Wireless networks all suffer from a basic limitation: interference. Radio signals are waves. If you’re watching Netflix on your iPad via Wi-Fi, the tablet’s antenna is receiving a signal from a transmitter. If no one else is around—and you’re in a room with thick walls that block other radio signals—you’ve got a great connection. If someone else has an iPad in the room, each person ends up with half the maximum data speed. Throw a second Wi-Fi signal into the mix, perhaps from another office or home, and interference becomes an issue. Both signals hit your iPad at the same time, and the device has to try to discern the movie from this noise. People in apartment buildings or at crowded coffee shops know all too well just how shoddy a Wi-Fi connection can be when lots of signals collide.
Cellular operators face similar problems. They would love to put up towers all over the place, but they can’t. Signals from towers bleed into each other, causing interference. One tower covering a certain area works fine until too many nearby users make calls or pull up Web pages at the same time. That’s when data transfer rates fall and calls drop, aka iPhone syndrome.
Perlman had an idea. Interference happens when a device receives multiple signals at once and the wave is muddied. The physics gets very complicated here, but Perlman thought there might be a way to turn interference into a virtue—use that combining property of radio waves to “build” a signal that delivers exactly the right message to your iPad. Multiple transmitters would issue radio waves that, when they reach your tablet, combine to produce a crystal clear signal. If there’s another person in the room with an Android phone or a laptop, the system would take those devices into account so that they, too, received unique waves from the transmitters. Such a system would need to precisely analyze wireless information from the devices at all times, and constantly recalculate the complex combinations of signals from each of the transmitters on the fly. Figuring all that out in real time would of course require some extremely powerful computers.
That, in a nutshell, is DIDO.
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