The observability analysis of a collaborative opportunistic navigation (COpNav) environment whose states may be partially-known is considered. A COpNav environment can be thought of as a radio frequency signal landscape within which one or more radio frequency receivers locate themselves in space and time by extracting and possibly sharing information from ambient signals of opportunity (SOPs). Such receivers, whether vehicle-mounted or integrated into hand- held devices, exploit signal diversity to improve navigation and timing robustness compared to stand-alone Global Positioning System (GPS) receivers in deep urban, indoor, or otherwise GPS-hostile environments. Available SOPs may have a fully-known, partially-known, or unknown characterization. In the present work, the receivers are assumed to draw only pseudorange-type measurements from the SOPs. Separate observations are fused to produce an estimate of each receiver’s position, velocity, and time (PVT). Since not all SOP states in the COpNav environment may be known a priori, the receivers must estimate the unknown SOP states of interest simultaneously with their own PVT. This paper establishes the minimal conditions under which a COpNav environment consisting of multiple receivers and multiple SOPs is completely observable. Moreover, in scenarios where the COpNav environment is unobservable, the unobservable directions in the state space are specified. Simulation and experimental results are presented to confirm the theoretical observability conditions.

Cite and download the paper:
Z.M. Kassas and T.E. Humphreys, "Observability Analysis of Collaborative Opportunistic Navigation with Pseudorange Measurements," IEEE Intelligent Transportation Systems, 15(1): 260-273, 2014.