RRC Re-Establishment for PC5 Relay Link Release Control
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Solution Overview
Problem
The challenge in 3GPP's extended NR technology is the inefficient communication control in UE-to-Network relay scenarios, particularly in releasing and re-establishing PC5 unicast links between terminal apparatuses and base station apparatuses via relay terminal apparatuses.
Innovation Solution
The solution involves a terminal apparatus and base station apparatus with an RRC entity that receives an indication to release a PC5 unicast link from a higher layer, initiating RRC connection re-establishment when determining the link is with a relay terminal apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the terminal apparatus communicates with the base station apparatus via a relay terminal apparatus using PC5 unicast link, then communication coverage is extended, but communication control efficiency deteriorates due to complex link release and re-establishment procedures
Solution Approach 1:
The patent introduces the relay terminal apparatus as an intermediary node between the terminal apparatus and base station apparatus. The relay terminal apparatus manages the PC5 unicast link locally, acting as a mediator that simplifies the control signaling flow. When link release is indicated, the relay terminal apparatus handles the re-establishment procedure, reducing the complexity of direct terminal-to-base station control in relay scenarios.
Solution Approach 2:
The patent segments the communication control into separate domains: the terminal apparatus handles Uu interface (base station) communication, while the relay terminal apparatus handles PC5 interface (sidelink) communication. This segmentation allows each node to independently manage its own link control procedures, improving overall control efficiency by avoiding complex coordinated control across multiple interfaces.
2Reliability
If the RRC entity initiates RRC connection re-establishment upon receiving link release indication, then connection reliability is improved, but processing time increases due to unnecessary re-establishment procedures
Solution Approach 1:
The patent applies local quality by making the link release indication specific to the PC5 unicast link context. The RRC entity determines whether the release indication applies to the PC5 link with the relay terminal apparatus or other links, and only initiates re-establishment procedures when appropriate. This localized handling prevents unnecessary global re-establishment actions, reducing processing time while maintaining reliability for actual link failures.
Solution Approach 2:
Instead of immediately initiating re-establishment upon receiving any link release indication, the patent inverts the logic by first determining whether the indication specifically relates to the PC5 unicast link. The re-establishment procedure is only triggered when the determination confirms the PC5 link is the target, avoiding unnecessary procedures and reducing processing time while maintaining connection reliability.
Data Source
AI summary
A terminal apparatus that communicates with a base station apparatus via a relay terminal apparatus, the terminal apparatus including an RRC entity, in which the RRC entity receives an indication to release a PC5 unicast link from a layer higher than an RRC layer, and initiates a procedure of performing RRC connection re-establishment with respect to the base station apparatus based on determining that the PC5 unicast link is a PC5 unicast link to the relay terminal apparatus.