Conditional Handover Timer Segmentation for Access Integrity
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Solution Overview
Problem
In conditional handover (CHO) procedures, the existing timer T304 fails to guarantee the integrity of the handover mechanism due to uncertain access time by the user equipment (UE) to the target base station, leading to potential resource mismanagement and access failures.
Innovation Solution
Implementing a resource timer and an access timer in the terminal device to limit the validity of configuration/resources and access duration, respectively, ensuring that the UE only attempts handover when conditions are met and resources are available, thus preventing unnecessary access attempts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the existing timer T304 is used in conditional handover, then the timer can limit the time for UE to access target base station, but the integrity of the working mechanism cannot be guaranteed due to uncertain access time
Solution Approach 1:
The patent segments the single T304 timer into two separate timers: T304 (started when HO command is received) and T310 (started when handover is executed). This segmentation allows each timer to serve a specific function - T304 manages the handover preparation phase while T310 manages the execution phase, thereby guaranteeing the integrity of the working mechanism in conditional handover scenarios.
Solution Approach 2:
The patent introduces preliminary action by starting timer T304 when the handover command is received, before the actual handover execution. This preliminary timer ensures that resources are reserved and the handover mechanism is validated in advance, allowing the system to prepare for the uncertain access time in conditional handover while maintaining mechanism integrity.
2Reliability
If UE immediately initiates random access after receiving handover command, then resource availability can be guaranteed by timer T304, but in conditional handover the access time becomes uncertain
Solution Approach 1:
The patent introduces dynamic behavior by conditionally delaying the start of timer T310 based on whether the handover is immediate or conditional. In conditional handover, the UE monitors the target base station and only starts T310 when the handover condition is fulfilled, making the handover execution time adaptive and dynamic rather than fixed, thus resolving the contradiction between resource guarantee and uncertain access time.
Solution Approach 2:
The patent changes the parameter of timer start time from fixed (immediate upon HO command) to variable (when handover condition is fulfilled). This parameter change allows the system to maintain resource availability guarantee through T304 while accommodating the uncertain access time in conditional handover by adjusting when T310 starts based on the fulfillment of handover conditions.
3Productivity
If UE monitors configured target base station and only accesses when condition is fulfilled, then handover can be optimized, but the existing timer T304 cannot ensure resource validity
Solution Approach 1:
The patent implements feedback by having the UE monitor the target base station and evaluate handover conditions continuously. The UE provides feedback to itself about whether the handover condition is fulfilled, and only starts timer T310 and accesses the target base station when the condition is met. This feedback mechanism ensures that handover efficiency is improved through conditional monitoring while resource validity is maintained through the coordinated operation of T304 and T310 timers.
Data Source
AI summary
An embodiment of the present disclosure relates to a handover method between network devices and a network device. The method includes: sending, by a network device, at least one handover command corresponding to a plurality of target network devices to a terminal device. The at least one handover command corresponding to the plurality of target network devices includes a first handover command, and the first handover command includes configuration information of a first target network device among the plurality of target network devices, so that the terminal device starts a first access timer corresponding to the first target network device in response to that the terminal device determines to establish a connection with the first target network device. The terminal device establishes a connection with the first target network device according to the first access timer.