HARQ-ACK Codebook Handling for Long-RTT Satellite NR
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Solution Overview
Problem
The Hybrid Automatic Repeat Request (HARQ) mechanism in the New Radio (NR) system experiences low user throughput due to the stop-and-wait protocol, which is exacerbated by the large round-trip transmission time (RTT) in satellite communication, limiting the effectiveness of parallel HARQ processes.
Innovation Solution
The HARQ process is configured to be disabled or enabled dynamically, allowing the network device to reuse these processes for data transmission without waiting for acknowledgment, thereby increasing the number of parallel processes and reducing the impact of RTT.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the stop-and-wait protocol is used for HARQ, then transmission reliability is ensured, but user throughput deteriorates due to waiting time
Solution Approach 1:
The patent segments the HARQ process into multiple parallel processes (first HARQ process and second HARQ process). By dividing the single HARQ process into multiple independent processes, the system can simultaneously handle multiple data transmissions without waiting for acknowledgments sequentially, thereby improving throughput while maintaining reliability through the stop-and-wait mechanism within each process.
Solution Approach 2:
The patent enables the network device to preemptively send data using an alternative HARQ process when the current process is waiting for acknowledgment. This preliminary action allows the system to utilize available HARQ processes efficiently, reducing idle waiting time and improving overall throughput without compromising the reliability of the original transmission.
2Productivity
If multiple parallel HARQ processes are used, then user throughput is improved, but the impact of large RTT in satellite communication limits the effectiveness
Solution Approach 1:
The patent dynamically manages HARQ process states by introducing enabled and disabled states. The network device can flexibly switch between different HARQ processes based on RTT conditions, enabling processes that are not waiting for acknowledgments and disabling or skipping feedback for processes with large RTT, thereby adapting to the time loss constraints of satellite communication while maintaining high throughput.
Solution Approach 2:
The patent changes the operational parameters of HARQ processes by configuring them as enabled or disabled. This parameter change allows the system to optimize the number of active parallel processes according to the RTT characteristics, reducing the negative impact of large RTT in satellite communication while preserving the throughput benefits of parallel processing.
3Measurement precision
If the network device waits for HARQ-ACK feedback before reusing the HARQ process, then transmission accuracy is maintained, but data transmission continuity deteriorates
Solution Approach 1:
The patent allows the network device to perform preliminary data transmission using alternative HARQ processes before receiving feedback for current processes. By preemptively utilizing available processes, the system maintains data transmission continuity without waiting for acknowledgments, while still ensuring transmission accuracy through the HARQ mechanism in the alternative processes.
Solution Approach 2:
The patent ensures continuous useful action by enabling the network device to continuously transmit data using enabled HARQ processes without interruption for feedback waiting. The system maintains transmission continuity by switching between multiple processes, ensuring that data transmission never stops even when some processes are waiting for acknowledgments.
Data Source
AI summary
A method for feeding back a hybrid automatic repeat request acknowledgement (HARQ-ACK) and a terminal device. The method comprises: a terminal device receives a first physical channel transmitted by a network device using a first HARQ process, the first HARQ process corresponding to a disabled state; the terminal device generates a first HARQ-ACK codebook, the first HARQ-ACK codebook comprising a first HARQ-ACK feedback bit corresponding to the first physical channel, or, the first HARQ-ACK codebook comprising no first HARQ-ACK feedback bit corresponding to the first physical channel.