Inter-Satellite LED-Based Optical Wireless Communications for CubeSats

This study presents a detailed performance analysis of light-emitting diode (LED)–based optical wireless communication (OWC) systems for inter-satellite communication (ISC) in CubeSat constellations. Motivated by the stringent size, mass, and power constraints of small satellites, we investigate realistic system limitations, including LED modulation bandwidth, optical beam divergence, and environmental background noise from solar, lunar, and terrestrial sources. Analytical and simulation-based bit error rate models are developed for multiple modulation schemes, namely on-off keying (OOK), M-ary pulse position modulation (M-PPM), multiband carrierless amplitude and phase (m-CAP) modulation, and direct current-biased optical orthogonal frequency-division multiplexing (DCO-OFDM). The proposed models consistently embed LED bandwidth limitations, inter-symbol interference, and realistic background-induced shot noise into all four modulation formats, and are validated against independent waveform-level Monte Carlo simulations. The results identify optimal operating regimes for each scheme based on data rate and power constraints, highlighting m-CAP as a strong candidate for high-throughput links and M-PPM for ultra-low-power telemetry. In particular, we quantify non-trivial design boundaries in terms of required Eb/N0 andtransmit power versus data rate, range, and background conditions, and show that, even under an intentionally optimistic avalanche photodiode model, PIN receivers remain more power efficient for the considered CubeSat LED links. Additionally, we quantify the influence of beamwidth and receiver field-of-view on alignment sensitivity and noise resilience. Our findings demonstrate that LED-based OWC can provide scalable, energy-efficient and spectrally agile ISC links, enabling robust communication within next-generation CubeSat missions