PLACE: Protocol for Location And Coordinate Estimation--a wireless sensor network approach

In this paper a Protocol for Location And Coordinates Estimation (PLACE) is presented as a distributed multihop positioning approach based on wireless sensor networks without relying on GPS data at each sensor node. It is suitable for military applications where GPS services are unavailable, instable, or unreliable. PLACE conducts the positioning task in three phases: distance estimating, positioning, and refining. Issues caused by alias problems and measurement errors are discussed and solved in order to improve the practicability of the PLACE and its accuracy of the location and coordinates estimations. Simulation results comparing the PLACE approach with another popular multihop positioning approach, DV-Hop, show that (i) for the PLACE approach the average multi-hop positioning error is smaller than the corresponding one-hop range detection error and is also several magnitudes smaller than that of the DVHop; (ii) the average positioning error decreases as the average number of neighbor nodes increases in the PLACE approach while the relationship is random in the DV-Hop, which directly supports the design idea that the PLACE takes advantages of the network redundancy to improve the location estimation accuracy; and (iii) a dense wireless sensor network should be deployed when applying the PLACE for accurate location and coordinates estimations. Therefore this research contributes: (i) a distributed multi-hop positioning algorithm and an associated protocol; (ii) solutions to practical issues that increase the practicability of the multi-hop positioning approach; and (iii) investigations on relationships between network density, network scale, positionability, and positioning accuracy. Key words—Wireless sensor networks, multi-hop positioning, range estimation, GPS.