## 2 Related Work  
Starting from the early 1980s, a great number of works has been published in the literature regarding the study of channel models for LMS scenarios. For communication on LMS links, an adequate understanding of the different phenomena and impairments that affect satellite signal propagation in scenarios where mobile terminals are moving around is necessary. For what concerns the signal propagation, different phenomena such as reflection, scattering, diffraction, and multipath phenomena are to take into account in order to model a precise and real satellite channel model. In order to consider the correct statistical formulation, a classification of the communication environment is normally in urban, suburban, and rural scenarios. The main difference between fixed (FMS) and mobile satellite systems (MSS) is that the elevation angle of MSS is much larger, and this affects significantly the QoS received by mobile terminals. Some of the most important publications in the literature regard studies of about forty years ago. One of the first studies on land mobile satellite communication regards an experiment conducted in order to determine an additional path loss on a free-space loss for LMS communications [9]. A statistical model for scenarios of land mobile satellites is provided by [PERSON] in [10]. In this paper, the author provides a model for land mobile satellite communications in a LoS for most of the time and assumes that a lognormal distribution governs the LoS component under attenuation due to foliage (shadowing) and Rayleigh distribution for the multipath component. During the years since, a lot of papers have been proposed on satellite channel models and the common line of all these works is the use of a Markov chain approach that is based on a different number of states, from a two-state model to a multi-state model, that tries to capture the dynamic of the signal and propagation environment. Additionally, in the last years, some researchers have published articles about channel models for satellite communications; for example, in [11], the authors present a three-dimensional channel model at Q-band frequencies modeled by a Markov chain approach, performing experiments on the campus of Heriot-Watt University of Edinburgh. A very recent study [7], showing the synergy between satellite communication and 6G technology, proposes a novel atmosphere data-driven channel model based on artificial neural networks for Q-band frequencies that suffer from different propagation impairments due to high frequencies. In [12], an S-band satellite channel model is proposed in order to deal with the fading characteristic of satellite communication that affects satellite performance. Their simulation experiments, through actual channel measurements, verify the the accuracy of the proposed model. In [13], for the new satellite platform named _Cubesat_, a numerical tool to explore typical irradiation scenarios for CubeSat missions by combining state-of-the-art models is presented. The exploration of these new platforms is of great interest for the scientific communities in the field of wireless communications, and the aspects that concern the channel model are also to be investigated. In the next sections, after presenting the main satellite characteristics and phenomena, the main LMS channel models proposed in the literature are described. Our current research work's main motivation originates from the importance of studying land mobile satellite channel models in order to design an adequate channel model so as to guarantee optimal satellite performance in an overall network scenario. This research study aims to provide a brief and comprehensive review of the main satellite channel models in land scenarios in order to give to the researchers a survey document that comprises the main land mobile satellite channels proposed in the last four decades.