Demonstration of Flexible mmWave Digital Beamforming Transmitter using Sigma-Delta Radio-Over-Fiber Link

This work demonstrates a millimeter-wave digital beamforming transmitter based on a sigma-delta radio-over-fiber link. The digital beamforming is controlled from a central unit and distributed to a remote radio unit using a standardized quad small form-factor pluggable 28 (QSFP28) fiber connection. The experimental results demonstrate 26.2 GHz transmission with high-quality beamforming functionality up to 130 MHz effective radio bandwidth at 2.2 m wireless distance. The solution offers a flexible transmitter solution suitable for millimeter-wave distributed active antenna systems.