Multi-Cell Scheduling With Unified HARQ-ACK Codebooks
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Solution Overview
Problem
Existing 5G NR systems face inefficiencies in multi-cell scheduling due to high signaling overhead and lack of support for joint scheduling of multiple PDSCHs or PUSCHs across multiple cells using a single DCI format, leading to repeated scheduling parameters and increased CRC field overhead, especially in scenarios with a large number of co-scheduled cells.
Innovation Solution
The implementation of multi-cell scheduling using a single DCI format to jointly schedule multiple cells, with enhanced Type-2 HARQ-ACK codebooks that include counter/total DAI definitions and HARQ-ACK information bit ordering, reducing signaling overhead by appending HARQ-ACK information bits into a single HARQ-ACK codebook for PUCCH or PUSCH transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple DCI formats are used to schedule PDSCH on each cell individually, then scheduling flexibility is maintained, but signaling overhead increases due to repeated parameters and multiple CRC fields
Solution Approach 1:
The patent merges multiple DCI formats into a single DCI format that can schedule multiple PDSCH across multiple cells simultaneously. This consolidation eliminates the need for separate DCI messages for each cell, thereby reducing signaling overhead while maintaining scheduling flexibility through unified resource allocation mechanisms.
Solution Approach 2:
The DCI format is designed with multi-functionality to handle scheduling for multiple cells and multiple PDSCH transmissions within a single message structure. This universal format includes flexible field configurations that can adapt to different cell combinations and scheduling scenarios, replacing the need for cell-specific DCI variants.
2Reliability
If HARQ-ACK feedback is transmitted separately for each DCI format, then acknowledgment accuracy is maintained, but control signaling overhead increases
Solution Approach 1:
The patent combines HARQ-ACK feedback for multiple PDSCH receptions into a single unified HARQ-ACK codebook. Instead of transmitting separate ACK/NACK messages for each DCI format, the system generates one consolidated codebook that encompasses acknowledgments for all scheduled transmissions, thereby reducing control signaling overhead while preserving complete acknowledgment coverage.
Solution Approach 2:
The HARQ-ACK codebook structure uses bit mapping and copying mechanisms to efficiently represent acknowledgments for multiple PDSCH. Each PDSCH reception corresponds to specific bits in the codebook, allowing the system to convey comprehensive acknowledgment information in a compact format without losing accuracy.
3Quantity of substance
If a single DCI format schedules multiple PDSCH on multiple cells, then signaling overhead is reduced, but complexity of HARQ-ACK codebook generation increases
Solution Approach 1:
The patent segments the HARQ-ACK codebook generation process into manageable components: identifying PDSCH receptions, determining corresponding DCI formats, mapping to codebook bits, and appending acknowledgments. This structured segmentation simplifies the overall complexity by breaking down the monolithic codebook generation into systematic steps that can be implemented efficiently.
Solution Approach 2:
The system performs preliminary actions by pre-defining the codebook structure, bit mapping rules, and acknowledgment ordering before actual HARQ-ACK transmission. This preliminary setup includes establishing the relationship between PDSCH receptions and codebook bits, which simplifies the real-time generation process and reduces computational complexity during operation.
Data Source
AI summary
A method for acknowledgement information enhancement includes receiving first information for first cells; second information for second cells; first and second DCI formats; and N PDSCHs on N cells, from the second cells, which are scheduled by a DCI format from the second DCI formats. The method further includes determining first HARQ-ACK information bits associated with the first DCI formats and second HARQ-ACK information bits associated with the second DCI formats. The second HARQ-ACK information bits include, for the DCI format, M=Σi∈N Mi HARQ-ACK information bits corresponding to receptions of the N PDSCHs on N cells, in ascending order of cell indexes for the N cells and (Mmax−M) HARQ-ACK information bits with NACK values that are appended to the M HARQ-ACK information bits. The method further transmitting a channel that includes a HARQ-ACK codebook generated by appending the second HARQ-ACK information bits to the first HARQ-ACK information bits.