Interference-Aware Satellite Slot Scheduling for Shared Spectrum
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Solution Overview
Problem
Existing wireless communication systems using a shared physical communications medium face interference issues due to overlapping fields of view, leading to inefficient utilization and potential equity problems, especially in low Earth orbit satellite systems where satellites provide transient coverage.
Innovation Solution
A method for scheduling transmissions that involves determining interference parameters, using a slot reservation map, and adjusting slot transmission parameters to minimize interference by selecting optimal transmission times, frequencies, and power levels to avoid reserved slots or geographic regions of other systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple communication systems permanently reserve segments of radio frequency spectrum, then interference between systems is reduced, but utilization efficiency of the shared medium deteriorates
Solution Approach 1:
The system transitions from static permanent spectrum reservations to dynamic temporal reservations where slot allocations change over time based on satellite visibility and system activity. The reservation map is continuously updated to reflect current interference conditions and coverage requirements, allowing efficient utilization when satellites are in view while preventing interference when they are not.
Solution Approach 2:
The system implements periodic updating of the reservation map at scheduled times, allowing systems to alternate usage of frequency slots in a periodic manner. This enables efficient use of the shared medium during periods when no satellite is visible, while maintaining reliable interference-free operation during active communication periods through structured time-division multiplexing.
2Device complexity
If communication systems coordinate spectrum usage at a high level with permanent reservations, then interference management is simplified, but adaptability to temporal usage patterns deteriorates
Solution Approach 1:
The system segments the frequency spectrum into multiple slots and divides time into discrete intervals, creating a structured reservation map that tracks which systems have reservations for which slots at different times. This segmentation allows automated conflict detection and resolution without complex real-time coordination, while maintaining high adaptability to temporal patterns through the time-varying nature of the reservations.
3Productivity
If LEO satellites use shared communication medium with overlapping slots, then resource utilization improves, but interference between systems increases
Solution Approach 1:
The system performs preliminary actions by pre-establishing reservations in the reservation map before actual transmissions occur. When a satellite becomes visible, the system checks the reservation map to determine which frequency slots are already reserved by other systems and avoids those slots, thereby preventing interference before it can occur while still allowing efficient use of available spectrum resources.
Data Source
AI summary
An adaptive satellite communication system uses an interference aware scheduler to select slot transmission parameters for transmitting a message. When scheduling transmission of a message by a particular terminal the scheduler determines interference parameters of any external communication systems for the transmitter location and intended transmission time period. The scheduler then uses this to estimate if a particular combination of slot transmission parameters are likely to cause interference and can then adjust the slot transmission parameters to reduce potential interference. The scheduler may use an optimisation method which is configured to select slots based subject to constraints related to latency, probability of transmission failure/success and interference.