Mobility Robustness via Combined Handover and Radio Link Failure Timers
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Solution Overview
Problem
Cellular networks face challenges in maintaining robust mobility functions, particularly during handovers, due to issues like premature or late handovers, leading to radio link failures and disruptions in service.
Innovation Solution
A method is introduced to enhance mobility robustness by adjusting handover parameters based on combined information from handover and radio link failure procedures, using timers like T312 to detect and respond to radio link failures more effectively, and optimizing parameters dynamically to prevent service interruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If handover parameters are adjusted dynamically based on combined information from handover and radio link failure procedures, then mobility robustness is improved, but system complexity increases
Solution Approach 1:
The patent combines information from handover procedures and radio link failure procedures into a unified mobility robustness optimization mechanism. The network entity integrates handover failure information, radio link failure information, and mobility information from multiple sources to adjust handover parameters dynamically, creating a comprehensive mobility management system that improves reliability while managing complexity through systematic integration.
Solution Approach 2:
The patent implements a feedback mechanism where the network entity continuously monitors handover performance and radio link failure events, then uses this information to adjust handover parameters. The system receives feedback about mobility robustness issues and dynamically modifies parameters such as handover thresholds and timing to optimize performance, creating a closed-loop control system that adapts to changing network conditions.
2Speed
If timers like T312 are used to detect radio link failures more quickly, then failure detection speed is improved, but risk of premature handovers increases
Solution Approach 1:
The patent uses timer T312 to start monitoring for radio link failure conditions in advance, before actual failure occurs. The timer provides a head start for detecting degradation in radio link quality, allowing the network to prepare for potential handover needs while still having accurate information about the actual failure state when the timer expires or is stopped.
Solution Approach 2:
The patent dynamically adjusts the behavior of timer T312 based on network conditions and handover context. The timer can be started, stopped, or reset depending on whether handover is in progress, whether radio link quality is degrading, or whether recovery has occurred. This dynamic timing mechanism allows fast failure detection while preventing premature handovers by adapting the timer behavior to the actual system state.
Data Source
AI summary
A user equipment starts a first timer and a second timer in response to different respective network events. The starting of the first and second timers causes the first and second timers to simultaneously elapse. In response to one of the simultaneously elapsing timers expiring, the user equipment indicates, to a network node, which of the simultaneously elapsing timers expired.