MIMO-HFM: Acoustic System Design for Reliability and High Data Rate in Underwater Sensor Networks

Accomplish of reliability and high data rate over the time-varying multipath acoustic channel is very challenging. In this paper, we propose Multiple-Input and Multiple-Output (MIMO) system using Hyperbolic Frequency Modulation (HFM) waveform. Our system combines the advantages of both system, the spatial multiplexing of MIMO and Doppler-tolerance of HFM. To increase spectral efficiency, we use M-ray HFM, and overlapped sub-channel by leveraging the high temporal resolution characteristic of HFM. Also, massive operation overhead in the receiver side is drastically reduced using Fast Fourier Transform (FFT). Based on our acoustic simulator, the performance of MIMO-HFM is evaluated to show its multipath-fading resolution and Doppler-invariant. The simulation results show that the MIMO-HFM is robust in error-prone acoustic channel while increasing data rate as compared with single antenna system.