PUCCH Resource Determination for HARQ-ACK in CA TDD Systems
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Solution Overview
Problem
In LTE-A TDD systems, determining PUCCH resources is challenging when carrier aggregation is performed with serving cells having different uplink-downlink configurations, particularly when using PUCCH format 1b with channel selection for HARQ-ACK transmission.
Innovation Solution
A method to determine PUCCH resources by establishing a timing relationship between the PDSCH and HARQ-ACK information for secondary serving cells, allowing for accurate transmission mode and resource allocation even when serving cells have distinct uplink-downlink configurations, using candidate schemes to ensure proper HARQ-ACK feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If carrier aggregation is performed with serving cells having different uplink-downlink configurations, then the system can support more diverse service scenarios and increase bandwidth utilization, but determining PUCCH resources for HARQ-ACK transmission becomes complex and ambiguous
Solution Approach 1:
The patent applies local quality by configuring different uplink-downlink configurations for different serving cells based on their specific service requirements. Each serving cell can have its own configuration (e.g., configuration 0 for one cell, configuration 1 for another), allowing localized optimization while maintaining overall system functionality through the channel selection mechanism.
Solution Approach 2:
The patent implements universality through the channel selection mechanism that can handle multiple HARQ-ACK bits (up to 4 bits) using a unified PUCCH resource. The same PUCCH resource and channel selection table are used regardless of which combination of downlink subframes are being acknowledged, providing a universal solution for resource determination across different configuration scenarios.
2Productivity
If PUCCH format 1b with channel selection is used for HARQ-ACK transmission, then the transmission efficiency is improved, but the resource determination becomes ambiguous when serving cells have different configurations
Solution Approach 1:
The patent applies preliminary action by pre-configuring the channel selection table and PUCCH resources through higher layer signaling before transmission occurs. The network configures the specific PUCCH resource and provides the channel selection table in advance, so that both the terminal and network have clear, unambiguous resource determination rules ready before the actual HARQ-ACK transmission takes place.
Solution Approach 2:
The patent uses higher layer signaling as an intermediary to transmit the channel selection table and PUCCH resource configuration from the network to the terminal. This intermediary mechanism ensures that the resource determination information is accurately and unambiguously communicated, resolving the ambiguity problem through a reliable configuration channel.
3Quantity of substance
If multiple downlink subframes are bundled into one feedback window, then the feedback overhead is reduced, but the timing relationship between PDSCH and HARQ-ACK becomes difficult to manage with different configurations
Solution Approach 1:
The patent applies dynamics by allowing the feedback window composition to vary dynamically based on the specific uplink-downlink configurations of the aggregated serving cells. The feedback window is determined by the intersection of downlink subframes across all serving cells that can be acknowledged in a given uplink subframe, adapting to different configuration scenarios while maintaining efficient bundling.
Data Source
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AI summary
A method and apparatus for transmitting HARQ-ACK information are provided. The method includes: in a CA TDD system, when uplink-downlink configurations of aggregated serving cells are different, and a mode of PUCCH format 1b with channel selection is configured to be used to feed back the HARQ-ACK, determining, according to a timing relationship between the PDSCH and the HARQ-ACK information complied by a secondary serving cell, a set of downlink subframes of aggregated serving cells in a feedback window corresponding to an uplink subframe; and determining, according to the relationship between the sets of downlink subframes of the aggregated serving cells in a feedback window corresponding to uplink subframe, the transmission mode of the HARQ-ACK information of the serving cells and the used PUCCH resources when transmitting the HARQ-ACK information; and on the determined PUCCH resources, transmitting the HARQ-ACK information by using the determined transmission mode of the HARQ-ACK information.