The ITU's acceptance of WiMAX as belonging to the IMT family of technologies - effectively designating it as a mobile technology and making it eligible for deployment in 3G spectrum - is an important milestone and should not be played down, not least because WiMAX proponents now have a direct link to much-needed spectrum in key bands, such as 2.6GHz.

At its recent Radiocommunication Assembly in Geneva, the ITU decided that the IMT-2000 3G family was to be expanded to six terrestrial radio interfaces, with the addition of OFDMA TDD WMAN as a specific subset of IEEE 802.16e (mobile WiMAX). It also decided that IMT Advanced would be the official name for 4G.

"One of the fundamental things you need is spectrum access, and there is no better way to secure it than to have this recognized internationally," Paul Senior, CTO of Airspan, told Informa Telecoms & Media. "WiMAX was originally a fixed development of 802.16, and in most places in the world there are restrictions on using fixed technologies in the mobile space.

"The problem was deciding on which bands to use. The 2.5GHz was always interesting, because it was a new spectrum allocation in many countries. In most cases, regulators took back those bands."

WiMAX skeptics have said that the ITU decision was not that significant, since technology neutrality is well on its way to being established as a de facto policy across the EU. But such an opinion is misjudged, for two reasons: First, despite technology neutrality, many regulators were restricted by spectrum awards they had already made, since it's difficult to reallocate spectrum. And second, without IMT certification, WiMAX wouldn't have been considered a viable mobile technology. It would be viewed as a fixed technology and would therefore be unable to compete with 3G.

Waiting for technology neutrality would have taken too much time, and many in the industry are still not prepared for it, Senior said.

"Regardless of technology neutrality, ITU recommendations are given great credibility," Roger Marks, senior vice president of NextWave Broadband, told Informa. "And I believe that much of the world is a long way from technology neutrality at the regulatory level."

In Europe, the 2.5-2.69GHz bands were originally considered to be IMT-2000 extension bands, part of 3G. In both the UK and Norway, technology neutrality for spectrum is going ahead, and other European countries look to be going down a similar path.

"Ultimately, the choice for the WiMAX Forum was to either gain acceptance into the IMT family or get rid of that IMT designation altogether," Senior said. "Now the excuse that WiMAX technology is not in the IMT family has been removed, a major barrier to entry has also been removed."

Spectrum-deployment concerns

Still, Ovum says that just because mobile operators can deploy mobile WiMAX using currently owned 3G spectrum, they will not necessarily do so, for two reasons.

The first is that "mobile WiMAX profiles for 1.9-2.1GHz bands have not been defined," the research firm stated. "Given that the WiMAX Forum is already struggling with the certification process for wave-one products in 2.3/2.5/3.5GHz bands, there is no chance to see any additional profiles being defined in a near future."

The second involves spectrum requirements for WiMAX deployments. "To be efficient, the WiMAX Forum suggests operators have access to at least 20MHz, though 30MHz is considered to be far better," Ovum stated. "Mobile WiMAX only supports TDD, and as of today, 3G operators in Western Europe own 5MHz TDD spectrum on average."

Senior says operators will need at least 30MHz of spectrum for a WiMAX deployment. "The 30MHz was decided three years ago, and now we're saying that around 70MHz is really much better," he said, adding that there was no rush to include the 1.9-2.1GHz bands for WiMAX, since the 2.5GHz band is ideal for the technology. Moreover, Africa and Europe have extensive WiMAX deployments in the IMT Advanced 3.4-4.2GHz bands, which is sufficient for the time being.

In fact, operators that deploy WiMAX in future IMT Advanced bands will have an incentive to choose the next iteration of WiMAX - 802.16m, which is expected to be backward-compatible with 16e - as their 4G technology.

TDD vs. FDD

Most IMT2000 technologies are based on frequency-division duplexing (FDD), since more technologies use FDD than time-division duplexing (TDD). The WiMAX Forum is beginning to campaign for the allocation of more TDD spectrum, which it says is better for data-centric services. "We can expect a FDD profile to be included in WiMAX in around six to eight months' time," Senior said. "But the importance of the TDD-vs.-FDD issue is really all about whether you believe the future of services is going to be data - and not simply pushing data services to smartphones - or voice-centric. The business today remains very voice-centric, and to a certain extent there is no need for significant data infrastructure."

"In the future, there will be more TDD spectrum, as it becomes more efficient," ZTE USA's Sean Cai told Informa. WiMAX will benefit from economies of scale, device interoperability and, crucially, roaming capabilities as a result of the adoption, he adds.

Globally, Senior says, more than 1,000 trials are being conducted. And although most have been in fixed WiMAX, the arrival of mobile WiMAX is changing the situation.

Meanwhile, the appearance of two previous skeptics - Vodafone and Cisco - on the WiMAX bandwagon demonstrates the major steps that the WiMAX Forum has achieved in garnering acceptance for the technology. Vodafone is deploying a WiMAX network in Malta, and Cisco, two years ago a fervent WiMAX skeptic, last week announced that it had agreed to acquire WiMAX-equipment manufacturer Navini Networks.

Mohammed Hamza is senior reporter for Global Mobile

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