Abstract
Cognitive radio is considered as the most intelligent solution to enable flexible use of the frequency spectrum. It allows the secondary user to use the band in which the primary user is idle. Spectrum sensing is a major task in cognitive radio systems. In this task, the secondary user is required to sense the frequency spectrum and vacate the band once the primary user is detected. The actual utilization and the achievable throughput of a cognitive radio system depend on the correctly detected holes and the spectrum sensing time. In this paper, a new adaptive sensing time technique based on the Signal-to-Noise Ratio (SNR) is proposed to improve the actual spectrum utilization and the achievable throughput.