Cognitive Radio-Based Smart Grids: From the Perspective of Full-Duplex Primary Users

Cognitive radio (CR) is promising for smart grids (SGs) in terms of overcoming the problem of spectrum inefficiency and interference mitigation. With the intensive research into full-duplex communication technologies, the licensed spectrum available for CR-based SGs (CR-SGs) may be more complex and difficult to use, as more primary traffic exists on the licensed spectrum. As a result, CR-SGs may experience more severe interference from primary users (PUs), and the corresponding transmission opportunities may be impaired. In this paper, based on distinctive polarization features of samples from different PUs, the signal polarization of each PU is extracted from the hybrid samples by studying the polarization similarity of the samples. Based on the signal polarization derived for each PU, the transmitting opportunities for CR-SGs can be derived. Both the interference from CR-SGs to PUs and the throughput of CR-SGs are examined. Numerical results show that the spectrum opportunities for CR-SGs can be guaranteed and that the interference inflicted on PUs is at a satisfactory level.