Uplink Signal Transmission Across Unlicensed Component Carriers
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Solution Overview
Problem
In wireless communication systems, when multiple unlicensed component carriers belong to different Timing Advance Groups (TAGs), existing methods face challenges in preventing signal transmission blocking and ensuring efficient channel access for uplink signals, particularly due to nonideal backhaul connections and differing UL timings across U-cells.
Innovation Solution
A method and apparatus for transmitting uplink signals in a wireless communication system that employs a Listen Before Talk (LBT) procedure and configures Physical Downlink Control Channel (PDCCH) search spaces to enable efficient channel access and prevent signal blocking across unlicensed component carriers, even when they belong to different TAGs, by adjusting transmission start points and using specific LBT parameters and PDCCH search space configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple unlicensed component carriers are connected through nonideal backhaul, then carrier aggregation capability is improved, but signal transmission blocking occurs due to different UL timings
Solution Approach 1:
The system segments unlicensed component carriers into different Timing Advance Groups (TAGs) based on their backhaul connection characteristics. Carriers connected through ideal backhaul form one TAG, while those connected through nonideal backhaul form another TAG. This segmentation allows independent timing management for each group, preventing signal transmission blocking while maintaining carrier aggregation capability.
Solution Approach 2:
The system performs preliminary configuration of TAG assignments and timing advance values before uplink transmission begins. By pre-establishing the timing relationships and grouping carriers appropriately, the system avoids dynamic timing conflicts that would cause signal blocking during actual transmission.
2Productivity
If Listen Before Talk (LBT) procedure is implemented on unlicensed carriers, then channel access efficiency is improved, but transmission start point alignment becomes complex across different TAGs
Solution Approach 1:
The system applies different timing advance configurations to different TAGs based on their local characteristics. Each TAG has its own timing advance value optimized for its specific backhaul conditions, allowing LBT to be performed efficiently within each group while managing alignment complexity through localized rather than uniform configuration.
3Reliability
If different Timing Advance Groups are used for unlicensed carriers, then signal blocking is prevented, but channel access coordination becomes more complex
Solution Approach 1:
The system implements feedback mechanisms where the base station monitors uplink transmission timing and channel access status from different TAGs. Based on this feedback, the base station adjusts timing advance values and coordinates LBT parameters to maintain reliable transmission while managing coordination complexity through adaptive control.
Data Source
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AI summary
The present invention provides a method for transmitting an uplink signal to a base station by a terminal in a wireless communication system supporting an unlicensed band, and a device supporting the same. More particularly, the present invention provides a method for transmitting an uplink signal through an LBT method of a terminal and a plurality of unlicensed component carriers on the basis of the LBT method when two or more unlicensed component carriers among the plurality of unlicensed component carriers are included in different timing advance groups (TAGs) in a wireless communication system supporting the plurality of unlicensed component carriers, and a device supporting the same.