Project description

SenSearch stands for GPS and Witness Assisted Tracking for Delay Tolerant Sensor Networks, in this project, we use Micaz together with sensorboard MTS420ca/420cc which includes a GPS module. We deployed a real world system and experimented in both uncontrolled and uncontrolled way to prove the robustness of the system and refine the system parameters. The work is a coordinated effort between UC Merced and Uiversity of Colorado, Boulder.

Motivation and challenges

Every year people become lost in places without any tracking system support, e.g. national park. The huge area of this kind of places makes it hard to deploy a system which requires fixed infrastructure such as cell phone networks. We propose using a device with is small, energy efficient and cheap to serve as a automatic recorder of specific objects such as a person. Such a device has to take advantage of the encounter of objects to relay information because we cannot deploy too many stations to keep on downloading information from them. It has to be easy to carry and makes no burden to travelers. It has to balance between the dominating energy consumption of GPS module and localization preciseness. It should take advantage and adapt to the changing circumstance,e.g. grouped traveling and encounter frequency.

System design and implementation

The primary relaying method is transmitting the GPS records between nodes when they encounter. We make the nodes send periodic beacons to probe for any one passing by. We keep the content sent concise and short, using only 9 bytes for time and GPS positions, so it can be finished in the short encounter. Group layer is implemented to take advantage of people who are traveling together, we designate the leader of the group as the one with most power reserve. Group leader has the responsibility to discover any other group leader or nodes passing by and forward the information to the group member so that their GPS module can be turned off and still get all the GPS records.


Lun Jiang, Ankur U. Kamthe, Alberto E. Cerpa, "Wireless Pedestrian Tracking Network," Proceedings of the Seventh ACM Conference on Embedded Network Sensor Systems (SenSys 2009), pp. 393--394, ACM, Berkeley, CA, USA, November, 2009.
Lun Jiang, Jyh-How Huang, Ankur Kamthe, Tao Liu, Ian Freeman, John Ledbetter, Shivakant Mishra, Richard Han, Alberto Cerpa, "SenSearch: GPS and Witness Assisted Tracking for Delay Tolerant Sensor Networks," Proceedings of the Eighth International Conference on Ad-hoc and Wireless Networks (ADHOC-NOW 2009), pp. 255--269, Springer-Verlag, Murcia, Region of Murcia, Spain, September, 2009.
Jyh-How Huang, Lun Jiang, Ankur Kamthe, Richard Han, John Ledbetter, Shivakant Mishra, Alberto Cerpa, "SenSearch: GPS and Witness Assisted Tracking for Delay Tolerant Sensor Networks," UCM Technical Report TR-2006-001, pp. 1--13, University of California, Merced, December, 2006.
Andrew Parker, Athanasios Stathopoulos, Jeremy Elson, Lewis Girod, Ning Xu, Alberto Cerpa, Ramesh Govindan, Deborah Estrin, "Delay Tolerant Networking for Sensor Networks," Second Annual Research Review of the Center of Embedded Networked Sensing (CENS), Los Angeles, CA, USA, March, 2004.


Thanks to

Our thanks go to all the people who volunteered to help us do the experiments.

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