Rice demonstrates full-duplex wireless technology

New approach could double wireless capabilities when 5G networks arrive

Rice University researchers today announced they have successfully demonstrated full-duplex wireless technology that would allow a doubling of network traffic without the need for more cell towers.

Ahutosh Sabharwal, a Rice professor of electrical and computer engineering, said the innovative full-duplex technology requires a minimal amount of new hardware for both mobile devices and networks.

However, he added that full-duplex technology does require new wireless standards, meaning it might not be available for several years as carriers move to 5G, or Fifth Generation, networks, he added.

Today, the largest national carriers in the U.S., AT&T and Verizon Wireless, are in the early stages of rolling 4G networks on LTE (Long Term Evolution) technology, while Sprint has a more fully developed 4G network running over WiMax.

Full-duplex technology would allow a cell phone or other wireless device to transmit data and receive data on the same frequency; today's networks require separate frequencies to send and receive.

In effect, therefore, full-duplex technology could double a network's capacity.

Rice reported that its innovation has attracted interest from wireless companies globally, noting that carriers are universally concerned about having enough spectrum to support the continuing explosion of wireless devices and their increasingly complex applications, such as video.

One of AT&T's arguments in wanting to purchase T-Mobile USA for $39 billion is to gain access to more wireless spectrum.

Asked on Tuesday to comment on the full-duplex technology demonstrated at Rice, an AT&T spokesman said the carrier would need to study the innovation before commenting on it.

Sabharwal and his colleagues, Melissa Duarte and Chris Dick, first wrote in 2010 that full-duplex was possible, and this summer Sabharwal and other colleagues showed a full-duplex signal with 10 times better reliability and throughput than any other touted by researchers, Rice officials said.

Sabharwal said Rice has also been able to show it can add full-duplex as an additional mode to existing hardware, such as smartphones, where space is limited. That means that a smartphone maker would not need to add new hardware to support full-duplex.

Rice's new technology was able to repurpose MIMO (Multiple Input, Multiple Output) antenna technology, which is already fairly widely used.

MIMO uses multiple antennas and the Rice team was able to send two signals in a way that they cancel each other out, allowing a clear signal to go through over the single frequency.

Cancellation of signals had been proposed in theory for full duplex networks a while ago, Sabharwal said, but it took time to figure out a way to implement the idea at low cost without sophisticated new hardware.

In addition to full-duplex technology, Rice has created a Wireless Open-Access Research Platform (WARP) with open source software that provides a space for researches from other organizations to innovate freely and examine full-duplex innovations.

Also, Sabharwal's team has demonstrated it can provide full-duplex in asynchronous mode, which means that one wireless node can start receiving a signal at the same time it is transmitting, instead of waiting to finish the transmission.

Sabharwal and colleagues have also published their theory on how full-duplex wireless networks work. The authors say the document can be used by engineers interested in adopting the technology.

Matt Hamblen covers mobile and wireless, smartphones and other handhelds, and wireless networking for Computerworld. Follow Matt on Twitter at @matthamblen, or subscribe to Matt's RSS feed . His e-mail address is mhamblen@computerworld.com.

Copyright © 2011 IDG Communications, Inc.

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