HARQ Bundling Window for Half-Duplex TDD Feedback
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Solution Overview
Problem
In Rel. 14 based HD TDD MTC systems, there is a need for a method to perform Hybrid Automatic Repeat Request (HARQ) bundling, as existing solutions do not provide clear guidance on how to implement HARQ bundling, leading to conflicts between uplink feedback transmission and downlink data transmission.
Innovation Solution
A method for transmitting HARQ feedback information by determining a HARQ bundling window, where feedback for multiple received data packets is logically operated and transmitted together, allowing for efficient bundling and reduction of conflicts between uplink and downlink transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If one-to-one HARQ feedback is applied in HD MTC system, then feedback accuracy is improved, but transmission conflict occurs between uplink feedback and downlink data
Solution Approach 1:
The patent combines multiple HARQ feedback information bits into a single bundled feedback transmission. Specifically, feedback for multiple downlink subframes (e.g., subframes n-4, n-3, n-2, n-1) are aggregated and transmitted together in uplink subframe n, eliminating the need for separate feedback transmissions that would cause conflicts with downlink data transmissions.
Solution Approach 2:
The patent establishes a periodic bundling pattern where feedback for a specific number of downlink subframes is collected and transmitted at regular intervals in uplink subframes. This periodic structure allows the system to systematically manage feedback transmissions according to the half-duplex constraints, preventing conflicts by synchronizing feedback transmissions with available uplink slots.
2Productivity
If HARQ bundling is applied to avoid transmission conflict, then transmission efficiency is improved, but feedback information loss may occur
Solution Approach 1:
The patent incorporates a downlink assignment indicator (DAI) in the downlink control information that provides feedback to the UE about the number of downlink subframes requiring acknowledgment. This DAI mechanism allows the UE to verify whether it has correctly received and processed all necessary feedback information, enabling detection of any information loss during the bundling process and triggering appropriate retransmission or correction actions.
3Adaptability or versatility
If HARQ bundling window parameters are not specified, then system flexibility is improved, but implementation complexity increases
Solution Approach 1:
The patent defines specific parameter configurations for the HARQ bundling window, including the relationship between downlink subframe indices and uplink feedback subframe indices. By establishing concrete parameter values and relationships (e.g., feedback for subframes n-4 to n-1 transmitted in subframe n), the patent transforms a potentially complex and flexible system into one with well-defined, implementable parameters that reduce ambiguity while maintaining adaptability to different TDD configurations.
Data Source
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AI summary
Disclosed are a method for sending a hybrid automatic repeat request (HARQ) feedback information, a user equipment, and a base station. The method comprises: determining a reception window of data on which HARQ binding is to be performed; detecting data in the reception window; and binding and sending HARQ feedback information of the data detected in the reception window. By means of the method, the user equipment and the base station, HARD binding can be very conveniently implemented in a half-duplex (HD) frequency division multiplexing system.