Dynamic HARQ Feedback Timing in TDD Frame Reconfiguration
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Solution Overview
Problem
The existing downlink Hybrid Automatic Repeat Request (HARQ) feedback mechanisms in LTE systems operating in unlicensed frequency bands face challenges in adapting to sudden changes in uplink and downlink service ratios, leading to inefficient resource utilization and reduced frequency spectrum efficiency due to static subframe configurations.
Innovation Solution
A downlink HARQ feedback method based on a dynamic frame structure is introduced, where the frame structure is dynamically reconfigured to optimize subframe allocation, ensuring that each downlink subframe has a corresponding uplink subframe for HARQ feedback, maximizing time-frequency resource utilization and maintaining a stable transmission sequence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a static subframe configuration is used in TDD mode, then the system structure is simple and easy to implement, but the resource utilization efficiency deteriorates when uplink and downlink service ratios change suddenly
Solution Approach 1:
The patent applies dynamic TDD configuration by allowing the uplink-downlink subframe configuration to change according to actual service conditions. The base station dynamically adjusts the subframe configuration based on uplink and downlink service ratios, transforming the static configuration into a dynamic one that adapts to traffic variations, thereby improving resource utilization efficiency while maintaining manageable system complexity through standardized adjustment procedures
2Productivity
If a dynamic TDD configuration is adopted to adapt to sudden service changes, then the frequency spectrum efficiency is improved, but the timing sequence of downlink HARQ feedback becomes unstable and conflicts occur
Solution Approach 1:
The patent applies preliminary action by pre-defining HARQ feedback timing sequences for different TDD uplink-downlink configurations. When the base station dynamically adjusts the subframe configuration, the terminal can quickly switch to the corresponding pre-defined timing sequence without calculation delays or conflicts. This ensures stable and conflict-free HARQ feedback timing even under dynamic configuration changes
Solution Approach 2:
The patent applies parameter changes by establishing correspondence relationships between different TDD configuration parameters (uplink-downlink subframe allocations) and their associated HARQ feedback timing parameters. When the configuration changes, the system switches to the corresponding timing parameters, ensuring that the HARQ feedback timing remains stable and conflict-free while adapting to dynamic service requirements
3Adaptability or versatility
If asynchronous HARQ is used without considering timing sequence, then the system flexibility is improved, but resource waste occurs due to lack of coordinated timing between first transmission and retransmission
Solution Approach 1:
The patent applies feedback mechanisms by establishing coordinated timing relationships between downlink data transmission and uplink HARQ feedback based on the specific TDD configuration. The system uses feedback information (ACK/NACK) received at predetermined timing to trigger retransmissions at optimized times, ensuring that retransmissions are properly coordinated with the current TDD configuration rather than occurring at arbitrary times, thereby reducing resource waste while maintaining system flexibility
Data Source
AI summary
A downlink Hybrid Automatic Repeat Request (HARQ) feedback method is provided, and includes: determining whether a currently used frame structure needs to be reconfigured; determining an uplink subframe for implementing a downlink HARQ feedback corresponds to each downlink subframe according to the currently used frame structure, when no reconfiguration is needed; determining an uplink subframe for implementing the downlink HARQ feedback corresponds to each downlink subframe in a last radio frame before the reconfiguration time point, when the reconfiguration is needed, according to a first frame structure used before a reconfiguration time point and a second frame structure to be used; determining an uplink subframe for implementing the downlink HARQ feedback corresponds to each downlink subframe in a last radio frame before the reconfiguration time point; when receiving downlink data sent by a base station on any downlink subframe, sending a HARQ feedback message for the downlink data.