Dynamic Handover Triggering for Mobile Communication Reliability
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Solution Overview
Problem
In LTE mobile communication systems, handovers are often delayed due to difficulties in real-time signal strength reporting and command transmission, leading to increased data interruption and poor communication quality, and Radio Link Failures (RLF) can occur when the target base station's signal strength is only slightly higher than the serving base station's, causing radio link failures and data interruptions.
Innovation Solution
A handover method that initiates a handover without a Time to Trigger (TTT) when the target base station's signal strength is significantly better than the serving base station's, and includes mechanisms for timely measurement reporting and RLF recovery processes, such as forcing an RLF and re-establishing a connection to the target base station if no handover command is received.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the terminal waits for TTT to expire before triggering handover, then handover stability is improved, but handover speed deteriorates causing data interruption
Solution Approach 1:
The patent dynamically adjusts the handover triggering mechanism based on signal conditions. When the serving base station's signal strength is below a reference value, the terminal immediately triggers handover without waiting for TTT to expire. When the serving signal is above the reference value, the terminal waits for TTT to expire before triggering handover. This dynamic adjustment resolves the contradiction by adapting the handover timing to current signal conditions.
Solution Approach 2:
The patent changes the handover triggering parameter (whether to wait for TTT expiration) based on the serving base station's signal strength parameter. By monitoring the signal strength and comparing it to a reference value, the system switches between two handover triggering modes: immediate triggering when signal is weak, and delayed triggering when signal is strong. This parameter-based switching resolves the contradiction between speed and stability.
2Reliability
If the terminal triggers handover only when target signal is significantly higher than serving signal, then false handovers are reduced, but handover responsiveness deteriorates
Solution Approach 1:
The patent changes the signal strength difference threshold parameter based on the serving base station's signal strength. When the serving signal is below the reference value, the terminal uses a smaller offset value (faster triggering). When the serving signal is above the reference value, the terminal uses a larger offset value (slower triggering). This dynamic parameter adjustment resolves the contradiction between accuracy and responsiveness.
3Reliability
If the terminal performs RLF recovery operations after RLF occurs, then connection reliability is improved, but communication quality deteriorates due to data interruption
Solution Approach 1:
The patent applies preliminary anti-action by preventing RLF from occurring in the first place. By monitoring the serving base station's signal strength and proactively triggering handover when the signal falls below a reference value (either immediately or after TTT expiration), the system avoids the RLF condition that would require recovery operations. This preemptive approach resolves the contradiction by eliminating the need for RLF recovery, thereby maintaining both connection reliability and communication quality.
Data Source
AI summary
A terminal starts a first timer for detecting an RLF (Radio Link Failure) when signal strength of a serving base station is lower than a reference value. The terminal triggers a handover without a TTT (Time to Trigger) for handover when signal strength of a target base station is greater than the signal strength of the serving base station by a first offset or more while the first timer is running. The terminal transmits a measurement report message regarding the signal strength of the target base station to the serving base station when a handover is triggered.