KDDI is working with Ericsson on the deployment of 5G base stations in underground vaults. The idea is to save precious space in Japan’s crowded cities to installing 5G base stations in “manhole-shaped” vaults. Power infrastructure would remain below ground with fiber connected to antennas on the ground level. This allows for fast permit process and deployment, while ensuring no visual impact on street environments.
KDDI is the first communications service provider in Japan to begin operating vault 5G base stations.
In Japan, many base stations have been installed on steel towers and building rooftops to achieve high-speed and reliable mobile communication over wide areas. However, there have been challenges, such as restrictions on the installation of base stations in scenic areas due to landscape considerations. In July 2021, the Ministry of Internal Affairs and Communications (MIC) enacted a new system of radio wave protection guidelines for vault base stations, making their construction and operation possible in Japan.
Ericsson has developed sub-terrain antennas that can deliver robust connectivity in a confined space, like manholes, where fiber and power already exists and where the installation of standard sites is not possible. Being installed underground, the antenna provides optimal radiating characteristics (MIMO) upward in built-up environments while being less susceptible to wind load.