Wimax Forum warms to LTE

The world of TDD spectrum and technologies has been in flux ever since Wimax lost its bid to be the only standard in unpaired frequencies in the face of the rise of LTE – complete with the previously neglected TDD flavor.
The story is well known – the initial Intel-driven push behind Wimax as the first 4G platform; followed by the mobile industry marshalling its forces to accelerate LTE progress and put its weight behind TD-LTE too. That saga came to its logical conclusion last week when the Wimax Forum confirmed that it would embrace other air interfaces such as TD-LTE in its future architecture.
But that does not mean plain sailing for the newer standard. Although definitely entering the mainstream as a future option for many carriers, not just those migrating from Wimax, it is less developed than its FDD cousin in terms of device ecosystem and equipment cost. Those will develop as critical mass is reached, but that goal received a setback last week when two major adopters pushed back their plans.
Aircel in India will not deploy TD-LTE until next year, while Clearwire has been forced to reduce some of its roll-out targets. Aircel is unlikely to start launching 4G services until into its next fiscal year, which starts on April1 2013… [and] Clearwire will now install only 2,000 TD-LTE base stations by the end of June 2013, well down on the planned total of 5,000.
Wimax and LTE
These setbacks are not fatal, but they do postpone the day when there is mass availability of TDD or dual-mode devices outside the Chinese bands – where of course, TD-LTE's biggest cheerleader China Mobile is creating a volume base all by itself with its huge “trial” network. And other former Wimax players are moving quickly too, notably Yota in Russia, whose LTE network is hosting 4G services for several larger cellcos, and which has started to implement certain features of the LTE-Advanced standard.
This will combine the FDD and TDD strands to a far greater extent, and introduce a broad range of new functions, many of them optional. Early adopters are particularly interested in carrier aggregation and this is the feature which Yota has deployed in selected base stations in Moscow, working with Huawei.
The appearance of LTE-Advanced will squeeze the remains of Wimax still further in the mobile market and its trade body, the Wimax Forum, is acknowledging the inevitability of carrier migration to LTE now. It has opened its platform to include elements of the TD-LTE standard it once sought to fight off and its “Wimax Advanced” framework will support various air interfaces. Although Declan Byrne, president of the industry body, insisted this would not “open the flood-gates of a migration from Wimax to other technologies”, in effect this was an acknowledgement that, at least in the core mobile broadband space, that shift is already under way.
The Forum confirmed reports that its board had unanimously approved a proposal to add TD-LTE support to the upcoming Wimax 2.1 specifications, at a meeting a few weeks ago. That spec will be ready in draft form by year end and ratified in early 2013. The Wimax Advanced platform will effectively provide an IP-based framework which can support multiple air inter-faces including its own 802.16 and the 3GPP TD-LTE standards.
Operators with software programmable dual-mode base stations would be able to support both Wimax and TD-LTE devices simultaneously – something some carriers are already implementing, but this would allow for a standards-based approach.
The aim will be to make a dual-mode Wimax/LTE platform simpler and more cost effective, which would prolong the opportunity for multimode device and chip suppliers and help operators to migrate in a gradual way. Currently mobile Wimax providers are under pressure to move swiftly to LTE-only to tap into the larger device availability. However, to take advantage of the changes, they will need to have invested in flexible infrastructure with a view to eventual LTE coexistence, rather than older, single-mode kit.
Wimax, after an early head start, was overtaken by the huge mobile industry weight behind LTE.
The significant opportunities for Wimax now lie outside the mobile world, in vertical sectors such as smart grid and aviation, and in its traditional sphere of fixed wireless access.