UE Handover Offset Time and Area Configuration in Non-Terrestrial Networks
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Solution Overview
Problem
In non-terrestrial networks (NTNs), the handover procedure for user equipment (UE) is challenging due to the rapid change of satellite coverage, leading to significant signaling load and random access collision, which affects the success rate of handovers and power efficiency.
Innovation Solution
A method for performing a handover procedure in UEs, which involves receiving a handover command from the network, including parameters such as offset time and configured area, to optimize the handover timing and location, thereby reducing signaling overhead and random access collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all connected UEs perform handover simultaneously when satellite changes, then handover completion is achieved, but signaling load increases significantly
Solution Approach 1:
The network pre-configures handover commands for multiple target satellites before the actual handover occurs. UEs store these pre-configured commands and execute them when triggered, avoiding the need to process handover commands in real-time during satellite transitions, thereby reducing signaling load while ensuring reliable handover completion.
Solution Approach 2:
The patent implements dynamic handover execution where UEs do not execute handovers simultaneously but rather at different times based on individual conditions. The network can trigger handovers dynamically based on UE location, satellite visibility, and network load, spreading out the signaling traffic over time while still achieving complete handover for all UEs.
2Speed
If handover is performed quickly to maintain connectivity, then service continuity is improved, but random access collision increases due to limited contention-free resources
Solution Approach 1:
The patent segments the handover process into multiple phases: preparation phase where handover commands are pre-configured, execution phase where UEs actually perform handover, and recovery phase for handling failures. This segmentation allows the system to maintain fast handover speed while managing random access collisions through dedicated resources in each phase.
Solution Approach 2:
The network introduces an intermediary mechanism using pre-configured handover commands that contain dedicated random access resources. Instead of UEs competing for limited contention-free resources during handover, the network mediates by assigning specific resources in advance, ensuring both fast handover execution and high random access success rate.
3Measurement precision
If UEs perform frequent measurements to track satellite movement, then handover timing accuracy is improved, but power consumption increases
Solution Approach 1:
The network provides pre-configured handover commands containing target satellite information and execution conditions before UEs need to perform measurements. UEs can use this advance information to reduce the frequency and intensity of measurements, achieving sufficient handover timing accuracy with lower power consumption by only measuring when conditions change significantly.
Data Source
AI summary
A method for a user equipment (UE) performing a handover procedure is disclosed. The method includes receiving a handover command from a network, in a case that a first information related to an offset time is included in the handover command, performing the handover procedure based on the handover command after the offset time, and in a case that a second information related to a configured area is included in the handover command, performing the handover procedure based on the handover command when the UE locating within the configured area.