Uplink Timing Synchronization in LTE-A Secondary Cells
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Solution Overview
Problem
In LTE-A wireless communication systems, there is a challenge in handling PUCCH transmission for SCells when the time alignment timer expires, leading to unsynchronized uplink timing between user equipment (UE) and the network, causing interference and disrupting communication operations.
Innovation Solution
A communication device and method that establish and manage uplink time alignments with primary and secondary timing advance groups, releasing PUCCH and SRS when the secondary time alignment timer expires, and triggering a random access procedure to synchronize UL timing, ensuring proper configuration and synchronization of SCells within these groups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE continues to transmit PUCCH for SCell after the secondary TAT expires, then the communication device maintains configuration, but the uplink timing becomes unsynchronized causing interference
Solution Approach 1:
The patent extracts the harmful transmissions by releasing the PUCCH and SRS configurations for the first sTAG when the secondary TAT expires. This removes the source of interference while maintaining the primary TAT and pTAG configurations, allowing the UE to continue normal communication on the primary cell without causing uplink interference on the secondary cell.
Solution Approach 2:
The patent segments the timing advance groups into primary pTAG and secondary sTAG, with independent TATs for each. This allows the primary and secondary cells to have independent time alignment states, enabling the UE to maintain primary cell operations while releasing secondary cell transmissions when the secondary TAT expires, thus preventing interference.
2Object-generated harmful factors
If the UE releases PUCCH and SRS when secondary TAT expires, then interference is prevented, but communication operations on the first sTAG are disrupted
Solution Approach 1:
The patent segments the serving cells into different TAGs (pTAG and sTAG) with independent TATs. This allows selective release of only the first sTAG resources when its TAT expires, while preserving the pTAG and second sTAG operations. The segmented structure enables precise control over which communications continue and which are released, minimizing overall disruption.
Solution Approach 2:
The patent applies different handling policies to different TAGs based on their local state. When the secondary TAT expires, only the first sTAG (local to the expired timer) has its PUCCH and SRS released, while the pTAG and second sTAG continue operating normally. This localized approach ensures that time alignment issues in one TAG do not propagate to other TAGs.
3Loss of energy
If the network does not receive PUCCH transmission on the PUCCH SCell, then resource utilization is improved, but the network cannot detect timing synchronization status
Solution Approach 1:
The patent implements a feedback mechanism where the UE monitors its own TAT status and autonomously determines when to release PUCCH and SRS configurations. The UE sends feedback information about its timing alignment state to the network, allowing the network to understand why PUCCH transmissions may be absent without requiring continuous monitoring of every possible transmission opportunity.
Solution Approach 2:
The UE performs self-management of its timing alignment by monitoring its own TAT expiration and autonomously deciding when to release PUCCH and SRS configurations. This self-service approach eliminates the need for the network to continuously detect and measure synchronization status through various probing mechanisms, as the UE independently manages its own timing state and communicates this to the network.
Data Source
AI summary
A communication device for handling communication operations with a network comprising a storage unit and a processing means. The processing means is configured to execute instructions stored in the storage unit. The instructions comprise starting a first time alignment timer (TAT) for a pTAG comprising a PCell; starting a second TAT for a first sTAG comprising a PUCCH SCell; releasing PUCCH and SRS for all serving cell(s) of the first sTAG, when the second TAT expires and the first TAT does not expire; being configured a first SCell of the network which belongs to the pTAG or a second sTAG; being configured the first SCell which belongs to a secondary PUCCH group comprising the PUCCH SCell; and releasing PUCCH for the first SCell, when the second TAT expires and the first TAT does not expires.