SCIENCE FAIR:
EXAMPLE TOPICS IN WIRELESS COMMUNICATIONS:
DETERMINING CELLULAR TELEPHONE COVERAGE AREA:
On average, a cellular telephone tower costs $150,000 to construct, a value which does
not include the amount of money required to purchase/lease the land that it is on. For this
reason, cellular carriers do not want to build any more towers than is necessary to provide
“sufficient” coverage to its customers. The sufficiency of a coverage area is usually
measured in available rates (i.e. as a cellular provider, I guarantee that my customers will
be able to communicate at least 1,000 bits per second over 90% of Cambridge). If too few
towers are constructed, then a company cannot provide sufficient service, and if too many
towers are constructed, then money is wasted. Thus, cellular planning is a very important
(and very difficult) aspect of cellular service. The number of “bars” shown on your cell
phone gives a measure of the power that the cell tower is receiving from your cellular
phone. By taking measurements at many spots around Cambridge, the overall coverage of
the Cambridge area can be determined. From this data, and from taking note of cell tower
positions, suggestions can be made about the effectiveness of the coverage area and the
efficiency of current cell site planning.
DETERMINING EFFICIENT PLANNING OF WiFi NETWORKS:
For similar reasons to those outlined above, WiFi networks need to be planned
efficiently. This is especially true for large environments (such as office buildings,
airports, schools, and even on beaches) in which many “hotspots” (or access points) are
required to provide all occupants with a minimum data-rate. A laptop equipped with a
wireless network card can communicate with a data-rate that is specified by how much
power it is receiving from the access point (the computer will let you know what rate it
can currently support). By determining the WiFi coverage of a building, and noting the
positions of access points as well as the geometry of the building, draw conclusions on
how a given building can best be planned to ensure all users will be able to communicate
at a given minimum rate.
HOW WELL CAN WIRELESS SIGNALS PROPAGATE THROUGH
DIFFERENT MATERIALS:
Because signals propagating through the air have extremely complex behavior, engineers
typically rely on measurements of the wireless channel to determine how effectively
signals can propagate. It is clear that radio frequency signals have the ability to penetrate
into solid materials however, as described in the attached material, a loss in power will be
incurred. An interesting project idea would be to determine how much power loss (or a
measure thereof) is incurred by a signal penetrating through certain building materials.
Results from this data can be generalized to give insight into efficient site planning for
WiFi systems as detailed above.
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Check out the website,
http://www.juliantrubin.com/electronicsprojects.html#electronicsfair
for more ideas of science fair projects dealing with communications (both wireless and
wired). Remember that the ideas given above are merely suggestions and can be used as
starting points for developing your own ideas. Please do not hesitate to contact me at the
email address bellorad@fas.harvard.edu for any help developing ideas or test procedures.
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