Fundamental issues in cognitive radio

Abstract

The electromagnetic radio spectrum is a natural resource, the use of which by transmitters and receivers (transceivers) is licensed by government agencies. However, this resource is presently underutilized. In particular, if we were to scan the radio spectrum, including the revenue-rich urban areas, we would find that some frequency bands in the spectrum are unoccupied some of the time, some other frequency bands are only partially occupied, and the remaining frequency bands are heavily used. It is therefore not surprising to find that underutilization of the radio spectrum is being challenged on many fronts, including the Federal Communications Commission (FCC) in the United States of America. Cognitive radio1 offers a novel way of solving spectrum underutilization problems. It does so by sensing the radio environment with a twofold objective: identifying those subbands of the radio spectrum that are underutilized by the primary (i.e., legacy) users and providing the means for making those bands available for employment by unserviced secondary users. To achieve these goals in an autonomous manner, multiuser cognitive radio networks would have to be self-organized. Moreover, there would have to be a paradigm shift from transmitter-centric wireless communications to a new mode of operation that is receiver-centric, so as to maintain a limit on the interference produced by secondary user. © 2007 Springer Science+Business Media, LLC.