Abstract-Energy efficiency has become an encouragement, and more than this, a requisite for the design of the nextgeneration wireless communication standards. In this paper, a dual-hop cognitive (secondary) relaying system is considered, incorporating multiple amplify-and-forward relays, a rather costeffective solution. First, the secondary relays sense the wireless channel, scanning for a primary network activity, and then convey their reports to a secondary base station (SBS). Afterward, the SBS, based on these reports and its own estimation, decides cooperatively the presence of primary transmission or not. In the former scenario, all the secondary nodes start to harvest energy from the transmission of primary nodes. In the latter scenario, the system initiates secondary communication via a best relay selection policy. Performance evaluation of this system is thoroughly investigated, by assuming realistic channel conditions, i.e., non-identical link distances, Rayleigh fading, and outdated channel estimation. The detection and outage probabilities as well as the average harvested energy are derived as new closedform expressions. In addition, an energy-efficiency optimization problem is analytically formulated and solved, while a necessary condition in terms of power consumption minimization for each secondary node is presented. From a green communication standpoint, it turns out that energy harvesting greatly enhances the resources of secondary nodes, especially when primary activity is densely present. Index Terms-Cognitive relaying systems, cooperative spectrum sensing, detection probability, energy efficiency, energy harvesting, green communications.
In REF , an algorithm for switching between data transmission and energy harvesting links was introduced in a dual-hop cognitive relaying system.
Green Cognitive Relaying: Opportunistically Switching Between Data Transmission and Energy Harvesting
IEEE Journal on Selected Areas in Communications
IEEE Journal on Selected Areas in Communications
Computer Science Mathematics