Terminal Handover Timing Advance Application Without Random Access
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Solution Overview
Problem
In LTE cellular communication systems, handover processes between base station cells often involve delays due to the need for random access procedures, which can be inefficient, especially when skip information is not utilized effectively for timing alignment.
Innovation Solution
A terminal apparatus that receives a handover command with skip information, applies the indicated Timing Advance (TA) value to the target primary Timing Advance Group after synchronization, and starts a Time Alignment timer, even if the skip information is later released, to facilitate efficient handover without random access procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a random access procedure is performed during handover, then timing alignment can be established, but handover delay increases
Solution Approach 1:
The base station pre-calculates and provides target TA information (targetTA) in the handover command before the terminal actually needs to perform random access. This preliminary provision of timing advance information allows the terminal to skip the random access procedure and directly apply the pre-determined timing alignment value, thus resolving the contradiction between establishing timing alignment and reducing handover delay
Solution Approach 2:
The invention extracts the timing alignment establishment step from the random access procedure by providing target TA information separately. Instead of requiring the terminal to go through the complete random access process to obtain timing alignment, the essential timing advance information is extracted and provided directly in the handover command, eliminating the need for random access while maintaining timing alignment reliability
2Productivity
If skip information (rach-Skip) is released after handover, then resource management is optimized, but timing alignment information may be lost
Solution Approach 1:
The invention creates a separate copy of the target TA information stored in the terminal's memory independently of the skip information structure. When skip information is released to optimize resources, the copied timing alignment information remains preserved in memory, preventing information loss while maintaining resource management efficiency
Solution Approach 2:
The terminal prepares and stores target TA information in advance in its memory before the skip information is released. This beforehand cushioning ensures that even if skip information is released for resource optimization, the critical timing alignment information is already safeguarded in memory and can be retrieved when needed
Data Source
AI summary
A terminal apparatus applies, in a case that a handover command is received, and the handover command includes skip information (rach-Skip) for indicating that a random access procedure for a target primary cell is skipped, a value of NTA indicated by target TA information (targetTA) included in the skip information (rach-Skip) to a target primary Timing Advance Group (TAG) after synchronization with a downlink of the target primary cell is initiated, and starts a Time Alignment (TA) timer associated with the target primary TAG.