Radio Link Monitoring via SSB Circular Mapping in 5G Unlicensed Bands
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Solution Overview
Problem
Current wireless communication systems, particularly in 5G networks, face challenges in efficiently providing services over unlicensed bands due to limitations in channel access procedures, which affect radio link monitoring and quality assessment, leading to potential radio link failures and incorrect quality determinations.
Innovation Solution
The method involves configuring user equipment (UE) and base stations to perform radio link monitoring (RLM) using synchronization signal blocks (SSB) and physical broadcast channels (PBCH) circularly mapped based on subcarrier spacing, allowing for efficient channel access and accurate monitoring of radio link states even in unlicensed bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If radio link monitoring is performed using conventional channel access procedures in unlicensed bands, then channel access can be maintained, but the reliability of radio link monitoring deteriorates due to transmission failures and incorrect quality assessments
Solution Approach 1:
The base station performs channel access procedure in advance before transmitting RLM-RS, and notifies the UE of the transmission status through indication information. This preliminary action ensures that the UE only monitors RLM-RS when successfully transmitted, preventing incorrect quality assessments due to failed transmissions.
Solution Approach 2:
The base station provides feedback to the UE about whether RLM-RS transmission was successful through indication information. This feedback mechanism allows the UE to adjust its monitoring behavior accordingly, improving the reliability of radio link monitoring by preventing false quality assessments.
2Measurement precision
If radio link monitoring is performed in unlicensed bands without considering channel access status, then monitoring can be continuously performed, but the accuracy of quality assessment deteriorates due to failed transmissions
Solution Approach 1:
The base station performs channel access procedure before transmitting RLM-RS and notifies the UE of the transmission status. This preliminary action ensures that quality assessment is only performed on successfully transmitted signals, improving measurement precision.
Solution Approach 2:
The base station provides feedback about transmission success to the UE, enabling the UE to accurately assess signal quality only when transmission was successful, thereby improving both measurement precision and monitoring reliability.
3Productivity
If conventional RLM procedures are used in unlicensed bands, then existing monitoring mechanisms can be maintained, but service provision efficiency deteriorates due to increased radio link failures
Solution Approach 1:
The base station performs channel access procedure before transmitting RLM-RS and notifies the UE of transmission status. This prevents unnecessary retransmissions and radio link failures, improving both service provision efficiency and radio link stability.
Solution Approach 2:
The feedback mechanism about transmission success allows the UE to efficiently manage radio link monitoring, reducing unnecessary retransmissions and improving overall service provision efficiency while maintaining stable radio links.
Data Source
AI summary
A method performed by a user equipment (UE). The method including receiving radio link monitoring (RLM) configuration information from a base station; identifying a synchronization signal block (SSB) index included in the RLM configuration information; identifying, in a RLM-reference signal (RS) transmission duration, at least one candidate synchronization signal/physical broadcast channel (SS/PBCH) block circularly mapped on the SSB index, based on an index of the at least one of the candidate SS/PBCH block and a number of SSB identified according to subcarrier spacing; and performing RLM based on the at least one identified candidate SS/PBCH block.