HARQ-ACK Feedback Parameter Determination in TDD Carrier Aggregation
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Solution Overview
Problem
Current wireless communication systems face limitations in communication flexibility and efficiency, particularly in handling Hybrid Automatic Repeat Request Acknowledgement/Negative Acknowledgement (HARQ-ACK) transmissions for multiple Physical Downlink Shared Channels (PDSCHs) in Time-Division Duplexing (TDD) scenarios with different uplink-downlink configurations.
Innovation Solution
The system determines a feedback parameter based on the configurations of primary and secondary cells to optimize HARQ-ACK feedback, allowing for efficient multiplexing and reporting of HARQ-ACK bits using different PUCCH formats, such as Format 3, 1a, and 1b, even in scenarios with conflicting subframes, by adjusting the number of subframes requiring feedback and applying appropriate channel selection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed communication structure is used for HARQ-ACK transmission, then implementation is simple, but communication flexibility and efficiency are limited
Solution Approach 1:
The patent implements dynamic determination of the feedback parameter Mc based on the actual number of downlink subframes requiring HARQ-ACK feedback in each uplink subframe. This allows the system to adapt flexibly to different TDD UL-DL configurations and carrier aggregation scenarios, resolving the contradiction by making the communication structure dynamic rather than fixed, thereby improving adaptability while maintaining manageable complexity through standardized determination rules
2Productivity
If the bundling window size is increased to handle multiple PDSCHs, then more feedback can be transmitted, but resource wastage increases in certain configurations
Solution Approach 1:
The patent dynamically adjusts the feedback parameter Mc (bundling window size) based on the actual number of downlink subframes that require HARQ-ACK feedback in each uplink subframe. This parameter adaptation allows the system to transmit adequate feedback for multiple PDSCHs when needed while avoiding resource wastage in configurations with fewer downlink subframes, thereby resolving the contradiction between feedback capacity and resource efficiency
3Adaptability or versatility
If different TDD UL-DL configurations are used for PCell and SCell, then carrier aggregation flexibility improves, but HARQ-ACK handling becomes more complex
Solution Approach 1:
The patent separately determines the feedback parameter Mc for each cell (PCell and SCell) based on their respective TDD UL-DL configurations and the actual number of downlink subframes requiring feedback. This segmented approach allows each cell to be optimized independently for its specific configuration, maintaining carrier aggregation flexibility while managing HARQ-ACK handling complexity through standardized per-cell determination rules rather than requiring complex joint optimization
Data Source
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AI summary
A User Equipment (UE) for sending information to a evolved Node B (eNB), the UE comprising: an operations unit configured to determine a Time-Division Duplexing (TDD) uplink-downlink (UL-DL) configuration of a primary cell (PCell), and to determine a TDD UL-DL configuration of a secondary cell (SCell), wherein the TDD UL-DL configuration of the SCell is different from the TDD UL-DL configuration of the PCell; and a transmitting unit configured to transmit Hybrid Automatic Repeat Request Acknowledgement/Negative Acknowledgement (HARQ-ACK) information, in a UL subframe for a cell, corresponding to DL subframes and special subframes within the elements in a set K associated with the UL subframe for the cell.