Figure 1
Revised: September 22, 2005
By Richard G. Baldwin
File: FwlProj130.htm
This laboratory project was prepared specifically for the benefit of my students who are enrolled in ITNW 1351, Fundamentals of Wireless LANs.
The project was designed under the assumption that students enrolled in the course have successfully completed the prerequisite course, ITNW 1325, Fundamentals of Networking Technologies.
The project design also assumes that the students are actively studying the material in the prescribed textbook for this course, which explains such complex topics as the IEEE 802.11g wireless specification.
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You were introduced to the program named NetStumbler in an earlier project.
Although it is not considered to be a site survey tool, NetStumbler can also be used to gather information for a basic site survey. In this project, you use NetStumbler to obtain signal to noise ratio information at various locations within the building.
The following equipment is required to complete this laboratory project:
See Lab Project 7 for background information on the NetStumbler program.
For this project you will start and configure two or more 802.11g wireless routers running within range of your computer.
Then you will start NetStumbler running on a laptop computer.
Then you will roam throughout the building and the grounds outside the building and note the SNR at different locations.
Configure the wireless routers being careful to make certain that they have different SSIDs and are operating on channels that are separated by at least five channels. Also make certain that they are protected by a WEP key.
Place the two routers in different ends of the laboratory.
Start the NetStumbler program running on the laptop computer. You should see an output similar to Figure 1 on the screen.
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Expand the items in the left pane of NetStumbler by clicking the + signs.
The column SNR shown in Figure 2 gives the strength of the signal divided by the noise level and is measured in decibels. Roam with the laptop computer throughout the building and around the grounds outside the building. Observe the fluctuations of the SNR value for the different routers as you roam around.
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Double-click on one of the routers in the right pane to display the graphic SNR as shown in Figure 3. Continue roaming and observe the graphic SNR at different locations in and around the building. Also observe how the graphic SNR varies as you move through the building.
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While you are doing this, pay attention to the possibility that additional wireless networks may be detected at different locations while you are roaming. Pay attention to whether or not those networks are protected.
Copyright 2005, Richard G. Baldwin. Reproduction in whole or in part in any form or medium without express written permission from Richard Baldwin is prohibited.
Richard has participated in numerous consulting projects and he frequently provides onsite training at the high-tech companies located in and around Austin, Texas. He is the author of Baldwin's Programming Tutorials, which have gained a worldwide following among experienced and aspiring programmers. He has also published articles in JavaPro magazine.
In addition to his programming expertise, Richard has many years of practical experience in Digital Signal Processing (DSP). His first job after he earned his Bachelor's degree was doing DSP in the Seismic Research Department of Texas Instruments. (TI is still a world leader in DSP.) In the following years, he applied his programming and DSP expertise to other interesting areas including sonar and underwater acoustics.
Richard holds an MSEE degree from Southern Methodist University and has many years of experience in the application of computer technology to real-world problems.
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Figure 2
Figure 3