Inter-Frequency Cell Mobility Using L1/L2 TCI State Switching
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Solution Overview
Problem
Existing 5G NR communication systems lack efficient methods for inter-cell mobility between different frequencies, particularly in scenarios requiring beam management without RRC involvement, leading to inefficiencies in signaling and load balancing.
Innovation Solution
Implementing L1/L2 based inter-cell mobility by using L1/L2 signaling to update TCI states for PDCCH and PDSCH, allowing UE to switch between cells with different frequencies without RRC signaling, enabling dynamic load balancing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If L1/L2 signaling is used to update TCI states for inter-cell mobility, then signaling overhead is reduced, but the system becomes more complex in managing frequency transitions
Solution Approach 1:
The patent extracts the RRC signaling requirement from the inter-cell mobility procedure, separating it from the L1/L2 beam management signaling. By using L1/L2 signaling (MAC CE or DCI) to update TCI states without RRC involvement, the patent removes the heavy RRC signaling overhead while maintaining the ability to manage frequency transitions through lighter L1/L2 mechanisms.
Solution Approach 2:
The patent segments the mobility management into two independent parts: RRC configuration of multiple TCI states (including inter-frequency cells) and L1/L2 activation/updates of specific TCI states. This segmentation allows the system to pre-configure frequency information in RRC but use lightweight L1/L2 signaling for actual mobility decisions, reducing overall signaling overhead.
2Reliability
If RRC signaling is used for inter-cell mobility, then beam management is reliable, but signaling overhead increases
Solution Approach 1:
The patent applies preliminary action by having the network pre-configure multiple TCI states including inter-frequency cell configurations through RRC signaling before mobility is needed. This pre-configuration ensures reliability by establishing all necessary frequency and beam information in advance, while the actual mobility trigger uses lightweight L1/L2 signaling rather than full RRC procedures.
Solution Approach 2:
The patent introduces dynamics by enabling fast switching between intra-frequency and inter-frequency TCI states through L1/L2 signaling. The system dynamically activates appropriate TCI states based on current mobility needs without requiring static RRC reconfiguration for each frequency transition, reducing signaling overhead while maintaining reliability.
3Adaptability or versatility
If multiple TCI states are configured for different frequencies, then inter-frequency mobility is enabled, but device complexity increases
Solution Approach 1:
The patent makes the TCI state mechanism universal by designing it to handle both intra-frequency and inter-frequency cell configurations through a unified framework. The same TCI state structure and L1/L2 activation procedures work for both cases, allowing UEs to manage multiple frequencies without requiring separate complex mechanisms for each frequency type.
Data Source
AI summary
A method of operating a user equipment, UE, configured with a plurality of transmission configurations associated with one or more cells, each cell associated with a frequency, includes receiving an indication of a transmission configuration to be activated from the plurality of transmission configurations, the indicated transmission configuration including a first frequency that is different from a second frequency of a current transmission configuration. The method includes operating in accordance with the indicated transmission configuration at the first frequency.