# State-of-the-Art in Satellite Communication Networks
###### Abstract
In the paper, a genetic algorithm approach is proposed in order to study the dynamic time slot allocation under the effect of time-varying rain attenuation in the context of a DVB-S2X satellite environment where opportune MODCODs can be used in order to obtain optimal spectrum efficiency for each beam in different time slots. The simulation results demonstrate that compared to traditional techniques the proposed dynamic approach is able to better manage time slot allocation, thus guaranteeing an improvement of the overall system performance. [PERSON] et al. [6] studied a cross-layer and cross-dimension radio resource optimization model based on a firefly algorithm that takes into account the channel state information (CSI) and QoS of the satellite communications in a multi-satellite and multi-beam scenario. Their study tries to improve the resource management in the overall system and then obtain high spectrum efficiency throughout a packet segmentation scheme able to map different packets to radio resources. Their simulations show an improvement in the system throughput and in the user satisfaction index. [PERSON] et al. [7] proposed the design of a Tx/Rx multibeam antenna based on a discrete lens integrated with a reflector system. This approach allows a reduction in the active lens's size as well as a reduction in the radiating system's complexity. The Tx/Rx radiating elements have been built and tested. The design procedure's efficiency was demonstrated by the agreement between simulated and measured data. [PERSON] et al. [8] presented a continuously reconfigurable metasurface reflector based on unit cell mushroom geometry that was integrated with a varactor diode able to operate in an optimized manned in an X-band and Ku-band satellite system and improve the quality of service. The authors have designed a unit cell of the metasurface. The losses and dynamic reflection phase range of the unit cell design parameters were investigated. The magnitude and phase reflection of the unit cell are illustrated over a wide frequency spectrum, with good agreement between all the measurements and the simulations. [PERSON] et al. [9] dealt with the use of Ka and Q/V bands for obtaining a high data rate in satellite services. Clearly, at these frequencies, the signal attenuation is an important aspect to take into account. To face with this issue, a micro-scale site diversity system has been proposed and evaluated in terms of capacity gain using rain attenuation time series generated using the Synthetic Storm Technique (SST). A considerable capacity gain can be shown in all of the cases studied, indicating that micro-scale site diversity systems might be a realistic option for corporate users looking to boost data rates and enhance connection availability. [PERSON] et al. [2010] explored the challenges and constraints when the over-the-horizon (OTH) maritime surveillance service utilizes the Internet of Things (IoT) as its backbone. The authors have examined the service performance under various meteorological conditions specific to the Gulf of Guinea. The analysis aims to mathematically describe the impact of harsh weather conditions on the performance of the service. The goodness of the proposed analysis is proven, as demonstrated through the high quality of service with an outage probability of just 0.1%. The work presented by the authors aims to be a sort of guideline for the deployment of maritime surveillance service solutions in other equatorial regions. Finally, [PERSON] et al. [2011] presented a comprehensive review of the most recent developments in satellite channel communications related to mobile services and, in particular, for the land mobile satellite systems. They presented all different types of Markov models, from single-state to multi-state models, that have been proposed in the literature since the early 1980s.