Dynamic HARQ Activation in Non-Terrestrial Networks
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Solution Overview
Problem
In non-terrestrial networks, the long distance between user equipment (UE) and satellites leads to significant propagation delays, reducing data transmission rates and complicating HARQ feedback operations, especially due to the limited number of HARQ processes and increased costs associated with additional processes.
Innovation Solution
Implementing a method where the base station transmits HARQ process activation indication information to the UE, allowing it to dynamically determine whether to perform HARQ operations based on information within the downlink signal, and transmitting feedback only when necessary, thereby optimizing HARQ process usage and reducing delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HARQ feedback operation is performed in non-terrestrial network, then communication reliability is improved, but data transmission rate is significantly reduced due to propagation delay
Solution Approach 1:
The patent applies dynamics by making the HARQ feedback operation configurable rather than fixed. The base station can dynamically activate or deactivate HARQ feedback operations through RRC configuration and MAC CE commands, allowing the system to adapt between reliable communication mode (HARQ enabled) and high-speed transmission mode (HARQ disabled) based on current network conditions and service requirements.
Solution Approach 2:
The patent changes the operational parameters of HARQ feedback by introducing activation and deactivation states. Through RRC configuration parameters (harq-FeedbackEnabled) and MAC CE control elements, the system can switch between different HARQ feedback modes, effectively changing the parameter of feedback operation from always-on to conditionally-active, thereby balancing reliability and transmission rate.
2Productivity
If additional HARQ processes are added to compensate for propagation delay, then data transmission rate is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies partial action by enabling HARQ feedback operations only when necessary rather than always. Through selective activation based on RRC configuration and MAC CE commands, the system performs HARQ feedback partially (only for specific transmissions or under specific conditions) rather than excessively (for all transmissions), thereby achieving the needed reliability improvement without the full complexity overhead of always-on HARQ with multiple processes.
3Reliability
If HARQ feedback is always transmitted, then communication reliability is improved, but loss of time due to feedback overhead increases
Solution Approach 1:
The patent implements periodic action by allowing HARQ feedback to be transmitted only at specific intervals or under specific conditions rather than continuously. The base station can configure periodic HARQ feedback operations or trigger them selectively through MAC CE commands, creating a periodic or event-driven feedback pattern that reduces overall feedback overhead time while maintaining reliability for critical transmissions.
Data Source
AI summary
Provided are apparatus and method for communication in a non-terrestrial network (NTN). The method may include: receiving, from a base station, HARQ process activation indication information indicating whether to activate an HARQ process operation; determining whether to perform the HARQ process operation for a downlink signal on the basis of information included in the downlink signal when the downlink signal is received from the base station if the HARQ process operation deactivation is configured by the HARQ process activation indication information; and transmitting, to the base station, feedback information for the downlink signal when performing the HARQ process operation for the downlink signal is determined.