utilizing physical layer information to improve rfid tag
utilizing physical layer information to improve rfid tag
utilizing physical layer information to improve rfid tag
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Figure 6.10. Random number distribution for <strong>tag</strong> C.<br />
<strong>to</strong> then estimate the number of remaining <strong>tag</strong>s in the field <strong>to</strong> decide the Q value for<br />
the next round.<br />
A Gaussian PDF is defined by its mean and variance. For our simulation we<br />
keep the variance constant at 2 Q /4. Fig. 6.17 shows the different Gaussian PDFs<br />
that were used in the simulation. Fig. 6.18 shows the results obtained from the<br />
simulation. We observe that there is not a significant difference in the identification<br />
time. However, when the Q value changes from 5 <strong>to</strong> 6(64 <strong>tag</strong>s) and from 6 <strong>to</strong> 7(128<br />
<strong>tag</strong>s) and when the mean is less than 2 Q /2, which is in the case of m=1/3 and m=1/4,<br />
performance decreases. This could be due <strong>to</strong> the fact that having the mean in the<br />
first half causes more collisions during estimation and gives a larger estimate than<br />
the true value of the number of <strong>tag</strong>s remaining.<br />
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