Closed-form multicast precoding for satellite flexible payloads

This paper investigates a novel closed-form noniterative precoding technique for multicast multibeam satellite systems. Next-generation satellite systems will be benefited from the flexible use of the satellite resources especially its power flexible allocation among beams. Intending to obtain a low-computational complexity design, we revisit the well-known signal-to-leakage-and-noise ratio design for multicast transmission. Two alternatives are introduced considering both the physical meaning of the ratio and certain multicast channel vector mapping. We observe the benefits of these techniques in satellite flexible payloads. The proposed technique shows a substantial gain compared to the benchmark according to the numerical simulations. Intuitive insights on the precoding behaviour are also presented.This work is funded by Ministry of Science, Innovation and Universities, Spain, under project TERESA -TEC2017-90093-C3-1-R (AEI/FEDER, UE) and by Catalan government under the grant 2017-SGR-01479.Peer ReviewedPostprint (author's final draft

Shared access satellite-terrestrial reconfigurable backhaul network enabled by smart antennas at mm-wave band

© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.5G traffic expectations require not only the appropriate access infrastructure, but also the corresponding backhaul infrastructure to ensure a well-balanced network scaling. Optical fibre and terrestrial wireless backhaul will hardly meet 100% coverage and satellite must be considered within the 5G infrastructure to boost ubiquitous and reliable network utilization. This work presents the main outcomes of SANSA project, which proposes a novel solution that overcomes the limitations of the traditional fixed backhaul. It is based on a dynamic integrated satelliteterrestrial backhaul network operating on the mm-wave band. Its key principles are a seamless integration of the satellite segment into terrestrial backhaul networks; a terrestrial wireless network capable of reconfiguring its topology according to traffic demands; and an aggressive frequency reuse within the terrestrial segment and between terrestrial and satellite segments. The two technological enablers of SANSA are smart antenna techniques at mm-wave and a software defined intelligent hybrid network management. This article introduces these 5G enablers, which permit satellite communications to play a key role in different 5G use cases, from the early deployment of 5G services in sparse scenarios to enhanced mobile broadband in denser scenarios.Peer ReviewedPostprint (author's final draft

Chert from the Vegamián Formation: A new raw-material supply source in the Cantabrian Mountains (NW Spain) during prehistory

This work provides the keys to the mineralogical and geochemical characterization of black chert from the Vegamián Fm. This formation crops out throughout the whole of the Cantabrian Zone (of Palaeozoic age), one of the geological zones of the Cantabrian Mountains (NW Spain). The geographical distribution of this formation is very wide, surfacing in the provinces of León, Asturias, Palencia and Cantabria.This variety of chert had been included within the group generically known as ‘black chert’, a macrogroup including different types of chert that appear in different Palaeozoic formations in the area and which share a characteristic black colour at the macroscopic level. The characterisation presented here has enabled us to distinguish it from other varieties. In this study, Vegamián chert has been divided into two different groups depending on their textural, mineralogical, geochemical and thermal propierties. Type 1, the most suitable for knapping, is characterized by high content in silica (>97%), laminated matrix and, occasionally, ghost of radiolarians.  In addition, the characteristics specific to this chert make it suitable for lithic knapping processes. To confirm its use by prehistoric populations, this chert will be compared to that found in two Mesolithic sites, the caves of La Uña and El Espertín (León, south versant of the Cantabrian Mountains), the raw materials from which are currently under study

The Escalada Formation: Characterization of a potential chert supply source in the Cantabrian Mountains (NW Spain) during prehistory

[EN] A study of the chert nodules found in the Escalada Formation (Carboniferous, Ponga region, Cantabrian Zone) was carried out as a means to characterise a number of lithic raw materials found in several prehistoric sites of the Cantabrian Mountains (NW Spain). This study comprises fieldwork aimed at locating the outcrops and obtaining samples. Some selected samples from two localities were used for both petrological (macroscopic and microscopic analyses from thin sections) and geochemical (X-ray fluorescence and powder diffraction) analysis. The macroscopic study shows a rather homogeneus coloration and a conchoidal fracture although two extreme types of cherts with a variety of intermediate forms can be differentiated according to the matrix composition. The microscopic analysis shows a high heterogeneity in carbonate versus silica percentage and gentle differences in some other features such as type of silica, origin of carbonates, occurrence of organic matter and type of skeletal components. The results of several geochemical analysis suggest that there are not geochemical features neither in the major elements nor in the traces that allows us to clearly distinguish between the analysed samples. All these studies allow us to define the main features of these chert nodules and to establish several types and varieties among them. Those varieties with high percentage of silica and with a more homogeneous matrix are the most suitable samples for knapping. These results together with the study of the geological and geographical location of archaeological sites suggest that the nodules from the Escalada Formation likely were lithic material supply sources used in knapping activities When aiming to demonstrate the use of these materials at archaeological sites the sole macroscopic analysis of the pieces does not suffice; further analyses, such as those involving thin sections, are necessary. The absence of chert from Escalada Formation in some Mesolithic sites in the area was confirmed via these additional analyses.SIThis study was supported by funds from project AF-87 “Análisis de industrias líticas prehistóricas: materias primas y tecnología” of the Vicerrectorado de Investigación (Universidad de León, Spain)

An overview of the Mesolithic in the northwest Atlantic and inland area of the Iberian Peninsula

[EN] This paper reviews the Mesolithic in the northwest Atlantic and inland area of the Iberian Peninsula and it is considered in the overall context of the rest of the Peninsula. The Cantabrian Mountains are the northern boundary of the study area, which excludes the adjoining coastal area. In addition to the geographical, geological and environmental settings, the chronology and human remains are also reviewed, paying special attention to the specific characteristics of each of the main sites. The primary faunal, plant remain, bone and stone industry - including raw material supply, technology and typology - features of the main settlements are also presented. All of the above allow us to discuss the similarities and peculiarities of the Mesolithic of this area in relation to other regions of the Peninsula.S

"Mucientes Chert" in the Northern Iberian Plateau (Spain)

The so-called “Mucientes chert" is a variety that appears in the central area of the Iberian North Plateau, in theDueroBasin. It is widely known in the geological and archaeological literature and its use for knapping was especially important in Prehistory. From a macroscopic point of view it is a nodular chert, with white and very porous cortex, and brown to blackish or beige colour in the inner part.In this work we carried out a more accurate petrographic, mineralogical and chemical characterization of this lithology using SEM, XRD and XRF techniques in samples coming from “Las Canteras” (Mucientes village), a chert outcrop of the “Cuestas” Unit (Vallesian-Aragonian, Miocene Age). Also, we have made a review of its geological occurrence and archaeological distribution areas.  It is intended to sketch the delimitation of the geographical area of occurrence taking into account the geological and archaeological references.

“Mucientes Chert” in the Northern Iberian Plateau (Spain)

[EN] The so-called “Mucientes chert" is a variety that appears in the central area of the Iberian North Plateau, in the Duero Basin. It is widely known in the geological and archaeological literature and its use for knapping was especially important in Prehistory. From a macroscopic point of view it is a nodular chert, with white and very porous cortex, and brown to blackish or beige colour in the inner part. In this work we carried out a more accurate petrographic, mineralogical and chemical characterization of this lithology using SEM, XRD and XRF techniques in samples coming from “Las Canteras” (Mucientes village), a chert outcrop of the “Cuestas” Unit (Vallesian-Aragonian, Miocene Age). Also, we have made a review of its geological occurrence and archaeological distribution areas. It is intended to sketch the delimitation of the geographical area of occurrence taking into account the geological and archaeological references.S

El “sílex” en la Meseta norte: sectores central y noroccidental

p. 27-52En este trabajo se realiza una revisión de los datos disponibles sobre los diferentes tipos de sílex (sílex, chert y radiolaritas) y de algunas pizarras sensu lato utilizados para la talla durante la Prehistoria en el cuadrante Noroeste de la Meseta Norte, entendida como el territorio que abarca toda la cuenca hidrográfica del Duero. Se ha comenzado con una evaluación de la base geológica, mediante trabajos de campo y análisis de las referencias bibliográficas sobre estos tipos de rocas y de las formaciones geológicas de las que pueden proceder. Estas últimas han sido divididas en cuatro áreas fuentes: 1) Zona Cantábrica, constituida por rocas sedimentarias; 2) Zona Centroibérica, formada por rocas metamórficas e ígneas; 3) Materiales paleógenos y neógenos que rellenan la cuenca del Duero; y 4) Las terrazas fluviales cuaternarias de la Cuenca del Duero, cuyos materiales proceden de la erosión, transporte y sedimentación de diversas rocas constituyentes del área fuente 3 y, en menor medida, del área fuente 1. En el siguiente apartado se valoran los datos que, sobre esas materias primas, pueden extraerse de los contextos arqueológicos a lo largo de los distintos periodos prehistóricos. Los estudios disponibles se centran en las siguientes rocas: chert negro (laminado y no laminado), radiolarita, “filitas” (pizarra sensu lato) y el denominado “sílex de Mucientes”. Finalmente, se cruzan los datos obtenidos en los dos apartados anteriores para esbozar una imagen de la gestión de estos recursos líticos a lo largo de la Prehistoria que nos permita apuntar sus áreas de aprovisionamiento, sus estrategias de explotación así como un bosquejo de su circulación por esta región.S