Acquiring and tracking multiple frequencies across many GNSS satellites introduces computation complexity, resulting in higher power consumption. In traditional receivers, various methods are employed to select and/or reject measurements from a number of satellites and signals obtained after the tracking and data demodulation stage in the GNSS receiver. However, having a significantly large number of tracking channels does not guarantee good PNT performance coming at the cost of computation complexity and power consumption. The approach described in this paper is to develop an optimised signal selection algorithm that works in partnership with acquisition and re-acquisition, and still maintains a good PNT performance.
A relatively small but optimal list of signals and satellites may result in better performance without adding additional computation complexity load and unnecessary power loss. The objective of the proposed work is to generate an optimal list of satellites and signals and prioritise them for the receiver to track, minimising unnecessary processing. To achieve this, an optimal geometry is generated using a bootstrapping algorithm, which also introduces an innovative index to determine what to add to the satellites/signals list for prioritisation within acquisition and tracking.
To verify and validate the proposed algorithm, in an experimental data campaign, GNSS signals were collected at baseband in a dense, complex and highly dynamic multipath environment. The selected area for the experimental campaign was strategically planned because it has short-range tunnels, multiple flyovers, and high-rise buildings causing signal blockage, leading to the degradation of the navigation solution and even complete loss of lock. The data was processed using the innovative approach, the results of which were the prompt re-acquisition of services and notable reduction in re-acquisition time. Using our approach, we managed to achieve good availability of resilient PNT services with a minimum number of tracking channels being used.
