Slot Aggregation Design for Non-Terrestrial Network Communications
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Solution Overview
Problem
In NTN communications, the long HARQ round trip time leads to increased minimum number of required HARQ processes, resulting in higher soft buffer requirements and increased UE implementation complexity and cost. Additionally, disabling the HARQ feedback mechanism to relax soft buffering requirements can degrade performance.
Innovation Solution
The proposed solution involves designing slot aggregation schemes that allow for higher aggregation levels, such as 12, 16, 24, 32, 48, 64, and using DMRS time bundling to improve channel estimation across slots, thereby reducing the need for increased HARQ processes and soft buffering requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of HARQ processes is increased to meet latency requirements in NTN communications, then the reliability of retransmitted packets is improved, but the soft buffer requirements and UE implementation complexity increase
Solution Approach 1:
The patent segments the transmission process by introducing slot aggregation, where multiple slots are grouped together to form a single transmission unit. This allows the system to maintain fewer HARQ processes while achieving the same reliability through repeated transmissions across aggregated slots, thereby reducing the soft buffer requirements and UE complexity.
Solution Approach 2:
The patent applies partial action by transmitting data multiple times across aggregated slots without requiring full HARQ feedback for each transmission. This partial feedback mechanism reduces the burden on the UE's soft buffer while still achieving the necessary reliability through the repeated transmissions inherent in slot aggregation.
2Device complexity
If the HARQ feedback mechanism is disabled to relax soft buffering requirements, then the UE complexity is reduced, but the transmission reliability deteriorates
Solution Approach 1:
The patent merges multiple slot transmissions into a single aggregated transmission unit, allowing the system to achieve diversity gain and improved reliability without requiring separate HARQ feedback for each slot. This combining approach enables relaxed soft buffering requirements while maintaining transmission reliability through the aggregated transmission structure.
3Loss of time
If higher aggregation levels are used in slot aggregation, then the latency requirements are met and soft buffering is reduced, but the channel estimation accuracy across slots becomes more challenging
Solution Approach 1:
The patent employs feedback mechanisms where channel estimation results from reference signals in aggregated slots are utilized to improve the accuracy of channel estimation across the entire aggregation. This feedback loop allows the system to maintain high measurement precision even at higher aggregation levels by leveraging information from multiple slots.
Data Source
AI summary
Various solutions for slot aggregation design in non-terrestrial network (NTN) communications with respect to user equipment and network apparatus in mobile communications are described. An apparatus may receive a demodulation reference signal (DMRS) time bundling configuration. The apparatus may determine a duration interval of the DMRS time bundling configuration. The apparatus may perform phase continuity cross slots of same aggregated slots transmitted in the NTN communications based on the duration interval.