Type-1 HARQ-ACK Codebook for SPS Deferral
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Solution Overview
Problem
The existing Type-1 HARQ-ACK codebook construction in 3GPP NR systems does not fully support Semi-Persistent Scheduling (SPS) HARQ-ACK deferral, leading to dropped HARQ feedback in TDD operations due to mismatches between SPS periodicity and TDD patterns, particularly in asymmetric DL/UL configurations.
Innovation Solution
Modifying the set of K1 values used in Type-1 codebook construction to include deferred SPS HARQ-ACK bits, allowing for their inclusion in the codebook and ensuring they are transmitted in the next available UL slot, thereby preventing HARQ feedback dropout.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the existing Type-1 HARQ-ACK codebook construction is used, then the codebook structure remains simple and standardized, but SPS HARQ-ACK deferral is not fully supported leading to feedback dropout in TDD operations
Solution Approach 1:
The patent introduces dynamic modification to the static Type-1 codebook construction process. The network node dynamically determines whether to apply the modified construction method based on whether SPS HARQ-ACK deferral is configured, and the wireless device dynamically adjusts its codebook generation accordingly. This dynamic adaptation enables the system to handle both standard and deferred SPS HARQ-ACK cases without permanent complexity increase.
Solution Approach 2:
The patent modifies the K1 value selection parameter in the codebook construction process. Instead of using only the originally configured K1 value, the system now considers modified K1 values that account for deferral scenarios. This parameter change ensures that the codebook includes appropriate placeholder bits for deferred SPS HARQ-ACK feedback, preventing feedback dropout while maintaining compatibility with existing standards.
2Adaptability or versatility
If SPS HARQ-ACK deferral is implemented, then feedback transmission adapts to TDD patterns, but mismatches between SPS periodicity and TDD patterns cause dropped HARQ feedback
Solution Approach 1:
The patent applies preliminary action by pre-allocating placeholder bits in the HARQ-ACK codebook for potential deferred SPS HARQ-ACK feedback before the actual deferral occurs. The network node and wireless device both prepare the codebook structure in advance with appropriate placeholders, ensuring that when deferral happens, the feedback can be properly accommodated without dropout. This proactive preparation prevents the reliability issue caused by periodicity-TDD pattern mismatches.
3Reliability
If the set of K1 values is modified to include deferred SPS HARQ-ACK bits, then HARQ feedback dropout is prevented, but the codebook construction process becomes more complex
Solution Approach 1:
The patent implements a feedback mechanism where the network node indicates to the wireless device whether the modified Type-1 codebook construction should be used. This feedback allows the wireless device to adjust its codebook generation process accordingly, maintaining ease of construction through clear signaling while ensuring reliable feedback completeness when deferral is active. The feedback loop enables the system to switch between simple and modified construction modes as needed.
Data Source
AI summary
A method, system and apparatus are disclosed. According to some embodiments, a wireless device is provided. The wireless device includes processing circuitry configured to generate a first HARQ-ACK codebook for a first uplink time slot, where the first HARQ-5 ACK codebook includes a first plurality of HARQ-ACK bits, to determine a second plurality of HARQ-ACK bits, where each of the second plurality of HARQ-ACK bits is associated with a respective timing parameter, and each of the second plurality of HARQ-ACK bits is mapped to a respective downlink time slot of a plurality of downlink time slots based on the respective timing parameter, to modify the first HARQ-ACK codebook based on at least one 0 deferred HARQ-ACK bit of the second plurality of HARQ-ACK bits, and to cause transmission of the modified first HARQ-ACK codebook during the first uplink time slot.