Implementation of Cell-Free Radio Access Network Based on O-RAN Architecture

Cell-free massive multiple-input multiple-output (CF-mMIMO) can significantly improve the performance of wireless communication systems, making it a key technology for 6G. Inspired by open radio access network (O-RAN), the paper proposes a user-centric and scalable networking approach for cell-free radio access network (CF-RAN). To achieve distributed baseband processing and scheduling, novel physical and high-layer implementations are designed. By integrating the O-RAN radio intelligent controller (RIC), resource allocation and management for CF-RAN has been studied. On this basis, we develop CF-RAN prototype systems with commercial off-the-shelf (COTS) Sub-6GHz remote radio units (RRUs) and millimeter-wave (mmWave) active antenna units (AAUs), along with experimental results.