Upper bound on the capacity of cognitive radio without cooperation

• Published in: IEEE transactions on wireless communications Vol. 8; no. 9; pp. 4380 - 4385
• Main Authors: Hangyu Cho, Andrews, J.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.09.2009; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Applied sciences; Asymptotic properties; capacity; Cognitive radio; Cooperation; Exact sciences and technology; Fading; Frequency; Interference; Interference constraints; interference temperature; Links; opportunistic; Radio; Radio transmitters; Radiocommunication specific techniques; Radiocommunications; Rayleigh channels; Receivers; Signal processing; spectrum sharing; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Temperature sensors; Transmission and modulation (techniques and equipments); Transmitters. Receivers; Upper bound; Upper bounds; Wireless communication; Fading channels; Transmitter; Data transmission; Scheduling; Cognitive radio; Power allocation; interference temperature; capacity; Upper bound; Signal interference; opportunistic; Rayleigh fading; Transmission loss; Software radio; spectrum sharing
• ISSN: 1536-1276; 1558-2248
• DOI: 10.1109/TWC.2009.071106

We derive an upper bound on the capacity of cognitive radio using the interference temperature concept. We do not assume any cooperation between the primary and the secondary user. First, assuming all four links associated with the primary/secondary transmitter/receiver experience Rayleigh fading, the capacity is achieved via the water-filling power allocation strategy, subject to an average secondary to primary interference to signal ratio (ISR) constraint and a peak ISR constraint. Second, we extend our result to the case with path loss as well as channel fading to reflect the geometric relations between link pairs and network size. Finally, we numerically show that for K P primary receivers which are opportunistically scheduled, the capacity of cognitive radio asymptotically grows as logloglogK P.