Relay UE PC5 Groupcast Selected System Information
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Solution Overview
Problem
Remote UE devices out of coverage (OoC) cannot receive current system information from a base station (gNB) necessary for network access and relay reselection, leading to potential network access issues and inefficient relay management.
Innovation Solution
A relay UE device transmits selected system information in a PC5 groupcast message, allowing remote UE devices to access and manage relay selection/reselection based on current system information, even when out of coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If remote UE devices are out of coverage, then they cannot receive current system information from the base station, but they still need system information for network access and relay reselection
Solution Approach 1:
The relay UE device acts as an intermediary between the base station and remote UE devices. It receives system information from the base station and forwards selected system information to remote UE devices via PC5 groupcast messages, enabling out-of-coverage devices to access network information without direct base station contact
Solution Approach 2:
The system information is segmented into selected system information that is most relevant for relay selection and network access. The relay UE device transmits only the necessary portions of system information to remote UE devices, reducing information overload while maintaining essential access capabilities
2Loss of information
If relay UE devices transmit all system information to remote UE devices, then complete information is available, but transmission overhead and processing complexity increase
Solution Approach 1:
The relay UE device extracts and selects only the necessary system information elements required for relay selection and network access procedures. It removes unnecessary information from the complete system information set, reducing transmission size and processing requirements while maintaining functional completeness
Solution Approach 2:
Instead of transmitting all system information (excessive action), the relay UE device transmits only the partial set of system information that is sufficient for relay selection and network access. This partial action approach optimizes the balance between information completeness and transmission efficiency
Data Source
AI summary
A relay user equipment (UE) device transmits selected system information in a PC5 groupcast message, where the selected system information is a subset of system information received from a cell at the relay UE device. A remote UE device receiving the PC5 groupcast message with the selected system information obtains at least system information for accessing the cell where such system information may not be available directly from the cell. The remote UE device manages relay selection/reselection at least partially based on the selected system information.