Abstract
A design of cognitive radio (CR) signal structure which based on the spectral correlation can be used for active sensing. In this signal structure, the known pilots used for the primary users (PUs) are duplicated and reallocated in the CR transmission signal properly. With this CR signal structure, the received signal of spectrum sensors will become correlated on the subcarriers when PU reoccupation occurs while the CR transmission is active, and thus PU activities can easily be detected by computing the spectral correlation function. As compare with the traditional cyclostationary feature detection scheme, this method can enhance the active sensing performance while remaining the service quality of the CR system, achieving better detection performance in the same detection time, reducing sensing time (about 1/10 of the traditional sensing time), and still reaching the satisfactory outcome even in the circumstances of low SNR and SINR.