Dynamic HARQ-ACK Codebook for Multi-PDSCH Single-DCI Scheduling
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Solution Overview
Problem
The enhancement of multiple PDSCH scheduling by a single DCI in NR Release 17 for higher Subcarrier Spacing values poses challenges in HARQ-ACK codebook construction, particularly in counting Downlink Assignment Indicators (C-DAI and T-DAI) and indexing of PDSCHs, leading to ambiguity in detecting missed PDSCH transmissions.
Innovation Solution
The proposed solution involves determining the number of sub-HARQ-ACK codebooks and their construction, employing PDSCH indexing for dynamic HARQ-ACK codebook construction, and time-domain bundling of HARQ-ACK bits for multiple PDSCH transmissions scheduled by a single DCI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple PDSCH are scheduled by a single DCI, then scheduling efficiency is improved, but HARQ-ACK codebook construction complexity increases
Solution Approach 1:
The patent divides the HARQ-ACK codebook into multiple sub-codebooks, where each sub-codebook corresponds to a specific serving cell or PDSCH group. This segmentation allows the UE to construct codebooks for each subset separately and then concatenate them, reducing the overall construction complexity while supporting multiple PDSCH scheduled by a single DCI.
Solution Approach 2:
The patent introduces a new dimension for codebook construction by using PDSCH indexing and time-domain bundling as additional organizational layers. Instead of constructing a single flat codebook, the solution creates a hierarchical structure with sub-codebooks organized by serving cell index and time domain, making the construction process more manageable.
2Measurement precision
If dynamic HARQ-ACK is applied with counter DAI on DCI basis, then feedback accuracy is improved, but determining missed PDSCH becomes difficult when multiple PDSCH are scheduled by single DCI
Solution Approach 1:
The patent enhances feedback mechanisms by incorporating PDSCH indexing information and time-domain bundling indicators into the HARQ-ACK codebook. This allows the gNB to accurately determine which specific PDSCH were received or missed by the UE, even when multiple PDSCH are scheduled by a single DCI, by providing detailed feedback at the PDSCH level rather than just DCI level.
Solution Approach 2:
The patent introduces PDSCH indexing as an intermediary element between DCI and HARQ-ACK feedback. The indexing mechanism acts as a mediator that links the single DCI to multiple scheduled PDSCH, enabling the system to track and provide feedback for each individual PDSCH transmission separately, thus preventing information loss about missed PDSCH.
3Ease of operation
If HARQ-ACK sequencing is based on serving cell index and time occurrence, then codebook organization is improved, but processing overhead increases
Solution Approach 1:
The patent merges multiple organization criteria (serving cell index and time occurrence) into a unified codebook structure. By combining these dimensions, the patent achieves well-organized codebooks that group PDSCH by serving cell first, then by time occurrence within each cell, reducing processing overhead compared to handling each dimension separately.
Solution Approach 2:
The patent changes the organizational parameters of the codebook from a flat structure to a hierarchical one based on serving cell index and time domain. This parameter change optimizes the codebook structure for efficient processing by the gNB, allowing it to systematically determine which PDSCH were missed by comparing the received codebook against the expected structure.
Data Source
AI summary
Apparatuses, methods, and systems are disclosed for HARQ-ACK feedback for multiple downlink transmissions. One method includes receiving receive DCI for scheduling a plurality of downlink transmissions on a plurality of serving cells, wherein downlink transmissions scheduled on a respective serving cell include a set of downlink transmissions scheduled by a single DCI. The method includes determining HARQ-ACK feedback for the plurality of downlink transmissions and determining a sequence of HARQ-ACK bits corresponding to the HARQ-ACK feedback, where the sequence of HARQ-ACK bits is ordered based at least in part on a serving cell index and an occurrence in time of a respective DCI corresponding to the plurality of downlink transmissions. The method includes transmitting the sequence of HARQ-ACK bits.