L1/L2 Inter-Cell Mobility with Candidate DU Timing Coordination
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Solution Overview
Problem
Current 5G wireless networks face challenges in reducing interruption time and signaling overhead during L1/L2-based inter-cell mobility due to the lack of necessary information about target cell configuration, leading to longer latency and increased interruptions.
Innovation Solution
The proposed solution involves providing user equipment (UE) with lower layer signaling messages from the DU, including an indicator or identity of the candidate cell, timing offset, and TCI state information, enabling coordinated L1/L2 inter-cell mobility execution with candidate DUs associated with the same CU.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If L1/L2-based inter-cell mobility is implemented without target cell configuration information, then mobility speed is improved, but interruption time increases and reliability deteriorates
Solution Approach 1:
The patent applies preliminary action by providing the UE with target cell configuration information (timing offset, TCI state, carrier frequency, SSB index) before the actual mobility execution. This allows the UE to prepare necessary communication parameters in advance, ensuring reliable communication is established immediately upon cell switching without interruption or data loss.
2Reliability
If complete L2/L1 reset is performed during inter-cell mobility, then reliability is improved, but loss of time increases
Solution Approach 1:
The patent extracts only the essential configuration information needed for immediate communication (timing offset, TCI state, carrier frequency, SSB index) from the complete L2/L1 configuration, providing just enough information to the UE to maintain communication reliability without requiring a full protocol stack reset, thereby minimizing interruption time.
3Reliability
If detailed target cell configuration is provided to UE, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by providing specific, targeted configuration parameters (timing offset, TCI state, carrier frequency, SSB index) that are locally relevant to the target cell, rather than providing complete global configuration. This ensures communication reliability is maintained with minimal necessary information, avoiding unnecessary complexity.
Data Source
AI summary
Embodiments include methods for a user equipment (UE) configured to communicate with a radio access network (RAN) node comprising a central unit (CU) and a distributed unit (DU) that provides a serving cell for the UE. Such methods include receiving from the DU one or more lower layer signalling messages indicating that the UE should perform L1/L2-based inter-cell mobility to a first candidate cell provided by a candidate DU. The lower layer signaling message(s) include an indicator or identity of the first candidate cell and an indication of a timing offset or adjustment to be used by the UE. Such methods include performing an L1/L2 mobility procedure towards the first candidate cell and communicating in the first candidate cell based on the timing offset or adjustment. Other embodiments include complementary methods for CU, DU, and candidate DU, as well as UEs, CUs, and DUs configured to perform such methods.