Abstract
The aim of this work is to combine measured and predicted
signal levels in order to improve the accuracy of a
propagation model. In addition to inserting measured
signal levels in the predicted coverage area matrix, new
values og signal level are interpolated around the
measured ones and inserted in the matrix. Three
interpolation techniques have been evaluated: Moving
Least Squares (MLS), Delaunay Triangulation and
Averaging. The first two methods interpolate signal level
values over a wide area with samples from only a few
measurement points, while averaging requires closely
spaced, evenly scattered points.
The purpose of this work has been to build up a database
of signal levels for mobile terminal location. In
addition, the improved coverage area predictions can be
used for network planning purposes.
The standard deviation is of primal interest when the
accuracy of the interpolated signal levels is assessed
because a small standard deviation proves the consensus
between prediction and measurementin signal level
changes. For the propagation model used in this work, the
mean of the standard deviation of the error for seven
test cases is 5.6 dB, compared to 6.1 dB with the MLS
method and 5.1 dB with Triangulation. In cases where
there were no shadowing obstacles present and there were
smooth changes in the signal level, the MLS method gave
better results while Triangulation performed better in
areas with abrupt changes in the signal level. Hence, MLS
should be used for error correction in rural and suburban
areas while Triangulation performs better in urban areas,
metropolises and probably also indoors. The test area is
considered urban. A comparison between all three methods
revealed that in cases of closely spaced uniformly
distributed points Averaging should be used because it
gives the smallest mean value of the standard deviaion
(3.0 dB). Furthermore, with the standard deviation of the
error ranging from 2 to 11 dB interpolation techniques
can be used for signal level prediction purposes
themselves.
Original language | English |
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Qualification | Master Degree |
Awarding Institution |
|
Place of Publication | Espoo |
Publisher | |
Publication status | Published - 2003 |
MoE publication type | G2 Master's thesis, polytechnic Master's thesis |
Keywords
- signal level interpolation
- signal level prediction
- propagation model
- coverage area
- mobile communications