Uplink Synchronization Refinement for Deactivated Cell Mobility
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Solution Overview
Problem
In wireless communications systems, timing advances for uplink transmissions to deactivated cells become inaccurate over time, leading to inefficiencies and high power consumption during inter-cell mobility, as traditional methods like random access channel procedures fail to meet low latency demands.
Innovation Solution
The network configures a UE to transmit sounding reference signals (SRS) to deactivated cells based on triggering conditions, allowing the network to decode these signals and provide updated timing advance information, ensuring accurate uplink synchronization when the cell is activated.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional random access channel procedures are used to update timing advances for deactivated cells, then the UE can obtain updated timing information, but the process consumes high power and introduces high latency
Solution Approach 1:
The patent applies preliminary action by having the UE transmit SRS signals to deactivated cells in advance before actual data transmission begins. The network decodes these SRS signals and provides timing advance updates proactively, so that when the cell is activated, the timing information is already updated and ready, eliminating the need for high-power random access procedures at the moment of activation.
Solution Approach 2:
The patent uses SRS (sounding reference signal) as an intermediary mechanism to transfer timing information. Instead of using the traditional random access channel which requires high power consumption, the SRS serves as a low-power intermediary signal that carries timing advance information from the UE to the network entity, which then uses this information to update the timing advance for the deactivated cell.
2Ease of operation
If timing advances for deactivated cells are not updated, then the UE maintains simpler operation, but uplink synchronization accuracy deteriorates over time
Solution Approach 1:
The patent implements feedback by having the network entity decode SRS signals from the UE and use this information to update timing advance values for deactivated cells. This feedback loop allows the system to maintain synchronization accuracy without requiring complex operations from the UE, as the network actively manages the timing updates based on real-time channel conditions.
Solution Approach 2:
The patent performs timing advance updates in advance before the deactivated cell is activated. By transmitting SRS signals and receiving timing advance information proactively, the system prepares updated timing parameters ahead of time, maintaining synchronization accuracy without introducing operational complexity during the actual cell activation or data transmission phases.
3Measurement precision
If the UE continuously monitors and updates timing advances for all cells, then uplink synchronization accuracy is maintained, but the device complexity and processing overhead increase
Solution Approach 1:
The patent applies partial action by having the UE transmit SRS signals only to deactivated cells that require timing advance updates, rather than continuously monitoring all cells. The network selectively decodes SRS signals and provides timing advance information only when needed, reducing processing overhead while maintaining synchronization accuracy for cells that are about to be activated.
Solution Approach 2:
The patent uses SRS signals as an intermediary that simplifies the interaction between UE and network for timing updates. Instead of the UE continuously processing and monitoring timing information for all cells, the SRS acts as a targeted intermediary that triggers timing advance updates only for deactivated cells, reducing overall processing overhead while maintaining necessary synchronization accuracy.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. The network may configure a set of cells including one or more active cells and one or more deactivated cell for a user equipment (UE). The network may indicate a triggering condition and communication resources for the UE to transmit a sounding reference signal (SRS) to the deactivated cell. Based on identifying that the triggering condition has been satisfied, the UE may transmit the SRS to the deactivated cell using the indicated communication resource. The network may decode the SRS and identify updated timing advance information. The network may indicate the updated timing advance information to the UE, and accordingly, when the deactivated cell is activated, the UE may have updated timing advance information to apply to uplink transmissions to the newly activated (previously deactivated) cell.