Experimental Evaluation of Semantic Communications for 6G Networks in Railway Systems

Semantic-aware communication is emerging as a key enabler of 6G networks, shifting the focus from traditional bit-level transmission to context-driven data prioritization. The semantics of information are described through a novel metric called Semantic Quality Indicator (SQI). The Polar-coded SQI is embedded into the Uplink Control Information (UCI) and transmitted via the Physical Uplink Control Channel (PUCCH). By embedding semantic priority directly into uplink control signaling, the system optimizes network resource allocation while maintaining energy efficiency. The proposed scheme is implemented in an open source 5G platform and experimentally validated over an operational railway infrastructure monitoring system. Experimental results demonstrate the effectiveness of PUCCH-based semantic-aware prioritization, achieving improved spectral efficiency, reduced energy consumption, and enhanced transmission reliability. At the same time, the penalty introduced by the SQI integration in PUCCH in terms of bit error rate is negligible.