Cognitive Radios and Dynamic Spectrum Sharing
Sudharman K. Jayaweera · 2014
The original motivation for cognitive radios came as a natural evolution of software-defined radios (SDR). One possible way to achieve the transfer of spectrum rights is based on static (or off-line) agreements. However, the notion of cognitive radios provided a more flexible alternative in which such spectrum sharing agreements can be achieved dynamically in real time. In spectrum interweave based dynamic spectrum access (DSA) systems, the cognitive secondary radios search for channels that are not being used by a primary user (PU) and access them. Dynamic spectrum leasing (DSL) is motivated by the observation that DSA approach provides no incentive for the PU to share the spectrum with secondary user (SU). The main challenge in dynamic spectrum sharing (DSS) cognitive radios is to ensure that performance of the PU is not compromised due to the presence of SU activity.