L1 Mobility Measurement Reporting Using Serving And Candidate Cell RS
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Solution Overview
Problem
Existing communication systems, particularly in 3GPP NR, face challenges in efficiently and flexibly indicating reference signals for Layer 1/Layer 2 Triggered Mobility (LTM) events, leading to increased latency and overhead during cell switching, especially when beam management and mobility enhancements are required.
Innovation Solution
A signaling framework is introduced that allows for efficient indication of reference signals, such as SSB and CSI-RS, for evaluating LTM trigger events, enabling the determination of serving and candidate cell beams, and facilitating Layer 1 measurement reporting without RRC reconfiguration, thereby supporting lower-layer mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional RRC reconfiguration is used for cell switching, then mobility management is reliable, but latency and signaling overhead increase
Solution Approach 1:
The patent segments the mobility management process into two parts: (1) RRC configures measurement parameters and trigger events in advance, and (2) L1/L2 signaling handles the actual cell switching execution. This segmentation allows RRC to prepare measurement configurations while L1/L2 handles rapid cell switching, reducing overall latency while maintaining reliability through divided responsibilities between protocol layers
Solution Approach 2:
The patent implements preliminary action by having RRC pre-configure measurement parameters, reference signal resources, and trigger event thresholds before cell switching is needed. The UE performs measurements and evaluates trigger conditions in advance, so when cell switching is required, the execution can proceed rapidly based on pre-prepared configurations and pre-evaluated measurement results
2Measurement precision
If detailed reference signal configuration is provided for LTM events, then measurement accuracy improves, but signaling overhead increases
Solution Approach 1:
The patent applies universality by configuring reference signal resources that serve multiple purposes: the same reference signals are used for both initial cell search/synchronization and for LTM trigger event evaluation. The TCI states configured for PDSCH reception are reused to identify the reference signals for measurement, eliminating the need for separate dedicated reference signal configurations and reducing signaling overhead while maintaining measurement accuracy
Solution Approach 2:
The patent uses copying by reusing existing RRC-configured reference signal resources and TCI states for LTM measurements instead of creating new dedicated configurations. The L1/L2 signaling references and copies the reference signal identifiers from the existing RRC configuration, avoiding redundant signaling while ensuring the same high-precision reference signals are used for both general reception and specific LTM event evaluation
Data Source
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AI summary
The present disclosure relates to a communication device, a base station and respective methods for a communication device and a base station. For example, the communication device comprises a circuitry and a transceiver. The circuitry, in operation, obtains, from a Layer 1/Layer 2 Triggered Mobility (LTM) control signalling, an LTM trigger event configuration indication. The LTM trigger event configuration indication indicates a configuration of an LTM trigger event that involves reference signals (RS(s)). The involved RS(s) include a serving cell RS and/or a candidate cell RS. The serving cell RS is an RS of a serving cell of the communication device. The candidate cell RS is an RS of an LTM candidate cell for an LTM cell switch of the communication device away from the serving cell. The communication device is to transmit, when the involved RS(s) satisfy a trigger condition of the LTM trigger event, a layer 1 (L1) measurement report for LTM on measurement result(s) of the involved RS(s). The circuitry determines, if the LTM trigger event involves the serving cell RS, the serving cell RS among configured RS(s) of the serving cell with which the communication device is configured based on (i) a serving cell RS indication included in the LTM trigger event configuration indication, and/or (ii) a current serving cell TCI state, wherein the current serving cell TCI state is a TCI state that is currently used by the communication device in the serving cell. Furthermore, the circuitry determines, if the LTM trigger event involves the candidate cell RS, the candidate cell RS among configured RS(s) of the candidate cell with which the communication device is configured based on (i) a candidate cell RS indication included in the LTM trigger event configuration indication, and/or (ii) the current serving cell TCI state. Furthermore, the circuitry determines, by evaluating whether the determined serving cell and/or determined candidate cell RS satisfy the trigger condition, whether to transmit the L1 measurement report. The transceiver, in operation, receives the LTM control signalling, and transmits, if it is determined that the L1 measurement report is to be transmitted, the L1 measurement report.