Cross-operator joint study on 5G mmWave infrastructure and technical architectures for coverage expansion

Tokyo - KDDI Corporation, NTT DOCOMO, INC., SoftBank Corp., and Rakuten Mobile, Inc. announced today that they signed a memorandum of understanding (MoU) on September 11, 2026, to launch a joint study on utilizing 5G millimeter-wave^*1 infrastructure and technical architectures to expand coverage.

While millimeter-wave spectrum enables ultra-high-speed, high-capacity data transmission, its propagation characteristics make signals susceptible to attenuation and obstruction by physical obstacles. Consequently, expanding millimeter-wave coverage requires the development of a large number of base stations and related equipment, making rapid coverage expansion an industry-wide challenge for telecommunication operators.

Based on the premise that each operator will continue its own millimeter-wave deployment, this initiative aims to deliver high-quality millimeter-wave experiences to more customers through cross-operator collaboration.

Overview of the Joint Study
Through this study, the companies will assess the technical feasibility of expanding 5G millimeter-wave coverage among mobile network operators and evaluate efficient operational frameworks for its implementation.

To achieve this expansion through collaboration among mobile network operators, this study will focus on technologies and approaches related to 5G millimeter-wave base stations, repeaters, and other related assets. While each operator actively deploys its own 5G millimeter-wave equipment, the companies will pursue concrete studies to effectively utilize deployed facilities.

Going forward, the companies will continue working to expand Japan’s 5G millimeter-wave infrastructure and provide high-quality, seamless connectivity to a wider range of customers, thereby contributing to the advancement of Japan’s digital infrastructure.

Notes
*1 28GHz frequency band