Russell Sears, Murali Rangan
Introduction
Many sensor network deployments are done for scientific exploration studies like [Civi], [Habi]. In such deployments, the primary goals are a) to reliably gather as much sensor data recordings as possible for offline analysis b) to keep the network alive for a very long period of time and c) to be able to collect sensor readings for a long time by reusing storage. We aim to gather data at the base station in a steady stream, but we do not guarantee real time data collection. We assume that the application can tolerate sensor recordings arriving out of order or with unbounded latency, as long as the primary goals stated are met. We intend to design, implement and study a simple routing protocol in a simulation setting that can achieve the stated goals.
Related Work
Various options for reliable data transfer under divergent, convergent and point-to-point routing are evaluated in [Kim], but they focus mainly on point-to-point routing. We focus our work mainly on convergent routing towards base station. [TAG] aims to provide a high level declarative interface for querying the sensor readings in real time. Though it can be used for reliable data collection as well, we believe it is too complex if the primary goal is only to gather all the readings for offline analysis. [Tric] and [PSFQ] are reliable data dissemination protocols used for retasking the network that exploit the broadcast nature of wireless communication. [RMST] explores where to fit the reliable transport in the sensornet architecture.
Approach
Our design is at an early stage. We look at the problem as a distributed replication problem. Primary copies of each sensor reading log will be initially at the originating mote. Sensor reading logs will be packed in packets with unique sequence numbers/ids. Packets will be transmitted in batches, hop by hop to multiple neighboring motes in the upstream towards the base station. The base station will eventually get the packets and send acknowledgements to the owner mote. A mote can delete acknowledged logs and reuse the storage for further sensor readings. We are investigating a) transfer of ownership of logs b) using bloom filters for summarizing acknowledgements c) possible ideas from scalable incast protocols. Though it can be argued that hop by hop store-and-forward might waste storage at other motes, we believe it will help reduce routing overheads.
Timeline
Here is our tentative plan
Oct 31st – Flesh out a detailed design and start implementing simulation using TOSSIM
Nov 15th – Analyze first cut simulation results, make improvements to design.
Dec 1st – Final analysis and writeup.
References
[Civi] Multi-Purpose Wireless Accelerometers for Civil Infrastructure Monitoring, Shamim N. Pakzad, Sukun Kim, Gregory L Fenves, Steven D. Glaser, David E. Culler, and James W. Demmel, the Proceedings of the 5th International Workshop on Structural Health Monitoring (IWSHM 2005), Stanford, CA, September 2005
[Habi] Wireless Sensor Networks for Habitat Monitoring.
Alan Mainwaring, Joseph Polastre, Robert Szewczyk, David Culler, John Anderson.
In the 2002 ACM International Workshop on Wireless Sensor Networks and Applications. WSNA '02, Atlanta GA, September 28, 2002. (also Intel Research, IRB-TR-02-006)
[Kim] Reliable Transfer on Wireless Sensor Networks, Sukun Kim, Rodrigo Fonseca, and David Culler, The First IEEE International Conference on Sensor and Ad hoc Communications and Networks (SECON 2004), Santa Clara, CA, October 2004
[Tric] P. Levis, N. Patel, D. Culler, and S. Shenker, “Trickle: A self-regulating
algorithm for code maintenance and propagation in wireless sensor
networks,” in First USENIX/ACM Symposium on Network Systems
Design and Implementation (NSDI), 2004.
[TAG] S. R. Madden, M. J. Franklin, J. M. Hellerstein, and W. Hong, “TAG: a
Tiny AGgregation Service for Ad-Hoc Sensor Networks,” in Proceedings
of the ACM Symposium on Operating System Design and Implementation
(OSDI), Dec. 2002
[PSFQ] C.-Y. Wan, A. T. Campbell, and L. Krishnamurthy, “Psfq: a reliable
transport protocol for wireless sensor networks,” in Proc. of the 1st ACM
international workshop on Wireless sensor networks and applications.
ACM Press, 2002.
[RMST] F. Stann and J. Heidemann, “Rmst: Reliable data transport in sensor
networks,” in Proceedings of the First International Workshop on Sensor
Net Protocols and Applications. IEEE, April 2003, pp. 102–112.