HARQ-ACK Codebook Handling for Disabled Feedback in 5G NTN
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Solution Overview
Problem
Existing 5G NR systems integrating Non-Terrestrial Networks (NTN) face challenges in HARQ-ACK codebook handling, particularly for Type-2, Type-1, and Type-3 HARQ-ACK codebooks, due to unclear HARQ feedback configurations and bit construction for SPS PDSCH, counter DAI and total DAI counting, and feedback bits for HARQ processes with disabled feedback.
Innovation Solution
The solution involves determining HARQ feedback configurations for each HARQ process, generating HARQ-ACK codebooks based on these configurations, and handling feedback bits and NDI bits for processes with enabled or disabled feedback, including schemes for ordering and including bits in the codebooks to optimize size and content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If HARQ feedback is disabled for certain HARQ processes to reduce overhead, then codebook size is reduced, but reliability of HARQ acknowledgment is worsened
Solution Approach 1:
The patent segments HARQ processes into two categories: those with HARQ feedback enabled and those with HARQ feedback disabled. This segmentation allows the system to selectively include or exclude feedback bits in the HARQ-ACK codebook based on the feedback configuration of each individual HARQ process, thereby reducing codebook size for processes where feedback is disabled while maintaining reliability for processes where feedback is enabled.
Solution Approach 2:
The patent applies local quality by allowing different HARQ processes to have different feedback configurations (enabled or disabled) based on local requirements. Each HARQ process can be independently configured, enabling the system to optimize codebook size for specific processes without compromising the reliability of other processes that require feedback.
2Device complexity
If counter DAI field is reserved for HARQ processes with feedback disabled, then DCI structure is simplified, but information transmission completeness is worsened
Solution Approach 1:
The patent extracts the counter DAI field from active HARQ processes and reserves it for processes with feedback disabled. This extraction allows the DCI structure to be simplified by using a standardized field format while the actual DAI information is derived through calculation based on the total number of HARQ processes and the feedback configuration, preventing information loss.
Solution Approach 2:
The patent introduces the total DAI field as an intermediary that carries the total number of HARQ processes information. This intermediary enables the terminal to calculate the counter DAI for reserved fields without directly transmitting incomplete DAI information, thus maintaining information completeness while simplifying the DCI structure.
3Quantity of substance
If HARQ feedback configuration is not provided for SPS PDSCH in NTN, then configuration overhead is reduced, but feedback handling clarity is worsened
Solution Approach 1:
The patent applies universality by using the same HARQ feedback configuration mechanism for both scheduled PDSCH and SPS PDSCH in NTN. The network device can uniformly enable or disable HARQ feedback for HARQ processes associated with SPS PDSCH using the existing feedback configuration fields, eliminating the need for separate configuration procedures and improving operational clarity.
Solution Approach 2:
The patent implements preliminary action by pre-configuring HARQ feedback configurations for all HARQ processes, including those associated with SPS PDSCH, before actual PDSCH transmission. This preliminary configuration ensures that the terminal device has clear feedback handling instructions in advance, resolving the clarity issue while maintaining low overhead through reuse of existing configuration structures.
Data Source
AI summary
Embodiments of the present disclosure relate to methods, devices and computer readable storage media for hybrid automatic repeat request acknowledgement (HARQ-ACK) codebook handling. In example embodiments, a method is provided. The method comprises determining, at a terminal device, respective hybrid automatic repeat request (HARQ) feedback configurations of a plurality of HARQ processes, wherein each HARQ feedback configuration indicates whether HARQ feedback is enabled or disabled for a corresponding HARQ process; and generating a HARQ-ACK codebook for Physical Downlink Shared Channel (PDSCH) based on the HARQ feedback configurations of the plurality of HARQ processes; and transmitting the HARQ-ACK codebook to a network device.