HARQ-ACK Codebook Determination with Dynamic DAI Bitwidth
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Solution Overview
Problem
Wireless communication systems face challenges in scheduling errors due to mismatches in downlink assignment indicator (DAI) bitwidths across different DCI formats, which affect the determination of HARQ-ACK codebooks in wireless multiple-access communications.
Innovation Solution
The proposed solutions include configuring scheduling constraints through RRC signals, concatenating separate codebooks, using a single codebook in a joint feedback message, and converting DAI values between modulo operators to generate a unified codebook, allowing user equipment (UE) to manage and transmit feedback messages effectively despite varying DAI bitwidths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If different DCI formats with different DAI bitwidths are used for scheduling downlink transmissions, then scheduling flexibility and adaptability are improved, but scheduling errors occur due to DAI bitwidth mismatch in HARQ-ACK codebook determination
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the DAI bitwidth in DCI formats based on the HARQ-ACK codebook size. When the codebook size exceeds a threshold, the DAI bitwidth is increased from 2 bits to 3 bits, and the modulo operator is changed accordingly. This parameter adaptation allows the system to maintain scheduling flexibility with different DCI formats while preventing scheduling errors through consistent DAI bitwidth matching with the codebook size.
Solution Approach 2:
The patent implements dynamics by making the DAI bitwidth configurable and adaptable rather than fixed. The base station can dynamically select between 2-bit and 3-bit DAI formats depending on the current HARQ-ACK codebook size, and the UE adapts its codebook determination accordingly. This dynamic adjustment ensures that the scheduling mechanism remains flexible while maintaining accuracy across different operating conditions.
2Productivity
If a unified HARQ-ACK codebook is used for feedback transmission, then feedback efficiency is improved, but codebook size and complexity increase when accommodating multiple DCI formats with different DAI bitwidths
Solution Approach 1:
The patent applies parameter changes by adjusting the DAI bitwidth parameter in the DCI format to match the HARQ-ACK codebook size. When the codebook size is large (exceeding threshold), the DAI bitwidth is increased to 3 bits, which provides sufficient resolution for codebook determination without requiring separate codebooks for different DCI formats. This parameter adaptation maintains a unified codebook structure while accommodating multiple DCI formats, thus preserving feedback efficiency without excessive complexity increase.
3Measurement precision
If DAI bitwidth is increased to 3 bits to accommodate larger codebooks, then codebook determination accuracy is improved, but control signaling overhead increases
Solution Approach 1:
The patent implements dynamics by making the DAI bitwidth adaptable rather than fixed at 3 bits. The system dynamically selects between 2-bit and 3-bit DAI formats based on the current HARQ-ACK codebook size. When the codebook is small, 2-bit DAI is used to minimize overhead; when the codebook is large, 3-bit DAI is used to ensure accuracy. This dynamic approach balances precision requirements with signaling overhead efficiency.
Data Source
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AI summary
Methods, systems, and devices for wireless communications are described. A user equipment (UE) may receive a configuration signal identifying a scheduling constraint for the UE, the scheduling constraint for downlink feedback messages associated with a dynamic codebook configuration and scheduled using a first downlink control information (DCI) format. The UE may receive a first DCI having the first DCI format. The UE may determine, based at least in part on the first DCI format, that the scheduling constraint is satisfied. The UE may transmit a feedback message for the first downlink control information based at least in part on the scheduling constraint being satisfied.