LTM Cell Switching Without PTAG Timing Advance Values
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Solution Overview
Problem
Existing wireless communication systems face challenges in handling layer 1 or layer 2 triggered mobility (LTM) cell switch commands without timing adjustment values for primary timing advance groups (PTAG), leading to inefficiencies in timing alignment during cell switching.
Innovation Solution
A method for wireless devices and base stations that involves receiving an LTM cell switch command without a timing adjustment value, initiating a time alignment timer after measuring the cell's timing advance, and adjusting timing accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the LTM cell switch command does not include a timing adjustment value for PTAG, then the command structure is simplified and processing is faster, but timing alignment during cell switching becomes problematic
Solution Approach 1:
The patent applies preliminary action by having the wireless device measure the timing advance of the target cell before completing the cell switch command processing. The device starts the time alignment timer and measures the timing advance in advance, so that when the cell switch is executed, the timing alignment is already prepared, resolving the contradiction between fast switching and reliable timing alignment.
2Reliability
If the time alignment timer is started after measuring timing advance, then timing alignment is achieved, but the cell switching process becomes more complex
Solution Approach 1:
The patent applies self-service by enabling the wireless device to autonomously measure the timing advance and start the time alignment timer without requiring explicit network control for each step. The device independently handles the timing alignment process after receiving the cell switch command, reducing the complexity of network-side control while maintaining reliable timing alignment.
Data Source
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Figure 3
AI summary
A method may include receiving, by a wireless device, a layer (1) or layer (2) triggered mobility (LTM) cell switch command. The LTM cell switch command may include a configuration index indicating a cell for an LTM procedure. The LTM cell switch command may omit a timing adjustment value for a primary timing advance group (PTAG) of the cell. For example, there may be no timing adjustment value for the PTAG of the cell included in or with the LTM cell switch command. In response to receiving the LTM cell switch command with no timing adjustment value, the wireless device may start a time alignment timer associated with the PTAG after measuring a timing advance of the cell.