NTN Sidelink Resource Selection via Propagation Delay Compensation
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Solution Overview
Problem
In Non-Terrestrial Networks (NTNs), especially in 5G NR sidelink communications between aircraft and vessels, propagation delays cause scheduling conflicts and inefficiencies, leading to increased radio access latency and spectral inefficiency due to the need for slot aggregation and long guard intervals.
Innovation Solution
A scheduler, such as a Physical Sidelink Shared Channel (PSSCH) scheduler, determines candidate radio resources while considering propagation delays to avoid conflicts, selecting resources based on expected signal-to-interference-plus-noise ratio (SINR) and excluding conflicting slots to prevent half-duplex conflicts and optimize beam usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If slot aggregation and long guard intervals are used to handle propagation delays in NTN sidelink communications, then reliability is improved, but latency increases and spectral efficiency deteriorates
Solution Approach 1:
The patent changes the scheduling parameters by introducing propagation delay compensation mechanisms. The gNB calculates adjusted scheduling offsets (K1, K2) that account for the round-trip propagation delay in NTN scenarios, allowing terminals to transmit and receive without requiring additional guard intervals or slot aggregation, thus reducing latency while maintaining reliability
Solution Approach 2:
The patent applies preliminary action by pre-calculating and configuring propagation delay compensation parameters through higher-layer signaling before actual sidelink communications occur. The gNB provides offset values that terminals use in advance to align their transmission and reception timing, preventing conflicts before they arise rather than requiring reactive measures like slot aggregation
2Adaptability or versatility
If slot aggregation is used to handle propagation delays, then scheduling flexibility is improved, but spectral efficiency deteriorates
Solution Approach 1:
The patent modifies scheduling parameters by introducing propagation delay-specific offset adjustments. Instead of aggregating slots, the system changes the timing offset parameters (K1, K2) to compensate for NTN propagation delays, allowing single-slot transmissions that maintain spectral efficiency while achieving the necessary scheduling flexibility through parameter adaptation
3Object-affected harmful factors
If long guard intervals are used to prevent conflicts in NTN sidelink, then interference is reduced, but resource utilization deteriorates
Solution Approach 1:
The patent replaces the mechanical approach of using long guard intervals (time-based separation) with a calculation-based timing adjustment mechanism. The gNB computes precise transmission offsets that account for propagation delays, substituting the need for excessive guard periods with mathematically optimized scheduling that maintains low interference while maximizing resource utilization
4Loss of time
If propagation delay compensation is implemented through scheduling adjustments, then latency is reduced, but scheduling complexity increases
Solution Approach 1:
The patent introduces the gNB as an intermediary that centralizes the complex propagation delay calculations. Rather than requiring each terminal to independently compute and coordinate timing adjustments (which would increase distributed complexity), the gNB performs the calculations and provides simplified offset parameters to terminals, reducing overall system complexity while achieving low latency
Data Source
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AI summary
An apparatus, method and computer program is described comprising: determining a set of candidate radio resources for transmitting data from a first communication node of a non-terrestrial network to a second communication node of the non-terrestrial network over a direct radio link; identifying one or more of the candidate radio resources as conflicting radio resources that conflict with at least one scheduled radio transmission in the non-terrestrial network based, at least in part, on a propagation delay associated with the at least one scheduled radio transmission and/or a propagation delay associated with the radio transmission by the first communication node; generating a subset of candidate radio resources by excluding the identified one or more conflicting radio resources from the set of candidate radio resources; and selecting a radio resource from the subset of candidate radio resources for transmitting the data over the direct radio link.