Orthogonally Dull-Polarized Antenna Based Cooperative Cognitive Radio Networking

This chapter is concerned with enhancement of spectrum efficiency/utilization by using polarization enabled two-phase cooperation between primary users (PUs) and secondary users (SUs) for cooperative cognitive radio networking (CCRN). Specifically, we aim to exploit the degrees of freedom provided by orthogonally dual-polarized antennas (ODPAs) to attain an interference-free two-phase cooperation framework. The use of ODPAs enables concurrent transmissions of multiple independent signals of PUs and SUs, and interference suppression via polarization zero-forcing and polarization filtering to obtain significant performance improvement. By leveraging both temporal and polarization domains, a polarization based two-timescale CCRN scheme to improve spectrum efficiency/utilization is presented. To maximize a weighted sum throughput of PUs and SUs under energy/power constraints, the problem is formulated and solved based on a multi-timescale Markov decision process, and two modified backward iteration algorithms are devised to attain the optimal policies. Numerical and simulation results validate the effectiveness of the proposed framework for CCRN, showing that the obtained policy outperforms both greedy and random ones.