The Performance of a Wireless Sensor Network for Structural
Health Monitoring
Jeongyeup Paek, Nupur Kothari, Krishna Chintalapudi, Sumit Rangwala, Ramesh
Govindan
Embedded Networks Laboratory, USCSep. 24. 2004
Wisden
A wireless multi-hop sensor network based data acquisition system for structural health monitoring
Features Time-synchronized data delivery from
multiple sensor nodes Reliable data delivery over multiple
hops with tolerable latencies Ease and flexibility of deployment
Wisden (cont’)
Hardware Mica-2 mote Vibration card : 4-channel, 16-bit ADCs Accelerometer : tri-axis (-2.5g ~ 2.5g)
Reliability Application layer NACK mechanism Hop-by-hop and end-to-end loss
recovery over self-configured tree topology
Wisden (cont’)
Data Compression Lossy run-length encoding for silence
suppression Required to handle the large data volume
Data Synchronization Calculate residence time of a packet
within each node Time-stamp data at the base station
(possibly with GPS)
Wisden deployment
Setup 10 motes in 90’ X
180’ area on the fourth floor of the building
Four nodes co-located with the wired instruments
Tri-axis, with 50Hz sampling rate for each channel
0.5 packets/sec transmission rate
Deployment experiences
High packet loss rate Delivery rate as low as 37.6% for some links
Multi-hop network Maximum of 4-hop paths
Frequent route changes Increased delay for packet loss recovery
Ambient noise Human movements, power generator Interference with other wired/wireless devices
Problems
Lossy Run-length compression Loss of high-frequency components of
data
Time-synchronization Adjusting time takes time
…with GPS at the base station
Software bug Counter wrap-around problem
Seismic Test Structure
Full-scale realistic model of hospital ceilingLocated in the civil engineering building at USC
Conclusion
Our deployments indicate that Wisden can deliver time-synchronized data reliably across multiple hops with tolerable latencies.
However, a number of improvements can be made. Lossless compression Time synchronization
Reference
A Wireless Sensor Network for Structural Monitoring, Ning Xu, Sumit Rangwala, Krishna Chintalapudi,
Deepak Ganesan, Alan Broad, Ramesh Govindan, Deborah Estrin, In Proceedings of the ACM Conference on Embedded Networked Sensor Systems, November 2004
The Performance of a Wireless Sensor Network for Structural Health Monitoring, Jeongyeup Paek, Nupur Kothari, Krishna Chintalapudi,
Sumit Rangwala, Ning Xu, John Caffrey, Ramesh Govindan, Sami Masri, and Daniel Whang, submitted 2nd European Workshop on Wireless Sensor Networks (EWSN 2005)