Japan’s largest mobile operators are exploring a shared route for millimeter-wave expansion.
KDDI, NTT Docomo, SoftBank, and Rakuten Mobile signed a memorandum of understanding. The agreement covers a joint study of 5G mmWave infrastructure and coverage models.
The move reflects a clear industry concern. mmWave can deliver very high speeds and strong capacity. Yet it struggles with distance, walls, and physical obstacles. Operators need many sites to create reliable coverage.
That requirement changes the investment case. Dense infrastructure costs more to deploy and operate. It also creates headaches around permits, locations, power, and backhaul.
Remy Pascal, an analyst at Omdia, highlighted this challenge. “Because mmWave requires a dense network grid to overcome short range and blockage, the economics are challenging for a single operator,” he said.
The Japanese carriers have not announced a full network-sharing plan. Instead, they will examine technical options and operating frameworks. These could include base stations, repeaters, and related facilities.
Even so, the study could help shape Japan’s next deployment phase. Shared infrastructure may reduce repeated buildouts in the same areas. It may also simplify talks with cities, landlords, and venue owners.
Pascal sees value in that approach. “Network sharing would enable to share the burden and spread costs across multiple parties, strengthening the investment case,” he said.
However, deeper sharing raises practical questions. Operators still compete on coverage, performance, and customer experience. They must also manage security, service control, and regulatory expectations.
For that reason, the first steps may focus on physical assets. Carriers could share sites, poles, cabinets, or indoor locations. This would not require full active network sharing.
Pascal also noted this middle path. “For instance, further physical site sharing arrangements, even without active network equipment sharing, could be beneficial by reducing costs and facilitating site acquisition,” he said.
Japan’s operators also want to use existing mmWave assets more efficiently. The study will evaluate how current facilities can support broader coverage. Each operator will continue its own deployment plans during the process.
The wider market will watch the results closely. mmWave remains attractive for stadiums, stations, business districts, and dense urban zones. It can support high-demand services where mid-band spectrum reaches its limits.
Still, adoption faces familiar barriers. Devices must support the spectrum. Indoor coverage needs careful planning. Backhaul must handle heavy traffic loads.
Pascal summed up the broader view clearly. “Therefore, any agreements, policies, or initiatives that contribute to address these challenges should be seen positively,” Pascal said.
For now, Japan’s study signals caution rather than a revolution. Yet it may offer a practical model. If cooperation lowers deployment friction, mmWave could gain fresh momentum.
