HARQ Feedback Switching Between Carriers in 5G TDD Systems
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Solution Overview
Problem
In ultra-reliable and low latency communication (URLLC) systems, especially in 5G, the frequent feedback of hybrid automatic repeat request (HARQ) acknowledgments (ACKs) is challenging due to limited uplink resources in time division duplex (TDD) systems, leading to a high discard rate of HARQ-ACKs.
Innovation Solution
A method and apparatus for a terminal device to switch between delayed feedback on a current carrier and feedback on a switched candidate carrier, based on a switching priority, to ensure reliable and efficient transmission of HARQ feedback information, avoiding discards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If delayed feedback on current carrier is used, then feedback transmission is simple, but feedback reliability deteriorates due to resource conflicts
Solution Approach 1:
The terminal dynamically switches between first feedback mode (delayed feedback on current carrier) and second feedback mode (feedback on another carrier) based on whether uplink resources on the current carrier are available. This dynamic adaptation resolves the contradiction by selecting the appropriate feedback mode according to real-time resource conditions, ensuring both simplicity and reliability.
2Reliability
If feedback on switched candidate carrier is used, then feedback reliability is improved, but device complexity increases
Solution Approach 1:
The system implements dynamic mode switching where the terminal can operate in first feedback mode (simple, delayed feedback on current carrier) when resources are available, and switch to second feedback mode (reliable, feedback on another carrier) when resources are conflicted. This dynamic approach balances reliability improvements with complexity management.
3Reliability
If frequent HARQ feedback is transmitted, then communication reliability is improved, but uplink resource exhaustion occurs
Solution Approach 1:
The patent introduces a carrier switching mechanism as an intermediary solution. When uplink resources on the current carrier are exhausted, the terminal switches feedback transmission to another carrier, thereby maintaining frequent HARQ feedback transmission (improving reliability) without exhausting the uplink resources of any single carrier.
4Quantity of substance
If HARQ feedback is discarded due to resource limitations, then uplink resource consumption is reduced, but communication efficiency deteriorates
Solution Approach 1:
The patent extends the feedback transmission from a single carrier dimension to multiple carrier dimensions. When uplink resources on the current carrier are limited, the terminal switches to another carrier for feedback transmission, thereby maintaining communication efficiency (avoiding feedback discards) while managing uplink resource consumption across multiple carriers.
Data Source
AI summary
A method for sending a hybrid automatic repeat request (HARQ) includes receiving downlink data, generating HARQ feedback information based on the downlink data, and sending, based on a switching priority, the HARQ feedback information by using a first feedback mode or a second feedback mode. The first feedback mode is delayed feedback on a current carrier, the second feedback mode is feedback on a candidate carrier, and a terminal device supports switching between the first feedback mode and the second feedback mode.