LTE Handover Coordination for High-Speed User Equipment
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Solution Overview
Problem
High-speed user equipment (UE) experiences call drops and handover failures in LTE networks due to incorrect speed estimation, degraded channel conditions, and insufficient time for measurement reporting, especially when moving from one cell to another.
Innovation Solution
Implementing a method where the source base station measures the speed of the UE and estimates channel quality based on channel quality index reports, signaling candidate base stations to coordinate with the source base station for transmitting a handover command, and adjusting handover parameters to accommodate high-speed UEs, including coordinating with multiple network nodes to ensure successful handover command delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If regular handover procedure is used for high-speed UE, then handover can be performed with standard protocol, but handover fails due to incorrect speed estimation and degraded channel conditions
Solution Approach 1:
The patent implements dynamic handover parameter adjustment based on detected UE speed. The source eNB determines UE speed by analyzing measurement report timing and adjusts handover parameters dynamically according to speed thresholds. This allows the system to adapt handover behavior to the UE's movement state, improving reliability for high-speed UEs while maintaining standard operation for normal-speed UEs.
Solution Approach 2:
The patent changes handover parameters based on UE speed classification. When UE speed exceeds a threshold, the system modifies parameters such as handover triggering offsets and measurement timing to accommodate high-speed movement. This parameter adaptation resolves the contradiction by making the handover procedure versatile enough for different speed conditions while maintaining reliability through condition-specific optimization.
2Reliability
If handover command is transmitted to high-speed UE, then handover can be initiated, but UE may fail to receive or decode the command due to degraded channel conditions
Solution Approach 1:
The patent performs preliminary actions to ensure handover command delivery before the UE moves out of coverage. The source eNB determines an offset based on UE speed and transmits the handover command earlier than in standard procedures. This preliminary timing adjustment compensates for the UE's high-speed movement and channel degradation, ensuring the command is received and decoded successfully.
Solution Approach 2:
The patent uses feedback from measurement reports to adjust handover command transmission timing. The source eNB analyzes the timing of measurement reports to detect high-speed movement and uses this feedback to calculate appropriate offsets for handover command transmission. This closed-loop feedback mechanism improves reliability by adapting to actual channel conditions caused by UE speed.
3Productivity
If UE reports measurement results at regular intervals, then measurement reporting follows standard protocol, but UE has insufficient time to report before moving out of serving cell
Solution Approach 1:
The patent dynamically adjusts measurement reporting timing based on UE speed. The source eNB determines UE speed from measurement report patterns and adjusts the timing of handover-related measurements and reporting accordingly. For high-speed UEs, the system reduces the time interval for critical measurements, ensuring measurements are completed and reported before the UE moves out of serving cell coverage.
Solution Approach 2:
The patent changes measurement timing parameters based on detected UE speed. When high speed is detected, the system modifies parameters such as measurement timing offsets and reporting deadlines to provide sufficient time for measurement and reporting. This parameter adaptation resolves the contradiction by maintaining productivity through faster handover execution while preventing time loss through accelerated measurement timing for high-speed UEs.
Data Source
AI summary
Methods and apparatus are disclosed for handing over of a high-speed mobile terminal or user equipment from a source network node to a target network node. Reliable methods for measuring the speed of a moving user equipment are disclosed. Parameters used in a handover procedure are also adjusted in accordance with the speed of the user equipment. For handing over a high-speed user equipment, the present application discloses that the source network node can coordinate with the target network node and other candidate network nodes in transmitting a handover command to prevent handover failures.