New software being developed at the University of Michigan could help alleviate signal interference by directing wireless traffic similar to a stoplight at a roadway intersection. The software, known as GapSense, uses a universal language of energy pulses and gaps of varying lengths to convey simple warning messages between devices that don’t normally interact with one another. These “stop” or warning messages could be sent either at the start of a communication or between information packets.
“All of these devices are supposed to perform their designated functions, but they’re using the same highway and fighting for space,” Kang Shin, the Kevin and Nancy O’Connor Professor of Computer Science at the University of Michigan, said. “Since they don’t have a direct means of communicating with each other because they use different protocols, we thought, ‘How can we coordinate them so that each can perform their functions while minimizing interference with the others?’”
Researchers identified several problems to focus on. While the majority of wireless devices are equipped with the standard “carrier sense multiple access” (CSMA) protocol that directs them to confirm radio silence before sending out a transmission , some wireless technology standards take longer than others to initiate transmission. ZigBee, a low-powered specification that links networks of small radios to automate home and building systems, takes 16 times longer than Wi-Fi to initiate transmission—a delay that might signal to Wi-Fi that “the coast is clear,” when in fact, a ZigBee packet is on its way out.
“The little guy might be talking, but big guy cannot hear it,” Shin said. “So the little guy’s communication will be destroyed.”
In addition, devices transmitting on different bandwidths are unable to “hear” one another’s communications to avoid accidentally “talking” over them.
Using the GapSense software in a simulated office environment, university researchers were able to reduce a 45 percent collision rate between ZigBee and Wi-Fi to 8 percent. The software also reduced a 40 percent collision rate between wide- and narrow-bandwidth devices to almost zero.
Researchers predict GapSense could also reduce energy consumption of Wi-Fi devices by up to 44 percent by enabling the Wi-Fi receiver to operate at low clock rates when not actively receiving information packets and directing the faster-clocked transmitter to send a “wake-up message” to the receiver when an incoming packet is detected.
“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.”
For more information, visit The University of Michigan.
