Achievable Capacity of Multipolarization MIMO With the Practical Polarization-Agile Antennas

In recent years, the polarization domain has attracted significant attention for the 4th and 5th generation (4G/5G) wireless communications owing to its benefit in channel capacity, symbol/bit error rate, and energy efficiency. One driving technology to fully utilize the polarization domain is the polarization-agile antennas that allow flexible reconfiguration of the transmitter (Tx) and receiver (Rx) polarization. The current state-of-the-art polarization-agile antennas can take several discrete polarization angles. This article proposes and analyzed a practical scheme to determine feasible optimal Tx and Rx polarization among the limited number of polarization angles to converge to theoretical channel capacity supported by the discrete polarization-agile antennas with single-RF front-end systems. Both the theoretical and simulation-based analyses for the capacity outage caused by adopting practical discrete polarization-agile antennas are provided in this article to complement communication system design in balancing channel capacity maximization and hardware cost. Comprehensive simulation results demonstrate that the multipolarization multi-input multi-output communication system toward the late revisions of 5G and beyond-5G, so called, 6G wireless communications can successfully reach the theoretically achievable channel capacity with the practical discrete polarization-agile antennas.