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GPS-denied Positioning using Networked communications


OBJECTIVE: Develop and demonstrate algorithms and techniques to achieve accurate absolute positioning in a GPS-denied environment using cooperatively networked sensor nodes. DESCRIPTION: The DoD is heavily dependent on the Global Positioning System (GPS) for worldwide military operations. The GPS signal, however, is subject to a variety of potential degradations, such as path loss (e.g., foliated or indoor environments), multipath (e.g., urban canyon or in-building), and interference (intentional or unintentionalthe weak GPS signal is more vulnerable than other radio links such as in a communications network). Without GPS dismounted forces must rely on alternate navigation systems such as inertial navigation systems (INS) or have no available information at all. The navigation solutions from an INS that is small enough to be carried by a soldier degenerate in under a minute to the point where the data is no longer useful. These navigation solutions are needed to support the warfighter by not only providing a navigation capability but also providing the fundamental information necessary for situational awareness on the battlefield. Navigation solutions could be enhanced by utilizing existing networked communications between several ground nodes. Dismounted forces often operate in small platoons where a communications network already exists. When some nodes lose their GPS signals, it is desirable to use the existing communications network to determine locations of such disadvantaged nodes. Unfortunately, traditional GPS-denied network positioning techniques such as Time of Arrival (TOA) or Time Difference of Arrival (TDOA) require extremely tight time synchronization among the sensor nodes; such a synchronization requirement is too stringent to be reasonably met by man-portable hardware due to SWAP constraints. Therefore, this topic seeks innovative methods to asynchronously estimate the absolute positions of those GPS-denied ground nodes by taking advantage of the existing communications network. Commercialization potential: DoD applications include tactical squads operating under foliage, indoors, or in urban conditions, as well as similarly challenged unattended sensor networks. Commercial applications include personal handheld navigation including first responder navigation inside buildings, etc. PHASE I: Develop algorithms, techniques, and a system concept for networked positioning system which overcomes adverse RF environments to allow absolute positioning and navigation to within 10 meters in a GPS-denied scenario. Demonstrate feasibility and quantify performance using analysis and simulations. PHASE II: Develop a sub-scale demonstration of a positioning network, demonstrating the ability of a group of nodes to successfully navigate under GPS-denied conditions. Evaluate the feasibility of transitioning these capabilities into realistic tactical scenarios, including network integration with military radio terminals (e.g., JTRS). PHASE III: This technology, if realized, would be of obvious immediate benefit to both DoD and commercial GPS users operating in challenging RF environments. REFERENCES: 1. Hofmann-Wellenhof B. et al. (2004). Global Positioning System: Theory and Practice. 2. Major West Kasper, May 1 2004. GPS Vulnerability Testing. GPS World. 3. Chun Yang; Thao Nguyen,"Cooperative position location with signals of opportunity", Aerospace & Electronics Conference (NAECON), Proceedings of the IEEE 2009 National, 2009, Page(s): 18 - 25.
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