RLM-RS Reception Detection for Unlicensed Band Link Quality
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Solution Overview
Problem
In wireless communication systems, especially in unlicensed frequency bands, the uncertainty of channel availability due to contention-based access methods affects the credibility of radio link quality monitoring, leading to inaccurate in-sync or out-of-sync reports, which are critical for maintaining reliable connections.
Innovation Solution
A link quality monitoring method where a terminal detects pre-configured Radio Link Monitoring Reference Signals (RLM-RS) and reports in-sync or out-of-sync status based on reception, rather than estimating hypothetical PDCCH-BLER, improving the accuracy of link quality estimation by considering the reception status of RLM-RS.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the terminal estimates hypothetical PDCCH-BLER based on RLM-RS according to the existing mechanism in NR, then the link quality monitoring can be performed, but the credibility of in-sync or out-of-sync result is significantly affected due to channel availability uncertainty
Solution Approach 1:
The patent changes the fundamental parameter used for link quality assessment from hypothetical PDCCH-BLER estimation to actual RLM-RS reception status detection. By detecting whether the RLM-RS is actually received (presence/absence detection) rather than estimating hypothetical error rates, the system adapts to the unlicensed band environment where channel availability is uncertain, thereby improving both reliability and measurement precision of link quality reports
Solution Approach 2:
The patent replaces the complex hypothetical PDCCH-BLER estimation mechanism with a simpler direct RLM-RS reception detection mechanism. Instead of performing hypothetical BLER calculations based on assumed conditions, the system directly detects the presence or absence of RLM-RS signals, substituting a complex estimation system with a more reliable direct detection approach that works effectively in contention-based unlicensed band environments
2Productivity
If the network-side device transmits RLM-RS at a fixed configured time point, then the terminal can perform periodic monitoring, but the RLM-RS may not be actually sent when the channel is determined not idle through CCA/eCCA
Solution Approach 1:
The patent introduces dynamics into the previously static fixed-time RLM-RS transmission scheme. The network-side device dynamically adjusts RLM-RS transmission timing based on real-time channel availability determined through CCA/eCCA procedures. The RLM-RS is transmitted at the first available opportunity after channel access succeeds, rather than at a predetermined fixed time, allowing the system to adapt to the uncertain channel conditions in unlicensed bands while maintaining monitoring effectiveness
3Reliability
If the terminal continuously monitors link quality in unlicensed bands, then connection reliability can be maintained, but the uncertainty of channel available time due to contention-based access reduces monitoring accuracy
Solution Approach 1:
The patent implements a feedback mechanism where the terminal's direct detection of RLM-RS reception status provides accurate real-time feedback about actual channel availability and link quality. This feedback replaces inaccurate hypothetical BLER estimates with concrete observed data about whether RLM-RS signals are actually received, enabling the network to make informed decisions about connection maintenance and retransmission strategies based on true channel conditions rather than estimates
Data Source
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AI summary
This disclosure provides a link quality monitoring method and a terminal, including: performing detection for a pre-configured RLM-RS to determine whether the RLM-RS is received; and reporting, based on whether the RLM-RS is received, in-sync or out-of-sync used to indicate link quality.