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8 October 2019

KDDI takes conventional approach in land of new 5G architectures

Japan has not been in the first wave of commercial 5G nations, by contrast with previous network generations, but its operators are pursuing innovative approaches to their build-outs, and driving the shift towards open, multivendor and cloud-based networks. Rakuten, the new entrant, is famously deploying a cloud-native RAN and core for 4G and 5G, while NTT Docomo recently switched on its first RAN (pre-commercial as yet) based on Open RAN interfaces.

Softbank – always a pioneer of small cells and other creative approaches to 4G roll-out and economics – is now far more than an operator, as its parent group increasingly invests, through the Vision Fund, in many of the technologies, such as AI and quantum computing, which may drive the 5G platform to new heights in the future.

However, the country’s second largest MNO, KDDI, seems to be taking a more conventional approach. As Docomo talks about testing 5G on Japan’s superfast Shinkansen trains, KDDI is working with Ericsson and Nokia (both of which are claiming to be the leading suppliers for the deployment).

Japan’s four operators plan to invest a combined $14.4bn in their network upgrades over the next five years, according to a report in the Nikkei news service. NTT Docomo will spend about $7.1bn, the report said, with KDDI planning $4.16bn, SoftBank $1.84bn, and Rakuten $1.73bn.

KDDI says it will launch commercial 5G by March 2020, using a combination of the Ericsson Radio System (ERS) and Nokia AirScale. It aims to achieve 93% population coverage by the end of March 2025, at a cost of about $4bn in capex.

With Ericsson, it is building on trials in the 4.5 GHz and 28 GHz bands, and will use ERS in both sub-6 GHz and millimeter wave bands. Nokia, already a major KDDI supplier, is engaged in modernization projects, which include installing combined 4G/5G, software-upgradeable base stations to replace older LTE kit.

Like the US operators, KDDI has also introduced Samsung as a third 5G vendor, having – along with the other Japanese MNOs – excluded Huawei and ZTE from its contracts. The Korea Times reported that Samsung had won a five-year contract worth about $2bn but provided few details. To date, the Korean supplier’s strengths in 5G deals have often focused on its expertise in mmWave systems. In January, Samsung and KDDI conducted a 5G test transmitting 4K video on a railway platform in Tokyo using 28 GHz spectrum.

Also on the railways, Docomo said last week that it had succeeded in achieving a stable 5G 8K video transmission between base stations and a high speed train travelling at 283 kilometers an hour. The trial was conducted with the Central Japan Railway Company in millimeter wave spectrum, on the busy train route connecting the cities of Tokyo, Nagoya and Osaka.

The tests achieved data transmission speeds above 1Gbps with “perfect consecutive handover between 5G base stations temporarily sited alongside the track”, as the operator put it.