Optimization in VHTS Satellite System Design with Irregular Beam Coverage for Non-Uniform Traffic Distribution

Very High Throughput Satellites (VHTS) have a pivotal role in complementing terrestrial networks to increase traffic demand. VHTS systems currently assume a uniform distribution of traffic in the service area, but in a real system, traffic demands are not uniform and are dynamic. A possible solution is to use flexible payloads, but the cost of the design increases considerably. On the other hand, a fixed payload that uses irregular beam coverage depending on traffic demand allows maintaining the cost of a fixed payload while minimizing the error between offered and required capacity. This paper presents a proposal for optimizing irregular beams coverage and beam pattern, minimizing the costs per Gbps in orbit, the Normalized Coverage Error, and Offered Capacity Error per beam. We present the analysis and performance for the case study and compare it with a previous algorithm for a uniform coverage area

Forward Link Optimization for the Design of VHTS Satellite Networks

The concept of geostationary VHTS (Very High Throughput Satellites) is based on multibeam coverage with intensive frequency and polarization reuse, in addition to the use of larger bandwidths in the feeder links, in order to provide high capacity satellite links at a reduced cost per Gbps in orbit. The dimensioning and design of satellite networks based on VHTS imposes the analysis of multiple trade-offs to achieve an optimal solution in terms of cost, capacity, and the figure of merit of the user terminal. In this paper, we propose a new method for sizing VHTS satellite networks based on an analytical expression of the forward link CINR (Carrier-to-Interference-plus-Noise Ratio) that is used to evaluate the trade-off of different combinations of system parameters. The proposed method considers both technical and commercial requirements as inputs, including the constraints to achieve the optimum solution in terms of the user G/T, the number of beams, and the system cost. The cost model includes both satellite and ground segments. Exemplary results are presented with feeder links using Q/V bands, DVB-S2X and transmission methods based on CCM and VCM (Constant and Variable Coding and Modulation, respectively) in two scenarios with different service areas

Cooperative Multi-Agent Deep Reinforcement Learning for Resource Management in Full Flexible VHTS Systems

Very high throughput satellite (VHTS) systems are expected to have a huge increase in traffic demand in the near future. Nevertheless, this increase will not be uniform over the entire service area due to the non-uniform distribution of users and changes in traffic demand during the day. This problem is addressed by using flexible payload architectures, which allow the allocation of payload resources flexibly to meet the traffic demand of each beam, leading to dynamic resource management (DRM) approaches. However, DRM adds significant complexity to VHTS systems, so in this paper we discuss the use of one reinforcement learning (RL) algorithm and two deep reinforcement learning (DRL) algorithms to manage the resources available in flexible payload architectures for DRM. These algorithms are Q-Learning (QL), Deep Q-Learning (DQL) and Double Deep Q-Learning (DDQL) which are compared based on their performance, complexity and added latency. On the other hand, this work demonstrates the superiority a cooperative multiagent (CMA) decentralized distribution has over a single agent (SA)

Depredación de Pselliopus latispina (Hemiptera: Reduviidae) sobre Tetranychus urticae (Acari: Tetranychidae)

Se reporta la capacidad depredadora de Pselliopus latispina Hussey (Hemiptera: Reduviidae) sobre el ácaro de dos manchas Tetranychus urticae Koch (Acari: Tetranychidae), bajo condiciones de laboratorio. Se utilizaron ninfas de P. latispina de primer instar, provenientes de masas de huevos recolectadas en la Sierra de Álvarez, San Luis Potosí, sobre árboles de cedro blanco Juniperus flaccida Schltdl. (Cupressaceae) y hembras adultas de T. urticae desarrolladas en plantas de frijol Phaseolus vulgaris L. (Fabaceae), originadas a partir de recolectas en huertas de manzana Malus domestica Borkh. (Rosaceae) de Huachichil, Arteaga; Coahuila. Se colocaron ninfas individuales de P. latispina con 50 hembras adultas de T. urticae en cajas Petri, con la finalidad de observar el comportamiento depredador de las ninfas sobre el ácaro. Los datos de depredación fueron analizados con ANOVA y separación de medias mediante pruebas de rango múltiple de Tukey. Se observó la depredación a las 8, 16 y 24 horas y se contabilizó la mortalidad de ácaros. La depredación de P. latispina se incrementó proporcionalmente con el tiempo de exposición, con un consumo promedio de 20, 37 y 48 ácaros a las 8, 16 y 24 horas respectivamente, brindando una nueva opción de manejo del ácaro de dos manchas

Convolutional Neural Networks for Flexible Payload Management in VHTS Systems

Very high throughput satellite (VHTS) systems are expected to have a large increase in traffic demand in the near future. However, this increase will not be uniform throughout the service area due to the nonuniform user distribution, and the changing traffic demand during the day. This problem is addressed using flexible payload architectures, enabling the allocation of the payload resources in a flexible manner to meet traffic demand of each beam, leading to dynamic resource management (DRM) approaches. However, DRM adds significant complexity to the VHTS systems, which is why in this article, we are analyzing the use of convolutional neural networks (CNNs) to manage the resources available in flexible payload architectures for DRM. The VHTS system model is first outlined, for introducing the DRM problem statement and the CNN-based solution. A comparison between different payload architectures is performed in terms of DRM response, and the CNN algorithm performance is compared by three other algorithms, previously suggested in the literature to demonstrate the effectiveness of the suggested approach and to examine all the challenges involved

Compact In-Rack Dielectric Immersion Cooling System

The Compact Dielectric Cooling team consisting of Josh Hannaman, Marshall Reid, and Salvador Landeros worked with Aria Technologies to create a thermal management system for data centers that can easily implement liquid cooling into current infrastructure for high density computing servers. The project was to design, build, and test a compact immersion cooling system for a senior project at California Polytechnic State University – San Luis Obispo. Immersion cooling is a liquid-cooling process that involves the immersion of electrical IT equipment and the removal of heat from the hot IT components using dielectric liquid. The goal was to build a proof of concept that has the potential to be scaled to have 50 kW of cooling capacity per server rack at full-scale. This report consists of technical background information on pumps, heat exchangers, dielectric fluids, IT housing equipment, and liquid cooling solutions that are currently on the market. This report outlines Aria Technologies\u27 specifications and requirements while displaying our design process taken and the design decisions that have been made to meet these said requirements. The design of the compact dielectric cooling system consists of a 1/3 horsepower centrifugal pump that will run between 0.75 and 1.5 gallons per minute while overcoming a system head of about 20 feet. The heat exchanger is a stainless-steel, liquid-to-air heat exchanger that is rated up to a maximum cooling capacity of 1230 watts with a maximum flow rate of 2 gallons per minute. The medium in which the heat is transferred from the IT equipment and into the ambient air is Fluid Manufacturer’s Fluid C synthetic hydrocarbon which is a single-phase dielectric fluid. The chassis where the IT equipment would reside, and the sensible heat transfer takes place was manufactured out of ½” polycarbonate sheet. The cable/chassis interface was designed with CAD and 3D printed with polylactic acid (PLA). All the major system components are connected using 10-millimeter inner diameter fluorinated ethylene-propylene (FEP) tubing and 3/8-inch NPT stainless steel pipe. The final verification prototype system dimensions and specifications are designed for the DELL R6515 server. The two main tests completed on the verification prototype were a cooling capacity at steady state temperature test and a system pressure vs flowrate test

Análisis de la eficiencia de los estándares de transmisión de televisión digital por satélite en las bandas Ku y Ka

ResumenEn este artículo se lleva a cabo un análisis de las principales características técnicas de los estándares para la transmisión de televisión digital por satélite. Con base en simulaciones y cálculo de enlaces se determina el estándar con mejor desempeño operativo y se realiza una comparación de la eficiencia para transmisiones en las bandas Ku y Ka con transpondedores transparentes y regenerativos, en términos de potencia, ancho de banda, tasa de información y margen del enlace, tanto a cielo despejado, como con lluvia en el enlace ascendente, en el descendente y en ambos.AbstractIn this paper, an analysis on the main technical features of digital television standards for satellite transmission is carried out. Based on simulations and link budgets, the standard with the best operational performance is defined, based on simulations and link budget analysis, as well as a comparative efficiency analysis is conducted for the Ku and Ka bands for both transparent and regenerative transponders in terms of power, bandwidth, information rate and link margin, including clear sky, uplink rain, downlink rain and rain in both