Meta-Structure Reflect-Array Technology Could Solve the 28 GHz 5G Line of Sight Requirement

NTT DOCOMO in collaboration with Metawave Corporation has demonstrated a 5G mobile communication system that operates in the 28 GHz-band using meta-structure reflect-array technology. This successful demonstration took place in in Koto-ku, Tokyo on November 29, 2018. Meta-structures are an artificial medium with optical characteristics developed by arranging structures that are sufficiently small with respect to wavelength in the form of an array. The meta-structure reflector will be exhibited at the DOCOMO Open House 2018.

The communication speed achieved in this demonstration with Metawave’s meta-structures reflect-array in place was 560 Mbps, compared to 60 Mbps with no reflector.

The meta-structures reflector developed by Metawave uses very small structures (compared to the free-space wavelength), that are arranged across the array to have different shapes based on their position within the array. It is possible to arbitrarily design the direction of the reflected wave gain and the shape of the beam (beam-width). As a result of this, the solution can be installed on walls of buildings to directly reflect waves in specific directions. And, the installation location in any given city is not limited, enabling the area to be expanded in high traffic areas.

DOCOMO designed the 5G demonstration trial sites, considering the selection of installation location, beam control direction, etc. In the high-frequency bands used for 5G, it is difficult to expand the coverage area outside the line-of-sight of the base station antenna, and it is expected that the industry will utilize the reflection of radio waves as a solution. A metallic reflector is one technique that has been tested, which reflects radio waves. However, this solution requires the installation of a metal plate based on the direction of the incident angle of radio waves to control the angle of the reflected wave, which is difficult to install in cities, and is therefore limited to specific usage in the suburbs.

In this demonstration, a meta-structure-based reflect-array was installed at the 5G trial site and was tested for covering a 5G area at the foot of a building, where a 5G base station radio was installed and a vehicle equipped with a 5G mobile station was used. As a result, the communication quality was greatly improved in the area where 5G data communication was previously impossible with range extension of about 35 meters. By using the meta-structures reflector, the communication speed improved by 500 Mbps for the vehicle equipped with the 5G mobile station. DOCOMO will continue to research and develop area building technologies using meta-structures in an effort to establish an efficient and flexible area construction method for the 5G area.

The 5G trial site is located at Koto-ku, Tokyo. 5G data communication using 28 GHz band was measured between the 5G base station (Ericsson) located in Tokyo International Exchange Center rooftop and the 5G mobile station (Intel) running experimental vehicle. The meta-structures reflector used in the demonstration, the reflection direction and the beam shape of the reflected wave are determined so that the area of the 5G site is expanded using these tiny structures to form the beam arranged in the plane of the reflect-array. In this demonstration experiment, the reflected wave from the meta-structure reflector is used to extend the 5G area where the Tokyo International Exchange Center becomes an obstacle and is out of sight.