% $Id: methodology.tex,v 1.2 2005/04/08 13:47:04 gokhale Exp $

\subsection{Evaluation Methodology}
\label{sec:methodology}

This section describes the methodology we used to evaluate EASM. 
We implemented the EASM scheme in the NS-2~\cite{NS-2} discrete
event simulator 
% Amogh, due to double blind reviewing I am commenting this out.
% (the source can be downloaded from
% https://www.dre.vanderbilt.edu/~amoghk/easm). 
We conduct this study to  (1) verify that the scheme works by way of
simulation (2) compare and contrast it against the existing schemes and 3. 
understand the effect of {\em sink movement} on EASM.

The underlying MAC layer was IEEE 802.11, the physical radio 
characteristics of each node's network interface, such as transmit 
power, receiver sensitivity, data load and antenna type were chosen 
so as to approximate the Lucent WaveLan direct sequence spread spectrum
radio. The evaluations were based on the simulation of sensor nodes
which were distributed and moving within a square flat space of 
1000m X 1000m. The mobility model used was the random waypoint 
model~\cite{Johnson_RWP:96,Bettstetter:03}. 

Reports were generated by source nodes every 0.25 seconds. The simulations 
were run with movement patterns generated for pause times including 10, 25, 
40, 50 and 75 seconds. The maximum sink speed values used for simulation 
were 1, 2, 5, 10, 20 and 30 meters/second. The metrics chosen for analyzing
EASM behavior were: (1) Aggregate Energy Depletion - Overall reduction in 
energy level during simulation. (2) Average Delay - Latency seen by the sink 
node in obtaining reports of interest from the source node, averaged for all 
sink-source pairs. (3) Routing Overhead -  Total number of routing packets that 
a node transmits in a network for the duration of simulation. We average 
this value for all the nodes in simulation. (4) Packet Delivery Fraction - 
Fraction of number of packets received at the sink to the number of packets 
being sent from the source nodes. The fraction is averaged for all the 
sink-source pairs for each network density in the simulation.

Simulations were run for 100 seconds and has 4 source and 4 sink nodes.
