Wireless Networking | Feature
Wireless to the nth Degree
Wireless access points that utilize the 802.11n standard offer superfast speeds and can simultaneously support a multitude of bandwidth-hogging devices.
It's fall 2011 and your college's Bio 101 class is filled to its 87-student capacity. More than half the students sit hunched over laptops taking notes. At everyone's feet lie backpacks containing one or two additional devices--cell phones, smartphones, iPods, iPhones, you name it--all of which require time and space on your wireless network. Now pull back and look at your entire campus. Buildings everywhere are filled with students, administrators, instructors, and myriad guests, all carrying multiple devices for which they expect wireless support. Does your network have what it takes?
It's a question that many IT administrators worry about late into the night, particularly as the number of mobile devices on campus continues to skyrocket. Fortunately, today's technology--specifically, 802.11n-capable wireless access technology--does makes it possible to equip your campus for today's intensive mobile culture.
Dean College (MA) and Utah State University both recently upgraded their wireless networks to the 802.11n standard. For Dean, upgrading its wireless capabilities was part of a complete network overhaul that included revamping the LAN connections and replacing the phone system.
"Before, as at many colleges, the infrastructure was not thought about really, so there was no planning, no development, no strategy," says Russell Prentice, director of information services at Dean. "After a while, systems were failing, mail would stop working intermittently, and networks would crash. People didn't have a good feel for the infrastructure, so quite a lot of people duplicated everything on paper."
Utah State, which started its wireless-upgrade process around four years ago, received its first shipment of 961 access points at the beginning of this year. The university's goal is to establish a wireless network that will also serve as it primary network, says Eric Hawley, chief information officer.
This means eliminating problems commonly associated with wireless networks, such as "network congestion, bandwidth latency, lack of coverage, devices that don't roam well, and the poor quality of service when you're running voice and video," explains Hawley.
Both schools have the ultimate goal of creating campuses that are almost completely wireless, with the exception of data centers and servers, which would remain wired. The 802.11n-standard access points (AP), which enable more device traffic to flow at higher speeds, are the means to that end.
With a data rate of up to 600 megabits per second, the n-standard APs achieve speeds up to six times that of their predecessors, 802.11a, b, or g, and they can support 50 to 100 client connections at once, even if those clients are using bandwidth-intensive applications that stream video or deliver voice over wireless LAN. They incorporate MIMO (multiple-input, multiple-output) antenna systems that can bounce radio waves off walls and other obstacles, and reach the desired receiving device from different paths, or spatial streams. Among other things, MIMO enables faster transmission and wireless access in places that were hard to penetrate with earlier wireless technology.
802.11n incorporates a new, third spatial stream, which Kevin Secino, global product marketing manager for mobility at HP, compares to opening a third lane on a highway.
"You get more traffic through three lanes than two," explains Secino. "You can think of this in a similar fashion. We're able to transmit more data through three streams than two." The three-stream technology is also completely compatible with one and two spatial streams, as well as a, b, and g technology.
Band steering, a common feature of most access-point devices, helps to keep traffic flowing smoothly on all three spatial streams. Band steering is the process by which an AP detects when a client device is n capable and steers that device onto the 802.11n streams so legacy devices can use the 802.11a, b, and g streams.
"Even if you have a device that supports 11n, it wants to stay on g if it can," explains Prentice. The Aruba APs installed at Dean force such devices onto n, freeing up space for other devices on the other bands. "If all the devices are trying to get to g, then it oversubscribes. This balances things out," he adds.
Network Architecture
Most access points utilizing 802.11n standards have comparable speeds and performance. As a result, when it came time to select a vendor, each college made its choice based largely on its specific situation. Dean College, for example, was replacing a legacy network that included "three different versions of wireless, none of which talked to each other," says Prentice. As a result, the school was looking primarily for stability.
"We can only change things every five years, if we're lucky," Prentice explains. "It had to be something that could be tried, tested, and be solid,"
Utah State settled on APs from Meru Networks that enable "a macro-cell, single-channel technology," Hawley says.
"Meru is really an RF [radio frequency] company, and they took a totally different engineering approach," says Hawley. Normally, access points have three channels to work with: 1, 6, and 11. Two APs operating on the same channel near each other can cause interference and quality degradation. In high-density areas where you might need more than three access points, it's tricky to architect the AP layout, and the overall effectiveness of your coverage is impacted. Meru APs are available in single or dual radio models, but its virtual-cell technology allows its APs to operate on a single channel without interference.
"We didn't think [its single-channel technology] would work," recalls Hawley, but, during a demonstration, Meru connected 500 clients to access points running on one channel in a 20- by 50-foot room and "blew density out of the water."
Hawley adds that running most of the campus on one channel makes setup easier, reduces the number of overall access points, and contributes to more stable roaming. It also enables the university to set aside a separate channel specifically for researchers without having to worry about interference.
Another feature worth considering is beamforming, which creates better coverage by optimizing the link between clients and APs. Included in many vendors' 802.11n AP technology, beamforming can reduce power usage as well as interference, enabling APs to operate at stronger signal strengths with less concern for channel overlap.
"Beamforming helps you get higher throughput for greater distances, because it's concentrating the energy toward your device, rather than sending the energy everywhere," explains Jeff Schwartz, HP's global product manager for mobility.
Beamforming enables the access points, which usually contain three transmitters, to time transmissions so packets arrive at their destination at exactly the same time. With prior technology, Schwartz says, the three radios would transmit, and traffic from one would arrive slightly before traffic from another, because they took different paths.
There can be a downside, however. Beamforming relies on a signal exchange between the access point and the receiving device, which can be less effective if a device is moving around and the signal has to be repeatedly reset.
With exponential growth in the numbers of wireless devices on campus, schools are quickly having to adjust to these more complex networking challenges, and are employing sophisticated options for managing their networks. At this point, there's no doubt that 802.11n represents the best wireless technology on the market in terms of bandwidth, speed, security, and network management. At least for now.
