A comparison between LoRa-inspired Chirp Spread Spectrum and Frequency Shift Keying modulations for underwater acoustic communications in snapping shrimp noise like environments

This paper provides a simulation-based comparison between LoRa-inspired Chirp Spread Spectrum (CSS) and Frequency Shift Keying (FSK) modulations. It considers CSS modulation with different Spreading Factors (SF) and FSK modulation including frequency diversity. As for the channel, additive white gaussian noise, shallow water and snapping shrimp like noise (UWAN) environments are considered. Results show that LoRa SF 7 exhibits superior robustness and achieves the lowest BER across all scenarios, outperforming both 16-FSK and 8-FSK including frequency diversity under AWGN and UWAN conditions. In frequency-selective channels for 200 m range, LoRa SF 7 provides the best performance across most of the SNR range, while at 500 m range it becomes more robust when a guard-time is introduced. The results highlight a fundamental trade-off between data rate and BER, confirming that LoRa-CSS is a suitable modulation scheme for underwater acoustic communications.