Performance Analysis of LEO-Terrestrial Systems in Presence of Doppler Effect
A new stochastic geometry model reveals how residual Doppler shift degrades satellite network coverage even after compensation.
A team of researchers has published a critical analysis highlighting a fundamental challenge for next-generation satellite internet. In their paper "Performance Analysis of LEO-Terrestrial Systems in Presence of Doppler Effect," Islam M. Tanash, Nuria Gonzalez-Prelcic, and Risto Wichman employ a novel stochastic geometry-based model to quantify how the Doppler effect—the change in signal frequency caused by the high-speed motion of Low Earth Orbit (LEO) satellites—degrades network performance. Their work focuses on Orthogonal Frequency-Division Multiple Access (OFDMA) systems, a common technology for high-speed data, and shows that even after standard Doppler compensation, a "residual" shift remains. This residual Doppler breaks the orthogonality between subcarriers, causing inter-carrier interference that directly reduces the coverage probability for ground terminals.
The researchers' model explicitly captures this geometry-induced interference by accounting for the spatial distribution of users within a satellite's coverage cell. They validated their analytical framework through extensive Monte-Carlo simulations for both S-band and Ka-band frequencies, confirming the high accuracy of their Doppler shift approximation and coverage probability expressions. The results underscore a non-trivial finding: the impact of residual Doppler is significant and persistent. This means that for companies like SpaceX (Starlink), Amazon (Project Kuiper), and OneWeb building massive LEO constellations, simply compensating for the bulk Doppler shift is insufficient. The study emphasizes that mitigating this residual effect is a necessity, not an option, for designing reliable, high-performance global satellite networks capable of delivering consistent broadband speeds to moving users on land, sea, and air.
- The paper introduces a novel stochastic geometry model to analyze residual Doppler shift in LEO satellite OFDMA networks, a first-of-its-kind analytical approach.
- Key finding: Even after standard compensation, residual Doppler causes inter-carrier interference, significantly reducing network coverage probability, as validated by Monte-Carlo simulations for S-band and Ka-band.
- The work provides a crucial design framework, proving that future LEO network engineers must account for this effect to ensure reliable global broadband service.
Why It Matters
This research provides the mathematical backbone needed to build reliable, high-speed global satellite internet, directly impacting Starlink, Kuiper, and future 6G non-terrestrial networks.