Underwater acoustic communication using orthogonal signal division multiplexing with windowing

Abstract

Underwater acoustic (UWA) communication is an essential technology that supports underwater surveys by transmitting images and movies wirelessly. However, UWA communication is still challenging due to the large delay and Doppler spreads in UWA channels. Doppler-resilient orthogonal signal division multiplexing (D-OSDM) under water has been found effective in such channels, but Doppler modeling errors prevent further improvement in communication quality. In this paper, we clarify the effect of Doppler modeling errors on the communication quality of D-OSDM and propose the use of a window function in D-OSDM to address the issues that such errors raise. We also evaluate the communication quality of D-OSDM using the window function through simulations and experiments. The experimental results show a 56% increase in the number of error-free data blocks, indicating that windowing can improve communication quality.

Detection of fish passing through a narrow path using reflected and transmitted ultrasonic waves

“…Low frequency ultrasound is generally used in ocean acoustics, to cope with the attenuation that occurs in the water. [14][15][16][17][18] The focus has generally been on the echoes obtained from the swim bladders of fish, because 90% of the echoes from fish when using low frequency ultrasound come from the swim bladder. 19) Megahertz-band ultrasound has been used for high-resolution measurements in other areas of research, such as nondestructive evaluation [20][21][22] and biomedical ultrasound applications.…”

Improvement of communication quality using compressed sensing in underwater acoustic communication system with orthogonal signal division multiplexing

“…Simulation environment. 48) water. The reflection coefficients of the sea surface and sea bottom are −1 and 0.178, respectively.…”

“…Compressed sensing that solves simultaneous equations by exploiting the sparse nature of sparse signals has a potential to improve OSDM communication quality. 48) Specifically, compressed sensing solves the sparsity of a linear system by combining L1 regularization (promoting a sparse solution) and L2 regularization (LS) with certain gain. Although the use of compressed sensing has been found to improve the performance of single-carrier and multi-carrier systems, [49][50][51] it has not been utilized in OSDM.…”

“…Fig.5. (Color online) Relationship between standard deviation σ and optimal τ that achieves the smallest BER 48). …”

Simultaneous distance measurement and information transmission in mobile environment using digital acoustic communication

“…In underwater acoustic communication using OSDM, sidelobes can be suppressed by applying a window function. 35) Therefore, in this paper, we also suppress sidelobes by applying a Hanning window to the received signal. (2) Frequency conversion and sampling: The receiver records the signal y(t), converts the received signal frequency to baseband, and obtains the received sequence y.…”