Wi-Fithe

802.11 Standard

VIPUL KUMAR MAURYACSE Department, 3rd Year

IntroductionWi-Fi Stands for Wireless Fidelity

Wireless Fidelity is generic term refers to (The Institute of Electrical and Electronics Engineers ) IEEE 802.11 standards for Wireless Local Area Network.

Wi-Fi is a wireless technology that uses radio frequency to transmit data through the air.

Wi-Fi Network Connects Computer to each other, to the internet and to the wired network.

Wi-Fi Works On IEEE 802.11 Standards 802.11 is primarily concerned with

the lower layers of the OSI model. Data Link Layer

Logical Link Control (LLC). Medium Access Control (MAC).

Physical Layer Physical Layer Convergence Procedure

(PLCP). Physical Medium Dependent (PMD).

802.11 Standards

IEEE 802 .11 bIEEE 802 .11aIEEE 802 .11gIEEE 802 .11nIEEE 802 .11ac

IEEE 802.11 is a set of media access control (MAC) and physical layer (PHY) specifications for implementing wireless local area network (WLAN) computer communication in the 2.4, 3.6, 5, and 60 GHz frequency bands

802.11b Standard Appears in late 1999 Operates at 2.44Ghz radio spectrum 11Mbps (theoretical speed)- within 30 meter Range 4-6 Mbps Actual Speed 100-150 feet range Limits the number of access points in range of each

other to three Most Popular , Least Expensive Interference from Mobile Phones and Bluetooth

device which can reduce transmission speed Uses direct-sequence spread-spectrum technology

802.11a Standard Introduce in 2001 Operates at 5GHz Less popular and Less interfered 54 Mbps (theoretical Speed) 15-20 Mbps (Actual Speed) 50-75 feet range More Expensive Highly Obstructed Not Compatible with 802.11b Uses frequency division multiplexing

802.11g Standard Introduce in 2003 Combine features of both a and b 100-150 feet range 54 Mbps (theoretical speed) 20-25 Mbps (actual Speed) 2.4 GHz radio frequency Compatible with b Uses frequency division multiplexing

802.11n Standard 802.11n also known as Wireless N 802.11n Ratified in 2009 802.11n builds upon previous 802.11 standards by

adding multiple-input multiple-output (MIMO). Operates on Both 2.4Ghz and 5Ghz Provide Bandwidth up to 300Mbps Backward-compatible with 802.11b/g gear Increased Speed and range

802.11ac Standard Builds on 802.11n ,Published in 2013 The addition of Multi-user MIMO (MU-MIMO) Utilizes dual band wireless technology Support Connection both 2.4 GHz and 5GHz Backward compatibility to 802.11b/g/n Bandwidth rated up to 1300 Mbps on the 5 GHz bandwidth rated up to 450 Mbps on the 2.4 GHz

Elements Of Wi-Fi Access Point- The AP is wireless LAN radio transceiver or

“base station” that can connect to one or many wireless devices simultaneously to internet.

Wi –Fi Card- They accept wireless signal and relay information. They can be external or internal.

Safeguards – Firewalls and anti-virus protects from uninvited users and keep information secure.

Wi-Fi Network Topologies

Peer to Peer Topology (Ad-hoc mode) AP – Based Topology (Infrastructure mode)

Peer to Peer Topology AP is not required Client devices can communicate with each other

directly Useful to create wireless network easily and quickly

Infrastructure Network The client communicate through Access point Any Communication has to go through AP If a Mobile station like PDA, Computer has to

communicate with other Mobile station, it need to sends information to AP first , then AP sends Info to destination mobile station

How Wi-Fi Works? A Wi-Fi hotspot is created by installing an access point to an

internet connection. An Access Point acts as base station When a Wi-Fi enabled device encounters a hotspot the

device can then connect to that network wirelessly. A computer’s adapter translate data into radio signals and

transmits it using antenna A Wireless router receives the signals and decode it. Router

sends the information Many access points can connected to each other via

Ethernet cables to create a single large network.

CSMA/CA Carrier Sense Multiple Access with Collision Avoidance CSMA/CA is used by Data Link Layer. MS (mobile station) sends its packets, it checks to see if someone else

is sending information. Only when the medium is free can an MS sends packets.

If some station is sending or receiving signal, the MS that intends to send will generate a random waiting time and wait for its turn. If several MSs are all waiting for their turns, since their waiting times are randomly generated and thus not equal, they will not start sending simultaneously. Thus collision (two or more MSs sending signals simultaneously) is avoided.

Security

Wired Equivalency Protocol (WEP) Wi-Fi Protected Access (WPA) Wi-Fi Protected Access 2 (WPA2) Extensible Authentication Protocol (EAP) Firewall

Advantages

Freedom – You can work from any location that you can get a signal.

Setup Cost – No cabling required. Flexibility – Quick and easy to setup in temp or

permanent space. Scalable – Can be expanded with growth. Mobile Access – Can access the network on the

move.

Disadvantages

Speed – Slower than cable. Range – Affected by various medium.

Travels best through open space. Reduced by walls, glass, water, etc

Security – Greater exposure to risks. Unauthorized access. Compromising data. Denial of service.

Thank You