Transparent NTN Feeder Link Slot Mapping
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Solution Overview
Problem
Non-terrestrial networks (NTN) face challenges in efficiently managing the feeder link, particularly in supporting multiple cells with high throughput and robust communication, especially due to limitations in bandwidth and susceptibility to phase noise in high-frequency bands.
Innovation Solution
The solution involves using high-frequency bands with larger subcarrier spacing for the feeder link, while maintaining smaller subcarrier spacing for service links, allowing for wider bandwidth utilization and robustness against channel distortions. This is achieved through precise mapping of feeder link slots onto service link slots, potentially using TDM and FDM techniques, and dynamic power management to optimize resource allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-frequency bands are used for feeder link to increase bandwidth, then bandwidth is improved, but phase noise susceptibility worsens
Solution Approach 1:
The patent changes the subcarrier spacing parameter specifically for the feeder link (making it larger than service link spacing) while operating in high-frequency bands. This parameter adjustment compensates for phase noise effects by reducing the time duration of each OFDM symbol, thereby limiting the impact of phase rotation within symbols. The feeder link uses a different numerology (subcarrier spacing configuration) than service links to optimize performance in high-frequency bands.
Solution Approach 2:
The patent applies different subcarrier spacing configurations to different links locally - larger spacing for feeder link and smaller spacing for service links. This localized optimization allows each link to be tuned according to its specific requirements: feeder link prioritizes phase noise robustness with larger spacing, while service link maintains coverage efficiency with smaller spacing.
2Reliability
If larger subcarrier spacing is used for feeder link to reduce phase noise impact, then phase noise robustness is improved, but time synchronization precision worsens
Solution Approach 1:
The patent shifts the synchronization approach from relying solely on time-domain precision to utilizing frequency-domain properties. By using larger subcarrier spacing, the system creates more distinct frequency bins that can be used for correlation-based synchronization, effectively trading time-domain resolution for frequency-domain distinguishability.
Solution Approach 2:
The patent employs synchronization signals and reference signals transmitted on the feeder link that provide feedback information for timing adjustment. The larger subcarrier spacing creates more pronounced correlation peaks in the frequency domain, enabling more robust timing synchronization through feedback mechanisms that adjust based on received signal quality.
3Device complexity
If transparent architecture is used to avoid hardware modifications, then device complexity is reduced, but processing capability worsens
Solution Approach 1:
The patent designs the transparent HAPS platform to perform multiple functions using the same hardware infrastructure. The platform can simultaneously support both feeder link communication with ground stations and service link communication with user equipment, acting as both a relay node and a coverage extension without requiring separate dedicated hardware for each function.
Solution Approach 2:
The transparent HAPS acts as an intermediary that forwards signals between ground stations and user equipment without full signal processing. It performs frequency conversion and signal relaying, enabling extended coverage while maintaining the processing capability of ground-based network equipment.
Data Source
AI summary
Method including: receiving, on a feeder link, a signal including feeder link slots having a feeder link bandwidth; mapping each of the feeder link slots onto a respective slot-subband in a respective service link slot according to a rule; transmitting, on plural service links, service signals, wherein each of the service signals includes service link slots each including m of the slot-subbands having a same bandwidth; the m slot-subbands do not overlap, are continuous with each other, and cover an entire service link bandwidth of the respective service link slot; wherein the feeder link slots have a feeder link slot duration; the service link slots have a service link slot duration longer than the feeder link slot duration; each of the feeder link slots including respective symbols; each of the slot-subbands includes the symbols of the feeder link slot mapped onto the respective slot-subband.