FHWS/FtmPrologic
Archived
4
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

kein plan ey.. intro ist schwer

Browse Source
This commit is contained in:
toni
2019-11-30 18:58:14 +01:00
parent 410d7dc711
commit d674842012
3 changed files with 42 additions and 12 deletions
Download Patch File Download Diff File Expand all files Collapse all files

11
tex/chapters/3_ftm.tex
View File

@@ -103,12 +103,13 @@ Additionally, the computation of the wall-attenuation factor model requires cost
\subsection{Fine Timing Measurement}
Time-based distance measurements are intuitively based on the delay the signal took to travel from the sender to the receiver.
Multiplied by the propagation speed of light results in the distance between the two nodes.
The propagation speed of the signal depends on the propagation medium and is slower in media with higher relative permittivity compared to air, like concrete walls.
However, for most indoor environments the signal propagation speed can be assumed to be constant, as the total travel distance in non-air media is usually negligible short compared to the travel distance in air \cite{marcaletti2014filtering}.
For that reason, time-based distance measurements are assumed to be more robust compared to received power measurements, because the propagation path and interaction with the environment is inherent in the measurement.
%Time-based distance measurements are intuitively based on the delay the signal took to travel from the sender to the receiver.
%Multiplied by the propagation speed of light results in the distance between the two nodes.
%The propagation speed of the signal depends on the propagation medium and is slower in media with higher relative permittivity compared to air, like concrete walls.
%However, for most indoor environments the signal propagation speed can be assumed to be constant, as the total travel distance in non-air media is usually negligible short compared to the travel distance in air \cite{marcaletti2014filtering}.
%For that reason, time-based distance measurements are assumed to be more robust compared to received power measurements, because the propagation path and interaction with the environment is inherent in the measurement.
As mentioned above, time-based distance measurements are intuitively based on the delay the signal took to travel from the sender to the receiver.
A straightforward method to measure the propagation delay of a signal is time of arrival (ToA), where the propagation time of the signal is computed from absolute time values measured at the transmitter and receiver.
This method is used famously in satellite navigation, \eg GPS.
While being precise, ToA requires costly high precision synchronized clocks, which are not suitable for indoor localization.