Cognitive and Software Radios

Representative spectrum usage plot showing many open channels available for use

Representative spectrum usage plot showing many open channels available for use

Software and cognitive radios have promised to significantly enhance the performance of wireless systems. Yet, significant hurdles have to be overcome in order to achieve seamless performance similar to that in a traditional radio.  Software radios change the game by attempting to make the system completely adaptive. Many radio functions are actually implemented in software, allowing updates and changes on-the-fly. Cognitive radios represent the evolution of software radios, where the system has an additional awareness and ability to optimize itself through a closed feedback loop. The biggest promise by both systems is flexibility, especially in the operational frequency. An important application of these radios is in dynamic spectrum access, where open frequency bands (as shown in the spectral plot) are sensed and occupied.

The implication for antennas is that very wide bandwidths must be supported with high efficiency and good radiation characteristics; such features are very challenging to accommodate simultaneously. My work has explored the development of antennas to support various features likely to be used by cognitive and software radios. The following list gives a short summary of different studies I have conducted in this area.

  • Software and Cognitive Radio Base Station Antennas: there is a need to develop antennas maintaining good radiation patterns (leading to good signal strength) in one sector of space. By using frequency reconfigurability, the antenna can switch between multiple states, where each state has a different frequency band of operation to further extend the bandwidth of the antenna.
  • Rejection Reconfigurable Antennas: when using wideband, omnidirectional antennas, it is very easy for strong signals to infiltrate the receiver and spectrum sensing system, often saturating components like the LNA, mixers, and the ADC’s. I am striving towards the development of rejection reconfigurable antennas, with the goal to strongly reject the blocker power while maintaining a broadband performance.

For further details, please consult the related publications shown in the list below. Feel free to also send me an email at jmkovitz@ucla.edu so that I can send you the article.

Related Publications