Mobile operators may be counting on LTE (Long-Term Evolution) technology to offer high-speed mobile data access in coming years, but WiMax services will arrive first, promising to shake up the wireless data market in the process.

WiMax offers high-speed Internet access over a wide area and comes in two versions, a fixed-wireless version and another for mobile. The technology, often likened to Wi-Fi on steroids, has two advantages over LTE: it's available today and is free from the hefty royalty charges required for 3G (third-generation) mobile devices and equipment. By comparison, LTE has another two to three years to go before it can be deployed and, because the radio uplink uses CDMA (Code Division Multiple Access), device makers will have to pay substantial royalties to Qualcomm.

"They charge a 5 percent royalty on the handset or devices, and that's on the retail side...Behind the door, they're charging anywhere from 15 to 30 percent on the chipsets," said Bill Rojas, director of communications research at IDC Asia-Pacific, adding that WiMax backers have agreed to a much lower royalty for using the technology.

While lower royalties and the earlier rollout of commercial services gives WiMax an edge over LTE, there are still obstacles that must be overcome before the technology can be widely deployed.

The immediate challenge WiMax faces is product interoperability. WiMax Forum, the industry group that oversees the certification process, has only approved the interoperability of a handful of WiMax products designed to operate in the 2.3GHz spectrum. This frequency is used in South Korea while most other markets expect to use the 2.5GHz to 3.5GHz spectrum bands.

In addition, the certified products are based on the Wave 1 version of WiMax, which does not support MIMO (Multiple-In, Multiple-Out) antenna technology, or other advanced features found in the Wave 2 version of WiMax that operators, including those in Korea, plan to deploy. As a result, the certified products announced by WiMax Forum are largely irrelevant to wider adoption of the technology.

WiMax Forum will not certify the interoperability of Wave 2 WiMax products until the second half of this year, at the earliest - nearly a year behind schedule and after Intel releases the first Centrino 2 products in June. That timing suggests that the number of Centrino 2 laptops that ship with WiMax this year will be relatively low, but nevertheless widespread availability of the technology is not far off.

Intel sees 2008 as the year when WiMax will start to appear in computers, such as a WiMax-equipped Asustek Computer Eee PC that Sriram Viswanathan, vice president of Intel Capital, the chip maker's investment arm, and general manager of the company's WiMax Program Office, showed off in Singapore.

"We have a variety of these devices. Not all of them will be launched on the first day, but the fact is during the second half (of 2008) you will see a plethora of devices," Viswanathan said in a recent interview.

Intel doesn't expect shipments of WiMax-equipped computers to hit high volumes during 2008, largely due to the limited availability of WiMax services. As more networks come online in 2009, shipment volumes will rise but the technology will not become a standard feature on computers for some time, Viswanathan said, predicting that might happen in 2011 - about the time that LTE rollouts are just getting started.

The current lack of certification for WiMax interoperability has some operators nervous. For example, Taiwan's First International Telecom (Fitel) said a focus for the upcoming launch of its WiMax services is to reassure users their WiMax devices and add-on cards will not only work on Fitel's network but also on other WiMax networks.

"We want people to be able to roam among WiMax networks, not just in Taiwan but also foreign visitors and when Taiwanese go overseas," said Charlie C Y. Wu, Fitel's president.

Client devices aren't the only products where interoperability is critical. Transmission equipment from different vendors must also work together.

"Operators don't want to buy equipment from a single vendor for many reasons," said Mike Ropicky, a senior director of product, operations and marketing at Motorola. One of the most important is to hedge against the possibility that an equipment vendor's technology will fall behind its competitors, leaving the operator without the ability to roll out future upgrades to its service, he said.

To fill this gap in certification and reassure both users and operators, equipment makers like Motorola and LG-Nortel have embarked on their own certification programs, testing the interoperability of their products with those from other vendors, including client devices. This helped clear the way for initial trials and deployments of WiMax, and should help smooth the way forward for the rollout of more WiMax networks.

Besides the promise of broadband Internet access over large areas, WiMax promises to shake up the competitive landscape and could unseat large mobile operators from the commanding positions they now hold.

Most major mobile operators have said they won't deploy WiMax, choosing to wait for LTE to become available before they overhaul their networks and offer faster data speeds. They have little choice due to the high investments they've already made in 3G and related technologies - investments that in many cases have yet to be fully recovered.

"Operators that have spent a significant amount of money on 3G will have a hard time justifying it to their shareholders now they're going to put more money in a completely new construction," Intel's Viswanathan said.

Designed as an upgrade for 3G and HSPA networks, LTE will offer greater bandwidth than current mobile technologies. For example, NTT DoCoMo, Japan's largest mobile operator, announced last month that its LTE trials had achieved a 250M bits per second (bps) download speed. The high-speed technology could start appearing in its networks by 2010, the operator said.

Vodafone, one of the world's biggest operators, is also backing LTE. Trevor Gill, head of networks at Vodafone Group R&D, reportedly told attendees at a UK conference the technology was likely to be selected as a future upgrade for the operator's HSPA networks, even as it continues to watch WiMax closely.

Not all cellular operators plan to skip WiMax; smaller players see the technology as a way to gain ground on larger rivals. For example, Sprint in the US and KDDI in Japan both have plans to offer WiMax. These companies and others like them, called "attackers" by industry watchers, see the earlier availability of WiMax as an opportunity to gain a competitive advantage by being the first to roll out a wireless broadband service.

"With WiMax, what you're going to see is a lot of attackers go out there and deliver a service," said Peter MacKinnon, chairman of LG-Nortel. "That's what will define the WiMax market."

WiMax will also find a foothold in emerging markets, where broadband Internet penetration remains low. In these markets, the technology will be used as a fixed-wireless service, providing wireless Internet access to a fixed location, such as a home or office, rather than a service designed for mobile users.

However, operators in these markets will likely use the same version of WiMax, called 802.16e, that was developed for mobile users, because economies of scale will mean these products end up being cheaper than the fixed-wireless version of WiMax, known as 802.16d, said Margaret Rice-Jones, CEO of Aircom International, a company that helps operators plan WiMax networks.

"It also gives them the option in the future of moving to a mobile network," Rice-Jones said.

(Dan Nystedt, in Taipei, contributed to this story.)