3,307 research outputs found
Layered multicast: A study of loss event rate estimation in a low level of statistical multiplexing
Layered multicast protocol (LMP) uses TCP-equation
model to estimate TCP-compatible rate. One of the most
important parameter of TCP-equation model is loss event rate. It is acquired by estimating the number of packets between two lost events, which is determined by packet-drop pattern at the bottleneck link. In a low level of statistical multiplexing environment packet-drop pattern at the bottleneck link is determined by the queuing management and the behaviours of competing data flows. Since TCP is the dominant protocol of the Internet, the performance of LMP is greatly affected by the behaviours of TCP flows. Since TCP is an aggressive and bursty protocol, competing with TCP results in volatile estimated loss event rate for LMP. Smoothing techniques for loss even rate have been proposed to reduce the volatility of loss event rate. This
paper presents a comparative study of loss event rate smoothing techniques for layered multicast protocol. The study has been conducted in a low level statistical multiplexing environment
InternalBlue - Bluetooth Binary Patching and Experimentation Framework
Bluetooth is one of the most established technologies for short range digital
wireless data transmission. With the advent of wearables and the Internet of
Things (IoT), Bluetooth has again gained importance, which makes security
research and protocol optimizations imperative. Surprisingly, there is a lack
of openly available tools and experimental platforms to scrutinize Bluetooth.
In particular, system aspects and close to hardware protocol layers are mostly
uncovered.
We reverse engineer multiple Broadcom Bluetooth chipsets that are widespread
in off-the-shelf devices. Thus, we offer deep insights into the internal
architecture of a popular commercial family of Bluetooth controllers used in
smartphones, wearables, and IoT platforms. Reverse engineered functions can
then be altered with our InternalBlue Python framework---outperforming
evaluation kits, which are limited to documented and vendor-defined functions.
The modified Bluetooth stack remains fully functional and high-performance.
Hence, it provides a portable low-cost research platform.
InternalBlue is a versatile framework and we demonstrate its abilities by
implementing tests and demos for known Bluetooth vulnerabilities. Moreover, we
discover a novel critical security issue affecting a large selection of
Broadcom chipsets that allows executing code within the attacked Bluetooth
firmware. We further show how to use our framework to fix bugs in chipsets out
of vendor support and how to add new security features to Bluetooth firmware
Inside Job: Diagnosing Bluetooth Lower Layers Using Off-the-Shelf Devices
Bluetooth is among the dominant standards for wireless short-range
communication with multi-billion Bluetooth devices shipped each year. Basic
Bluetooth analysis inside consumer hardware such as smartphones can be
accomplished observing the Host Controller Interface (HCI) between the
operating system's driver and the Bluetooth chip. However, the HCI does not
provide insights to tasks running inside a Bluetooth chip or Link Layer (LL)
packets exchanged over the air. As of today, consumer hardware internal
behavior can only be observed with external, and often expensive tools, that
need to be present during initial device pairing. In this paper, we leverage
standard smartphones for on-device Bluetooth analysis and reverse engineer a
diagnostic protocol that resides inside Broadcom chips. Diagnostic features
include sniffing lower layers such as LL for Classic Bluetooth and Bluetooth
Low Energy (BLE), transmission and reception statistics, test mode, and memory
peek and poke
Mobility through Heterogeneous Networks in a 4G Environment
Serving and Managing users in a heterogeneous environment. 17th WWRF Meeting in Heidelberg, Germany, 15 - 17 November 2006. [Proceeding presented at WG3 - Co-operative and Ad-hoc Networks]The increase will of ubiquitous access of the users to the requested services points towards the integration of heterogeneous networks. In this sense, a user shall be able to access its services through different access technologies, such as WLAN, Wimax, UMTS and DVB technologies, from the same or different network operators, and to seamless move between different networks with active communications. In this paper we propose a mobility architecture able to support this usersâ ubiquitous access and seamless movement, while simultaneously bringing a large flexibility to access network operators
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Open-Source, Open-Architecture SoftwarePlatform for Plug-InElectric Vehicle SmartCharging in California
This interdisciplinary eXtensible Building Operating SystemâVehicles project focuses on controlling plug-in electric vehicle charging at residential and small commercial settings using a novel and flexible open-source, open-architecture charge communication and control platform. The platform provides smart charging functionalities and benefits to the utility, homes, and businesses.This project investigates four important areas of vehicle-grid integration research, integrating technical as well as social and behavioral dimensions: smart charging user needs assessment, advanced load control platform development and testing, smart charging impacts, benefits to the power grid, and smart charging ratepayer benefits
Analysis of RSVP-TE graceful restart
GMPLS is viewed as an attractive intelligent control plane for different network technologies and graceful restart is a key technique in ensuring this control plane is resilient and able to recover adequately from faults. This paper analyses the graceful restart mechanism proposed for a key GMPLS protocol, RSVP-TE. A novel analytical model, which may be readily adapted to study other protocols, is developed. This model allows the efficacy of graceful restart to be evaluated in a number of scenarios. It is found that, unsurprisingly, increasing control message loss and increasing the number of data plane connections both increased the time to complete recovery. It was also discovered that a threshold exists beyond which a relatively small change in the control message loss probability causes a disproportionately large increase in the time to complete recovery. The interesting findings in this work suggest that the performance of graceful restart is worthy of further investigation, with emphasis being placed on exploring procedures to optimise the performance of graceful restart
Smart Microgrids: Overview and Outlook
The idea of changing our energy system from a hierarchical design into a set
of nearly independent microgrids becomes feasible with the availability of
small renewable energy generators. The smart microgrid concept comes with
several challenges in research and engineering targeting load balancing,
pricing, consumer integration and home automation. In this paper we first
provide an overview on these challenges and present approaches that target the
problems identified. While there exist promising algorithms for the particular
field, we see a missing integration which specifically targets smart
microgrids. Therefore, we propose an architecture that integrates the presented
approaches and defines interfaces between the identified components such as
generators, storage, smart and \dq{dumb} devices.Comment: presented at the GI Informatik 2012, Braunschweig Germany, Smart Grid
Worksho
Zika virus infection in pregnant women in Honduras: study protocol
Background: Although there is increasing evidence for a relationship between symptomatic Zika virus (ZIKV) maternal infection, and microcephaly, a firm causal relation has yet to be established by epidemiologic studies. Studies also need to be conducted in recently infected settings. Our objectives are to assess the frequency of ZIKV infection during pregnancy in Honduras and the association of microcephaly with ZIKV infection. Methods/Design: We will perform a prospective study enrolling pregnant women at their first antenatal visit and following them up until delivery. At the time of enrollment, women will be interviewed to collect socio-demographic data, data needed to locate them for potential additional follow-up, and data about ZIKV symptoms during pregnancy. We will also collect maternal blood as soon as possible after enrollment. A probable maternal ZIKV infection will be defined as positive for maternal ZIKV IgM. A confirmed maternal ZIKV infection will be defined as positive for ZIKV IgM confirmed by plaque reduction neutralization test. Microcephaly at birth will be defined as an occipito-frontal circumference <2SD for sex and gestational age. Our objective is to enroll 2000 pregnant women. In a first step, we will follow a case cohort design and only analyze blood samples for cases and a sub-cohort of 200 women randomly selected. Blood samples for the entire population will be analyzed at a later stage if funds are available. Discussion: This protocol was designed to be implemented with minimal resources. It allows a cohort to be built, which could be a foundation for future in-depth and follow-up studies.Fil: Buekens, Pierre. University of Tulane; Estados UnidosFil: Alger, Jackeline. Universidad Nacional AutĂłnoma de Honduras; HondurasFil: Althabe, Fernando. Instituto de Efectividad ClĂnica y Sanitaria; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Bergel, Eduardo. Instituto de Efectividad ClĂnica y Sanitaria; ArgentinaFil: Berrueta, Amanda Mabel. Instituto de Efectividad ClĂnica y Sanitaria; ArgentinaFil: Bustillo, Carolina. Hospital Escuela. Departamento de GinecologĂa y Obstetricia; HondurasFil: Cafferata, Maria Luisa. Hospital de ClĂnicas. Unidad de InvestigaciĂłn ClĂnica y EpidemiolĂłgica Montevideo; UruguayFil: Harville, Emily. University of Tulane; Estados UnidosFil: Rosales, Karla. RegiĂłn Sanitaria Metropolitana Distrito Central de Francisco MorazĂĄn; HondurasFil: Wesson, Dawn M.. University of Tulane; Estados UnidosFil: Zuniga, Concepcion. Hospital Escuela Universitario. Instituto de Enfermedades Infecciosas y ParasitologĂa Antonio Vidal; Hondura
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