1. Wireless
LAN

2. LAN(local area network)
It is a communication network that interconnects variety of devices and provides means of information exchange among these devices
Its scope may be a small room, a building or a cluster of buildings

3. WLAN(Wireless LAN)
LAN that makes use of wireless transmission media is called as wireless LAN i.e. WLAN
Instead of being an alternate it may be called as extension to LAN
It is used to provide final connectivity of few meters between backbone wired network and end mobile users

4. MCU WAP MCU – Master Control Unit WAP – Wireless Access Point Node-1
Wireless transmission medium

5. Access point : Should have NIC (Network Interface Card)
Hub antenna : located at center or corner
Line of sight : not necessary but desirable
Frequency used may be
Licensed (require high length of paper work from FCC)
Unlicensed (does not require paper work but suffers inference from barcode , scanners etc)
Standards used may be
de-facto ( approved by individuals or organizations that don’t have national international recognition)
De-jure(approved by nationally internationally approved organizations)

6. Advantages Flexibility Planning Installations Robustness Scalability
Cost
Improved productivity and service

7. Disadvantages Quality of service Proprietary solutions Restrictions
Safety and security

8. Applications

9. Design and principle of operation

10. Configurations of
WLAN
Infrastructure
WLAN
Ad hoc
WLAN

11. Infrastructure WLAN

12. communication take place between node(user) and AP
No direct communication between Nodes
AP act as bridge
AP takes care of all network Functionality
so nodes can be Simple
two small networks can form single big logical network
Flexibility is less

13. Ad hoc WLAN Or
Peer to peer WLAN

14. communication take place directly between nodes
Access point is not present
Here the clients need to take care of network functionality, hence nodes are complex
two nodes can communicate with each other only if they are in range
they are quite flexible , for setting up fast network such as for meetings ,Conferences etc

15. comparison Ad hoc WLAN Infrastructure WLAN
Communication take place directly between nodes
AP is not present
Complexity of each node is higher as it need to implement MAC mechanism, mechanism to handle hidden or exposed terminal to provide certain quality of service
Communication take place through AP and no direct communication between nodes
AP act as a bridge between wired and wireless network
All the network functionality lies in the AP point and hence client remain quite simple

16. Ad hoc WLAN Infrastructure WLAN
Nodes that are not in direct range of each other can also communicate through AP
Two small networks can be combined to form a larger logical network
Flexibility is less
Eg: hyperlan
Nodes that are in each others range can only communicate
Such network expansion is not possible in Ad hoc WLAN
More flexible
Eg: Bluetooth

17. Micro cell and roaming

18. Transmission technologies
Wireless LAN
Transmission technologies Or
Types of wireless LAN

19. Wireless LAN transmission technologiesOr
Types of wireless LAN
Infrared WLAN
Radio WLAN
Spread
spectrum
Narrow
band

20. Infrared WLAN Strengths and weakness
constructed using infrared portion of spectrum
Strengths and weakness
strengths:
unregulated spectrum
infrared shares some properties of visible light
-diffusely reflected by light colored objects . Thus ceiling reflection can be used to provide coverage of entire room.
-infrared cant penetrate , hence can be protected against eavesdropping

21. spectrum virtually unlimited hence high rates possible
equipments used are LED and photo diode which are simple and inexpensive
IR data transmission generally use IM so the detector needs to detect only amplitude which quite simple
electrical devices does not cause any interference

22. Weakness:
background radiation, e.g. ssunlight, indoor lighting appear as noise.
Line of sight is compulsory as it cant penetrate
Increase in transmitter power is also limited by concerns of eye safety

23. Transmission techniques of IR:
Directed
Beam IR
Omni-directional
Diffusion

24. 1) Directed Beam IR Point-to-point links
Range depends on power and focusing
-Can be kilometers
-Used for building interconnect within line of sight
Indoor use to set up token ring LAN
IR transceivers positioned so that data circulate in ring

25. 2) Omni directional IR
Single base station within line of sight of all other stations
-Typically, mounted on ceiling
Acts as a multiport repeater
Other transceivers use directional beam aimed at ceiling unit

26. 3) Diffused directional IR
Transmitters are focused and aimed at diffusely reflecting ceiling
IR striking the ceiling are reradiated and picked up by the receiver in the area