Esmaiel Hamada, Sun Haixin
Department of Information and Communication, School of Informatics, Xiamen University, Xiamen 361005, China.
Electrical Engineering Department, Faculty of Engineering, Aswan University, Aswan 81542, Egypt.
Sensors (Basel). 2022 Aug 1;22(15):5751. doi: 10.3390/s22155751.
Non-orthogonal multiple access (NOMA) is considered a promising multiple access technique for fifth generation (5G) mobile networks and tactical internet due to its high spectral efficiency. Thanks to the high spectral efficiency of NOMA, it can be a strong candidate suitable for the limited channel bandwidth of underwater acoustic communication. The NOMA transmitter is employing superposition coding (SC). The NOMA receiver is based on the successive interference cancellation (SIC) technique. The multicarrier NOMA adopts orthogonal frequency division multiplexing (OFDM) as a multicarrier modulation (MCM) technique; however, conventional cyclic prefix OFDM (CP-OFDM) and zero padding (ZP-OFDM) have inefficient spectral efficiency. Thanks to efficient synchronization and high energy-spectral efficiency of the time-division synchronization OFDM (TDS-OFDM), it is a significant attractive candidate for underwater multicarrier communication. However, wasting the power transmission of long guard intervals in the battery-based underwater communication is represented as one of the TDS-OFDM main drawbacks. Harvesting energy and improving the energy efficiency of acoustic-based TDS-OFDM-NOMA represent high achievement goal battery recharging challenges due to the ocean environment. This paper proposes time switching simultaneous wireless information and power transfer (TS-SWIPT) to harvest the energy of transmitted power over the guard interval in the TDS-OFDM-NOMA scheme. The proposed energy harvested scheme harvests the energy from the wasted power in the long guard interval and improves the energy efficiency of the TDS-OFDM multicarrier scheme. This study demonstrates the superiority of the proposed TDS-OFDM-NOMA over the underwater acoustic channel by revealing high energy efficiency, high spectral efficiency, better bit error rate performance, and high system data throughput.
非正交多址接入（NOMA）因其高频谱效率，被认为是适用于第五代（5G）移动网络和战术互联网的一种很有前景的多址接入技术。得益于NOMA的高频谱效率，它可能是适合水下声学通信有限信道带宽的有力候选技术。NOMA发射机采用叠加编码（SC）。NOMA接收机基于连续干扰消除（SIC）技术。多载波NOMA采用正交频分复用（OFDM）作为多载波调制（MCM）技术；然而，传统的循环前缀OFDM（CP - OFDM）和零填充（ZP - OFDM）频谱效率较低。得益于时分同步OFDM（TDS - OFDM）的高效同步和高能谱效率，它是水下多载波通信极具吸引力的候选技术。然而，在基于电池的水下通信中，长保护间隔的功率传输浪费是TDS - OFDM的主要缺点之一。由于海洋环境，收集能量并提高基于声学的TDS - OFDM - NOMA的能量效率是电池充电面临的重大挑战。本文提出了时分切换同时无线信息与功率传输（TS - SWIPT），以在TDS - OFDM - NOMA方案的保护间隔内收集发射功率的能量。所提出的能量收集方案从长保护间隔中的浪费功率中收集能量，并提高了TDS - OFDM多载波方案的能量效率。本研究通过揭示高能效、高频谱效率、更好的误码率性能和高系统数据吞吐量，证明了所提出的TDS - OFDM - NOMA在水下声学信道上的优越性。
