Motorola MOTOwi4 Canopy 30, User Manual

Page: 83 / 162

Issue 3.1, July 2006 Page 83 of 162
The Spectrum Management algorithm collects measurements equally from all channels. This
process is called the Channel Availability Check (hereafter referred to by the acronym CAC).
The CAC uses a round-robin channel select process to collect an equal amount of
measurements from each channel. It is important to note that the CAC measurement process is
not altered by channel barring process. Measurements are still collected for all channels
irrespective of the number of barred channels.
Measurement Analysis
Spectrum Management uses statistical analysis to process the received peak and mean
measurement. The statistical analysis is based on a fixed, one minute, measurement
quantization period. Spectrum Management collects data for the specified quantization period
and only at the end of the period is the statistical analysis performed. The analysis produces
four key metrics for each channel:
•
Peak of Peaks
•
Peak of Means
•
99.9% Percentile of the Means
•
Mean of Means
Peak of Peaks is the largest peak interference measurement encountered during the
quantization period. This metric is useful for detecting large short duration spikes in the
interference environment.
Peak of Means is the largest mean interference measurement encountered during the
quantization period. The peak of means is similar to the peak of peaks and is useful for
detecting slightly longer duration spikes in the interference environment.
99.9% Percentile of the Means is the value of mean interference measurement for which
99.9% of all mean measurements fall below during the quantization period. The 99.9%
percentile metric is useful for detecting short duration repetitive interference that by its very
nature has a minimal effect of the mean of means.
Mean of Means is the arithmetic mean
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of the measured means during a quantization period.
The mean of means is a coarse measure of signal interference and gives an indication of the
average interference level measured during the quantization period. The metric is not very
good and predicting intermittent interference and is included to show the spread between the
mean of means, the 99.9% percentile and the peak of means.
Note: Spectrum Management uses the 99.9% percentile as the prime interference
measurement. All subsequent references to interference level refer to this percentile
measurement.
The display of statistical measurement on the spectrum management page always shows a
statistical summary of all channel measurement. The statistical summary is controlled by the
Statistics Window attribute. This attribute defaults to a value of twenty minutes, which means
that the mean and percentile values displayed for each channel are calculated over the 20
minute period. All channel decisions are made using the values computed over the statistics
window period.
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The arithmetic mean is the true power mean and not the mean of the values expressed in
dBm.