April 11, 2013
GapSense To Help Competing Wireless Protocols Play Nicely Together
Enid Burns for redOrbit.com — Your Universe Online
The wireless space is getting crowded. Wi-Fi signals, Bluetooth devices, ZigBee sensor nodes and other electronics and protocols claiming space in the air are causing dropped calls, wasted bandwidth and bad connections. We've noticed.The situation is likely to get worse as more devices use various wireless protocols. Software developers at the University of Michigan in Ann Arbor are trying to alleviate that problem. They're developing GapSense, a piece of software that lets devices using different protocols -- such as Wi-Fi, Bluetooth or 3G -- send stop and warning signals to each other.
These wireless connections aren't able to communicate. Therefore a Wi-Fi signal that goes up against a Bluetooth signal may cause interference that gets in the way of a clean connection, clear voice call or fast wireless stream. This software helps those incompatible signals deal with each other and go about their business. GapSense creates a common language of energy pulses and gaps. Devices using this software could be programmed to send a stop or warning message when it begins a transmission, or in between packets. This signal can alert other gadgets or devices in the area to an action, so they don't try to interfere.
"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 the University of Michigan, in a statement released by the university. "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 others?'"
GapSense has been found to reduce interference by more than 88 percent on some networks with a diverse range of devices, the researchers found.
CTIA counted more than 321 million Wi-Fi-enabled cell phones, laptops and tablets in the United States in 2013. "That's more than one device per person, and it's just the items that use Wi-Fi, the protocol that transmits big chunks of data over relatively long distances," the statement said. Several of those devices also have a 3G or 4G wireless signal, Bluetooth, or other wireless protocol capabilities as well. Then there's the devices that work with those laptops, tablets and smartphones.
Bluetooth and ZigBee use the same wireless spectrum as Wi-Fi, "but they all speak different languages," the report says. Bluetooth is a short-range network that can connect headsets, keyboards and other devices to smartphones, computers and cars. ZigBee is a low powered signal typically used by sensors. It links small radios to automate home and building systems, such as lighting, security alarms and thermostats. It is also used commonly in hospitals to gather medical data from patients.
"All these devices are already equipped with the standard 'carrier sense multiple access,' or CSMA protocol that programs them to listen for radio silence before they send their own transmissions. But often it doesn't work," the release said.
The GapSense software will make those periods of listening and sending messages stronger, and in a common language so they can maintain their connections.
Researchers observed ZigBee takes 16 times longer than Wi-Fi to gear up from its idle state to transmit information. This might give Wi-Fi the wrong impression that a ZigBee packet is on its way out.
"The little guy might be talking, but the big guy cannot hear it," said Shin. "So the little guy's communication will be destroyed."
Researchers tested the GapSense software in a simulated office environment. "With moderate Wi-Fi traffic, they detected a 45 percent collision rate between ZigBee and Wi-Fi, and GapSense reduced that to 8 percent," the statement said.
Findings from the development and testing of GapSense will be presented by Shin Xinyu Zhang, a former doctoral student in electrical engineering and computer science, at the IEEE International Conference on Computer Communications on April 18 in Turin, Italy.