WiMax Limitations Exposed
Part of the promise of WiMax is that it will be more than just a fat, wireless pipe -- that with WiMax, service providers could enable applications like VOIP and even wireless video services. But the code that would enable such applications is not a mandated part of the initial WiMax profile from the WiMax Forum, vendors say.
In fact, the WiMax profile only defines the transport layer to be used in base stations and customer premises equipment (CPE) and lets vendors and operators chose what they want to use to implement higher-level functions like VOIP.
"We ask for the base line, getting the base station and the CPE to work together," confirms Mo Shakouri, VP of marketing at the WiMax Forum.
The Institute of Electrical and Electronics Engineers Inc. (IEEE) 802.16d standard that WiMax is based defines both the physical (PHY) and media access control (MAC) layers used in the metro-area technology. The 802.16d MAC layer sports QOS (quality-of-service) capabilities that can enable voice services and support for authentication and link privacy security (see WiMax Guide).
So, while WiMax supports QOS and security, it does not mandate higher level application support, such as support for the session initiation protocol (SIP) for VOIP. The Forum is, though, planning an "applications plugfest" to demonstrate the kind of services that can be offered over WiMax later this year, Shakouri adds.
So, while there is a lot of hype and hullabaloo about WiMax supporting VOIP right out of the box, it will only do so if a vendor builds that capability into its product. It is not a standard feature.
Some equipment vendors do not see this as issue. Startup AirTegrity Wireless Inc. has just announced a product that it is calling "WiMax in a box," which adds security features, voice support, and more, to the basic profile (see AirTegrity Debuts 802.16 Kit).
AirTegrity's CEO/CTO, Greg Phillips, tells Unstrung that he belives that companies in the WiMax market will be able to compete on the different feature sets they offer to operators. "It's a key differentiator," Phillips says.
But some vendors worry that performance-enhancing features have been left by the wayside. Chad Pralle, strategic marketing director at fixed wireless stalwart SR Telecom Inc. (Toronto: SRX) worries that some of the initial WiMax chipsets he has seen from component vendors don't even support a feature called "sub-channeling," since it is only an optional part of the spec.
Sub channelization concentrates radio signals into a few narrow bands. The WiMax Forum describes it as a useful technology for extending the reach of radio signals, improving in-building penetration, or lessening the power consumption of CPE kit, especially in non-line-of-sight (NLOS) implementations.
SR Telecom is planning to introduce a WiMax box of its own in the first quarter of 2006, but Pralle is hoping to try and manage people's expectations about what WiMax can do and when it will arrive on the market.
"One of things we've been doing is telling the truth about WiMax and when it will arrive," he says.
In fact, although Pralle thinks that standardized metro-area wireless is a good thing, he reckons that the reality of WiMax will not match current expectations.
And recent delays to initial WiMax tests are just the tip of the iceberg for the Forum, the SR guy says (see Wise Words on WiMax). "The next six- to 12-month period is going to be very bad for the WiMax Forum," Pralle claims.
— Dan Jones, Site Editor, Unstrung