Resource management research in ethernet passive optical networks

The last decades, we have witnessed different phenomenology in the telecommunications sector. One of them is the widespread use of the Internet, which has brought a sharp increase in traffic, forcing suppliers to continuously expand the capacity of networks. In the near future, Internet will be composed of long-range highspeed optical networks; a number of wireless networks at the edge; and, in between, several access technologies. Today one of the main problems of the Internet is the bottleneck in the access segment. To address this issue the Passive Optical Networks (PONs) are very likely to succeed, due to their simplicity, low-cost, and increased bandwidth. A PON is made up of fiber optic cabling and passive splitters and couplers that distribute an optical signal to connectors that terminate each fiber segment. Among the different PON technologies, the Ethernet-PON (EPON) is a great alternative to satisfy operator and user needs, due to its cost, flexibility and interoperability with other technologies. One of the most interesting challenges in such technologies relates to the scheduling and allocation of resources in the upstream (shared) channel, i.e., the resource management. The aim of this thesis is to study and evaluate current contributions and propose new efficient solutions to address the resource management issues mainly in EPON. Key issues in this context are future end-user needs, quality of service (QoS) support, energy-saving and optimized service provisioning for real-time and elastic flows. This thesis also identifies research opportunities, issue recommendations and proposes novel mechanisms associated with access networks based on optical fiber technologies.Postprint (published version

New dynamic bandwidth allocation algorithm analysis: DDSPON for ethernet passive optical networks

This project aims to present the state of the art in Dynamic Bandwidth Allocation (DBA) solutions, as well as the study and evaluation of one proposal of DBA algorithm: the Distributed Dynamic Scheduling for EPON (DDSPON), which is the UPC contribution to the research in scheduling algorithms for EPON

Approximation of Baker domains and convergence of Julia sets.

Der Ziel dieser Arbeit ist der Hausdorff Konvergenz der Juliamengen zu beweisen, als wir eine Familie von ganzen transzendenten Funktionen, die ein einziges Bakergebiet enthalten, approximieren. Als erstes geben wir eine vollständige dynamische Beschreibung der approximierenden transzendenten Funktionen und zeigen die Existenz von invarianten Gebiete unter der Iterierte. Insbesondere besitzen die approximierenden Funktionen ein Attraktionsgebiet, das gegen das Bakergebiet als Kernel im Sinn von Carathéodory konvergiert. Letztlich beweisen wir Hausdorff Konvergenz auf zwei Wege. Einerseits zeigen wir unter bestimmten Bedingungen der Fatoumenge der Grenzfunktion die Hausdorff Konvergenz der Juliamengen. Anderseits zeigen wir unter verschiedenen Bedingungen der Fatoumenge der Grenzfunktion die Hausdorff Konvergenz der ausgefüllten Juliamengen, die bezüglich der Bakergebiet oder der Attraktionsgebiet definiert sind

Macroprudential FX Regulations: Sacrificing Small Firms for Stability?

La regulación macroprudencial en moneda extranjera puede reducir el riesgo sistémico; sin embargo, se sabe poco acerca de sus consecuencias no deseadas. Propongo un mecanismo teórico en el que el descalce de monedas actúa como un medio para relajar las restricciones crediticias de las pequeñas empresas y muestro que las políticas que gravan los préstamos en dólares pueden aumentar las disparidades financieras entre las pequeñas y las grandes empresas. Para verificar esto empíricamente, estudio la implementación de un encaje macroprudencial en moneda extranjera por parte del Banco Central del Perú. Construyo una base de datos que combina datos confidenciales del registro de créditos bancarios junto con datos a nivel de empresa sobre empleo, ventas, industria y ubicación geográfica para el universo de empresas formalmente registradas. Demuestro que un aumento del 10 % en la exposición bancaria al encaje aumenta significativamente las disparidades en el crecimiento de los préstamos totales entre empresas pequeñas y grandes en 1,6 puntos porcentuales. Cuando se tiene en cuenta la sustitución a préstamos en moneda nacional de diferentes bancos, el efecto en la deuda de las empresas grandes es solo composicional. Usando datos confidenciales del universo de los contratos de derivados en moneda extranjera, muestro que las empresas que se ven más afectadas por la política no están cubiertas a través de estos derivados cambiarios. Finalmente, usando datos de encuestas a nivel de firmas encuentro que esta política tiene posibles implicaciones heterogéneas en los resultados reales de las empresas como inversión y producción.Macroprudential FX regulation may reduce systemic risk; however, little is known about its unintended consequences. I propose a theoretical mechanism in which currency mismatch acts as a means for relaxing small firms’ borrowing constraints, and show that policies taxing dollar lending may increase financing disparities between small and large firms. To verify this empirically, I study the implementation of a macroprudential FX tax by the Central Bank of Peru. I construct a novel dataset that combines confidential credit register data with firm-level data on employment, sales, industry and geographic location for the universe of formally registered firms. I show that a 10% increase in bank exposure to the tax significantly increases disparities in the growth of total loans between small and large firms by 1.6 percentage points. When accounting for firms switching to soles financing from different banks, the effect on large firms’ debt is only compositional. Using a confidential dataset on the universe of FX derivative contracts, I show that firms that are mostly affected by the policy are not hedged through FX derivatives. Additional findings using survey data suggest that this policy has potential heterogeneous implications for firms’ real outcomes

The link between Violence Against Women in public and urban infrastructure: A case study in Corregidora, Mexico

Violence Against Women (VAW) is widespread in Mexico, with approximately 66.1% of women (30.7 million) having experienced at least one incident of VAW in their lifetime (INEGI, 2017a). Using the municipality of Corregidora, in the state of Querétaro, Mexico, as a case study, this research sought to explore the routine experiences of VAW in the public space to understand the link between public and urban infrastructure and the perpetration of this violence. A mixed methods approach was taken, which combined 272 household surveys (HHS) and 7 focus group discussions (involving 50 women). It was found that the most common type of VAW women experienced in the public sphere, as well as the most recurrent, was catcalling or hearing offensive or sexual remarks including whistling. The following 4 most common types of VAW were fear of being sexually abused, stalking, groping and public indecent exposure. Additionally, the younger women were, the more violence they seemed to experience. Heat maps were generated based on HHS data to identify areas in the urban public space where incidents of VAW took place. These maps were used to select specific high concen- tration locations to conduct structured observations and inductive visual analysis at street level to identify situational factors that might influence the perpetration of VAW in those locations. The key features identified linked to the facilitation of opportunities for the perpetration of VAW included lack of infrastructure, presence of physical obstacles, poor visibility and restricted pedestrian mobility (Garfias Royo et al., 2020). Finally, semi-structured interviews with local government agents revealed challenges to the provision of security to women in public spaces including lack of gender protocols for planning and delivering infrastructure, as well as limited collection and access to crime data. It was also found that the government assists in the creation of gated communities, resulting in a fragmented city

Assessment of groundwater exploitation and land subsidence development in the Toluca aquifer system, Mexico

EbookRegional land subsidence accompanying groundwater abstraction in the Toluca aquifer-system is a challenge for managing groundwater resources and mitigating associated hazards. In order to improve this situation, groundwater management scenarios for the Toluca Valley are examined with a three dimensional groundwater flow model coupled to a one dimensional compaction module. Subsequently, the land subsidence evolution was investigated by integrating SAR interferometry and geological and hydrogeological data to shed insight on the underlying processes governing subsidence. The results indicate that continuing at current rates of water consumption will lead to subsidence of more than 1.6 m over a 40 year period (2010–2050). Completely stopping exports to Mexico City is not the most important factor in controlling subsidence because the pumping system is mostly located in regions with low clay content, where subsidence is lower. However, decreasing exports by half and relocating the pumping centres to low-clay-content areas does have a positive effect on the overall water budget and subsidence. From 2003 to 2016, groundwater level declines of up to 1.6 m/yr, land subsidence up to 77 mm/yr, and major infrastructure damages are observed. Groundwater level data show highly variable seasonal responses according to their connectivity to recharge areas. However, the trend of groundwater levels consistently range from −0.5 to −1.5 m/yr regardless of the well location and depth. By analysing the horizontal gradients of vertical land subsidence, we provide a potential ground fracture map to assist in future urban development planning in the Toluca Valley. The approach taken in this study could be applied to their locations with similar problems in order to determine the most viable option for water supply.CONACyT, Institute for Groundwater Research, University of Guelph UAE