Researchers at Rice University have figured out how to double mobile data transmission rates without the need to increase the number of cell towers that a network uses. To understand how they did it, you need to know how current mobile networks work. The mobile phones of today use two spectrum channels, think of a two way street, one lane to send information, the other lane to receive it. This is called full duplex. There’s also something called time division duplex, which uses a single spectrum channel, which is like a one way street, to do both the sending and the receiving, but for it to work that single channel cycles rapidly between sending and receiving, never doing both at the same time. What these researchers have done was figure out a way to simultaneously send and receive data using just one channel of spectrum; now picture a one lane bridge that has two levels. To do this they make use of two antennas, which most mobile phones already have, and some custom software at the cell tower. Not only have they shown transmission rates doubling, but they also increased signal quality by an order of magnitude.
The question you’re probably thinking to yourself right now is when will this be used in commercial devices and networks? Ashutosh Sabharwal, Professor of Electrical and Computer Engineering at Rice, says: “I expect people may start seeing this when carriers upgrade to 4.5G or 5G networks in just a few years.” Considering that the LTE-Advanced standard isn’t yet baked, this could mean that we’re not going to see this technology rolled out until the end of this decade. No need to be disappointed however since LTE-Advanced has been tested in the real world by the folks at infrastructure giant Ericsson, and they were able to pull nearly 1 Gbps down while driving around a Swedish city.
Still, it’s progress like this that make us suspicious of the claims operators make that there’s a “spectrum crunch”, when in reality it’s just poor management of spectrum that they already own.
[Photo: Rice University graduate student Melissa Duarte with a “full-duplex” test device.]