Wi-fi Overview 24092007 Dcs

Wi-Fi Overview

(Wireless Fidelity) By D C Sonkhla SDE(Comp) BRBRAITT, Jabalpur

Wi-Fi Overview (Wireless Fidelity)

1. 2. 3. 4. 5. 6.

Introduction & History of WiFi Access Point Hotspots Hotspots Security Advantages of Wi Fi Limitations of Wi Fi

brbraitt/dcsonkhla

Introduction & History Precursor to Wi-Fi was invented in 1991 by NCR Corporation / AT&T (Later Lucent & Agere Systems) in Nieuwgein, Netherlands.  The first wireless product was brought as WaveLAN with speed 1 / 2 MBPS.  Primary inventor of Wi-Fi was Vic Hayes called father of Wi-Fi.  He was also involved in designing standards for 802.11b / a / g. 

brbraitt/dcsonkhla

Introduction & History 

Interbrand developed the logo “Wi-Fi” (Otherwise IEEE802.11 Direct Sequence) for Wi-Fi Ethernet Compatibility Alliances)



Wi-Fi Logo indicates that the product is certified for interoperability by Wi-Fi Alliances.

brbraitt/dcsonkhla

Introduction & History In 1985 Federal Communications Commissions made available Unlicense Spread Spectrum enabling the use of this technology in all major countries. This proposal was to allow civic use of Spread Spectrum technology. Wi-Fi uses single carrier direct sequence Spread Spectrum radio technology and Multi Carrier OFDM(Orthogonal Frequency Division Multiplexing) radio technology. brbraitt/dcsonkhla

Introduction & History 



 

A person with Wi-Fi enabled device such as computer, cell-phone etc can connect to the internet when in the proximity of an Access Point. The region covered by one or more Access Point is called a Hotspot. Hotspots can range from a single room to many square miles of overlapping hotspots. Wi-Fi can also be used to create a mesh network. Wi-Fi allows connectivity in peer-to-peer (wireless adhoc network) mode. brbraitt/dcsonkhla

Introduction & History 



It provides the final few metres of connectivity between a wired network and the mobile user thereby providing mobility, scalability of networks and the speed of installation. WIFI is a wireless LAN Technology to deliver wireless broad band speeds up to 54 Mbps to Laptops, PCs, PDAs , dual mode wifi enabled phones etc. Apart from Data delivery Voice over WIFI is also in pipeline. brbraitt/dcsonkhla

Access Point 



A Wireless Access Point(WAP) or Access Point(AP) is a device that connects wireless communication devices together to form a wireless network. It is usually connected to a wired network and can relay data between wireless & wired devises. Several WAPs can link together to form a larger network that allows “roaming”. WAP has an IP address for configuration. brbraitt/dcsonkhla

Access Point 





WAPs grew rapidally in 2000 as easily installable devices. Mess of cables on wall, ceilings could be reduced or eliminated completely. They offered greater mobility enabling employees to carry portable data terminals integrating barcode scanners and wireless links for updates in real time.

brbraitt/dcsonkhla

Access Point

A typical Wi-Fi Network brbraitt/dcsonkhla

Access Point 



Like a cellular phone system, the wireless LAN is capable of roaming from the AP and re-connecting to the network through other APs residing at other points on the wired network. This can allow the wired LAN to be extended to cover a much larger area than the existing coverage by the use of multiple APs such as in a campus environment as shown in Fig-2.

brbraitt/dcsonkhla

Access Point

Extending Wi-Fi coverage with multiple APs brbraitt/dcsonkhla

Access Point Wireless LAN  An important feature of the wireless LAN is that it can be used independent of a wired network.  It may be used as a stand alone network anywhere to link multiple computers together without having to build or extend a wired network.  Then a peer to peer workgroup can be established for transfer or access of data.  A member of the workgroup may be established as the server or the network can act in a peer to peer mode as Shown in Figure. brbraitt/dcsonkhla

Access Point

Wireless LAN workgroup brbraitt/dcsonkhla

Access Point Wi-Fi adapters  End users access the Wi-Fi network through Wi-Fi adapters, which are implemented as cards in desktop computers, or integrated within hand-held computers.  Wi-Fi wireless LAN adapters provide an interface between the client Network Operating System (NOS) and the airwaves via an antenna. brbraitt/dcsonkhla

Access Point Wi-Fi adapters 



The nature of the wireless connection is transparent to the NOS. Wi-Fi deals with fixed, portable and mobile stations and of course, the physical layers used here are fundamentally different from wired media

brbraitt/dcsonkhla

Access Point 



A WAP can typically communicate with 30 clients systems located within radius of 100 m. Range of communication can vary a lot depending on:    

   

Indoor or outdoor placement Height above ground Nearby obstruction Oher electronics devices that might actively interfere with the signal by broadcasting on the same frequency. Type of antenna Current weather Operating radio frequency Power output of devices. brbraitt/dcsonkhla

Access Point 







Network designers of WAP use repeaters & reflectors to amplify or bounce the radio signals that ordinarily would go un-received. A typical corporate use involves attaching several WAPs to a wired network. In this case the WAP functions as a gateway for client to access the wired network. Another use involves bridging two wired networks (within line of site) in conditions inappropriate for cable. brbraitt/dcsonkhla

Access Point Lily-pad network  Another wireless topology a Lily-pad network consists of a series of access points spread over a large area, each connected to a different network.  This provides Hot Spots where wireless clients can connect to Internet without regard of particular network to which they have attached to for the moment (coffee house, libraries, public spaces, privately owned open access points etc.).  This allows clients to roam over large area & staying more or less connected. brbraitt/dcsonkhla

Access Point Wireless Community Network  In a society where everyone has his own WAP within range of the neighbor’s WAP it is possible to setup a Wireless Community Network creating intra-city communication network without wires. brbraitt/dcsonkhla

Hotspots  



Hotspots are venues that offer Wi-Fi access. It is a geographic area that has a readily accessible wireless network First proposed by Brett Steward in Aug1993 as “Public Accessible Wireless LANs” and first advanced by NOKIA

brbraitt/dcsonkhla

Hotspots 



HotSpots are equipped with a Broadband Internet connection, and one or more Access Points that allow users to access the Internet wirelessly. Some companies established 300,000 hotspots for free service to entice customers to their venue.

brbraitt/dcsonkhla

Hotspots 





For venues having broadband services offering wireless access is as simple as purchasing one AP and connecting that AP to gateway box. Hotspots are often found at Restaurants, Railway stations, Airports, Library, Coffee shops, Bookstores & public places. Universities & Schools can have wireless network in their campus.

brbraitt/dcsonkhla

Hotspots Free Hotspots services / sites: WiFi FREESPOTS Anchorfree FREESPO Panera Bread Freehotspot.com Google WiFI MetroFi

brbraitt/dcsonkhla

Hotspot Security    



Most hotspots are unsecured. User data is shared by all users. Some hotspots authenticate users. This does not secure data transmission or prevent packet sniffers from allowing people to see the traffic on the network. Some venues offer VPN such as GoogleWiFi, which is expensive option. brbraitt/dcsonkhla

Hotspot Security 

A “Poisoned Hotspot” refers to a free public hotspot hosted up by malicious individuals for the purpose of sniffing the data send by the user.

brbraitt/dcsonkhla

Typical Wi-Fi Users

    



Frequent Travelers Businessmen and Corporate Managers Scientists & Doctors Students and Academicians Administrators & Technocrats who participate in Seminars & Conferences Just about anybody with a laptop

brbraitt/dcsonkhla

Components required for WiFi 

 

A PC, laptop or PDA, running Windows 98 or above. A wireless PCMCIA card, or a wireless adapter. Now a days all the latest LAPTOPS are coming with in built CENTRINO

brbraitt/dcsonkhla

Advantages of Wi Fi 



In a Wi-Fi users can access shared information without looking for a place to plug in, and network managers can set up or augment networks without installing or moving wires. Wi-Fi offers many productivity, conveniences, and cost advantages over traditional wired networks. brbraitt/dcsonkhla

Advantages of Wi Fi





· Mobility: Wi-Fi systems can provide LAN users with access to real-time information anywhere in their organization. This mobility supports productivity and service opportunities not possible with wired networks.

brbraitt/dcsonkhla

Advantages of Wi Fi  

 

Installation Speed and Simplicity Installing a Wi-Fi system can be fast and easy and can eliminate the need to pull cable through walls and ceilings. Installation Flexibility Wireless technology allows the network to go where wire cannot go.

brbraitt/dcsonkhla

Advantages of Wi Fi 



Reduced Cost-of-Ownership The initial investment of Wi-Fi hardware can be higher (gradually coming down), overall installation expenses and life-cycle costs can be significantly lower. Long-term cost benefits are greatest in dynamic environments requiring frequent moves, adds, and changes. brbraitt/dcsonkhla

Advantages of Wi Fi Scalability  Wi-Fi systems can be configured in a variety of topologies to meet the needs of specific applications and installations.  Configurations are easily changed and range from peer-to-peer networks suitable for a small number of users to full infrastructure networks of thousands of users that allow roaming over a broad area. brbraitt/dcsonkhla

Advantages of Wi Fi 

It offers much high speed upto 54 Mbps which is very much greater than other wireless access technologies like CORDECT, GSM and CDMA

brbraitt/dcsonkhla

Limitation of Wi-Fi networks Coverage: 





A single Access Point can cover, at best, a radius of only about 60 metres. Hundreds of Access Points are necessary to provide seamless coverage in small area. For 10 square kms area roughly 650 Access Points are required, where as CDMA 2000 1xEV-DO requires just 09 sites. brbraitt/dcsonkhla

Limitation of Wi-Fi networks Roaming: 

It lacks roaming between different networks hence wide spread coverage by one service provider is not possible, which is the key to success of wireless technology.

Backhaul:   



Backhaul directly affects data rate. Service provider used Cable or DSL for backhaul. Wi-Fi real world data rates are at least half of the their theoretical peak rates due to factors such as signal strength, interference and radio overhead Backhaul reduces the remaining throughput further. brbraitt/dcsonkhla

Limitation of Wi-Fi networks Interference:  Wi-Fi uses unlicensed spectrum, which mean no regulator recourse against interference.  The most popular type of Wi-Fi, ‘802.11’b uses the crowded 2.4 GHz band which is already used in Bluetooth, cordless phones and microwave ovens. brbraitt/dcsonkhla

Limitation of Wi-Fi networks Security:  Wi-Fi Access Points and modems use the Wired Equivalent Privacy (WEP) Standards, which is very susceptible to hacking and eavesdropping. Security:  WEP( Wired Equivalent Privacy) is not very secure.  WPA (WIFI Protected Access) offers much better security with the help of dynamic key encryption and mutual authentication.

brbraitt/dcsonkhla

Limitation of Wi-Fi networks Authentication, Authorization and Accounting: 

 

 

In a server based configuration whenever a laptop enters into a wifi zone, a welcome page is sent to it. User enters username and password. It is connected through the wireless gateway(router) to AAA servers. Once authenticated ,user can access sites of his choice. Prepaid and postpaid customers can be billed.

brbraitt/dcsonkhla

Thank You

brbraitt/dcsonkhla