Dynamic HARQ-ACK Codebook Construction for Multiple SPS Configurations
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently managing multiple active semi-persistent scheduling configurations, leading to ambiguity in ACK/NACK feedback and resource wastage due to the need to test multiple decoding hypotheses, especially when multiple SPS occasions are multiplexed in the same PUCCH resource.
Innovation Solution
The method involves incrementing the downlink association index (DAI) in downlink control information (DCI) to represent the number of SPS occasions multiplexed in a PUCCH communication, allowing for the construction of a Type 2 HARQ-ACK codebook that clearly differentiates between initial and subsequent SPS occasions, thereby reducing ambiguity and resource wastage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple SPS occasions are multiplexed in the same PUCCH resource, then resource utilization is improved, but ACK/NACK feedback ambiguity increases
Solution Approach 1:
The patent segments the DAI field into multiple parts: a counter DAI that counts the number of SPS occasions and a total DAI that indicates the total number of SPS occasions. This segmentation allows the UE to distinguish between different SPS occasions and construct the HARQ-ACK codebook accurately, eliminating feedback ambiguity while maintaining efficient resource utilization through multiplexing.
2Measurement precision
If multiple decoding hypotheses are tested to resolve ACK/NACK ambiguity, then feedback accuracy is improved, but base station resource consumption increases
Solution Approach 1:
The patent implements preliminary action by having the UE construct the HARQ-ACK codebook in advance using the counter DAI and total DAI values before transmission. The UE determines the exact number of SPS occasions and prepares the accurate feedback information, eliminating the need for the base station to test multiple decoding hypotheses and thereby reducing base station resource consumption while maintaining feedback accuracy.
3Measurement precision
If a Type 2 HARQ-ACK codebook is constructed using incremented DAI, then feedback precision is improved, but system complexity increases
Solution Approach 1:
The patent changes the parameter representation by using an incremented DAI field that directly encodes the number of SPS occasions. Instead of using complex signaling mechanisms or multiple fields, the DAI is simply incremented for each SPS occasion, providing a straightforward method for the UE to determine the codebook size and construct the Type 2 HARQ-ACK codebook with high precision while keeping the implementation relatively simple.
Data Source
AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive activation or reactivation downlink control information (DCI) for a semi-persistent scheduling (SPS) configuration, wherein the activation or reactivation DCI includes a downlink association index (DAI) that is incremented by: a value of one to represent an initial SPS communication associated with the SPS configuration, or a value equal to a number of SPS occasions that are multiplexed in a same physical uplink control channel (PUCCH) communication. The UE may transmit acknowledgement or negative acknowledgement (ACK/NACK) feedback in the PUCCH communication based at least in part on the DAI. Numerous other aspects are provided.