A Janus compatible software-defined underwater acoustic multiple-input multiple-output modem

Abstract

This article describes the implementation of a multiple-input multiple-output acoustic communication link in shallow water conditions to enable a software-defined acoustic modem with a maximum transmission rate of 20 kbps in a 5-kHz bandwidth. The reliability improvement of a low-complexity Alamouti space–time block code is evaluated to improve the diversity in a high-rate transmission mode using single carrier modulation, as well as in a low-rate transmission mode relying on continuous-phase frequency-shift keying. Using measurements in realistic subsea conditions, the effect of the spatial channel correlation is demonstrated. It is found that for the space–time block code/continuous-phase frequency-shift keying, the spatial diversity is significantly degraded due to the high spatial correlation. In contrast, for the high-mode transmission rate, space–time block code with single carrier modulation offers a bit error rate improvement by a factor over hundred, in comparison to a single transmit element, demonstrating that the multiple-input multiple-output optimal code depends on the software-defined acoustic modem transmission mode.

Underwater Multi-Channel MAC with Cognitive Acoustics for Distributed Underwater Acoustic Networks

“…In this scenario, i tx = M Data (5,1) = 5, which is consistent with the case when FI = 5 and SFI = 1. This indicates that even when x > N, the fifth CU is designed to have transmission opportunities in two subframes, SFI = [1,11].…”

“…Underwater acoustic communication stands out as a reliable wireless technology for transmitting data over extensive distances, ranging from hundreds of meters to tens of kilometers [1,2]. This advantage makes it indispensable for a variety of underwater applications including scientific observation, the exploitation of ocean resources, disaster detection, military surveillance, leisure activities, and subsea construction [3,4].…”

Underwater acoustic sensor networks: Taxonomy on applications, architectures, localization methods, deployment techniques, routing techniques, and threats: A systematic review

“…Introduce some innovative techniques to save CPU run‐time. Singh et al 32 integrated a code‐building method in a downlink, which is both a multi‐user communication system and a polar communication system. The polar code has a unique coding rate compared to other commonly used codes.…”

“…During transmission, all users may be viewed at different locations simultaneously without requiring a specialized waveguide to superimpose the signal on itself, allowing it to travel a greater distance. Singh et al 32 proposed that a reprogrammable MIMO transmitter may be utilized in an SDAM to allow an underwater communication link with a less than 1 km range in changing channel conditions. A low‐complexity Alamouti STBC is used in the firmware platform to enhance communication dependability and the likelihood of outages.…”

An Underwater Cooperative Spectrum Sharing Protocol for a Centralized Underwater Cognitive Acoustic Network

“…An acoustic frequency is considered an adequate medium for underwater wireless communications because it carries signals farther and more reliably than RF and optical frequencies [ 1 , 2 ]. Hence, underwater acoustic communications are employed in a variety of applications such as scientific observation, the exploitation of ocean resources, disaster detection, military surveillance, leisure activities, and subsea construction [ 3 , 4 , 5 ].…”