Communications and Signal Processing Lab, Telecommunication Research Institute (TELMA), ETS Ingeniería de Telecomunicación, Universidad de Málaga, 29010 Málaga, Spain.
Sensors (Basel). 2022 Aug 29;22(17):6514. doi: 10.3390/s22176514.
The purpose of this work is to present a flexible system that supports the study of wideband underwater acoustic communications (UAC). It has been developed both to measure channels and to test transmission techniques under realistic conditions in the ultrasonic band. This platform consists of a hardware (HW) part that includes multiple hydrophones, projectors, analog front-ends, acquisition boards, and computers, and a software (SW) part for the generation, reception, and management of acoustic sounding signals and noise. UAC channels are among the most hostile ones and exhibit an important attenuation and distortion, essentially due to both multipath propagation, which results in a very long channel impulse response, and time-varying behavior, which produces a notable Doppler spread. To cope with this challenging medium, sophisticated transmission techniques must be employed. In this sense, adequate signal processing algorithms have been designed aiming not only at the analysis and characterization of underwater communication channels but also at the evaluation of diverse modulation, detection, and coding schemes, from Orthogonal Frequency Division Multiplexing (OFDM) to single-carrier digital modulations with a single-input multiple-output (SIMO) configuration that takes advantage of diversity techniques. Wideband sounding signals, to be injected into the sea from the transmitter side, are created with patterns that allow multiple tests on a batch. With offline processing of the captured data at the receiver side, different trials can be carried out in a very flexible manner. The different aspects of the platform are described in detail: the HW equipment used, the SW interface to control acquisition boards, and the signal processing algorithms to estimate the UAC channel response. The platform allows the analysis and design of new proposals for underwater communications systems that improve the performance of the current ones.
本工作旨在提出一个灵活的系统，支持对宽带水下声通信 (UAC) 的研究。它既被开发用于测量信道，也被开发用于在超声带的实际条件下测试传输技术。该平台由硬件 (HW) 部分和软件 (SW) 部分组成，HW 部分包括多个水听器、发射器、模拟前端、采集板和计算机，SW 部分用于生成、接收和管理声探测信号和噪声。UAC 信道是最具挑战性的信道之一，表现出重要的衰减和失真，这主要是由于多径传播导致的非常长的信道冲激响应，以及时变行为导致的显著多普勒扩展。为了应对这个具有挑战性的媒介，必须采用复杂的传输技术。从这个意义上说，已经设计了适当的信号处理算法，旨在不仅分析和表征水下通信信道，还评估各种调制、检测和编码方案，从正交频分复用 (OFDM) 到利用分集技术的具有单输入多输出 (SIMO) 配置的单载波数字调制。要从发射器侧注入到海中的宽带探测信号是使用允许批量进行多次测试的模式创建的。通过在接收器侧对捕获数据进行离线处理，可以非常灵活地进行不同的试验。平台的不同方面都进行了详细描述：使用的 HW 设备、用于控制采集板的 SW 接口以及用于估计 UAC 信道响应的信号处理算法。该平台允许对水下通信系统的新提案进行分析和设计，以提高现有系统的性能。
