Timing Advance Mapping for Accurate Mobility Cell Switching
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Solution Overview
Problem
Inaccurate timing advance acquisition during L1 and/or L2 triggered mobility (LTM) switch leads to unsuccessful cell switching due to ambiguous mapping of terminal devices to timing advances, causing synchronization issues and interruptions.
Innovation Solution
A method where network devices exchange identification and time-frequency position information of random access preambles to accurately associate timing advances with specific terminal devices, ensuring precise synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple terminal devices send random access preambles to the target DU, then the target DU can obtain timing advances through calculation, but the source DU cannot determine which terminal device corresponds to which timing advance, resulting in inaccurate TA assignment
Solution Approach 1:
The target DU feeds back identification information of terminal devices along with the calculated timing advances to the source DU. This feedback mechanism enables the source DU to correctly match each terminal device with its corresponding timing advance, resolving the ambiguity problem while maintaining timing advance accuracy.
Solution Approach 2:
The target DU acts as an intermediary that receives random access preambles from terminal devices, calculates timing advances, and then forwards both the timing advances and associated identification information to the source DU. This intermediary role ensures proper mapping between terminal devices and timing advances is established.
2Measurement precision
If the target DU sends timing advances to the source DU through the CU, then the CU cannot determine which source DU corresponds to which timing advance, causing inaccurate TA delivery to terminal devices
Solution Approach 1:
The target DU includes identification information of the source DU in the feedback message sent to the source DU via the CU. This feedback contains both the timing advance and the identifier of the corresponding source DU, enabling correct routing and assignment while maintaining accuracy.
Solution Approach 2:
The target DU serves as an intermediary that properly associates timing advances with source DU identifiers before forwarding them through the CU. This ensures that even though the CU relays the message, the mapping information is preserved and accurate TA delivery is achieved.
3Reliability
If the source DU sends the switch command or downlink message carrying the TA to the terminal device, then uplink synchronization can be achieved, but the process requires accurate TA assignment which is compromised by the ambiguous mapping problem
Solution Approach 1:
The feedback mechanism from the target DU to the source DU, which includes terminal device identification information, ensures that the source DU has accurate mapping information before sending the switch command or downlink message with TA to the terminal device, thereby ensuring both reliability and precision.
Solution Approach 2:
The target DU performs preliminary calculation of timing advances and prepares the mapping information before the source DU sends the switch command. This preliminary action ensures that accurate TA assignment is ready in advance, enabling reliable cell switching without ambiguity.
Data Source
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AI summary
This application provides a timing advance acquisition method and an apparatus. The method includes: A first network device receives a first message from a second network device, where the first message indicates a first TA and includes first information, and the first information includes one or more of the following: identification information of a first random access preamble and information about a first time-frequency position; identification information of a first terminal device; or the identification information of the first random access preamble, the information about the first time-frequency position, and the identification information of the first terminal device; and the first network device sends the first TA to the first terminal device based on the first information. In the method, the first network device may determine, based on information about a terminal device corresponding to the first TA, that the first TA corresponds to the first terminal device, and send the first TA to the first terminal device, to improve accuracy of the TA obtained by the terminal device.