Design of a New Signal Structure for Active Sensing in Cognitive Radio Systems

Spectrum sensing is one of the major elements of cognitive radio (CR) systems. The periodic spectrum sensing frame structure can provide reliable sensing agility by introducing sensing quiet periods among signal frames to protect the primary users (PUs) from interference. However, arranging too many intra-frame sensing quiet periods on CR signaling may degrade the quality of service (QoS) of the CR network. To solve this problem, active sensing, performing spectrum sensing and transmitting data simultaneously, has been proposed to replace the intra-frame sensing. One drawback of active sensing is that the sensing performance becomes limited due to the interference from CR network transmissions. In this paper, a new CR signal structure for active sensing based on the cyclostationary properties is proposed, with which the active sensing performance can be further improved while maintaining the QoS of the CR system. Simulation results show that the proposed method significantly improves the detection performance of active sensing, especially when the signal strength from PUs is sufficiently low.