NTT Docomo : DOCOMO to Commence Deployment of World's First 4G/5G Multi-vendor Radio Access Network Conforming to O-RAN Specifications

September 18, 2019

TOKYO, JAPAN, September 18, 2019 --- NTT DOCOMO, INC. announced today that in collaboration with Fujitsu Limited, NEC Corporation and Nokia, it has successfully achieved multi-vendor interoperability across a variety of 4G and 5G base station equipment compatible with the international standards of the Open Radio Access Network (O-RAN) Alliance, an industry group working to create more open and intelligent next generation radio access networks, including 5G networks. The O-RAN standards include fronthaul specifications and X2 profile specifications. This is believed to be the world's first realization of this level of multi-vendor interoperability in 4G and 5G base station equipment conforming to O-RAN specifications; DOCOMO will deploy the equipment in the pre-commercial 5G service it plans to launch on September 20, 2019 in Japan.

Signal transmission and reception specifications between base station equipment have not been fully internationally standardized until now, and have not been fully consistent among vendors. To ensure the quality of mobile communications, network operators have therefore typically utilized base station equipment from the same vendor, and the choice of equipment has therefore tended to be limited.

The ability to deploy and interconnect base station equipment from different vendors will make it possible to select the equipment most suitable for deployment in any given environment, such as base stations offering broad coverage in rural areas or small base stations that can be deployed in urban areas where space is limited. This will in turn allow more rapid and flexible expansion of 5G coverage.

Concurrent with the pre-commercial launch of its 5G services, DOCOMO will expand 5G coverage by combining 5G networks with existing 4G networks using equipment from diverse vendors. The international standardization of signal transmission specifications that will enable this follows lengthy discussions within the O-RAN Alliance, which DOCOMO is chairing.

Going forward, DOCOMO will continue to refine and develop its cutting-edge base station communication technology, aiming to expand the provision of stable 5G coverage.

In the 4G and 5G base station equipment being deployed in DOCOMO's pre-commercial 5G service, O-RAN fronthaul specifications are used to establish the connections between centralized units hosting baseband processing and remote units hosting radio processing in 5G remote-installed base stations. O-RAN X2 profile specifications are used to establish the connection between 4G base stations and 5G base station centralized units.

O-RAN fronthaul interface specifications provide a foundation for interoperability between centralized units and remote units of 5G remote-installed base stations manufactured by diverse partners. With remote-installed base stations, centralization of the baseband processing will bring the following benefits:

• Improved communication quality through coordination of multiple remote units
• Pooling of resources through the aggregation of hardware
• Minimization of equipment footprint, leading to a reduction in space and costs.

In addition, through the provision of only radio processing, the remote unit can be further downsized, making it possible to install in a variety of locations that would previously have not been viable, such as small buildings or mountainous areas.

The O-RAN X2 profile specifications provide a foundation for interoperability between 4G base stations and 5G base stations manufactured by diverse partners in 5G non-standalone (5G NSA) networks by taking 3GPP*1X2 interface specifications and specifying detailed standards for their usage. 5G NSA networks connect devices using both 4G and 5G technologies. The connection of 4G and 5G base stations makes it possible to combine the high-speed, low-latency data communications delivered by 5G technology with the comprehensive coverage of 4G networks.

1. Third Generation Partnership Project, a standards organization which develops protocols for successive generations of mobile telephony.