Wave Propagation Laboratory

As 5G spreads in the latter part of the 2020s, use of wireless communication will expand as part of societal infrastructure, and it is expected there will be demand for wireless communication at high-speed and capacity, which will eliminate user awareness of the connection, and also for wireless communication in unexplored areas, which will enable observation and measurement of things that are not visible now. This laboratory is exploring applications of 5G Evolution & Beyond (5G E&B), including R&D on (1) Terabit-class wireless transmission and (2) under-sea acoustic communication.

Low Power Wide Area (LPWA) featuring wide-area, low-speed communications is a promising technology for IoT-oriented radio access. To enable its use in control applications, we are working on radio-signal-reachability enhancement technology to improve the reliability of LPWA connectivity and eliminate the out-of-range state for IoT terminals that, unlike people, are immobile. Furthermore, to use high-definition video in IoT applications in conjunction with increasingly sophisticated image analysis technology, we are developing millimeter-wave propagation control technology for instantaneously transmitting large volumes of data.

With the launch of the fifth-generation mobile communications system (5G) scheduled for 2020, the communication network from that point on is expected to become a "social infrastructure supporting everyday life and industry by connecting people and all sorts of things by wireless means. New technological developments are expected in the radio access system to support such a network including greater capacity of course and enhanced reliability as well. Making use of the hubs of cellular and Wi-Fi operators as well as new hubs and existing forms of radio access, we are researching and developing wireless network technologies to realize end-to-end service provision from devices corresponding to customer needs to cloud servers via wireless/wired networks.

We are conducting R&D on Orbital Angular Momentum multiplexed transmission technology, which is one method for dramatically increasing wireless communication transmission speeds. OAM is a physical quantity that represents a property of radio waves, with the characteristic that radio waves with different OAM can be superimposed and later separated again. Research on the angular momentum of radio waves has been on-going since the beginning of the 20th century, but with advances in wireless communications technology, use of high frequency bands such as millimeter waves has progressed, and it is becoming more feasible to use these characteristics for multiplexed transmission. This laboratory has proposed an OAM-MIIMO multiplexed wireless transmission technology and achieved wireless transmission exceeding 200 Gbit/s in the 28 GHz-band, in laboratory experiments conducted in 2019 (over a distance of 10 m, with frequency utilization exceeding 100 bit/s/Hz). We are now tackling technical issues that must be solved to achieve our ultimate objective of realizing practical Terabit-class wireless transmission.

High-speed wireless communication is difficult under the sea because radio waves cannot be used, but there is increasing need for under-sea wireless transmission of video for tasks such as doing construction with remote controlled under-sea heavy equipment, or performing equipment inspections using unmanned submersible vehicles. This laboratory is using various signal processing technologies developed for terrestrial wireless communication, and working to increase the speed of wireless communication using acoustic waves, which are not affected by murkiness of sea water or sunlight. Our goal is to create Mbps-class high-speed acoustic communication technology capable of transmitting high-definition video.