Exploiting Polarization for Spectrum Awareness in Cognitive Satellite Communications

The continuously increasing demand of spectrum and current static spectrum allocation policies are rendering the available radio spectrum scarce. To address the problem of spectrum scarcity in the satellite paradigm, cognitive Satellite Communications (SatComs) has been considered as a promising technique. In addition to the existing spectrum sharing dimensions such as frequency, time and space, polarization domain can be exploited as an additional degree of freedom in order to explore the spectral gaps in the under-utilized licensed spectrum. In this context, this chapter firstly provides an overview of the existing works in polarization-based spectrum sharing. Secondly, it presents the theoretical analysis of Energy Detection technique for dual polarized Additive White Gaussian Noise (AWGN) and Rayleigh fading channels considering the spectral coexistence scenarios of dual and hybrid satellite systems. Thirdly, it provides the comparison of different combining techniques in terms of the sensing performance in the considered dual polarized channels with the help of theoretical analysis and numerical results. Finally, it provides interesting future research directions in this domain.