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MIT Reseachers Propose Faster Wi-Fi With MegaMIMO

Tom Jowitt is a leading British tech freelance and long standing contributor to TechWeek Europe

Bandwidth breakthrough? Boffins in the US reckon new tech can increase wireless data-transfer speed by 330 percent

Researchers at MIT have proposed a much faster wireless system that is able to utilise available spectrum much more efficiently.

The researchers from the Computer Science and Artificial Intelligence Lab (CSAIL) at MIT found that by co-ordinating multiple routers (or access points) at the same time, they were able to achieve much greater data transfer speeds.

Wi-Fi Breakthrough?

Network abstract finger touch wireless wi-fi © flydragon ShutterstockThe researchers noted that as smartphones, tablets and laptops increasingly ditch the hard wire and instead opt for Wi-Fi connectivity, wireless networks are becoming increasingly crowded. And this is causing a “spectrum crunch”.

In this country for example, the communications regulator Ofcom earlier this year called for more 5GHz spectrum to be made available for Wi-Fi routers. It claimed the additional airwaves would allow for quicker, more reliable connections.

But the MIT researchers believe they have the answer, without having to assign more spectrum.

In a paper, a team led by professor Dina Katabi have demonstrated a system called MegaMIMO 2.0 that can transfer wireless data more than three times faster than existing systems.

Another benefit is that it also doubles the range of the Wi-Fi signal.

The technology is soon to be commercialised and essentially it co-ordinates multiple access points at the same time, on the same frequency, without creating interference. This allows MegaMIMO 2.0 to transmit data at a much faster speed, even during high-usage events such as concerts, conventions and football games.

“In today’s wireless world, you can’t solve spectrum crunch by throwing more transmitters at the problem, because they will all still be interfering with one another,” said Ezzeldin Hamed, a PhD student, lead author the paper. “The answer is to have all those access points work with each other simultaneously to efficiently use the available spectrum.”

The researchers tested the performance of MegaMIMO 2.0 in a conference room by setting up four laptops that were mounting on robots. The experiments apparently found that the system could increase the devices’ data-transfer speed 330 percent.

How It Works

Wireless broadband, Wi-Fi © 24Novembers, Shutterstock 2012The researchers point out that smartphones are able to work quickly as they utilise multiple-input multiple-output (MIMO), which means that it uses several transmitters and receivers at the same time.

And as radio waves bounce off surfaces and arrive at the receivers at slightly different times; devices with multiple receiver are able to combine the various streams to transmit data much faster. That is why a router with three antennas works twice as fast as one with two antennas.

But the problem has been how to co-ordinate several routers at once so that they can triangulate the data even faster and more consistently.

“The problem is that, just like how two radio stations can’t play music over the same frequency at the same time, multiple routers cannot transfer data on the same chunk of spectrum without creating major interference that muddies the signal,” said one of the researchers.

So they looked at new ways to co-ordinate multiple transmitters by synchronising their phases. The team developed special signal-processing algorithms that allowed multiple independent transmitters to transmit data on the same piece of spectrum to multiple independent receivers without interfering with each other.

Wi-Fi Delivery

“Since spectrum is scarce, the only way to improve wireless capacity is to add more access points and use some sort of distributed MIMO solution,” said Sachin Katti, an associate professor of electrical engineering and computer science at Stanford University who was not involved in the research.

“While there has long been scepticism that this could ever work in practice, Katabi’s team has demonstrated that they can solve the many practical challenges of distributed MIMO networks.”

The team believe that MegaMIMO 2.0 is not just limited to Wi-Fi, but can also be applied cellular networks.

“This work offers a completely new way to deliver Wi-Fi in campuses and enterprises,” said Katti. “Whereas current solutions often have slow, spotty performance, this technology has the potential to deliver high-capacity connectivity to each and every user.”

And it seems that MegaMIMO 2.0 doesn’t seem to need a lot of specialised kit. Its hardware is packed into a unit the size of a standard router, and includes central processing unit, a real-time baseband processing system, and a transceiver board.

In June the Wi-Fi Alliance announced that businesses will be able to take advantage of faster, more reliable wireless connectivity when new chipsets and routers that support Wi-Fi ‘wave 2’ are available later this year.

It said that MU-MIMO promises more channels and more bandwidth.

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