Forget 3G, 5G is round the corner | Mana Blog... for all
Sep 18, 2011

The days of waiting for smartphones to upload video may be numbered thanks to Rice University researchers who have invented a new "full-duplex" technology allows wireless devices like phones and tablets to both "talk" and "listen" to wireless cell towers on the same frequency something that requires two frequencies today.

"Our solution requires minimal hardware, both for mobile devices and networks, which is why we've attracted the attention of every wireless company in the world," said Ashutosh Sabharwal, a professor at Rice. "I expect people may see this when carriers upgrade to 4.5G or5G in just a few years."

Sabharwal along with Achaleshwar Sahai and Gaurav Patel have set records with a signal quality at least 10 times better than any other. "We've shown that we can add full duplex as an additional mode on existing hardware. Device makers love this because real estate inside a phone is at a premium, and it means they don't have to add new hardware that only supports full duplex," Sabharwal said.

How is full-duplex possible?
To explain why full-duplex was long thought impossible for wireless networks, Sabharwal uses the analogy of two people standing far apart inside an otherwise empty arena. If each shouts to the other at the same time, neither can hear what the other is saying.

The easy solution is to have only one person speak at a time, and that's what happens on two-way radios where only one person may speak at a given time. Phones achieve two-way speech 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 the only other sound in the arena - the person shouting from far away.

"We use antenna tech called MIMO, which are common in today's devices," Sabharwal said. "MIMO stands for 'multiple-input multiple-output' and it uses several antennas to improve overall performance. We took advantage of the multiple antennas for our scheme, which is the main reason why all wireless carriers are very comfortable with our tech."

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