Integrated high-update-rate ultra-short baseline positioning and robust communication using underwater acoustic...

Integrated positioning and communication (IPAC) is critical for underwater unmanned platforms with severe constraints on space, power, and bandwidth. Conventional IPAC typically processes positioning and communication separately, leading to a fundamentally low positioning update rate. In this paper, we propose a receiver design for ultra-short baseline (USBL) systems that fully exploits standard direct-sequence spread-spectrum communication signals. To simultaneously support both robust communication and high-update-rate positioning, the core challenge lies in obtaining high-precision and unwrapped phase information from the modulated signal. To address this, a per-survivor processing algorithm is employed to jointly and reliably separate the transmitted bits from the phase induced by the channel. Then, a cascaded phase unwrapping method resolves the phase wrapping for each symbol across all receiving hydrophones. This process generates symbol-by-symbol unwrapped phase that enables high-accuracy and high-update-rate USBL positioning. Simulation and experimental results demonstrate that the proposed receiver achieves simultaneous USBL positioning with a nearly 20 Hz update rate and robust communication. The positioning accuracy remains consistently high and is unaffected by the modulation order, validating the method's efficacy.