Brian G. Agee, B3 Advanced Communication Systems

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Abstract:

A new approach is presented for low-latency, bandwidth-efficient, and high-precision positioning and timing of systems operating at inherent low altitude, e.g., class-1 UAS’s and ground vehicles in outdoor environments, or Industrial Internet of Thing (IIoT) devices in indoor environments. The baseline approach uses navigation signals transmitted from networks of geographically distributed beacons, to enable positioning and timing/carrier synchronization at user systems. Unlike competing beacon-based approaches, however, the signals are designed with spectral redundancy allowing their geo-observables to be estimated with precision limited by the power of those signals above the receiver noise floor, rather other co-channel beacon signals, using mature linear-algebraic techniques. Consequently, it eliminates need for time slotting or hopping to avoid intranetwork interference, greatly reducing time-to-first-fix (TTFF) for the system, and providing exceptional precision if those signals are received at high signal-to-noise ratio (SNR), regardless of their received signal-to-interference-and-noise ratio (SINR). The approach also employs a flexible multitone air interface matched to expected ranges of time-of-arrival (TOA) and frequency of-arrival (FOA) for each class of users and applications, and to efficiently meet regulatory requirements for different deployment bands. Air interfaces are described and demonstrated in areal simulations for 100 class-1 sUAS’s distributed over a 1,240 square kilometer outdoor area, and for 100 IIoT devices distributed over a three-story (9 meter), 40,000 square meter indoor facility. In sUAS scenarios, the approach demonstrates ? 10 millisecond cold-start TTFF, with 4.3 millimeter 80th percentile horizontal (XY plane) positioning accuracy and 1.4 meter 80th percentile vertical (Z-axis) positioning accuracy (50% below the 3 meter E911 Z-axis requirement), respectively, and with 20 picosecond and 15 milliHertz (6.2 ppt — sub-Stratum 1) 80th percentile timing and carrier/rate estimation accuracy, respectively. In IIoT scenarios, the approach demonstrates ? 1 millisecond cold-start TTFF, with 6.6 millimeter and 3.2 centimeter 80th percentile horizontal and vertical positioning accuracy, respectively, and with 15 picosecond and 123 milliHerz (50 ppt — sub-Stratum 2) 80th percentile timing and carrier/rate estimation accuracy.