Changeset 2815

Timestamp:

10/30/09 20:17:01 (4 weeks ago)

Author:

jaein

Message:

 

Location:

HydroWatch/Tim/doc/ipsn10

Files:

• sec_intro.tex (modified) (2 diffs)
• sec_related.tex (modified) (2 diffs)
• sec_sysarch.tex (modified) (1 diff)

HydroWatch/Tim/doc/ipsn10/sec_intro.tex

@@ -11 +11 @@
 A common thread among most of the deployments mentioned is an implicit requirement that the network is 'always available' - the link layer provides the ability to interact with any node in the network at any time. Though this provides a degree of comfort for network operators, it often limits the capacity of the network to make sensor measurements by monopolizing energy resources.  
 
-To get a sense for how much the radio dominates an example environmental sensing application energy budget, we show two pie charts in Figure~\ref{fig:energy}: (a) shows the energy distribution between the hardware components for a node running the Low Power Listening (LPL) radio duty-cycling MAC layer~\cite{lpl04sensys} and (b) shows the same distribution for a node that runs the same LPL layer, but only 10\% of the time; the other 90\% of the time is spent with the radio completely off. Though the radio in each case is the majority consumer, the magnitude of consumption is nearly an order of magnitude less in the latter. This provides an opportunity to reassign the Joules previously reserved for radio idle listening to more useful tasks like increased sensing.
+To get a sense for how much the radio dominates an example environmental sensing application energy budget, we show two pie charts in Figure~\ref{fig:energy}: (a) shows the energy distribution between the hardware components for a node running the Low Power Listening (LPL) radio duty-cycling MAC layer~\cite{polastre04} and (b) shows the same distribution for a node that runs the same LPL layer, but only 10\% of the time; the other 90\% of the time is spent with the radio completely off. Though the radio in each case is the majority consumer, the magnitude of consumption is nearly an order of magnitude less in the latter. This provides an opportunity to reassign the Joules previously reserved for radio idle listening to more useful tasks like increased sensing.
 
 Two challenges arise from this approach - the need to reconstruct routing links and trees after waking up and the increased cost of transmission due to batching. First, examining network reconstruction
@@ -32 +32 @@
 clear reduction in energy that comes about when the radio is off for long-periods (in this case 90\%), where the total consumption is reduced, in this example, to 87$\mu$A.
 
- %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}. 
+ %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{polastre04}. 
 
 The key trade-off in turning off radios is that of network responsiveness. Once nodes only become active in scheduled intervals then the times a user can communicate with nodes, or the times which nodes can report to a base are now constrained. This has clear implications for event-driven applications or query-based systems, where a user may want an immediate responsive from the network.

HydroWatch/Tim/doc/ipsn10/sec_related.tex

@@ -11 +11 @@
 \begin{tabular}{|p{0.09\textwidth}|p{0.1\textwidth}|p{0.1\textwidth}|p{0.11\textwidth}|}
 \hline
-Energy Manage- & \multicolumn{2}{p{0.2\textwidth}|}{Low-power duty-cycling network protocol} & \cite{ye02infocom,tmac03sensys,lpl04sensys,dozer07ipsn,koala08ipsn} \\
+Energy Manage- & \multicolumn{2}{p{0.2\textwidth}|}{Low-power duty-cycling network protocol} & \cite{ye02infocom,tmac03sensys,polastre04,dozer07ipsn,koala08ipsn} \\
 \cline{2-4} 
 ment           & \multicolumn{2}{p{0.2\textwidth}|}{Adaptive duty-cycling with solar energy harvesting} & \cite{jiang05,hsu06,kansal07,vigorito07}, ours \\ 
@@ -48 +48 @@
 Koala \cite{koala08ipsn} provides a lower-duty cycling link-level
 protocol, LPP (Low Power Probing). Similarly to LPL
-(Low Power Listening) \cite{lpl04sensys}, LPP maintains
+(Low Power Listening) \cite{polastre04}, LPP maintains
 inter-node connectivity asynchronously, but it is receiver-oriented
 rather than sender-oriented. With LPP a sender keeps listening until 

HydroWatch/Tim/doc/ipsn10/sec_sysarch.tex

@@ -8 +8 @@
 \begin{figure*}[ht]
 \centering
-  \includegraphics[width=0.9\textwidth]{fig/sysarch2}
+  \includegraphics[width=0.85\textwidth]{fig/sysarch2}
 \caption{Overview of system architecture.}
 \label{fig:sysarch2}