Turbo-coded frequency-hopped frequency division multiplexed signaling for underwater acoustic communications between 60 and 90 kHz in ports and very shallow waters

The underwater acoustic modem operating between 60 and 90 kHz and based on frequency-hopping frequency-division-multiplexed signaling is designed to transmit the command-and-control messages from the top-side to the wet-side in ports and very shallow waters. This paper focuses on the turbo-code design for such a system with the purpose of lowering the bit-error-rate. The error-rate performance of the coded system are measured via computer simulations. The simulation results obtained for system operations in different shallow water settings are presented and demonstrate that the acoustic downlink operates significantly more reliably using the tailored turbo-code instead of a BCH code.