HARQ-ACK Feedback for Mixed Transmission Time Intervals
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Solution Overview
Problem
In the LTE system, there is a challenge in efficiently feeding back HARQ-ACK information for downlink data channels transmitted at different transmission time intervals, leading to overlapping feedback latencies and potential errors in acknowledging received data.
Innovation Solution
A method where the terminal device detects the presence of downlink data channels in non-overlapping subframes and selects appropriate uplink channels to send HARQ-ACK information, ensuring that each data channel's feedback is properly indicated without overlapping in time domain resources, thereby resolving the issue of overlapping feedback latencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If multiple transmission time intervals are supported to reduce latency and improve user experience, then transmission speed and adaptability are improved, but feedback latency overlap and reliability deteriorate
Solution Approach 1:
The patent segments the feedback process by dividing it into multiple feedback processes, each corresponding to a specific transmission time interval. The terminal device determines which feedback process to use based on the TTI length of the downlink data channel, ensuring that feedback for different TTI lengths are handled separately and do not overlap, thus maintaining reliability while supporting multiple transmission speeds
Solution Approach 2:
The patent implements dynamic adaptation by allowing the terminal device to dynamically select the appropriate feedback process based on the detected TTI length. The system can switch between different feedback latencies (k1 values) depending on whether short TTI or normal TTI is detected, enabling flexible adaptation to varying transmission requirements while avoiding feedback conflicts
2Adaptability or versatility
If dynamic switching between different sTTI lengths is performed to meet different latency requirements, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent creates a universal feedback mechanism where a single uplink control channel can serve multiple feedback processes. The terminal device uses one uplink control channel to feed back HARQ-ACK information for both short TTI and normal TTI by selecting the appropriate feedback process, reducing the need for separate dedicated channels for each TTI type and thereby reducing overall system complexity
Solution Approach 2:
The patent changes the feedback latency parameter (k1) based on the detected TTI length. When short TTI is detected, a shorter k1 value is used; when normal TTI is detected, a longer k1 value is used. This parameter adaptation allows the system to maintain optimal performance across different TTI lengths without requiring complex structural changes
Data Source
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AI summary
The present invention provides a HARQ-ACK information feedback method, a terminal device, a network device, and a communications system. The HARQ-ACK information feedback method includes: performing, by a terminal device, data channel detection on a first downlink subframe; performing, by the terminal device, data channel detection on a second downlink subframe, where the second downlink subframe does not overlap the first downlink subframe in terms of time domain resources; sending, by the terminal device, first HARQ-ACK information to a network device by using a first uplink channel when determining that the first downlink subframe includes a first downlink data channel and that the second downlink subframe does not include a second downlink data channel, where the first HARQ-ACK information is used to indicate a receiving status of the first downlink data channel, and a first length of a time domain resource corresponding to the first downlink data channel is different from a second length of a time domain resource corresponding to the second downlink data channel; and sending, by the terminal device, second HARQ-ACK information to the network device by using a second uplink channel when determining that the first downlink subframe includes the first downlink data channel and that the second downlink subframe includes the second downlink data channel, where the second HARQ-ACK information is used to indicate the receiving status of the first downlink data channel, and a radio resource occupied by the first uplink channel is different from that occupied by the second uplink channel. According to the technical solutions of the present invention, when the network device and the terminal device support a plurality of transmission time intervals, HARQ-ACK information of data channels corresponding to the plurality of transmission time intervals can be fed back.