PC5 Relay Triggering for R18 Multipath Path Establishment
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Solution Overview
Problem
The existing R17 method for triggering relay UE to enter a connected state is ineffective in the R18 multi-path architecture, as the SRB1 message, including the RRC reconfiguration complete message, is highly likely to be transmitted directly on the direct link, making the R17 method unreliable for ensuring timely state transition of relay UE.
Innovation Solution
A new PC5 RRC message is used by the first UE to trigger the relay UE to enter a connected state based on the transmission path configuration of the SRB1, allowing for successful multipath establishment by determining whether to send a PC5 RRC message depending on the path configuration, whether direct or indirect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the R17 method is used to trigger relay UE to enter connected state by sending RRC message on indirect link, then the relay UE can be triggered to enter connected state, but the method becomes unreliable in R18 multi-path architecture where SRB1 message is transmitted on direct link
Solution Approach 1:
The patent introduces dynamic adaptability by making the triggering method flexible based on path configuration. The first UE determines whether to send PC5 RRC message based on whether indirect path is configured, allowing the system to adapt between direct and indirect triggering methods depending on the active path configuration, thus maintaining reliability across different scenarios
Solution Approach 2:
The patent changes the triggering parameter from fixed R17 method to a conditional approach where the triggering mechanism (PC5 RRC message) is applied selectively based on path configuration parameters. This parameter-based adaptation ensures the relay UE is reliably triggered regardless of whether direct or indirect path is used for data transmission
2Speed
If a new PC5 RRC message is sent to trigger relay UE to enter connected state, then the relay UE can promptly enter connected state, but the message transmission complexity increases
Solution Approach 1:
The patent uses PC5 RRC message as an intermediary triggering mechanism that operates independently of the data transmission path. This intermediary approach allows the relay UE to be triggered directly via PC5 interface without waiting for indirect path message delivery, thus improving state transition speed while keeping the data path complexity unchanged
Solution Approach 2:
The patent segments the triggering function from the data transmission function. The PC5 RRC message handles only the triggering aspect, while data transmission continues to use the configured path (direct or indirect). This segmentation allows the triggering mechanism to operate independently and efficiently without complicating the overall data transmission system
Data Source
AI summary
This application discloses a path establishment method including: determining, by first user equipment (UE), based on a transmission path configuration of a signaling radio bearer SRB1 carrying Uu signaling, whether to send a PC5 radio resource control RRC message to relay UE, where the PC5 RRC message is used to trigger the relay UE to enter a connected state; where a transmission path corresponding to the transmission path configuration of the SRB1 carrying Uu signaling includes at least one of the following: an indirect path between the first UE and a network-side device, and a direct path between the first UE and the network-side device; where the indirect path includes a PC5 link between the first UE and the relay UE and a Uu link between the relay UE and the network-side device.