5G Wireless Research Nears Breakthrough

A new technology that allows devices to send and receive data at the same time could debut in a few years as the foundation for future 5G networks, its developers say.

Currently in development at Houston's Rice University, the "full duplex" wireless technology would allow wireless devices such as cell phones and tablets to both "talk" and "listen" to wireless cell towers on the same frequency — something not possible with today's 3G and 4G technology.

"Our solution requires minimal new hardware, both for mobile devices and for networks, which is why we've attracted the attention of just about every wireless company in the world," said Ashutosh Sabharwal, a professor of electrical and computer engineering at Rice.

"I expect people may start seeing this when carriers upgrade to 4.5G or 5G networks in just a few years."

Sabharwal and his team have been developing full duplex transmission since 2010, and this summer the group set new performance records with a real-time demo of the technology that produced signal quality at least 10 times better than any past results.

Full duplex technology could easily be implemented into current devices by tweaking current hardware.

"Device makers love this because real estate inside mobile devices is at a premium," Sabharwal said.

Full duplex wireless was long thought impossible, Sabharwal said. To understand why, imagine two people standing far apart inside an otherwise empty arena. If both people shouted at the same time, neither would hear what the other was saying.

The easy solution is to have only one person speak at a time, and that's what happens on two-way radios. Cellphones achieve two-way communication by using two different frequencies to send and listen.

Rice's team overcame the full duplex hurdle by employing an extra antenna and some computing tricks. In the shouting analogy, the result is that the shouter cannot hear himself, and therefore hears only the other person.

"We send two signals such that they cancel each other at the receiving antenna — the device ears," Sabharwal said. "The canceling effect is purely local, so the other node can still hear what we're sending."

Sabharwal says his team is already working on the next phase of the technology, called asynchronous full duplex — that is, one wireless node can start receiving a signal while it's transmitting.

Asynchronous transmission would be important for carriers wishing to maximize traffic on their networks.