TDD Carrier Aggregation HARQ-ACK Resource Management
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Solution Overview
Problem
Current wireless communication systems face inefficiencies in transmitting control information, particularly in time division duplex (TDD) systems, where managing uplink control information and resources is challenging, especially with carrier aggregation.
Innovation Solution
A method and apparatus for transmitting uplink control information in a wireless communication system supporting carrier aggregation and operating in TDD, involving the generation of hybrid automatic repeat request-acknowledgement (HARQ-ACK) sets for multiple cells using specific L1 and L2 values, and transmitting these through a physical uplink shared channel (PUSCH) with spatial bundling, where the number of HARQ-ACK responses is determined by the uplink-downlink assignment index (UL DAI) to efficiently manage resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If carrier aggregation is implemented in TDD systems, then system capacity and spectral efficiency are improved, but the complexity of managing uplink control information and HARQ-ACK sets increases
Solution Approach 1:
The patent segments the HARQ-ACK information into separate sets (first HARQ-ACK set and second HARQ-ACK set) corresponding to different cells or carrier components. This segmentation allows independent management and transmission of control information for each carrier, reducing the overall complexity while maintaining the benefits of carrier aggregation.
Solution Approach 2:
The patent applies different processing methods and parameters (L1 values, L2 values) to different HARQ-ACK sets based on their specific characteristics and associated cells. This local quality approach optimizes control information management for each carrier while maintaining system-wide efficiency.
2Reliability
If the number of HARQ-ACK responses is increased to cover more downlink subframes, then feedback completeness is improved, but the resource consumption for transmission increases
Solution Approach 1:
The patent dynamically determines the number of HARQ-ACK responses based on the uplink-downlink assignment index (UL DAI) value. When UL DAI is 1 or 2, the patent uses L1=min(M1, W) and L2=min(M2, W) to limit the number of responses. When UL DAI is 3 or 4, it uses L1=L2=W. This dynamic adjustment ensures feedback completeness matches actual transmission needs, avoiding resource waste.
Solution Approach 2:
The patent changes the parameter W (uplink downlink assignment index) to control the number of HARQ-ACK responses transmitted. By adjusting W based on actual downlink subframe configurations and transmission needs, the system optimizes the balance between feedback completeness and resource consumption.
3Productivity
If spatial bundling is applied to reduce the number of HARQ-ACK sets, then transmission efficiency is improved, but the precision of individual cell feedback is reduced
Solution Approach 1:
The patent segments HARQ-ACK information into cell-specific sets (first HARQ-ACK set for first cell, second HARQ-ACK set for second cell) while allowing spatial bundling at the carrier level. This segmentation maintains individual cell feedback precision while enabling efficient transmission through spatial bundling of multiple cells.
Solution Approach 2:
The patent maintains different processing characteristics for different cells through separate HARQ-ACK sets, allowing each cell to have its feedback precisely managed while benefiting from spatial bundling optimizations at the carrier level.
Data Source
AI summary
The present invention relates to a wireless communication system. More particularly, the present invention relates to a method and an apparatus for transmitting uplink control information in the wireless communication system, which supports carrier aggregation and operates by a TDD, and comprises the steps of: generating a first HARQ-ACK set with respect to a first cell by using an L1 value; generating a second HARQ-ACK set with respect to a second cell by using an L2 value; and transmitting bit values, which correspond to the first and second HARQ-ACK sets are transmitted through a PUSCH from a subframe n, wherein L1=min (M1, W) and L2=min (M2, W) when the value (W) of a UL DAI corresponding to the PUSCH is 1 or 2, and L1=L2=W when the value (W) of the UL DAI corresponding to the PUSCH is 3 or 4, wherein min (A, B) represents a smaller number from A and B, M1 corresponds to the number of downlink subframes that correspond to an uplink subframe n with respect to the first cell, M2 corresponds to a the number of downlink subframes that correspond to the uplink subframe n with respect to the second cell, wherein the first cell and the second cell have different UL-DL configurations.