Mobility History Exchange for RRC Handover Reliability
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Solution Overview
Problem
In RRC connection re-establishment processes, target base stations lack complete mobility history information of terminal devices, leading to high handover failure probabilities due to inadequate parameter setting and cell selection.
Innovation Solution
A communication method where a first network device requests and receives mobility history information from a second network device, combining terminal and network-recorded history to accurately evaluate movement speed and select appropriate target cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the target base station relies only on current context without requesting historical mobility information, then the signaling overhead is reduced, but the handover failure probability increases due to incomplete mobility history information
Solution Approach 1:
The patent applies preliminary action by having the terminal device report mobility history information to the source base station before handover occurs. The source base station then forwards this information to the target base station in advance, ensuring the target base station has complete mobility history information available when the handover is executed, thereby improving handover reliability without increasing real-time signaling overhead.
2Measurement precision
If the source base station forwards both terminal-recorded and network-recorded mobility history information to the target base station, then the measurement parameter setting accuracy is improved, but the message size and signaling overhead increase
Solution Approach 1:
The patent applies the taking out principle by extracting and separating the two types of mobility history information (terminal-recorded and network-recorded) into distinct data elements. The source base station selectively forwards only the necessary portions of each type based on what the target base station needs for accurate movement speed evaluation, thereby reducing redundant information transmission while maintaining measurement precision.
Solution Approach 2:
The patent applies partial action by having the source base station forward only the essential mobility history information elements that are most critical for movement speed evaluation and target cell selection, rather than transmitting all possible mobility history data. This selective transmission reduces message size while still providing sufficient information for accurate handover decision-making.
3Measurement precision
If the target base station requests mobility history information from the source base station during RRC connection re-establishment, then the cell selection accuracy is improved, but the connection re-establishment time increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring the source base station with the terminal device's mobility history information before the target base station needs it during RRC connection re-establishment. When the target base station requests this information, it is already available at the source base station, allowing immediate transmission without triggering additional delays from terminal device interactions or network-wide information gathering.
4Measurement precision
If the terminal device reports mobility history information to the serving base station, then the network device can evaluate movement speed accurately, but the terminal device's processing burden and power consumption increase
Solution Approach 1:
The patent applies the copying principle by having the terminal device maintain a local copy of its mobility history information that it can report to the network. Instead of requiring the terminal to continuously query or re-collect this information, the terminal stores copies of relevant mobility data locally, enabling efficient reporting when requested by the network without significant processing burden or power consumption.
Data Source
AI summary
A method, including sending, by a first network device, to a second network device, a first message requesting a context of a terminal device from the second network device, and receiving, by the first network device, a second message from the second network device, where the second message comprises first mobility history information and second mobility history information, where the first mobility history information is recorded by the terminal device, where the second mobility history information is recorded by a network device, and where the second message is a response message of the first message.