Throughput Analysis and On-Board Buffer Sizing for Hybrid RF and Optical LEO Satellites

TL;DR

This paper analyzes throughput and buffer sizing in hybrid RF/laser LEO satellite networks, highlighting the importance of scheduling and buffer management for optimal performance under weather-induced outages.

Contribution

It introduces a comprehensive analysis of throughput performance and buffer sizing strategies in hybrid RF/FSO satellite networks considering interference and weather effects.

Findings

Laser communications significantly improve throughput.

Scheduling priorities can maximize throughput while minimizing buffer needs.

Proper buffer sizing reduces packet loss under operational constraints.

Abstract

Low Earth Orbit (LEO) satellite networks are increasingly adopting laser (Free Space Optics, FSO) links to provide high-capacity communications. Although laser inter-satellite links offer high throughput and low latency, RF up- and downlinks remain necessary to maintain connectivity during optical outages caused by adverse atmospheric conditions. In such hybrid link scenarios, satellite buffer design remains a key challenge, since up- and downlink traffic must be buffered and forwarded among satellite nodes. The hybrid RF/FSO scenario requires careful transmission scheduling, especially at envisioned optical transmission rates of 100Gb/s and beyond, making buffer sizing critical under strict onboard energy and weight constraints. Thus, this paper analyzes throughput performance and buffer sizing in hybrid RF/laser satellite networks with finite buffer capacity, interference-aware scheduling, and weather-dependent laser link outage probabilities. Numerical results indicate that laser communications bring significant performance gains. Instead of increasing the transmission power of the satellite to maximize the throughput, we can select a suitable transmission scheduling priority to achieve a maximum throughput, while minimizing the buffer requirement, and lowering packet loss probability under realistic operational conditions and constraints.