A Low-Complexity Underwater Acoustic Coherent Communication System for Small AUV

Abstract

While underwater acoustic (UWA) communication offers a practical way to establish a wireless link with underwater vehicles, designing a UWA communication system onboard a small autonomous underwater vehicle (AUV) still poses significant challenges. As the adoption of the low-complexity, robust noncoherent communication technology is limited by low bandwidth efficiency and a low data rate, coherent UWA communication requires Doppler mitigation and channel equalization measures to achieve a relatively high data rate in a moving state. Due to the strict constraints of a small-scale AUV in terms of resources and energy consumption, it is not appropriate to use high-complexity Doppler/multipath compensation technology from the prospect of system implementation. In this paper, an efficient and low-complexity UWA differential binary phase-shift keying (DBPSK) system onboard a small AUV is proposed by simplifying the Doppler and multipath compensation. Specifically, for Doppler, the delay of the adjacent DBPSK symbols is calculated according to the Doppler estimate to facilitate delay-tuning Doppler correction. For multipath, low-complexity LMS channel equalization is incorporated with error correction coding to enable multipath mitigation. With a simple structure and low computational complexity, the proposed scheme facilitates the practical hardware implementation and system integration in the small AUV platform. The numerical simulations are conducted to assess the validity of the proposed scheme under different channel conditions and the effectiveness of the proposed scheme is further verified by two UWA communication field tests, which are performed at a practical shallow water sea and lake, respectively.

Joint Satellite-Transmitter and Ground-Receiver Digital Pre-Distortion for Active Phased Arrays in LEO Satellite Communications

“…where For the Ka-band 100 MHz signal applied in this paper, the maximum spreading of the bandwidth is 3.3 kHz. Given that the time-varying Doppler effect has been solved by mature techniques [19][20][21][22], so it is not the focus of our study. Consequently, the LEO satellite-ground transmission channel is modeled as an AWGN channel in this paper.…”

Underwater Live Video Streaming Experiment Using Radio Frequency Communication for AUVs

“…there are three main technologies used in underwater communication: (i) Acoustics communication: this is the most common and used technology for underwater communication because it can provide long-distance propagation which can be in tens of kilometers. The major drawback of this technology is the latency in communication since the transmission baud rate is only up to several kilobits per second (kbps) [3]. (ii) Wireless Optical communication: by using wireless optical communication we can achieve a data rate of hundreds of Megabits per second (Mbps) with a distance of tens of meters, this is considered the best technology for a high data rate.…”

SPACNet: A Simulation Platform of an Acoustic Cognitive Network

“…The technology of underwater acoustic networks (UAN) has drawn substantial attention due to its significant potential in extensive civil and military fields, e.g., marine environment monitoring [1], marine resource exploration [2], marine disaster warning [3], underwater information acquisition and transmission [4], autonomous underwater vehicleassisted navigation [5], communication between scuba divers [6], military applications [7], etc. Evolved from the concept of cognitive radio, the cognitive network (CN) technique has characteristics that optimize a network via environmental sensing, adaptive adjustment, intelligent decision-making, and reconfiguration.…”

“…However, while cognitive networks have achieved significant progress in academic research, the R&D of the standard network model, and practical commercial applications based on established wireless channel sensing and cognitive optimization strategies [1][2][3][4][5][6][7][8], the specific implementation of CNs in the underwater acoustic channel still encounter many difficulties due to the highly diverse channel patterns, underwater acoustic (UWA) communication modes, and network protocols.…”