Friday, 22 January 2021

NTT Docomo's 5G Network is based on 'Open RAN' Principles

I have detailed many different details from NTT Docomo over the years as they are not just one of the few innovative operators but are also very happy to share lots of interesting details. Their RAN Infrastructure post was posted in November but already reached top 5 posts on this blog. 

In a recent interview with Telecom TV, Sadayuki Abeta, Vice President & General Manager of the Radio Access Network Development Department at NTT DOCOMO, talked about the Japanese operator’s experience with Open RAN deployments, starting with its multi-vendor 4G network and now with its 5G rollouts. His talk, embedded below, points out that even though they have not yet adopted vRAN, they consider their network to be Open RAN based on the open Interface principles. 

Back in September, Docomo had couple of announcements about the 5G Base Stations based on O-RAN specifications.

The first announcement was about Docomo and NEC announcing that they have expanded multi-vendor interoperability by interconnecting a new 5G base station baseband unit (5G-CU/DU), developed by NEC and Samsung Electronics and compliant with O-RAN Alliance specifications, with 5G base station remote radio units (5G-RUs) of other vendors on DOCOMO's commercial network.

Expanding multi-vendor interoperability based on O-RAN open interface specifications will enable the most appropriate base stations to be used depending on deployment scenarios and taking advantage of specific vendor and equipment characteristics. This will drive the rapid and flexible development of 5G service areas.

The new 5G base station baseband unit from NEC realizes multi-vendor interoperability and is the result of a partnership between NEC and Samsung. It is interoperable with all existing vendors' 5G base station remote units in DOCOMO's network owing to its adoption of O-RAN open fronthaul specifications; it is also compatible with all existing 4G base stations in DOCOMO's network thanks to its adoption of O-RAN open X2 specifications.

Multi-vendor interoperability using O-RAN open fronthaul specifications was also confirmed for NEC's macro-cell 5G-RU, which provides wide area coverage, and for NEC's fronthaul multiplexer (5G-FHM), which copies and combines the fronthaul signals to and from multiple 5G-RUs to form a single area; both are new 5G base station equipment offerings.

During their collaboration, DOCOMO selected the test items, executed the multi-vendor interoperability tests and analyzed the results; NEC and Samsung Electronics supplied the 5G base station equipment and analyzed the test results.

The second announcement was about DOCOMO, Fujitsu and NEC achieving what they believe to be the world's first carrier aggregation using 5G frequency bands in a multi-vendor radio access network (RAN) based on O-RAN specs.

Carrier aggregation was achieved using the 3.7GHz and 4.5GHz bands designated for 5G networks. In addition to this dual connectivity achieved by bundling LTE bands, downlink speeds of 4.2 Gbps will be achievable, enabling ultra-fast data transmission. DOCOMO already provides commercial 5G services in Japan through a multi-vendor RAN that connects baseband units and remote radio units manufactured by Fujitsu and NEC based on O-RAN's open fronthaul specifications. The same system configuration was used to achieve this 5G carrier aggregation.

Mr. Nozomu Watanabe, Senior Executive, NEC Corporation and Mr. Sadayuki Abeta, VP & GM, Radio Access Network Development Department, NTT DOCOMO explained their Open RAN vision and approach in a Telecom TV interview baback in November which is embedded below.

It's just a matter of time before we see more of these interoperability announcements, not just for 4G & 5G but also for 2G & 3G.

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