Japan’s third largest mobile operator SoftBank has signed separate TD-LTE network development deals with both of China’s major telecoms equipment makers – ZTE and Huawei.

SoftBank said today it has worked out a deal with ZTE to use its “pre-5G” technology based on TDD technology, with pre-commercial test networks to be completed by early next year.

ZTE VP Li Cui said it will set up a wireless R&D centre in Tokyo by the end of the year, but he declined to disclose the size of its investment.

Meanwhile, cross-town rival Huawei announced today it has signed an agreement to cooperate with the Japanese operator on the development of TDD+, a 4.5G technology based on LTE-TDD that Huawei introduced last October.

The company is pushing 4.5G to bridge the gap between 4G and 5G, which likely won’t be ready until at least 2020 and mass deployments aren’t expected until 2022.

ZTE has been talking up its pre-5G concept since November, saying it will be available much sooner than 5G (which hasn’t been officially defined and has a timeframe for commercial launch of beyond 2020).

ZTE told Mobile World Live that with SoftBank it plans to start initial field testing in Q3 using its pre-5G Massive MIMO (multiple input multiple output) offering. Based on ZTE’s data, it said pre-5G networks will have four to six times higher throughput compared with 4G networks.

Meanwhile Huawei said in a statement that the use of TDD+ will enable SoftBank to increase the frequency resource efficiency on its network by about five times.

SoftBank SVP Keiichi Makizono said TDD+ technology will become the next-generation network development trend. “Our cooperation with Huawei on 4.5G technology will be quite meaningful in helping us to construct the next-generation mobile network.”

SoftBank has been a leader in the use of unpaired TDD spectrum. It has more than 10 million TD-LTE subscribers, which represent two-thirds of its 4G customer base. It has deployed 54,000 TD-LTE base stations.

SoftBank’s rival NTT Docomo latest month gave an update on its plans for its targeted 5G launch from 2020, which will be split into two phases – tagged 5G and 5G+. The operator’s initial deployment will centre on enhancements to LTE and the deployment of some new radio access technologies, Takehiro Nakamura, VP and director of RAN for the company, explained: “But I think that in 2020 it will be very difficult to use the higher spectrum bands. So maybe below 6GHz is the main target.”

With the availability of new bands after 2020, what Docomo is referring to as 5G+, “a full package of 5G hopefully can be deployed around 2022/2023”.