Communication link performance evaluation for geostationary satellite versus low earth orbit satellite network in tropical region

Abstract

Latency is a key performance factor for satellite internet, especially for real-time applications like web browsing, video calls, Virtual Private Network (VPN), and remote access used in rural, maritime, emergency, and military environments. While Geostationary (GEO) High Throughput System (HTS) systems still experience high latency due to their orbital altitude, Starlink’s Low Earth Orbit (LEO) constellation now offers globally available low-latency, high-bandwidth satellite internet. Despite their high-speed benefits, both HTS systems in GEO and LEO are using Ku-band which is highly susceptible to rain-induced signal attenuation, particularly in regions with heavy rainfall such as the tropics and equatorial countries. The rain attenuation at Ku-band not only weakens the radio frequency signals but also increases real time latency in the satellite communication link. This research aims to determine the latency of HTS satellites in LEO and GEO induced by rain and evaluate its performance under heavy rainfall conditions. This study uses real satellite link paid services from Société Européenne des Satellites (SES) operator from Luxembourg, SES-12 a geostationary HTS located at 95° east and Starlink LEO constellation operated by Starlink Services a subsidiary of American space company, SpaceX for rain-induced latency performance assessment. A 1.2m VSAT terminal for SES-12 and a Starlink terminal were installed to measure and record latency continuously for six months at the same location with a collocated rain gauge to measure rainfall rate. Site-specific latency datasets were collected to evaluate the Round Trip Time (RTT) using Ku-band link under various rainfall intensities for both satellite services. The empirical measurements were further developed into rain-induced latency correlations, using power law and logarithmic based equations that directly relate to rainfall rate for both satellite systems. These new relationships capture the nominal and tail latency behaviors, representing the normal operating conditions and the degraded latency performance during severe rain-fade conditions, respectively. The results show that the SES-12 GEO terminal latency ranges from 600 ms to 3,000 ms, while the LEO Starlink terminal maintains a much lower latency between 20 ms and 100 ms. Starlink achieved higher link availability (99.6 %) compared to 94 % for SES-12 in the same tropical environment. The findings indicate that extreme rainfall significantly impacts the GEO link, causing prolonged signal degradation and delay expansion, whereas the LEO link remains less affected due to its low-orbit architecture and dynamic satellite switching capability. Keywords: Low Earth Orbit (LEO), Geostationary Earth Orbit (GEO), Rain-Induced Latency, Ku-Band Satellite Communications, Tropical Regions, Empirical Measurements, Link Availability.