HARQ-ACK Feedback Accuracy in LTE TDD Dynamic Configuration
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Solution Overview
Problem
In LTE TDD systems, the dynamic configuration of uplink-downlink configurations can lead to incorrect HARQ-ACK feedback due to the DAI in the UL Grant not indicating the total number of PDSCHs and downlink SPS release signaling, resulting in incorrect HARQ-ACK information being fed back by the UE.
Innovation Solution
A control information feedback method that determines HARQ-ACK information based on a downlink reference configuration, allowing the UE to correctly determine the downlink association set and timing, ensuring accurate feedback even when the UL Grant is transmitted before the last subframe in the HARQ-ACK bundling subframe set.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the UL Grant is transmitted before the last subframe in the HARQ-ACK bundling subframe set due to dynamic uplink-downlink configuration, then the scheduling flexibility is improved, but the DAI in the UL Grant does not indicate the total number of PDSCHs and downlink SPS release signaling, resulting in incorrect HARQ-ACK feedback
Solution Approach 1:
The patent introduces a preliminary counting mechanism where the UE counts the total number of PDSCHs and downlink SPS release signaling received in the HARQ-ACK bundling subframe set before generating HARQ-ACK feedback. This preliminary action ensures that the UE has accurate information about the total number of downlink transmissions, allowing it to correctly determine HARQ-ACK information even when the UL Grant is transmitted early, thus resolving the reliability issue while maintaining scheduling flexibility
Solution Approach 2:
The patent uses the downlink association set K as an intermediary mechanism. By determining the downlink association set based on the downlink reference configuration and using it to identify the HARQ-ACK bundling subframe set, the system creates a reliable reference framework that mediates between the dynamic UL Grant transmission timing and the static HARQ-ACK feedback requirements, ensuring accurate feedback generation
2Ease of operation
If the DAI in the UL Grant is used to determine HARQ-ACK information, then the feedback process is simplified, but the DAI does not indicate the total number of PDSCHs and downlink SPS release signaling when UL Grant is transmitted early, leading to incorrect feedback
Solution Approach 1:
The patent applies preliminary counting of PDSCHs and downlink SPS release signaling before HARQ-ACK feedback generation. This preliminary action establishes the correct total number of downlink transmissions, which the UE then uses to accurately determine HARQ-ACK information, maintaining both simplicity and precision in the feedback process
Solution Approach 2:
The patent implements a feedback mechanism where the UE determines HARQ-ACK information based on the counted total number of PDSCHs and downlink SPS release signaling. This feedback process ensures that the HARQ-ACK information accurately reflects the actual downlink transmission status, resolving the precision issue while keeping the process straightforward
Data Source
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AI summary
The present invention provides a control information feedback method, a user equipment, and a base station. The control information feedback method includes: receiving, by a UE, a UL Grant in a subframe n-k', where the UL Grant is used to indicate PUSCH transmission in a subframe n, and k' is an uplink association index; determining, HARQ-ACK information according to a downlink reference configuration, where the HARQ-ACK information is carried on the PUSCH; and transmitting the PUSCH in the subframe n. In the present invention, the HARQ-ACK information is determined according to the downlink reference configuration, so that it is unnecessary to determine the HARQ-ACK information according to a value indicated by a DAI in the UL Grant, thereby avoiding a technical problem of feeding back incorrect HARQ-ACK information.