Power management for spectrum sharing in cognitive radio communication system: a comprehensive survey

The underlay spectrum access is a very prominent technique in cognitive radio (CR) communication systems in which the primary users (PUs) share the spectrum with the cognitive users (CUs), simultaneously. However, the PU communication is protected by constraining the CUs' transmission power in such a way that the interference power introduced at the PU receiver is under the tolerable limits. In this comprehensive survey, we have presented the general framework of CR communication technology and emphasized on the spectrum accessing and sharing techniques. Various approaches of the optimal power allocation to CUs, namely, the game theory, price auction, convex optimization and iterative water-filling are presented. Moreover, to address the random nature of channel, the performance metrics analysis with the perfect and imperfect channel state information is also illustrated. Finally, the potential issues and research challenges for power management in the CR communication systems are presented which need to be explored.