A Dry Run for Mobile WiMAX

It's hard out there for an emerging technology. First there are the existing and often radically different network architectures to displace. Then there is the almost unavoidable hype cycle, a symptom of the telecom industry's constant need to feel like something better is always just over the horizon. That results in market confusion, which is usually exacerbated by unfamiliar developmental steps, which typically turns into doubt and disappointment. When a new technology finally gets deployed, the arc of expectation usually is at a low point, mercifully allowing for some early-stage performance hiccups. If those get ironed out and the technology starts to evolve and be accepted, it just may have a chance.

The WiMAX community knows that story all too well — knew it, in fact, from even before the story started for WiMAX and thus tried to take steps to avoid it. From the outset, the WiMAX Forum attempted to educate the industry not just about what WiMAX ultimately would be able to do, but also how it would get there. That included very specific timelines for how various versions of the technology would evolve and a very specific and stringent process for certification of equipment by the WiMAX Forum — a seal of approval that would communicate to the industry that gear was interoperable and market-ready.

For the most part, the WiMAX Forum's efforts have helped manage the industry's expectations about WiMAX, at least in terms of when its different incarnations would come onto the scene and what those versions would add to the mix. Of course, there's no managing — let alone stopping — the technology hype cycle, which is the leading contributor to inaccurate perceptions and ultimate disappointment. There also is no way to wholly prevent wrong interpretations of various steps along the way — like the interoperability plugfests that precede certification testing, which often are perceived as races or contests rather than just important steps in the process of managing the introduction of different versions of WiMAX.

“In the space of a little more than a year, the awareness of WiMAX has skyrocketed,” said Dan Coombes, chief technology officer for Motorola. “It's important to get a message out that this technology does work and that the equipment is interoperable.”

Indeed, the WiMAX community diligently continues to try and keep the industry educated and informed about the evolution of WiMAX and the significance of its various stages. And the WiMAX Forum had another opportunity to do that in September, when 21 WiMAX equipment manufactures and three test vendors (see texbox on this page) convened at a Bechtel Telecommunications lab in Frederick, Md., for the industry's first plugfest for 802.16e-2005 Mobile WiMAX equipment. The timing of that event was made more significant by Sprint's earlier endorsement of Mobile WiMAX technology, complete with a $3 billion deployment promise and the designation of Mobile WiMAX as 4G, or fourth-generation mobile.

Wireless Review talked to several participants in the recent plugfest in an effort to glean more intelligence about the significance of the process and the role it plays in the overall evolution of WiMAX technology.

It's important to understand what a plugfest is meant to accomplish: It is not a formal or required step in the certification process for WiMAX, but rather a voluntary event at which vendors that feel their gear is close to certification can gather to test its ability to interoperate with other companies' equipment. Interoperability is one of the characteristics on which certification from the WiMAX Forum is based, so plugfests provide a live opportunity to pre-test that capability with other companies, without the pressure of official testing process.

“It's an informal environment,” said Jeff Orr, director of marketing for the WiMAX Forum. “Companies can come together, and they're not making commitments. Most of the equipment they bring is not announced yet, and it's a private setting.”

That informality is critical for plugfest participants because the same is not true of the actual certification testing process.

“In the certification lab, you get one shot,” said Sai Subramanian, vice president of product management and strategic marketing for Navini Networks. “If it doesn't work, you have to get back into the queue.”

During plugfests, on the other hand, vendors may indeed make some alterations to their equipment based on how it interoperates with other gear. That can be done on the fly during the dry-run testing process.

“The standard contains a lot of options, and it's also open to interpretation,” Motorola's Coombes said. “The plugfest is to verify that the standard was interpreted correctly by the vendor companies.”

“It's making sure that whatever you understood from the standard and the system profile is the same,” said Bernard Aboussouan, vice president of marketing and business development for Sequans. “In case you didn't understand it the right way, you need to make a change. Better to make that change earlier in the process.”

Since interoperability is critical, plugfests represent the final opportunity to adapt.

“We go into these events with a vision that we have to change,” said Byron Young, vice president of marketing and product management for Adaptix. “You assume that nothing works.”

The plugfest held in September was the first for the mobile version of the WiMAX standard, and because of the mobility aspect, the testing process is more complex and involves many more tests than for other versions of WiMAX. For that reason, said Orr of the WiMAX Forum, more automated test equipment and software is required.

The plugfest process itself involves a lot of work being done in parallel, Orr said, with pairs of companies joining together to conduct tests in a pre-defined order and continuing through the testing schedule.

“They proceed through the test suites until some error occurs, and then they try to remedy that on-site,” Orr said. He compared the process to the bracketing system in a sporting event: After proving interoperability with one vendor (or making adaptations to attain it), vendors move on to the next participant, and so on. “The idea is to maximize the opportunity every vendor has to work with as many other devices as possible,” Orr said.

According to a white paper published by the WiMAX Forum, “A vendor is considered to be interoperable once they have demonstrated that their hardware is able to send and receive packets of data with two other vendors involving base stations and subscriber stations for a selected certification profile.”

Cetecom Labs, which is based in Malaga, Spain, and operates the lead certification testing lab for WiMAX technology (the other is operated by Telecommunications Technology Association, or TTA, in Seoul, South Korea), also was one of the companies that provided test equipment for the September plugfest. Jose de la Plaza, wireless laboratory manager of Cetecom Spain, said plugfests usually reveal several different interpretations of the standard and are critical in helping vendors work out final links to one another's gear.

“Typically, one week in the plugfest is equal to several months of development in the labs,” he said.

Another benefit of both plugfests and final certification is that service providers that purchase WiMAX equipment don't have to test the gear in their own labs or do field trials if they choose not to because they can be assured that the equipment is interoperable.

“There's not a requirement for operators to re-run those tests,” Orr said. “The intent here is to provide a baseline of functionality that network operators don't have to go and replicate.”

hat makes plugfests good gauges of WiMAX readiness, said Fernando Hardasmal, deputy general manager of Cetecom Spain. “Plugfests are a very good indication of what's going to happen in the market,” he said.

The events also can play a major role in shaping the industry's perception about a technology — a critical function for WiMAX in particular.

“Plugfests are an important way for us to demonstrate to our customer base that we're tracking our certification progress,” Navini's Subramanian said.

“It also shows who's really in play,” Motorola's Coombes said. “It really is a confirmation to the industry that these companies are truly involved because they're bringing equipment, and they're committed to making it work. It gives operators assurances that there will be equipment available from multiple companies, and that it's interoperable.”

The presence of multiple companies involved in plugfest events begs the question of competitive rivalries and whether they come into play in the process. The WiMAX equipment manufacturers interviewed for this article generally agreed that although there occasionally are some competitive moments, everyone involved typically understands what's involved and why cooperation is critical.

“Whether you're a smaller company like Soma or one of the bigger ones, nobody can have all the combinations of base stations and CPE,” said Jonathan Jaeger, director of business development for Soma Networks. “It's also a great opportunity for us to check out the test equipment vendors.”

“As you go through the process, everyone realizes you're not going to get anywhere unless you work together,” said Young of Adaptix. “There's a practical reality that no one can do it alone.”

The ultimate goal of WiMAX Forum certification also makes cooperative participation a given, said Carlton O'Neal, vice president of marketing for Alvarion.

“Remember, interoperability is the ultimate end game — so hiding the ball doesn't help anyone,” O'Neal said. “From the beginning with the forum, there was a shared purpose. The shared purpose carries the day, as does the engineering mentality, for the most part. It's congenial.”

MOBILE WIMAX PLUGFEST PARTICIPANTS
(September)

Accton Technologies
Adaptix
Airspan
Alcatel
Altair Semiconductor
Alvarion
Beceem Communications
Cetecom-Aeroflex
GCT Semiconductor
Intel
M/A-COM
Motorola
Navini Networks
PicoChip
POSData
Runcom
Samsung
Sequans Communications
Soma Networks
TTA Labs
Wintegra

TEST EQUIPMENT VENDORS:

Cetecom
Invenova
Rohde and Schwarz

Source: WiMAX Forum

OBJECTIVES OF A PLUGFEST

Identify where there may be differing standards interpretations that must be resolved.

Identify interoperability problems, which may be firmware- or software-related.

Encourage open and unambiguous technical discussions of the test scenarios and the standard with a means to correct them.

Prepare a vendor to submit their products for formal certification testing.

Continuously improve the quality of interoperability testing to ensure a viable WiMAX certification process.

Make improvements for implementing future group testing venues.

Source: WiMAX Forum

TELEPHONY'S GUIDE TO WiMAX

For the past three years, Telephony has been covering WiMAX — specifically the certification process — in our supplement, Telephony's Guide to WiMAX. If you've missed an issue, you can find them under the supplement section of our Web site.
www.telephonyonline.com/supplements