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'GapSense' to control wireless traffic

Posted: 16 Apr 2013     Print Version  Bookmark and Share

Keywords:wireless  bandwidth  traffic  communications  carrier sense multiple access 

The growing use of wireless devices is increasingly clogging the airwaves, resulting in dropped calls, wasted bandwidth, and botched connections. Researchers at the University of Michigan have developed a collision avoidance software, called 'GapSense'. The new software works like a stoplight to control the traffic and "dramatically reduce interference."

The new software, called 'GapSense', lets wireless devices such that can't normally talk to one another exchange simple stop and warning messages so their communications collide less often. GapSense creates a common language of energy pulses and gaps. The length of the gaps conveys the stop or warning message. Devices could send them at the start of a communication, or in between information packets to let other gadgets in the vicinity know about their plans.

"All these devices are supposed to perform their designated functions but they're using the same highway and fighting for space," said Kang Shin, the Kevin and Nancy O'Connor Professor of Computer Science at U-M. "These devices don't have a direct means of communicating with each other because they use different protocols."

The researchers tested GapSense and found that it could reduce interference by more than 88 per cent on some networks with diverse devices.

Even among 2.4-GHz wireless devices that already use the carrier sense multiple access (CSMA) protocol, which listens for radio silence before transmitting, collisions are still commonplace. The problem is that with so many devices in operation, each has a different time delay between listening and transmitting. Thus despite their use of CSMA, collisions are inevitable as each delays by a different amount of time before transmitting into a previously clear channel. In fact, with just moderate WiFi traffic, the researchers estimate that 45 per cent of wireless data transmissions involve a collision. However, by switching to its GapSense method, collisions can be reduced to under 8 per cent, according to the researchers published results.

The software could also address the so-called "hidden terminal" problem. Newer WiFi standards allow for faster data rates on wider bandwidths than the standard 20 megahertz, but devices on different bandwidths can't hear one another's communications to avoid talking over them. GapSense could enable these devices on different standards to talk in turn. At moderate WiFi traffic, the researchers detected around 40 per cent collision rate between wider- and narrower-bandwidth devices and GapSense reduced it to virtually zero.

GapSense could also reduce energy consumption of WiFi devices by 44 per cent, the researchers said. "It would accomplish this by allowing the WiFi receiver to operate at low clock rates. With the software, the faster-clocked WiFi transmitter could send a wake-up message to the slower-clocked receiver in time for it to synch and catch an information packet."

"The impact of GapSense is huge in my opinion," Shin said. "It could be the Tower of Babel for the increasingly diversified world of wireless devices."

The University is pursuing patent protection for the intellectual property and is seeking commercialisation partners to help bring the technology to market.

Shin and Xinyu Zhang, a former doctoral student in electrical engineering and computer science, will present the work April 18 at the IEEE International Conference on Computer Communications in Turin, Italy.

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