Saturday, 11 July 2020

NTT Docomo Provides an Overview of 5G Commercial Service

There is no shortage on posts about NTT Docomo on this blog and other sister blogs. Not only are they innovators and trend setters, they have pioneered quite a few technologies that have gone mainstream after many years of them trying it out.


While Docomo launched their 5G network only recently, they have been working on it for a very long time, since 2010. They have published an article on this in the latest instalment of their Technical Journal here. The following is just some selective extract:

Prior to launching its 5G commercial service, NTT DOCOMO began basic 5G studies in 2010 and commenced high-frequency-band trials in 2014. Then, after contributing to early formulation of 3GPP standards for 5G in collaboration with major global mobile enterprises, NTT DOCOMO launched its 5G pre-commercial service in September 2019 creating many solutions together with co-creation partners.

Going forward, NTT DOCOMO plans to construct and roll out 5G service areas successively starting with major train stations/airports and stadiums in urban and regional areas as well as various types of facilities with partner collaboration in mind.

High Speed and Large Capacity: The 5G system will provide much higher broad- band data transmission compared with the existing system. It will realize high-definition video including Virtual  Reality  (VR) and  Augmented Reality (AR) experiences while enabling users to enjoy high-presence video and services as a familiar part of life. 

The maximum receive speed will be 3.4 Gbps achieved through the use of various technical advances such as high-order Multiple Input Multiple Output (MIMO) technology and the combining of many frequency bands. This value corresponds to the maximum receive speed at the time of the 5G commercial service launch as shown in Table 1, but NTT DOCOMO will continuously improve transmission speed through a variety of technical approaches including higher spectral efficiency.

Low Latency:  In 5G, low latency will enable high-real-time control. For example, it can contribute to even higher levels of automation by determining current running conditions of plant facilities and machines and controlling and operating them in real time.

Also in 5G, the radio transmission unit has been shortened to one-half to one-eighth that of 4G depending on the frequency band,  and  the  timing  for confirming delivery has been positioned immediately after data transmission. These technologies combined are expected to achieve low latency in the radio interval compared with 4G. In addition, the adoption of Multi-access Edge Computing (MEC) is expected to achieve low latency on an end-to-end basis.

NTT DOCOMO has achieved its 5G service through a non-standalone format in which terminals  connect to  the  mobile network through both the NR and eLTE radio access systems. Specifically, it has leveraged the know-how obtained in deploying an Advanced Centralized Radio Access Network (Advanced C-RAN) in LTE to provide high-speed communications through Dual Connectivity (DC), which uses two radio access systems in an area in which both NR and eLTE (eLTE is defined as an LTE communication specification conforming to 3GPP Rel. 15 or later.) can be used.

A system configuration diagram of the 5G service is shown in Figure 2.


Up to now, specifications for interconnecting base station equipment (signal send/receive rules) differed from vendor to vendor without sufficient consideration given to international standards. This situation made it difficult to interconnect base sta- tion equipment of different vendors so the usual approach was to interconnect base stations from the same vendor. However, in the 5G launch period, in which expansion of the 5G area would take place while using the existing 4G network, this approach would limit the vendors of 5G base station equipment that can be selected to vendors of 4G base station equipment. To solve this problem, the Open Radio Access Network (O-RAN) Alliance that NTT DOCOMO has been participating in promoted the international standardization of interoperability specifications between base stations thereby unifying interoperability specifications across 4G and 5G base station equipment and enabling multi-vendor connections.

These interoperability specifications have made  it possible to deploy newly developed 5G base stations without having to rely on 4G base-station vendors and to achieve a speedy 5G rollout while using existing 4G assets.

You can read the complete article here.

Finally, if you were wondering what NTT Docomo's real world speedtest results are, here is one of them from twitter.



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