Pursuing the Essence of Technology Thoroughly. Passion Is Something You Can Only Pour into What You Love

The “father of LTE” receives a new award ecognizing his contributions to wireless communication technology with a global impact

—Congratulations on receiving the 2025 IEEE Jagadish Chandra Bose Medal in Wireless Communications. What was the award ceremony held in Tokyo like?

Thank you. The award ceremony was held as part of a gala dinner attended by distinguished guests, and awards not only to me but also to other IEEE Awards winners were presented. When the awards were being presented, a short video introducing the winners was played in the venue, and on seeing the video for the first time, I was impressed with how well the photos and other materials that I had submitted were collated, and when I mentioned that impression in my speech, as well as the fact that I had just seen the video for the first time, the audience laughed.

The official notification of winning the award from the Institute of Electrical and Electronics Engineers (IEEE) was by email, which I missed. At the end of 2024, my secretary asked me if I had heard anything from the IEEE, so I checked my email and found that the email informing me of the official announcement of the award in the trash folder. Although I had been informed about the award prior to the email through another source, I was once again reminded that I had actually received the award.

In my career thus far, I have received the Commendation for Science and Technology by the Minister of Education, Culture, Sports, Science and Technology (Award for Science and Technology in the Development Category) in 2014, and the Medal with Purple Ribbon in 2018. Although it is always a pleasure to receive such awards, this latest award comes from the IEEE, so I am especially pleased to be recognized globally.

—This commemorative award is given by the IEEE Awards Program, the world’s premier peer-recognition program, to outstanding leaders and visionaries who have made important contributions to the advancement of wireless communication technology that has significantly impacted the world. You are the first recipient of this award. Could you tell us again about the IEEE and this award and why you are the first to receive it?

As a public-interest organization dedicated to advancing technology for humanity, the IEEE is the world’s largest technical professional organization. The IEEE is the trusted voice in a wide range of fields—from aerospace systems, computers, and telecommunications to biomedical engineering, electric power, and consumer electronics—and earns its reputation through its publications, conferences, technology standards, and professional and educational activities.

For over a century, the IEEE Awards Program has been honoring individuals who have contributed to the advancement of science, technology, and engineering in 21 areas of the technical field that the IEEE is interested in. As a newly established award (in 2025), the Jagadish Chandra Bose Medal in Wireless Communications will be awarded to individuals who have made a significant contribution to wireless communication technology. It recognizes outstanding technical contributions in wireless communications, implementation, standardization, or commercialization of new technologies, impact on the profession and/or society, leadership in achieving goals, previous honors, and other achievements such as publications, patents, or other materials. As the first recipient of this award, I have been recognized for my global leadership in research, development, and international standardization of 3rd generation of mobile communication systems (3G) and 4G and for my contributions to adoption of these standards globally.

Focusing on 3G and 4G, the award highlights my technical contributions, such as the development of cell-search algorithms; however, making me most fortunate and proud is the fact that I have been involved in all generations of mobile communications, from 1G to 5G and am currently working on 6G. I mentioned this fact in my acceptance speech, and I truly believe it. I feel that it was extremely fortunate that the award focused on the mobile communication generations that were at the most critical time in terms of standardization: 3G, which aimed to become a globally unified standard, and 4G, which achieved that aim.

For me, standardization has been a part of system development. It is just a tool, but it is an extremely important and powerful one that I have tried to make the most of. I believe the importance of standardization is not just discussing how to incorporate technology into standard specifications; instead, it is ultimately to spread the technology being standardized widely and to make it useful to society. I think this award is in recognition of understanding these beliefs and activities.

Being highly praised for contributions during the most important period of standardization: the 3G and 4G eras

—The award is being given to research and development concerning 3G and 4G. What are the characteristics of each generation of mobile communication system technology?

On joining Nippon Telegraph and Telephone Public Corporation in 1982, which was three years after the launch of the world’s first car-phone service in Japan, I was assigned to a research laboratory. Although the number of subscribers to that service was not particularly large at the time, the development of a high-capacity system was a major theme. The 1G era was the dawn of analog mobile communications with many different standards in different countries. Starting with car phones, it evolved into mobile phone systems as terminals became smaller. In the 2G era, the number of standards decreased due to Europe unifying its standards; however, 2G systems in Japan, the US, and Europe were different. Japan and the US had made some efforts toward harmonization of 2G standards, and although they shared a common 3-channel time-division multiple access (TDMA) architecture, their 2G systems were incompatible. The Japanese 2G system was called personal digital cellular (PDC), in which voice is also digitally multiplexed. It enabled data and facsimile communications at 2400 kbit/s. The release of the “i-mode” mobile Internet service ushered in a period of explosive growth. Globally, the Global System for Mobile Communications (GSM) standard, which originated in Europe, spread across regions and around the world.

The concept of 3G was to develop globally unified radio interfaces, and discussions at the International Telecommunication Union - Radiocommunication Sector (ITU-R) led to the creation of the IMT Vision—Framework and overall objectives of the future development of International Mobile Telecommunications (IMT) for 2020 and beyond (Recommendation ITU-R M.2083), which included the goal of enabling 2-Mbit/s communications. Proposals were made from various countries and regions. In Japan, the wideband code division multiple access (W-CDMA) system promoted by NTT DOCOMO was selected at an early stage, which was ultimately adopted as part of IMT-2000. W-CDMA later evolved into HSPA (high-speed packet access), which enabled packet communication rate exceeding 2 Mbit/s up to 14.4 Mbit/s.

When 3G was officially launched onto the market, NTT DOCOMO was steadily progressing with research on 4G, and around 2002–2003, it achieved a data rate of 100 Mbit/s, and even 1 Gbit/s, at the research level. While research was progressing, however, the number of 3G subscribers was not growing as expected, and in this disappointing situation, it seemed extremely difficult to bring the results of 4G research to the market. The lesson learned from that period is that a smooth evolutionary path between generations is important. Therefore, we proposed the “Super 3G Concept.” This concept was to first develop 3G—as so-called “Super 3G”—then build 4G on top of it. This plan was purely conceptual, and, in fact, our aim was to adopt orthogonal frequency-division multiplexing (OFDM) developed for 4G. Standardization of Super 3G resulted in the Long-Term Evolution (LTE) standard. LTE uses MIMO (multiple input multiple output), a technology that increases communication speed by simultaneously transmitting and receiving data via multiple antennas. Voice over LTE, which digitizes voice signals and transmits them via packet communications, was also adopted, making it possible to adopt new audio codec for clear sound quality.

—Would you share any memorable episodes concerning the difficulties that you faced in the arena of international standardization, where the aims of various countries and regions intersect?

For 3G, the aim was to create a globally unified standard, and fierce debate ensued as players from each country tried to make their technology the international standard. The debate became heated as each country and region selected their technology until, finally, each technology was integrated into the global standard.

At that time, five candidates, one of which was W-CDMA, were being considered for the standard system in Europe. Within the European Telecommunications Standards Institute (ETSI), a fierce debate regarding the choice between W-CDMA and time-division (TD)-CDMA continued for about a year. Japan had already decided to adopt W-CDMA, which was promoted by NTT DOCOMO. Although this discussion took place in Europe, NTT DOCOMO was also deeply involved, and as its staff member, I made business trips to Europe frequently during that time. At one such meeting with a European operator, it was agreed to use W-CDMA for wireless access with GSM as the core network protocol. Finally, at a meeting held in January 1998, it was decided that the European standard would be based on W-CDMA and partly incorporate TD-CDMA. During this process, I had a separate technical debate with an engineer from a vendor who was promoting TD-CDMA, but later, I co-authored an article with that engineer, and the article was published in the IEEE Communications Magazine.

In the United States, major players were promoting a different standard from W-CDMA, namely, CDMA2000. Although it may be seen as a battle between Japan and Europe versus the United States, strictly speaking it was not a battle between countries and regions but a debate between promoters of W-CDMA and CDMA2000 and a discussion between individual vendors and operators. This period was the final stage in our quest for a globally unified standard. It was not just a technical debate; it was also a debate over how to handle intellectual property rights (IPR) such as patents, which are, in a sense, inextricably linked to standardization. This situation put the progress of standardization in jeopardy to the point that, at the time, it seemed as if an international standard for 3G would never be established. Numerous attempts were made to technically harmonize W-CDMA and CDMA2000, but they were met with successive failures. In the end, the harmonization proposal discussed by the Operator Harmonization Group (OHG) was agreed upon. Although some parameters were changed to increase commonality, the proposal was to recognize both methods and define extensions for interoperability; in other words, it was not a truly globally unified standard. The IPR issue was also resolved by agreement between vendors, and standardization was to proceed in accordance with the OHG harmonization proposal. NTT DOCOMO was proceeding with system development in preparation for the commercial launch of 3G in 2001; however, changes to key parameters at the final stage and delays in standardization had a major impact on commercial-system development, which was a challenge.

In regard to 4G, the lesson learned from 3G—ensuring a smooth evolutionary path to the next generation—was important. I mentioned earlier that NTT DOCOMO’s 3G business was not growing as expected, in fact, other operators, including those in Europe, were hesitant to invest in the next generation after making huge investments in 3G, and they were reluctant to standardize 4G. Therefore, standardization of 4G began with the creation of a group of people who wanted to start the standardization. We started with individual meetings with vendors with a strong influence on standardization, and we gradually increased the momentum for standardization through multilateral meetings including operators. These vendors included those who had been our opponents in the CDMA2000 debate, and we recognized that many of them were technically advanced and had respectable engineers. We moved forward in a cooperative relationship, just as in the phrase “yesterday’s enemy is today’s friend.”

I remember that an agreement was reached to begin discussions at a meeting of the 3rd Generation Partnership Project (3GPP) in December 2004, and the content of an interview I gave with reporters there were reported on the front page of the Nikkei newspaper’s morning edition on New Year’s Eve as “Super Third Generation.” As discussions at 3GPP progressed, the abbreviation for the work item, “LTE,” which stood for “Long-Term Evolution,” became well known.

Standardization of CDMA2000 as its evolved form, ultra mobile broadband (UMB), was also moving ahead. Since CDMA2000 was easy to upgrade from cdmaOne, which was considered the second generation, it quickly took off; however, W-CDMA was based on the GSM core network, and operators who used GSM, which had become widely used for 2G worldwide, naturally adopted it, so it became clear that the number of W-CDMA subscribers would surpass that of CDMA2000 many years after standardization of W-CDMA. In this situation, the major CDMA2000 operators announced that they would introduce LTE instead of its evolved form, UMB, and it became clear that LTE would become the only globally unified standard. I later had the opportunity to meet the chief technical officer of the CDMA2000 operator who is said to have made this decision and expressed my gratitude. Standards are not always decided in standardization forums; that is, they can be determined by the market. Ten years later, the importance of reading market trends and the correctness of the decision to ride on the success of GSM have been proven.

Promoting standardization to disseminate technology standards while making technology more affordable and spreading it further to create a world in which people can benefit from it

—Looking at standardization and research and development as a former developer of each generation of mobile communication systems and as your current position as director of the ITU’s Telecommunication Standardization Bureau, what are your thoughts on the future development of Beyond 5G/6G technologies?

As exemplified by discovering the “law of great success for even-numbered generations of mobile communications only,” I enjoy predicting future trends through analysis. I am always conscious of and analyze the trends in technology and development through wondering why they occur as they do. My intention is to grab people’s attention with an unexpected message while conveying an important message.

When I looked at the technological developments in mobile communications from that perspective, I realized that this law of even-numbered generations’ success would no longer hold in the future. I realized this when a reporter from the economics department asked me a simple question in a recent interview: “Why do mobile communication systems undergo a generational change?” Until now, a new generation has appeared about every 10 years. If that has happened three or four times, it is natural to think it will continue to be the case that a new generation will appear every 10 years.

Up until 4G, new wireless access technologies emerged with each generation change, from analog FM (frequency modulation) to digital TDMA, W-CDMA, and OFDMA. However, from 5G onwards, technologies can be said to be an extension of current technologies rather than ones based on new concepts. I called this way of extending current technologies, such as increasing the number of antennas, “brute-force technology.” In terms of technological evolution, the situation is thus changing from 5G onwards. Furthermore, from the perspective of standardization, the situations up to 4G, which led to a globally unified standard, and the situation concerning 5G are different. In light of these changes, I have recently come to think that the application of the previous “law of mobile communication generations” to 5G and beyond may be in jeopardy.

In the case of 5G, while there is the positive side of attracting attention from other industries, which leads to collaboration between industries, I think there is also the negative side of 5G being used excessively as a marketing tool, causing confusion in the market.

It is important to identify the true nature of technology without being distracted by marketing and branding and consider carefully when and which technologies should be popularized in the next decade and the next generation. From my current position at the ITU, I must also pay attention to the fact that one-third of the world’s population is still not connected to the Internet, and many countries still rely on 2G. A generational change that is faster than necessary risks widening the gap with these regions. It is necessary to pursue generational evolution that optimizes the ecosystem of the entire world for developing countries as well as technologically advanced countries.

—Finally, what are your future aspirations? And what is your message to the next generation of researchers and engineers, both inside and outside NTT?

When I first joined NTT, I conducted research and development out of curiosity, but in the end, the results of that research and development were not adopted, and I think now that the laboratory made the right decision that they were not truly useful. Even with those experiences, I have always worked on my job with a passion for technology. At the time, I was absorbed in research and development, and I never would have imagined receiving this award or being in the position I am in today. I was always striving to advance technology and improve performance. Generally speaking, technological advances lead to happiness in people’s lives and society, but technology for the sake of excessive marketing, or advances that are not rooted in the essence of technology, have a negative impact on the world as a whole. Looking back from my current position, I need to examine whether my past attitudes and achievements had a positive effect on the global ecosystem, but I believe that technological advances have contributed to making society better.

Regarding my message to researchers and engineers, it is best for you to focus on developing technologies that interest and inspire you; however, it is important to remember that your work should be useful to people worldwide. Many different people populate the world, and they live with different cultural and economic backgrounds. Being useful to all those people means that technologies must be usable anywhere in the world; international standards make that possible. Therefore, I urge you to proceed with technological development with an awareness of the value of international standardization, and to progress in that manner, I also urge you to cherish your passion.

The current position of director of the ITU’s Telecommunication Standardization Bureau is elected, and I am currently working hard to meet the commitment I made on being elected to spread technical standards worldwide. I believe that international standardization has value only when standards are not only developed but also widely adopted. I will continue to work diligently on international standardization to promote the spread of technology standards, thereby making services more affordable, spreading technology further, and working to create a world in which people and society can benefit.