Quadrature Acoustic Frequency Combs Multiplexing for Massive Parallel Underwater Acoustic Communications

Abstract

Underwater acoustic (UWA) communication has been developing rapidly over the past decades for its crucial position in resource exploration, environmental monitoring, and scientific research. However, the transmission data rate of UWA communication is limited by the narrow bandwidth of the underwater acoustic channel. Here, the generation of quadrature acoustic frequency combs (AFCs) is first reported. Massive parallel channels achieved with multiplexing of AFCs for UWA communication are demonstrated. The generated AFCs have unique characteristics which have a stable and precise division in frequency and time domain simultaneously with carrier spacing of 1 Hz with the stability of 10 −8 . The different frequency spacing in combs leads to different teeth spacings in time, which is orthogonal and separable in the time domain. The orthogonality among AFCs provides a new dimension for multiplexing and can drastically increase channel efficiency. The underwater acoustic communication experiments demonstrate that it is drastically increasing the transmission rate to 45.33 kb s −1 and high spectral efficiency of 1.51 (channel s −1 ) Hz −1 without utilizing other modulation techniques by a single transducer. Since AFCs multiplexing is a completely independent degree of freedom that can be readily integrated with other high order modulation techniques, such as quadrature amplitude modulation and phase-shift keying, in a single channel, AFCs multiplexing opens a new dimension for acoustic communication.

Biomechanical Sensing Using Gas Bubbles Oscillations in Liquids and Adjacent Technologies: Theory and Practical Applications

“…However, despite an immense success of OFC in both academic and commercial research settings, it has been realised that any OFC technology has a number of drawbacks that originate from fundamental physical limits of light. For example, this is the case in underwater communication [ 176 , 177 , 178 ] and in some medical imaging and sensing technologies used deeply inside a living human body [ 35 , 36 ], where the intensity of light is significantly attenuated due to scattering and optical absorption in body tissues. This situation has motivated development of alternative approaches exploiting the well-established fact that optical waves share many fundamental physical properties with sound waves [ 162 ].…”

Effects of High-Order Nonlinearities on Phononic Frequency Combs

“…PFC has also been generated in optomechanical [23], magnetomechanical [24][25] and electromechanical systems [26]. Besides multiple experimental observations, PFC has also been applied in underwater imaging [27][28] and energy harvesting [29][30]. As a matter of fact, there have been a number of patents granted on various PFC technologies [31][32][33][34][35][36].…”

Biomechanical Sensing using Gas Bubbles Oscillations in Liquids and Adjacent Technologies: Theory and Practical Applications

“…We will continue this discussion in Sec. 4.3 this is the case in underwater communication [176][177][178] and in some medical imaging 573 and sensing technologies used deeply inside a living human body [35,36], where the 574 intensity of light is significantly attenuated due to scattering and optical absorption in 575 body tissues. This situation has motivated development of alternative approaches that 576 exploit the well-established fact that optical waves share many fundamental physical 577 properties with sound waves [162].…”