Audited Closed-Loop Queue Regulation through PRB Control in a Virtual 5G/O-RAN Testbed

This paper reports an evidence-audited implementation and experimental evaluation of closed-loop regulation of a real radio link control (RLC) queue through discrete physical resource block (PRB) allocation in a virtual 5G/O-RAN testbed. Queue occupancy in bytes is the regulated variable; PRB quota is the actuator; and received UDP throughput is an independently observed performance outcome rather than the controlled setpoint.A causally measured queue, a discrete proportional-integral (PI) law with conditional integration, strict request confirmation, and a bounded prospective protocol are combined with immutable evidence and independent offline replay.An initial calibration was insufficient for its original tuning gate. The first PI configuration terminated after exhausting its command budget and breaching a queue-peak criterion. A revised, frozen configuration completed a 40 s traffic window, 500 raw queue readings, and 395 exactly replayed PI decisions while satisfying its predefined pilot gates.A later 14-attempt replication series yielded 12 full observations, of which 11 satisfied the specified seven pilot gates; two attempts were technically interrupted, and one full attempt failed packet accounting. The mean five-frame queue tracking RMSE across the 12 complete replications was 48.29 kB.These are conditional results for one traffic profile, not evidence of general robustness, absolute capacity or validated M2/M3 models. The contribution is the auditable experimental method and its real implementation, not a novel PI algorithm.