Performance Evaluation of Underlay Cognitive Relayed Networks Under Interference Constraints

Abstract

flow of information is the order of the day. To mitigate the spectrum shortage, researchers brought about the concept of cognitive radio networks towards the end of twentieth century, when data Spectrum scarcity, for long, has been an issue that the researchers have had to deal with, in a world where incessant usage and services were peaking. These networks alleviate the problem of spectrum shortage, either by allowing the unlicensed secondary users (SUs) access to the licensed spectrum when unused (overlay systems) or by sharing the spectrum (underlay systems) with the licensed or primary users (PUs), under certain conditions. The work in this thesis is on underlay cognitive radio networks, where both PU and SU can access the channel simultaneously, as long as the SU transmission does not interfere with the PU communication. This makes interference a constraint in these systems, which also puts a limit on SU transmit powers to ensure no interference with the PU communication when both communicate simultaneously. In this thesis, the cognitive radio networks are analysed under the constraint of interference. newline