Transcript vega.cs.kent.edu

A System for Simulation, Emulation, and
Deployment of Heterogeneous Wireless
Sensor Networks
Lewis Girod, Thanos Stathopoulos, Nithya
Ramanathan, Jeremy Elson, Eric Osterweil, Tom
Schoellhammer, Deborah Estrin
CENS, UCLA
Presented by David G. Watson
Friday, July 16, 2004
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Heterogeneous Systems
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What hardware platform to use for sensor
networks?
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Authors contend that both are necessary:
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Motes – most scalable platform to support long
battery lifetimes
Microservers – most capable platforms that can
be readily deployed
Many cheap mote-like devices
A few powerful microserver devices
They have developed a software platform to
support both types of device
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Current Simulation Platforms
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TOSSIM
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EmSim
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Simulates motes running TinyOS code
Simulates microservers
Neither one is sufficient to simulate a
heterogeneous system
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Simulating Heterogeneous Systems
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EmTOS: an
extension to EmStar
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Enables a complete
NesC/TOS app to
run unmodified
under EmStar
Can be used either
for deployment or
simulation
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HostMote Protocol
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To communicate with real motes, EmStar
uses the HostMote protocol
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Works over a serial connection
Failure-tolerant – supports hot-swap of motes
HostMote can be used for other things as
well:
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Debugging – motes can transport messages to
microserver
Configuration – reports status of connected mote
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Microserver Participation in
Mote Networks
Microservers can take part in MoteNets in
several ways:
● As a serial gateway: attached mote relays
data to microserver over serial connection
● Re-implement or port NesC application on
microserver platform
● Use EmTOS and extend NesC code under
EmStar
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Modes of Heterogeneous
Simulation
Four modes in which the ESS application may be run under EmTOS
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EmTOS Emulation Modes
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Emulation Mode
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Real Mode
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all physical motes run Transceiver app
programs are run on simulation host
all motes run natively
concentrator is run on the simulation machine
Hybrid Mode
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some motes run Transceiver, some run real code
concentrator runs on sim machine, as do some
motes
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Performance Analysis
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Comparing Timer Jitter between EmTOS and Mica2
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Timer Jitter Scaling in EmSim
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Case 1: One timer, 200ms
Case 2: 3 timers: 100ms, 200ms, 500ms
Case 3: 200ms timer, 120ms timer with 20s task
Ran 3 previous experiments at different scales
Comparative Packet Latency in EmTOS
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Ran tests comparing Ping times between EmTOS
and real motes
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Comparative Timer Jitter
Top row is Mica2, Bottom row is EmTOS
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Timer Jitter Scaling
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Round Trip Time
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Future Work
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Determine how TimeWarp affects fidelity at
scale
See if Kernel 2.6 can improve scalability
Fix the ESS application using the EmTOS
tools
Use an EmView Gateway to funnel real data
into analysis and visualization tools
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