Secondary Cell Deactivation Timer Control in LTE Carrier Aggregation
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Solution Overview
Problem
In wireless communication systems, particularly in LTE, the deactivation timer of secondary cells can unexpectedly expire, leading to interference issues due to invalid uplink timing advances, especially when secondary serving cells are deactivated without proper management.
Innovation Solution
A method and apparatus for controlling the deactivation timer of secondary cells by configuring a secondary timing advance group (sTAG) with an infinite time value or disabling the deactivation timer based on indicators received via RRC or MAC signaling, ensuring the secondary cell maintains an activation state and preventing premature deactivation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the deactivation timer is enabled for secondary cells, then the system can automatically deactivate inactive cells to save resources, but the timer may expire prematurely causing interference due to invalid uplink timing advances
Solution Approach 1:
The patent applies preliminary anti-action by disabling the deactivation timer before it can expire and cause interference. When a secondary cell is configured with RACH parameters or receives a PDCCH order for random access, the timer is proactively disabled to prevent the harmful event (timer expiration leading to invalid timing advance) from occurring in the first place
Solution Approach 2:
The patent implements preliminary action by preparing the secondary cell for potential activation through random access procedures before the deactivation timer expires. By configuring RACH parameters in advance and potentially initiating random access, the system ensures timing advance validity is maintained or re-established before the timer would cause deactivation
2Reliability
If the deactivation timer is disabled for secondary cells, then uplink timing advance validity is maintained, but the system cannot automatically deactivate inactive cells to save resources
Solution Approach 1:
The patent applies local quality by selectively disabling the deactivation timer only for specific secondary cells that require it (those configured with RACH parameters or receiving PDCCH orders), rather than disabling it system-wide. This allows the system to maintain reliability where needed while preserving resource savings for other cells
Solution Approach 2:
The patent implements dynamics by making the deactivation timer state configurable and changeable based on operational conditions. The timer can be enabled or disabled dynamically depending on whether the cell is configured for random access, allowing the system to adapt resource management behavior to actual needs
3Reliability
If random access is performed on secondary cells to maintain timing advance, then timing advance validity is ensured, but additional signaling overhead and complexity are introduced
Solution Approach 1:
The patent applies preliminary action by pre-configuring RACH parameters for secondary cells during initial setup. This preparation allows random access to be performed quickly and efficiently when needed, reducing the actual signaling overhead during operation while ensuring timing advance validity can be maintained
Data Source
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AI summary
The present specification proposes a technique for controlling a deactivation timer of a cell. Specifically, the present specification proposes a method for controlling a deactivation timer of a cell in a mobile communication system. The method comprises the steps of: configuring a primary cell and at least one secondary cell on user equipment (UE); receiving, from the UE, an indicator related to a deactivation timer for one secondary cell from among one or more secondary cells; and disabling, on the UE, the deactivation timer of one secondary cell on the basis of the indicator.