It looks like someone has come up with a method of simultaneously transmitting different signals in the same frequency:

A team of Italian radio boffins – and one Swede – have one-upped their pioneering countryman Guglielmo Marconi by demonstrating a method of simultaneously transmitting multiple signals on the same frequency.

“This novel radio technique allows the implementation of, in principle, an infinite number of channels in a given, fixed bandwidth, even without using polarization, multiport or dense coding techniques,” the team explains in a paper in the March issue of the New Journal of Physics.

If refined and commercialized, the technique developed by Fabrizio Tamburini and his team could radically increase the carrying capacity of today’s cramped bandwith of radio, television, Wi-Fi, and wireless telecommunications.

Essentially, it appears to be some sort of phase/geometry trick:

The breakthough achieved by Tamburini and his crew is based on adding orbital angular momentum to the signal-carrying mix, essentially twisting the directed signal in a way that offsets multiple signals in the same frequency.

The signal-spinning Venetian antenna

The team “spun” the signal in their successful demo by simply slicing one radius of a conventional parabolic antenna and raising one end of the slice above the other. Doing so gave the part of the transmitted signal from the elevated section of the antenna a small “head start” on the part from the lower segment.

The sent beam was then encoded with two separate signals timed to occupy opposite angles of the spin, and antennas were set up to receive each of them. Theoretically, much more discrete signal-slicing could fit more signals into the same transmitted frequency.

One beam, two signals received by antennas on either side of the signal’s centerpoint

Team member Bo Thide of Swedish Institute of Space Physics first conceived the orbital angular momentum idea in a 2007 paper focussed on radio astronomy, but in which he wrote that the concept “paves the way for novel wireless communication concepts.”

I’ve heard of some other techniques that will provide similar capabilities, and I would hope that if we do see a massive expansion in the carry capacity of wireless capacity, that much of this delta would be directed away from the incumbent carriers.

If there is any lesson to be learned about the history of data transmission, wired, and wireless, it is that incumbent monopolies, and near monopolies, are the enemies of innovation, not its source, because their profit margins are driven by preserving their monopolies.