The acoustic signal transmission over the underwater channel has a limited sum rate and it consumes high power due to the properties of the underwater environment. This study attempts to use the non-orthogonal multiple access (NOMA) technologies for underwater communications. NOMA can be an attractive candidate for underwater communication due to its high spectral efficiency, resistance for carrier frequency offset, and efficient energy consumption. To cope with the hard-recharging capability of the underwater wireless sensor nodes caused by the ocean environment, this study proposes a novel transmission scheme called time-reversed NOMA (TR-NOMA) for underwater communication. In the proposed TR-NOMA, a single-input multiple-output NOMA scheme with a passive-time reversal technique is proposed to reduce the time–frequency dispersion of the underwater acoustic channels. Consequently, simultaneous wireless information and power transfer (SWIPT) can be applied for underwater TR-NOMA. In this study, a SWIPT-NOMA is postposed to harvest energy in downlink transmission from the transmitted signal. The bit error rate (BER) and the outage probability are used to characterise the performance of the proposed TR-NOMA scheme and simulation results show how the proposed TR-NOMA significantly outperforms the conventional NOMA schemes. Additionally, a mathematical framework for the average BER of TR-NOMA is delineated.

中文翻译：

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水下声学反时限NOMA的无线信息和功率传输

水下通道上的声信号传输具有有限的和速率，并且由于水下环境的特性，其消耗高功率。这项研究试图将非正交多路访问（NOMA）技术用于水下通信。由于NOMA具有高频谱效率，抗载波频率偏移和有效的能耗，它可以成为水下通信的有吸引力的候选者。为了应对由海洋环境引起的水下无线传感器节点的硬充电能力，本研究提出了一种新的传输方案，称为时间反向NOMA（TR-NOMA），用于水下通信。在拟议的TR-NOMA中，提出了一种采用被动时间反转技术的单输入多输出NOMA方案，以减少水下声通道的时频色散。因此，同时的无线信息和功率传输（SWIPT）可以应用于水下TR-NOMA。在这项研究中，SWIPT-NOMA被置于从发射信号的下行链路发射中收集能量的位置。误码率（BER）和中断概率被用来表征所提出的TR-NOMA方案的性能，仿真结果表明所提出的TR-NOMA如何显着优于常规NOMA方案。此外，还描述了TR-NOMA平均BER的数学框架。在这项研究中，SWIPT-NOMA被置于从发射信号的下行链路发射中收集能量的位置。误码率（BER）和中断概率被用来表征所提出的TR-NOMA方案的性能，仿真结果表明所提出的TR-NOMA如何显着优于常规NOMA方案。此外，还描述了TR-NOMA平均BER的数学框架。在这项研究中，SWIPT-NOMA被置于从发射信号的下行链路发射中收集能量的位置。误码率（BER）和中断概率被用来表征所提出的TR-NOMA方案的性能，仿真结果表明所提出的TR-NOMA如何显着优于常规NOMA方案。此外，还描述了TR-NOMA平均BER的数学框架。