Type 2 HARQ Codebook Construction with PDCCH Repetitions
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Solution Overview
Problem
In the context of New Radio (NR) communications, constructing a Type 2 Hybrid Automatic Repeat Request (HARQ) Acknowledgement (ACK) codebook is challenging in the presence of Physical Downlink Control Channel (PDCCH) repetitions, leading to incorrect mapping and counting of HARQ ACK bits.
Innovation Solution
A method is proposed where the first PDCCH occasion is defined among multiple PDCCH occasions, and the counter field in the corresponding Downlink Control Information (DCIs) is incremented only at this occasion, enabling Type 2 HARQ ACK codebook construction with minimal specification changes, even in cases of PDCCH repetitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PDCCH repetitions are used to improve control channel reliability, then the reliability of control information transmission is improved, but the complexity of HARQ codebook construction increases and leads to incorrect ACK bit counting
Solution Approach 1:
The patent applies preliminary action by defining a reference PDCCH occasion in advance before HARQ-ACK bits are generated. The network device pre-configures which PDCCH occasion (first, second, or third) should be used as the reference for codebook construction. This allows the terminal to correctly identify the reference occasion and generate HARQ-ACK bits in the proper sequence, resolving the complexity issue while maintaining the reliability benefits of PDCCH repetitions.
2Reliability
If PDCCH repetitions are configured with multiple occasions, then the coverage and reliability are improved, but the mapping of HARQ ACK bits becomes incorrect
Solution Approach 1:
The patent introduces a reference PDCCH occasion as an intermediary element that mediates between the multiple PDCCH repetition occasions and the HARQ-ACK bit generation process. This reference occasion serves as a anchor point that the terminal uses to correctly map HARQ-ACK bits to their corresponding PDCCH occasions, ensuring accurate mapping even when multiple repetitions are present.
3Loss of information
If the counter field is incremented at every PDCCH occasion, then all PDCCH transmissions are accounted for, but the codebook construction becomes incorrect in the presence of repetitions
Solution Approach 1:
The patent extracts the counter increment operation from being applied at every PDCCH occasion and restricts it to only the reference PDCCH occasion. By taking out the counter increment action from the general PDCCH processing and applying it selectively only at the predefined reference occasion, the patent ensures that each PDCCH transmission is accounted for without causing duplicate counting or mapping errors in the codebook construction.
Data Source
AI summary
Systems and methods for codebook determination are provided herein. In some embodiments, a method performed by a wireless device for constructing a codebook includes: defining a first Physical Downlink Control Channel (PDCCH) occasion among multiple PDCCH occasions associated with a PDCCH; identifying the first PDCCH occasion for each detected Downlink Control Information (DCI); and constructing a codebook based on the first PDCCH occasion of all detected PDCCHs with a counter field in the corresponding DCIs. In this way, Type 2 Hybrid Automatic Repeat Request (HARQ) Acknowledgement (ACK) codebook construction is enabled in the presence of PDCCH repetitions with minimum specification changes.