Data Communications and Networking

The rapid evolution toward 6G and beyond has intensified interest in Programmable Wireless Environments (PWEs) enabled by Smart Surfaces and Intelligent Reflecting Surfaces (IRS). These engineered metasurfaces, composed of sub-wavelength reconfigurable unit cells, allow for precise control of electromagnetic wave properties such as phase, amplitude, and polarization. Unlike traditional relay-based systems, IRSs passively manipulate incident waves to improve coverage, reduce interference, and enhance channel capacity with minimal power consumption. This paper explores IRS design principles, control mechanisms, and deployment strategies for both indoor and outdoor scenarios. Special attention is given to programmable meta-atoms, integration with AI/ML for adaptive beam control, and challenges such as scalability, channel estimation, and energy efficiency. Simulation and experimental studies demonstrate that IRS-assisted networks can significantly improve spectral efficiency, reduce path loss, and enhance reliability in dense urban and complex indoor environments. The paper concludes with future research directions, including hybrid IRS-MIMO architectures, energy harvesting IRSs, and integration into Space-Air-Ground-Sea (SAGS) networks.

Sensors are being extensively deployed and are expected to expand at significant rates in the coming years. They typically generate a large volume of data on the internet of things (IoT) application areas like smart cities, intelligent traffic systems, smart grid, and e-health. Cloud, edge and fog computing are potential and competitive strategies for collecting, processing, and distributing IoT data. However, cloud, edge, and fog-based solutions need to tackle the distribution of a high volume of IoT data efficiently through constrained and limited resource network infrastructures. This paper addresses the issue of conveying a massive volume of IoT data through a network with limited communications resources (bandwidth) using a cognitive communications resource allocation based on Reinforcement Learning (RL) with SARSA algorithm. The proposed network infrastructure (PSIoTRL) uses a Publish/ Subscribe architecture to access massive and highly distributed IoT data. It is demonstrated...

This paper presents a comprehensive literature review on applications and design aspects of the intelligent reflecting surface (IRS) in the future wireless networks. Conventionally, the network optimization has been limited to transmission control at two endpoints, i.e., end users and network controller. The fading wireless channel is uncontrollable and becomes one of the main limiting factors for performance improvement. The IRS is composed of a large array of scattering elements, which can be individually configured to generate additional phase shifts to the signal reflections. Hence, it can actively control the signal propagation properties in favor of signal reception, and thus realize the notion of a smart radio environment. As such, the IRS’s phase control combined with the conventional transmission control can potentially bring performance gain compared to the conventional wireless networks without using the IRS. In this survey, we first introduce basic concepts of the IRS an...

Network Intrusion Detection (ID) attempts to detect diverse security attacks using a security system to monitor, analyze, detect, and respond to threats. In Software Defined Networking (SDN), ID that typically occurs at the controller is influenced by application policies and is advantageous over generic networking due to the network and flow awareness of the controller and the threat response capability of the controller itself. A blockchain system embodies a succession of attached blocks that implicitly maintain the purity, preserve the indisputability, and preserve the quasi-anonymity of its transactions/activities because of consensus protocols and cryptographic algorithms. Being the front-line reviewers for BCcentered ID in SDN, we group blockchain roles in ID in three ways and elaborately examine those pertaining to ID techniques and ID approaches, blockchain components, attack detection, network components, and so forth. We stacked a preliminary sample of 97 paper sources by sifting through the articles for selection guidelines inquired from virtual libraries, applying an elaborate and overtime procedure. Centered upon this examination, blockchain-centered ID in SDN involves collaborative ID by engaging smart contracts while storing data required for threat detection in blockchain, off-chain ID while applying blockchain for trust management, and applying blockchain for authentication and secure data storage for off-chain ID. Elaborate examination divulges that from blockchain-centered SDN ID proposals, 48.9% apply blockchaincentered secure storage for off-chain ID, 91.2% engage systematic blockchain architecture, 8.9% apply PoAuthority consensus, 100% online, 75.5% active response, 71.1% fully distributed, and 57.8% apply hybrid host and networkcentered ID, with DDoS being the most dominant (17.8%) specific attack category. Finally, we explore the potentials and hardships of the schema of blockchain-centered ID in SDN and then supply insights to overtake them.

Load Balancing (LB) in networking attempts to minimize the under-utilization and over-utilization of network resources by distributing the network flows evenly in the communication network. Blockchain includes a string of joined blocks that are built into the preservation of the non-tampering nature and safeguarding the verifiability. According to our felt experience, we are the initiators to review on blockchain-driven LB, where we organize the blockchain-driven LB concept under 7 categories and interpret thoroughly their performance in relation to LB techniques, BC-driven variables, LB approach, network variables, and similar things. We accumulated an early sample of 76 paper citations by handpicking articles for eligibility requirements scrutinized from web repositories, deploying a thorough and continuous method. Relying on this assessment, blockchain has been deployed in network LB for protecting data fidelity, trustworthiness, confidentiality of data transfers, deploying blockchain consensus for LB, deploying smart contracts for LB, deploying with secure resource trading, access control, and as a coordinator in the system of LB. Moreover, LB involves balancing loads in the blockchain transactions themselves. Thorough interpretation depicts that from blockchaindriven LB schemes, 37.5% deploy blockchain transaction LB, 90% deploy conventional blockchain architecture, 30% deploy generic consensus, 97.5% deploy decentralized LB, 97.5% deploy dynamic LB, 52.5% deploy deterministic LB, and the majority target generic networks. Finally, we go over the potential and predicaments of the notion of blockchain-driven LB and then provision ideas to defeat them.

A detailed report of the spectrum occupancy measurement drive conducted outdoors in three rural villages of Asong in Mkpat Enin, Ikot Akpabio in Etinan, and Afaha Offioing in Nsit Ibom Local Government Areas of Akwa Ibom state in Nigeria on the UHF and VHF broadcast frequency bands is here presented. The spectrum usage on a highly conservative noise floor, was high in the VHF band, thereby not having enough free bandwidth for secondary spectrum access while the UHF band percentage utilization for the three villages were found to be at 33%, 41% and 55% with available free cumulative bandwidths of 264MHz, 232MHz, and 176MHz respectively. From the findings, Nigeria can comfortably accommodate a lightly licensed spectrum band in the UHF band to enhancer rural broadband services.

Wireless Body Area Networks (WBANs) are critical components of emerging smart healthcare solutions. Due to the intrinsic nature of wireless communication and the potentially sensitive medical data they carry, such networks are often very vulnerable to many types of security threats. As a result, the security of WBANs becomes a prime concern when they are considered for use in healthcare or medical applications. This text enumerates common security threats that a typical WBAN should prepare for. It also provides a set of enhancement mechanisms and techniques that could be implemented to augment the security of WBANs. Furthermore, a vital precautionary activity that should be taken in the initial steps towards developing a secure WBAN system-threat modeling-is also described. This text presents two elaborated example cases for the threat modeling technique for WBANs: patrolling and insulin injection WBANs. The cases demonstrate that threats in WBANs are further sources of vulnerabilities, beyond the definition of threats from common knowledge, that should be evaluated and addressed before deployment. Results show that there are plenty of possible problems that threaten the security and privacy of WBAN systems, which should be taken into strong consideration. It is believed that the proposed threat modeling methodology here will significantly contribute to secure designs of WBANs and can also potentially be generalized to other embedded systems as well.

In this paper the performance of one of the most widely deployed Wireless Local Area Networks (WLANs) based on IEEE 802. 11a standard has been analyzed using different modulation technique and convolution coding rates. The IEEE 802. 11a standard uses Orthogonal Frequency Division Multiplexing (OFDM) technique. In this analysis the channel estimation is pilot symbol based. A particular method proposed in literature, known as the Least Square Method (LS), along with its enhancement using Discrete Fourier transform (DFT) based estimator is investigated in this work. Three categories of channel profiles are considered for simulation, namely highly frequency selective, moderately frequency selective and frequency flat channels. The performances using these methods are compared by measuring raw bit-errorrate (BER) & mean square error (MSE), using 16 QAM modulation technique with different code rate in three different fading channel profile.

Resumo-Estima-se que 80% das redes locais actuais sejam baseadas em tecnologia Ethernet. Apesar de algum criticismo em redor deste tipo de rede, as previsões não apontam para uma diminuição da quota de mercado. O aumento do débito introduzido com o Fast Ethernet e, mais recentemente, com o Gigabit Ethernet, torna esta tecnologia novamente competitiva. O objectivo deste artigo é a apresentação das normas mais recentes nesta área, bem como a discussão de alguns cenários futuros de aplicação. Abstract-Nowadays, around 80% of local area networks are Ethernet based. However, aside from all the criticism over Ethernet technology, the market share does not tend to decrease. The growth of transmission speed, introduced with Fast Ethernet and, more recently, with Gigabit Ethernet, keeps the technology up to date, in despite of some limitations introduced by the compatibility with previous standards.

Current traditional IP networks start to be complex as the demands of the users is ever-growing. Software Defined Network (SDN) is a new paradigm to ease the management of the network and make the network programmable by decoupling the control plane and forwarding plane (such as switch and router). A centralized controller is used to manage the control plane, and it interacts with forwarding plane using a standardized OpenFlow protocol. However, many controllers are used recently such as POX, Ryu, ONOS, and OpenDaylight. The important question is which is the best controller to use in our network and fits our network's goals? To answer this question, a decision making method is proposed in this paper. First, four SDN controllers are selected, and five criteria are analyzed to collect these controllers' properties. Then a Multi-Criteria Decision Making method named TOPSIS is used to rank the controllers and choose the best one. By applying this method, a comparative study is done to evaluate the four controllers in an environment of LAN topology, and "Ryu" controller is selected as the best one based on our criteria.

À Deus por me dar sabedoria, saúde e forças nos momentos difíceis. À minha amada esposa Fernanda por suportar a saudade e todas as demais dificuldades vividas no meses em que ficamos distantes. À minha linda filha Rebeca por alegrar meus dias a cada sorriso, e me motivar a buscar crescimento em prol de sua felicidade. Aos meus pais Tibério e Kátia, meu irmão Renan, e minha avó Suzana que tanto investiram na minha formação, e por estarem sempre na torcida pelo meu sucesso, devo o que sou a vocês. Aos colegas da Fundação CERTI, em especial ao Bruno Herrera e Andrei Biscaro pelo suporte, flexibilidade, profissionalismo, e demais contribuições importantíssimos para o meu crescimento técnico e profissional no tempo em que permaneci em Florianópolis. Aos colegas do laboratório de TV Digital do CTPIM. Ao orientador Eduardo Bezerra pela orientação, disponibilidade e paciência. Ao co-orientador e amigo Eddie Filho pela motivação, conselhos, e dedicação fundamentais para a realização deste trabalho e para minha formação acadêmica. Aos colegas do GSE, em particular Frederico Ferlini, Paulo Villa, e Felipe Silva pelo suporte técnico durante as implementações. À todos aqueles que de alguma maneira contribuíram para que eu obtivesse este título. "Você não sabe o quanto eu caminhei pra chegar até aqui. Percorri milhas e milhas antes de dormir, eu nem cochilei..." Toni Garrido RESUMO O Fluxo de Transporte (Transport Stream-TS) MPEG-2 é um formato amplamente utilizado em sistemas de TV Digital para a transmissão de áudio, vídeo e informações relacionadas a programa. Entre outras informações, um fluxo de transporte carrega uma referência de tempo, conhecida como Referência de Relógio de Programa (Program Clock Reference-PCR), a qual é um retrato do relógio de 27 MHz do sistema. Esta informação permite a recuperação do relógio nos receptores, o qual garante a correta apresentação do conteúdo e até mesmo controla interfaces de saída. Porém, se o tempo de chegada dos pacotes de transporte variar durante a transmissão ou o processamento, tal cenário pode levar a erros no relógio do sistema, o que é conhecido como jitter. Os métodos tradicionais para a correção da informação do relógio de programa normalmente são baseadas em contadores/acumuladores de 27 MHz com ponto flutuante, porém, não mitigam o jitter de PCR completamente. Métodos mais recentes usam contador/acumulador controlado por semáforo, e até mesmo propõem um esquema de adaptação de taxa integrada à correção da referência de relógio, a qual resulta em baixos níveis de jitter na saída. Além disto, não há estudos a respeito da implementação dos métodos controlados por semáforo em processadores de fluxo de transporte. Com isto, o presente trabalho propõe uma metodologia para implementação em FPGA, utilizando linguagem de descrição de hardware. Os resultados obtidos validam o uso dos métodos controlados por semáforo e mostram que a estrutura proposta é efetiva, com o benefício de eliminar efeitos de metaestabilidade. Palavras-chave: MPEG-2 TS, Correção de PCR, FPGA.

Esta monografia está organizada em cinco capítulos. No capítulo 1 é feita uma rápida introdução ao tema e são apresentados objetivo e estrutura do trabalho. No capítulo 2 é apresentada uma visão geral sobre o padrão 802.11 focando-se nos processos de autenticação e de associação de estações móveis. No capítulo 3 são abordadas noções de python, scapy, wireshark e linux que são as ferramentas utilizadas para realizar o objetivo do trabalho. No capitulo 4 são utilizadas as ferramentas do capítulo 3 para forjar quadros de gerenciamento e injetá-los na rede sem fio. No final desse capítulo os scripts são criados e executados. No capitulo 5 analisa-se o comportamento das estações e de algumas marcas de access points quando submetidos aos ataques de negação de serviço descritos neste trabalho. No capítulo 6, são apresentadas as conclusões onde são expostos os ganhos ao conhecimento proporcionados por esta monografia e as considerações finais onde são feitas propostas para trabalhos futuros. Nome do autor 2 Capítulo 3-Conclusões e Trabalhos Futuros Capítulo 2 Serviços de Desautenticação e de Associação em uma rede 802.11 2.1 Arquitetura de uma rede 802.11 Uma rede 802.11 pode ser basicamente composta por um ponto de acesso ou access point (AP) e por estações. Quando não há access point, diz-se que a arquitetura da rede sem fio é do tipo ad hoc ou IBSS (independent BSS). Havendo um AP, tem-se uma rede infraestruturada. Nestre trabalho serão consideradas

In 2016, WhatsApp implemented the end-to-end encryption system Signal Protocol to protect all data transmitted in order to prevent any unauthorized third-party access to that information. However, although the cryptographic system is open source, its implementation has been little published by the company. The purpose of this work is to study the implementation of this system to ensure that WhatsApp uses this encryption system and is unable to access the content of the messages from its users. For this, a code injection was used on an Android device to capture messages and keys, and forward it to a thirdparty system based on Signal Protocol. The results show that the company uses the system properly, without access to the private keys of users and messages content. Resumo. Em 2016, WhatsApp implementou o sistema de criptografia fim-a-fim Signal Protocol para proteger todos os dados transmitidos, de forma a previnir que acessos terceiros não-autorizados possam obter informações. Entr...

Fiber optic and copper cables are the two famous cables used in communication system. Selecting the appropriate cable for effective communication project can be challenging. Nevertheless, knowing the distinct properties of fiber optic and copper can be the solution. This paper provides a comparative analysis of the differences between fiber optic and copper in communication system. The analysis encompasses the security, bandwidth and distance, cost, flexibility and size, immunity and safety etc. Each cable, has its place in the design of any communication system.

A WBAN is predicted as a valuable technology being used in many applications, especially in medical application for monitoring and detection of possible problems of patients. Some of the issues are addressed in WBANs, in which the critical issues need to be solved are energy saving and security along with inter-WBANs interference. To evade the inter-WBANs interference along with the control the transmission power on WBAN system, this paper presents a cooperative based power control game algorithm which is utilized with the social interaction information model. In order to manage the WBAN with the security measures to transmit the patient data throughout the system an Elliptic Curve Cryptography (ECC) algorithm is used for authentication before initiating the transmission. The performance of the proposed approach is evaluated along with the increased number of nodes while the occurrence of an interference problem is also rigorous. The proposed approach provides the better results whe...

In this paper highlights a four-level information-driven framework for image mining systems, various methods available from literature, historical background, related work, algorithms and techniques that are frequently used in image mining, namely object recognition, image retrieval, image indexing, image classification and clustering, association rule mining and neural network.

The transmission of real-time multimedia streams requires service guarantees, such as limited packet loss, minimum bandwidth and limited delay and jitter, in order to deliver a good quality of experience (QoE) for viewers. The spatial and temporal redundancy of videos is explored by coding algorithms, reducing the amount of information necessary to represent the images. As a consequence, multimedia traffic commonly presents variable bit rate behavior and self-similar characteristics. Although the reduction in bandwidth requirements is highly desirable, the burstiness of traffic leads to problems in network design and performance prediction. Particularly in the case of video streaming, the self similar behavior tends to increase the average packet delay and jitter, and increase the probability of packet loss. Even a low level of packet loss could severely affect the viewer QoE. In this paper, we propose the use of traffic shaping to reduce the burstiness of video traffic. We choose to use the token bucket algorithm due its simplicity and its wide utilization in computer networks. The main contribution of the paper is the method to configure the parameters of token bucket using the video characteristics. The efficiency of proposed method is demonstrated through computer simulations and the results indicate that the use of proposed method effectively improves the QoE.

Delivering quality of service in packetized mobile cellular systems is costly, yet critical. Recently, cross-layer connection admission control policies [1] [2] have been shown to realize network performance objectives for multimedia transmission that include constraints on delay and blocking probability. Current third generation (3G) systems such as high speed uplink packet access (HSUPA) employ a threshold-based admission control (AC) policy to reserve capacity to increase quality of service (QoS). In threshold-based AC, a user request is admitted if the load reported is below a threshold. Although a threshold-based AC policy is simple to implement and may be improved upon to take into account resource allocation information [3], it unfortunately cannot meet upper layer QoS requirements, such as required in the data-link and network layers [4]. In this chapter, AC policies are investigated for packetized code division multiple access (CDMA) systems that can both maximize overall system throughput and simultaneously guarantee quality of service (QoS) requirements in both physical and upper layers. To further improve user capacity, multiple antennas are employed at the base station, and a truncated automatic repeat request (ARQ) scheme is employed in the data link layer of the system under investigation. Truncated ARQ is an error-control protocol which retransmits an erroneous packet until either it is correctly received or until a maximum number of retransmissions is reached. The design of optimal connection admission control policies for a packetized CDMA system that incorporates an advanced multi-beamformer basestation at the physical layer and ARQ at the data link layer has, to the authors' knowledge, not been addressed previously. For example, the call level admission control policies for CDMA systems in [4] [5] [6] only focus on circuit-switched networks, in which radio resources allocated to a user are unchanged throughout the call connection, leading to inefficient utilization of system resources, especially for bursty multimedia traffic. In [7] [8], the CAC problem is extended to packetswitched CDMA systems. Unfortunately, the CAC modelling in [7] [8] has been limited to optimizing power control and admission control policies to specific systems, in which physical layer performance, characterized in terms of signal-to-interference (SIR) in each service class, is static. With multiple antennas systems, which are widely employed in current 3G CDMA systems [9]-[14], the physical layer performance depends not only on system state, but also on factors such as spatial angle of arrival (AoA). Therefore, the existing CAC framework in [7] [8] cannot adequately incorporate multiple antenna base

It is anticipated that communication between two or more computing devices (Inter-Device) would piece together an important part of any forthcoming wireless link by way of its assurances in providing extremely low latency on behalf of messaging amongst operators. Such innovative approach would possibly function in a spectrum that is either certified or prohibited. Inter Device linkage therefore emerges as a unique addition to the old-fashioned cell phone messaging architype, whose underlying merits are nonetheless, supplemented by many practical and commercial concerns that are essential to a prompt resolution, in advance of assimilating it into a cellular connection. The main aim of this paper is to ascertain some core features of inter device links together with its procedural set-ups, design, practical features and the extent of any other active study. Research papers, Journals, Internet Sites, and books were used to organise the subject's relevant content. The analysis conducted by this study indicates that momentary overview of (ID) communication has been offered above in relations to its functionalities, design and the key technical experiments to its execution.

Following the standardization and deployment of fifth-generation (5G) network, researchers have shifted their focus to beyond 5G communication. Existing technologies have brought forth a plethora of applications that could not have been imagined in the past years. Beyond 5G will enable us to rethink the capability, it will offer in various sectors including agriculture, search and rescue and more specifically in the delivery of health care services. Unobtrusive and non-invasive measurements using radio frequency (RF) sensing, monitoring and control of wearable medical devices are the areas that would potentially benefit from beyond 5G. Applications such as RF sensing, device charging and remote patient monitoring will be a key challenge using millimetre (mmWave) communication. The mmWaves experience multi-path induced fading, where the rate of attenuation is larger as compared to the microwaves. Eventually, mmWave communication systems would require range extenders and guided surfaces. A proposed solution is the use of intelligent reflective surfaces, which will have the ability to manipulate electromagnetic (EM) signals. These intelligent surfaces mounted and/or coated on walls aka-'Intelligent Walls' are planar and active surfaces, which will be a key element in beyond 5G and 6G communication. These intelligent walls equipped with machine learning algorithm and computation power would have the ability to manipulate EM waves and act as gateways in the heterogeneous network environment. The article presents the application and vision of intelligent walls for next-generation healthcare in the era of beyond 5G.

Resumo. As redes de computadores atuais, em geral, possuem alta capacidade de transmissão. Apesar disso, o controle do compartilhamento de largura de banda aindaé uma questão relevante, poisé preciso observar que, por maior que ela seja, a largura de banda sempre será finita. Assim, a necessidade do gerenciamento de largura de banda surge principalmente pelo fato de se tratar de um recurso limitado que precisa ser suficiente para comportar as infinitas possibilidades de utilização das redes de computadores. Considerando essa necessidade, como projeto de dissertação, propõe-se um sistema de gerenciamento adaptativo da largura de banda do enlace de saída do gateway de uma rede local IPv4 baseado em predição de tráfego utilizando transformadas wavelets. Especificamente, o objetivoé desenvolver e implementar um sistema de gerenciamento que permita que a largura de banda do enlace de saída seja compartilhada de forma justa entre as interface de entrada do gateway da rede. Palavras-Chave. largura de banda; wavelets; predição de tráfego; SNMP.

The MetroBel network was a pioneer network in the national context, launched in 2007, connecting several teaching and research institutions in the metropolitan region of Belém/PA. Designed 15 years ago, it is still in production, but needs to evolve to meet the new demands of user institutions. One of the obstacles to this evolution is the difficulty in carrying out tests to verify new configurations and adoption of new technologies. An innovative approach to overcoming these challenges is the use of Digital Shadow to address real-world problems. This approach uses digital techniques to represent real-world objects, has been gaining popularity in the industry and is beginning to be used in different scenarios. This paper proposes a four-step strategy to create a Digital Copy as an alternative to planning and evaluating computer networks. A case study of the MetroBel network is carried out to validate the proposal.

تركز هذه الدراسة على تحسين أداء نظام اتصال ضوئي مترابط يستخدم التعديل 16-QAM وبمعدل نقل بيانات 10 Gb/s عند زيادة مسافة الإرسال، من خلال تعويض التشتت اللوني الذي يؤثر على الإشارة المنتشرة في الألياف الضوئية أحادية النمط SMF، باستخدام معوضات التشتت. حيث تم دراسة نموذجًا لتعويض التشتت يتكون من شبكة انعراج براغ ذات الزقزقة الخطية Chirped Fiber Bragg Grating CFBG ويتبعها أربع مراحل متطابقة متتالية من شبكة انعراج براغ الموحدة Uniform Fiber Bragg Grating UFBG. تم تقييم أداء النظام من خلال حساب معدل خطأ البت وذلك في حال اختلاف طول شبكة الانعراج عند قيمة ثابتة لقرينة الانكسار الفعال لتحديد طول الشبكة المناسب وعند زيادة طول الليف الضوئي. وقد بينت المحاكاة من خلال برنامج Optisystem.19 تحسن في أداء النظام عند استخدام معوضات FBG إضافة إلى إمكانية زيادة طول الليف الضوئي حتى 180 km مع بقاء BER ضمن حدود مرتبة 10-3.

Padrões espaço-temporais trazem conhecimento de sequências de eventos, local e momento em que ocorrem. Encontrar tais padrões é uma tarefa complexa e de grande valor para diferentes domínios. No entanto, nem todos os padrões são frequentes em todo um conjunto de dados, ocorrendo com frequência em espaço e tempo restritos. Este trabalho formaliza a Mineração de Sequências Restritas no Espaço e no Tempo, sem o uso de limiares de restrição para tempo e espaço. Isso permite que diferentes tamanhos de sequências, intervalos de tempo e espaço tridimensional apresentem tais padrões. Traz também validação com uma implementação testada sobre um conjunto de dados sísmico real. Tendo como resultado uma análise de sensibilidade e avaliação do uso de recursos que indicam a validade e viabilidade da solução.

Trong những năm gần đây, các ứng dụng sử dụng hệ thống Internet vạn vật - IoT (Internet of Things) đang ngày càng phát triển bởi khả năng mềm dẻo trong thiết kế phần cứng và thu thập dữ liệu. Tuy nhiên, độ ổn định theo thời gian và tính bảo mật từ các hệ tự thiết kế không cao. Bài báo trình bày một phương pháp thiết kế hệ IoT theo chuẩn công nghiệp nhằm tăng cường bảo mật và duy trì tính ổn định cho hệ thống. Một mạng SCADA điều khiển PLC S7-1200 thông qua chuẩn KepServerEx được sử dụng để giám sát thu thập dữ liệu từ các trạm bơm. Kết nối mạng riêng ảo virtual private network (VPN) được dùng để truyền tín hiệu điều khiển và thu thập dữ liệu máy chủ về các trạm và ngược lại. Ngoài ra, hệ thống còn có thể đăng nhập từ bên ngoài thông qua chức năng truy cập từ xa. Kết quả cho thấy hệ thống hoạt động ổn định và có thể thu thập dữ liệu theo thời gian thực. Kết quả của bài báo này là tiền đề để tiến hành các nghiên cứu chuyên sâu hơn về lĩnh vực IoT theo chuẩn công nghiệp. 

The health sector in Kenya is one of the key segments that provide the most essential services to the public. Unmatched skills set to job requirement has been found to have a significant impact on performance of employees and the sector in general. Effectiveness of employee training and development programs such as job rotation can bridge the gap between job requirements and employees' ability to perform. However, it is not yet clear to what extent job rotation techniques can influence employee performance. The study therefore sought to assess the relationship between job rotation and employee performance in Level Four Hospitals operating within the South-Rift Region in Kenya. It was anchored on human capital theory, knowledge-based theory of the firm and social learning theory. Correlational and survey research designs were employed with a target population of 663 medical personnel drawn from 13 Level Four Hospitals. A sample size of 249 was determined while stratified simple random sampling method used to pick the respondents. Data was collected by use of structured a questionnaire whose reliability was tested through a pilot study where an average Cronbach alpha coefficient of 0.8102 was obtained. Content, construct and face validity were ensured by carrying out a detailed literature review and consultation with subject experts. Descriptive statistics comprising mean and standard deviation were used to categorize data while the study hypothesis was tested using correlation coefficient. The findings were presented in form of tables. The study established that job rotation had a moderate relationship (R = 0.506, β 1 = 0.406, R 2 =0.256, p<0.05) with employee performance indicating that Level Four Hospital in South-Rift region should invest in job rotation strategies. The study recommended that Level Four Hospitals in the South-Rift rotate personnel within the job function as it contributes more to their development. The findings may be useful to hospital management, human resource departments, scholars and researchers in in the field of human resources management.

A transmissão digital em banda base é um aspecto crucial dos sistemas de comunicação modernos, envolvendo a transmissão de sinais digitais sem modulação sobre um canal de comunicação. Nesse processo, dados binários, frequentemente representados como 0s e 1s, são transmitidos diretamente sobre o canal sem qualquer modulação para alterar as características do sinal.

A transmissão geralmente envolve a codificação, onde os dados digitais são convertidos em um formato específico adequado para a transmissão. Em seguida, o sinal codificado é enviado pelo meio de comunicação. A ausência de modulação simplifica o processo de transmissão, tornando-o mais direto e eficiente.

Aspectos-chave da transmissão digital em banda base incluem a formatação de pulso, codificação de linha e técnicas de detecção/correção de erros para aprimorar a confiabilidade da transmissão de dados. A formatação de pulso garante que o sinal transmitido atenda a certos critérios, reduzindo a interferência entre símbolos. A codificação de linha transforma os dados binários em uma forma de onda específica adequada para a transmissão sobre o canal.

A Conversão Analógico-Digital (CAD) é um processo fundamental no qual sinais analógicos contínuos são transformados em representações digitais discretas. Essa conversão é essencial em várias aplicações, como telecomunicações, processamento de áudio e sistemas de aquisição de dados. O processo de CAD envolve duas etapas-chave: amostragem e quantização. Durante a amostragem, o sinal analógico contínuo é amostrado de forma discreta em intervalos regulares. Os valores amostrados são então quantizados, atribuindo a cada amostra um código digital específico. A precisão da quantização determina a precisão da representação digital. Maior precisão resulta em uma representação mais fiel, mas exige mais bits para a codificação. A saída digital pode ser transmitida, processada ou armazenada de forma eficiente, beneficiando-se da resistência a ruídos e facilidade de manipulação. O processo inverso, Conversão Digital-Analógica (CDA), é utilizado para converter sinais digitais de volta para analógicos quando necessário. Compreender e otimizar as técnicas de CAD é crucial para manter a integridade do sinal e garantir a confiabilidade de sistemas digitais que se comunicam com o mundo analógico.

Resumo-Neste artigo é apresentada uma arquitetura para o multiplicador de Mastrovito usando circuitos de limiar linear. São determinados os polinômios irredutíveis ótimos para a construção do multiplicador de Mastrovito em corpos finitos GF (2 m), para 2 ≤ m ≤ 16. A arquitetura proposta fornece menor complexidade espacial teórica em relação às outras arquiteturas do multiplicador de Mastrovito. Quando há a utilização de polinômios irredutíveis ótimos, observa-se uma redução da complexidade espacial para m > 11.

Resumo-Alcançabilidade justa é um método de análise lógica útil na detecção de erros de progresso em protocolos de comunicação representados por MEFCs. É imprescindível a análise lógica do LMP que é um dos protocolos que constituem o GMPLS. Assim, verifica-se o comportamento deste bem como se o mesmo está ou não livre de erros de progresso.

In this paper, we thoroughly investigate the impact of black hole attacks under Ad hoc On-Demand Distance Vector (AODV) routing in smart metering network. Specifically, the impact of black hole attack is fully examined by adjusting AODV parameters such as Hello message interval, route lifetime and positions of malicious meters, which have been under explored so far. Two critical performance metrics including packet delivery ratio and end-to-end delay are used to measure the impact. Extensive simulations are conducted in a topology based on an actual suburban neighborhood. Simulation results demonstrate that by carefully adjusting AODV parameters, it increases resistance against black hole attack. The position of malicious meters also plays a critical role to prevent black hole attack and is studied as well.

Resumo-Alcançabilidade justa é um método de análise lógica útil na detecção de erros de progresso em protocolos de comunicação representados por MEFCs. É imprescindível a análise lógica do LMP que é um dos protocolos que constituem o GMPLS. Assim, verifica-se o comportamento deste bem como se o mesmo está ou não livre de erros de progresso.

Resumo-Este trabalho estuda os problemas decorrentes da coexistência dos fluxos TCP e UDP em redes de dados, tendo em vista o observado aumento do volume de tráfego transportado via UDP nosúltimos anos. Nossa propostaé que os fluxos UDP, por não serem cooperativos, sejam penalizados via tarifação de acordo com o impacto causado no tráfego TCP. Algoritmos de controle de admissão e roteamento são propostos de forma a regularem o tráfego UDP minimizando o estrangulamento do TCP e garantindo também a QoS necessária aos fluxos UDP. Resultados da simulação mostram as vantagens da proposta quando comparada com o cenário atual da Internet. Palavras-Chave-qualidade de serviço, coexistência TCP-UDP, controle de congestionamento, controle de admissão, função utilidade Abstract-This work studies the coexistence of TCP and UDP flows in data networks. Our proposal is that UDP flows are penalized, through a dynamic charging scheme, according to the impact caused on TCP traffic. Admission control and routing algorithms are proposed to regulate UDP traffic minimizing TCP starvation and providing the required QoS for UDP flows. Simulation results show the advantage of our proposal when compared to current procedures in the Internet scenario.

Intelligent Reflecting Surfaces (IRS), is an emerging technology in wireless communications due to the spectral and power efficiency they tout. These are structures that are composed of multiple antenna patches that can actively or passively control the redirection of electromagnetic waves incident on them, changing phase and amplitude as per use. This causes them to see the use in various wireless communication systems, where they can Substantiate and improve upon existing multiplexing techniques. This paper presents a review of the developments in these applications and goes on to present a systematic review of the results that they have yielded. 

Intelligent Reflecting Surfaces (IRS), is an emerging technology in wireless communications due to the spectral and power efficiency they tout. These are structures that are composed of multiple antenna patches that can actively or passively control the redirection of electromagnetic waves incident on them, changing phase and amplitude as per use. This causes them to see the use in various wireless communication systems, where they can Substantiate and improve upon existing multiplexing techniques. This paper presents a review of the developments in these applications and goes on to present a systematic review of the results that they have yielded.

The health sector in Kenya is one of the key segments that provide the most essential services to the public. Unmatched skills set to job requirement has been found to have a significant impact on performance of employees and the sector in general. Effectiveness of employee training and development programs such as job rotation can bridge the gap between job requirements and employees' ability to perform. However, it is not yet clear to what extent job rotation techniques can influence employee performance. The study therefore sought to assess the relationship between job rotation and employee performance in Level Four Hospitals operating within the South-Rift Region in Kenya. It was anchored on human capital theory, knowledge-based theory of the firm and social learning theory. Correlational and survey research designs were employed with a target population of 663 medical personnel drawn from 13 Level Four Hospitals. A sample size of 249 was determined while stratified simple random sampling method used to pick the respondents. Data was collected by use of structured a questionnaire whose reliability was tested through a pilot study where an average Cronbach alpha coefficient of 0.8102 was obtained. Content, construct and face validity were ensured by carrying out a detailed literature review and consultation with subject experts. Descriptive statistics comprising mean and standard deviation were used to categorize data while the study hypothesis was tested using correlation coefficient. The findings were presented in form of tables. The study established that job rotation had a moderate relationship (R = 0.506, β 1 = 0.406, R 2 =0.256, p<0.05) with employee performance indicating that Level Four Hospital in South-Rift region should invest in job rotation strategies. The study recommended that Level Four Hospitals in the South-Rift rotate personnel within the job function as it contributes more to their development. The findings may be useful to hospital management, human resource departments, scholars and researchers in in the field of human resources management.

Página 38 Tanto o controle do CDV quanto a compensação de perda e inserção. de células são efetuactos com a implementação de um buffer no terminal receptor. No caso de atraso excessivo (underflow) ou de perda de células, unidades de dados são geradas e inseridas pela AAL ou, no caso de antecipação relativa ou de inserção de células, unidades de dados são descartadas. O preenchimento da célula pode causar retardo significativo na comunicação. Para reduzir este atraso, células parcialmente preenchidas podem ser usadas, o que por outro lado custa banda adicional. A opção de preenchimento parcial pode ser configurada no provisionamento da conexão ATM (se PVC) ou por sinalização (se SVC). Recuperação de sincronismo Existem dois mecanismos para a recuperação do relógio da fonte: o SRTS (Synchronous Residual Time Stamp) e o adaptativo. Este métQdossão ilustrados na Figura 3-6. Esta função pode também ser implementada de forma proprietária nas camadas superiores de protocolo, neste caso dispensando qualquer mecanismo na camada AAL.

In 2008, a pilot project initiated by TGE Adonis, a large research infrastructure, brought together designers of data repositories, archivists and system engineers to set up collaborative oral/linguistic resource centres in France. This paper discusses challenging issues addressed by this team when implementing an Open Archival Information System (OAIS) bundled with an institutional archive. After the completion of the pilot project, the Speech & Language Data Repository (SLDR) underwent development for the systematic management of access rights in compliance with the French Heritage code. Its framework claims to be applicable to other systems worldwide, which would facilitate interoperability between protected repositories equipped with transfer of authentication techniques (Single Sign-On). 1 Project documents, reports and evaluation are stored in the archive: www.sldr.org/ark:/87895/1.4-187408 2 Legal statements were signed in June 2010 between the CNRS, CINES and DAF (the French National Archive) after the evaluation (Marcoux, 2009) and presentation of the pilot project (Pouyllau, 2009).

ORTOLANG é éfi ie d'u e aide de l'Etat au tit e du p og a e « I vestisse e ts d'ave i » (ANR-11-EQPX-0032) http://sldr.org/doc/show/SLDR-PR2I.pdf Qui ous so es… La Banque de données parole et langage, Speech & Language Data Repository (SLDRwww.sldr.org) est un service générique de mutualisation et archivage de données numériques créé par le Laboratoire Parole et Langage (LPL, UMR 7309 CNRS-AMU). L o je tif du SLDR était de regrouper les ressources linguistiques associées à la communication orale/multimodale. Une telle centralisation permet tout d a o d d vite que les laboratoires travaillant dans ce domaine ne soient conduits à recréer sans cesse des données. La mutualisation de ressources en sciences du langage répond par ailleurs au besoin stratégique de rapprocher les connaissances aujou d hui dispersées dans des domaines variés comme la linguistique descriptive, formelle et computationnelle, la sociolinguistique, la littérature, la traductologie, les neurosciences, la psycholinguistique etc.

T his series focuses on softwarization, management, and their integration in communication networks and services. "Network Softwarization" advocates for network architectures that separate the software implementing network functions, protocols and services from the hardware running them. "Network Management" aims to integrate fault, confi guration, accounting, performance, and security capabilities in the network and to support self-management features, integral automation, and autonomic capabilities, empowering the network with inbuilt cognition and intelligence. The critical role that software and management are increasingly playing in telecommunications is enabling unprecedented levels of abstraction, disaggregation, operation, integration, robustness, optimization, intelligence, precision delivery, programmability, and cost and complexity reduction in the network infrastructures and services. Such an approach is resulting in even greater attainment of non-functional characteristics (e.g., qualities of the operation of a network, rather than specific behaviors including flexibility, integrability, interoperability, operational guarantees, deployability, auditability and control, reliability, adaptability, elasticity, eff ectiveness, extensibility, automation and autonomicity). This series selects and publishes in-depth, cutting-edge articles on state-of-the-art technologies and solutions bringing together the latest advances, technical innovations, opensource projects, case studies, research, and development in Network Softwarization and Management in terms of main paradigms and systems, architectures and methodologies, software approaches, resources, functions, modelling, measurement, performance analysis and cyber-networking. This series also welcomes experience reports from experimental testbeds, Network Softwarization and Management standards, open-source projects, and solutions. Softwarization and management would help innovate network and cloud-network tasks, accelerate service deployment, and facilitate infrastructure management efficiency. Artificial Intelligence (AI)/Machine Learning (ML) based awareness and resolutions would be applied to address the complexity proliferating rapidly, making current network control and management techniques based on analytical models and simulations impractical. Slicing across access, core and edge networks, multi-domain networks, and cloud would

Wireless Body Area Network (WBAN) is a new trend in the technology that provides remote mechanism to monitor and collect patient's health record data using wearable sensors. It is widely recognized that a high level of system security and privacy play a key role in protecting these data when being used by the healthcare professionals and during storage to ensure that patient's records are kept safe from intruder's danger. It is therefore of great interest to discuss security and privacy issues in WBANs. In this paper, we reviewed WBAN communication architecture, security and privacy requirements and security threats and the primary challenges in WBANs to these systems based on the latest standards and publications. This paper also covers the state-of-art security measures and research in WBAN. Finally, open areas for future research and enhancements are explored.

This article is in order to show the main features of the OTN transport network in the optical layer. Index Terms-Optical layer, optical networks, OTN and optical transmission standard. Resumo-Este artigo tem como objetivo apresentar as principais características da rede de transporte OTN na camada óptica. Palavras chave-Camada óptica, redes óptica, padrão OTN e Transmissão óptica.

Processo 98/11731-4. RESUMO O programa de simulação do Canal de Controle Digital (DCCH) do Sistema Móvel TDMA (Acesso Múltiplo por Divisão Temporal) é apresentado neste trabalho. Essa simulação considera o diagrama de estado da estação móvel e é implementada a partir da descrição dos procedimentos de