Commit 66af7916 authored by Archan MISRA's avatar Archan MISRA

removed some gobbledygook material that seemed to crop up mysteriously....

removed some gobbledygook material that seemed to crop up mysteriously. removed spurious comment for Figure 5
parent c7ea6805
......@@ -49,7 +49,7 @@ To minimize the unnecessary energy drain of the wearable device, we adopt a trig
\begin{figure}[!htb]
\centering
\includegraphics[scale=0.5]{triggerwave.png}
\caption{Voltage generate by motion trigger when the magnet moves. \textcolor{blue}{Update tomorrow}}
\caption{Voltage generate by motion trigger when the magnet moves.}
\label{fig:triggervoltage}
\end{figure}
......@@ -58,12 +58,12 @@ We tackle this by including a very simple motion trigger that consumes zero ener
% %%all of this was leftover stuff--doesn't need to be in the paper.
% % Though RF-based energy harvesting is known to be a practical solution for IoT such as RFID tags. WiFi-based energy harvesting has been under utilized because of the low, law-regulated energy of WiFi APs. However, we prove that by carefully designing the whole close-loop system, we can increase the efficiency of WiFi power transfer so that it is practical to use WiFi to power more power hungry device than RFID tags. And we show that a full wearable device with inertial sensor and RF communication interface can survive on power only harvested from WiFi transmissions. We based our study on previous studies of RF-based energy harvesting, beamforming and Direction of Arrival.
Though RF-based energy harvesting is known to be a practical solution for IoT such as RFID tags. WiFi-based energy harvesting has been under utilized because of the low, law-regulated energy of WiFi APs. However, we prove that by carefully designing the whole close-loop system, we can increase the efficiency of WiFi power transfer so that it is practical to use WiFi to power more power hungry device than RFID tags. And we show that a full wearable device with inertial sensor and RF communication interface can survive on power only harvested from WiFi transmissions. We based our study on previous studies of RF-based energy harvesting, beamforming and Direction of Arrival.
% % Our intuition is that WiFi power transfer is inefficient because the antenna emits signal omnidirectionally. This is because it does not know the direction of the device, so it has to transfer the energy into all directions, though the device is located at one direction.
Our intuition is that WiFi power transfer is inefficient because the antenna emits signal omnidirectionally. This is because it does not know the direction of the device, so it has to transfer the energy into all directions, though the device is located at one direction.
Our system is much more efficient because it can detect the direction of the device and form a narrow beam of WiFi signal toward that direction to charge the device. With beamforming, the energy is concentrated within a smaller area so the available energy in those areas is much higher. To achieve this, the system needs the cooperation of the 2 main components: the WiFi AP and the device. We also explore the use of motion trigger mechanism to further reduce the power consumption.
% % Our system is much more efficient because it can detect the direction of the device and form a narrow beam of WiFi signal toward that direction to charge the device. With beamforming, the energy is concentrated within a smaller area so the available energy in those areas is much higher. To achieve this, the system needs the cooperation of the 2 main components: the WiFi AP and the device. We also explore the use of motion trigger mechanism to further reduce the power consumption.
\section{Testbed Implementation}
\label{sec:testbed}
......
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