Uplink Timing Maintenance via Predictive Advance Commands
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Solution Overview
Problem
In wireless communication systems, the absence of time alignment in uplink signals from multiple wireless devices causes significant interference due to different propagation delays, which existing methods struggle to effectively manage.
Innovation Solution
A method for controlling uplink transmission timing by applying a timing advance command based on elapsed time, speed, and distance limits, using a time alignment timer, and considering mobility status and error margins to maintain synchronization and reduce interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If timing advance commands are continuously applied to maintain uplink synchronization, then uplink timing alignment is improved, but device complexity and signaling overhead increase
Solution Approach 1:
The base station predicts the optimal timing advance value in advance based on device mobility information (speed and direction) before the time alignment timer expires. This preliminary action allows the device to resume uplink synchronization quickly without waiting for timer expiry and subsequent measurement procedures, thereby maintaining timing alignment while reducing control signaling overhead.
Solution Approach 2:
The system dynamically adjusts the timing advance command based on real-time device mobility status. By continuously monitoring speed and direction information, the base station can adaptively update timing advance values to match changing propagation conditions, maintaining reliable uplink synchronization without requiring continuous timer-based re-synchronization.
2Reliability
If timing advance commands are applied after time alignment timer expiry, then uplink synchronization is restored, but uplink transmission errors increase during the unsynchronized period
Solution Approach 1:
The base station calculates and prepares the predicted timing advance command before the time alignment timer expires. When the device requests uplink resources, the pre-calculated timing advance value is immediately applied, avoiding the period of unsynchronized transmission that would otherwise occur between timer expiry and re-synchronization.
Solution Approach 2:
The system uses feedback from device mobility measurements (speed and direction) to continuously update the predicted timing advance value. This feedback mechanism ensures that the timing advance command remains accurate even as device position changes, preventing transmission errors during the resynchronization process.
3Device complexity
If traditional timing advance methods are used without considering device mobility, then system simplicity is maintained, but timing alignment accuracy deteriorates for moving devices
Solution Approach 1:
The system introduces dynamic mobility-based adjustments to the traditional static timing advance method. By incorporating device speed and direction measurements, the timing advance command adapts to moving devices, maintaining accurate timing alignment without requiring complex multi-antenna or multi-point coordination systems.
Solution Approach 2:
The timing advance parameter is modified based on device mobility parameters (speed and direction). Instead of using a fixed or purely timer-based approach, the system changes the timing advance value according to predicted device position changes, improving timing alignment accuracy for mobile devices while keeping the overall system architecture simple.
Data Source
AI summary
Systems, apparatuses, and methods for uplink timing maintenance in wireless communications are provided. Certain aspects of the disclosure involve applying a timing advance command to adjust uplink transmission timing/resume uplink synchronization; and determining a metric. The metric can be used in determining whether to apply a timing advance command (TAC) to resume uplink resynchronization.