19 lines
1.2 KiB
TeX
19 lines
1.2 KiB
TeX
\subsection{\docWIFI}
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The smartphone's \docWIFI{} component provides an absolute location estimation $(x,y,z)^T$ by
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measuring the signal-strengths of nearby transmitters (\docAP{}s) and comparing them with the signal-strengths
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that should be measurable. The latter are determined using a signal-strength prediction model.
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Thus, no fingerprinting is required. Solely the positions of the \docAP{}s must be known beforehand.
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%
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Prediction uses the wall-attenuation-factor model \cite{ebner-15}
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which needs just three parameters:
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the senders transmission power, the attenuation based on the distance from the sender, and the attenuation by floors/ceilings.
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To reduce the setup-time, the same values can be used for all transmitters at the expense of a worse location estimation / higher
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uncertainties.
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\subsection{\docIBeacon{}s}
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If the building is equipped with \docIBeacon{}s, those may additionally be used as absolute location source.
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Like \docWIFI{}, measurements are compared with a model prediction based on the known transmitter position.
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The transmission power of the \docIBeacon{} is transmitted by the beacon itself and does not need any estimation beforehand.
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