With distributed antenna systems, a smarter way to install wireless indoors

A premier Chicago hotel's novel approach to Wi-Fi installation uses the HVAC system to spread a wireless signal within skyscrapers.
Written by Andrew Nusca, Contributor on

In a hotel, there are an awful lot of floors, furniture and infrastructure that can make uniformly providing Wi-Fi Internet access a real headache.

Chicago'sTrump International Hotel and Tower has a novel approach. Using special wireless technology that integrates with the building's existing HVAC system, the hotel slashed costs and installation time.

All it took was a little strategy and the concept of using the hotel's HVAC ducts as a connectivity superhighway.

Not bad for 92 floors and 1.8 million sq. ft. of space.

Called distributed antenna systems, or DAS, the technology involves placing small antennas in the HVAC system and deploying a radio frequency, or RF, signal from a centralized location, passing it along the ducts throughout the hotel.

"Most people don't think about it, but most people have an expectation that they're going to get coverage everywhere," said Jon Davis, vice president for business development of indoor networks at ExteNet Systems, the company behind the deployment at Trump and McCormick Place, the city's enormous convention center. "We leverage the existing heating and ventiliation to propogate RF.

"We locate an RF source in strategic areas in the ductwork and treat it as a wave guide. The RF source rides along metal duct work. It's called the 'skin effect.' "

It takes 60 days for ExteNet to install the system in a hotel the size of the Trump, versus months using a conventional system. One advantage: no unsightly routers or wires on hotel walls, and far fewer dead spots than using a localized approach.

"HVAC really reaches all corners of the building and gives you ubiquitous coverage," Davis said. "It has aesthetic benefits, too, since everything's deployed in the ductwork and back office."

"It's also cheaper, because you're not running cables everywhere. If you're in a working hotel, it's non disruptive. We can operate in the ductwork whether it's running or not."

The reason HVAC is suitable for such a deployment because it conventionally works in a hub-and-spoke arrangement, Davis said. The vendor simply puts an RF source into the centrally located "hub" and the spokes do the rest.

Hotels aren't the only businesses that can benefit from such an approach. Hospitals and other healthcare providers, colleges and universities and virtually any high-rise building are good settings for the system.

"Where it can work, it works extremely well," Davis said. "Pre-1970 or pre-1965 [buildings], it's not a silver bullet. There are instances where we deploy hybrid systems."

And what about buildings that are close together? Davis said the RD signal can be isolated to prevent excessive signal bleeding to other properties.

"There's a real need for seamless connectivity. Mobile to mobile, machine to machine," Davis said. "You've got much more demand on the network. You need to get closer to the user to be able to accommodate the data rates that users want."

This post was originally published on Smartplanet.com

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