PDCCH Repetition DAI Handling for Clear HARQ Feedback
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently managing downlink assignment indexes (DAI) for control channel repetition, leading to increased UE complexity and potential performance issues due to soft combination of PDCCH repetitions.
Innovation Solution
A method and apparatus for wireless communication that involves monitoring and processing multiple control channel candidates with feedback codebooks to determine successful decoding of downlink control information (DCI) and associated data channels, utilizing downlink assignment indexes (DAI) to manage control channel repetition, and providing hybrid automatic repeat request (HARQ) feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If soft combination with PDCCH repetition over time is implemented, then control channel reception reliability is improved, but UE complexity and specification effort increase significantly
Solution Approach 1:
The patent extracts and eliminates the soft combination function from the UE implementation. Instead of requiring the UE to perform complex soft combining operations on multiple PDCCH repetitions, the system uses individual DCI acknowledgments for each repetition, simplifying the UE processing while maintaining reliability through redundant transmissions.
Solution Approach 2:
The patent segments the acknowledgment process into separate DCI-level acknowledgments for each PDCCH repetition rather than a single transport block-level acknowledgment. This segmentation allows the UE to independently acknowledge each received DCI, reducing the complexity of managing soft combined data while ensuring reliable delivery.
2Measurement precision
If multiple control channel candidates are monitored with separate feedback codebooks, then decoding accuracy is improved, but feedback overhead and processing complexity increase
Solution Approach 1:
The patent creates a universal feedback mechanism where a single feedback codebook structure handles multiple control channel candidates. Each DCI received on different PDCCH candidates generates an acknowledgment in the same feedback codebook, eliminating the need for separate codebooks while maintaining the ability to accurately track decoding status of each candidate.
Solution Approach 2:
The patent merges multiple potential feedback codebooks into a single unified feedback codebook that accommodates acknowledgments for all monitored control channel candidates. This consolidation reduces feedback overhead and simplifies UE processing while preserving the precision needed to identify which specific DCIs were successfully decoded.
3Reliability
If control channel repetition is implemented without DAI operation, then coverage enhancement is achieved, but feedback ambiguity and error rates increase
Solution Approach 1:
The patent implements a feedback mechanism using downlink assignment indexes (DAI) within each DCI transmitted on repeated PDCCH candidates. The DAI provides unique identification for each DCI instance, allowing the UE to generate precise acknowledgments that clearly indicate which specific DCI was successfully received, eliminating feedback ambiguity while maintaining coverage enhancement benefits.
Solution Approach 2:
The patent incorporates DAI information in advance within each DCI transmission before the acknowledgment phase. This preliminary inclusion of identification information allows the UE to unambiguously associate each received DCI with its corresponding acknowledgment, preventing information loss and feedback errors during the repetition process.
Data Source
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AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may monitor a first control channel candidate for first downlink control information (DCI) scheduling a data channel and a second control channel candidate for second DCI scheduling the data channel, wherein the first control channel candidate and the second control channel candidate are associated with a control channel repetition scheme. The UE may transmit a feedback codebook regarding the data channel based at least in part on monitoring the first control channel candidate and the second control channel candidate, wherein the feedback codebook includes one of: a single position corresponding to the data channel, or a first position corresponding to the first DCI on the first control channel candidate and a second position corresponding to the second DCI on the second control channel candidate. Numerous other aspects are provided.