Hybrid HARQ Scheduling for Long-RTT NTN Throughput
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Solution Overview
Problem
Existing wireless communication systems, particularly eMTC and NB-IoT, experience HARQ stalling due to long Round Trip Times (RTTs) in Non-Terrestrial Networks (NTNs), which is exacerbated by the assumption that all HARQ processes require feedback, leading to inefficiencies and stalling when waiting for acknowledgments.
Innovation Solution
Implement multi-TB scheduling that combines feedback-enabled and feedback-disabled HARQ processes, allowing simultaneous transmission and acknowledgment only for feedback-enabled processes, with dummy bits or placeholders for feedback-disabled processes, to reduce stalling and optimize communication efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all HARQ processes are treated as feedback-enabled, then reliability is improved through acknowledgment mechanisms, but productivity deteriorates due to HARQ stalling in NTN environments with long RTTs
Solution Approach 1:
The patent segments HARQ processes into two distinct types: feedback-enabled HARQ processes and feedback-disabled HARQ processes. This segmentation allows the system to treat different HARQ processes differently based on their specific requirements, resolving the contradiction by applying feedback mechanisms only where necessary while maintaining continuous transmission capability where feedback would cause stalling.
Solution Approach 2:
The patent applies local quality by making the feedback requirement property-specific to each HARQ process rather than applying a uniform feedback-enabled approach to all processes. Each HARQ process is configured with appropriate feedback characteristics locally, allowing feedback for processes where it improves reliability while disabling feedback for processes where it would cause stalling in NTN environments.
2Reliability
If feedback-enabled HARQ processes are used for all TBs, then acknowledgment reliability is improved, but communication efficiency deteriorates due to waiting for acknowledgments in long RTT environments
Solution Approach 1:
The patent segments TBs into two categories: those requiring feedback (feedback-enabled HARQ processes) and those that do not require feedback (feedback-disabled HARQ processes). This allows the system to maintain communication efficiency for NTN environments by disabling feedback for TBs where long RTTs would cause stalling, while still providing acknowledgment reliability for TBs where feedback is beneficial.
Solution Approach 2:
The patent changes the feedback parameter configuration based on the specific characteristics of each HARQ process and TB. By dynamically adjusting whether feedback is enabled or disabled for each process, the system optimizes the balance between acknowledgment reliability and communication efficiency according to the operational context and environment.
3Productivity
If multi-TB scheduling combines feedback-enabled and feedback-disabled HARQ processes, then productivity is improved by reducing stalling, but device complexity increases due to differentiated process management
Solution Approach 1:
The patent implements a universal HARQ process management framework that can handle both feedback-enabled and feedback-disabled processes through a single unified mechanism. The base station and UE maintain a unified view of all HARQ processes, managing them through common scheduling procedures while accommodating the different feedback requirements of individual processes, thereby reducing overall system complexity.
Solution Approach 2:
The patent introduces feedback-disabled HARQ processes as an intermediary category between completely feedback-enabled processes and completely feedback-disabled processes. This intermediary approach allows gradual transition and simplified management by providing a middle ground that maintains some level of process control while eliminating the need for complex feedback handling in NTN environments.
Data Source
AI summary
Systems and techniques are provided for wireless communications. For example, an apparatus (e.g., a user equipment (UE)) may receive a plurality of downlink communications, wherein each downlink communication is associated with a Hybrid Automatic Repeat Request (HARQ) process. The apparatus may determine one or more uplink communications, wherein each uplink communication includes feedback associated with at least one downlink communication of the plurality of downlink communications. The apparatus may transmit the one or more uplink communications based on an uplink communication transmission configuration, wherein the uplink communication transmission configuration is determined based on a type of each downlink communication of the plurality of downlink communications.