ACK/NACK Feedback Transmission Using PUCCH Format 1a/1b
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Solution Overview
Problem
In LTE TDD systems, Rel-10 UEs without carrier aggregation face a lack of ACK/NACK transmission mechanisms when configured to use PUCCH format 3, especially when receiving only SPS PDSCH and a PDCCH with a DL DAI value of 1 in the feedback window, leading to incomplete feedback and potential misinterpretation of control signaling.
Innovation Solution
The method involves transmitting ACK/NACK feedback information using PUCCH format 1a/1b resources by the UE, employing ACK/NACK bundling or channel selection, and utilizing specific LTE-A mapping tables to determine the correct PUCCH resources for SPS PDSCH and PDCCH, ensuring accurate feedback even when PUCCH format 3 resources are not available.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If PUCCH format 3 is configured for ACK/NACK transmission, then the feedback capacity is improved, but the device complexity increases and resource availability decreases for certain UE scenarios
Solution Approach 1:
The patent changes the PUCCH format parameter from format 3 to format 1a/1b based on the feedback scenario, allowing Rel-10 UEs to adapt to different transmission requirements without being constrained by the initially configured format 3, thus reducing device complexity while maintaining feedback capacity
Solution Approach 2:
The patent introduces dynamic selection between PUCCH format 1a/1b and format 3 based on whether the UE can obtain format 3 resources, making the system flexible and adaptive to different resource availability scenarios rather than being static
2Reliability
If PUCCH format 3 resources are not obtainable, then resource availability decreases, but the feedback transmission must still be reliable
Solution Approach 1:
The patent prepares alternative PUCCH format 1a/1b resources in advance for scenarios where format 3 resources are not available, ensuring that feedback transmission can immediately switch to a reliable alternative without interruption or loss of feedback reliability
Solution Approach 2:
The patent introduces an intermediate mechanism (PUCCH format 1a/1b) that mediates between the ideal scenario (PUCCH format 3) and the constrained scenario (no format 3 resources), providing a fallback path that maintains feedback reliability when the primary resource is unavailable
3Quantity of substance
If ACK/NACK bundling is used, then the transmission overhead is reduced, but the measurement precision of feedback information decreases
Solution Approach 1:
The patent applies ACK/NACK bundling partially - only when PUCCH format 3 resources are not obtainable and for specific UE scenarios (Rel-10 UEs without carrier aggregation), while maintaining full feedback precision through format 3 when resources are available, thus balancing overhead reduction with precision preservation
Data Source
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AI summary
The present disclosure provides a method and an apparatus for ACK/NACK transmission. When a terminal device only received a semi-persistent scheduling (SPS) physical downlink shared channel (PDSCH) and a physical downlink control channel (PDCCH) in which a downlink assignment index (DAI) value is equal to 1 in a feedback window, the terminal device transmits ACK/NACK feedback information corresponding to the SPS PDSCH and ACK/NACK feedback information corresponding to the PDCCH on PUCCH format 1a/1b resource using PUCCH format 1b with channel selection or ACK/NACK bundling. Therefore, when a base station configures PUCCH format 3 resource for transmitting feedback but the terminal device cannot obtain the PUCCH format 3 resource, ACK/NACK can still be transmitted.