Feeds

Wireless breakthrough: one frequency, multiple signals

Italian team doubles-up on Guglielmo Marconi

Securing Web Applications Made Simple and Scalable

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.

Since Marconi first demonstrated wireless communications in 1895 – building on previous research undertaken by Nikola Tesla, Heinrich Hertz, Michael Faraday and others – transmissions have been encoded using various combinations of phase, frequency, and amplitude modulation. All well and good, but signals are limited to transmission within a single (or frequency-hopping) slice of bandwidth.

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.

Multiple-signal demonstration antenna

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.

Diagram of Venetian radio demonstration

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."

Last year, Tamburini, Thide, and their team demonstrated the multiple-signal technique by beaming two separate audio signals at 2.4GHz, then two television signals, 442 meters from the lighthouse of Venice's San Giorgio Island to the balcony of the Palazzo Ducale.

"It's exactly the same place that Galileo first demonstrated his telescope to the authorities in Venice, 400 years ago," Thide told BBC News.

As Thide noted, those authorities were skeptical. "They were not convinced at all; they could see the moons of Jupiter but they said, 'They must be inside the telescope, it can't possibly be like that.' To some extent we have felt the same [disbelief from the community], so we said, 'Let's do it, let's demonstrate it for the public'." ®

HP ProLiant Gen8: Integrated lifecycle automation

More from The Register

next story
Malaysian Airlines flight MH17 claimed lives of HIV/AIDS cure scientists
Researchers, advocates, health workers among those on shot-down plane
The Sun took a day off last week and made NO sunspots
Someone needs to get that lazy star cooking again before things get cold around here
Mwa-ha-ha-ha! Eccentric billionaire Musk gets his PRIVATE SPACEPORT
In the Lone Star State, perhaps appropriately enough
MARS NEEDS OCEANS to support life - and so do exoplanets
Just being in the Goldilocks zone doesn't mean there'll be anyone to eat the porridge
Diary note: Pluto's close-up is a year from … now!
New Horizons is less than a year from the dwarf planet
Forty-five years ago: FOOTPRINTS FOUND ON MOON
NASA won't be back any time soon, sadly
prev story

Whitepapers

Top three mobile application threats
Prevent sensitive data leakage over insecure channels or stolen mobile devices.
The Essential Guide to IT Transformation
ServiceNow discusses three IT transformations that can help CIO's automate IT services to transform IT and the enterprise.
Mobile application security vulnerability report
The alarming realities regarding the sheer number of applications vulnerable to attack, and the most common and easily addressable vulnerability errors.
How modern custom applications can spur business growth
Learn how to create, deploy and manage custom applications without consuming or expanding the need for scarce, expensive IT resources.
Consolidation: the foundation for IT and business transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.