EmStar: A Software Environment for Developing and Deploying Wireless Sensor Networks CENS Research Review October 28, 2005 UCLA CENS EmStar Team

2 Outline Why is EmStar useful? Where is EmStar used?

3 Algorithm/Sensing Heterogeneity Communication (ad-hoc/wireless) Time Synch Calibration Task Scheduling Signal Processing Avoid nesC/ C duplication Inter-platform communication Not all nodes Are 1-hop Poor/dynamic Hard to estimate links System Monitoring (development/deployment) Dynamic topology Logging Process control State inspection/ Interactive Debugging Visualization Remote actuation/ monitoring Numerous Software Requirements Bird Detection Field coverage / Bird Localization Routing Algorithm Remote Management

4 Experimental Systems are… Experimental Prototypes –Bugs –Unexpected and transient behavior Things that will cause trouble: –Multiple asynchronous inter-dependent events Trying to optimize application and make it smart –Unexpected data and environmental conditions We need things to be (in lab and for deployments): –Robust so everything keeps running Can not atomically restart the world Partial failure is normal in large distributed systems Softstate is crucial to success of distributed systems –Diagnosable so you can figure out what the problem is

5 How does EmStar help? EmStar is a layer above Linux designed to enable: –Simulation: Rapid iteration via real-code simulation tools –Robustness: Keep running despite unexpected failures and bugs –Visibility: Easily debug/diagnose running systems –Module Reuse: Leverage existing libraries, tools, and services Emulation Array Node 001 … Emulation Mode HostMote Protocol Transceiver Mote Transceiver Mote Transceiver Mote Transceiver Mote MN Node 002 Node 003 Node N Simulation Framework with real RF channels Visualization Tools ClientServer kfusd.o /dev/fusd/dev/servicename Kernel User Robust multi-process, microkernel architecture

6 What is EmStar? Layer 0: FUSD Low Level IPC Layer 1: Glib Handle events on IPC Layer 2: Device Patterns &Libraries IPC mechanism for a variety of interactions Layer 3: Existing Modules and Services Existing useful components for applications Layer 4: Extra Tools Help run, maintain, and debug application

7 Algorithm/Sensing Heterogeneity Communication (ad-hoc/wireless) Time Synch CalibrationTask Scheduling Signal Processing Avoid nesC/ C duplication Inter-platform communication Not all nodes Are 1-hop Poor/dynamic Hard to estimate links System Monitoring (development/deployment) Dynamic topology Logging Process control State inspection/ Interactive Debugging Visualization Remote actuation/ monitoring EmStar Provides … EmTOS In-memory Logrings EmRun Acoustic Ranging syncd Sensor devices, libraries, staged event driven processing ESS / DSE Statesync, flooding, sinktree RNPlite Emview / xoscope Device files Web server clustersync

8 Transparent Trade-off of Scale vs. Reality Deployment –Time consuming –Difficult to monitor and manage –Little/No out-of-band debugging But by now, it’s bug free..? Pure Simulation –Initial development –“Smoke test” –Fix major design flaws “Emulation” –Real radio channels –Real Mote hardware in the loop –Catch bugs, tune algorithms Reality Deployment Simulation Emulation Scale Test Deployment

9 Enables Mote-Microserver Integration NesC-based Multihop tree routing protocol –Runs natively on motes –Runs in EmTOS wrapper on microserver EmTOS run NesC code on the microserver preventing code duplication EmStar helps with remote management of microserver TimerC Multihop AM RadioCRCPacketClockC Dse EssDse motenic link/mote0 DSE dse/streamdse/query ESS ESS network Mote RF Channel Transceiver (Mica2) Example: ESS ADC Multihop link/mh

10 Acoustic Platform Linux-based wireless platform 4-channel microphone array Distributed acoustic sensing –15-20 nodes surround targets Localize motes Localize and count woodpeckers

11 Sounds fun, but first… Support for time-synchronized sampling? Network primitives for coordination among groups of nodes? Automatic calibration of array location and orientation? Development tools: –Simulation tools, testbeds, visualization Debugging and Deployment tools: –Control groups/individual nodes –Health monitoring –Diagnostic data –Error logs Time Synchonization State Dissemination Sink Tree, Flooding Acoustic Ranging Multilateration Emsim/Emview Ceiling Testbed Emproxy/rbsh Emrun process monitor Status devices Per-process Logrings Emstar provides…

12 Current external users of our prototype system –Ohio State Deployed 200 Stargates running EmStar for the DARPA NEST program Implemented routing layer and software update mechanism Tiered testbed in support of the DARPA NEST program –MIT Mote software development using EmTOS on an ePRB testbed Experiences and feedback –Initial experiences have been generally positive Outside CENS Use

13 Conclusion Thanks for listening! More information at: