Robust Node Localization for Wireless Sensor Networks - CiteSeerX

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Localization Success (%)1007550250GPS Spotlight Centroid DV-Hop RobustLocalizationLocalization SystemFigure 5: Localization Error.15,000Localization Error (feet)Figure 3: Robust Localization Case Study.2520151050GPS Spotlight Centroid DV-Hop RobustLocalizationLocalization SystemFigure 4: Localization Error.sight. In addition, any node that is not positioned in thewooded area has a 15% probability of not having a line ofsight with satellites or aerial vehicles (and hence, can not belocalized through GPS or Spotlight).The experimental results of 10 simulations with randomseeds are shown in Figure 4, Figure 5 and Figure 6. Asshown in Figure 4 Spotlight and GPS have the highest accuracies(2-5ft), but they fail to localize all the nodes in thesensor network. On the other hand, DV-Hop localizes theentire network (as shown in Figure 5), but the accuracy islow (16 ft average localization error). The Centroid schemehas also a low accuracy and it fails to localize the entire network,as shown in Figure 5, due to the low number of anchornodes (we assumed 10% anchors). The Robust Localizationscheme, however, successfully localizes the entire WSN andhas an average localization error of about 7ft. Even thoughindividual node localization schemes fail (GPS fails for 90%of nodes and Spotlight fails for 50% of nodes), the Robustsolution localizes all sensor nodes with a good average localizationaccuracy.The price paid for achieving a higher accuracy than individualcomponents is shown in Figure 6 - the overhead(we consider only communication overhead). While GPSand Spotlight have no communication overhead, the RobustLocalization scheme has a higher overhead than Centroid,but lower than DV-Hop, which requires a flooding of the entirenetwork (the modified implementation of DV-Hop thatthe Robust Localization framework uses, does not need toflood the entire network). We consider the overhead relativelymodest, when considering the obtained accuracy innode location.Overhead (# Packets)12,0009,0006,0003,0000GPS Spotlight Centroid DV-Hop RobustLocalizationLocalization SystemFigure 6: Localization Protocol Overhead.4. FUTURE DIRECTIONSThe proposed localization framework is just a small partof the more complete solution that will allow a non-expertto build a robust and efficient localization system for a particularWSN deployment. We envision several areas thatrequire further research:• Develop higher level abstractions for composing localizationprotocols. Our current implementation for theLocalization Manager is done by hand. We aim to providea programming tool (with a script-like language)for building a localization system from individual localizationprotocols.• Develop an analysis tool that evaluates the correctnessof a hierarchical localization framework and, possibly,gives soft-guarantees (e.g., largest expected localizationerror and the overhead required to achieve it).• Consider a broader set of existing localization schemesand see how well they are accommodated by our framework.• How to optimize the simultaneous execution of protocolsthat use, for example, radio communication?Instead of having each protocol send/receive its ownmessages, an aggregation of data contained in thesemessages may significantly reduce the communicationoverhead.• Could a sensor node be able to evaluate the accuracy ofits location estimate and how? This could be a betterindicator for stopping the node from executing subsequentlocalization schemes, than the currently proposeddesign.• Analysis of robustness against malicious attacks. Dueto localization protocol multi-modality, it is more difficultfor an attacker to compromise the integrity of thenode localization service.51
5. RELATED WORKProtocol composition has been frequently obtained by layeringprotocols vertically, in stacks. Horus [16], for example,is based on a vertical stack of protocols, where theevents are strictly passed from one layer to the adjacentone. A non-hierarchical protocol composition framework isJGroup/ARM [7]. It introduces the concept of a dependencygraph among protocols/layers (graph obtained by each layerregistering its interest in other layers). Our work has similaritieswith HLS [12] (which proposes a hierarchical frameworkfor composing soft real-time schedulers) and [3] (whichuses sensing multi-modality for robust localization). In thispaper, however, we propose for the first time to provide robustnessfor node localization through protocol composition.This allows us to overcome the situation when a individualprotocol fails (due to its assumptions) through a successfulexecution of a different localization protocol.6. CONCLUSIONSThe problem of robust, practical, node localization inWSN remains an important open research problem. In thispaper we argue that the existing solutions for node localizationcan be efficiently used by the proposed frameworkto ensure a high accuracy at a low cost. Our simulationresults support our claims by showing an average reductionin localization error of 50% when compared to individual localizationschemes. Our framework proposes a new researchdirection for robust node localization in WSN: localizationprotocol multi-modality.7. ACKNOWLEDGMENTSThis work was supported by the ARO grant W911NF-06-1-0204, by the DARPA grant F336616-01-C-1905, and bythe NSF grant CNS-0614870. We would like to thank theanonymous reviewers for their valuable feedback.ad hoc sensor network. In Proceedings of InternationalConference on Information Processing in SensorNetworks (IPSN), 2003.[9] D. Niculescu and B. Nath. DV-based positioning inadhoc networks. Telecommunication Systems, 2003.[10] B. Parkinson and J. Spilker. Global positioningsystem: theory and applications. Progress inAeronautics and Astronautics, 1996.[11] N. Priyantha, A. Chakraborty, and H. Balakrishnan.The cricket compass for context-aware mobileapplications. In Proceedings of InternationalConference on Mobile Computing and Networking(MobiCom), 2001.[12] J. Regehr and J. A. Stankovic. HLS: A framework forcomposing soft real-time schedulers. In Proceedings ofIEEE Real Time Systems Symposium (RTSS), 2001.[13] A. Savvides, C. Han, and M. Srivastava. Dynamicfine-grained localization in ad-hoc networks of sensors.In Proceedings of International Conference on MobileComputing and Networking (MobiCom), 2001.[14] Y. Shang, W. Ruml, Y. Zhang, and M. P. J.Fromherz. Localization from mere connectivity. InProceedings of ACM Symposium on Mobile Ad HocNetworking and Computing (MobiHoc), 2003.[15] R. Stoleru, T. He, J. A. Stankovic, and D. Luebke. Ahigh-accuracy low-cost localization system for wirelesssensor networks. In Proceedings of ACM Conferenceon Embedded Networked Sensor Systems (SenSys),2005.[16] R. van Renesse, K. P. Birman, R. Friedman,M. Hayden, and D. A. Karr. A framework for protocolcomposition in Horus. In Principles of DistributedComputing, 1995.8. REFERENCES[1] N. Bulusu, J. Heidemann, and D. Estrin. GPS-less lowcost outdoor localization for very small devices. IEEEPersonal Communications Magazine, October 2000.[2] L. Doherty, K. Pister, and L. Ghaoui. Convex positionestimation in wireless sensor networks. In Proceedingsof IEEE Conference on Computer Communications(INFOCOM), 2001.[3] L. Girod and D. Estrin. Robust range estimationusing acoustic and multimodal sensing. In Proceedingsof IEEE/IRJ International Conference on IntelligentRobots and Systems (IROS), 2001.[4] T. He, C. Huang, B. Blum, J. A. Stankovic, andT. Abdelzaher. Range-Free localization schemes inlarge scale sensor networks. In Proceedings of ACMInternational Conference on Mobile Computing andNetworking (MobiCom), 2003.[5] L. Lazos and R. Poovendran. SeRLoc: Securerange-independent localization for wireless sensornetworks. In Proceedings of ACM Workshop onWireless Security (WiSe), 2004.[6] M. Maroti, B. Kusy, G. Balogh, P. Volgyesi, A. Nadas,K. Molnar, S. Dora, and A. Ledeczi. Radiointerferometric geolocation. In Proceedings of ACMConference on Embedded Networked Sensor Systems(SenSys), 2005.[7] H. Meling. Non-hierarchical dynamic protocolcomposition in Jgroup/ARM. In Proceedings of NorskInformatikkonferanse, 2006.[8] R. Nagpal, H. Shrobe, and J. Bachrach. Organizing aglobal coordinate system from local information on an52
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