HARQ-ACK Repetition Indication for NTN Random Access Coverage
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Solution Overview
Problem
In non-terrestrial networks, the large distance between satellites/aerial devices and the ground leads to insufficient network coverage, affecting the coverage requirement for hybrid automatic repeat request acknowledgement (HARQ-ACK) feedback during the random access procedure, particularly for messages like Msg.4, resulting in incomplete feedback.
Innovation Solution
A method and apparatus that involve receiving and transmitting first indication information to indicate the number of repetitions for a hybrid automatic repeat request acknowledgement message, using radio resource control (RRC) signaling or downlink control information (DCI) to enhance the HARQ-ACK feedback process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HARQ-ACK feedback is transmitted without repetitions in non-terrestrial networks, then transmission speed is maintained, but coverage capability deteriorates due to large distance between satellites and ground
Solution Approach 1:
The patent implements periodic repetition of HARQ-ACK feedback transmissions over multiple time instances. The network device configures a repetition factor that determines how many times the feedback message is transmitted, ensuring reliable delivery in non-terrestrial networks while managing time consumption through controlled repetition cycles
2Reliability
If the number of repetitions for HARQ-ACK feedback is increased, then coverage capability is improved, but feedback transmission time increases
Solution Approach 1:
The patent introduces dynamic adjustment of the repetition factor based on network conditions, terminal capabilities, and channel quality. The network device can adaptively configure different repetition factors for different terminals or different message types, optimizing the balance between reliability and efficiency rather than using fixed repetition counts
Solution Approach 2:
The patent changes the parameter of repetition factor from a fixed value to a configurable parameter that can be adjusted based on channel conditions, message importance, and terminal requirements. This allows the system to optimize feedback transmission by adjusting the repetition count dynamically to match actual network conditions
3Reliability
If HARQ-ACK feedback uses standard DCI format without repetition indication, then device complexity is reduced, but coverage requirement cannot be met in non-terrestrial networks
Solution Approach 1:
The patent extends the existing DCI format to serve multiple functions: it maintains its original scheduling function while adding the capability to indicate HARQ-ACK feedback repetition factors. By reusing existing DCI structures and adding minimal extension fields, the patent avoids creating entirely new signaling mechanisms, thus limiting the increase in device complexity while achieving coverage enhancement
Data Source
AI summary
An indication method is performed by a terminal. The method includes: receiving first indication information transmitted by a network device, and transmitting a hybrid automatic repeat request acknowledgement message corresponding to a random access message according to the first indication information. The first indication information indicates a number of repetitions for the hybrid automatic repeat request acknowledgement message.