Packet Data Drop Mechanism for Handover Delay Reduction
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Solution Overview
Problem
During handover in mobile communication systems, transmission delays and packet data loss occur due to interruptions, which increase overall transmission time and delay, and existing methods do not effectively mitigate these issues.
Innovation Solution
The implementation of a combined timer-based and Active Queue Management (AQM)-based packet data drop mechanism in the PDCP layer of user equipment and base stations, where packet data is dropped based on drop timers and AQM techniques to minimize transmission interruptions and optimize data transfer during handover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If hard handover is used to achieve fast handover, then handover speed is improved, but transmission interruption time increases and packet data loss occurs
Solution Approach 1:
The patent applies preliminary action by starting the drop timer before handover occurs and maintaining it during handover. The timer is initialized with a value that accounts for the upcoming transmission interruption, allowing packet data to be dropped proactively rather than reactively after interruption has already caused loss. This preliminary timing mechanism enables the system to prepare for and mitigate the transmission interruption effects.
Solution Approach 2:
The patent changes the parameter of packet data handling by introducing a drop timer that dynamically adjusts the behavior of packet data during handover. Instead of maintaining all packet data during interruption, the timer parameter controls when packet data should be dropped, transforming the static buffering approach into a dynamic parameter-based decision system that adapts to handover timing.
2Reliability
If packet data is maintained during handover to prevent loss, then packet data reliability is improved, but transmission delay increases
Solution Approach 1:
The patent implements feedback by continuously monitoring the drop timer value and using it to determine when packet data should be dropped. The timer provides feedback about the elapsed time since handover initiation, allowing the system to adaptively decide whether to maintain or drop packet data based on real-time timing information rather than static rules.
Solution Approach 2:
The patent uses parameter changes by dynamically adjusting the packet data retention decision based on the drop timer parameter. As the timer value changes during handover, the system transitions from maintaining packet data (when timer value is high) to dropping packet data (when timer value expires), optimizing the balance between reliability and delay through parameter-driven control.
3Loss of time
If packet data is dropped during handover to reduce delay, then transmission delay is improved, but packet data loss increases
Solution Approach 1:
The patent applies preliminary action by initializing the drop timer before handover and maintaining it throughout the handover process. This preliminary timing setup ensures that packet data is dropped at the optimal moment - after the handover has completed and transmission has resumed - rather than during the critical handover transition, thus preventing unnecessary packet loss while still reducing delay.
Solution Approach 2:
The patent uses feedback from the drop timer to make intelligent decisions about packet data retention. The timer provides continuous feedback on handover progress and transmission status, allowing the system to drop packet data only when safe (after handover completion) rather than arbitrarily during handover, thus balancing delay reduction with reliability preservation.
Data Source
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AI summary
A control method in a mobile communication system, the control method comprising: configuring a discard timer corresponding to a service data unit (SDU) for discarding the SDU according to a value of the timer; maintaining the value of the discard timer corresponding to the SDU when a handover is performed without restarting or resetting the value of the discard timer; and discarding the corresponding SDU when the maintained value of the discard timer reaches a given value.