A Practical Evaluation of Forward Error Correction Schemes and PSK Detection Parameters for Underwater Acoustic Transmissions

In comparison to traditional wired and wireless communication scenarios, the underwater channel is peculiar, being significantly more difficult to communicate in and presenting a unique set of features and impairments, thus necessitating special care in selecting ad hoc encoding and modulation technologies to achieve successful transmissions. This paper presents the optimization work carried out on the digital signal processing (DSP) section of the software that runs on the SuM modem, an underwater acoustic software-defined modem (SDM) developed by SubSeaPulse Srl. In particular, this document will cover potential improvements of the Flexframe framing structure by Liquid DSP, used by the modem for phase-shift-keying (PSK) communication, focusing on the analysis of two parameters: the Samples-Per-Symbol (SPS) value and the Forward-Error-Correction (FEC) schemes used. Final results show that a noticeable degree of improvement can be achieved and open new perspectives for further research and implementation.