Terminal Radio Link Failure Signaling via Sidelink Relay
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Solution Overview
Problem
Current communication systems in 3GPP, particularly in 5G NR, face challenges in efficiently managing radio link failures between terminal apparatuses and base stations using direct and indirect paths without proper signaling radio bearers, leading to communication disruptions.
Innovation Solution
A terminal apparatus is designed to detect radio link failures on direct paths and, if a signaling radio bearer is not configured on the indirect path, it transmits information about the failure via a sidelink signaling radio bearer to a relay terminal apparatus, which then forwards this information to the base station, ensuring seamless communication by utilizing both direct and indirect paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a terminal apparatus uses only a direct path for communication with the base station, then the communication path is simple, but radio link failure causes complete communication disruption
Solution Approach 1:
The communication path is segmented into multiple independent paths: a direct path (Uu interface) and an indirect path via relay terminal apparatus. Each path can operate independently, allowing the system to maintain communication through one path even if the other experiences radio link failure, thus improving reliability without requiring complex centralized control
Solution Approach 2:
A relay terminal apparatus is introduced as an intermediary node on the indirect path. When the direct path fails, the relay terminal apparatus mediates communication between the terminal apparatus and the base station, enabling seamless failover and maintaining communication continuity
2Reliability
If the terminal apparatus waits for base station notification of radio link failure, then the signaling protocol is simple, but communication disruption occurs before failure detection
Solution Approach 1:
The terminal apparatus monitors the radio link status and generates feedback information about detected failures. This feedback mechanism allows the terminal to proactively notify the base station about path failures, enabling timely detection and response without requiring complex base station-side monitoring
Solution Approach 2:
The terminal apparatus performs preliminary detection of radio link status and prepares failure notification before the base station can detect or respond to the failure. This preliminary action ensures that the base station is informed immediately, allowing for rapid failover decision-making
3Reliability
If the signaling radio bearer is configured on both direct and indirect paths as a split bearer, then communication redundancy is maximized, but the bearer configuration becomes complex
Solution Approach 1:
The bearer configuration is made dynamic rather than static. The system can adaptively configure the signaling radio bearer on different paths based on real-time radio link conditions, allowing the terminal to select the most appropriate path for signaling transmission without requiring complex pre-configured split bearers on all paths
Data Source
AI summary
A terminal apparatus for communicating with a base station apparatus by using a direct path and an indirect path determines whether a signaling radio bearer is configured on the indirect path in a case that radio link failure is detected on the direct path and the signaling radio bearer is not configured with a split bearer, and a transmitter transmits information indicating that the radio link failure has occurred on the direct path via a sidelink signaling radio bearer configured between the terminal apparatus and the relay terminal apparatus in a case that the signaling radio bearer is determined to not be configured on the indirect path.