| In underlay Cognitive Radio (CR) systems, secondary users may transmit while primary transmissions take place. However, the interference aggregates on the primary system, and performance degradation will occur. Thus, quantifying and modeling of the aggregate interference is important in characterizing the network's performance. An interference analysis for a Poisson process of CR nodes in a finite area is undertaken while incorporating channel parameters, and a simple Gamma model for the aggregate interference is proposed. Furthermore, a multiple-ring model to replace the annular underlay model will be developed. This model is versatile and mathematically tractable, while being highly accurate. Moreover, the interference from the nearest interferer node is analyzed, and situations where the nearest interferer's interference can approximate the aggregate interference are identified. An outage and asymptotic analysis is carried out for the models. The effect of different system and channel parameters are shown within the numerical results. |
