We demonstrate mmSubarray, a novel millimeter-wave sub-band phased array system designed to combat interference and maximize spectrum utilization in mmWave networks. Traditional approaches, such as frequency separation and beam nulling, often lead to spectrum under-utilization or coverage gaps. mmSubarray overcomes these limitations by splitting the spectrum into overlapping and non-overlapping sub-bands, assigning non-overlapping bands to interference-prone directions while using overlapping bands to support other directions. It dynamically allocates sub-bands across multiple beams and employs interference nulling to suppress interference below the noise floor. We built a prototype of mmSubarray using commercially available phased arrays and software-defined radio (SDR). Our experimental results show that the system significantly enhances network efficiency, ensuring robust and reliable communication links without sacrificing spectrum or coverage.

This demo showcases the mm-O-RAN testbed, integrating mmWave arrays with USRP and the OpenAirInterface (OAI) 5G stack. Our system integrates the mmWave array with synchronized Time Division Duplex (TDD) switching and fast beamforming capabilities, using GPIO triggers from the OAI stack. As the first full integration of a mmWave testbed with an OAI 5G stack, mm-O-RAN addresses key challenges in design and implementation, providing a versatile platform for research and experimentation for AI and signal processing algorithms to optimize end-end network performance.