Pioneering time-of-arrival localization with cable-free and battery-free transponders

Abstract

In traditional underwater acoustic positioning methods, reliance on systems such as Long Baseline (LBL) and Short Baseline (SBL) localization utilize transponders that actively transmit acoustic pulses. These systems are typically powered by cables and often result in constrictive deployment. The adoption of cable-free and battery-free transponders can greatly enhance the flexibility of deployment. This change facilitates large-scale implementation, thereby providing precise positioning services across extensive areas. However, localization with passive transponders faces unique challenges. It has been widely accepted that battery-free nodes are unsuitable for time-of-arrival (ToA) localization. The primary reason is the wakeup delay varies based on location and environment, which introduces an unpredictable offset into the time lapse between the transmitted and received pulses. To overcome this challenge, we model the wakeup delay of passive node, considering the hardware characteristics of the passive node and the multipath acoustic channel. Moreover, we propose a ToA-based localization framework specifically tailored for battery-free transponders. In this paper, we will verify our wakeup delay model and assess the performance of the proposed localization method through experimental results. This new approach marks a significant departure from the existing effort, making localization with passive transponders feasible.