Terahertz Spectrum Technology May Produce Major Increases in Wireless Network Speeds

Communications Hardware", Image by Tom Blackwell

“Communications Hardware”, Image by Tom Blackwell

Remember when upgrading from a 14.4 baud modem to a 33.6 baud modem felt as though you had moved from bicycle to Indy racing car online? What about when you had DSL installed and you had never experienced anything like it? How about when you next had a T1 line at the office and then a cable modem hooked up at home? All of these drastic jumps in transmission speeds helped to fuel the exponential growth in the web’s evolving architecture, rich and limitless content, and integration into nearly every aspect of modern life.

While the next disruptive jump in speed has yet to occur, researchers and developers are currently working on technology to exploit a still little used area of the electromagnetic spectrum called terahertz (“THz”) waves. Should this come to pass, wireless bandwidth rates could potentially increase by 100 fold or more over today’s WiFi and mobile networks. Beyond increasing the velocity at which videos of cats playing the piano can be distributed and viewed, this technology could have a major impact on the entire world of wireless access, services and devices.

Nonetheless, despite the alluring promise of THz wireless, some key engineering challenges remain to be solved.

The latest significant advance in this early field was reported in a most interesting article posted on Phys.org on September 14, 2015 entitled Physicists Develop Key Component for Terahertz Wireless. (No author is credited.) I will summarize, annotate and pose some of my own questions derived from the blog-wave portion of the spectrum.

A team of researchers from Brown University and Osaka University have developed the “first system for multiplexing terahertz waves”. This is, by definition, a technological means to share multiple communication streams over a single resource such as a cable simultaneously carrying multiple TV channels or phone calls. (However, it is distinctly different from the multiplex movie theaters currently showing a dozen or more of the latest movies at time along with offering way overpriced snacks at the concession stands.) Another device often needed to reverse this process is called a demultiplexer.

The development team’s work on this advancement was published in the September 14, 2015 online edition of Nature Photonics in a paper entitled Frequency-division Multiplexing in the Terahertz Range Using a Leaky-wave Antenna by Nicholas J. Karl, Robert W. McKinney, Yasuaki Monnai, Rajind Mendis & Daniel M. Mittleman. (A subscription is required for full access.)

The “leaky wave antenna” at the core of this consists of “two metal plates place in parallel to form a waveguide“. As the THz waves move across this waveguide they “leak out a[t] different angles depending on their frequency”. In turn, the various frequencies can disperse individual streams of data riding on these THz waves. Devices at the receiving end will be able to capture this data from a unique stream.

According to the researchers, their new approach has the advantage of being able “to adjust the spectrum bandwidth that can be allocated to each channel”. This could be quite helpful if and when their new multiplexer is added to a data network. In effect, bandwidth can be apportioned to the network users’ individual data needs.

The team is planning to continue their development of the THz multiplexer. This includes integrating, testing and improving it in a “prototype terahertz network” they are building. A member of the team and co-author of their paper, Daniel M. Mittleman, hopes that their work will inspire other researchers to join in developing other original THz network technologies.

Assuming that THz wireless networks will be deployed in the future, my questions are as follows:

  • Will today’s wireless service providers adapt their networks if THz technology proves to be technically and economically feasible? Will new providers emerge in the telecom marketplace?
  • What new types of services will become enabled by THz?
  • Will it bring broadband transmission rates to underserved geographic areas around the world?
  • How will providers model and test the elasticity of the pricing for their THz services? Are current pricing schemes sufficient or are new alternatives needed?
  • What entrepreneurial opportunities await for companies developing THz systems and those leveraging its capabilities for content creation and delivery?
  • As more advertising continues to migrate to wireless platforms, how will marketing and content strategists use THz to their advantage?

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