Antenna Gain-Based NTN Handover Using Coverage Boundaries
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Solution Overview
Problem
Existing handover procedures in Non-Terrestrial Networks (NTN) based on UE measurements lead to increased mobility events and service failures due to high satellite movement, necessitating improved triggering criteria to reduce signaling load and enhance mobility performance.
Innovation Solution
Utilizing antenna gain patterns to determine coverage boundaries between satellite cells, enabling UE to trigger handovers based on predicted satellite trajectories and radio propagation conditions, or allowing the network to initiate handovers based on accurate UE positioning and outdated location checks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional handover procedures based on UE measurements are used in NTN, then handover decisions can be made, but the number of mobility events increases and service failures occur due to high satellite movement
Solution Approach 1:
The network performs preliminary calculations of coverage boundaries and handover triggering criteria based on satellite trajectories and antenna gain patterns before handover is needed. This allows the network to predict optimal handover points in advance, reducing the number of mobility events while maintaining service continuity.
Solution Approach 2:
The patent introduces coverage boundary information and antenna gain patterns as intermediary elements between the satellite and UE. These intermediaries carry predictive information about signal conditions, allowing handover decisions to be made based on pre-calculated data rather than real-time measurements, thereby reducing mobility events.
2Reliability
If UE measurements are used for handover triggering, then handover decisions can be made, but signaling overhead increases
Solution Approach 1:
The patent uses coverage boundary information and antenna gain patterns as intermediaries to convey handover triggering criteria from the network to the UE. This reduces signaling overhead by providing predictive information that eliminates the need for continuous measurement reports and handover-related signaling exchanges.
Solution Approach 2:
The UE uses the provided coverage boundary information and antenna gain patterns to autonomously determine handover triggering criteria without requiring continuous network signaling. This self-service approach reduces signaling overhead while maintaining accurate handover decisions.
3Reliability
If handover is triggered based on real-time measurements, then service continuity can be maintained, but late handovers occur due to satellite movement
Solution Approach 1:
The network performs preliminary calculations of coverage boundaries and handover triggering criteria based on satellite trajectories and antenna gain patterns before handover is needed. This advance preparation allows the UE to trigger handovers at optimal times, avoiding late handovers while maintaining service continuity.
Solution Approach 2:
The patent dynamically adapts handover triggering criteria based on satellite movement characteristics and antenna gain patterns. By continuously updating coverage boundary information based on predicted satellite positions, the system maintains accurate handover timing despite the dynamic nature of NTN environments.
Data Source
AI summary
Method comprising:receiving, from a first cell of a satellite, a handover command triggering a handover of a terminal from the first cell of the satellite to a second cell of the satellite and an assumed location of the terminal;determining an actual location of the terminal;checking one or more of the following conditions applies: the actual location of the terminal deviates from the assumed location by more than a first threshold, and the actual location of the terminal is on the side of the first cell of the coverage boundary and remote from the coverage boundary by at least a second threshold;preventing the terminal from performing the handover if at least one of the one or more checked conditions is fulfilled.