Transmitted Reference-Based Spectrum Sensing in IEEE 802.22 WRAN Networks

Cognitive radio (CR) is an effective technology for flexible utility of radio spectrum and has received increasing attention so far. To ensure reliable spectrum sensing, quiet periods (QPs) are allocated during which all secondary users cease transmission and perform spectrum sensing. Such that, regular transmission will be interrupted periodically and the system quality of service (QoS) could be decreased to some extent. In this paper, a spectrum sensing scheme which is based on the transmitted reference (TR) technique is proposed where a secondary signal is transmitted in the first half frame and is reversed to retransmit in the second half one. For the sensing CR user, the first half received signals are delayed and added to the second half ones. By doing so, the strong interference from the other CR user can be alleviated without affecting the spectrum detection performance. Simulation results show that the proposed scheme is very effective and a nearly same detection performance can be obtained comparing with the method when a long enough QP is used.