An experimental acoustic SFBC-OFDM for underwater communication

Recently underwater wireless communication has been receiving a lot of attention as it is essential to facilitate new industries and applications such as deep sea mining, ocean monitoring, submarine communication, and so on. Latest studies have showed Space-Frequency Block Code (SFBC) OFDM which was studied thoroughly in radio wireless communication is a promising candidate for underwater acoustic communication. However, currently experimental results of acoustic SFBC-OFDM in underwater environment is quite rare. In this paper, we propose a transceiver architecture of acoustic SFBC-OFDM, and show experimental results taken in Shizuoka, Japan. Additionally, we propose a method for compensating sampling rate error due to imperfection of equipment. Overall, our system consists of 2 transmitters and 4 receivers, utilizing an ultrasonic signal from 20(kHz) to 28(kHz), 160 sub-carriers, QPSK, 16QAM, 64QAM modulation, sampling speed of 96(kHz). Experimental results confirmed that our proposal system achieves 7.5 (Kbit/sec) data throughput, over more than 30(m) in vertical direction, under harsh channel conditions.