WIRELESS INTERNET

Guide:XXXXXX,XXXXXX

Asst. Professor

XXXX(12XXXXXX)

ECE

ABSTRACT

Wireless LAN, the data transfer while using applications such as

web browser, e-mail client, etc. As the technology is advancing, Wireless

LANs are now also capable of supporting time-sensitive services such as

voice and video.

These services have stringent service requirements from the

network infrastructure. The protocols used for such services are Enhanced

Distributed Coordination Function (EDCF) and Hybrid Coordination

Function (HCF).

 

INTRODUCTION

Wireless?

• A wireless LAN or WLAN is a wireless local area network that uses radio

waves as its carrier.

• The last link with the users is wireless, to give a network connection to all

users in a building or campus.

• The backbone network usually uses cables

Wireless Networking

• Wireless networking is the basic obstacle to be solved for the mobile computing

• Wireless media has different characteristics than the current wired networks

• Data networking protocols are optimized for the current wired networks– The protocols are not efficient in the wireless environments

• Wireless network can be categorized to:– Wireless LAN’s

• IEEE 802.11• Bluetooth

– Wireless WAN’s• GSM, GPRS, CDPD, CDMA, etc…

Internet Protocol• Internet protocols are optimized for megabit per second wire line

connections• Wireless networking solutions

– unrelated to IP• WAP

– solutions on the top of the IP• Mobile IP, optimized IP and TCP, modified TCP

– researched:• LEO and GEO satellite links

• IP packets checksum might not be strong enough– PPP has 16-bit CRC

• IP is end-to-end protocol– designed to operate in a rather homogenous network

TCP/IP TCP optimization

slow start termination/modification• how will the networks congestion propagate, if slow start is

abandoned?• Increased initial sending window

TCP header compression IP payload compression

• some or most of the data is already compressed• files transferred over ftp, published pictures in web

fast retransmit and fast recovery• multiple ACKs notify the sender to adjust the send window and

initiate fast retransmissions of the lost packet

Wireless LAN• Wireless LAN specified in IEEE 802.11 spec• Guarantees multi hardware vendor interoperability • Main features:

– Robust• Data acknowledgement, RTS/CTS, data fragmentation

– Multi channel roaming. Allows multiple cells resulting in higher capacity

– Power management– Automatic rate selection from 1Mbps to 2Mbps– Security WEP (wired equivalent privacy)

Wireless LAN architecture

Wireless LAN architecture

• Cell consists of work stations and an access point

• Access points are interconnected via distribution system (Ethernet)

• The interconnected network forms an extended service set

– Portal connects different 802 based LAN’s

• MAC similar to IEEE 802.3 (Ethernet)

• Offers common access to three physical layer interfaces

– Direct Sequence Spread Spectrum

– Frequency Hopping Spread Spectrum

– Infrared

What is 802.11?

• A family of wireless LAN (WLAN) specifications developed by a working

group at the Institute of Electrical and Electronic Engineers (IEEE)

• Defines standard for WLANs using the following four technologies

– Frequency Hopping Spread Spectrum (FHSS)

– Direct Sequence Spread Spectrum (DSSS)

– Infrared (IR)

– Orthogonal Frequency Division Multiplexing (OFDM)

• Versions: 802.11a, 802.11b, 802.11g.

HOTSPOT

What is a Hotspot? A Hotspot is any location where Wi-Fi network access is made publicly

available.

Hotspot are equipped with a Broadband internet connection, and one or

more Access Points that allow users to access the Internet Wirelessly.

Hotspot can be setup in any public location that can support an Internet

connection.

Advantages

• Mobility• Ease of Installation• Flexibility• Cost• Reliability• Security• Roaming

Disadvantages

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

References

• National Institute of Standards and Technology Wireless

Network Security

http://csrc.nist.gov/publications/drafts/draft-sp800-48.pdf

Conclusion

• Wireless is one of the fastest growing technologies.The Demand for

connecting devices without the use of cables is increasing everywhere.Wi-

fi can be found on colleges campus, offices,& in many public areas.

THANK YOU

Queries ..?