Reference Cell Maintenance in LTE-Advanced Secondary Cells
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Solution Overview
Problem
In wireless communication systems, particularly in LTE-Advanced, reference cells may become deactivated or lose accuracy due to poor channel conditions, leading to inaccurate information references for secondary cells, which can impact uplink timing alignment and power determination.
Innovation Solution
A method for maintaining reference cells by keeping them activated when used for information reference, extending their activation time, and dynamically managing timers to prevent deactivation, along with procedures for selecting a new reference cell when the original one is lost, ensuring accurate parameter settings and timely synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a reference cell is deactivated to save UE power, then power consumption is reduced, but the accuracy of information reference for other secondary cells deteriorates
Solution Approach 1:
The patent applies preliminary anti-action by preemptively selecting a new reference cell from activated secondary cells before the original reference cell becomes deactivated or loses accuracy. This prevents the deterioration of information reference accuracy by having a backup reference ready in advance, rather than waiting for the reference cell to fail and then reacting.
Solution Approach 2:
The patent implements preliminary action by continuously monitoring the activation status and channel conditions of secondary cells, and pre-selecting a candidate reference cell that can take over if the current reference cell becomes unavailable. This ensures that the UE maintains accurate timing and pathloss references without interruption when power saving deactivation occurs.
2Productivity
If a reference cell is deactivated due to poor channel conditions, then system resources are optimized, but uplink timing alignment accuracy deteriorates
Solution Approach 1:
The patent uses an intermediary approach by introducing a selection mechanism that monitors channel conditions and activation status of multiple secondary cells. When the current reference cell experiences poor channel conditions, the intermediary selection mechanism identifies and switches to an alternative reference cell with better conditions, maintaining timing alignment accuracy without permanently deactivating resources.
Solution Approach 2:
The patent applies dynamics by making the reference cell selection flexible and adaptive rather than static. The UE dynamically evaluates channel conditions, activation states, and timing alignment quality of candidate reference cells, and switches references based on current system conditions. This allows the system to optimize resources by deactivating poor performers while maintaining accuracy through dynamic reselection.
3Measurement precision
If the deactivation timer is extended to keep reference cell activated, then information reference accuracy is maintained, but UE power consumption increases
Solution Approach 1:
The patent applies partial action by extending the deactivation timer only for the specific reference cell that needs to maintain accuracy, rather than keeping all activated cells permanently active. This selective extension maintains necessary references while allowing other non-critical cells to be deactivated for power saving, achieving a balance between accuracy and consumption.
Solution Approach 2:
The patent implements local quality by applying different activation policies to different secondary cells based on their roles. Reference cells that provide timing and pathloss information have extended timers to maintain high availability, while other secondary cells can be deactivated more aggressively for power saving. This localized differentiation optimizes the trade-off between accuracy and power consumption for each cell's specific function.
4Area of stationary object
If multiple secondary cells are configured for carrier aggregation, then bandwidth extension is achieved, but the complexity of managing multiple timing alignments increases
Solution Approach 1:
The patent applies universality by enabling any activated secondary cell to serve as a reference cell for timing and pathloss information, rather than designating fixed reference roles. This multi-functional approach allows the system to use the same pool of activated secondary cells for both data transmission and reference purposes, reducing the need for separate reference cell management and simplifying timing alignment across multiple carriers.
Data Source
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AI summary
A method of reference cell maintenance for a mobile device in a wireless communication system is disclosed the method comprises being configured a plurality of secondary cells, where one of the plurality of secondary cells is a reference cell for information reference for another secondary cell, and keeping the reference cell in activated when the reference cell is used by another secondary cell for information reference.