Networking & Wireless

Should You Upgrade to 802.11ac?

The latest WiFi specification promises speed and capacity advantages, but the performance it delivers will depend on your district's devices and infrastructure.

802.11ac wifi in the classroom 

As districts upgrade or expand their wireless networking infrastructure to support 1-to-1, online assessments and other digital learning initiatives, many are future-proofing their investment by moving to 802.11ac technology, the latest WiFi specification.

White Bear Lake Area Schools (MN) is one of those districts. According to director of technology Mark Garrison, the district had a total of about 200 access points and needed approximately 750 to support its new 1-to-1 initiative. Adding more than 500 new APs to the existing network would have cost as much as replacing the entire wireless infrastructure, so they went the replacement route with Extreme Networks. They started implementing the new system last summer and planned to complete it in March.

Garrison said, "We could have kept with 802.11n, and that would have been fine, but we want this infrastructure to last five to eight years. We have to think about how much more data students will be pushing through there, and this certainly seemed like [the] way to go." Part of Garrison's planning was based on the lifecycle of today's mobile devices. "We need that infrastructure to last through three generations of [client] devices, so we try to think in terms of infrastructure that will be compatible with those devices. If schools can afford it, they should go with the up-and-coming standard because it's going to serve them better in the long run."

Helping Older Devices Run Better
While 802.11ac-compatible laptops, tablets, smartphones and other devices are becoming more commonly available on the market, 802.11n devices are still prevalent in schools. Quakertown Community School District (PA) has had districtwide wireless infrastructure for six or seven years but recently replaced its entire wireless setup with 802.11ac technology from Aruba Networks. According to director of technology Joe Kuzo, the existing equipment was due to be refreshed, and, like White Bear Lake, Quakertown made the decision to make the jump to 802.11ac. Although a few of the newer laptops in the district office support the 802.11ac standard, Kuzo said, most devices in the district still use 802.11n — but even those devices have seen some benefit from the new network.

"I won't say it's drastic by any means," said Kuzo, "but in our high-concentration areas we get slightly better connections even on an 802.11n client. As we start transitioning equipment over to supported 802.11ac cards, that's when we're really going to see more noticeable change."

Erik Heinrich, the former director of IT for San Francisco Unified School District, oversaw that district's 802.11ac implementation. Since then he has moved on to a new role as SLED (state and local government and education) engagement manager for Ruckus Wireless. According to Heinrich, 802.11n devices may experience a performance boost when connected to 802.11ac infrastructure because the "newer access points that support the 802.11ac standard are built with newer engineering, and the faster processors improve the performance for older clients because it's processing the data more quickly," he said. "So even for the older 802.11n devices, they're seeing better range and performance, even if they're not leveraging 802.11ac protocol. It's just better hardware inside the access point."

Speed and Capacity Benefits
Districts that have upgraded to 802.11ac infrastructure, particularly those that have at least some 802.11ac-capable devices, have reported increases in both speed and capacity. Pulaski County Special School District in Little Rock, AR, recently expanded its wireless network to include a mix of 802.11n and 802.11ac access points from Aerohive. Director of IT Jimmy Hogg explained that the district has an iPad initiative, and four of its schools currently have iPad Air tablets, which use the 802.11n protocol. The district plans to add 6,000 more devices this summer and another 8,000 the following year. Those devices will be 802.11ac-capable iPad Air 2s, which Hogg said will allow the district to reap the full benefits of 802.11ac. The newer standard, said Hogg, is "capable of giving them a lot more bandwidth per AP than we currently have."

That bandwidth increase will let teachers and students use their iPads to stream more content and participate in the Partnership for Assessment of Readiness for College and Careers (PARCC) online assessments. According to Will Reid, the district's chief technology officer, "What we're looking at is more bandwidth to each iPad, more speed to each iPad, which gives the student unlimited possibilities as far as the apps they use and online tools they access."

Is the Next WiFi Wave Worth the Wait?
802.11ac technology has been divided into two phases, called waves. Most, if not all, currently available 802.11ac networking equipment is Wave 1, with Wave 2 expected to arrive some time this year. According to Heinrich, 802.11ac Wave 2 will bring with it additional benefits, but some of them may not be worth the wait for districts considering an immediate upgrade to 802.11ac.

While the 802.11n standard provided 40 MHz channels and 802.11ac Wave 1 added 80 MHz channels, Wave 2 will add the 160 MHz channel for increased throughput. "As you get into these higher channels, the challenge is that they're only available when there isn't a lot of interference," said Heinrich. "But the most significant reason to not use 160 MHz channelization is channel reuse. Unless every wall has 30 dB of loss (concrete) it won't have any advantage over 80 MHz. 160 MHz was designed for a home streaming environment, not enterprise WLANs."

Another feature of Wave 2 is multi-user multiple input, multiple output (MU-MIMO], which Heinrich described as "the ability for multiple client devices to receive multiple streams at the same time rather than each receiving a single stream" as they do in Wave 1 networks. "The caveat to this multi-user MIMO," added Heinrich, "is that the chips for the client devices, like your iPads, your Chromebooks and your smartphones are mostly scheduled for release in volume in 2016, with few being available in 2015."

While Wave 1 can support up to three spatial streams, Wave 2 will be able to handle up to four streams to provide increased performance. According to Heinrich, additional streams require more energy, but the radios require less transmission time because they are operating at faster speeds. "Four spatial streams will really show its value with mesh, 4x4:4 laptops and MU-MIMO," he said. "However, the gains of 4x4:4 on the network are not double of what you'd get with a 2x2:2 access point because there are fewer 4x4:4 clients, and MU-MIMO isn't nearly as efficient as spatial multiplexing."

Finally, Wave 2 will have a theoretical throughput of around 1.7 Gbps, "but the access point is still connected to your wired network at 1 Gbps, so some might argue that the cabling can become a bottleneck," said Heinrich. "The reality is that it will be so unlikely that a 4x4:4:4 access point will actually, in real life, exceed full duplex 1 Gbps that it isn't worth the effort of adding cabling just in case the magic happens."

So Should You Upgrade?
For districts considering a wireless infrastructure upgrade, 802.11ac is the way to go, whether it's Wave 1 or Wave 2 hardware. "If you're in a position to do a wireless refresh, I think it would be unwise to not go with 802.11ac, and then just purchase clients accordingly," said Quakertown's Kuzo. "But if you just recently acquired a wireless infrastructure, I wouldn't look to spend additional money to get to 802.11ac."

Pulaski County's Reid also recommends 802.11ac. "If you're spending all of the money on upgrading wireless infrastructure, you probably need to go to 802.11ac," he said. "We're in an era where bandwidth is the name of the game. The more bandwidth you have, the more you can access, the more Web tools you can access, the more content you can access, the more content you can stream."

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