LEO NTN Uplink Scheduling With Zone-Based Delay Offsets
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Solution Overview
Problem
Current scheduling mechanisms in non-terrestrial networks (NTNs) are inadequate for addressing high differential delay, propagation delay, and doppler effects, particularly in low-earth orbit (LEO) satellite systems, leading to increased latency and performance degradation for user equipment (UEs).
Innovation Solution
A zone-based scheduling (ZBS) method is introduced, dividing the coverage area into zones based on differential delay and doppler shift, allocating independent scheduling offsets for each zone, and optimizing uplink resource blocks to mitigate these issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single scheduling offset is used for all UEs in an NTN cell, then the scheduling mechanism is simple to implement, but the latency increases and performance degrades due to high differential delay and doppler effects
Solution Approach 1:
The patent divides the NTN cell into multiple zones based on differential delay and doppler shift characteristics. Each zone is assigned a specific scheduling offset, allowing the system to handle different propagation conditions separately. This segmentation resolves the contradiction by maintaining simplicity within each zone while improving overall latency performance through zone-specific optimization.
Solution Approach 2:
The patent applies local quality by assigning different scheduling offsets to different zones within the NTN cell. Instead of using a uniform scheduling offset for the entire cell, each zone receives a locally optimized scheduling offset that accounts for its specific differential delay and doppler shift characteristics, thereby reducing latency while maintaining manageable complexity.
2Loss of time
If zone-based scheduling with multiple scheduling offsets is implemented, then latency is reduced and performance is improved, but the scheduling mechanism becomes more complex
Solution Approach 1:
The patent segments the NTN cell into multiple zones, each with its own scheduling offset. This segmentation allows the system to reduce latency by optimizing scheduling for each zone's specific conditions, while the modular zone-based structure keeps the increased complexity organized and manageable through clear demarcation of scheduling parameters.
3Device complexity
If uplink resources are allocated without considering differential delay, then resource allocation is simple, but system performance degrades due to propagation delay variations
Solution Approach 1:
The patent applies local quality by allocating uplink resources with zone-specific scheduling offsets that account for differential delay and doppler shift. Each zone receives resource allocation optimized for its local propagation conditions, improving system performance and reliability while maintaining reasonable complexity through the structured zone-based approach.
Data Source
AI summary
The various embodiments herein disclose methods and systems for uplink scheduling schemes for low-earth orbit (LEO) satellite based Non-Terrestrial Network (NTN). According to an embodiment, a zone-based scheduling (ZBS) scheme is described where the coverage area may be divided into a plurality of zones and independent scheduling-offsets may be allocated for each of the zones. The ZBS scheme improves upon the overall user latency by reducing the K2 and cell offset delay for low-propagation delay users within the NTN cells. At the same time, the impact of differential doppler may also be mitigated with such a zone-based allcoation strategy.