Changeset 2793

Timestamp:

10/30/09 17:15:59 (4 weeks ago)

Author:

wark

Message:

changed dummy

Files:

• HydroWatch/Tim/doc/ipsn10/sec_intro.tex (modified) (1 diff)

HydroWatch/Tim/doc/ipsn10/sec_intro.tex

@@ -11 +11 @@
 in general, breaking through the 1\% duty-cycle barrier for practical deployment scenarios is not possible with current radio technology.
 
-\begin{figure*}[ht]
+Even after radio duty-cycling, idle listening is still one of the major energy consumers of sensor nodes. As shown in as shown in Figure~\ref{fig:energy}(a),  idle listening consumes XX\% over the overall energy budget, compared to just XX\% for sampling and transmitting of data. In other words, a significant energy cost is paid to allow the node to be in a state of ``always on'', and only a small part of the energy is used in the actual sampling and transmission of information\cite{prabal07batch}.
+
+\begin{figure}[ht]
     \centering
-  \begin{tabular}{ccc}
+  \begin{tabular}{cc}
         \includegraphics[width=0.5\columnwidth]{fig/dummy_piechart} &
-        \includegraphics[width=0.5\columnwidth]{fig/dummy_piechart} &
-         \includegraphics[width=0.6\columnwidth]{fig/dummy_graph}\\ 
-        (a) & (b) & (c) \\ 
+        \includegraphics[width=0.5\columnwidth]{fig/dummy_piechart}\\
+         %\includegraphics[width=0.6\columnwidth]{fig/dummy_graph}\\ 
+        (a) & (b) \\ 
     \end{tabular}
-    \caption{(**JAY TO INSERT FIGURES HERE **) Dummy figures showing (a)  A typical energy breakdown for a node running LPL, (b) A typical energy breakdown for a node scheduling the radio (c) A graph of the tradeoff between time-off and energy consumed per bit, relative to LPL always-on.}
+    \caption{(**JAY TO INSERT FIGURES HERE **) Dummy figures showing (a)  A typical energy breakdown for a node running LPL, (b) A typical energy breakdown for a node scheduling the radio}
     \label{fig:energy}
-\end{figure*}
+\end{figure}
 
-Even after radio duty-cycling, idle listening is still one of the major energy consumers of sensor nodes. As shown in as shown in Figure~\ref{fig:energy}(a),  idle listening consumes XX\% over the overall energy budget, compared to just XX\% for sampling and transmitting of data. In other words, a significant energy cost is paid to allow the node to be in a state of ``always on'', and only a small part of the energy is used in the actual sampling and transmission of information\cite{prabal07batch}.
 
 An obvious way to reduce the amount of energy consumed by idle listening is to turn the radio off. Whilst the allows a large amount of energy to be redistributed to tasks such as sampling and sending (when the radio is switched on again), this approach allows incurs an additional network overhead each time the radios are turned back on in where network routing tables must be reformed and [other things?]. Figure~\ref{fig:energy}(c) illustrates the nature of this additional cost, showing the relationship between time the radios are off and the effective energy consumed per bit of data transmitted. Once radios are off long enough, the effect of amortizing the cost of updating the network state over long periods becomes clear where in these cases the net energy cost is less than a typical low-power listening (LPL) MAC \cite{lpl04sensys}.