Can WiMax clear the roll-out barriers?

4. How fast can WiMax roll out to millions of devices?

"Mobile WiMax holds promise, but the real question is will we see actual consumer electronics devices?" asked Zeus Kerravala, another Yankee Group analyst.

Redman said Xohm's potential for success is built partly on a vision of low-cost devices that will sell for under $100, such as an inexpensive iPhone with a larger screen. "But that will be difficult to pull off," he said.

West said 50 million or more devices will be needed in the next three years to run over the Xohm WiMax network. He said five laptop makers are already on board to provide internal WiMax chip sets for laptops, but he would not give any names. Sprint selected the infrastructure vendors for Xohm because they make mobile devices, and one of them, Motorola, even demonstrated working alpha WiMax-enabled wireless phones on the Chicago River cruise. Intel also demonstrated a laptop with an internal WiMax chip and said it is working with Nokia to provide handhelds that incorporate an Echo Peak module with combined WiMax and Wi-Fi capability, using the draft 802.11n specification.

Inevitably, there is a relationship between having enough devices running WiMax chips and drawing enough market interest that customers will buy devices running WiMax in bulk, analysts noted. It might not be all that different from the past, but with WiMax, and especially with Xohm, the timetable seems more pressing than before because of a variety of competing wireless technologies, especially in the U.S. and other developed countries.

5. How does WiMax compare with the competition?

Ultimately, the fifth obstacle concerns competition and which of the WiMax providers will win with it compared with alternative technologies backed by other vendors.

On the network equipment side, Motorola, Intel and Nokia might seem to have a lead with their connections to Xohm. However, Nortel Networks, which did not win a role as a WiMax equipment provider for Xohm, still sees a big market for WiMax gear and has several deployments under way. WiMax World also featured dozens of small vendors offering WiMax components. These included full-blown systems with antennas, gateways, client chip sets and software supporting it all.

The real unanswered questions are how well Xohm can do in the next two years before providers begin work on a pathway to Long-Term Evolution technology for broadband wireless, Ayvazian said. LTE, in some fundamental ways, is similar to WiMax, he noted, since both technologies rely on multiple-input, multiple-output (MIMO) antennas and orthogonal frequency modulation to send signals.

In another competitive comparison, the US now has HSDPA: AT&T has begun rolling out its BroadBandConnect 3G network operating on GSM. AT&T advertises the average downlink speeds in the range of 400 kbit/s to 700 kbit/s, but the potential of such networks is theoretically more than 14 Mbit/s, Redman said. Still, he bet that HSDPA might run only as fast as WiMax in real-world networks.

Redman noted there is less latency, or delay, with WiMax technology, which enhances its usage for voice technology. WiMax also uses the available spectrum more efficiently, a factor that will matter to the carriers providing the networks and to end users.

However, as with many radio technologies, there are many variables that affect what an end user can accomplish wirelessly, including the efficiency of the client device he carries, Mathias noted. In a WiMax network, West said many channels could be added to an antenna in crowded zones to bump up performance for a client device. However, in a separate interview, Mathias retorted, "Sure, but what happens when you add many, many more users?"

In addition, Sprint Nextel, in collaboration with Clearwire, has control of licenses in the 2.5 GHz spectrum in the US for WiMax. That control is what some experts see as a clear-cut advantage over any carrier seeking to enter the WiMax market there.

Given spectrum licensing and competing broadband technologies, Redman predicted late in 2006 that in 2011, there will be fewer than 10 international wireless operators deploying WiMax.

However, Ayvazian said the events and enthusiasm of WiMax World helped accelerate Yankee Group's latest prediction of users for WiMax. The last projection of 7 million to 8 million WiMax subscribers in the US for 2011 and 27 million subscribers worldwide should be moved to a year earlier, he said, to take into account Sprint's partnerships with Clearwire and Google.

"We're at the inflection point of how this market's going to jump forward," he said.

It's obvious that there are many questions, obstacles and potential obstacles for WiMax. Yet there is so much promise that while analysts are unwilling to be too optimistic, they aren't too pessimistic in predicting how successful it will be.

How well Xohm performs in its first markets in Baltimore/Washington and Chicago in December should answer many questions.