Why Rakuten Mobile’s network keeps getting better: Vice CTO Takeshita explains

By Hiroshi Takeshita, Vice CTO of Rakuten Mobile

When Rakuten Mobile launched its mobile phone carrier services in April 2020, we knew we were entering a market renowned for its exceptional standards. Service providers in Japan offer impeccable coverage and lightning-fast connection speeds, setting a formidable benchmark for any new entrant. Despite these challenges, we embarked on a journey to democratize the mobile industry.

Fast forward to 2024, and Rakuten Mobile has made remarkable gains in network quality and customer base. Subscriber numbers recently surpassed 8 million, and insights from Opensignal, a global analytics company, showed that Rakuten’s Consistent Quality score improved substantially from 2023.

At a recent information session with the press, I provided an in-depth look at the key factors driving these improvements. From AI automation to expanding 5G coverage, I explained why Japan’s newest and most modern mobile network keeps getting better.

Core features of Rakuten Mobile’s Open RAN network

Rakuten Mobile’s network leverages three core strengths: cloud-native virtualization, Open RAN, and AI and network automation.

Whereas traditional mobile networks are dependent on specialized hardware integrated with software, a fully virtualized mobile network separates the two, allowing software to run the network using general-purpose servers. We are operating software that can run radio access network functions on any hardware.

What makes Rakuten Mobile stand out is that virtualization extends through the entire network.
There basically isn’t a single base station in our network that isn’t virtualized. This simplifies equipment configuration at base stations, significantly reducing costs and enabling quicker deployment and upgrades to the network.

The second pillar is Open RAN. Open RAN is an approach to building a mobile network where equipment specifications are open and standardized, allowing multiple vendors to enter the market. By fostering innovation and flexibility, Open RAN enables us to integrate the best technologies from various suppliers and improve overall network performance.

Over the past six years, Rakuten Mobile has deployed over 340,000 open RAN-compatible products, including macro base stations, microcells, outdoor small cells and solutions for skyscrapers. Such a large-scale deployment of various types of radio equipment using Open RAN is rare even globally.

The final pillar is AI and network automation. At Rakuten Mobile, we automate deployment and security settings throughout the network to reduce construction time and costs, enabling remote configuration without the need for on-site visits.

Moreover, by leveraging AI, the network team can detect issues well before they impact the network. Mobile networks tend to show signs before a failure occurs. By learning these signs through machine learning, AI helps us address these issues before they become critical problems.

Customer experience at the forefront

Despite being Japan’s newest mobile network, Rakuten Mobile has made significant strides in expanding and improving its network, which is demonstrated in recent reports from Opensignal.

Our top priority has been providing a stable experience for customers across the country, especially for users who consume a lot of data, such as those who play games or stream videos.

Rakuten Mobile users will be pleased to hear that key metrics for evaluating Rakuten Mobile’s network performance, including video and download speeds have markedly improved from 2023 to 2024, thanks to a series of initiatives we have undertaken.

Enhancing connectivity with platinum band

We have streamlined our focus on five key frequency bands, including the 1.7 GHz and 700 MHz bands. This strategy is tailored to both major and regional cities, ensuring optimal coverage and performance. In a major milestone for the company, commercial services using the 700 MHz band, or “platinum band”, were launched on June 27, 2024. This frequency range boasts excellent signal reach, ensuring superior connectivity.

We plan to establish 10,661 base stations over ten years to expand coverage using the platinum band nationwide. Noticeably, we launched operations in June, ahead of schedule, thanks to the team’s efforts to accelerate the deployment of our base stations.

Another key focus area has been improving connectivity in subways, deep inside buildings, alleys and crowded places. To tackle these areas, we are expanding the bandwidth of shared base stations with the aim of further enhancing connectivity in the Tokyo metro in 2025. By March next year, we expect to see an improvement in connectivity by about 40% in these areas.

5G breakthroughs

To meet the growing demands for faster and more reliable mobile networks, we have made substantial efforts to expand 5G coverage for customers.

In June 2024, we pledged to expand 5G coverage in the Kanto region by 60% by year-end. I’m thrilled to announce, that we’ve not only met this goal but exceeded it, achieving a 110% increase in 5G network coverage compared to January 2024.

Additionally, the deployment of approximately 17,000 5G stations and the incorporation of technologies like Massive MIMO have greatly improved our signal strength and coverage across the country. Compared to traditional antenna types like 4×4 or 8×8, MIMO technology greatly boosts both the distance and strength of the signal from a single base station.

This results in wider coverage and faster communication speeds, offering substantial technical benefits and advantages for our users.

Strengthening disaster response capabilities

Finally, I would like to turn to Rakuten Mobile’s commitment to bolstering network resilience during disasters. As part of our disaster preparedness measures, we have implemented strategies to extend the life of backup power supplies. Our 1.7 GHz base stations are designed with battery capacities and configurations that allow them to operate for about three additional hours during power outages.

This approach helps conserve energy and ensures continued operation during emergencies.

We are also leveraging satellite technology to strengthen our disaster response. In situations where traditional transmission paths are disrupted and cannot be quickly restored, using satellites to link base stations with data centers becomes essential. Our goal is to utilize satellites to connect base stations to our exchange equipment in these critical situations.

Future plans for nationwide coverage

Looking ahead, Rakuten Mobile remains committed to providing best-in-class mobile services to all customers in Japan, regardless of their location. By 2026, we aim to provide satellite-to-mobile services that cover the entire country with AST SpaceMobile. This groundbreaking initiative will enable connectivity in remote areas such as mountainous regions and islands where terrestrial networks are currently unavailable and enhance our disaster response capabilities.

With AST SpaceMobile, we envision area coverage across the whole of Japan, including remote islands, ensuring that every customer, no matter where they are, can stay connected.

Rakuten Mobile’s short journey from newcomer to leading player in Japan’s telecom industry is a testament to our innovation, relentless focus on customer experience and the dedication of our talented team members.

With further advancements in AI, 5G and satellite technology on the horizon, we are poised to deliver even greater network quality and reliability. The best is yet to come.