Complications that the influx of Apple iPads and iPhones bring to enterprise Wi-Fi networks and wireless LAN administrators are illustrated vividly at The Ottawa Hospital in Ontario.
The hospital decided in 2010 to deploy 3,000 iPads to doctors, internists, and pharmacists in support of strategic patient care applications. All data was going to be streamed to the iPads, and the Apple tablets only communicated over Wi-Fi. "Therefore, the [wireless] network became quite important," says CIO Dale Potter. "We invested a mound of money in the network [in summer 2011]."
The hospital picked Aruba Networks to design and deploy a Wi-Fi network that currently numbers nearly 1,600 802.11n access points. "No one could answer me when I asked, 'What will happen when we scale to 3,000 iPads by year-end, and eventually to about the same number of other iOS devices?'" Potter recalls.
Aruba CEO Dominic Orr called in the Aruba Customer Engineering team, a small consulting group that handles the toughest, most baffling challenges that the vendor encounters in enterprise deployments.
Based on its experience over the past couple of years with enterprise WLANS, the team has identified a range of issues that these networks face with the surge in iOS and Android mobile devices, according to Chuck Lukaszewski, senior director of Aruba's professional services group. Currently, iPhones and iPads overall remain the most popular brands of new smartphones and tablets in the enterprise.
"We're seeing extremely rapid increases in the aggregate number of mobile devices on customer networks, across all sizes of organizations," says Lukaszewski. Especially in higher education, numbers are doubling or tripling from year to year.
The issues confronting IT groups include changes in RF design and the appropriate level of access point density; poor device roaming; and new and different loads on the WLAN's control path -- the demand for authentication services, for IP addresses, license management, multicast and broadcast traffic spikes.
RF design, density
For years, an industry rule of thumb was to deploy one access point for every 3,600 to 5,000 square feet for data networks, and every 2,500 square feet for VoIP. The Aruba team routinely now goes with the higher density for mobile device deployments.
There are two key benefits, Lukaszewski says. One is better Wi-Fi signal levels. Virtually all smartphones and tablets with 802.11n radios support only one data stream and use one antenna. As a result they cannot make use of techniques like MRC (maximal ratio combining), which can exploit multiple streams and antennas to boost the signal to noise ratio on the radio link.