Optical True Time Delay Pools Based Centralized Beamforming Control for Wireless Base Stations Phased-Array Antennas

In this paper, we propose a novel centralized beamforming control system, using optical true time delay pools (OTTD-Ps), for multiple base stations (BSs) of wireless communication with phased array antennas (PAAs). In this proposed system, the predesigned OTTD-P with an interconnection matrix and a wavelength-controlling matrix is employed to control microwave beam steering and the controlling function is carried out in a central station (CS). A dense wavelength division multiplexing based demultiplexer is used to replace tunable filters in the BS and the cost-effective multiwavelength laser source is employed to generate uniformly spaced optical carriers in the CS. Without tunable filters and controlling modules, as well as the controlling function of beamforming in different BSs being concentrated in the CS, the complexity and cost of BSs can be greatly reduced. Finally, a proof-of-concept system employing OTTD-P with 24 wavelengths and four-element antennas, which are able to form seven basic PAA beams, is demonstrated. The obtained results successfully verify the feasibility of the proposed scheme.