They are also expected to play a major role in tactical communications for the U.S. Navy and for the Department of Defense,” said Thomas Hou, professor of electrical and computer engineering in the College of Engineering at Virginia Tech.
However, a major technical obstacle remains and that is the availability of frequency space on an already crowded wireless array of networks.
Hou and his colleagues Wenjing Lou of computer science and Hanif Sherali of industrial and systems engineering have proposed some novel solutions for spectrum sharing that may avoid the presence of interference.
Both the National Science Foundation (NSF) and the Office of Naval Research (ONR) are funding their work on efficient spectrum sharing, although each grant addresses different types of problems and different application domains.
Cognitive radios are valued because they will configure to their environment and their user’s needs. The new cognitive radios are similar to living creatures in that they are aware of their surroundings and understand their own and their user’s capabilities and the governing social constraints. Under development for more than a decade, cognitive radio transmission still faces challenges.To address some of these issues, the NSF project, valued at $500,000, is aimed at a much higher efficiency sharing of the spectrum where the networks actually coexist.
“But if we can somehow configure secondary nodes not to be felt by the primary nodes, then we can achieve transparent coexistence,” Hou added. This is the main research theme of the NSF grant.
Specifically, the team plans to explore the potential of the simultaneous activation of a secondary network with the primary network, as along as the interference produced by secondary nodes can be properly controlled (e.g., canceled) by the secondary nodes. That is, secondary users share the spectrum in a much more aggressive manner than the interference-avoidance paradigm.
“Here, secondary nodes are allowed to be active as long as they can cancel their interference to the primary nodes in such a way that the primary nodes do not feel the presence of the secondary nodes. “Activities by the secondary nodes are made in a transparent or invisible way to primary nodes,” Hou explained.
Under this paradigm, secondary nodes use powerful physical layer capabilities to handle interference cancellation. “Further, the burden of this interference cancellation will solely rest upon the secondary nodes so as to be truly transparent or invisible to primary nodes. As expected, such a paradigm has the potential of offering much greater spectrum efficiency and network capacity than those under the existing paradigm,” Hou added.
The second grant, awarded by the ONR and valued at $300,000, will allow Hou, Lou and Sherali to look at specific spectrum-sharing methods for tactical communications.
In this project, they will explore a new spectrum-sharing method for DoD and the Navy’s cognitive radio ad hoc networks. The proposed method is called cooperative sharing, specifically targeted to the application scenario where the DoD or Navy’s ad hoc network, in the role of a secondary network, wishes to access the radio spectrum in a friendly environment where the underlying spectrum is owned by allied coalition forces network.With this method, a secondary network and the primary network share each other’s network resource or nodes in a cooperative and friendly manner. “Although packets from the primary network may still enjoy priority over packets from the secondary network, packets from either network will take advantage of the nodes in the other network on their way to their destinations,” Hou explained.
Hou is the co-editor of Cognitive Radio Communications and Networks: Principles and Practice, adopted as a textbook by a number of universities around the world. Lou has a NSF CAREER Award based on the study of wireless networks. Sherali, a member of the National Academy of Engineering, is world-renowned for his abilities in designing optimization algorithms.
Lynn A. Nystrom | Newswise
LandKlif: Changing Ecosystems
06.07.2018 | Julius-Maximilians-Universität Würzburg
“Future of Composites in Transportation 2018”, JEC Innovation Award for hybrid roof bow
29.06.2018 | Fraunhofer-Institut für Lasertechnik ILT
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Transportation and Logistics
16.07.2018 | Agricultural and Forestry Science