Coordinating multiple access points simultaneously, all on the same frequency and without generating interference, is the premise behind a new form of Wi-Fi called MegaMimo 2.0. When released commercially, as its inventors say it soon will be, it will allow data to be shot through at three times the speed that it travels now and twice as far, the researchers claim.
The Wi-Fi technology, supposedly immune to bottleneck-causing interference, works by letting a number of distinct transmitters send same- and similar-frequency data “to multiple independent receivers without interfering with each other,” the computer scientists, led by Professor Dian Katabi from MIT’s Computer Science and Artificial Intelligence Lab (CSAIL), say in their news release.
Interference removal has always been hard to achieve. Traditionally adjacent and similar frequencies collide with each other and cause interference—in much the same way as two radio stations can’t transmit on the same frequency, CSAIL points out.
The MegaMimo technology is a play on multiple-input, multiple-output (MIMO). That technology already uses lots of radios and antennas to increase the capacity of spectrum. It exploits multipath propagation—where a signal takes many paths. Often that propagation phenomenon can be a problem and cause interference—think ghosting in older analog TV transmissions. But that’s not an issue when it’s managed properly, and it can increase bandwidth.
More speed, more range
In the case of MegaMimo, a “distributed MIMO” technology, it obtains the multiple transmitter and antenna MIMO bandwidth gains, but it also signal-processes the frequencies with algorithms in order to use the same piece of spectrum without interference.
In other words, it achieves the same as MIMO—which we already use in our smartphones, other mobile devices and Wi-Fi routers—but without the interference you’d normally get by using the same frequencies in the same session. Synchronizing the phases, time and frequencies by the algorithm cancels out the crashing signals.
That means you get more speed and more range, the MIT engineers claim in the media release.
MIMO is now common. “Several transmitters and receivers” are used simultaneously when you make a cell phone call, for example.
In that case, “radio waves bounce off surfaces and, therefore, arrive at the receivers at slightly different times,” the release explains. “Devices with multiple receivers, then, are able to combine the various streams to transmit data much faster.”
MIT’s distributed MIMO system co-ordinates the access points better, the researchers say.
Trying to fit more into available spectrum is something scientists have been racing to achieve. One thrust has been to find out how to cancel what’s called self-interference—when transmitting and receiving take place on the same frequency at the same time.
Historically, full duplex, as it’s called, has been impossible to achieve. That’s why you have push-to-talk buttons on walkie-talkies.
In these other cases, algorithms are being tried, too. The scientists are using them to predict, or second guess, the corrupting self-interference and then cancel it.
One of the potential problems with classic MIMO is that there’s a question as to how many transmitters and antennas one can traditionally add before it, too, stops working. That’s why steps forward in the co-ordination and synchronization of the routers and radios is so important.
This article is published as part of the IDG Contributor Network. Want to Join?