Deactivated Cell PRACH Timing Advance for Faster Handover
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In wireless communications systems, there is a need to improve latency and reliability when user equipment (UE) moves between cells by enabling timing advance (TA) updates for deactivated cells, as conventional systems do not support physical random access channel (PRACH) on such cells.
Innovation Solution
Enable UE to transmit PRACH on a deactivated cell and receive a TA update, allowing for quicker communication setup and improved reliability when moving between cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional systems are used without PRACH support on deactivated cells, then device complexity is reduced and power consumption is lower, but latency increases and communication reliability deteriorates when UE moves between cells
Solution Approach 1:
The patent enables the UE to perform PRACH procedures on deactivated cells in advance, before actual handover occurs. This preliminary action allows the UE to establish timing advance and synchronize with the target cell while it is still deactivated, so that when handover is triggered, communication can resume immediately without the full setup delay, thus reducing latency while maintaining reliability
2Loss of time
If PRACH is enabled on deactivated cells for TA updates, then latency is reduced and communication reliability is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent introduces dynamic cell state management where cells can transition between activated and deactivated states based on handover requirements. The system dynamically enables PRACH functionality on deactivated cells only when needed for TA updates, and maintains the ability to deactivate them again afterward. This dynamic approach allows the system to achieve low latency when needed while avoiding permanent complexity increases
Solution Approach 2:
The patent changes the operational parameters of deactivated cells by allowing PRACH transmission and TA update reception in the deactivated state. This parameter change enables the cell to perform specific functions (timing synchronization) without being fully activated, reducing the complexity overhead of complete cell activation while still achieving the latency benefits of pre-synchronization
3Reliability
If PRACH transmission is allowed on deactivated cells, then timing advance updates are achieved and communication reliability improves, but power consumption increases
Solution Approach 1:
The patent performs PRACH transmission and TA updates as preliminary actions during the deactivated state, before the UE needs to fully activate the cell for data transmission. By completing timing synchronization in advance while the cell is still deactivated, the system reduces the power consumption that would otherwise be required for a full cell activation and subsequent synchronization procedures after handover
Data Source
AI summary
Certain aspects of the present disclosure provide techniques for updating timing advance (TA) values for deactivated cells. In an exemplary method, a user equipment receives a first command to transmit a physical random access channel (PRACH) on a first cell that is deactivated; and transmits the PRACH on the first cell in response to the first command.