Sidelink RLM via Dynamic SCI Reference Signal Indication
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Solution Overview
Problem
The existing Radio Link Monitoring (RLM) procedures in NR Uu interface are inadequate for sidelink operations due to the lack of central coordination for Synchronization Signal Block (SSB) signals and the absence of periodic reference signals like Channel State Information Reference Signal (CSI-RS) in sidelink communications.
Innovation Solution
A method for sidelink RLM that involves transmitting a first part of sidelink control information (SCI) containing information about reference signals, allowing RLM measurements to be performed without pre-configured periodic signaling, and using the second part of SCI for decoding data, which includes information about modulation, coding schemes, and HARQ processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pre-configured periodic reference signals (SSB/CSI-RS) are used for RLM measurements, then measurement accuracy is improved, but system complexity and coordination requirements increase
Solution Approach 1:
The patent extracts the RLM measurement function from the traditional pre-configured periodic reference signal framework and implements it using dynamically indicated reference signals within the SCI structure. This removes the need for separate SSB/CSI-RS configuration while maintaining measurement capability, thereby reducing system complexity while preserving measurement accuracy
Solution Approach 2:
The reference signals indicated in SCI serve multiple functions: they enable RLM measurements, support data demodulation, and provide channel estimation. By making these signals multi-functional and dynamically configurable through SCI, the system eliminates the need for separate dedicated RLM reference signals, reducing overall system complexity while maintaining measurement precision
2Reliability
If pre-configured periodic reference signals are used for RLM, then measurement reliability is improved, but adaptability to decentralized sidelink environments deteriorates
Solution Approach 1:
The patent introduces dynamic indication of reference signal parameters through SCI, allowing the transmitting UE to adaptively configure reference signals based on current channel conditions and traffic requirements. This dynamic approach maintains measurement reliability while enabling flexibility in decentralized sidelink environments where UEs autonomously select resources without network coordination
Solution Approach 2:
In decentralized sidelink Mode 2 operations, UEs autonomously perform sensing, resource selection, and RLM without network intervention. The transmitting UE self-configures and indicates reference signal parameters via SCI, and the receiving UE autonomously performs measurements and determines link status. This self-service mechanism ensures both reliability and adaptability in autonomous sidelink operations
3Measurement precision
If separate reference signals are configured for RLM measurements, then measurement precision is improved, but signaling overhead increases
Solution Approach 1:
The patent merges the RLM measurement function with the existing SCI transmission framework by indicating reference signal parameters within SCI messages. Instead of configuring separate dedicated RLM reference signals, the system uses the same reference signals that accompany data transmissions, thereby eliminating redundant signaling while maintaining measurement precision
Solution Approach 2:
The reference signals indicated in SCI serve dual purposes: they enable both data demodulation and RLM measurements. This multi-functionality eliminates the need for separate RLM-specific reference signals and their associated configuration signaling, reducing signaling overhead while preserving measurement precision through proper parameter indication in SCI
Data Source
AI summary
Systems and methods for sidelink Radio Link Monitoring (RLM) are disclosed. In one embodiment, a method performed by a first wireless communication device for RLM for a sidelink between the first wireless communication device and a second wireless communication device comprises transmitting a first part of sidelink control information (SCI) to the second wireless communication device, the first part of the SCI comprising information regarding one or more reference signals that are present on the sidelink for RLM measurements. In this manner, RLM is enabled without the need of (pre-)configured periodic signaling such as Channel State Information Reference Signal (CSI-RS) or Synchronization Signal Block (SSB).