Cell Handover Time Windows to Prevent Target Cell Congestion
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Solution Overview
Problem
In non-terrestrial network (NTN) systems, the issue of how a terminal device executes a cell handover when the handover command is received in advance is not adequately addressed, leading to potential congestion when multiple devices attempt to connect to a target cell simultaneously.
Innovation Solution
A cell handover method where a terminal device determines a first time window for establishing a connection with a target cell based on a handover command, allowing flexible execution of the handover within this window to avoid centralized access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the source network device determines the target cell in advance and sends an advance handover command to avoid transmitting a large number of handover commands in a short period, then the signaling overhead is reduced, but the terminal devices may attempt to connect to the target cell simultaneously causing congestion
Solution Approach 1:
The source network device determines the target cell in advance and sends the handover command before the terminal device needs to switch cells. This preliminary action reduces signaling overhead by avoiding multiple handover commands, while the time window mechanism ensures devices don't connect simultaneously to the target cell, preventing congestion.
Solution Approach 2:
The patent introduces a dynamic time window mechanism that allows terminal devices to flexibly select when to execute the handover within a specified duration. This dynamic approach distributes connection attempts over time, preventing simultaneous access to the target cell while maintaining the advance handover command benefits.
2Speed
If terminal devices execute handover immediately upon receiving the handover command, then the handover speed is improved, but congestion occurs at the target cell due to simultaneous access
Solution Approach 1:
The patent implements periodic action by distributing handover executions across a time window rather than all at once. Terminal devices execute handovers at different times within the specified window, maintaining fast handover speeds while preventing target cell congestion through temporal distribution of access attempts.
3Ease of operation
If a fixed handover timing is specified in the handover command, then the handover execution is simplified, but it cannot adapt to varying network conditions and device states
Solution Approach 1:
The patent segments the handover execution into two parts: the network device specifies a time window (simplified configuration), while the terminal device independently selects the exact execution timing within that window (adapted to device state). This segmentation maintains ease of operation while improving adaptability to varying conditions.
Solution Approach 2:
The terminal device autonomously determines the precise handover execution timing within the network-specified window based on its own state and conditions. This self-service approach simplifies network control while enabling each device to adapt to its specific situation, balancing ease of operation with flexibility.
Data Source
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AI summary
The present application provides a cell handover method, a terminal device and a network device, which help to avoid the congestion caused by a large number of terminal devices accessing a target cell in a centralized manner. The method comprises: receiving, by a terminal device, a handover command sent by a source network device, wherein the handover command is configured to indicate that the terminal device can switch from a source cell corresponding to the source network device to a first time window of a target cell corresponding to a target network device; and performing, by the terminal device, cell handover according to the first time window.