Tuesday 14 March 2023

KDDI's Underground 5G Base Stations

Some five years back I talked about NTT Docomo's underground LTE base stations, now it's KDDI's turn for an underground 5G base station. Last week the Japanese operator KDDI announced to the world that they are testing an underground base station in a handhole (just big enough for the hand to go in as opposed to manhole where a person can go in). 

The press release (translated by Google from Japanese) said:

In December 2022, KDDI became the first domestic telecommunications carrier to begin operation of an embedded 5G base station (hereafter referred to as this base station) in Otemachi, Chiyoda-ku, Tokyo (on the premises of the KDDI Otemachi Building).

In the future, we aim to accelerate the expansion of areas that require consideration of scenery, such as Bikan districts, by utilizing this base station


Conventional tower-mounted base stations and building roof-mounted base stations have exposed base station antennas, which can affect the scenery. It was. As one solution to this problem, the introduction of buried base stations, in which the base station equipment is installed underground (below the ground surface), is expected. In July 2021, the Ministry of Internal Affairs and Communications' new system of radio wave protection guidelines for embedded base stations came into effect.

About this base station

Since 2018, KDDI has been considering the start of commercial operation of embedded base stations. In December 2022, we succeeded in emitting radio waves from this base station, and verified radio wave propagation characteristics until February 2023, confirming that a communication area with a radius of about 50m can be secured.

By storing the devices necessary for radio wave radiation, such as wireless devices and antennas, in a housing buried underground (below the ground surface), it is possible to install the device in consideration of the landscape. In addition, by radiating radio waves upward, it will be an area along the ground.

It adopts a highly waterproof metal housing and is designed to withstand water intrusion. Also, since the antenna is underground, it is less susceptible to strong winds.

KDDI will continue to develop new concept base stations that are not bound by existing base station installation forms, and will continue to expand service areas, improve quality, and create an environment that is easier for customers to use.

Nice to see mobile enthusiasts already testing the base station out. We will have to wait to see how the PoC goes and if we will see more of these deployed commercially. 

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