Conditional Cell Handover Using Lower-Layer Signaling and Early TA
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing cell handover procedures in wireless communications systems face issues such as longer latency and overhead due to higher-layer signaling, and challenges in managing timing advance (TA) acquisition and candidate cell prioritization during conditional handovers.
Innovation Solution
Implementing a conditional handover procedure using lower-layer signaling, where UEs initiate handovers based on timer-based execution conditions and early TA procedures, allowing for faster and more efficient handover decisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If higher-layer signaling is used for cell handover, then handover decision accuracy is improved, but latency and overhead increase
Solution Approach 1:
The patent applies preliminary action by pre-configuring handover parameters, candidate cell lists, and execution conditions through RRC signaling before the handover event occurs. The UE prepares measurement configurations, reporting criteria, and handover execution thresholds in advance, so that when handover is needed, the decision can be made quickly using pre-prepared information rather than negotiating parameters in real-time
Solution Approach 2:
The patent introduces an intermediary mechanism by using pre-configured measurement configurations and reporting rules as intermediaries between the network's handover decisions and the UE's execution. The RRC-configured parameters act as a intermediary layer that translates network intent into UE actions, reducing the need for real-time higher-layer signaling during the actual handover event
2Reliability
If conditional handover with multiple candidate cells is implemented, then handover reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the handover process into distinct phases: measurement configuration, condition evaluation, and execution. Each candidate cell is evaluated independently against predefined conditions, and the handover execution is segmented into specific triggering events. This modular approach manages complexity by breaking down the complex multi-cell handover decision into manageable, independent evaluation units
Solution Approach 2:
The patent uses parameter changes by dynamically adjusting measurement thresholds, reporting configurations, and execution conditions based on the specific handover scenario. The network can modify measurement objectives, threshold values, and condition parameters to optimize the balance between reliability and complexity for different deployment scenarios and UE capabilities
3Speed
If early TA procedure is initiated, then handover speed is improved, but timing synchronization difficulty increases
Solution Approach 1:
The patent applies preliminary action by initiating the timing advance procedure before the actual handover execution. The UE performs early TA measurement and reporting to the network, allowing the network to prepare and provide TA commands in advance. This preliminary TA acquisition reduces the time needed for synchronization at the moment of handover execution
Solution Approach 2:
The patent implements feedback mechanisms where the UE reports early TA measurements and timing information back to the network. The network uses this feedback to adjust and optimize TA commands, providing continuous refinement of timing synchronization information as the handover process unfolds, thereby managing synchronization difficulty through iterative feedback
Data Source
AI summary
Various aspects of the present disclosure relate to conditional execution of cell handover. The techniques discussed herein describe conditional handover using lower-layered signaling (e.g., L1 or L2). In one or more implementations, the UE starts a timer, which may have been configured earlier in a conditional configuration message (also referred to herein as a conditional reconfiguration message) received from a network equipment. If a timing advance (TA) value for a first candidate cell is received before the expiry of this timer, the UE transmits handover completion to the first candidate cell. However, if a TA value for the first candidate cell is received after the expiry of this timer, the UE considers the one or more conditions for the first candidate cell as not fulfilled and may invalidate the TA value and start a fresh evaluation or measurement of the one or more conditions.