The document discusses wireless LAN (IEEE 802.11) standards. It describes how wireless LANs provide flexibility, portability and mobility by connecting devices using wireless transmission instead of physical wires. The key wireless LAN standard is IEEE 802.11, which was first published in 1997 and defines the physical and data link layer specifications. The standard provides benefits like interoperability, fast product development and support for future technologies. Common wireless LAN applications include use in medical facilities, schools, temporary situations and emergency response centers.

1. Wireless LAN (IEEE 802.11)Wireless LAN (IEEE 802.11)
V.Parthipan
Assistant Professor
CSE
• Links two or more devices using
a wireless distribution method.

2. LAN/WLAN
• LANs provide connectivity for
interconnecting computing resources
at the local levels of an organization
• Wired LANs
• Limitations because of physical,
hard-wired infrastructure
• Wireless LANs provide
• Flexibility
• Portability
• Mobility
• Ease of Installation

3. IEEE 802.11 Wireless LAN Standard
 Wireless LAN standard – IEEE 802.11
 IEEE published 802.11 in 1997, after seven
years of work
 Most prominent specification for WLANs
 Scope of IEEE 802.11 is limited to Physical and
Data Link Layers.

4. Benefits of 802.11 Standard
o Appliance Interoperability
o Fast Product Development
o Stable Future Migration
o Price Reductions
o Significant differences between wireless and
wired LANs:
oPower Management
oSecurity
oBandwidth

5. Wireless LAN ApplicationsWireless LAN Applications
 Medical Professionals
 Education
 Temporary Situations
 Airlines
 Security Staff
 Emergency Centers

6. Wireless LAN configuration
CM
10 Mbps
Ethernet
switch
UM
Bridge
Or
Router
Server
100 Mbps Ethernet switch
Server

7. • Wireless LAN requirement:-
o throughput – should provide high capacity.
o Number of nodes –should support many data.
o Connectivity of backbone LAN.
o Battery power consumption
o Transmission robustness and security:
o Highly interference prone should provide reliable transfer.
o coallocated network operation –Wireless LAN operating
in same area may face interference.
o License free operation
o
o Hand off (or) Roaming – mobile station can move from
cell to another.
o Dynamic configuration: automated addition or
relocation of end systems without disruption to others.

8. WLAN TopologyWLAN Topology
Ad-Hoc NetworkAd-Hoc Network

9. WLAN TopologyWLAN Topology
InfrastructureInfrastructure

10. Association Related ServicesAssociation Related Services
 Association
Re-association
Disassociation

11. Re-AssociationRe-Association

12. Access and Privacy ServicesAccess and Privacy Services
Authentication
Privacy

13. IEEE 802.11 Medium Access ControlIEEE 802.11 Medium Access Control
• MAC layer covers three functional areas:
• Reliable data delivery
• Access control
• Security

14. Physical Media Defined by OriginalPhysical Media Defined by Original
802.11 Standard802.11 Standard
Frequency-hopping spread spectrum
Operating in 2.4 GHz ISM band
Lower cost, power consumption
Most tolerant to signal interference
Direct-sequence spread spectrum
Operating in 2.4 GHz ISM band
Supports higher data rates
More range than FH or IR physical layers
Infrared
Lowest cost
Lowest range compared to spread spectrum
Doesn’t penetrate walls, so no eavesdropping

15. Future of WLANFuture of WLAN
WLANs move to maturity
• Higher Speeds
• Improved Security
• Seamless end-to-end protocols
• Better Error control
• Long distances
• New vendors
• Better interoperability
• Global networking