Positioning Performance Limits of GNSS Meta-Signals and HO-BOC Signals
Résumé
Global Navigation Satellite Systems (GNSS) are the main source of position, navigation,
and timing (PNT) information and will be a key player in the next-generation intelligent
transportation systems and safety-critical applications, but several limitations need to be overcome
to meet the stringent performance requirements. One of the open issues is how to provide precise
PNT solutions in harsh propagation environments. Under nominal conditions, the former is typically
achieved by exploiting carrier phase information through precise positioning techniques, but these
methods are very sensitive to the quality of phase observables. Another option that is gaining
interest in the scientific community is the use of large bandwidth signals, which allow obtaining a
better baseband resolution, and therefore more precise code-based observables. Two options may
be considered: (i) high-order binary offset carrier (HO-BOC) modulations or (ii) the concept of
GNSS meta-signals. In this contribution, we assess the time-delay and phase maximum likelihood
(ML) estimation performance limits of such signals, together with the performance translation
into the position domain, considering single point positioning (SPP) and RTK solutions, being an
important missing point in the literature. A comprehensive discussion is provided on the estimators’
behavior, the corresponding ML threshold regions, the impact of good and bad satellite constellation
geometries, and final conclusions on the best candidates, which may lead to precise solutions under
harsh conditions. It is found that if the receiver is constrained by the receiver bandwidth, the best
choices are the L1-M or E6-Public Regulated Service (PRS) signals. If the receiver is able to operate at
60 MHz, it is recommended to exploit the full-bandwidth Galileo E5 signal. In terms of robustness and
performance, if the receiver can operate at 135 MHz, the best choice is to use the GNSS meta-signals
E5 + E6 or B2 + B3, which provide the best overall performances regardless of the positioning method
used, the satellite constellation geometry, or the propagation conditions.
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