2×2 MIMO W-Band Millimeter Wireless Signal Delivery Employing CMA and MRC Technology

Photonics-assisted generation of millimeter-wave (MMW) signals can support larger modulation bandwidths compared with electronic algorithms so that it is considered as a key technology for future Radio-over-Fiber (RoF) communications. Meanwhile, multi-input multi-output (MIMO) system can concentrate the signal energy in an extremely narrow beam in space and precisely directed to the downlink users, thereby maximizing the propagation distance in that direction. Therefore, we demonstrate a W-band photonics-assisted MMW 2 × 2 MIMO communication system. We employ a photo-generated millimeter wave approach to generate a 93.7 GHz W-band signal, which is received according to the maximum ratio combining (MRC) technique and constant modulus algorithm (CMA) equalization algorithm after 2 × 2 MIMO wireless transmission, and carrier recovery using advanced digital signal processing (DSP) algorithms. According to the experimental results, the maximum signal-to-noise ratio (SNR) gain between 1 × 1 and 2 × 2 MIMO can up to 7.1 dB. To the best of our knowledge, this is the first experimental demonstration of high gain in a W-band MMW 2 × 2 MIMO system by using these technologies. For subsequent studies, we also experimentally explored the performance gain of the 2 × 2 dual-polarization MIMO system, the 2 × 2 dual polarized MIMO can achieve a SNR gain of 2.9 dB. These results will provide significant assistance in our future efforts to increase the distance of MMW or even terahertz-band RoF communications.