Time-Domain-Optimized Antenna Array for High-Precision IR-UWB Localization in Harsh Urban Shipping Environments

Urban freight distribution via inland waterways is an important way to boost the quality of life in major urban areas with dense water networks. Cost-effective autonomous pallet shuttle barges (PSBs) are key to accelerate the shift from road-based transport to inland waterways. Yet, the urban settings impede reliable centimeter-level localization at critical waterway sections. In this article, we propose a time-domain-optimized antenna array to provide high-precision 3-D localization in these complex environments with minimal shore-side infrastructure by exploiting impulse-radio ultra-wideband (IR-UWB) technology. To enable joint distance and 2-D angle-of-arrival (AoA) estimation, we present a novel IR-UWB antenna element that covers channels 5 and 7 of the IEEE 802.15.4z standard, serving as a building block for scalable multi-antenna systems. By leveraging the air-filled substrate-integrated-waveguide (AFSIW) technology and adopting a multi-objective system-level optimization strategy, excellent performance is reconciled with a compact footprint and cost-effective fabrication. The 3-D positioning accuracy of a 2 x 2 array is evaluated in stand-alone conditions and when installed on a metal plate mimicking a PSB's metal hull, showing that all distance errors and 97% of angular errors remain below 2 cm and 5 degrees, respectively. Finally, three anchor nodes, each consisting of a 1 x 4 array connected to a Pozyx hardware platform, are installed on a vessel navigating in a narrow canal below a bridge in Ghent. With only one shore-side UWB beacon node deployed, 96% of AoA estimation errors remain below 10 degrees, while the distance error remains below 10 cm, proving good installed performance in harsh urban shipping environments.