1. Key points

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A test of high-rate transmission underwater optical wireless communication was conducted in the deep sea, and a communication rate of 1 Gbps over a distance of 100 m was achieved.

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By combining Trimatiz’s original high-rate optical communication and control technology with JAMSTEC’s underwater optical technology, high-rate communication was achieved, which was several thousand times faster than conventional underwater acoustic communication and underwater optical wireless communication.

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This result is regarded as a paradigm shift in underwater wireless communication technology.

2. Overview

Senior researcher Shojiro Ishibashi, Engineering & Technology Department, Institute for Marine-Earth Exploration and Engineering (MarE3), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), and his colleagues, in collaboration with Trimatiz Ltd. (Takeshi Shimada, President & CEO, hereinafter referred to as “Trimatiz”), conducted optical wireless communication tests in the deep sea with an underwater probe and achieved high-rate underwater optical wireless communication with a communication rate of 1 Gbps (※1) over a distance of 100 m.

To date, underwater acoustic communication has utilized the mainstream wireless communication technology; however, its communication rate is only a few kbps to several tens of kbps and can be used for limited information transmission only. Recently, wireless communication technology using laser instead of acoustics for underwater communication has attracted much attention, and active research is being conducted in Japan and overseas. However, only the Mbps-level of communication rate has been achieved, and the communication distance achieved underwater was less than 100 m at a communication rate (Gbps) equivalent to that of a terrestrial communication network.

Therefore, JAMSTEC and Trimatiz have begun research to lay the basis of underwater laser communication technology that will enable high-rate communications over long distances to achieve the same level of wireless communication rate as terrestrial communication, even in an underwater environment. A 1Gbps underwater optical wireless communication system (testbed) was developed based on factors affecting the quality of underwater optical wireless communication, research on communication methods, and principles and conditions of optical systems (Fig. 1 and Table 1).

A transmitter of the 1Gbps underwater optical wireless communication system was mounted on the launcher of ROV “KAIKO,” owned by JAMSTEC. A receiver of it was mounted on the vehicle (Fig. 2). The communication test was conducted between the launcher and vehicle in the deep sea. An underwater optical wireless communication with a communication rate of 1 Gbps for a communication distance of over 100 m was achieved. This indicates that an ultra-high rate, which is unprecedented in underwater optical wireless communication, and is several thousand times more than that of conventional underwater acoustic communication (※2) and several tens of times (※3) more than that of other underwater optical wireless communication can be achieved. This technology will bring about a paradigm shift in the field of underwater wireless communication.

This research was supported by “Innovative Science and Technology Initiative for Security” Grant Number JPJ004596 implemented by the Acquisition, Technology, and Logistics Agency(ATLA), Japan.