NTN HARQ Feedback Routing for Low-Latency Retransmission
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Solution Overview
Problem
Existing communication networks struggle with significant propagation delays in multi-link environments involving non-terrestrial networks (NTN), where links with large delays are not effectively managed to overcome the disadvantages of links with small delays.
Innovation Solution
A method for transmitting HARQ feedback through a link with small latency and retransmitting data through a link with large latency, utilizing a first and second NTN link with different latency characteristics, and adjusting HARQ feedback and retransmission timing based on QoS and congestion levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If data is transmitted through NTN link with large propagation delay, then coverage area is expanded to non-terrestrial networks, but HARQ feedback timing is significantly delayed
Solution Approach 1:
The patent segments the HARQ feedback path from the data transmission path. Data is transmitted through the NTN link with large propagation delay, while HARQ feedback is transmitted through a separate terrestrial link with small propagation delay. This segmentation allows the system to maintain large coverage area through NTN while avoiding HARQ timing delays by using a different path for feedback.
Solution Approach 2:
The patent introduces a terrestrial communication node as an intermediary for HARQ feedback transmission. The UE sends HARQ feedback to the terrestrial node, which then forwards it to the satellite. This intermediary approach allows HARQ feedback to bypass the long propagation delay of the direct NTN link while still maintaining the expanded coverage area benefit.
2Device complexity
If HARQ feedback is transmitted through the same NTN link as data, then link management is simplified, but retransmission speed is reduced due to large latency
Solution Approach 1:
The patent segments the communication paths: data transmission occurs through the NTN link while HARQ feedback transmission occurs through a separate terrestrial link. This segmentation enables fast retransmission by using the low-latency terrestrial path for feedback, while maintaining relatively simple link management through coordinated resource allocation and timing adjustment between the two links.
3Loss of time
If terrestrial network links are used exclusively, then propagation delay is kept small for fast communication, but coverage area is limited to terrestrial regions
Solution Approach 1:
The patent implements a multi-functional communication system where the UE can communicate through both NTN links (for coverage extension) and terrestrial links (for low-latency feedback). The system universally supports multiple transmission paths, allowing it to achieve both large coverage area through NTN and small propagation delay through terrestrial links for HARQ feedback.
Data Source
AI summary
A method of a first communication node, according to the present disclosure, may comprise the steps of: requesting resource allocation of a second non-terrestrial network (NTN) link between a second communication node and a user equipment (UE) in order to receive hybrid automatic repeat request (HARQ) feedback from the UE through the second communication node; transmitting, through a first NTN link passing through a first satellite, downlink control information (DCI) for the transmission of data to the UE on the basis of an acceptance response to resource allocation of the second NTN link to the UE from the second communication node; transmitting data to the UE through the first NTN link on the basis of the downlink control information; and receiving, from the UE, through the second communication node, an HARQ feedback signal corresponding to the transmitted data.