Optimization of Detection Time for Channel Efficiency in Cognitive Radio Systems

In cognitive radio (CR) systems, secondary users (SUs) have to detect the channel periodically during their data transmission to decide whether the channel is idle in order to avoid unacceptable interferences to primary users (PUs). The duration of the detection process in a cycle affects the channel efficiency of the SU. Also, the detection time needs to be adaptively adjusted due to path loss variations caused by movements of PUs and SUs. In this paper, we explore the issue on the detection time selection that aims at improving the channel efficiency. We formulate this issue as an optimization problem, but it is extremely difficult to get the explicit solution. A numerical optimization algorithm is proposed to obtain the numerical solution to the problem. Numerical results show that the highest channel efficiency can be achieved by the optimization of the detection time.