Impact of Station‐Keeping Strategies on VSAT Link Performance in GEO Satellites Under Adaptive Coding and Modulation

ABSTRACT The demand for high‐throughput satellite (HTS) services from Geostationary Earth Orbit (GEO) platforms continues to grow, driving the widespread adoption of advanced physical‐layer techniques such as adaptive coding and modulation (ACM). ACM enhances link availability and spectral efficiency by dynamically adapting modulation order and forward error correction (FEC) in response to channel conditions, primarily targeting atmospheric impairments. However, an important and often underrepresented factor in GEO link performance is the impact of satellite orbital motion and station‐keeping dynamics on antenna pointing accuracy. This paper investigates the effect of different station‐keeping strategies on ACM‐based VSAT link performance by comparing a chemically propelled satellite (Sat‐C), and an electrically propelled satellite (Sat‐E). Simulation results show that Sat‐C exhibits average subsatellite point deviations of approximately 0.178°, compared to only 0.055° for Sat‐E, leading to significantly higher pointing losses, particularly in Ka‐band and for large antenna diameters. These variations translate into several decibels of additional link degradation, forcing frequent ACM downgrades from high‐efficiency MODCODs (e.g., 16APSK/32APSK) to more robust modes such as QPSK. The results demonstrate that satellite station‐keeping strategy is not merely an orbital control parameter, but a fundamental determinant of communication system efficiency that must be co‐designed with ACM to realize the capacity of future GEO networks fully.