logical channelMaintain a single logical channel

FREQUENCY-HOPPING SPREAD FREQUENCY-HOPPING SPREAD SPRECTRUM TECHNOLOGYSPRECTRUM TECHNOLOGY

(con’t)(con’t)

Source: www.wlana.com

DIRECT-SEQUENCE DIRECT-SEQUENCE SPREAD SPECTRUM SPREAD SPECTRUM

TECHNOLOGYTECHNOLOGY

Generates a redundant bit (chip) Generates a redundant bit (chip) pattern for each bit to be transmittedpattern for each bit to be transmitted

The longer the chip, the greater the The longer the chip, the greater the probability that the original data can probability that the original data can be recoveredbe recovered

To unintended receivers:To unintended receivers:– Viewed as low-power wideband noise Viewed as low-power wideband noise – Rejected by most narrowband receiversRejected by most narrowband receivers

DIRECT-SEQUENCE SPREAD DIRECT-SEQUENCE SPREAD SPECTRUM TECHNOLOGY SPECTRUM TECHNOLOGY

(con’t)(con’t)


INFRARED (IR) INFRARED (IR) TECHNOLOGYTECHNOLOGY

Little used in commercial wireless LANsLittle used in commercial wireless LANs Use very high frequenciesUse very high frequencies Inexpensive, but provide very limited Inexpensive, but provide very limited

range (3ft)range (3ft) Typically used for personal area Typically used for personal area

networksnetworks Used only to implement fixed Used only to implement fixed

subnetworkssubnetworks

WIRELESS STANDARDWIRELESS STANDARD

IEEE 802.11IEEE 802.11– represent the 1st standard for wireless represent the 1st standard for wireless

LANLAN– standardize radio equipment and standardize radio equipment and

networks operating system for wireless networks operating system for wireless LANLAN

– Addresses for:Addresses for: Physical (PHY) layer Physical (PHY) layer Media Access Control (MAC)Media Access Control (MAC)

CONFIGURATIONCONFIGURATION

Peer-to-peer networkPeer-to-peer network Client and Access pointClient and Access point Multiple access points and roamingMultiple access points and roaming Using an extension pointUsing an extension point Using directional antennas Using directional antennas

PEER-TO-PEER NETWORKPEER-TO-PEER NETWORK

Wireless adapter cardsWireless adapter cards– Connect 2 PCsConnect 2 PCs

Client access only to each other, Client access only to each other, not with a central servernot with a central server

Source: http://www.proxim.com

CLIENT & ACCESS POINT CLIENT & ACCESS POINT (AP)(AP)

Access pointAccess point– Must be wired to the Must be wired to the

networknetwork– Extend the range of Extend the range of

the networkthe network– Allow access from Allow access from

client-to-server and client-to-server and among each among each workstationworkstation

– Real-world: each Real-world: each Access Point can Access Point can accommodate from 15-accommodate from 15-50 client devices50 client devices


MULPTIPLE AP & ROAMINGMULPTIPLE AP & ROAMING

In large facility, more than one AP In large facility, more than one AP might be needed to coverage the might be needed to coverage the whole areawhole area

Access Point range: Access Point range: – Indoor = 500 ft; Outdoor = 1,000 ftIndoor = 500 ft; Outdoor = 1,000 ft


EXTENTION POINT (EP)EXTENTION POINT (EP) EP can be connected to the EP can be connected to the

network without wiring. network without wiring. EP extend the range of the EP extend the range of the

network by relaying signals from a network by relaying signals from a client to an AP or another EP.client to an AP or another EP.


DIRECTIONAL ANTENNASDIRECTIONAL ANTENNAS

Extend the wireless networks Extend the wireless networks between buildingsbetween buildings

Antenna must be connected to an Antenna must be connected to an AP of the networkAP of the network


PHYSICAL LAYERPHYSICAL LAYER

MEDIUM ACCESS MEDIUM ACCESS CONTROLCONTROL

A collision may occur when 2 stations A collision may occur when 2 stations transmit data simultaneouslytransmit data simultaneously

Detects the collision and ignores the Detects the collision and ignores the messagemessage

Each station that wants to transmit waits a Each station that wants to transmit waits a random amount of time and then attempts random amount of time and then attempts to transmit againto transmit again

The random transmission delays reduce the The random transmission delays reduce the probability that the stations will transmit probability that the stations will transmit simultaneously again.simultaneously again.

DIFFERENCES BETWEEN DIFFERENCES BETWEEN

WIRED LAN WIRED LAN

ANDAND


WIRED vs. WIRELESS LANWIRED vs. WIRELESS LAN

WiredWired– Link clients, Link clients,

printers, and printers, and network network equipment equipment using cablesusing cables

WirelessWireless– Basic building Basic building

block is the block is the CellCellSource:

www.breezecom.com

WIRED

WIRELESS

WIRE vs. WIRELESS (con’t)WIRE vs. WIRELESS (con’t)

BridgingBridging– WiredWired

Access point connects Access point connects to the backbone of a to the backbone of a wired Ethernet LAN wired Ethernet LAN via a simple cablevia a simple cable

– WirelessWireless can be mounted can be mounted

back-to-back with an back-to-back with an access point access point

Able to link buildings Able to link buildings that are miles apartthat are miles apart

Source: www.breezecom.com

WIRED vs.WIRED vs. WIRELESS WIRELESS (con’t)(con’t)

Cells Cells – Linked Cells (Wired)Linked Cells (Wired)

user can walk from user can walk from Cell A to overlap Cell Cell A to overlap Cell B without interrupting B without interrupting a work sessiona work session

– Multi-cells (Wireless)Multi-cells (Wireless) Position Access Position Access

Points at different Points at different locations in the locations in the coverage areas with coverage areas with their directional their directional antennasantennas

Source: www.breezecom.com

WHEN DO YOU NEED WHEN DO YOU NEED WIRELESS LAN WIRELESS LAN TECHNOLOGY?TECHNOLOGY?

WHEN?WHEN?

When you truly need mobilityWhen you truly need mobility When you plan to move or remodel When you plan to move or remodel

soonsoon When set up a portable buildings for When set up a portable buildings for

temporary usetemporary use When you don’t have time to configure When you don’t have time to configure

and maintain a wiring schemeand maintain a wiring scheme When running cable is too expensiveWhen running cable is too expensive

Cost-Benefit StudyCost-Benefit Study

COST-BENEFIT STUDYCOST-BENEFIT STUDY

89% successful implementation 92% of respondents believe the

definite economic and business benefit after installation

92% continue to deploy wireless technology in their network

Payback was less than 1 year across all industries surveyed.


COST/BENEFIT STUDY COST/BENEFIT STUDY (con’t)(con’t)

Economic BenefitsEconomic Benefits– PaybackPayback


COST/BENEFIT STUDY COST/BENEFIT STUDY (con’t)(con’t)

Broad cross-section of the Broad cross-section of the representative industries with representative industries with successful implementation of wireless successful implementation of wireless LANLAN– Education: 23%Education: 23%– Healthcare: 23%Healthcare: 23%– Manufacturing/Warehouse: 21%Manufacturing/Warehouse: 21%– Retail: 15%Retail: 15%– Financial/Office Automation: 18%Financial/Office Automation: 18%Source: www.wlana.com

Wireless LAN MarketWireless LAN Market

WIRELESS LAN MARKETWIRELESS LAN MARKET Customer considerationsCustomer considerations

– Range and coverageRange and coverage– ThroughputThroughput– CompatibilityCompatibility– InteroperabilityInteroperability– Interference and CoexistenceInterference and Coexistence– Licensing issuesLicensing issues– SimplicitySimplicity– SecuritySecurity– CostCost– Major vendorsMajor vendors– ScalabilityScalability

Customer ConsiderationsCustomer Considerations

CUSTOMER CUSTOMER CONSIDERATIONSCONSIDERATIONS

Range and coverageRange and coverage– Mostly use Radio Frequency because Mostly use Radio Frequency because

it can penetrate most indoor walls it can penetrate most indoor walls and obstaclesand obstacles

– Range varies from under 100 feet to Range varies from under 100 feet to more than 300 feetmore than 300 feet

– Coverage can be extendedCoverage can be extended

CUSTOMER CUSTOMER CONSIDERATIONS (con’t)CONSIDERATIONS (con’t)

ThroughputThroughput– Actual throughput is product and set-Actual throughput is product and set-

up dependentup dependent– Affecting factors:Affecting factors:

# of users# of users Range and multipathRange and multipath Type of wireless LAN system usedType of wireless LAN system used


Compatibility with existing networkCompatibility with existing network– Most wireless LANs provide industry-Most wireless LANs provide industry-

standard interconnection with wired standard interconnection with wired networks such as Ethernet or Token networks such as Ethernet or Token Ring.Ring.

– Wireless LAN nodes are supported by Wireless LAN nodes are supported by network operating systems through network operating systems through uses of appropriate drivers. uses of appropriate drivers.


Interoperability of wireless devicesInteroperability of wireless devices– Different vendors might not be Different vendors might not be

interoperableinteroperable Three reasonsThree reasons

– System based on spread spectrum frequency System based on spread spectrum frequency hopping (FHSS) will not communicate with hopping (FHSS) will not communicate with direct sequence (DSSS).direct sequence (DSSS).

– Different frequency bands will not Different frequency bands will not interoperate even with same technology.interoperate even with same technology.

– Differences in implementation.Differences in implementation.


Interferences and CoexistenceInterferences and Coexistence– Unlicensed wireless transmitting Unlicensed wireless transmitting

energy in same frequency spectrum energy in same frequency spectrum can provide interference. (ex. can provide interference. (ex. Microwave oven)Microwave oven)

– Co-location of multiple wireless LANs: Co-location of multiple wireless LANs: more wireless LANs, more more wireless LANs, more interferences.interferences.

CUSTOMER CUSTOMER CONSIDERATIONS (con’t)CONSIDERATIONS (con’t) LicensingLicensing

– Federal Communications Commission (FCC)Federal Communications Commission (FCC)– Wireless LANs operate in portions of radio Wireless LANs operate in portions of radio

spectrum: end user does not require license.spectrum: end user does not require license.– Manufacturer must ensure certification by Manufacturer must ensure certification by

agency in that country to distribute the use of agency in that country to distribute the use of wireless LANs.wireless LANs.

– In US: broadcast over ISM (Instrumentation, In US: broadcast over ISM (Instrumentation, Scientific, and Medical) bands. Scientific, and Medical) bands.

Bands: 902-928MHz, 2.4-2.483 GHz, 5.15-5.35 Bands: 902-928MHz, 2.4-2.483 GHz, 5.15-5.35 GHz, 5.725-5.875 GHz.GHz, 5.725-5.875 GHz.

CUSTOMER CUSTOMER CONSIDERATIONS (con’t) CONSIDERATIONS (con’t)

SimplicitySimplicity– Wireless is transparent to users.Wireless is transparent to users.– Applications is same with wired LANs.Applications is same with wired LANs.– Only access points is require cabling.Only access points is require cabling.– Portable from place to place after Portable from place to place after

configured.configured.


SecuritySecurity– Complex encryption techniques is Complex encryption techniques is

used.used.– Individual nodes must be security Individual nodes must be security

enable before they are allowed to enable before they are allowed to participate in network traffic.participate in network traffic.


CostCost– Infrastructure costsInfrastructure costs

Wireless access points.Wireless access points. Number of access points deployed Number of access points deployed

($1,000 to $2,000).($1,000 to $2,000). Coverage region/type of users serviced.Coverage region/type of users serviced.

– User costsUser costs Wireless LAN adapters. Wireless LAN adapters. Price range from $300 to $1,000.Price range from $300 to $1,000.

CUSTOMER CUSTOMER CONSIDERTAIONS (con’t)CONSIDERTAIONS (con’t)

Cost of Installation and Cost of Installation and MaintenanceMaintenance– Lower direct costLower direct cost

Eliminates direct costs of cabling, labor Eliminates direct costs of cabling, labor associated with installing and repair. associated with installing and repair.

– Lower indirect costLower indirect cost Reduce indirect costs of user downtime Reduce indirect costs of user downtime

and administrative overhead as it simplify and administrative overhead as it simplify moves, adds, and changesmoves, adds, and changes


MAJOR VENDORSMAJOR VENDORS– 6 major vendors for the wireless LAN6 major vendors for the wireless LAN

AironetAironet AMDAMD Digital Equipment CorporationDigital Equipment Corporation Harris SemiconductorHarris Semiconductor Intermec Technologies CorporationIntermec Technologies Corporation Lucent TechnologiesLucent Technologies


ScalabilityScalability– Adding access points: to extend Adding access points: to extend

coverage.coverage.

SUMMARY OF THE SUMMARY OF THE PROJECTPROJECT

More to discover about wireless More to discover about wireless LANLAN

Wireless is very popular and Wireless is very popular and excitingexciting

Much knowledge was gained Much knowledge was gained through this projectthrough this project

ReferencesReferences dcs.umd.edu/telecom/library/paper.htmldcs.umd.edu/telecom/library/paper.html www.biz.uiowa.edu www.biz.uiowa.edu www.blackbox.comwww.blackbox.com www.breezecom.com/TechSupport/brztov.htmwww.breezecom.com/TechSupport/brztov.htm www.geocities.com/CapeCanaveral/Orbit/2694/www.geocities.com/CapeCanaveral/Orbit/2694/

wlanl.htmwlanl.htm www.k12.hi.us.htmwww.k12.hi.us.htm www.proxim.comwww.proxim.com www.wirelesslan.comwww.wirelesslan.com www.www.wlanawlana.com.com

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