Conditional Handover Time Window Control for XR Reliability
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Solution Overview
Problem
Current handover procedures in cellular networks often result in negative impacts on transmission quality due to improper timing, leading to radio link failures and handover failures, especially in scenarios requiring high data rates and low latency like extended reality services.
Innovation Solution
An enhanced handover procedure is implemented, where the network determines specific time windows during which no downlink or uplink user plane data is expected, and communicates these windows to the terminal device, allowing it to initiate a handover only when certain conditions are met within these time frames, thereby decoupling handover execution from preparation and ensuring it does not collide with data transmission periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If handover is initiated without time window restrictions, then handover execution is simple and fast, but transmission quality deteriorates due to collisions with data transmission periods
Solution Approach 1:
The network pre-configures time window information and handover conditions to the terminal device before actual handover execution. The terminal device evaluates whether current time falls within allowed handover time windows and whether handover conditions are met, ensuring handover only occurs during appropriate periods without colliding with data transmission, thus improving transmission quality while maintaining procedural simplicity
Solution Approach 2:
The handover procedure incorporates dynamic time window evaluation where the terminal device continuously monitors whether the current time falls within pre-configured handover time windows. This dynamic timing control allows handover to be executed only during appropriate periods when data transmission is not occurring, resolving the contradiction between simple handover execution and transmission quality maintenance
2Reliability
If handover timing is controlled to avoid data transmission periods, then radio link failures are reduced, but handover execution timing becomes more complex
Solution Approach 1:
The network provides pre-configured time window information and handover conditions to the terminal device in advance. The terminal device autonomously evaluates whether current time and conditions meet handover requirements, enabling rapid handover execution during appropriate time windows without requiring real-time network coordination, thus improving mobility robustness while minimizing timing delays
Solution Approach 2:
The terminal device performs autonomous evaluation of handover conditions and time window compliance without continuous network intervention. The device independently determines whether to execute handover based on pre-configured parameters and current state, reducing handover timing complexity and execution delay while maintaining high mobility robustness
3Speed
If handover is executed during data transmission periods, then handover latency is reduced, but transmission quality and data rate are negatively impacted
Solution Approach 1:
The network pre-configures multiple time windows and corresponding handover conditions to the terminal device. The terminal device evaluates whether current time falls within any of the configured time windows and whether handover conditions are met, enabling fast handover execution during appropriate periods without colliding with data transmission, thus maintaining both low latency and high service quality
Solution Approach 2:
The handover mechanism uses periodic time windows where handover execution is permitted only during specific intervals. This periodic structure allows handover to occur at predictable, appropriate moments when data transmission is not occurring, maintaining fast execution speed while preserving transmission quality and service reliability
Data Source
AI summary
Disclosed is a method comprising receiving an indication indicating one or more time windows, during which a handover is allowed to be initiated; evaluating whether one or more conditions for the handover are fulfilled within the one or more time windows; and initiating the handover during one of the one or more time windows, if the one or more conditions are fulfilled.