nagaraj seminar 09-05-11

8/2/2019 Nagaraj Seminar 09-05-11

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Contents

1. Introduction 03

2. What is Wi-Fi 05

3. Types of Wi-Fi Network

3.1Internet access

3.1.1 City-wide Wi-Fi

3.1.2 Campus-wide Wi-Fi

3.1.3 Long Distance Wi-Fi

4 . Hardware 09

4.1Standard devices

4.2 Distance records

4.3 Embedded systems

5 . Network Security 11

5.1 Securing methods

5.2 Piggybacking

6. Smart Antennas 14

6.1 Direction of arrival (DOA) estimation

6.2 Beamforming

6.3 Types of Smart Antennas

6.4 What is a Smart Antenna?

7. Smart Antenna Chip enhances Wi-Fi range, Speed 18

8. Health Issues 19

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http://en.wikipedia.org/wiki/Wifi#The_name_Wi-Fihttp://en.wikipedia.org/wiki/Wifi#Internet_accesshttp://en.wikipedia.org/wiki/Wifi#City-wide_Wi-Fihttp://en.wikipedia.org/wiki/Wifi#Campus-wide_Wi-Fihttp://en.wikipedia.org/wiki/Wifi#Hardwarehttp://en.wikipedia.org/wiki/Wifi#Standard_deviceshttp://en.wikipedia.org/wiki/Wifi#Distance_recordshttp://en.wikipedia.org/wiki/Wifi#Embedded_systemshttp://en.wikipedia.org/wiki/Wifi#Network_securityhttp://en.wikipedia.org/wiki/Wifi#Securing_methodshttp://en.wikipedia.org/wiki/Wifi#Piggybackinghttp://en.wikipedia.org/wiki/Wifi#Health_Issueshttp://en.wikipedia.org/wiki/Wifi#The_name_Wi-Fihttp://en.wikipedia.org/wiki/Wifi#Internet_accesshttp://en.wikipedia.org/wiki/Wifi#City-wide_Wi-Fihttp://en.wikipedia.org/wiki/Wifi#Campus-wide_Wi-Fihttp://en.wikipedia.org/wiki/Wifi#Hardwarehttp://en.wikipedia.org/wiki/Wifi#Standard_deviceshttp://en.wikipedia.org/wiki/Wifi#Distance_recordshttp://en.wikipedia.org/wiki/Wifi#Embedded_systemshttp://en.wikipedia.org/wiki/Wifi#Network_securityhttp://en.wikipedia.org/wiki/Wifi#Securing_methodshttp://en.wikipedia.org/wiki/Wifi#Piggybackinghttp://en.wikipedia.org/wiki/Wifi#Health_Issues


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9. Advantages and Challenges 20

9.1 Operational advantages

9.2 Limitations

9.3 Reach

9.4 Data security risks

10. Future Scope 2311. Conclusion 23

12. References 24

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Introduction

Wi-Fi is a trademark of the Wi-Fi Alliance. A Wi-Fi enabled device such as apersonal computer, video game console, smartphone, or digital audio playercan connect to the Internet when within range of a wireless networkconnected to the Internet. The coverage of one or more (interconnected)access points called hotspots when offering public access generallycomprises an area the size of a few rooms but may be expanded to covermany square miles, depending on the number of access points withoverlapping coverage.

'Wi-Fi' is not a technical term. However, the Alliance has generally enforcedits use to describe only a narrow range of connectivity technologies including

wireless local area network (WLAN) based on the IEEE 802.11 standards,device to device connectivity [such as Wi-Fi Peer to Peer AKA Wi-Fi Direct],and a range of technologies that support PAN, LAN and even WANconnections. Derivative terms, such as Super Wi-Fi, coined by the U.S.Federal Communications Commission (FCC) to describe proposednetworking in the former UHF TV band in the US, may or may not besanctioned by the alliance.As of November 2010 this was very unclear.

The technical term "IEEE 802.11" has been used interchangeably with Wi-Fi,but over the past few years Wi-Fi has become a superset of IEEE 802.11.Wi-Fi is used by over 700 million people, there are over 750,000 hotspots

(places with Wi-Fi Internet connectivity) around the world, and about 800million new Wi-Fi devices every year. Wi-Fi products that complete the Wi-FiAlliance interoperability certification testing successfully can use the Wi-FiCERTIFIED designation and trademark.

Not every Wi-Fi device is submitted for certification to the Wi-Fi Alliance. Thelack of Wi-Fi certification does not necessarily imply a device is incompatiblewith Wi-Fi devices/protocols. If it is compliant or partly compatible, the Wi-Fi

Alliance may not object to its description as a Wi-Fi device thoughtechnically only the CERTIFIED designation carries their approval.

Wi-Fi certified and compliant devices are installed in many personalcomputers, video game consoles, MP3 players, smartphones, printers,digital cameras, and laptop computers. However, the use of Wi-Fi via virtualRouter is also possible in a number of ways. Non-Wi-Fi-Alliance wirelesstechnologies intended for fixed points such as Motorola Canopy are usuallydescribed as fixed wireless. Non-Wi-Fi-Alliance wireless technologies

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http://en.wikipedia.org/wiki/Trademarkhttp://en.wikipedia.org/wiki/Wi-Fi_Alliancehttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Wireless_networkhttp://en.wikipedia.org/wiki/Wireless_access_pointhttp://en.wikipedia.org/wiki/Hotspot_(Wi-Fi)http://en.wikipedia.org/wiki/Wireless_LANhttp://en.wikipedia.org/wiki/IEEE_802.11http://en.wikipedia.org/wiki/Personal_area_networkhttp://en.wikipedia.org/wiki/Local_area_networkhttp://en.wikipedia.org/wiki/Wide_area_networkhttp://en.wikipedia.org/wiki/Super_Wi-Fihttp://en.wikipedia.org/wiki/Federal_Communications_Commissionhttp://en.wikipedia.org/wiki/IEEE_802.11http://en.wikipedia.org/wiki/Hotspot_(Wi-Fi)http://en.wikipedia.org/wiki/Personal_computerhttp://en.wikipedia.org/wiki/Personal_computerhttp://en.wikipedia.org/wiki/Video_game_consolehttp://en.wikipedia.org/wiki/MP3_playerhttp://en.wikipedia.org/wiki/Smartphonehttp://en.wikipedia.org/wiki/Printer_(computing)http://en.wikipedia.org/wiki/Digital_camerahttp://en.wikipedia.org/wiki/Laptophttp://en.wikipedia.org/wiki/Motorola_Canopyhttp://en.wikipedia.org/wiki/Fixed_wirelesshttp://en.wikipedia.org/wiki/Trademarkhttp://en.wikipedia.org/wiki/Wi-Fi_Alliancehttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Wireless_networkhttp://en.wikipedia.org/wiki/Wireless_access_pointhttp://en.wikipedia.org/wiki/Hotspot_(Wi-Fi)http://en.wikipedia.org/wiki/Wireless_LANhttp://en.wikipedia.org/wiki/IEEE_802.11http://en.wikipedia.org/wiki/Personal_area_networkhttp://en.wikipedia.org/wiki/Local_area_networkhttp://en.wikipedia.org/wiki/Wide_area_networkhttp://en.wikipedia.org/wiki/Super_Wi-Fihttp://en.wikipedia.org/wiki/Federal_Communications_Commissionhttp://en.wikipedia.org/wiki/IEEE_802.11http://en.wikipedia.org/wiki/Hotspot_(Wi-Fi)http://en.wikipedia.org/wiki/Personal_computerhttp://en.wikipedia.org/wiki/Personal_computerhttp://en.wikipedia.org/wiki/Video_game_consolehttp://en.wikipedia.org/wiki/MP3_playerhttp://en.wikipedia.org/wiki/Smartphonehttp://en.wikipedia.org/wiki/Printer_(computing)http://en.wikipedia.org/wiki/Digital_camerahttp://en.wikipedia.org/wiki/Laptophttp://en.wikipedia.org/wiki/Motorola_Canopyhttp://en.wikipedia.org/wiki/Fixed_wireless


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What is Wi-Fi ?

The term Wi-Fisuggests Wireless Fidelity, resembling the long-establishedaudio-equipment classification term high fidelity(in use since the 1930s) orHi-Fi (used since 1950). Even the Wi-Fi Alliance itself has often used thephrase Wireless Fidelity in its press releases and documents; the term alsoappears in a white paper on Wi-Fi from ITAA. The term Wi-Fi, first usedcommercially in August 1999, was coined by a brand-consulting firm calledInterbrand Corporation that the Alliance had hired to determine a name thatwas "a little catchier than 'IEEE 802.11b Direct Sequence'".

The Wi-Fi Alliance initially used an advertising slogan for Wi-Fi, "TheStandard for Wireless Fidelity", but later removed the phrase from theirmarketing. Despite this, some documents from the Alliance dated 2003 and2004 still contain the term Wireless Fidelity.

Types of Wi-Fi Network

1) City wide Wi-Fi

2) Campus wide Wi-Fi3) Long Distance Wi-Fi

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http://en.wikipedia.org/wiki/High_fidelityhttp://en.wikipedia.org/wiki/Information_Technology_Association_of_Americahttp://en.wikipedia.org/wiki/Interbrandhttp://en.wikipedia.org/wiki/Advertising_sloganhttp://en.wikipedia.org/wiki/High_fidelityhttp://en.wikipedia.org/wiki/Information_Technology_Association_of_Americahttp://en.wikipedia.org/wiki/Interbrandhttp://en.wikipedia.org/wiki/Advertising_slogan


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Internet access

Figure 2. A roof-mounted Wi-Fi antenna

A Wi-Fi enabled device such as a personal computer, video game console,smartphone or digital audio player can connect to the Internet when withinrange of a wireless network connected to the Internet. The coverage of oneor more (interconnected) access points called hotspots can comprisean area as small as a few rooms or as large as many square miles.

Coverage in the larger area may depend on a group of access points withoverlapping coverage. Wi-Fi technology has been used in wireless meshnetworks, for example, in London, UK.

In addition to private use in homes and offices, Wi-Fi can provide publicaccess at Wi-Fi hotspots provided either free-of-charge or to subscribers tovarious commercial services. Organizations and businesses - such as thoserunning airports, hotels and restaurants - often provide free-use hotspots toattract or assist clients. Enthusiasts or authorities who wish to provideservices or even to promote business in selected areas sometimes providefree Wi-Fi access. As of 2008 more than 300 metropolitan-wide Wi-Fi (Muni-

Fi) projects had started. As of 2010 the Czech Republic had 1150 Wi-Fibased wireless Internet service providers.

Routers that incorporate a digital subscriber line modem or a cable modemand a Wi-Fi access point, often set up in homes and other premises, canprovide Internet access and internetworking to all devices connected

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http://en.wikipedia.org/wiki/Personal_computerhttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Wireless_networkhttp://en.wikipedia.org/wiki/Wireless_access_pointhttp://en.wikipedia.org/wiki/Wireless_mesh_networkhttp://en.wikipedia.org/wiki/Wireless_mesh_networkhttp://en.wikipedia.org/wiki/Businesshttp://en.wikipedia.org/wiki/Municipal_wireless_networkhttp://en.wikipedia.org/wiki/Municipal_wireless_networkhttp://en.wikipedia.org/wiki/Czech_Republichttp://en.wikipedia.org/wiki/Wireless_Internet_service_providerhttp://en.wikipedia.org/wiki/Routerhttp://en.wikipedia.org/wiki/Digital_subscriber_linehttp://en.wikipedia.org/wiki/Cable_modemhttp://en.wikipedia.org/wiki/Internetworkinghttp://en.wikipedia.org/wiki/File:WIFI_Amp_Setup.JPGhttp://en.wikipedia.org/wiki/Personal_computerhttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Wireless_networkhttp://en.wikipedia.org/wiki/Wireless_access_pointhttp://en.wikipedia.org/wiki/Wireless_mesh_networkhttp://en.wikipedia.org/wiki/Wireless_mesh_networkhttp://en.wikipedia.org/wiki/Businesshttp://en.wikipedia.org/wiki/Municipal_wireless_networkhttp://en.wikipedia.org/wiki/Municipal_wireless_networkhttp://en.wikipedia.org/wiki/Czech_Republichttp://en.wikipedia.org/wiki/Wireless_Internet_service_providerhttp://en.wikipedia.org/wiki/Routerhttp://en.wikipedia.org/wiki/Digital_subscriber_linehttp://en.wikipedia.org/wiki/Cable_modemhttp://en.wikipedia.org/wiki/Internetworking


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(wirelessly or by cable) to them. With the emergence of MiFi and WiBro (aportable Wi-Fi router) people can easily create their own Wi-Fi hotspots thatconnect to Internet via cellular networks. Now iPhone,Android, and Symbianphones can create wireless connections.

One can also connect Wi-Fi devices in ad-hoc mode for client-to-clientconnections without a router. Wi-Fi also connects places that wouldtraditionally not have network access, for example kitchens and gardensheds.

City-wide Wi-Fi

Figure 3. An outdoor Wi-Fi access point in Minneapolis

In the early 2000s, many cities around the world announced plans for city-wide Wi-Fi networks. This proved to be much more difficult than theirpromoters initially envisioned with the result that most of these projects wereeither canceled or placed on indefinite hold. A few were successful, for

example in 2005, Sunnyvale, California became the first city in the UnitedStates to offer city-wide free Wi-Fi, and Minneapolis has generated $1.2million profit annually for their provider. In May, 2010, London, UK MayorBoris Johnson pledged London-wide Wi-Fi by 2012.

Campus-wide Wi-Fi

Carnegie Mellon University built the first wireless Internet network in theworld at their Pittsburgh campus in 1994, long before Wi-Fi brandingoriginated in 1999. Many traditional college campuses provide at least partialwireless Wi-Fi Internet coverage.

Drexel University in Philadelphia made history by becoming the UnitedStates' first major university to offer completely wireless Internet accessacross the entire campus in 2000.

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http://en.wikipedia.org/wiki/MiFihttp://en.wikipedia.org/wiki/WiBrohttp://en.wikipedia.org/wiki/Cellular_networkhttp://en.wikipedia.org/wiki/IPhonehttp://en.wikipedia.org/wiki/Android_(operating_system)http://en.wikipedia.org/wiki/Symbianhttp://en.wikipedia.org/wiki/Wireless_ad_hoc_networkhttp://en.wikipedia.org/wiki/Sunnyvale,_Californiahttp://en.wikipedia.org/wiki/Minneapolishttp://en.wikipedia.org/wiki/Carnegie_Mellon_Universityhttp://en.wikipedia.org/wiki/Pittsburghhttp://en.wikipedia.org/wiki/Drexel_Universityhttp://en.wikipedia.org/wiki/File:Metro_Wireless_Node.jpghttp://en.wikipedia.org/wiki/MiFihttp://en.wikipedia.org/wiki/WiBrohttp://en.wikipedia.org/wiki/Cellular_networkhttp://en.wikipedia.org/wiki/IPhonehttp://en.wikipedia.org/wiki/Android_(operating_system)http://en.wikipedia.org/wiki/Symbianhttp://en.wikipedia.org/wiki/Wireless_ad_hoc_networkhttp://en.wikipedia.org/wiki/Sunnyvale,_Californiahttp://en.wikipedia.org/wiki/Minneapolishttp://en.wikipedia.org/wiki/Carnegie_Mellon_Universityhttp://en.wikipedia.org/wiki/Pittsburghhttp://en.wikipedia.org/wiki/Drexel_University


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locally installed and supported and meet the organizations operationalneeds.

Key features include:

Rugged wireless routers that can be used in multiple network configurations,for long-distance point-to-point links or to connect multiple locations

Access points that require very little network and device setup, withintegrated software that has an internal webserver with easy-to-useinterface accessible from any standard web browser

Designed for the harshest environments with waterproofed and ruggedizedcases, a waterproof sealed RJ-45 connectors

Configurable with one or two radios and choices of antennas for a variety ofnetwork configurations including patch, 24dBi dish, or omni

Lightning protection

Key hardware design features include:

Network connectivity links from 1km up to 100km One or two WiFi radio for use as point-to-point, point-to-multipoint WLAN or

relay station Includes Power-Over-Ethernet injector, pole-mounting kit, and choice of

patch, 24dBi dish, or omni antenna Operable from 12 VDC (110/240 VAC adaptor also available) Network auto-sensing device for faster set-up Rugged, waterproof enclosure.

Hardware

Standard devices

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Figure 5. Hardware Interface

An embedded RouterBoard 112 with U.FL-RSMA pigtail and R52 mini PCI Wi-Ficard widely used by wireless Internet service providers (WISPs) in the CzechRepublic

Figure 6. Wi-Fi Antenna

OSBRiDGE 3GN - 802.11n Access Point and UMTS/GSM Gateway in one device

Figure 7. Wireless USB adapter

A wireless access point (WAP) connects a group of wireless devices to anadjacent wired LAN. An access point resembles a network hub, relayingdata between connected wireless devices in addition to a (usually) singleconnected wired device, most often an ethernet hub or switch, allowingwireless devices to communicate with other wired devices.

Wireless adapters allow devices to connect to a wireless network. Theseadapters connect to devices using various external or internal interconnectssuch as PCI, miniPCI, USB, ExpressCard, Cardbus and PC Card. As of

2010, most newer laptop computers come equipped with internal adapters.Internal cards are generally more difficult to install.

Wireless routers integrate a Wireless Access Point, ethernet switch, andinternal router firmware application that provides IProuting, NAT, and DNSforwarding through an integrated WAN-interface. A wireless router allows

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http://en.wikipedia.org/wiki/Embedded_systemhttp://en.wikipedia.org/wiki/Hirose_U.FLhttp://en.wikipedia.org/wiki/SMA_connectorhttp://en.wikipedia.org/wiki/Conventional_PCIhttp://en.wikipedia.org/wiki/Wirelesshttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Wireless_Internet_service_providerhttp://en.wikipedia.org/wiki/Czech_Republichttp://en.wikipedia.org/wiki/Czech_Republichttp://en.wikipedia.org/wiki/IEEE_802.11n-2009http://en.wikipedia.org/wiki/High-Speed_Downlink_Packet_Accesshttp://en.wikipedia.org/wiki/Wireless_access_pointhttp://en.wikipedia.org/wiki/Local_area_networkhttp://en.wikipedia.org/wiki/Ethernet_hubhttp://en.wikipedia.org/wiki/Data_(computing)http://en.wikipedia.org/wiki/Wireless_network_interface_controllerhttp://en.wikipedia.org/wiki/Conventional_PCIhttp://en.wikipedia.org/wiki/Conventional_PCIhttp://en.wikipedia.org/wiki/Universal_Serial_Bushttp://en.wikipedia.org/wiki/ExpressCardhttp://en.wikipedia.org/wiki/PC_Cardhttp://en.wikipedia.org/wiki/Wireless_routerhttp://en.wikipedia.org/wiki/Network_switchhttp://en.wikipedia.org/wiki/Internet_Protocolhttp://en.wikipedia.org/wiki/Routinghttp://en.wikipedia.org/wiki/Network_address_translationhttp://en.wikipedia.org/wiki/Domain_Name_Systemhttp://en.wikipedia.org/wiki/Wide_area_networkhttp://en.wikipedia.org/wiki/File:Wireless_adaptor_USB.jpghttp://en.wikipedia.org/wiki/File:3GN_.jpghttp://en.wikipedia.org/wiki/Embedded_systemhttp://en.wikipedia.org/wiki/Hirose_U.FLhttp://en.wikipedia.org/wiki/SMA_connectorhttp://en.wikipedia.org/wiki/Conventional_PCIhttp://en.wikipedia.org/wiki/Wirelesshttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Wireless_Internet_service_providerhttp://en.wikipedia.org/wiki/Czech_Republichttp://en.wikipedia.org/wiki/Czech_Republichttp://en.wikipedia.org/wiki/IEEE_802.11n-2009http://en.wikipedia.org/wiki/High-Speed_Downlink_Packet_Accesshttp://en.wikipedia.org/wiki/Wireless_access_pointhttp://en.wikipedia.org/wiki/Local_area_networkhttp://en.wikipedia.org/wiki/Ethernet_hubhttp://en.wikipedia.org/wiki/Data_(computing)http://en.wikipedia.org/wiki/Wireless_network_interface_controllerhttp://en.wikipedia.org/wiki/Conventional_PCIhttp://en.wikipedia.org/wiki/Conventional_PCIhttp://en.wikipedia.org/wiki/Universal_Serial_Bushttp://en.wikipedia.org/wiki/ExpressCardhttp://en.wikipedia.org/wiki/PC_Cardhttp://en.wikipedia.org/wiki/Wireless_routerhttp://en.wikipedia.org/wiki/Network_switchhttp://en.wikipedia.org/wiki/Internet_Protocolhttp://en.wikipedia.org/wiki/Routinghttp://en.wikipedia.org/wiki/Network_address_translationhttp://en.wikipedia.org/wiki/Domain_Name_Systemhttp://en.wikipedia.org/wiki/Wide_area_network


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wired and wireless ethernet LAN devices to connect to a (usually) singleWAN device such as a cable modem or a DSL modem. A wireless routerallows all three devices, mainly the access point and router, to be configuredthrough one central utility. This utility is usually an integrated web serverthatis accessible to wired and wireless LAN clients and often optionally to WAN

clients. This utility may also be an application that is run on a desktopcomputer such as Apple'sAirPort.

Wireless network bridges connect a wired network to a wireless network. Abridge differs from an access point: an access point connects wirelessdevices to a wired network at the data-link layer. Two wireless bridges maybe used to connect two wired networks over a wireless link, useful insituations where a wired connection may be unavailable, such as betweentwo separate homes.

Wireless range-extenders or wireless repeaters can extend the range of an

existing wireless network. Strategically placed range-extenders can elongatea signal area or allow for the signal area to reach around barriers such asthose pertaining in L-shaped corridors. Wireless devices connected throughrepeaters will suffer from an increased latency for each hop. Additionally, awireless device connected to any of the repeaters in the chain will have athroughput limited by the "weakest link" between the two nodes in the chainfrom which the connection originates to where the connection ends.

Distance records

Distance records (using non-standard devices) include 382 km (237 mi) in

June 2007, held by Ermanno Pietrosemoli and EsLaRed of Venezuela,transferring about 3 MB of data between the mountain-tops of El guila andPlatillon. The Swedish Space Agency transferred data 420 km (260 mi),using 6 watt amplifiers to reach an overhead stratospheric balloon.

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Embedded Systems

Figure 8.Embedded serial-to-Wi-Fi module

Increasingly in the last few years (particularly as of 2007), embedded Wi-Fimodules have become available that incorporate a real-time operatingsystem and provide a simple means of wirelessly enabling any device whichhas and communicates via a serial port. This allows the design of simplemonitoring devices. An example is a portable ECG device monitoring apatient at home. This Wi-Fi-enabled device can communicate via theInternet.

These Wi-Fi modules are designed so that implementers need only minimalWi-Fi knowledge to provide Wi-Fi connectivity for their products.

Network security

The main issue with wireless network security is its simplified access to thenetwork compared to traditional wired networks such as ethernet. With wirednetworking one must either gain access to a building (physically connectinginto the internal network) or break through an external firewall. Mostbusiness networks protect sensitive data and systems by attempting todisallow external access. Enabling wireless connectivity provides an attackvector, particularly if the network uses inadequate or no encryption.

An attacker who has gained access to a Wi-Fi network router can initiate a

DNS spoofing attack against any other user of the network by forging aresponse before the queried DNS server has a chance to reply.

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Securing methods

A common but unproductive measure to deter unauthorized users involvessuppressing the access point's SSID broadcast. This is ineffective as asecurity method because the SSID is broadcast in the clear in response to a

client SSID query. Another unproductive method is to only allow computerswith known MAC addresses to join the network. But, intruders can defeatthis method because they can often (though not always) set MAC addresseswith minimal effort (MAC spoofing). If eavesdroppers have the ability tochange their MAC address, then they may join the network by spoofing anauthorized address.

Wired Equivalent Privacy (WEP) encryption was designed to protect againstcasual snooping, but is now deprecated. Tools such as AirSnort orAircrack-ng can quickly recover WEP encryption keys. Once it has seen 5-10 millionencrypted packets, AirSnort can determine the encryption password in under

a second; newer tools such as aircrack-ptw can use Klein's attack to crack aWEP key with a 50% success rate using only 40,000 packets.

To counteract this in 2002, the Wi-Fi Alliance approved Wi-Fi ProtectedAccess (WPA) which uses TKIP as a stopgap solution for legacy equipment.Though more secure than WEP, it has outlived its designed lifetime and hasknown attack vectors.

In 2004, the IEEE ratified the full IEEE 802.11i (WPA2) encryptionstandards. If used with a 802.1X server or in pre-shared key mode with astrong and uncommon passphrase WPA2 is still considered secure by many

IT professionals.Piggybacking (Internet access)

Piggybacking refers to access to a wireless Internet connection by bringingone's own computer within the range of another's wireless connection, andusing that service without the subscriber's explicit permission or knowledge.

During the early popular adoption of 802.11, providing open access pointsfor anyone within range to use was encouraged to cultivate wirelesscommunity networks, particularly since people on average use only a

fraction of their downstream bandwidth at any given time.Recreational logging and mapping of other people's access points hasbecome known as wardriving. Indeed, many access points are intentionallyinstalled without security turned on so that they can be used as a freeservice. Providing access to one's Internet connection in this fashion may

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Smart Antennas

Smart Antennas (also known as adaptive array antennas, multipleantennas and recently MIMO) are antenna arrays with smart signalprocessing algorithms used to identify spatial signal signature such as thedirection of arrival (DOA) of the signal, and use it to calculate beamformingvectors, to track and locate the antenna beam on the mobile/target. Theantenna could optionally be any sensor.

Smart antenna techniques are used notably in acoustic signal processing,track and scan RADAR,radio astronomy and radio telescopes, and mostly incellular systems like W-CDMA and UMTS.

Smart antennas have two main functions:

1) DOA Estimation and2) Beamforming.

Direction of arrival (DOA) estimation

The smart antenna system estimates the direction of arrival of the signal,using techniques such as MUSIC (Multiple Signal Classification), estimationof signal parameters via rotational invariance techniques (ESPRIT)algorithms, Matrix Pencil method or one of their derivatives. They involvefinding a spatial spectrum of the antenna/sensor array, and calculating theDOA from the peaks of this spectrum. These calculations arecomputationally intensive.

Matrix Pencil is very efficient in case of real time systems, and under thecorrelated sources.

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Beamforming

Beamforming is the method used to create the radiation pattern of theantenna array by adding constructively the phases of the signals in thedirection of the targets/mobiles desired, and nulling the pattern of the

targets/mobiles that are undesired/interfering targets. This can be done witha simple FIR tapped delay line filter. The weights of the FIR filter may alsobe changed adaptively, and used to provide optimal beamforming, in thesense that it reduces the MMSE between the desired and actualbeampattern formed. Typical algorithms are the steepest descent, and LMSalgorithms.

Types of smart antennas

Two of the main types of smart antennas include:

1) Switched Beam Smart Antennas and2) Adaptive Array Smart Antennas.

Switched beam systems have several available fixed beam patterns.Adecision is made as to which beam to access, at any given point in time,based upon the requirements of the system.

Adaptive arrays allow the antenna to steer the beam to any direction ofinterest while simultaneously nulling interfering signals. Beamdirection canbe estimated using the so-called direction-of-arrival (DOA) estimationmethods.

With wireless LAN optimism rolling freely, smart antenna startups arecontinuing to pop up.

Four of the newer players presented their cases at a panel session in aweek's Wi-Fi Planet conference, all of them emphasizing the effect a smartantenna can have on range.

What is a Smart Antenna?

Most antennas just send signals out in all directions; "smart" ones adjusttheir power and resources depending on the position of the user or obstaclesin the area.

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Smart antennas aren't new. Companies likeArrayComm Inc. are sellingthem into the cellular world. But lately, antenna startups are targeting thewireless LAN industry. Multiple-antenna schemes are being used by firmssuch asAirgo Networks and Vivato Inc. to increase wireless LANperformance, for example.

With range being more of an issue than speed on WLAN networks, smartantenna technology could boost the ability of network designers to reducecosts by improving the area covered by each access point.

The technologies could also help wireless ISPs (WISPs) reach moresubscribers cheaply, an important point considering the difficulty they've hadmaking money. "WISPs go bigger and bigger to reach more customers, butthey never see the profit/loss margin they need," says Jack Nilsson, chiefscientist ofWi-Fi-Plus Inc.

Smart antennas come in a dizzying variety of approaches. The fourpioneering companies in field of Wi-Fi are as follows:

Bandspeed Inc. disclosed its Gypsy antenna in April. Gypsy uses adirectional approach, making antennas more efficient by narrowingtheir focus. The system splits the 360-degree universe into six 60-degree sectors, with antennas tracking each sector rather than a fullcircle. Customers using Bandspeed's technology are expected to shipat the end of next quarter.

Motiauses analog processing techniques to derive four signals froman 802.11 transmission. It uses a weighted combination of the four todetermine where the sender was, then uses the same set of weightsto transmit signals back. The process gets repeated for every packet,so the antenna can track a moving user. Antennas using thetechnology should be available next year.

Wi-Fi Plus exploits polarization to grab signals thrown away by otherantennas. It's polarization that causes signals to weaken as theyreflect off walls or pass through objects, Wi-Fi Plus's founders say.The company's antenna is designed to pick up those polarized

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signals. Wi-Fi Plus is shipping antennas but would like to get itsproduct embedded into other companies' cards.

ZeeWaves Systems Inc.is another advocate of the directionalapproach. The company's antenna can broadcast in 360 degress as anormal antenna does, but it can also narrow the angle to as little as10 degrees. ZeeWaves' products are in beta trials.

Not everybody believes 802.11 needs a range boost. Companies such asTropos Networks, for example, are using short-reach 802.11 cells meshedtogether to create better coverage. And switch startup Aruba WirelessNetworks thinks access points should stay dumb and cheap, so that ifparticular users are out of range, it's affordable to just install an extra AP forthem.

The cost question presents a barrier to the smart antenna crowd when itcomes to wireless LANs, says Jack Winters, chief scientist for Motia. "Chipvendors and AP vendors are very reluctant to put a 'Super AP' on the shelfthat's 30 percent more expensive than everything else."

To counter that problem, smart antenna vendors might want to emphasizethat they supposedly can cut the number of access points needed. "Theymight spend $100 on the antenna but find they save $1,000 on the APs,"says Khurshid Qureshi, CEO of ZeeWaves.

Another challege is that more players continue to join the field, such asstealthy Wavion Inc., which is developing some kind of outdoor antenna(although it might not be targeted at wireless LANs). The firm picked up $6million earlier this year, a round that was extended to $12.5 million inOctober, according to the most recent quarterly filing from lead investorElron Electric Industries Ltd. (Nasdaq: ELRN).

How smart antennas could boost WiFi performance ?

We've all had the problem of going into a crowded Starbucks and sufferingthrough a substandard Wi-Fi signal, most likely caused by too few access

points and too many end users.

But what if Wi-Fi antennas could do a better job of detecting how manydevices were in a given room and could push data out to them more rapidlyon a one-by-one basis? That's what researchers at Gonzaga University aretrying to accomplish by testing "smart antenna" technology in their new

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research lab that just received a federal research grant worth nearly $1.2million from the American National Science Foundation.

What problem is research in wireless technology trying to address?

The problem is interference. Right now the airspace is full of lots of peopletrying to communicate over the 2.4GHz band, which is used for Wi-Fi. Ourgoal is to design a smart antenna that can zero in on a desired signal andreject the others. We're designing software-defined radios that work with theaccess-point antennas to optimise the signal-to-noise ratio.

So the software will try to optimise the transmission between your computerand the access point wherever it is while also minimising what you'rereceiving from other computers. The access point would focus itself on oneradio at a time. Access points are typically "dumb" in that they radiate somepower in all directions at once. So when one computer has a weaker signal

or different polarisation, a smart antenna could adjust the polarisation andwould form a beam directly to the laptop it wanted to talk to.

Wouldn't this necessarily degrade the quality of signal being sent toother laptops in the area?

The access point would do this very quickly, and actually it would take lesstime dealing with each radio one at a time than trying to push out data tothem all at once. It'll be far less likely that you'll have to retransmit somethingor have a frame error in your transmission if you do it this way.

This isn't a unique setup by any means but it is expensive to set up and a lotof companies don't have this capability. So if they have a product they wantto test they can come to our place and do it here. We can even give them anidea of what they might have to do to get their product to meet FCCguidelines.

Smart Antenna Chip enhances Wi-Fi range,speed

A good antenna is the most important thing to get a microwave radio

performance. It is the integral part of the system though manufacturers see itas a necessary evil. Today, the approach has changed a lot with thedesigners paying more and more attention to the antenna. Smart antennassettle in existing environment and the function and transmission of thesystem gets optimized. This is actually a new piece of equipment in theirportfolio.

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In that stratum, the Javelin chip from semiconductor company Motiaimplements these antennas forWi-Fi products. This device is grouped withof an array of four antennas. It can widen the range of any 802.11b/gtransceiver by four times at most. It can also develop the entire systemperformance as well as quality of service of the Wi-Fi product.

Generally, Wi-Fi products offer coverage up to 100 meters (over 300 feet).But barriers like walls, floors and ceilings can shorten this range. Reflectionsfrom multiple objects and other obstacles can also shorten the range. Moreover, as the range is inadequate, connectivity speed mechanically drops assignal quality depreciates.

To get rid of this problem, the Javelin is placed between the four-antennaarray and the input is given to the wi-fi transceiver chip. The chip uses anappliqu architecture that allows the technology to be used in any accesspoint or client widget.

The Javelin actually outfits an array of four antennas which is similar to thetwo antenna range configurations which are now generally used on someaccess points. Through the receive mode, the signals at each antenna areconverted to a received-signal strength indicator (RSSI) value. The RSSI isthen evaluated and then grouped to bring out the strongest doable output tothe amplifier of the Wi-Fi chip set. In case you are unable to understandthere are various online PC support companies that help you to do thesame.

In the broadcast mode, the signal from the transceiver is separated in foursegments. Each of those signals is transferred and amplified by the profiledistinct by the received signal before being transmitted. This results in a 13-dB increase over a single antenna. The overall gain mounts up to 18 dB asthe javelin is used at both ends of the system.

This fully analog device is compatible with both 802.11b and 802.11gsystems and can work with any Wi-Fi product.

Health Issues

A small percentage of Wifi users have reported adverse health issues afterrepeat exposure and use of Wifi.

Common ailments of "Wifi Sickness" or "Wifi Sensitivity" as described bythose who have suffered include "unusual headaches as well as one ormore of the following symptoms: nausea, heart irregularities and "racing

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heart" rates, temporary incidents of loss of balance and dizziness, chestpain, a heating and/or tingling sensation in the face area, undue physicalstress, panic attacks and/or mental anxiety, and minor cognitive impairment.

A few health experts conclude there is a strong neurological component todescribed health issues.

Concerns brought up by those who have been affected include thatadditional research is needed, that includes focus on whether only a certainsegment of the population is adversely affected by Wifi and RF technology,or if there is a larger underlying issue that ultimately could have adverse longterm health effects on the general population as a result of the constant andrepeat exposure to Wi-Fi that has recently become common throughoutmany industrialized nations.

Gro Harlem Brundtland, former Prime Minister of Norway and a medicaldoctor, certainly may be the most high profile case of someone who has

suffered from such conditions, and who has actively called on increaseawareness within the medical community.

The World Health Organization(WHO) and the United Kingdom's HealthProtection Agency report that there are no long term effects of EHSnotingthat exposure to Wi-Fi for a year results in "same amount of radiation from a20-minute mobile phone call."

Advantages and Challenges

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Figure 9. A keychain-size Wi-Fi detector

Operational advantages

Wi-Fi allows the deployment of local area networks (LANs) without wires for

client devices, typically reducing the costs of network deployment andexpansion. Spaces where cables cannot be run, such as outdoor areas andhistorical buildings, can host wireless LANs.

As of 2010 manufacturers are building wireless network adapters into mostlaptops. The price of chipsets for Wi-Fi continues to drop, making it aneconomical networking option included in even more devices. Wi-Fi hasbecome widespread in corporate infrastructures.

Different competitive brands of access points and client network-interfacescan inter-operate at a basic level of service. Products designated as "Wi-Fi

Certified" by the Wi-Fi Alliance are backwards compatible. "Wi-Fi"designates a globally operative set of standards: unlike mobile phones, anystandard Wi-Fi device will work anywhere in the world.

Wi-Fi operates in more than 220,000 public hotspots and in tens of millionsof homes and corporate and university campuses worldwide. The currentversion of Wi-Fi Protected Access encryption (WPA2) as of 2010 isconsidered secure, provided users employ a strong passphrase. Newprotocols forquality-of-service (WMM) make Wi-Fi more suitable for latency-sensitive applications (such as voice and video); and power savingmechanisms (WMM Power Save) improve battery operation.

Limitations

Spectrum assignments and operational limitations are not consistentworldwide: most of Europe allows for an additional two channels beyondthose permitted in the U.S. for the 2.4 GHz band (113 vs. 111), whileJapan has one more on top of that (114). Europe, as of 2007, wasessentially homogeneous in this respect. Note that: Wi-Fi cannot be used inItaly without a licence, and in both Italy and France, both ends of the Wi-Filink must be within the same building (i.e. a Wi-Fi active device cannot beused out of doors).

A Wi-Fi signal occupies five channels in the 2.4 GHz band; any two channelswhose channel numbers differ by five or more, such as 2 and 7, do notoverlap. The oft-repeated adage that channels 1, 6, and 11 are the onlynon-overlapping channels is, therefore, not accurate; channels 1, 6, and 11 do,however, comprise the only group of three non-overlapping channels in theU.S.

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Equivalent isotropically radiated power(EIRP) in the EU is limited to 20 dBm(100 mW).

The current 'fastest' norm 802.11n uses double the radio spectrumcompared to 802.11a or 802.11g. This means there can only be one

802.11n network on 2.4 GHz band without interference to other WLANtraffic, or none, if there already is an AP on any of the mid channels.

The on-coming 802.11ac will jam all the current WLAN bands, if allowed onsame bands. There might be a chance the 802.11ac would be allocated anew band, perhaps on UHF TV white space.

The Internet protocol performs poorly in the face of noise when run with WiFias the physical layer TCP has been tuned for a wired network in whichpackets lost due to noise is very rare and packets are lost almost exclusivelydue to congestion. On a wireless network, noise is common. This difference

causes TCP to greatly slow or break transmission when noise is significant,even when most packets are still arriving correctly.

Reach

Wi-Fi networks have limited range. A typical wireless routerusing 802.11b or802.11g with a stock antenna might have a range of 32 m (120 ft) indoorsand 95 m (300 ft) outdoors. The IEEE 802.11n however, can exceed thatrange by more than two times. Range also varies with frequency band. Wi-Fiin the 2.4 GHz frequency block has slightly better range than Wi-Fi in the5 GHz frequency block. Outdoor ranges - through use of directional

antennas - can be improved with antennas located several kilometres ormore from their base. In general, the maximum amount of power that a Wi-Fidevice can transmit is limited by local regulations, such as FCC Part 15 inUSA.

Due to reach requirements for wireless LAN applications, Wi-Fi has fairlyhigh power consumption compared to some other standards. Technologiessuch as Bluetooth (designed to support wireless PAN applications) provide amuch shorter propagation range of 10m and so in general have a lowerpower consumption. Other low-power technologies such as ZigBee havefairly long range, but much lower data rate. The high power consumption of

Wi-Fi makes battery life in mobile devices a concern.Researchers have developed a number of "no new wires" technologies toprovide alternatives to Wi-Fi for applications in which Wi-Fi's indoor range isnot adequate and where installing new wires (such as CAT-5) is not possibleor cost-effective. For example, the ITU-TG.hn standard for high speed Localarea networks uses existing home wiring (coaxial cables, phone lines and

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power lines). Although G.hn does not provide some of the advantages of Wi-Fi (such as mobility or outdoor use), it's designed for applications (such asIPTV distribution) where indoor range is more important than mobility.

Due to the complex nature ofradio propagation at typical Wi-Fi frequencies,

particularly the effects of signal reflection off trees and buildings, algorithmscan only approximately predict Wi-Fi signal strength for any given area inrelation to a transmitter. This effect does not apply equally to long-range Wi-Fi, since longer links typically operate from towers that broadcast above thesurrounding foliage.

Data security risks

The most common wireless encryption-standard, Wired Equivalent Privacy(WEP), has been shown to be easily breakable even when correctlyconfigured. Wi-Fi Protected Access (WPA and WPA2) encryption, which

became available in devices in 2003, aimed to solve this problem. Wi-Fiaccess points typically default to an encryption-free (open) mode. Noviceusers benefit from a zero-configuration device that works out-of-the-box, butthis default does not enable any wireless security, providing open wirelessaccess to a LAN. To turn security on requires the user to configure thedevice, usually via a software graphical user interface (GUI). Onunencrypted Wi-Fi networks connecting devices can monitor and record data(including personal information), but such networks may use other means ofprotection, such as a VPN or secure Hypertext Transfer Protocol (HTTPS)overTransport Layer Security.

Future Scope

As of 2010 Wi-Fi technology has spread widely within business andindustrial sites. In business environments, just like other environments,increasing the number of Wi-Fi access points provides network redundancy,support for fast roaming and increased overall network-capacity by usingmore channels or by defining smaller cells. Wi-Fi enables wireless voice-

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applications (VoWLAN or WVOIP). Over the years, Wi-Fi implementationshave moved toward "thin" access points, with more of the networkintelligence housed in a centralized network appliance, relegating individualaccess points to the role of "dumb" transceivers. Outdoor applications mayutilize mesh topologies.

Conclusion

Wi-Fi network promises to redefine wireless networking, finally bringing theall-wireless enterprise within reach. But Wi-Fi comes with ambiguity, highcost. But in coming years the innovation hunger industry may bring down thecost of technology & its production.

While vendors advertise data rates exceeding 300Mbps, the user experience

is quite different. The key to obtaining the promised performance of Wi-Finetwork system lies in the ability to take advantage of the new Wi-Fi networktechniques such as spatial multiplexing, channel bonding, frame aggregationand block acknowledgement. To do this, it is imperative to have visibility intoand control over the RF domain as well as to adapt to real-timeenvironmental changes that can negatively affect performance.

The vast majority of todays Wi-Fi network systems fail to provide adequateRF controls and adaptability, resulting in inconsistent system and sessionthroughputs. These systems must be tuned and retuned manually - requiringintimate knowledge of signal propagation characteristics and environmental

conditions.Smart Wi-Fi technology, however, solves critical complexity, reliability andperformance issues that surround Wi-Fi network. By automatically controllingWi-Fi signal path selection, Smart Wi-Fi systems are able to ensure thehighest likelihood that spatial multiplexing, channel bonding, frameaggregation and block acknowledgement will occur.

In addition, these Smart Wi-Fi systems are able to avoid and rejectinterference which handicaps Wi-Fi network performance and reliability.

The result is consistent and higher performing connections for more users at

any given range.

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nagaraj seminar 09-05-11

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