The throughput potential of cognitive radio: A theoretical perspective

Cognitive radios are promising solutions to the problem of overcrowded spectrum. In this article, we explore the throughput potential of cognitive communication. Different interpretations of cognitive radio that underlay, overlay and interweave the transmissions of the cognitive user with those of the licensed users are described. Considering opportunistic communication as a baseline, we investigate the throughput improvements offered by the overlay methods. Channel selection techniques for opportunistic access such as frequency hopping, frequency tracking and frequency coding are presented. The tradeoff between regulation and autonomy inherent in the design and performance of cognitive networks is examined through a simple example, which shows that the optimal amount of licensing is proportional to the duty cycle of the traffic arrivals. I