Networking | Feature

802.11ac: Future-Proofing the Wireless Campus

Determined not to be caught off-guard by changing technology needs on campus, the University of Houston is revamping its wireless infrastructure and piloting the upcoming 802.11ac WiFi standard.

• By Dian Schaffhauser
• 09/05/13

It took 60-something tweets to Chancellor Renu Khator about the sorry state of the campus wireless network at the University of Houston for the Information Technology organization to realize that somehow it hadn't kept up with its users. "The demand changed and caught us napping," says David Johnson, executive director of technology services and support. "Any time you get that kind of response, you know it's a priority."

The twitter conversations surfaced in early 2012, shortly after Johnson had arrived at the campus. At that time, IT followed a coverage or "hotspot" model, he explains. "We could honestly say that every building on campus had WiFi." The thinking was this: Put in access points (APs), measure the footprint of the AP, "and if you're within the footprint, you have coverage." The 500-acre campus had between 1,200 and 1,500 APs serving 40,000 students. What the university found, however, was that the coverage model couldn't sustain the explosion of wireless devices being used on campus.

U Houston spent the next 18 months switching out that coverage model for a capacity model--and learned how to be proactive in the face of changing technology needs. Now the university is preparing to ramp up to the next level of wireless with a pilot to understand how to best use the next WiFi standard, 802.11ac.

From Intuition to Math
Johnson says that in the past, intuition played a major role in figuring out how WiFi coverage should be handled: "We know students are here and they need WiFi, and we're going to put up an AP." Obviously, as the pile of complaints showed, that became insufficient. So Johnson, CIO and Associate Vice Chancellor Dennis Fouty, and a team of business analysts sat down to sort out what the latest wireless needs were and how much bandwidth was required.

Their new goal was to plan wireless coverage based on a "fire code" model; in other words, accommodate wireless demand when any designated space is filled to capacity. Demand included students watching recorded lectures, using multimedia on the learning management system, doing desktop collaboration, sharing files, and watching streaming media and playing games for entertainment.

IT knew that the busiest times on its network were Tuesday and Thursday between 10 a.m. and 2 p.m. "It's the class schedule," notes Johnson. "Those are days where you have longer classes and longer breaks in between. Between 10 and 2 [students] are going to sit down and do their homework or unwind and watch a movie. It's an interesting pattern that develops, but it's consistent. We see it over and over."

That's when math overtook intuition. "We calculated that we probably needed to provide five megabits per second per student," recalls Johnson. The team also needed to make some assumptions. For example, although students have multiple wireless devices--smartphones, laptops, and tablets--they usually only use one at a time. Another assumption: Usage in an area will change, depending on how well served the users are; for instance, IT could drive students to congregate in an area for gaming by catering to higher bandwidth needs. While the mathematical model wasn't entirely "scientific," it allowed IT to calculate how many students could be supported in a particular area based on the usage in that area. Explains Johnson, "We started to look at locations where we knew we were going to have higher throughput and then we changed the math in those locations."

A Paradigm Shift
The IT team redesigned the network around 802.11n, the WiFi standard in place at the start of the project a year and a half ago. After assessing vendors, the school settled on Meru Networks and brought in a company engineer to help with the revamp.

IT also developed a set of standards by which to work, including the placement of all new APs under the ceiling, where they could be seen. "When a student is walking through, they can look up and say, 'Oh, I can get a signal here,' or 'There are no lights blinking. Maybe I should call somebody,'" Johnson says. The idea is that if a student sees an AP but still can't get a signal, he or she can call the service desk, report their exact location, and tech support can put up a ladder and switch out the AP. "It is a different way to look at the way you provide the service," he adds.

U Houston didn't have an unlimited budget to undertake a total redo of its wireless infrastructure; it had to set priorities. So IT organized all spaces by 10 categories. Category 1 was classrooms where the faculty member wanted to use wireless as part of the curriculum; category 2 was high-density study areas; category 3 was general-purpose classrooms, and so on. Academic spaces were given first priority, followed by residence halls, non-academic spaces, administrative offices, other low-density spaces, and outdoor areas, in that order.

A change in thinking also took place with the upgrade: an imperative to stay on top of the user experience. "That's part of the paradigm shift," Johnson explains. "We don't just test by looking at diagnostic tools," though IT has seriously expanded the use of such tools. "Our information technology availability center is watching WiFi 24-7, 365 days a year. When we see a change in the number of APs available, a work order immediately goes out. It's so critical. There is an all-out effort to achieve what the user is looking for: sufficient amounts of bandwidth to do what I want to do anywhere I want to do it. Strategically, that's meeting demand."

Johnson likes to tell a chicken-and-egg story about the appetite for more wireless capacity. When he first arrived on campus, he says, whenever he visited Agnes Arnold Hall, a high-use academic building, he'd find a handful of students using laptops, mostly running Microsoft Word. As part of the 11n work, the first change made was to that building. "Then as soon as we did it, all of a sudden laptops started springing up everywhere," he marvels. "As soon as we started expanding this across the rest of the campus, our laptop penetration was amazing."

Of course, it wasn't all smooth sailing. In the seven-story main library, for example, a "dramatic" number of APs were added over multiple weeks. But when that part of the new wireless network was turned on, "it didn't provide the performance we were looking for," notes Johnson. So the IT team changed the configuration again and again, trying to find just the right setup for what he describes as "an extremely dense environment with multiple floors and APs interfering with each other.

"It was quite a bit of trial and error that took place," he says. "We were working through a playbook." Eventually, the team puzzling it out came up with the right combination of settings. "Now we know. The configuration for the library requires this power level, and it requires channel striping like this, and we dedicate channels one and three to this purpose. Then we could say, 'What other spaces do we have that are like the library?' Well, our University Center Satellite is like the library, so we have the blueprint for it."

Testing Out the Future of WiFi
Currently, U Houston is just finishing the upgrade of wireless to its residence halls, that category of need midway down the priorities list. But even as IT continues work on 802.11n, it's looking down the road at how the next standard, 802.11ac, will work in the new wireless environment. As Johnson points out, "You start construction projects two years ahead of time. We need to know this technology now because the next new building going up in two years is going to have it."

As IDC reports, "The emerging... [802.11ac] standard promises increased bandwidth and improved resiliency that will benefit end users across a number of enterprise use cases," among them, education.

To prepare, the university has worked with Meru to set up an extensive pilot. The University Center Satellite building has been refitted with between 25 and 27 of Meru's new APs, to test how well 11ac will work in a high-usage setting. That particular space is ideal for this kind of testing, Johnson says. It's packed with take-out food stands, a market, a Starbucks, associated student offices, gamers, spaces for studying--"and [all those users] are accessing the network. That is the densest and most diverse place on campus with the largest cross-section of people going into that space."

Even better he adds, the building is underground. "So there's no interference from other devices. If you're in the Satellite, you're only getting a signal from the Satellite."

The testing will have a few different aspects. When classes start, the IT team will perform a daily count to track how many 11ac devices are in use, how many n devices, and so on, to monitor the speed of adoption of the new standard. Also, in order to make sure there's sufficient 11ac usage "to really test it," the university will invest in 30 11ac adapters that can be plugged into devices with a USB port.

That way, says Johnson, if "we have gamers sitting out there, I can go out and say, 'Hey, guys, try this,' and then give them those AC adapters for their computers and let them sit there and game for a couple of hours. We'll sit back and watch the throughput on the devices and monitor status, and then go back to those students and say, 'What was your experience--more latency or less? Did it give you what you're expecting? Does it give you what you need?' They're our litmus test."

Shortly, the pilot will also include testing in a "model classroom" where IT will issue 11ac-outfitted laptops to the students and the faculty in order to gauge how well the wireless network holds up in an intensive academic setting.

It may turn out that U Houston sees growth of 11ac far faster than anybody would expect. The moment the new network was turned on the first time in the Satellite, recalls Johnson, two devices popped up on the controller by which the APs are managed. "My guess is somebody went shopping for back to school," he muses.

These days "proactive" is Johnson's watchword. "My goal is not to have tweets going back and forth with the Chancellor. My goal is to catch that problem before it becomes a problem."

The Status of 802.11ac 802.11ac hasn't been fully approved yet through the IEEE Standards Association process. That's expected later this year or in early 2014. Devices that use the new "very high throughput" standard are projected to be widespread by 2015. But that doesn't mean vendors--or customers--haven't been paying attention. When Apple announced its new MacBook Air with 802.11ac WiFi, users sat up and took notice. It's a similar story with the Samsung Galaxy S4, and Meru Networks recently announced the AP832, a two-radio, three-stream wireless access point, which is expected to ship in September or October. According to a July 2013 report by IDC and made available by Meru, one benefit of 11ac is its use of the 5GHz spectrum, which alleviates "some of the congestion issues with 2.4GHz." As Richard Nedwich, director of the education business unit at Meru, explains, "Fewer devices today operate on 5 gigahertz, so you get less interference from neighboring WiFi and non-WiFi sources like microwaves, Bluetooth devices, and cell phones." Early experimentation also suggests that 11n devices will operate better on 11ac, Nedwich notes. "We're still trying to prove that out," he says, "but our initial deployments are indicating that there is at least as good if not better performance on AC, so why wouldn't I put my legacy devices on there?" Not all is settled with the new standard, as IDC also points out in its report. First, it needs to be ratified, even though the WiFi Alliance has already begun certifying products. Second, there's the potential for channel overlap in early-generation AC products. (A channel is a smaller band of WiFi signal range on which a device can transmit in order to cut down on interference from other devices sharing that same wireless spectrum.) Currently, the new standard calls for wider channels; 20MHz, 40MHz, and 80MHz are mandatory; 160MHz is optional. Some vendors, IDC states, recommend staying with 40MHz to minimize interference. Even with wrinkles to iron out, 11ac adoption is anticipated to enable institutions to address the areas with the highest concentration of users. Says Nedwich, "I expect that the digital classroom--a large lecture hall--will see the early-adoption deployments. Those are clearly pain points today."