Softbank, Kanazawa Institute of Technology and Kyoto University have announced the world's first successful demonstration of a system that combines millimetre-wave communication and wireless charging, with the aim of practical application around the 2030s.
■ Millimetre wave charging.
The initiative is to combine communication and power charging in preparation for the Beyond 5G/6G era. Wireless power transmission (WPT) itself is already being researched by other companies, but mostly in the Sub6 band. The three parties are aiming to achieve this in the millimetre-wave band, which is used relatively infrequently, in order to minimise interference with other communications.
WPT has had problems from the perspective of widespread use, but the aim is to create a form of extended communication functionality, which is expected to lead to wide-area social implementation and the creation of new industries using the base station infrastructure. The WPT is expected to be implemented in society over a wide area and to create a new industry using base station infrastructure.
It complies with radio wave protection guidelines and has a low impact on humans. The system also incorporates a function to detect the human body, and it is expected to be able to supply higher power in the future by switching off WPT and not aiming the beam.
Charging at base stations
In the demonstration, a system that implements wireless power transmission functions in millimetre-wave communication equipment has been developed. The same antenna is used for communication and power transmission, and by utilising beamforming, millimetre-wave communication and power transmission can be used separately for each time and space.
While generating special OFDM modulation signals that do not reduce the efficiency of WPT, 64QAM is used as the downlink signal to support high-speed, high-capacity communications. This enables high-speed communication and power transmission at the same time.
Antennas with a wide aperture area and high-frequency radio waves improve propagation efficiency, but antennas with large apertures have the problem that their efficiency in the near field is significantly reduced. Therefore, when power transmission using 'focused beamforming', which improves efficiency in the near field and is proposed by Kyoto University, was tested, it was also confirmed that high efficiency was maintained even in the near field.
When power was transmitted to a power-receiving rectenna developed by the Kanazawa Institute of Technology, it was confirmed that each element received 100 µW (microwatts) of power at a distance of 5 m. According to Naoki Hasegawa, acting manager of the Wireless Power Transmission Research and Development Section, Fundamental Technology Research Office, SOFTBANK, if 100 elements were lined up, theoretically 10 mW of power could be expected, which would be sufficient to drive lost and found tags such as Tile and AirTag.
Practical application expected around 2030.
As momentum for the convergence of real and virtual spaces and the use of IoT, such as Society 5.0, grows, the need to address the problem of powering sensing and IoT devices, which is expected to increase in order to realise this trend, has come to the fore.
Some estimates suggest that by 2035 there will be 1 trillion IoT devices worldwide, with each person using 100 devices, making it difficult to charge and use devices at home, as is currently the case.
Wireless power transmission has already been institutionalised in Japan, and Panasonic, Kyoto University and others are preparing a system that can be used indoors within a range of a few metres.
The millimetre-wave-based system is targeted for practical use around 2030, when Beyond 5G/6G is expected to be deployed, and is expected to be used within a range of 10 metres or less from a base station. Business use is envisaged as the initial deployment, and as an image for consumers, for whom subsequent developments are expected, the possibility was introduced of being able to charge lost-and-found tags embedded in credit cards and the like without being aware of it.
Photo:
https://news.yahoo.co.jp/articles/13b15d03f69d1da2d51dae89ed47a37fc20edcef
