Analytical Modeling of Latency and Energy Trade-offs in FiRa-Like BLE-UWB Ranging and Localization Systems
Accurate position and distance information provided by Ultra-Wideband (UWB) can enhance a wide range of applications. However, its receive-mode power consumption makes continuous channel monitoring impractical for energy-constrained devices. Consequently, UWB systems often rely on Bluetooth Low Energy (BLE) to discover peers and establish sessions before ranging begins. Although both technologies have been studied in isolation, an framework capturing the latency and energy consumption of the complete workflow is still lacking. To address this gap, we develop a unified analytical model for BLE-assisted UWB systems, from device-to-device ranging to infrastructure-based localization. The model includes closed-form expressions for discovery, parameter exchange, and ranging, and evaluates the resulting latency and energy consumption. Evaluation of three representative BLE configurations shows that the scanner consumes 28-57x more energy per discovery than the advertiser. In addition, the 99th-percentile discovery latency is 2-3.4x higher than the mean and reaches up to 110 s in the lowest-power configuration. The one-time BLE setup overhead is amortized after 24-562 ranging rounds, depending on the discovery configuration. Overall, the analysis demonstrates that the BLE discovery phase can dominate both the latency and the energy budget during short UWB interactions, making discovery configuration as important as the ranging scheme.