Softbank launches «pseudo TD-LTE» services

Caroline Gabriel/Wireless Watch

The downside – until Softbank buys or refarms further spectrum for conventional FD-LTE, it is using a system called AXGP, which is unique to Japan.

The OFDMA-based technology was conceived as a data upgrade for the low cost, voice-oriented PHS system, which was deployed mainly in Japan and China. When China decided not to upgrade PHS, but instead to harness the spectrum for 3G and TD-LTE, AXGP was, to some extent, converged with the similar Wimax and TD-LTE platforms. So much so, according to Softbank, that its network is now “pseudo-TD-LTE”, and “highly compatible” with that standard, itself gaining ground in China, India and the US.

Softbank will still have to work closely with specialist chip and device makers, such as Altair and Seiko, to ensure it has gadgets for its network – something Japanese operators are well used to, but which has become a declining aspect of their model since the country's consumers have belatedly fallen in love with generic smartphones. Softbank itself benefited from that trend as it had the iPhone exclusive for several years, before KDDI also gained the Apple handset last year.

That put pressure on the third cellco to offer another distinctive service, and it has gone live, in Tokyo, with its “Softbank 4G” proposition, initially with a Wi-Fi router from Seiko promising peak download rates of 76Mbps, a speed which will increase to 110Mbps in future. The service will cost $70 per month, or less for existing Softbank smartphone customers. It will be available at first only in major cities, with users falling back to 42 Mbps HSPA+ in non-coverage areas.

Although Softbank is using an unusual technology, which will have severe limitations in terms of devices and cost efficiencies, it gained its 2.5-GHz spectrum at low cost compared to most 4G licences, and has been able to use it to move into 4G earlier than would otherwise have been practical - at a time when main rival NTT DoCoMo already has live LTE (and KDDI has its Wimax-based UQ venture plus its own LTE plans). And firms which have worked on AXGP, such as chipset maker Altair, claim it has superiorities over standard LTE in some respects, such as capacity, scalability and self-installation of CPE.

The spectrum came Softbank's way when Japan‟s PHS operator, Willcom, ran into trouble in 2009. That saw Softbank injecting ¥3bn ($33.1 million) into a new entity created to take over Willcom's 30 MHz of 2.5-GHz spectrum, which had been earmarked, during earlier auctions, for PHS upgrade (a second 2.5-GHz licence was won by KDDI-backed consortium UQ, which runs a Wimax service in cities).

Softbank owns the new company along with equity fund Advantage Partners, which also bailed out the legacy PHS operation, investing ¥300m in early 2010 along-side some state funding. Willcom was controlled by the Carlyle Group when it filed for bankruptcy protection. “The fact that Softbank has been able to acquire hard-to-come-by wireless frequency for a mere ¥3 billion is positive,” said Credit Suisse in a research note at the time.

Meanwhile, AXGP will continue to grow closer to TD-LTE until the differences between the two really are unrecognizable. Its industry body, the XGP Forum, has worked on it in partner-ship with the TD group in China and the AXGP baseband and air interface both conform to the 3GPP standard for TD-LTE. Specialist chip suppliers like Altair and Wavesat (now Cavium) were initially the main sources of silicon but the Seiko device has a Qualcomm baseband while Huawei and ZTE have supplied the base stations, Ericsson the packet core and Alcatel-Lucent the backhaul.

While Softbank may be sticking, at least nominally, with AXGP because of the stipulations of its licence, this will be seen as less of a burden in Japan than elsewhere, some argue. Marc Einstein, an analyst at Frost & Sullivan, told LightReading Asia: “Japan loves its own standards, going back to [2G] PDC. But I'm not convinced it's not LTE TDD under another name.”

Meanwhile, Japan's fourth operator, eAccess, has awarded contracts to Ericsson and Huawei to deploy a multimode solution for W-CDMA and LTE, enabling the operator to use the same frequency band for both services. Ericsson will provide full turnkey roll-out, network optimization and the evolved packet core. Huawei is supplying a 3G/LTE network which is the first con-verged RAN to be rolled out in the 1.7GHz band, using its SingleRAN technology plus core products.

Related content