There is sometimes a fine line between luxury and necessity, and to be realistic, Wi-Fi is still more the former than the latter. Increasingly, it’s being deployed in the workplace and in public places, and the truncated rhyme of a word might even be surfacing in everyday usage outside of technology industries. Yet, if you approached the average business user or consumer and said you would offer them the ability to conduct voice calls and videoconferences over Wi-Fi, many of them would ask the same question: How well does it work?
Quality might be the most important gating factor between luxury and necessity. Wi-Fi may be getting close to drifting across that fine line, but it must be capable of carrying the weight of our expectations for quality along with it. The emerging 802.11e standard will help Wi-Fi bear that load.
“People still think about Internet access without thinking about the applications,” said Robert Holtz, CEO of Zeros and Ones, a company currently developing a Wi-Fi peering service and other products and services that could take advantage of 802.11e. “But, you need quality to take advantage of the greater applications.”
The 802.11e standard for multimedia quality of service (QOS) over Wi-Fi likely will gain full draft approval from the IEEE at an 802.11e Working Group meeting scheduled for March. However, enough of the standard was finished by late last year that it gave the Wi-Fi Alliance some fodder to develop its own interoperability certification and gave vendors some food for thought as they develop the next-generation of Wi-Fi equipment and devices.
On a technical level, a QOS standard for Wi-Fi might seem unnecessary for the average residential consumer because current Wi-Fi access solutions allow for user data rates of anywhere between 11 Mb/s and 54 Mb/s, which will prove more than enough for any one application.
“A lot of [small office/home office] providers of Wi-Fi are just throwing up Wi-Fi coverage for people, and you’re supposed to be getting 11 Mb/s, but are you getting 11 Mb/s?” asked Graham Celine, vice president of marketing at Azimuth Systems, a vendor of wireless LAN test equipment. “The truth is most of these users will never know anyway.”
Azimuth, which already markets equipment for testing wireless LAN performance and recently incorporated QOS testing capabilities, knows what users might not want to know about access point performance.
“We have seen some pretty hairy stuff, some pretty bad performance from some of the industry’s leading wireless LAN platforms,” Celine said.
However, in the enterprise market, deployment of Wi-Fi infrastructure is rapidly becoming a serious element of corporate IT strategies, and many enterprises are expecting to eventually evolve the traffic they transport over these networks beyond data to voice and even video. With that evolution, corporate IT managers, as well as service providers, will want services or mechanisms that will allow them to prioritize some traffic types over others.
Proxim, one of the leading suppliers of Wi-Fi access points and management software to the enterprise market, senses a change in attitude about Wi-Fi QOS.
“This is due to a combination of things,” said Lynn Lucas, vice president of product marketing for Proxim. “There is a new feeling that Wi-Fi as a technology is ready for prime time and that a lot of the security concerns that people had before about deploying Wi-Fi are gone now. We’re seeing the emergence of voice as an application, but voice is not even deployed that widely yet. It is also that enterprise customers are becoming more comfortable with Wi-Fi, deploying it more broadly and beginning to get more serious about upgrading their architectures and expecting more from them.”
As Wi-Fi deployment and usage is increasing, there are often several users per access point eating up that bandwidth. This is fine if the only application is Internet access, but as voice and video applications over Wi-Fi become popular, companies will have to answer the question of how well those applications will work through occasionally congested access points.
With that in mind, the development of 802.11e couldn’t be more timely. After initially launching a Wi-Fi QOS effort more than five years ago, the IEEE 802.11e Working Group made significant progress last year. The result will be a standard that addresses traffic prioritization schemes in a Wi-Fi infrastructure using the Enhanced Distributed Channel Access (EDCA). The full draft approval, expected in March, also will include details regarding battery life and power management for the increasing number of Wi-Fi device types expected to emerge with the development of new voice and video applications.
Some aspects of the full 802.11e standard won’t have terribly important implications for the entire industry, so most of the work is done, Celine said.
“Standards development is such an open process that anyone can suggest anything and get it included as a line item in the standard,” he said. “Everyone’s agreeable to these suggestions because they just want to move the standard along, but not everything in the standard will be that important to the whole industry.”
The first-phase approval couldn’t have come fast enough for a fast-maturing Wi-Fi market, and sensing the market’s urgency, the Wi-Fi Alliance, the group that interprets standards and promotes Wi-Fi equipment interoperability, used the first-phase draft to develop its own market-friendly QOS certification called Wi-Fi MultiMedia (WMM).
In announcing the first WMM certifications late last year, Frank Hanzlik, managing director of the Wi-Fi Alliance, said, “The demand for Wi-Fi [consumer electronics] product connectivity is expected to grow significantly, and WMM will provide a strong foundation for that growth.”
The first WMM certifications primarily revolved around access point reference designs and card bus adapters from chipset vendors such as Broadcom, Atheros Communications, Phillips and others.
The Wi-Fi Alliance also has posted a white paper on its Web site that outlines the technical details of WMM and its relationship to 802.11e.
“Large portions of the standard are already stable, so WMM was the Wi-Fi Alliance’s effort to get some of the standard out there because it’s something that the enterprise market can take advantage of now,” said Proxim’s Lucas.
The importance of 802.11e and WMM are difficult to overstate. For the first time, there will be such a thing as classes of service for Wi-Fi. EDCA allows traffic to be prioritized by type or treated as “best-effort” or “background” traffic. Voice packets or video-bearing packets could be classified ahead of pure Internet access traffic, depending on how critical that traffic is to users, as well as to operators of Wi-Fi infrastructure.
“There was a question, with voice merging, of how many voice calls an access point could handle in different traffic situations,” said Azimuth’s Celine. “If enterprises deploy voice, and if service providers want to offer a commercial service that somehow involved voice in a Wi-Fi environment, they will need some assurances before they do that.”
The first round of WMM certifications coincided with related capabilities being announced by several vendors. Proxim introduced its Orinoco Smart Wireless Suite and Version 2.5 of its access point software, which included support for the 802.11e QOS standard. The vendor plans to include 802.11e support in all of its new access point products from now on, Lucas said.
“All indoor and outdoor Wi-Fi products will need quality of service,” she said.
The WMM certification also is intended to spark development of a new generation of devices that previously have not been enabled for Wi-Fi. WMM can give developers of various multimedia consumer electronics products — such as PDAs, computer printers, DVD players and TVs — a heads up to help them incorporate Wi-Fi-friendly features into their products. For example, a WMM-enabled TV would offer some assurance of service quality for transferring or downloading movies from other sources.
Last month, Atheros forged an agreement with Digital 5, a home content distribution developer, under which Digital 5 will develop QOS capabilities for Wi-Fi-enabled DVD players and other devices by incorporating the 802.11e-compliant reference design from Atheros.
“Companies will be building to our designs soon,” said Sheung Li, product line manager for Atheros. “WMM drew a line in the sand that declared the basis for determining quality of service support.”
Azimuth recently added 802.11e certification testing capabilities to its W-Series Wi-Fi testing platform through a partnership with the University of New Hampshire InterOperability Laboratory (UNH-IOL). The telecommunications industry has long counted on testing specifications developed by this independent lab, and the UNH-IOL test conformance suite for Wi-Fi QOS is based directly on the Wi-Fi Alliance WMM specification.
Azimuth’s W-Series validates media access control layer conformance primarily in pre-deployment phases for suppliers of Wi-Fi chipsets and manufacturers of various types of Wi-Fi equipment. Adding the UNH-IOL conformance suite gives the test vendors both a new access point test offering and a new client device test offering, said Azimuth’s Celine.
“There are three levels of testing that are part of conformance validation,” Celine said. “The first is protocol compliance. Is the equipment doing what the standard says it should be doing? The second test phase is interoperability. There will always be some gray areas in a standard regarding interoperability, and this is where we see how the equipment conforms to WMM. Performance testing is the third phase and the one that’s most apparent to users. Quality of services doesn’t really become an issue for users until you have a problem, until you have some kind of congestion.”
The Azimuth platform already is being used for conformance tests for the earliest generation of Wi-Fi-enabled voice handsets, as well as PDAs, networked printers, DVD players and TVs, Celine said.
“If you’re streaming from a DVD player to a TV, you want to make sure the picture and the sound are consistently there,” he said. “It’s a serious application, where quality is important.”
However, the challenge with consumer electronics equipment such as DVD players, TVs and printers is that they have very little memory, which is why some form of benchmark testing is required.
Still, it is fair to say the 802.11e and WMM might have the most near-term impact on voice applications because voice over Wi-Fi is already at least a modest commercial reality.
“[Azimuth’s platform] emulates the network on a benchtop to make sure that quality of service is really working,” Celine said. “You can turn on quality of service, but does it really work, and does it really prioritize the traffic properly? And what is happening during rate adaptation? Service providers will need to be able to answer these questions if they want to promise a particular class of service.”
While Proxim’s Lucas is primarily concerned with 802.11e’s implications for the enterprise market, Celine said Azimuth expects to see a great need in the near term for Wi-Fi QOS testing from service providers that operate or resell service from public Wi-Fi hot spots.
“Their networks are finite, and they need quality of service to be predictable,” he said.
Though equipment vendors and their benchmarking needs are the primary customer target for Azimuth, the test platform vendor is hoping the W-Series becomes an important element inside carrier labs as well.
“An enterprise probably is not going to want to take this and do their own testing, though that is what they would count on their vendors to provide,” Celine said. “A carrier would have a place for this.”
However, WMM, and more generally, 802.11e, might also have significant implications for the traditional telephone companies that are increasingly looking to offer some combination of wireless and Wi-Fi service as part of their bundled triple-play service packages. Providing QOS support for delay-sensitive traffic such as voice and video could help these carriers feel more confident about relying on Wi-Fi as an access medium.
“They will need to validate this element of their triple services just like anything else,” Celine said.
“The takeaway for service providers is that there is definite movement to voice over Wi-Fi, and [the 802.11e standard] will increase it,” said Carl Blume, director of product marketing for Colubris Networks, a company that provides Wi-Fi-enabled routers for the enterprise and service provider markets. “We think carriers are starting to pick up on the fact that corporations are becoming increasingly comfortable with voice over Wi-Fi.”
Colubris recently announced new software, Service Aware QOS for Wi-Fi, that applies WMM to enterprise deployments. The software allows enterprises or the carriers managing their LANs to prioritize service traffic based on service set identifier, or SSID, to any device. The City of Malden, Mass., one of the vendor’s customers, has a municipal Wi-Fi backbone that supports data, video and voice services, and the new software will allow prioritization of the city’s emergency services traffic.
Holtz, of Zeros and Ones, said that product and service companies must work together to ensure that 802.11e gets a smooth transition from standards development to the market, something which other standards, even previous 802.11 standards, didn’t always have going for them.
Zeros and Ones’ Thundercloud product and service initiative will leverage a wireless videoconferencing solution it recently acquired from RocketStream, and QOS will be important to the application’s acceptance.
“The quality of service protection provided in the standard is one of the things that will be very important to the success of broadband wireless,” Holtz said. “One of the genesis sparks for Thundercloud is that while it is wonderful to see all of these different standards advancing, the confusion that results can have a slightly reverse effect on the adoption of new technologies by the general public. We would like for the various standards to blend into the background and for applications to be introduced in a more transparent way.”
802.11e Details:
Quality of service parameters in wireless LAN applications sensitive to latency, such as voice. Will provide for classes of service for voice and other application types through the use of traffic prioritization schemes. Also addresses battery life consumption and power management for multimedia Wi-Fi devices.
Types of devices that could be affected by 802.11e
Laptop PCs
Mobile phones
Cordless home phones
TVs
DVD players (both in-home and portable)
MP3 players
ON THE WEB
Sheung Li, product line manager for Atheros Communications, explains how the availability of more Wi-Fi spectrum will complement the pursuit of QoS standards.
WWW.WIRELESSREVIEW.COM
