DLink
shows a concentration of power around 50Hz indicated by the strong rising
slope in the NCS. The strong rising slope of the NCS for Lucent indicates a
concentration of power around 10Hz (and 100 Hz).
To numerically compare the spectrum between RIs, we locate the frequency
points that exhibit the greatest amount of power. These key frequency
points estimate the most prevalent sending rates of the RI during rate switching.
For our evaluation, we chose the top 50 frequency points to constitute a
frequency set, F = f1, f2, f50, as the spectral profile of an RI. Table 1 displays
the distribution of the set F for each RI. By examining the range where the
majority (54% or more) of the set F is located, we can distinguish between
RIs. A Lucent RI can be identified by 54% of frequencies concentrated between
0-10Hz. This indicates that a Lucent RI most often sends data frames at a
rate of 100ms during rate switching. The concentration of F for the Linksys RI
is over a broader range: 56% between 80-130Hz. A Linksys RI most often attempts
to send data frames between 7.7ms and 12.5ms during rate switching.
Whereas, DLink most often sends data frames between 17ms and 25ms, indicated
by a concentration of 54% of the set F between 40??“60Hz. The selection
Fig. 8. PSD and cumulative PSD for repeated Lucent experiment.
439
0 50 100 150 200 250
0
20
40
PSD
Lucent2
0 50 100 150 200 250
0
0.2
0.4
0.6
0.8
1
Frequency(Hz)
Cumulative PSD
Cherita Corbett, John Copeland, and Raheem Beyah
Table 1.
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