Jim Lau - Academia.edu (original) (raw)

Papers by Jim Lau

2018 IEEE Symposium on Computers and Communications (ISCC), 2018

The IEEE 802.11 standard is the most widely-used wireless technology in the industry. In the last... more The IEEE 802.11 standard is the most widely-used wireless technology in the industry. In the last few years, this standard has been subject to multiple revisions to improve the supported Quality of Service (QoS). Among such QoS improvements, we highlight the EDCA and HCCA MAC layer mechanisms, which both work on the top of the DCF (Distributed Coordination Function) mechanism. Currently, DCF is the only commercially-available option in the vast majority of the IEEE 802.11 adapters. Therefore, stations using communication adapters based on any new mechanism must be able to provide QoS guarantees in the presence of stations using state-of-the-art DCF adapters. In this paper, we perform an experimental assessment of the coexistence of EDCA and DCF mechanism in a real-time (RT) communication scenario. More specifically, we assess the ability of the EDCA mechanism to handle RT traffic in overlapping basic service set (OBSS) scenarios, where RT stations share the same frequency channel and coverage area with alien DCF stations. The main purpose of this paper is to understand the limitations of the EDCA mechanism when supporting RT traffic in open communication scenarios. We show that when the environment is shared with non-RT alien devices operating under the traditional DCF mechanism, the EDCA mechanism is not able to adequately support RT traffic.

Journal of Communications and Networks, 2019

In this paper, the RT-WiFi architecture is proposed to handle real-time (RT) communication in inf... more In this paper, the RT-WiFi architecture is proposed to handle real-time (RT) communication in infrastructured IEEE 802.11 networks operating in high density industrial environments. This architecture is composed of a time division multiple access (TDMA)-based coordination layer that schedules the medium access of RT traffic flows, and an underlying traffic separation mechanism that is able do handle the coexistence of RT and non-RT traffic sources in the same communication environment. The simulation assessment considers an overlapping basic service set (OBSS), where a set of RT and non-RT stations share the same frequency band. The performance assessment compares the behaviour of the RT-WiFi architecture vs. the behaviour of standard distributed coordination function (DCF), point coordination function (PCF), enhanced distributed channel access (EDCA), and hybrid coordination function (HCF) controlled channel access (HCCA) medium access control mechanisms. A realistic error-prone model has been used to measure the impact of message losses in the RT-WiFi architecture. It is shown that the proposed RT-WiFi architecture offers a significantly enhanced behaviour when compared with the use of IEEE 802.11 standard mechanisms, in what concerns average deadline misses and average access delays. Moreover, it also offers an almost constant access delay, which is a relevant characteristic when supporting RT applications.

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de ... more Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia Elétrica.A tecnologia de Serviços Web provê uma abordagem para o desenvolvimento de aplicações distribuídas utilizando interfaces simples e bem definidas. Devido à flexibilidade desta arquitetura, é possível a composição de processos de negócios, integrando serviços em sistema de larga escala. Apesar de toda a flexibilidade provida pela tecnologia de Serviço Web para construção de soluções distribuídas, aspectos ligados a confiabilidade e a tolerância a faltas, tão necessário para aplicações em ambiente complexo, não foram objetos de padronização. O presente trabalho propõe uma abordagem própria para arquiteturas orientadas a serviço que busca atender os requisitos de confiabilidade. Esta abordagem está centrada no conceito de statefull para Serviços Web tolerantes a faltas. A abordagem é implementada no contexto de uma infra-estrutura de serviço chamada de FTWS-Orch, que combina a utilização de mecanismos de transação e de técnicas de replicação ativa e passiva, fazendo o uso para tanto, da orquestração de Serviços Web. Este modelo foi centrado sob a premissa de ocorrência de faltas de parada (crash)

2012 IEEE 19th International Conference on Web Services, 2012

ABSTRACT The web services technology provides an approach for developing distributed applications... more ABSTRACT The web services technology provides an approach for developing distributed applications by using simple and well defined interfaces. Due to the flexibility of this architecture, it is possible to compose business processes integrating services from different domains. This paper presents an approach, which uses the specification of services orchestration, in order to create a fault tolerant model combining active and passive replication technique. This model supports fault of crash and value. The characteristics and the results obtained by implementing this model are described along this paper Resumo. A tecnologia de serviços web provê uma abordagem para o desenvolvimento de aplicações distribuídas utilizando interfaces simples e bem definidas. Devido à flexibilidade desta arquitetura, é possível a composição de processos de negócios integrando serviços de domínios distintos. Este artigo apresenta uma proposta de utilização das especificações para orquestração de serviços, na implementação de uma arquitetura tolerante a faltas utilizando uma combinação de técnica de replicação ativa e passiva. Este modelo suporta falta de crash e valor. As características e os resultados obtidos com a definição desta arquitetura são descritos no decorrer deste artigo.

Anais do XXII Simpósio Brasileiro de Segurança da Informação e de Sistemas Computacionais (SBSeg 2022)

Existe uma demanda crescente de novos dispositivos para a área médica, considerando a Internet da... more Existe uma demanda crescente de novos dispositivos para a área médica, considerando a Internet das Coisas. Este artigo tem como objetivo avaliar de forma experimental uma camada de segurança para um vestível cardíaco projetado para realizar exames de eletrocardiograma sem fio e remoto. Para torná-lo menos suscetível aos principais ataques conhecidos, como homem-do-meio e espionagem, métodos de criptografia foram testados para analisar sua viabilidade. Três algoritmos de criptografia (AES-256 CBC, SPECK e CLEFIA) foram implementados e comparados em um ambiente de comunicação seguro e autenticado, a fim de analisar seu desempenho com relação à latência da rede e testes de carga do dispositivo. Foram feitas várias amostras de dados de medição e posteriormente, analisado graficamente e comparado. O AES-256 CBC apresentou melhores resultados, sendo o algoritmo mais indicado para uma camada de segurança do vestível cardíaco.

Resumo. Diversas pesquisas para desenvolvimento de soluções práticas de suporte a aplicações dist... more Resumo. Diversas pesquisas para desenvolvimento de soluções práticas de suporte a aplicações distribuídas tolerantes a faltas bizantinas têm sido realizadas nos últimos anos. Estas soluções visam tornar as aplicações resistentes inclusive a ataques maliciosos bem sucedidos contra o sistema, tornando assim os serviços tolerantes a intrusões. Recentemente, alguns destes trabalhos têm considerado o uso de virtualização para a construção de um ambiente de computação confiável.

Much research aiming to design practical algorithms to support Byzantine Fault-Tolerant distribut... more Much research aiming to design practical algorithms to support Byzantine Fault-Tolerant distributed applications has been made in recent years. These solutions are designed to make the applications resistant to successful attacks against the system, thereby making services tolerant to intrusions. Recently, some of these studies have considered the use of virtual machines for building a trusted computing environment. This paper presents SMIT (Shared Memory based Intrusion Tolerance), an architecture for Intrusion Tolerance using virtual machines that benefits from a shared memory to simplify the consensus protocol.

Much research aiming to design practical algorithms to support Byzantine Fault-Tolerant distribut... more Much research aiming to design practical algorithms to support Byzantine Fault-Tolerant distributed applications has been made in recent years. These solutions are designed to make the applications resistant to successful attacks against the system, thereby making services tolerant to intrusions. Recently, some of these studies have considered the use of virtual machines for building an environment of trusted computing. These proposals aim to implement service and operating system diversity at virtual machine level. This paper presents VMBFT, an architecture for Byzantine Fault-Tolerance using virtual machines.

The Web services technology provides an approach for developing distributed applications by using... more The Web services technology provides an approach for developing distributed applications by using simple and well defined interfaces. Due to the flexibility of this architecture, it is possible to compose business processes integrating services from different domains. This paper presents an approach, which uses the specification of services orchestration, in order to create a fault tolerant model combining active and passive replication technique. This model support fault of crash. The characteristics and the results obtained by implementing this model are described along this paper.

Effluent discharges from pulp mill, sewage, or pesticide run-off are released into aquatic enviro... more Effluent discharges from pulp mill, sewage, or pesticide run-off are released into aquatic environments as complex mixtures. This study uses two types of discharge compounds (an insecticide and a pulp mill condensate) to illustrate the LC/Q-TOF sensitivity, linear range, quantitative, and qualitative analysis functionalities.

Perfluoroalkyl substances (PFASs) have been widely used in a variety of products due to their che... more Perfluoroalkyl substances (PFASs) have been widely used in a variety of products due to their chemical inertness, resistance to heat, and ability to repel water and oils. PFASs exhibit a high propensity for persistence and bioaccumulation in wildlife, which is causing concern. Due to different manufacturing and degradation processes, different chain lengths and functional groups of PFAS exist in the environment. An LC/Q-TOF is best suited to screen, identify, and quantify many perfluoroalkyl compounds in different matrices.

2018 IEEE Symposium on Computers and Communications (ISCC), 2018

The IEEE 802.11 standard is the most widely-used wireless technology in the industry. In the last... more The IEEE 802.11 standard is the most widely-used wireless technology in the industry. In the last few years, this standard has been subject to multiple revisions to improve the supported Quality of Service (QoS). Among such QoS improvements, we highlight the EDCA and HCCA MAC layer mechanisms, which both work on the top of the DCF (Distributed Coordination Function) mechanism. Currently, DCF is the only commercially-available option in the vast majority of the IEEE 802.11 adapters. Therefore, stations using communication adapters based on any new mechanism must be able to provide QoS guarantees in the presence of stations using state-of-the-art DCF adapters. In this paper, we perform an experimental assessment of the coexistence of EDCA and DCF mechanism in a real-time (RT) communication scenario. More specifically, we assess the ability of the EDCA mechanism to handle RT traffic in overlapping basic service set (OBSS) scenarios, where RT stations share the same frequency channel and coverage area with alien DCF stations. The main purpose of this paper is to understand the limitations of the EDCA mechanism when supporting RT traffic in open communication scenarios. We show that when the environment is shared with non-RT alien devices operating under the traditional DCF mechanism, the EDCA mechanism is not able to adequately support RT traffic.

Journal of Communications and Networks, 2019

In this paper, the RT-WiFi architecture is proposed to handle real-time (RT) communication in inf... more In this paper, the RT-WiFi architecture is proposed to handle real-time (RT) communication in infrastructured IEEE 802.11 networks operating in high density industrial environments. This architecture is composed of a time division multiple access (TDMA)-based coordination layer that schedules the medium access of RT traffic flows, and an underlying traffic separation mechanism that is able do handle the coexistence of RT and non-RT traffic sources in the same communication environment. The simulation assessment considers an overlapping basic service set (OBSS), where a set of RT and non-RT stations share the same frequency band. The performance assessment compares the behaviour of the RT-WiFi architecture vs. the behaviour of standard distributed coordination function (DCF), point coordination function (PCF), enhanced distributed channel access (EDCA), and hybrid coordination function (HCF) controlled channel access (HCCA) medium access control mechanisms. A realistic error-prone model has been used to measure the impact of message losses in the RT-WiFi architecture. It is shown that the proposed RT-WiFi architecture offers a significantly enhanced behaviour when compared with the use of IEEE 802.11 standard mechanisms, in what concerns average deadline misses and average access delays. Moreover, it also offers an almost constant access delay, which is a relevant characteristic when supporting RT applications.

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de ... more Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia Elétrica.A tecnologia de Serviços Web provê uma abordagem para o desenvolvimento de aplicações distribuídas utilizando interfaces simples e bem definidas. Devido à flexibilidade desta arquitetura, é possível a composição de processos de negócios, integrando serviços em sistema de larga escala. Apesar de toda a flexibilidade provida pela tecnologia de Serviço Web para construção de soluções distribuídas, aspectos ligados a confiabilidade e a tolerância a faltas, tão necessário para aplicações em ambiente complexo, não foram objetos de padronização. O presente trabalho propõe uma abordagem própria para arquiteturas orientadas a serviço que busca atender os requisitos de confiabilidade. Esta abordagem está centrada no conceito de statefull para Serviços Web tolerantes a faltas. A abordagem é implementada no contexto de uma infra-estrutura de serviço chamada de FTWS-Orch, que combina a utilização de mecanismos de transação e de técnicas de replicação ativa e passiva, fazendo o uso para tanto, da orquestração de Serviços Web. Este modelo foi centrado sob a premissa de ocorrência de faltas de parada (crash)

2012 IEEE 19th International Conference on Web Services, 2012

ABSTRACT The web services technology provides an approach for developing distributed applications... more ABSTRACT The web services technology provides an approach for developing distributed applications by using simple and well defined interfaces. Due to the flexibility of this architecture, it is possible to compose business processes integrating services from different domains. This paper presents an approach, which uses the specification of services orchestration, in order to create a fault tolerant model combining active and passive replication technique. This model supports fault of crash and value. The characteristics and the results obtained by implementing this model are described along this paper Resumo. A tecnologia de serviços web provê uma abordagem para o desenvolvimento de aplicações distribuídas utilizando interfaces simples e bem definidas. Devido à flexibilidade desta arquitetura, é possível a composição de processos de negócios integrando serviços de domínios distintos. Este artigo apresenta uma proposta de utilização das especificações para orquestração de serviços, na implementação de uma arquitetura tolerante a faltas utilizando uma combinação de técnica de replicação ativa e passiva. Este modelo suporta falta de crash e valor. As características e os resultados obtidos com a definição desta arquitetura são descritos no decorrer deste artigo.

Anais do XXII Simpósio Brasileiro de Segurança da Informação e de Sistemas Computacionais (SBSeg 2022)

Existe uma demanda crescente de novos dispositivos para a área médica, considerando a Internet da... more Existe uma demanda crescente de novos dispositivos para a área médica, considerando a Internet das Coisas. Este artigo tem como objetivo avaliar de forma experimental uma camada de segurança para um vestível cardíaco projetado para realizar exames de eletrocardiograma sem fio e remoto. Para torná-lo menos suscetível aos principais ataques conhecidos, como homem-do-meio e espionagem, métodos de criptografia foram testados para analisar sua viabilidade. Três algoritmos de criptografia (AES-256 CBC, SPECK e CLEFIA) foram implementados e comparados em um ambiente de comunicação seguro e autenticado, a fim de analisar seu desempenho com relação à latência da rede e testes de carga do dispositivo. Foram feitas várias amostras de dados de medição e posteriormente, analisado graficamente e comparado. O AES-256 CBC apresentou melhores resultados, sendo o algoritmo mais indicado para uma camada de segurança do vestível cardíaco.

Resumo. Diversas pesquisas para desenvolvimento de soluções práticas de suporte a aplicações dist... more Resumo. Diversas pesquisas para desenvolvimento de soluções práticas de suporte a aplicações distribuídas tolerantes a faltas bizantinas têm sido realizadas nos últimos anos. Estas soluções visam tornar as aplicações resistentes inclusive a ataques maliciosos bem sucedidos contra o sistema, tornando assim os serviços tolerantes a intrusões. Recentemente, alguns destes trabalhos têm considerado o uso de virtualização para a construção de um ambiente de computação confiável.

Much research aiming to design practical algorithms to support Byzantine Fault-Tolerant distribut... more Much research aiming to design practical algorithms to support Byzantine Fault-Tolerant distributed applications has been made in recent years. These solutions are designed to make the applications resistant to successful attacks against the system, thereby making services tolerant to intrusions. Recently, some of these studies have considered the use of virtual machines for building a trusted computing environment. This paper presents SMIT (Shared Memory based Intrusion Tolerance), an architecture for Intrusion Tolerance using virtual machines that benefits from a shared memory to simplify the consensus protocol.

Much research aiming to design practical algorithms to support Byzantine Fault-Tolerant distribut... more Much research aiming to design practical algorithms to support Byzantine Fault-Tolerant distributed applications has been made in recent years. These solutions are designed to make the applications resistant to successful attacks against the system, thereby making services tolerant to intrusions. Recently, some of these studies have considered the use of virtual machines for building an environment of trusted computing. These proposals aim to implement service and operating system diversity at virtual machine level. This paper presents VMBFT, an architecture for Byzantine Fault-Tolerance using virtual machines.

The Web services technology provides an approach for developing distributed applications by using... more The Web services technology provides an approach for developing distributed applications by using simple and well defined interfaces. Due to the flexibility of this architecture, it is possible to compose business processes integrating services from different domains. This paper presents an approach, which uses the specification of services orchestration, in order to create a fault tolerant model combining active and passive replication technique. This model support fault of crash. The characteristics and the results obtained by implementing this model are described along this paper.

Effluent discharges from pulp mill, sewage, or pesticide run-off are released into aquatic enviro... more Effluent discharges from pulp mill, sewage, or pesticide run-off are released into aquatic environments as complex mixtures. This study uses two types of discharge compounds (an insecticide and a pulp mill condensate) to illustrate the LC/Q-TOF sensitivity, linear range, quantitative, and qualitative analysis functionalities.

Perfluoroalkyl substances (PFASs) have been widely used in a variety of products due to their che... more Perfluoroalkyl substances (PFASs) have been widely used in a variety of products due to their chemical inertness, resistance to heat, and ability to repel water and oils. PFASs exhibit a high propensity for persistence and bioaccumulation in wildlife, which is causing concern. Due to different manufacturing and degradation processes, different chain lengths and functional groups of PFAS exist in the environment. An LC/Q-TOF is best suited to screen, identify, and quantify many perfluoroalkyl compounds in different matrices.