Dual-Band Wireless Fronthaul Using a FSS-Based Focal-Point/Cassegrain Antenna Assisted by an Optical Midhaul

This work reports the concept and implementation of a dual-band wireless fronthaul (FH), using a frequency selective surface (FSS)-based focal-point/Cassegrain antenna, assisted by an optical midhaul (MH). Our innovative fiber-wireless architecture enables to achieve simultaneous and extended-reach transmission over two distinct bands, namely C- and Ka-bands. The dual-band wireless FH is ensured by employing a dual-band antenna, consisting of a conventional main reflector (paraboloid) and a subreflector based on a frequency selective surface, which allows integrating a focal-point and a Cassegrain system in the same structure. It presents gain from 30 to 39.4 dBi and bandwidth from 1.1 to 4.3 GHz at 7.45 and 28 GHz, respectively. The optical MH relies on applying a dual-drive Mach-Zehnder modulator for simultaneously modulating both RF signals at the same wavelength and distribute them through a 25 km fiber optical link. Finally, the RF carriers at 7.5 and 28 GHz are radiated by the FSS-based antenna over dozens of meters wireless link. Experimental results demonstrate throughput up to 18 Gbit/s with error vector magnitude in accordance to the 3GPP Release 15 requirements, giving rise to a potential technological solution for increasing the system range, as well as reducing capital expenditure costs, footprint, weight and complexity.