NTN HARQ Virtual Process Mapping for Long Round-Trip Delays
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Solution Overview
Problem
The large number of HARQ processes in non-terrestrial networks, particularly in systems with long round trip times, leads to significant memory requirements, signaling overhead, and additional propagation delays due to HARQ retransmissions, which are not effectively addressed by existing technologies.
Innovation Solution
Implementing dynamic and semi-static HARQ disabling based on carrier and service-specific quality of service requirements, using HARQ Virtual Process Identification, and reducing HARQ process numbers through HARQ Virtual Process Numbers to manage HARQ processes efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of HARQ processes is increased to handle long round trip times in non-terrestrial networks, then the reliability of data transmission is improved, but the memory requirements and device complexity increase significantly
Solution Approach 1:
The patent segments the HARQ process identification into two parts: a small number of HARQ process numbers (0-15) and Virtual HARQ Process IDs. This segmentation allows the system to handle long round trip times by providing multiple Virtual IDs within each process number, effectively increasing the total number of HARQ processes without proportionally increasing memory requirements, as the base process number remains small.
Solution Approach 2:
The patent introduces a new dimension to HARQ process management by adding Virtual HARQ Process IDs as a secondary identification layer. Instead of simply increasing the single dimension of HARQ process count, the system adds a virtual identification dimension that allows multiple virtual processes to share the same physical process number, thereby increasing capacity without linearly increasing memory demands.
2Reliability
If the number of HARQ processes is increased to accommodate long round trip times, then the coverage and reliability are improved, but the signaling overhead increases
Solution Approach 1:
The patent segments the HARQ identification into process numbers and Virtual IDs, allowing the signaling to carry only the compact process number (4 bits) while the Virtual ID is derived or inferred. This reduces the signaling overhead compared to transmitting full unique identifiers for each HARQ process, while still maintaining the ability to distinguish between multiple concurrent processes.
3Reliability
If HARQ retransmissions are performed frequently to ensure reliable delivery in non-terrestrial networks, then the reliability is improved, but the propagation delays increase
Solution Approach 1:
The patent enables preliminary action by allowing the network to pre-configure multiple Virtual HARQ Process IDs and their associated timing parameters. This pre-configuration allows the system to anticipate and prepare for retransmissions, reducing the actual propagation delay when retransmissions are needed, as the virtual process identification and timing relationships are already established.
Data Source
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AI summary
Various communication systems may benefit from improved HARQ. For example, it may be helpful to improve HARQ in non-terrestrial networks. A method may include receiving at a user equipment a configuration from a network entity. The configuration may include a hybrid automatic repeat request virtual process number. The method may also include receiving at the user equipment a downlink control information from the network entity. The downlink control information may include a hybrid automatic repeat request virtual process identification. In addition, the method may include receiving at the user equipment another downlink control information. The another downlink control information may include the hybrid automatic repeat request virtual process identification. Further, the method may include determining at the user equipment a difference between a timing of a transmission indicated by the downlink control information and another timing of another transmission indicated by the another downlink control information.