A chirp FSK improvement for communications in shallow water using bandwidth overlapping

Underwater acoustic communications in shallow water are essential for the transmission of data between AUVs and remote sensors. Shallow water communications remain a challenge due to factors like multipath propagation, time variations of the channel, small available bandwidth and strong signal attenuation. To adress this problem, we propose a new chirp FSK scheme that enhances the data rate and is robust to noise. Using Gabor chirp spectra linear combination to describe the transmitted symbol and overlapping bandwidth, we obtain simulated transmissions at a peak data rate of 7 kbits/sec. Furthermore, simulation results reveal a very low bit error rate even with a low signal-to-noise ratio indicating that long ranges could be reached.