Measurements and Models of 802.11B Signal Strength Variation Over Small Distances
Date
2010
Authors
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Publisher
University of Delaware
Abstract
This thesis presents results froma comprehensive channel measurement study.
The 802.11 b/g channel was studied in 25 locations, including 14 indoor channels
and 11 outdoor channels, where each measured used 11 wide bandwidths channels.
For each location, measurements were taken along a 3 meter strip with 1.5 cm between
each measurement, where the location of each measurement was controlled
by a robotic linear actuator. Several hundred measurements were taken at each
location, ensuring precise estimate of the signal strength. In all, 77 million signal
strength measurements were made. However, in order to develop and verify the
quality of the measurement, far more measurements were made. The collected data
was used to estimate the change in signal strength as a function of the displacement.
The observed change in signal strength wasmodeled with a standard channel
model that contains a fast fading component and a lognormal shadowing component.
While this standard model provided a good fit, we found that the lognormal
shadowing component has much less spatially correlated than previous studies had
found. Thus, this thesis developed a new model for the correlation of lognormal
shadowing. Considering that the 802.11 b/g channel is a wide bandwidth channel
(which reduce channel variations caused by fast fading), this study finds more
significant variations in signal strength than has been previously known.