Connectivity Technology Blog

We have looked at transparent antennas for a while now with my first post on the topic back in 2019. Since then this technology has matured immensely as I detailed in a blog post last year. Transparent antennas are no longer just experimental concepts but have reached the stage of commercial deployment, often combined with infrastructure sharing models to maximise efficiency and coverage. In Japan, infrastructure sharing has taken on special significance. The high cost of network deployment, limited availability of installation sites and the density of urban environments make it challenging for operators to expand coverage on their own. Shared infrastructure helps reduce duplication, control costs and speed up the roll-out of services. For readers unfamiliar with JTOWER , it is a Japanese company specialising in shared telecommunications infrastructure. JTOWER develops and manages towers and in-building solutions across Japan, with the goal of improving connectivity while reducing the...

At MWC 2025, NTT Docomo highlighted its latest initiatives under the NTT Group's "NTT C89" space-business strategy, such as mobile-connectivity services using unmanned vehicles, or high-altitude platform stations (HAPS), that fly in the stratosphere for days or months, using relays to provide mobile connectivity in mountainous and remote areas, including at sea and in the sky. A presentation on NTT C89 Aerospace Business Strategy is available here while a presentation on NTT DOCOMO's Non-Terrestrial Network (NTN) for Extreme Coverage Extension is available here . Stratospheric connectivity, enabled by High Altitude Platform Stations (HAPS), is emerging as a key solution for extending mobile coverage to remote and underserved areas. However, ensuring that these airborne platforms can provide stable, high-quality connectivity requires extensive testing and refinement. At MWC 2025, NTT Docomo showcased its progress in this domain, highlighting multiple real-world trials...

On April 1, 2024, two of Japan's leading connectivity organizations—the 5G Mobile Promotion Forum (5GMF) and the Beyond 5G Promotion Consortium (B5GPC)—joined forces to create the XG Mobile Promotion Forum ( XGMF ). This merger symbolizes a pivotal step in accelerating the adoption of next-generation wireless technologies. In May 2024, XGMF's Millimeter Wave Promotion Ad Hoc (Millimeter Wave AH) hosted the International Workshop on Millimeter Wave Dissemination for 5G. This event aimed to foster the adoption of millimeter wave (mmWave) technology in Japan and beyond, drawing an audience of approximately 200 attendees and broadcasting in both English and Japanese. The workshop featured opening remarks by Mr. Naohiko Ogiwara, Director of the Radio Department, Telecommunications Infrastructure Bureau, Ministry of Internal Affairs and Communications (MIC). Key speakers included: Mr. Takanori Mashiko (MIC, slides ) Mr. Sam Gielges (Qualcomm, online - no slides) Mr. Christopher Pric...

KDDI is a big fan of SpaceX's Starlink satellites. Earlier this year I talked about how it's working to solve rural connectivity issue in Japan with the help of Starlink. In August this year, KDDI signed an agreement with SpaceX to bring Satellite-to-Cellular (Direct-to-Device) service to Japan.  Along with solving the connectivity challenges, KDDI is also looking at Starlink to solve the backhaul challenge in case if disaster strikes that destroys the ground infrastructure. A press release in July detailed this as follows: KDDI and KDDI Engineering will deploy vehicle-mounted base stations and portable base stations that use the satellite broadband service "Starlink" as a backhaul line starting in July 2023, and will deploy approximately 200 base stations, including ship-type base stations, by the end of fiscal 2023. The machines will be introduced nationwide. Through this, we aim to provide customers with high-speed, low-latency au communications even in the even...

National Institute of Information and Communications Technology ( NICT ) is Japan’s sole National Research and Development Agency specializing in the field of information and communications technology. It is charged with promoting ICT sector as well as research and development in ICT, which drives economic growth and creates an affluent, safe and secure society. Free-space optical communications have the potential to bring the bandwidth of optical fibers to moving platforms, greatly enhancing their communication capabilities. This communication technology has already become mature after numerous demonstrations during the last few years. Free-space laser communication is expected to play a key role to cope with the demanding bandwidth requirements of 5G (and beyond) networks to support an increasing number of wireless terminals disseminated throughout the world and generating an unprecedented amount of data. For this purpose, practical and versatile lasercom systems will be necessary to...

Recently I blogged about Disaster Roaming in 3GPP Release-17. While this will take time to be implemented worldwide, it is already available in Japan, maybe not in the 3GPP standardised way. Similarly, back in 2011, I blogged about Earthquake and Tsunami Warning service (ETWS) from NTT Docomo's Journal, it was two days before the  2011 Tōhoku earthquake and tsunami hit. Japan is no stranger to earthquakes, typhoons, and other natural disasters, which can have a devastating effect on infrastructure. To ensure that the mobile networks keep functioning, operators work extremely hard to ensure people remain connected one way or another. NTT Docomo has released a video detailing the countermeasures to keep everyone connected in case of emergencies. The following detail is provided with the video: DOCOMO's network is no exception, and our services could get cut off by a base station power outage, disconnected fiber-optic cable, or other malfunctions. DOCOMO established the three p...

In Nov 2022, Rakuten Mobile announced that it has obtained preliminary experimental test station licenses to conduct mobile communication tests and preliminary verification in Japan using AST SpaceMobile’s low earth orbit satellite, BlueWalker 3. We blogged about AST & Science's ambition to have SpaceMobile beam 4G/5G directly to devices here and here . Back in Nov. AST SpaceMobile announced that it had successfully completed deployment of the communications array for its test satellite, BlueWalker 3 (“BW3”), in orbit. I found the Tweet showing the unfolding very interesting. History is unfolding! We've deployed #BlueWalker3 's 693-square-foot array, which is now the largest-ever commercial communications array in low Earth orbit. Read more about this important milestone here: https://t.co/4kupfxn3vO pic.twitter.com/KnE9CeWOCT — AST SpaceMobile (@AST_SpaceMobile) November 14, 2022 Coming back to Rakuten Mobile's announcement, the press release said: In order to...

NTT Docomo and Airbus have demonstrated the ability to use Airbus's solar-powered Zephyr High Altitude Platform Station (HAPS) to deliver future wireless broadband connectivity. The trial took place in the United States in August, when the Zephyr S aircraft undertook approx. 18-day stratospheric flights to test various capabilities. We have covered many of the topics here, see related blog posts link at the bottom. A press release said: Carrying an onboard radio transmitter, the Zephyr S provided an agile datalink during a stratospheric flight to simulate future direct-to-device connectivity. Test data was captured at different altitudes and at different times of day and night, focusing on assessing how connectivity is affected in the stratosphere by factors including weather conditions, different elevation angles and aircraft flight patterns. Tests included various bandwidths to simulate direct-to-device service from the HAPS to end users using low, nominal and high throughput. T...

NTT Technical Review Vol. 19, No. 2, Feb. 2021 provided a fantastic summary of Standardization of Next-generation Wireless LANs in the IEEE 802.11 Working Group. Here is an extract from the article : Institute of Electrical and Electronics Engineers (IEEE) 802.11 is a working group (WG) within the IEEE 802 LAN/MAN Standards Committee that helps develop standards related to local area networks (LANs) and metropolitan area networks (MANs). It is responsible for standardization of physical layer and medium access control (MAC) layer technologies of wireless LANs. There are several types of subgroups within the IEEE 802.11 WG. A task group (TG) is a subgroup responsible for developing a technical standard or recommended practice. A study group is a preparatory group to create a TG to discuss use cases, technologies, and feasibilities. As a result of discussion, a study group creates documents called Project Authorization Request and Criteria for Standards Development. There are also a grou...

Rakuten and Vodafone have become the lead investors in a venture to extend mobile coverage to more people and devices across the planet, using the first mobile broadband network that will be broadcast from space. The venture also has other investors includeing American Tower; Cisneros; Samsung NEXT; and founder Abel Avellan. A Japanese news site reported that Rakuten will be the biggest investor. Rakuten has already said that they want to provide 100% geographic (not population based, which is easier) coverage in Japan. This point was emphasized by Rakuten Mobile's CTO Tareq Amin in a recently released video. Vodafone's press release also mentioned some of the reasons they have invested in AST: Branded SpaceMobile, the low-Earth-orbit (LEO), low-latency satellite network from AST & Science will be the first in the world to connect directly to standard smartphones. The company holds an extensive patent and IP portfolio for its ground and space technologies. A...