HARQ Feedback Timing Determination for TDD Frame Structures
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Solution Overview
Problem
The existing LTE systems face challenges in determining optimal Hybrid Automatic Repeat Request (HARQ) feedback timing, especially with the introduction of shorter Transmission Time Intervals (TTIs), which affects latency and efficiency in TDD frame structures due to varying uplink and downlink configurations and subframe configurations.
Innovation Solution
A method to determine HARQ feedback timing based on TDD UL/DL configuration, TTI length, and special subframe configuration, which involves determining the relative position association between data transmission TTIs, initial transmission TTIs, and retransmission TTIs to ensure timely and efficient HARQ feedback, even distribution of feedbacks across TTIs, and compliance with preset feedback retransmission time associations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If shorter TTI is used to reduce latency, then transmission delay is reduced, but HARQ feedback timing determination becomes more complex due to varying TDD configurations
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting HARQ feedback timing parameters (k values) based on TTI length and TDD configuration. Different TTI lengths (1ms, 0.5ms, shorter TTIs) have different associated k values that determine feedback timing, allowing the system to adapt to varying transmission time requirements while maintaining proper HARQ operation
Solution Approach 2:
The patent implements dynamics by making HARQ feedback timing flexible rather than fixed. The feedback timing is dynamically determined based on the actual TTI length and TDD uplink-downlink configuration, allowing the system to adapt to changing network conditions and configuration requirements while supporting low-latency transmission
2Ease of operation
If fixed feedback time interval is used for FDD, then HARQ feedback timing is simple and deterministic, but it cannot be applied to TDD with varying uplink-downlink configurations
Solution Approach 1:
The patent achieves universality by creating a unified HARQ feedback timing determination method that works across multiple TDD configurations (0-6) and different TTI lengths. The same basic principle of determining feedback timing based on transmission TTI and applying appropriate k values applies universally regardless of specific configuration, making the system adaptable to various network scenarios
Solution Approach 2:
The patent uses parameter changes to adapt the fixed FDD timing concept to variable TDD configurations. By introducing configuration-dependent k values that adjust the feedback timing offset based on the specific TDD uplink-downlink configuration and TTI length, the system maintains the simplicity of deterministic timing while achieving versatility across different configurations
3Productivity
If HARQ feedback timing is optimized for low latency, then transmission efficiency improves, but resource allocation becomes more challenging with multiple TTI lengths
Solution Approach 1:
The patent applies segmentation by dividing the resource allocation into separate handling for different TTI lengths. Each TTI length (1ms, 0.5ms, shorter TTIs) has its own associated k values and timing relationships, allowing the system to optimize feedback timing for each segment independently while maintaining overall system coordination and resource management
Data Source
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AI summary
Provided are a method and apparatus for determining a feedback time sequence of a hybrid automatic repeat request. The method comprises: determining a configuration of a currently used TDD frame structure, wherein the configuration of the TDD frame structure comprises uplink and downlink configurations and a special sub-frame ratio; determining the size of a currently used transmission time interval (TTI); and according to the configuration of the TDD frame structure and the size of the TTI, determining a relative position relationship between a data transmission TTI and a feedback TTI thereof in a HARQ process, or a relative position relationship between an initial transmission TTI, a feedback TTI and a retransmission TTI. Further disclosed are a communication device and a storage medium.