Self-Configurable Positioning Technique for Multi-hop Wireless Networks To appear in IEEE Transaction on Networking Chong Wang Center of Advanced Computer Studies University of Louisiana at Lafayette

Introduction Geographic location information – Reduce routing overhead – Improve scalability – Intelligent coordination Global vs. local positioning Our goal – Self-configurability – Robustness – High accuracy

Related Work Global Positioning Techniques –Global Positioning System (GPS[1]) –Signpost Navigation System –Global Navigation Satellite System –Cellular Geolocation System –Drawbacks: hardware, signal obstruction Local Positioning Techniques – GPS-free positioning [2] Not robust – Connectivity-based positioning [4] Inaccurate – GPS-less [3], Fine-grain [6], APS [5] Convex[9], Recursive [10] Not self-configurable

Euclidean Distance Estimation Crucial for positioning Proposed scheme –Given node distribution (a) (b) Fig. 1. The Euclidean distance estimation model.

Euclidean Distance Estimation (2) First hop – within Ss range & closest to D – s coordinates where – 1-hop length Shortest path length – Apply 1-hop estimation recursively – Total path length

Coordinates Establishment Two steps: landmarks & regular nodes Landmarks –Estimate distance to each other –Exchange distance information –Define error function –Minimize by using Simplex method where

Coordinates Establishment (2) Regular nodes – May be considered as landmarks, but not scalable – Estimate dist. to landmarks – Define error function – Minimize p A B C D A B C D LABLAB L CD L BC L AD LACLAC LBDLBD p (a)(b)

Selection of Landmarks Number of landmarks –The more landmarks, the higher the accuracy. Location of landmarks –Separated as far as possible Algorithm of identifying corner nodes –Degree of center:

Cont

Simulation And Discussion Simulation Model – Simulator: Matlab – Variable parameters – Number of nodes: 50 – 400 – Number of landmarks: 3 – 8 – Measurement inaccuracy: 0 – 40% – Performance criteria – Coordinates error – Computing time

Examples GPS tuning N=50, no translationN=100, no translationN=400, no translation N=50, center matchN=100, center matchN=400, center match N=50, GPS tuningN=100, GPS tuningN=400, GPS tuning

with node density Impact of measurement error Accuracy with more landmarksDelay with more landmarks Simulation And Discussion

Conclusion We have proposed a self-configurable positioning technique for multi-hop wireless networks. The proposed positioning technique is self-configurable and independent of global position information. The coordinates error is determined by node density, one-hop distance measurement inaccuracy, and the number of landmarks. The computing time for coordinates establishment is in the order of milliseconds, which can be accepted by most applications in the mobile ad hoc networks as well as the sensor networks.

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