Researchers: Full-duplex radios could double spectral efficiency

Time-domain transmit beamforming is the key to doubling the efficiency of wireless networks, according to researchers at the Bourns College of Engineering at the University of California, Riverside.

The method enables the use of full-duplex radios, which can double the efficiency of spectrum, rather than the currently employed half-duplex radios. Full-duplex radios are not ideal in 3G networks and beyond because they suffer from interference between the transmission and receiving functions.

However, time-domain transmit beamforming enables the digital creation of a time-domain cancellation signal and couples it to the radio frequency front-end to allow the radio to hear much weaker incoming signals while transmitting strong outgoing signals at the same frequency and same time. "The new solution not only has a sound theoretical proof, but [it] also leads to a lower cost, faster and more accurate channel estimation for robust and effective cancellation," said UC Riverside.

The UC Riverside findings were outlined in a paper published online in the journal IEEE Signal Processing Letters. It was co-authored by Yingbo Hua and Ping Liang, who are both electrical engineering professors, and three of their graduate students: Yiming Ma, Ali Cagatay Cirik and Qian Gao.

"This time-domain method can be directly implemented at the circuit level," said the researchers in their paper. "Our experiment shows that the RF system theory shown in this paper is highly feasible with the current RF chip technology."

"We believe the future applications of full duplex radios are huge, ranging from cell towers, backhaul networks and wireless regional area networks to billions of handheld devices for data intensive application such as FaceTime," said Liang

The UC Riverside researchers have had discussions with several major wireless telecommunication equipment companies.

Cell towers are one of the most likely places to start implementing full-duplex radios, in large part because they are less constrained by existing standards. There are also applications in cognitive radio and spectrum-sharing scenarios, said UC Riverside.

For more:
- see this UC Riverside release
- see this IEEE paper (PDF)

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