Toward Massive Satellite Signals of Opportunity Positioning: Challenges, Methods, and Experiments

Satellite signals of opportunity positioning (SSOOP) attempts to work out a navigation solution with many non-global navigation satellite systems (GNSS) satellite signals, when GNSS signals are not available. It is promising in addressing GNSS vulnerability by using an overwhelming quantity of satellites with diverse signal formats, multiple radio bands, and global availability. How to figure out an applicable receiver position from the signals transmitted by anonymous satellites with unknown emission time? Toward massive SSOOP, this work contributes (a) a summary of the fundamental challenges by reviewing the mathematical formulations of SSOOP problem; (b) a set of proposed methods for SSOOP, including orbit predication, signal processing, and different modes of user positioning; (c) an analysis on the orbit prediction precision of two-line elements (TLEs) at different geographic locations on Earth and its impact on positioning performance, based on the orbit data obtained from our experimental (international ID: 40136) satellite that has a similar orbit height as the IRIDIUM satellites; and (d) the design and test result of an IRIDIUM SSOOP receiver prototype for verifying the proposed methods and corroborating the analysis, which showed a CEP ≈892 m (circular error probable) in standalone mode tests and a CEP ≈40 m in differential mode tests.