Your cell phone signal could soon be getting a huge boost thanks to a relatively minor tweak, if researchers at Rice University have their way.
A team led by Rice professor of electrical and computer engineering Ashutosh Sabharwal has managed to successfully demonstrate their method of increasing wireless network throughput – the rate of successful message delivery – by 70 percent, with mostly existing mobile device and cell tower hardware.
That ultimately means wireless network providers can provide more customers with faster and smoother transmitting of all data-intensive operations – including calls, video streaming and downloading apps – without having to install expensive new cell towers.
“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,” Sabharwal said in a release. “The bigger change will be developing new wireless standards for full-duplex. I expect people may start seeing this when carriers upgrade to 4.5G or 5G networks in just a few years.”
The results of their new “full-duplex” technology, first demonstrated this summer, were submitted in a paper to the Cornell University Library and just announced on Monday by the university.
It takes advantage of the fact that some current phones and mobile devices, and likely many future ones, will be equipped with several MIMO antennas, “multiple-input and multiple-output,” which allow them to transmit and receive data – from calls to streaming videos – simultaneously.
Currently, however, MIMO devices segment the transmission and reception processes into two separate frequencies, each of them bouncing from a cell tower to the mobile device.
Using just one frequency for transmission and reception per phone would be more efficient for wireless networks, but there’s a big problem with that – incoming signals aren’t as strong as the phone’s own transmissions, causing massive interference.
As Rice explains, it’s as if two were people standing in an empty arena and trying to call out to each other at exactly the same time: they would drown each other out. Instead, they must take turns or, simultaneously transmit their messages by another means. Hence the need for two frequencies on modern phones.
But the Rice team was able to get around this problem by reprogramming the phones and using one extra antenna to send out canceling signals that cause each phone to only receive or “hear” incoming data, not the data it is sending out.
“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.”
“We took advantage of the multiple antennas for our full-duplex scheme, which is the main reason why all wireless carriers are very comfortable with our technology,” he added.
“I can say that If it worked, it would be beneficial,” said Ken Schmidt, president of Steel in the Air, a cell tower lease consultancy. “The carriers do have to use two separate frequencies- receive/transmit, which also requires either separate antennas or separate antenna units inside one panel. So if they can duplex, the carriers would be interested because they could better use the existing spectrum and could use fewer or smaller antennas.”
The tweak, while relatively simple and cheap from a technical standpoint, wasn’t conceptually very difficult: Previously, it was theorized that full-duplex would be impossible for wireless networks.
But in 2010, Sabharwal and his fellow rice researchers Melissa Duarte and Chris Dick published what Rice deems to be the “first paper showing that full-duplex was possible,” which led to their breakthrough demonstration this summer.
The Rice team also demonstrated the first working asynchronous full-duplex transmission as well – that is a mobile device that can begin transmitting at the same time it is receiving.
Their work was funded by the National Science Foundation, the Roberto Rocca Education Program and Xilinx Incorporated.
But as groundbreaking as they claim it is, it’s worth noting that there’s been heady competition when it comes to advancing full duplex.
In February, a team at Stanford University claimed to have developed the first full-duplex wireless technology. They’ve applied for a provisional patent on it and are reportedly working to commercialize it.
We’ve reached out to the Stanford and Rice teams to see just how their research differs and will update when we’ve received a response.
