MAC Layer Shortcuts for Low-Latency Intra-RAN UE Communication

Low latency communication is critical for supporting latency-sensitive applications in beyond 5G and 6G networks. While there have been various advancements in optimizing the latency, current network architectures still route data traffic between User Equipments (UEs) connected to the same gNodeB (gNB) through the core network. This causes unnecessary delays and resource consumption that could otherwise be avoided. This paper proposes a novel approach to optimize intra-RAN UE communication by introducing "shortcuts" at the Medium Access Control (MAC) layer of the gNB. By enabling direct data forwarding between UEs connected to the same RAN, the proposed approach reduces end-to-end latency. This is achieved by bypassing higher layers in the gNB and the core network for eligible traffic. A proof-of-concept implementation by modifying the MAC layer of the srsRAN project, an open-source 5G RAN, demonstrates the viability of such an approach. The implementation and further analysis demonstrate measurable end-to-end latency reduction and improved consistency. Such an approach holds significant potential for optimizing intra-RAN UE communication.