Abstract

Accurate channel modeling is crucial for optimizing direct-to-satellite Internet of things (DtS-IoT) communications via low Earth orbit (LEO) nanosatellites. Traditional channel models for land-mobile satellite systems often overlook the significant impact of shadowing at low elevation angles, limiting their applicability to DtS-IoT scenarios. This paper presents an enhanced finite-state Markov channel with two-sectors (FSMC-TS) model that integrates shadowing effects into the bad sector (B-Sector) by using the K-distribution for modeling. This enhancement captures the combined effects of multipath fading and shadowing, providing a more accurate representation of the channel conditions experienced in DtS-IoT applications. Simulation results show that the enhanced model aligns closely with analytical bit error rate (BER) predictions, particularly at higher signal-to-noise ratios (SNRs), with less than 1% deviation from theoretical values. The Enhanced FSMC-TS model offers a valuable tool for reliable DtS-IoT communication systems, addressing a critical gap in existing channel modeling approaches. © 2025 The Authors