HARQ-ACK Feedback Timing in Wireless Communications
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Solution Overview
Problem
In communications systems, especially in LTE, the fixed timing sequence for HARQ-ACK feedback in FDD and TDD systems leads to issues with packet loss during flexible resource scheduling, where terminal devices cannot correctly feed back HARQ-ACK information due to incomplete reception of downlink data.
Innovation Solution
The method involves a base station sending downlink data with DCI indicating a target transmission time interval (TTI) for HARQ-ACK feedback, allowing the terminal device to determine the TTI based on feedback delay or index, enabling correct feedback even with packet loss by generating and sending HARQ-ACK feedback information in the specified TTI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fixed timing sequence for HARQ-ACK feedback is used in FDD and TDD systems, then system simplicity and ease of operation are improved, but reliability deteriorates due to packet loss during flexible resource scheduling
Solution Approach 1:
The patent applies dynamics by transitioning from fixed HARQ-ACK feedback timing to dynamic timing indication. The base station sends timing indication information in DCI that dynamically specifies when the terminal should feed back HARQ-ACK, allowing the feedback timing to adapt to flexible resource scheduling while maintaining system reliability even during packet loss scenarios
Solution Approach 2:
The patent changes the timing parameter from a fixed value to a dynamically indicated value. By introducing timing indication information that specifies the target TTI for HARQ-ACK feedback, the system can adjust the feedback timing parameter based on actual scheduling conditions, resolving the contradiction between operational simplicity and reliability
2Adaptability or versatility
If flexible resource scheduling is implemented, then adaptability and versatility are improved, but reliability deteriorates because terminal devices cannot correctly feed back HARQ-ACK information due to incomplete reception of downlink data
Solution Approach 1:
The patent applies preliminary action by having the base station pre-indicate the target TTI for HARQ-ACK feedback in the DCI before the actual feedback occurs. This allows the terminal to know in advance when to send feedback, ensuring correct HARQ-ACK information is transmitted even when packet loss occurs during flexible scheduling, thus maintaining reliability while preserving adaptability
Data Source
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AI summary
Embodiments of this application provide a HARQ-ACK feedback method and apparatus, and relate to the communications field. The method includes: sending, by a network device to a terminal device, at least one piece of downlink data and DCI corresponding to the at least one piece of downlink data; receiving, by the terminal device, the at least one piece of downlink data and the DCI corresponding to the at least one piece of downlink data, where the DCI includes first indication information, and the first indication information indicates a target transmission time interval TTI for transmitting HARQ-ACK feedback information corresponding to the at least one piece of downlink data; generating, by the terminal device based on second indication information, HARQ-ACK feedback information that needs to be fed back in the target TTI, where the second indication information indicates the number of bits of the HARQ-ACK that needs to be fed back in the target TTI; sending, by the terminal device, the generated HARQ-ACK feedback information to the network device in the target TTI; and receiving, by the network device in the target TTI, the HARQ-ACK feedback information fed back by the terminal device, and decoding the HARQ-ACK feedback information based on the second indication information. This resolves a prior-art problem that a terminal device cannot correctly feed back HARQ-ACK feedback information.