Inter-Cell Mobility Execution Using Preconfigured TCI States
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Solution Overview
Problem
Current inter-cell mobility in 5G networks involves lengthy latency, increased signaling overhead, and interruptions due to complete L2 and L1 resets, particularly in scenarios where the UE moves between cells served by different distributed units associated with a single centralized unit, as the UE lacks necessary information about target cell configuration to reduce interruption time.
Innovation Solution
The UE receives lower layer signaling from the serving DU indicating a target cell's TCI state, allowing L1/L2-based inter-cell mobility with reduced interruption time, and optionally includes an indication for a MAC reset when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complete L2 and L1 resets are performed during inter-cell mobility, then reliability of connection is ensured, but interruption time and latency increase significantly
Solution Approach 1:
The patent segments the mobility procedure into separate phases: preparation phase (L3 signaling for configuration) and execution phase (L1/L2 signaling for actual mobility). This allows the connection reliability to be established through L3 configuration while reducing interruption time by executing mobility through faster L1/L2 signaling without complete resets.
Solution Approach 2:
The patent applies preliminary action by performing L3 signaling in advance to configure candidate cell information and TCI states before mobility execution. This preparation allows the UE to have necessary target cell configuration ready, enabling faster execution phase with reduced interruption time while maintaining connection reliability.
2Stability of the object's composition
If complete L2 and L1 resets are performed during inter-cell mobility, then connection stability is maintained, but signaling overhead increases
Solution Approach 1:
The patent extracts the essential configuration information (TCI states, candidate cell parameters) from the complete L2/L1 reset procedure and delivers it through L3 signaling in advance. This allows connection stability to be maintained through proper configuration while reducing signaling overhead by avoiding redundant reset signaling during execution.
3Ease of operation
If the UE lacks target cell configuration information, then mobility execution can be simplified, but interruption time increases and data loss occurs
Solution Approach 1:
The patent provides target cell configuration information including TCI states through L3 signaling in the preparation phase before mobility execution. This preliminary provision of configuration information allows the execution phase to be simple and fast, reducing interruption time and preventing data loss while maintaining ease of operation.
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 a lower layer signalling message 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 includes an indicator or identity of the first candidate cell, and an indication of a first TCI state to be used by the UE for communicating with the first candidate cell. Such methods include performing) an L1/L2 mobility procedure towards the first candidate cell and communicating in the first candidate cell based on the first TCI state. Other embodiments include complementary methods for serving and candidate DUs, as well as UEs and DUs configured to perform such methods.