HARQ Codebook Segmentation for Multiple PUCCH Payload Balancing
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Solution Overview
Problem
Existing methods for constructing Hybrid Automatic Repeat Request (HARQ) codebooks in New Radio (NR) are inefficient when multiple Physical Uplink Control Channels (PUCCH) are used within a slot, leading to unbalanced payload size distribution and resource utilization inefficiencies.
Innovation Solution
A method for constructing a semi-static HARQ codebook for multiple PUCCH resources within a slot by determining sub-Time Domain Resource Allocation (TDRA) tables, pruning entries with overlapping allocations, and reserving bits for each non-overlapping entry, based on PDSCH-to-HARQ_feedback timing indicators (K1) and grouping PDSCHs into multiple PUCCH transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single HARQ codebook is constructed for multiple PUCCH resources, then the feedback mechanism is simplified, but the payload size distribution becomes unbalanced and resource utilization is inefficient
Solution Approach 1:
The patent divides the single HARQ codebook into multiple separate codebooks, with each codebook corresponding to a specific PUCCH resource. This segmentation allows each codebook to be optimized for its specific payload requirements, achieving balanced payload size distribution and improved resource utilization efficiency across multiple PUCCH resources within a slot.
2Ease of manufacture
If semi-static codebook is used, then the codebook size is preconfigured and fixed, but bits are reserved regardless of actual PDSCH scheduling leading to overhead
Solution Approach 1:
The patent employs dynamic codebook construction for each PUCCH resource, where the codebook size and structure are determined based on the actual scheduled PDSCH transmissions rather than being fixed in advance. This dynamic approach allows the codebook to adapt to actual scheduling conditions, eliminating unnecessary reserved bits and reducing overhead while maintaining configuration simplicity through higher layer signaling.
3Speed
If multiple PUCCH resources are used within a slot, then low latency feedback is enabled, but existing HARQ codebook methods become inefficient
Solution Approach 1:
The patent segments the HARQ codebook construction process by creating separate codebooks for each PUCCH resource, allowing independent optimization of each codebook for its specific timing and payload requirements. This enables efficient codebook construction that accommodates multiple PUCCH resources within a slot while maintaining low latency feedback performance.
Solution Approach 2:
The patent performs preliminary actions by determining the set of possible PDSCH-to-HARQ feedback timing indicators (K1 values) for each PUCCH resource in advance, and pre-configuring the codebook structures through higher layer signaling. This preparation enables efficient codebook construction when multiple PUCCH resources are active, maintaining both low latency feedback and high construction efficiency.
Data Source
AI summary
Systems and methods of HARQ codebook determination for multiple PUCCH are disclosed. In some embodiments, a method performed by a base station for constructing a semi-static HARQ codebook for each of multiple PUCCH resources in an uplink slot, each of the multiple PUCCH resources carrying HARQ feedback for PDSCH transmissions within a certain downlink time interval. The base station, based on a TDRA table, determines a sub-TDRA table for each downlink time interval comprising entries of the TDRA table with a TDRA ending in the downlink time interval. This includes pruning each sub-TDRA table to remove entries with overlapping TDRAs. The semi-static HARQ codebook is constructed for each pruned sub-TDRA table based on the remaining entries in the pruned sub-TDRA tables. The semi-static HARQ codebook is transmitted to the wireless device. In this way, it is possible to construct a semi-static HARQ codebook for multiple PUCCH transmission within a slot.