Electronic Design

Wi-Fi And White Space Combo Promises Better Broadband Wireless

Bringing broadband connections to underserved areas is high on the agenda for the National Broadband Plan. Wireless is going to play a major role in filling this need. For example, Wi-Fi is a good possibility as it is inexpensive and widely available while offering very high data rates.

The problem is its limited range. Data radios operating in the newly available white spaces below 700 MHz can easily solve the range restriction but lack the speed potentials of Wi-Fi. How about a combination of the two? That’s what Rice University of Houston wants to do.

Rice University researchers recently won a $1.8 million National Science Foundation (NSF) grant for one of the nation’s first real-world tests of wireless communications technology that uses a broad spectral range, including dormant broadcast television channels, to deliver free, high-speed broadband Internet service.

The five-year project calls for Rice and Houston nonprofit Technology For All (TFA) to add “white space” technology to the wide-spectrum Wi-Fi network they jointly operate in Houston’s working-class East End neighborhood.

Launched in 2004 with a grant from the NSF, the TFA Wireless network uses unlicensed frequencies ranging from 900 MHz to 5 GHz. The new grant will allow researchers to take advantage of new federal rules that open the unused TV channels between 500 MHz and 700 MHz called white spaces. The network will dynamically adapt its frequency usage to meet the coverage, capacity, and energy-efficiency demands of both the network and clients.

The new grant will pay for the development and testing of custom-built networking gear as well as smart phones, laptops, and other devices that can receive white-space signals and seamlessly switch frequencies in much the way that today’s smart phones connect to the Internet via either Wi-Fi or a cellular network. The grant will also allow Rice social scientists to conduct extensive studies in the neighborhood to find out how people interact with and use the new technology.

“Ideally, users shouldn’t have to be concerned with which part of the spectrum they’re using at a given time,” said Rice’s Edward Knightly, the principal investigator on the project. “However, the use of white space should eliminate many of the problems related to Wi-Fi ‘dead zones,’ so the overall user experience should improve.”

White space has become a hot-button issue in recent years, with Congress and the Federal Communications Commission each debating whether to auction or make freely available the broadcast frequencies that were opened up by the 2008 switch from analog to digital TV broadcasting.

As a result of the five-year NSF grant, all the information about the Rice/TFA tests—including how the equipment works, how much it costs to operate, and how citizens use it—will be freely available. That should make it easier for companies and municipalities to assess the cost of setting up and operating their own wide-spectrum networks. It may also help regulators as they compare the pros and cons of auctioning off white-space bandwidth or freeing it for unlicensed, Wi-Fi-style development.

The project marks the latest collaboration between TFA and Rice University. Led by Knightly, researchers from the Rice Networks Group teamed with TFA to build TFA Wireless in 2004. The network uses custom access points to provide free high-speed Internet to more than 4000 East End Houston residents. It also serves as a technology test bed, a place where Rice researchers can conduct real-world tests on new transmission platforms, custom-built mobile phones, in-home health-monitoring devices, and other wireless gadgets.

The equipment is expected to be a combination of white space and Wi-Fi radios that will switch seamlessly to accommodate the existing conditions. This will help users extend battery life and get an improved connection. The researchers also will explore the potential energy savings from powering down Wi-Fi nodes and covering large portions of the network with a small number of white-space transmitters during off-peak hours.

Rice University

Technology For All

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