A test network of 100 Apple iPads successfully ran a battery of classroom multimedia applications over an 802.11n Wi-Fi network, according to Aruba Networks and the University of Ottawa, where the test was held in May.
In the test, the 100 tablets simultaneously ran one application. In all, six applications were tested, most of them specific to classrooms, and all but one of them with video content. The test showed each iPad sustaining about 1Mbps throughput for the streaming multimedia content, with no noticeable jitter, delay or frame loss.
That may not seem impressive compared to the total throughput available on a 3x3 MIMO 802.11n access point. But it was an eye-opener for university IT managers, who concluded that a properly configured 11n Wi-Fi network was capable of supporting new interactive teaching methods organized around mobile devices and multimedia, and doing so for large groups of students at the same time.
"These new devices and usage are now feasible on wireless," says Sylvain Chalut, CIO for the University of Ottawa in Ontario, Canada. "We were concerned about whether the network would be able to sustain large numbers of students connecting [with multimedia devices] at once."
Chalut says the test shows that 11n networks can support new computing devices, their attendant surge in multimedia traffic, and new teaching techniques that look to exploit both. "We were reassured on that," he says. "We can change the way we're teaching, using new media and interactions in our classrooms."
As at other colleges and universities, the University of Ottawa was seeing a big change in the mix of student computers: shifting from mainly laptops with some desktops to laptops and one or more personal mobile devices, such as smartphones and tablets. Increasingly, these devices now come with 802.11n radio adapters. University IT staff had requested the test to determine whether Wi-Fi networks can handle this influx, especially in classrooms with scores or hundreds of mobile clients.
Aruba is the school's Wi-Fi vendor. For the test, the company deployed four dual-radio AP-135s; its high-end 802.11n product; and an Aruba 6000 Mobility Controller running Aruba OS version 6.1, the latest release of the system software. IPv6 was enabled across the WLAN, which was set up in a 250-seat, stadium-like classroom. The network was managed by Aruba's AirWave network management application. Measurement was handled by VeriWave Wavesite.
The applications were from a handful of vendors that target the higher education market. Nearly all the apps had video content, including high-definition video. Among the applications:
+ Blackboard Mobile Learn, from Blackboard, which provides mobile device access to the vendor's learning management system;
+ Apple Facetime, from Apple, the video conferencing application that's part of the iOS operating system for iPhones and iPads;
+ Apple AirPlay, from Apple, for automatic wireless streaming of video to an Apple TV, which was connected to the classroom's projector;
+ Furnace IP Video System, from HaiVision, for distributing local video content;
+ ResponseWare, from Turning Technologies, which allows real-time interactive responses from clients to polls and surveys.
Also part of the test was simultaneous video content streaming by all 100 tablets.
The test is essentially a showcase of various Aruba technologies. Last year, Aruba organized the launch of the Multimedia-Grade Wi-Fi Working Group, which brings together users and vendors. The group drafted a white paper, "A Blueprint For Multimedia-Grade Wi-Fi," which outlines their experience in creating or upgrading a Wi-Fi network specifically for multimedia traffic.
The Ottawa iPad network made use of Aruba's band steering implementation, so all the tablets were pushed to connect to an access point using the 5GHz band instead of 2.4GHz, according to Khalil Chamoun, network specialist with the university's computing and communications services group.
In addition, the automatic load balancing feature ensured the iPad connections were spread evenly across the four access points, so each access point typically had 24-26 connections. The network made use of another feature, application fingerprinting, to automatically give Facetime interactive video traffic higher priority over other traffic, to ensure an optimal video chat experience, Chamoun says.
The video streams in the various applications were glitch-free throughout the test, according to Chamoun.
John Cox covers wireless networking and mobile computing for Network World.
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