Adaptive Photonics-Aided Coordinated Multipoint Transmissions for Next-Generation Mobile Fronthaul

We propose and demonstrate a concept of photonics-aided coordination for multi-cell downlink transmissions. The concept targets reliable high-throughput applications for future-proof millimeter-wave small cells based on radio-over-fiber fronthaul. Based on the physical properties of millimeter waves and the phase and magnitude relationship during optoelectrical conversion, a photonics-aided coordination module is proposed, which adjusts the overall channel matrix of optical wireless transmissions in order to achieve a distortion-free reception. Exploiting the multitude and density of remote access units, we specifically propose three methods of coordination, namely, photonics-aided amplification, synthesis, and interference cancellation, which directly enhance the signal-to-noise ratio, increase the throughput, and mitigate the interference of cell-edge users, respectively. These methods are realized at the physical layer and can be transparent to data, which reduces the coordination overhead. Prototypes, involving end-to-end downlink transmissions, are established, which demonstrate the feasibility and effectiveness of the proposed methods for both scalar and vector signals.