Stanford researchers have developed new technology that allows wireless signals to be sent and received simultaneously on a single channel. The breakthrough could lead to faster and more efficient wireless networks.
Stanford researchers have developed new technology that allows wireless signals to be sent and received simultaneously on a single channel. The breakthrough could lead to faster and more efficient wireless networks.
Until recently radio traffic was only able to travel in one direction at a time on any given frequency. You will probably remember using the infamous ‘over” and “over and out” when using a walkie talkie as a kid?
Being able to communicate in both directions at the same time,
not surprisingly, makes it twice as fast as current technology.
"Textbooks say you can't do it," said Philip Levis, assistant professor of computer science and of electrical engineering. "The new system completely reworks our assumptions about how wireless networks can be designed," he said.
Mobile phones currently allow two way communication using a complicated work around that is expensive and needs careful planning, making it unfeasible for wireless networks like Wi-Fi.
A small group of Standford graduates began working on the project after coming up with what seemed like a fairly simple concept “What if radios could do the same thing our brains do when we listen and talk simultaneously: screen out the sound of our own voice”?
In most wireless networks, each device has to take turns speaking or listening. "It's like two people shouting messages to each other at the same time," said Levis. "If both people are shouting at the same time, neither of them will hear the other."
Over a period of several months, and with the help of professor Levis the group figured out how to build the new radio device.
The most difficult obstacle to overcome was that incoming signals tend to be overpowered by outgoing signals, preventing the device form ‘listening’ while ‘talking.
The group hypothesised that if the receiver could filter out the signal from its own transmitter then incoming signals should be easier to pick up. This works because a radio ‘knows” what it is transmitting and consequently what should be filtered out. The principle is the same as used in noise cancelling headphones.
The breakthrough is making ‘big noise’ and has already won the researchers an international award. Prior to the demonstration no-one in the field believed that it was possible. One researcher even told the trio that it wouldn’t work “something so simple could not work, if it was that obvious, someone must have tried it already”.
The implications for future networks is phenomenal, the most obvious benefit is that being able to send and receive at the same time doubles the amount of information transferred over an given time period. This would lead to faster and less congested networks in both the office and at home.
The group has a provisional patent on the technology and is working to commercialize it. They are currently trying to increase both the strength of the transmissions and the distances over which they work. These improvements are necessary before the technology is practical for use in Wi-Fi networks.
