UE Mobility Timing Alignment Between NTN and TN Cells
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Solution Overview
Problem
Existing wireless communication systems face challenges in managing seamless mobility between non-terrestrial networks (NTN) and terrestrial networks (TN) due to timing misalignment and inefficiencies in measurement gap configurations, leading to reduced reliability and increased latency.
Innovation Solution
The use of an absolute timing reference timestamp from a terrestrial network entity to configure measurement gaps for user equipment (UE) to switch between NTN and TN cells, thereby improving synchronization and reducing signaling overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If measurement gap configurations are used for UE mobility between NTN and TN cells, then cell measurement procedures can be performed, but timing misalignment occurs leading to reduced reliability and increased latency
Solution Approach 1:
The patent changes the timing reference parameter from NTN-based timing to TN-based absolute timing reference. The network entity configures the UE with a measurement gap based on an absolute timing reference from the TN cell, allowing synchronized measurement without timing misalignment. This parameter change resolves the contradiction by eliminating the timing reference mismatch between NTN and TN cells.
2Adaptability or versatility
If measurement gaps are configured based on NTN timing reference, then UE can monitor TN cells, but timing misalignment with TN cell transmissions occurs
Solution Approach 1:
The patent introduces the TN cell's absolute timing reference as an intermediary for configuring measurement gaps. Instead of using NTN timing reference directly, the network entity uses TN timing as the intermediary reference point, allowing the UE to align its measurement gap with TN cell transmissions. This intermediary timing reference resolves the measurement precision issue while maintaining adaptability.
3Adaptability or versatility
If UE performs cell measurement procedures for both NTN and TN cells, then mobility options are maintained, but signaling overhead increases
Solution Approach 1:
The patent segments the measurement procedure into two distinct parts: NTN cell measurements continue with existing NTN timing references, while TN cell measurements use a separate configuration based on TN absolute timing reference. This segmentation allows independent optimization of each measurement type, reducing the complexity of managing unified timing across heterogeneous networks while maintaining both mobility options.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. In some systems, a user equipment (UE) may support mobility between a non-terrestrial network (NTN) cell and a terrestrial network (TN) cell. If the UE is connected to an NTN cell, the UE may determine timing for a neighboring TN cell using a reference timestamp. A first network entity supporting the NTN cell may request the reference timestamp from a second network entity supporting the TN cell. The second network entity may output the timestamp in response to the request. The first network entity may obtain the timestamp and output an indication of the timestamp to the UE in a measurement gap configuration. The UE may use the reference timestamp to determine timing for a measurement gap and may monitor for a signal (e.g., a synchronization signal) from the second network entity supporting the TN cell during the measurement gap.