Abstract
In this paper, we propose underwater acoustic (UWA) communications using a generalized sinusoidal frequency modulation (GSFM) waveform, which has a distinct ambiguity function (AF) and correlation function characteristic. For these reasons, it is more robust in multipath channels than the conventional chirp spread spectrum (CSS) with a linear frequency modulation (LFM) waveform. Four types of GSFM waveforms that are orthogonal to each other are applied for each symbol in the proposed method. To evaluate the performance of the proposed method, we compared the performances of the proposed method and conventional method by conducting diverse experiments: simulations, lake trials and sea trials. In the simulation results, the proposed method shows better performance than the conventional method. The lake trial was conducted with a distance of 300~400 m between the transmitter and receiver. As a result of the experiment, the average bit error rate (BER) of the proposed method is and that of the conventional method is , which shows that the proposed method is superior to the conventional method. The sea trial was conducted at a distance of approximately 20 km between the transmitter and receiver at a depth of 1500 m, and the receiver was composed of 16 vertical line arrays (VLAs) with a hydrophone. The proposed method had a BER of in one channel and was error free in the other.
Highlights
We proposed underwater acoustic (UWA) communication using generalized sinusoidal frequency modulation (GSFM) waveforms, which
We proposed UWA communication using GSFM waveforms, which offers advantageous modulation in a fluctuating UWA channel, and the proposed offers advantageous modulation in a fluctuating UWA channel, and the proposed method’s method’s performance was demonstrated by a comparison with that of the conventional performance was demonstrated by a comparison with that of the conventional chirp spread spectrum (CSS) method
According to the ambiguity function (AF) and ACF, we demonstrated that the GSFM waveform
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. AquaSeNT provides a UWA communication modem using orthogonal frequency division multiplexing (OFDM) technology. Designing GSFM waveforms with different parameter values (determined by the user) can produce a family of waveforms that occupy the same band of frequencies and are nearly orthogonal to each other [15] For this reason, the GSFM waveform was recently researched in active sonar by Hague and Buck [16]. Its characteristics are demonstrated using the AF and correlation in this paper Using this orthogonality of each waveform and distinct mainlobe regions in the AF and ACF, we expect robustness in the ISI-generated multipath channel. The conventional CSS method is divided into two bands to match the data rate and time bandwidth product with the GSFM method.
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