SoftBank Mobile Corp. has raised the stakes in Japan’s wireless broadband race, promising a 110Mbit/s download peak connection speed over a network built using a new standard that appears to be Long Term Evolution Time Division Duplex (LTE TDD) in all but name.

It will be notionally the world's fastest mobile network when Wireless City Planning Inc., a Softbank subsidiary, starts commercial service on Nov. 1, although downlink speeds on the first available device will max out at 76 Mbit/s.

The network, and the AXGP (Advanced eXtended Global Platform) technology underpinning it, are all about repositioning Softbank, Japan's third-largest mobile operator, in the highly competitive mobile broadband market ahead of the loss of its status as Japan's sole iPhone partner.

But while AXGP is a new standard -- officially an evolution of the old PHS -- it's close, if not actually identical, to LTE TDD. (See Vendors Invest in Softbank Wireless Broadband.)

Just how close Softbank hasn’t made completely clear, although chief Masayashi Son told a Sept. 30 press conference that the two are "100 percent compatible."

AXGP has developed in tandem with the TD technologies. Its main backer, the XGP Forum, has formed a technical alliance with the TD industry group in China.

The AXGP baseband and air interface both conform to the 3rd Generation Partnership Project (3GPP) LTE TDD standard, and Huawei Technologies Co. Ltd. 's node B radio access network (RAN) equipment and the Qualcomm Inc. (Nasdaq: QCOM) chipset installed in the initial device both use LTE TDD chips, a source close to the situation said. (See Softbank Unit Uses Huawei's Mobile Gear.)

Softbank's 4G license, acquired when it bought failed PHS operator Willcom in early 2010, also stipulates the use of AXGP, the source said.

Marc Einstein, Tokyo-based industry manager at Frost & Sullivan , says the unique technology also works as a selling point in the market. "Japan loves its own standards, going back to [2G technology] PDC," he notes. "But I’m not convinced it's not LTE TDD under another name."

Softbank’s Son has also taken a high-profile global role in pushing LTE TDD. He joined China Mobile Ltd. (NYSE: CHL) boss Wang Jianzhou and Bharti Airtel Ltd. (Mumbai: BHARTIARTL)'s Sunil Mittal in promoting the technology at the launch of the Global TDD Initiative (GTI) during the Mobile World Congress in Barcelona last February. (See Global TDD Initiative Launched at MWC 2011.)

Softbank plans to invest more than US$1 billion in the new network, the source told Light Reading. It will reach more than 90 percent of major cities by the end of April 2013.

Ericsson AB (Nasdaq: ERIC), Huawei and ZTE Corp. (Shenzhen: 000063; Hong Kong: 0763) are the main suppliers of network gear for the network. ZTE said in a Chinese-language press release that it was Softbank’s “primary strategic partner” in “jointly building a TDD network.” It did not provide details of the kit supplied, although it said the two companies may establish a joint laboratory to develop next-gen wireless technology.

Huawei deployed its Single RAN platform for the initial rollout in Tokyo, and said it would be selling additional equipment to Softbank. The network uses Ericsson's packet core and Alcatel-Lucent (NYSE: ALU) equipment for the backhaul transport connections. (See SoftBank Unit Backhauls With AlcaLu and Ericsson Builds Softbank's Packet Core.)

Demonstrating the first device, dubbed the Ultra WiFi 4G, Softbank's Son said it would be able to link up to 10 devices and deliver download speeds of up to 76 Mbit/s. “We want to overwhelm other companies in terms of speed,” he said.

Frost & Sullivan’s Einstein said Softbank was trying to reposition itself as the “fastest network” after four years as Japan’s sole iPhone supplier.

Softbank’s shares plummeted in September when the news broke that rival KDDI Corp. , Japan's second-largest mobile operator behind NTT DoCoMo Inc. (NYSE: DCM), would also be selling the iPhone. It is already feeling the strain from voice service price cuts KDDI has made. KDDI will begin selling the new iPhone 4S on Oct. 14, reported Reuters.

— Robert Clark, freelance editor, special to Light Reading