Rice University claims multiuser MIMO breakthrough for TV white space

Researchers from the wireless network group at Rice University have crafted a multiuser MIMO transmission scheme for TV white- space (TVWS) spectrum in the UHF band.

"The holy grail of wireless communications is to go both fast and far," said lead researcher Edward Knightly, professor and chair of Rice's Department of Electrical and Computer Engineering. "UHF can travel far, but it hasn't had the high capacity of Wi-Fi. This [new approach] provides the best of both worlds," he said.

"When comparing UHF and Wi-Fi, there's usually a tradeoff of capacity for range or vice versa," said Rice graduate student Narendra Anand, lead author of a study on the new approach.

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From left, the Rice Wireless Network Group's Edward Knightly, Narendra Anand and Ryan Guerra. (Photo credit: Jeff Fitlow/Rice University)

Anand said the problem can be addressed via multiuser MIMO, which uses multiple antennas to boost data rates and which, in the multiuser scenario, serves multiple users over the same channel simultaneously.

Knightly, Anand and Rice graduate student Ryan Guerra designed the open-source UHF multiuser MIMO test system, which was based on Rice's "wireless open-access research platform," or WARP. The test system enabled a side-by-side comparison of multiuser MIMO for UHF and for both 2.4 GHz and 5.8 GHz Wi-Fi.

"Based on over-the-air experiments in a range of indoor and outdoor operating environments, we found that UHF-band multiuser MIMO compared favorably and produced high spectral efficiency as well as low-overhead wireless access," Knightly said.

Rice's research was supported by the National Science Foundation and Cisco Systems.

TV white-space spectrum was made available as part of the digital dividend during the switch from analog to digital TV. Supporters aim to use the unlicensed spectrum, which sits on vacant frequencies between broadcast TV channels, for wireless broadband and machine-to-machine (M2M) services in unserved areas in both developed as well as developing markets. Rice began dabbling in TVWS back in 2011, when it offered a prototype in-home white-space hotspot to Houston locals and graduate students involved in a trial of the spectrum.

For more:
- see this Rice University release

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