ABSTRACT
When we look for the meaning of the word “cognition,” it shows the mental process of knowing, including aspects such as awareness, perception, reasoning, and judgment. Similarly, when we frame the name “cognitive radio” (CR), the best denition in Haykin’s words can be quoted as,
The number of mobile users is increasing day by day in the current wireless communication domain, which is apt to create a bandwidth crisis due to limited spectrum availability. CR is a future technology capable of solving the spectrum scarcity problem. It provides a solution by which efcient spectrum utilization is possible by applying the optimistic spectrum sharing techniques [1]. Mitola is considered as the pioneer who brought the concept of CR into existence. In synchrony with the name, CR is capable of detecting dynamically varying environments. Once it senses any changes in the surroundings, it adapts its communication variables such as carrier frequency, bandwidth, power, coding schemes, and modulation scheme in an intelligent way. In this chapter, we basically deal with the fundamental aspects of CR, which include its properties (based on spectrum sensing), an outline of a CR transceiver, and other architectures.
