Virtual channel space-time processing with dual-polarization discrete lens antenna arrays

This paper discusses channel capacity improvements with optimal multiantenna wireless communications using a discrete lens array (DLA) at the analog front end. It is first shown that optimal signaling over multiantenna channels via virtual spatial models (VSMs) has a direct hardware correspondence in a multibeam spatially fed antenna architecture. A multibeam dual-polarized DLA is designed and characterized, and the effects of measured antenna radiation patterns on calculated capacity are quantified. In particular, the paper examines: 1) effects of cross-polarization for a dual-polarized multibeam array; 2) effects of beam overlap in a multibeam array; and 3) effects of gain variations for different scan angles. It is demonstrated that adding an ideal dual-polarized array achieves a capacity improvement of up to 88% compared to the single-polarization case. In practice, the two polarizations are weakly coupled, and the measured cross-polarization level of -14 dB decreases the capacity of the system by less than 2%. Furthermore, it is shown that a dual-polarized multibeam DLA is nearly insensitive to polarization rotation in a rich scattering environment, whereas single-polarized antennas incur a capacity degradation of up to 24%. Finally, capacity decrease due to measured nonuniform amplitudes on the antenna aperture is shown to be less than 10%.