Wi-Fi Technology
ARTI J JANSARI
M.E.(C.S.E.):-1ST (E.C.)
CONTENTS
• Introduction• Wi-Fi Technologies• Wi-Fi Architecture• Wi-Fi Network Elements• How a Wi-Fi Network Works• Wi-Fi Network Topologies• Applications of Wi-Fi• Wi-Fi Security• Advantages/ Disadvantages of Wi-Fi
INTRODUCTION
• Wireless Technology is an alternative to Wired Technology ,
which is commonly used, for connecting devices in wireless mode.
• Wi-Fi (Wireless Fidelity) is a generic term that refers to the IEEE 802.11 communications standard for Wireless Local Area Networks (WLANs).
• Wi-Fi Network connect computers to each other, to the internet and to the wired network.
The Wi-Fi Technology
Wi-Fi Networks use Radio Technologies to transmit & receive data at high speed
. The name 802.1 comes from the IEEE committee that standardized it.
• IEEE 802.11b• IEEE 802.11a• IEEE 802.11g
IEEE 802.11b
• Appear in late 1999• Operates at 2.4GHz radio spectrum• 11 Mbps (theoretical speed) - within 30 m Range• 4-6 Mbps (actual speed)• 100 -150 feet range• Most popular, Least Expensive• Interference from mobile phones and Bluetooth devices
which can reduce the transmission speed.
IEEE 802.11a
• Introduced in 2001• Operates at 5 GHz (less popular) • 54 Mbps (theoretical speed)• 15-20 Mbps (Actual speed)• 50-75 feet range• More expensive• Not compatible with 802.11b
IEEE 802.11g
• Introduced in 2003• Combine the feature of both standards (a,b)• 100-150 feet range• 54 Mbps Speed• 2.4 GHz radio frequencies• Compatible with ‘b’• Use OFDM Technology
802.11 Physical Layer
There are three sub layers in physical layer:
• Direct Sequence Spread Spectrum (DSSS)• Frequency Hoping Spread Spectrum (FHSS)• Diffused Infrared (DFIR) - Wide angle
DSSS
• Direct sequence signaling technique divides the 2.4 GHz band into 11 22-MHz channels. Adjacent channels overlap one another partially, with three of the 11 being completely non-overlapping. Data is sent across one of these 22 MHz channels without hopping to other channels.
IEEE 802.11 Data Link Layer
The data link layer consists of two sublayers :
• Logical Link Control (LLC) • Media Access Control (MAC).
802.11 uses the same 802.2 LLC and 48-bit addressing as other 802 LANs, allowing for very simple bridging from wireless to IEEE wired networks, but the MAC is unique to WLANs.
Elements of a WI-FI Network
• Access Point (AP) - The AP is a wireless LAN transceiver or “base station” that can connect one or many wireless devices simultaneously to the Internet.
• Wi-Fi cards - They accept the wireless signal and relay information. They can be internal and external. (e.g PCMCIA Card for Laptop and PCI Card for Desktop PC)
• Safeguards - Firewalls and anti-virus software protect networks from uninvited users and keep information secure.
How a Wi-Fi Network Works
• Basic concept is same as Walkie talkies.• A Wi-Fi hotspot is created by installing an access point to an
internet connection.• An access point acts as a base station. • When Wi-Fi enabled device encounters a hotspot the device
can then connect to that network wirelessly.• A single access point can support up to 30 users and can
function within a range of 100 – 150 feet indoors and up to 300 feet outdoors.
• Many access points can be connected to each other via Ethernet cables to create a single large network.
Wi-Fi Network Topologies • AP-based topology (Infrastructure Mode)
• Peer-to-peer topology (Ad-hoc Mode)
• Point-to-multipoint bridge topology
AP-based topology
• The client communicate through Access Point. • BSA-RF coverage provided by an AP.• ESA-It consists of 2 or more BSA.• ESA cell includes 10-15% overlap to allow roaming.
Peer-to-peer TOPOLOGY
• AP is not required.• Client devices within a cell can
communicate directly with each other.
• It is useful for setting up of a wireless network quickly and easily.
Point-to-multipoint bridge TOPOLOGY
This is used to connect a LAN in one building to a LANs in other buildings even if the buildings are miles apart.These conditions receive a clear line of sight between buildings. The line-of-sight range varies based on the type of wireless bridge and antenna used as well as the environmental conditions.
Wi-Fi CONFIGURATION
Wi-Fi CONFIGURATION
Wi-Fi CONFIGARATION
Wi-Fi APPLICATION
• Home• Small Businesses or SOHO• Large Corporations & Campuses• Health Care• Wireless ISP (WISP)• Travellers
Wi-Fi Security
The requirements for Wi-Fi network security can be broken down into two primary components:
• Authentication User Authentication Server Authentication
• Privacy
Wi-Fi Security Techniques• Service Set Identifier (SSID)
• Wired Equivalent Privacy (WEP)
• 802.1X Access Control
• Wireless Protected Access (WPA)
• IEEE 802.11i
ADVANTAGES
• Mobility• Ease of Installation• Flexibility• Cost• Reliability• Security• Use unlicensed part of the radio spectrum• Roaming• Speed
LIMITATION
• Interference• Degradation in performance• High power consumption• Limited range
CONCLUSION
For now Wi-Fi provides broad band internet access to specially outfitted PCs and Laptops. But in future may be hotspots be wireless.
By Wi-Fi our time and money are saved. The technologies have help Wi-Fi “Hotspots are
becoming more popular throught urban envirnment.”
REFERENCE
www.Wi-Fitechnology.com www.webopedia.com www.wavewireless.com
THANK YOU
