wireless LAN IEEE 802.11

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