Direct-detection PDM-OFDM RoF system for 60-GHz wireless MIMO transmission without polarization tracking. - Hou-Tzu Huang; Chung-Shin Sun; Chun-Ting Lin; Chia-Chien Wei; Wei-Siang Zeng; Hsi-Yu Chang; Boris Shih; Anthony Ng'oma (OFC, 2015)