Study of spectrum sensing exploiting polarization: From optimal LRT to practical detectors

Spectrum sensing exploiting polarization can be leveraged to improve detection performance. In this paper, we present an optimal likelihood ratio test (LRT) which serves as the upper bound on the performance of all methods that exploit polarization under Gaussian assumption. However, the performance of LRT for realistic blind sensing is unclear since the practical implementation of polarization sensing has to face several challenges, which is the focus of this paper. Four practical sensing algorithms utilizing polarization are considered in this work, that is, a generalized likelihood ratio test (GLRT) for polarization sensing using maximum likelihood estimate (MLE) method when any prior knowledge is unknown, an optimal test when the noise of channel between primary user and secondary user is partially polarized, a realistic detector considering that the received polarization wave arrived with a specific direction rather than is almost perpendicular to the receiver dual-polarized antennas, and a more practical blind detector for polarization channel exhibiting polarization mode dispersion (PMD) phenomenon especially in wideband system. The simulation results show the performance gains possible with proposed detectors and how well the proposed detectors are expected to perform in practice.