Gong, AoyuMaghsoudnia, ArmanCannatà, RaphaelVlad, EduardLomba Lomba, NéstorDumitriu, DanHassanieh, Haitham2025-08-212025-08-212025-07-242025-09-0810.1145/3750718.3750743https://infoscience.epfl.ch/handle/20.500.14299/253377Ultra-Reliable Low-Latency Communication is a key feature of 5G, yet achieving its strict one-way latency target remains challenging in real-world deployments. While previous work proposes latency reduction techniques, most are theoretical or simulation-based and overlook practical bottlenecks in actual systems. In this paper, we analyze and optimize latency with open-source 5G RAN software. We characterize latency sources arising from 5G specifications and implementation-level factors, along with their complex interplays. Guided by this analysis, we introduce improvements reducing one way latency by 39.28 % in the downlink and 55.38 % in the uplink. Our results show the importance of system-level experimentation and provide a blueprint for advancing toward URLLC targets in both 5G and future cellular networks.en5GURLLCSystem-level analysisOpen-source softwaretext::conference output::conference proceedings::conference paper