Methods for Fast Estimation of Primary Activity Statistics in Cognitive Radio Systems

Cognitive Radio (CR) is aimed at increasing the efficiency of spectrum utilisation by allowing unlicensed users to opportunistically access licensed spectrum bands during the inactivity periods of the licensed users. CR systems can benefit from an accurate knowledge of the spectrum occupancy patterns and their statistical properties. This statistical information can be obtained by periodically monitoring (sensing) the idle/busy state of the licensed channels. However, a reliable estimation of the primary activity statistics may require long observations times. This work proposes efficient methods to reduce the observation time required to produce a reliable estimation of the primary activity statistics. Furthermore, a method enabling CR users to quantify the accuracy of the estimated statistics is also proposed. Compared to other existing approaches, the proposed methods can provide accurate estimations of the primary activity statistics in significantly shorter observation times, thus allowing CR users to quickly adapt to new unknown operating channels.