Enhancing URLLC Performance in 5G Networks Through Hybrid ARQ Feedback for eMBB and URLLC Multiplexing in Grant-Free Resources

In 5G uplink (UL) transmission, Ultra-Reliable Low-Latency Communication (URLLC) and Enhanced Mobile Broadband (eMBB) users may simultaneously utilize the same grant-free (GF) resources, leading to potential collisions and performance degradation for URLLC. This paper introduces a two-step strategy to mitigate this issue. First, an overlap indication is employed to notify URLLC users of potential resource conflicts with eMBB transmissions. Second, explicit Hybrid Automatic Repeat Request (HARQ) feedback or an additional scheduling request (SR) is proposed to improve URLLC performance. Simulation results demonstrate a significant reduction in error probability caused by Demodulation Reference Signal (DMRS) miss-detection, ensuring URLLC’s stringent reliability and latency requirements are met while optimizing resource efficiency. These findings highlight the potential of combining explicit HARQ feedback and overlap indicators to enhance multiplexing in GF resources.