April 18, 2008

8 Min Read
To the Nth Degree: 802.11n Supercharges Enterprise WLANs

By Tara Seals

It’s the applications, stupid.

That’s become the refrain for enterprise sales as businesses move from wanting basic connectivity to leveraging fatter and fatter pipes to support mission-critical apps. WLANs are no exception, and with the advent of 802.11n products — with five times the throughput of legacy WLAN gear — partners can go in with a wireless workplace story that’s been supercharged with unified communications, fixed-mobile convergence and video. As long as they get the technical requirements correct.

There are plenty of gear options to choose from to craft that story, too: The Wi-Fi Alliance has certified approximately 32 business-grade products as complying to the IEEE’s 802.11n draft 2.0 standard, which, in addition to supporting higher data rates, also offers Multiple Input/Multiple Output (MIMO) to improve coverage and density. The final iteration of the standard is still being tweaked, but current products will be compatible with (and software-upgradeable to) the final version, which is due sometime in 2009.

“The big value for channel partners is that 802.11n removes barriers,” explained Luc Roy, vice president of enterprise mobility at Siemens Enterprise Communications. “You can say that in the early days of 802.11a/b/g and wireless, partners had to open up customers to wireless and explain the value proposition. Now, with .11n, you have theoretical speeds of 300mbps, and most desktop laptops can support up to 100mbps. So all of the sudden we’re over the mental barrier of wondering if the WLAN has the capacity to support a large number of users and bandwidth-hungry applications. It’s a no-brainer.”

The faster speeds and better coverage also make for the ability to support true mobility on a WLAN, and that in turn becomes another driver. Also, unified communications in particular gets a boost from 802.11n. “Unified communications was considered really nice to have, but it becomes mandatory as soon as you become mobile,” Roy continued. “So now, UC is at the heart of every customer conversation we have about WLANs, because the two go hand-in-hand.”

He added that increasingly the customer opportunities include a bundle with an IP PBX, fixed-mobile convergence and unified communications. “It’s becoming more and more clear to the customer that they need to do this, so 802.11n opens doors for a few more opportunities and a bigger addressable market for channel partners.”

Video is another application driving enterprise demand for 802.11n, particularly in certain verticals. In health care, for instance,

doctors would like to download and have access to MRI images on the fly, or to stream lab results to the bedside. In the education sector, schools increase their competitive edge by offering latest and greatest broadband, while leveraging 802.11n in libraries or lecture halls to stream video.

“Some partners are actually creating innovative services,” said Roy. “If you go to a mall, for instance, instead of a Web page on plasma screens, you’ll have video downloaded to welcome you to the mall. This just allows you to think outside of the box, because bandwidth is not a constraint anymore.”

As for rollouts, some customers might question whether to deploy 802.11n now or wait for the final spec. “But because of UC and mobility, we say, go for it,” said Roy. “And UC and mobility together is what customers want. Channel partners can go in and sell the entire value proposition.”

The enterprise is very ready for 802.11n, “and we’ve seen quite a bit of interest, with lots of testing and piloting going on,” said Kelly Davis-Felner, senior marketing manager of the Wi-Fi Alliance. “Also, a lot of enterprise Wi-Fi users have aging networks, reaching their third, fourth, fifth birthdays. So, from a replacement-cycle standpoint, it’s a good time for 802.11n.”

For many businesses, a phased rollout works well if they already have a WLAN in place. “A rip and replace is OK for some customers, but most want a phased migration,” said Mike Tennefoss, head of strategic marketing at Aruba Networks, which sells 802.11n products through its channel program. “It does require upgrades to the wired infrastructure, including moving to GigE, updating the wiring closet switches, etc. [But] it allows them to do it on their own budget and schedule.”

This potentially can lead to a situation where a business might have legacy WLANs from different vendors. “A network-management system becomes important for simplifying that migration,” said Tennefoss. “You can look at two, three, four — as many systems that you have — and have a diagnostic and reporting capability.”

Tennefoss does caution that selling 802.11n requires attention to technical specifics. For example, first-generation 802.11n chipsets consume more power than their a/b/g predecessors. “This is really important as you look at retrofitting enterprises, because 802.11a/b/g uses power over Ethernet. With some products, putting in new 802.11n APs also requires a refresh of the PoE infrastructure.” In fact, some 802.11n products don’t support PoE at all, or don’t if the AP uses more than one radio. Thus, channel partners should do their homework.

Also, despite the availability of 802.11n access points, 802.11n clients — in laptops and handhelds — are still a rarity, although that should change gradually as more and more notebooks ship with the upgraded technology. “Even though 802.11n allows for a farther distance between APs to give you the same density, most of the clients out there are b/g,” said Tennefoss. “For some period of time, we’ll be living with legacy voice clients on the handset, too. So when deploying .11n APs, you’ll need to maintain same spacing between them as you would a/b/g APs, to accommodate the lower range in the clients.”

It’s also a good idea to use shorter spacing in order to gain the capacity benefits that 802.11n promises. “If you lower number of APs, you may only increase your capacity by a fraction,” said Roy. “So as a good practice, we strongly recommend that you use the same approach as a/b/g even if the n APs are more expensive. That way you get four to six times the legacy performance.”

802.11n APs do provide benefits even to those legacy clients. “Even if you have an a/b/g client base, you’ll start seeing benefits right away,” said Davis-Flener.“The 802.11n signal is more consistent, plus it can fill in coverage gaps in stairwells, lobbies and other places not easily covered before. As we have increasing mobility in the business environment

and more voice over Wi-Fi, plus ultramobile terminals, users don’t want to break that link just because they go into a hallway.”

The MIMO technology leverages the obstacles in the environment to make the signal stronger. MIMO has a two-by-two, three-by-three or four-by-four configuration, with two, three or four completely independent radios operating on the same frequency channel, with the assumption that there are multiple paths a signal can take between AP and client due to reflections in the RF environment caused by doors, walls, furniture and the like. The paths are uncorrelated, so different transmissions take different pathways, and the signals don’t bump into each other. Instead, what you get is a much more efficient, and redundant, transmission system. “The MIMO technology means the APs are capable of picking up more signals more reliably, even if those signals are weaker,” explained Tennefoss. “So you can get better performance out of a/b/g devices.”

That becomes especially important when VoIP is involved. “If you have clients only running b/g, that’s fine,” said Roy. “The value of .11n with MIMO is that voice quality becomes much better. We’ve seen the increase in quality not just by measurements, but you can actually notice it with the ear. Sometimes with a/b/g you can hear clicks, especially when roaming from one AP to another.”

Security is another aspect partners should be able to talk about fluently. “As you start migrating more and more voice and data traffic to all-wireless, chances are you’ll be encrypting that traffic via WPA2,” said Tennefoss. “So the architecture and encryption processing become limiting factors as far as all-over performance. So, you’ll need to design and test for high-performance encryption throughput.”

Understanding the different options in architecture is another requirement. “In terms of architecture, the thin AP with a controller was really winning the race,” said Roy. “But now the traffic could increase by five or six times, so you have to ask if it makes sense to bring all the traffic back to the controller. You could have a hybrid approach, where you tunnel some traffic to the controller, and also bridge some traffic locally on the AP. It will depend on a case-by-case basis.”

For instance, a company might want to tunnel voice traffic for seamless roaming. But video is a more portable application, so one could locally bridge that traffic. “You have to look at the reasons and value when it comes to architecture,” Roy said. “Are you going to dedicate a 10GigE backbone just to bring that traffic back to the controller? That’s egregious, especially in recessive times.”

Davis-Felner said 802.11n represents an industry bellwether. “It’s a turning point,” she said. “The enterprise is becoming increasingly wireless and mobile. Ands fits that trend. People will be doing a lot more and a lot more effectively over the WLAN.”

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