NR Sidelink Discovery User Plane Stack for Out-of-Coverage UEs

The user plane protocol stack is designed to serve multiple functions: it enables direct UE-to-UE discovery communication while also supporting relay scenarios where UEs can discover and communicate with base stations through other UEs. This multi-functional design allows the same protocol infrastructure to handle both direct and indirect discovery scenarios, maximizing discovery opportunities without requiring separate protocol stacks for each case.

The patent introduces a relay UE as an intermediary element that mediates communication between UEs that cannot directly communicate with base stations. The relay UE receives discovery messages from out-of-coverage UEs and forwards them to in-coverage UEs, enabling indirect discovery while maintaining the same user plane protocol stack. This intermediary approach enhances discovery opportunities in coverage edge scenarios without fundamentally changing the protocol complexity.

The system dynamically adapts between direct UE-to-UE communication and base station-controlled communication based on coverage conditions. When UEs are in coverage, the base station can control and monitor the communication for reliability. When UEs move to out-of-coverage areas, the system dynamically switches to direct sidelink communication for maintained efficiency. This dynamic behavior allows the system to optimize for efficiency when possible while falling back to controlled modes when reliability is critical.

The user plane protocol stack is pre-configured with the capability to handle both direct and relayed communication modes. UEs are pre-equipped with the necessary protocol layers and functions to engage in direct sidelink discovery and communication without requiring real-time protocol changes. This preliminary configuration ensures that when direct communication is initiated, it can proceed efficiently with all necessary controls and protocols already in place, maintaining both efficiency and reliability.