User Centric Cell-Free Massive MIMO in the O-RAN Architecture: Signalling and Algorithm Integration

Recently, the O-RAN architecture started receiving a lot of interest from the research community. The open interfaces and especially the possibilities for network-wide control protocols via the Near-Real Time RAN Intelligent Controller (Near-RT RIC) provide a great number of opportunities to implement newly proposed algorithms from state-of-the-art research, including solutions supporting cell-free architectures. In this work, we map a clustering and an uplink detection method from the current state-of-the-art to this O-RAN architecture. We identify what is currently possible, and we propose the needed extensions to O-RAN to fully exploit state-of-the-art cell-free processing schemes. We show that we can benefit from these methods whilst introducing only minimal signalling overhead.