Polarization-enabled spectrum opportunities made practical: Polarization Mode Dispersion and learning-throughput tradeoff

Polarization-enabled Spectrum Sharing (PSS) that exploits the spectrum opportunities in polarization domain is deployed to balance between avoiding interference at the incumbent receiver and optimizing the throughput of secondary user. However, when it comes to wideband environments, PSS is impaired by the frequency-dependent Polarization Mode Dispersion (PMD) effect, thus the spectrum efficiency of PSS drops. Different from previous studies on PSS without taking the frequency-dependent depolarization effect into consideration, this work firstly analyzes the PMD effect and then proposes a cluster-based PSS approach to enable PSS on a narrower frequency span for LTE user. Since the width of the frequency span impacts both the environment learning time overhead and the PMD effect suffered by PSS, we analytically incorporate the PMD effect into LTE throughput and the interference at the incumbent receiver. By this means, the optimal number of subcarriers is derived to maximize the effective throughput for LTE users, subject to the interference power constraint at the incumbent receiver.