1. Mr. Zeeshan Ali, Asst. Professor
Wireless Networking
Mr. Zeeshan Ali, Asst. Professor
Department: B.E. Electronic & Telecommunication
Subject: Wireless Network
Semester: VIII
Teaching Aids Service by KRRC Information Section

2. Introduction What is a wireless network?
A technology that enables two or more entities to communicate without network cabling

3. Different Wireless Networks
IrDA (Infrared Data Association)
Uses beams in the infrared light spectrum
Bluetooth
Uses 2.45 gigahertz radio waves, but emits weak signals
Limits distance to 10 feet, but travels through walls
HomeRF (SWAP) – developed by businesses
6 voice channels and 1 data channel
Slow, and limited range, but cheap

4. Wireless Fidelity (Wi-Fi)
Essentially, this technology is a variation of the IEEE specification known as b
Focuses on Direct-Sequence Spread Spectrum (DSSS)
High data rate (max of 11 Mbps)
In the case of interference, speed drops in halves (11 Mbps to 5.5 Mbps to 2 Mbps to 1 Mbps)

5. Wi-Fi Advantages: Disadvantages: Fast (11 Mbps) Reliable
Long Range (up to 1000 ft outdoors, 400 ft indoors)
Easy integration to wired networks
Compatible with original DSSS standard
Disadvantages:
Speed may fluctuate

6. 802.11a vs. 802.11b Frequency Coverage Distance
802.11b transfers at 2.4 gigahertz
802.11a transfers at 5 gigahertz
Coverage Distance
802.11b goes about 400 feet indoors
802.11a goes about 60 feet indoors
Need more access points to cover a location
Compatible to each other?
Not yet.

7. ITL Wireless Equipment
2 Wireless Access Point Routers (with built in 4 port switch)
Wired Equivalent Privacy (WEP) available
8 Wireless PCMCIA Cards
4 ORiNOCO Gold 11 Mbps PC Cards
4 3Com 11 Mbps PC Cards

8. Wireless Access Point LINKSYS Model No. BEFW11S4 ver. 2 Supports
IEEE (10BaseT)
IEEE 802.3u (100BaseTX)
IEEE b (Wireless)
Built-in router capability
Obtains a Clarkson IP and uses DHCP
Built-in 4 port switch
Fully-configurable through simple web interface

9. Wireless Cards 11Mbs 802.11b compatible 4 3Com Cards
Model No. 3CRWE62092A
4 ORiNOCO (Lucent) Cards
Model No /G

10. Performance Inside Range Outside Range anywhere except in bathrooms
Usually 11 Mbps connection
Outside Range
To the SC lecture wing door (closest to ERC)
Covers faculty lot next to ERC
Half way to Rowley
Connection slows as move away from access point

11. Summer Research Protocol Method of Communication Spoken Language
Networked Programs (AIM)
HTTP, Telnet, FTP

12. Two Main Protocols (Internet)
UDP (User Datagram Protocol)
Fast, bare-bones, not reliable or friendly
Can lose data at any time
TCP (Transmission Control Protocol)
Slower, many features, very reliable
All data will get to the other side

13. PCAttcp Measuring tool for TCP and UDP Speed, Throughput, Time
Amount of Data Sent vs. Amount Received

14. Our PCAttcp Controller
Enhanced UDP transfers
Automated the entire process
Created an easy way to compile results and graphs using a spreadsheet for output
Ran tests on various types of connections

15. The End!
Thoughts or questions?

16. References http://www.howstuffworks.com/wireless-network.htm

17. Different PCATTCP Trials
Same Switch (same lab)
Same LAN (inside Clarkson)
Note: LAN stands for “Local Area Network”
Same Host (same computer)
LAN to LAN (Clarkson to SUNY Potsdam)
LAN to Internet (Clarkson to a Roadrunner service)

18. Bluetooth (cont)
spread-spectrum frequency hopping – a device will use 79 individual, randomly chosen frequencies within a designated range, changing from one to another on a regular basis
When two Bluetooth devices come in contact with each other, they automatically conversate and form a personal-area network (PAN)

19. Spread spectrum
Spread-spectrum – data is sent in small pieces over a number of discrete frequencies available for use at any time in the specified range

20. Frequency-hopping spread spectrum
send a short burst of data, shift frequencies (hop) and then send another short burst
Since the FHSS devices that are communicating agree on which frequencies to hop to, and use each frequency for a brief period of time (less than 400 milliseconds) before moving on, several independent FHSS networks can exist in the same physical area without interfering with each other

21. Direct-sequence spread spectrum
splitting each byte of data into several parts and sending them concurrently on different frequencies
DSSS uses a lot of the available bandwidth, about 22 megahertz (MHz).

22. The Basics 4 different types of wireless networks
IrDA (Infrared Data Association)
Bluetooth
HomeRF (SWAP)
“Shared Wireless Access Protocol”
WECA (Wi-Fi)
“Wireless Ethernet Compatibility Alliance”

23. IrDA (Infrared Data Association)
Uses beams of light in the infrared spectrum
Remote controls
Fairly reliable and low-cost
Drawback: It is a “line-of-sight” technology
less interference
Drawback: “one-to-one” technology
You can send data only between two things at once (but increased security?)

24. Bluetooth The magic number: 2.45 gigahertz
Radio-frequency also used by baby monitors, garage door openers, and cordless phones
How do you avoid interference?
Bluetooth sends weak signals of 1 milliwatt
Powerful cell phones use 3 watts
Bluetooth devices limited to 10 meters
But they can go through walls better than others

25. HomeRF (SWAP) Shared Wireless Access Protocol (SWAP)
Developed by an alliance of businesses
6 voice channels and one data channel
The data channel is the wireless-Ethernet specification by the IEEE
One drawback: SWAP can only be used with computers
Printers and such need to be attached to a computer and used as a resource

26. HomeRF (SWAP) Advantages: Drawbacks: Cheap, easy-to-install
Allows multiple-networks in the same location
Can encrypt data
Drawbacks:
Not very fast (typically limited to 1 Mbps)
Limited Range (75 to 125 ft)
Physical obstructions (walls, large metal objects) cause huge interference issues
Difficult to integrate into existing wired networks