802.11n Wi-Fi Making a Huge Impact

Shipments of 802.11n access points have accelerated since the IEEE standard was formally approved one year ago. But what the numbers alone don't show is the new reality of Wi-Fi networks: they are fast becoming the preferred way to connect and stay connected in the enterprise.

Check our 2010 edition of the "Burning Questions for Wireless & Mobile" 

And that reality is sparking new demand from enterprise customers, and new innovation from wireless LAN vendors, to make Wi-Fi networks "work" like wired Ethernet – reliably, consistently, securely – for all kinds of traffic, including video.

"Enterprise wireless LAN vendors are continuing to work on spectrum management and other features for 2011 to create a self-adapting, self-healing wireless LAN," says Paul DeBeasi, vice president, research director, with Gartner's network and telecom strategies group. "The idea is a wireless network that will function like a wired network in terms of performance and reliability."

802.11n Wi-Fi essentials for enterprise IT

Ground zero for the 11n revolution is the college campus, with hospitals not far behind. Colleges and universities have a growing population of the unplugged: students who've never used an Ethernet cable. They have the expectation that whatever device they have will be able to connect wirelessly, and handle games, YouTube videos and "American Idol", all in addition to classroom applications.

What's more, says Jeffrey Sessler, director, information technology at Scripps College, Claremont, Calif., is that each student often now has "multiple Wi-Fi-enabled devices needing regular access." One student can have a game console, smartphone or Skype phone, laptop or tablet (or even both), printer, and Internet radio/alarm clock. (See "How can enterprise WLANs manage the bandwidth crush from mobile devices and multimedia apps?")

These changes are driving Sessler and other IT managers to design enterprise WLANs as mission-critical, production networks that are optimized for capacity and performance.

The numbers

According to IDC, the most recent WLAN quarterly revenues and shipments show the market dynamics even in the face of a global and U.S. recession (see chart).

Over the last four quarters, through June 2010, shipments of enterprise-class 11abg access points in North America have fallen to 212,500 units from 288,000. During that same period, 11n shipments, hampered by the economy initially dropped from 190,00 in the third quarter of 2009 to a low of 167,300 in the fourth quarter, before rising in the second quarter of 2010 to 250,400. The fourth quarter marked the first quarter where 11n shipments topped 11abg, and by nearly 40,000 units.

Last year, vendors shipped 520,400 11n access points in North America. In the first half of 2010, they've already shipped 422,300.

"It's penetrating very fast, and eroding 11g [sales] faster than expected," says Edgar Figureroa, CEO of the Wi-Fi Alliance (WFA), an industry group that certifies product interoperability under the "Wi-Fi" brand. The penetration is sped by the uptake of 11n in a wide range of consumer devices, including consumer electronics such as digital cameras and flat-panel TVs. The WFA has certified 1,696 devices for 11n, including 80 handsets.

According to IDC, the top five enterprise 11n vendors by shipments and revenues so far in 2010 are in order Cisco, Aruba, Meru, Motorola, and HP.

802.11n on campus

Many of those 11n access points are getting plugged in on colleges and universities. And it's here that the network transformation is most visible.

Back-to-school IT projects reshape campus life 

The campus 11n upgrade often coincides with a kind of mental upgrade in IT thinking: more IT departments now expect, and encourage, students to treat 11n Wi-Fi as their primary network connection.

Use of wired ports has plummeted on campuses, after more than a decade of costly wiring to bring a port to every pillow. Carnegie Mellon University, in Pittsburgh, this year has deactivated wired ports in all dorm rooms. Students can get a wired port just by requesting activation, but the change in policy is striking: the wireless edge is now reality.

In building rehab projects and in new buildings, fewer wired ports and switches are being deployed, yielding capital, licensing, maintenance and operational savings. "The question is how to realize the benefits of our 11n investment, and appropriately size the wired network," says Dan McCarriar, director, Network and Production Services at Carnegie Mellon.

Brandeis University in Waltham, Mass., recently renovated four dorms, offering only 11n wireless connectivity for students. "We've seen an abandonment of the wired infrastructure" by users, says John Turner, Brandeis' director of networks and systems. The estimated cost for rewiring the four buildings was $200,000. The final cost of the Aruba Networks WLAN deployment for the four buildings? Less than $80,000.

The 11n upgrade is often accompanied by upgrading 100Mbps Ethernet to 1Gbps to backhaul Wi-Fi traffic to the core network, often with Power-over-Ethernet (PoE) to simplify access point installment.

The University of Washington in Seattle is upgrading its Aruba 11abg network to 11n, planning to actively make use of the 5GHz band, with more channels and less crowded spectrum, for the first time. "We upgrade the wired infrastructure with Gigabit Ethernet switches where practical, though we expect that users will see a performance boost [even] on the older 100Mbps switches," says David Morton, director of mobile communications strategies.

At Scripps College, 60% of the Wi-Fi clients are using the all-Cisco 11n network: 17% on 5GHz, 43% on 2.4GHz, according to IT Director Jeffrey Sessler. Actual throughput for a given end user depends on a host of variables, including the 11n client radio, number of clients linked to a given access point and the various applications in use. But Sessler says an Apple iMac, right out of the box, can sustain 130M to 140Mbps when close to an access point that uses the 5GHz band and is configured for the wider 40MHz channels.

At Scripps, as with many other 11n deployments, the network design is focused on capacity, not coverage. "We try to shoot for no more than 12 to 15 clients per access point," Sessler says. "With dual radios [one on 2.4GHz, the other on 5GHz], this ensures that most access points are lightly loaded and able to meet the most demanding of clients."

While increased throughput is one benefit of 11n, there are others, equally important. One big difference from 11abg is "improved client reliability, especially in the fringe or RF-challenged areas," Sessler says.

But 11n can bring unexpected challenges. Abilene Christian University in Abilene, Texas began phasing in its 11n WLAN upgrade to support the new iPhone 4, the first model to feature an 11n radio, but only on the 2.4GHz band. ACU is almost unique: each incoming freshman gets the latest iPhone (or iPod touch) and they're used extensively in classrooms as part of a university-wide mobile learning project. But a carefully configured 11n WLAN in a big lecture hall became unstable with a mixed load of 11n and legacy wireless clients. For now, ACU has shut off 11n in the hall, so the iPhones run as 11g clients, until the IT group can sort out what's wrong.

Ethernet-like Wi-Fi?

Achieving Ethernet-like Wi-Fi with 11n requires planning and investment. "To get the full benefit of 11n, it has to be optimized as part of a well-designed WLAN architecture," says Andrew Borg, senior research analyst in the Wireless & Mobility Practice at Aberdeen Group.

That can be a challenge today. "We are looking for improved tools and management systems," says UW's David Morton. "The current tools, at least how we utilize them, provide some basic information. But I'd love to see better ways to proactively and automatically spot and deal with trouble."

Vendors are focusing attention on making Wi-Fi more deterministic, more resilient and more managed. Earlier this year, Aruba, Cisco and Ruckus Wireless all announced software changes, via beam forming, to better support multi-cast video over 11n. The results can be dramatic, as this review by Craig Mathias of the Ruckus 7300 series access points shows. 

Transmit beam forming is just one of the optional features in the 802.11n standard that vendors are now racing to deploy. Together, they can dramatically improve the Wi-Fi experience. One example is a technique called space-time block coding, which exploits 11n's multiple antennas more for improved signal reliability than for higher data rates. Users will see more consistent data rates, without fading or dropping.

Pending amendments to the 11n standard will add key new features also: 802.11v will add an array of counters for statistics gathering, add power management to improve battery life and improve support for location data. The 11k radio resource management standard packs more intelligence into the client radio, to cooperate with the access points to improve signal quality.

The Wi-Fi vendors had already been implementing a slew of proprietary features to address this challenge. They all involve extending control and intelligence to the Wi-Fi client, and coordinating its requirements, behavior and activities with the Wi-Fi access point infrastructure. Aruba's 2.0 release of its Adaptive Radio Management technology is one example.

Meraki, which like Aerohive uses an architecture that eliminates separate WLAN controllers, recently introduced its Traffic Shaper, a feature that applies traffic control policies based on deep-packet inspection, and Auto RF, for spectral-analysis and optimized radio configuration.

The Wi-Fi Alliance's Wi-Fi Multimedia Admission Control specification, currently in development, will let wireless networks negotiate and manage streaming media sessions, so a request for a high-definition video doesn't choke off Wi-Fi voice users on the same access point. (See "What's next for Wi-Fi?")

Such innovations, spurred by the 11n ratification, are moving us toward a wireless environment that's not just "everywhere" but everywhere reliable, consistent and adaptable.

John Cox covers wireless networking and mobile computing for Network World.

Twitter: http://twitter.com/johnwcoxnww

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