Asymmetric digital subscriber line (ADSL) is a broadband access technology capable of delivering large bandwidth over existing copper telephone line infrastructure. This research aims at characterizing and analyzing TCP/IP performance in presence of a new protocol stack (TCP/IP over PPP and ATM) being promoted for one of the ADSL network architectures. Using extensive simulations, we verify the adverse effects of asymmetric links on the performance of TCP and additional throughput degradation caused by the overhead at the AAL5- ATM layers. This study involves unidirectional as well as bi-directional data transfer using different traffic mixes including bursty and non-bursty types of traffic. Bi-directional data transfer over asymmetric links results in ACK compression wherein TCP acknowledgements (ACKs) get bunched together behind larger data packets, further exacerbating the effect of asymmetry on TCP performance. By implementing the simulation model for PPP encapsulation over AAL5, we characterize its effect in terms of throughput degradation and excessive delay. We quantify the improvement in the throughput obtained by delaying the TCP ACKs and by TCP/IP header compression. These techniques being effective for unidirectional traffic over asymmetric links, however, do not prove as effective when ATM enters the scenario or in presence of bi-directional data transfer. Further, we implemented a simulation model of the Smart ACK Dropper (SAD), a technique to regulate the flow of TCP ACKs. Considerable improvement in performance especially in the presence of unidirectional data transfer is achieved using the SAD technique. Although the improvement is to a lesser extent in the presence of bi-directional data traffic, SAD helps the network in quickly recovering from the impact of ACK compression. We also propose and implement certain customized queuing/scheduling and policing mechanisms to enable differentiated servicing of TCP ACKs and data packets, and mitigate the effect of ACK compression. While providing considerable TCP performance improvement in presence of SAD, custom queuing also allows fair sharing of bandwidth between TCP flows, unlike priority queuing, which starves the low priority flow. The committed access rate (CAR)policing scheme provides considerable performance improvement when used with SAD, and is especially useful when TCP ACKs compete with bursty data traffic over the slower upstream. / Master of Science

Με την εργασία αυτή γίνεται μια οικονομική αξιολόγηση ενός ευρυζωνικού δικτύου πρόσβασης μέσα από την ανάπτυξη ενός προγράμματος (σε κώδικα C) που σαν εισόδους έχει την διείσδυση της κάθε υπηρεσίας στην αγορά, δηλαδή τον αριθμό των πιθανών συνδρομητών, τα στοιχεία της περιοχής, τον εξοπλισμό του δικτύου που πρόκειται να εγκατασταθεί, καθώς και οικονομικά στοιχεία όπως η χρέωση για την υπηρεσία από τον πάροχο. Χρησιμοποιώντας τα στοιχεία αυτά η εφαρμογή υπολογίζει την Καθαρή Παρούσα Αξία (NPV) τον Εσωτερικό Ρυθμό Επιστροφής (IRR) καθώς και την Παρούσα Αξία Ετήσιων Δαπανών (PVAC) για ένα χρονικό ορίζοντα δέκα ετών. Επίσης για την κοστολόγηση του δικτύου υπολογίζει τον συνολικό εξοπλισμό που χρειάζεται να εγκατασταθεί, κάνοντας μια εκτίμηση, προς την χειρότερη πλευρά, για τα μέτρα της οπτικής ίνας που χρειάζεται να τοποθετηθεί. Συγκρίνοντας τα αποτελέσματα των NPV για έτος εκκίνησης διαφορετικό κάθε φορά παρουσιάζει το έτος που ένας πάροχος θα πρέπει να εγκαταστήσει το δίκτυο του έτσι ώστε στο τέλος του χρονικού ορίζοντα να έχει το μέγιστο δυνατό κέρδος. Στα πρώτα κεφάλαια γίνεται μια θεωρητική παρουσίαση των διαθέσιμων τεχνολογιών πρόσβασης και του εξοπλισμού, ενώ στα δύο τελευταία κεφάλαια παρουσιάζεται το πρόγραμμα και τα αποτελέσματα για τέσσερα υποθετικά σενάρια. / -

Diplomová práce se zabývá problematikou rozvoje širokopásmového připojení (broadbandu) k Internetu v České republice. Snaží se odpovědět na otázky nízké penetrace domácností Internetem u nás a překážek jejího rozvoje. Práce ve své úvodní části obsahuje analýzu v Česku nejrozšířenějších dostupných možností připojení k Internetu a jednotlivých nabízených služeb včetně formulace nutných podmínek na trhu pro rozvoj broadbandu v ČR. Na tuto analýzu navazuje kapitola trendů v oblasti broadbandu, tedy pohled na plány významných subjektů v Česku i ve světě, na současnou do jisté míry latentní poptávku po službách využívajících broadband infrastrukturu a projektované zákaznické potřeby. Z této analýzy vyplývají důležité závěry, které jsou následně využity pro formulaci doporučení v podobě klíčových faktorů úspěchu firem působících na broadband trhu. Další text práce se rovněž zabývá současným stavem GTS Novera a dívá se i na její veřejně dostupné plány dalšího rozvoje. Načerpané teoretické znalosti jsou následně použity ke zpracování samotného přínosu práce, jímž je case studie zasíťování modelového pražského sídliště broadband infrastrukturou a navržení reálného technicko-ekonomicko-obchodního modelu pro společnost GTS Novera k realizaci byznys plánu v těchto konkrétních podmínkách. Následně jsou tyto výsledky zasazeny do rámce studie návratnosti investice s návrhem nových služeb pro další rozvoj společnosti GTS Novera.

This report is about a Thesis for Degree of Bachelor of Science at Linköping University. It describes design of equipment which makes it possible to measure signal and noise quality during data transmission via Asymmetric Digital Subscriber Line, ADSL. The measuring instrument is HP 4934A Transmission Impairment Measuring Set. The equipment was supposed to be used for testing of ADSL systems within Solectron Sweden AB. In fact, the equipment stands for virtual Plain Old Telephone Service, POTS. That is why it simulates all three states that may come up. The states are following:"on hook", ringing,"off hook"(speech transmission). There is a control unit in the design. It changes between different circuit connections to get one of the states. You have to use a computer for control of the equipment. The computer commands are sent to equipment via its serial port via RS232 to the control unit. The equipment is driven with 48 Vdc.

This thesis proposes a pricing model for Internet access services. Firstly, demand, pricing and costing practices in communications sector are briefly explored. Then a pricing model for the ADSL Internet access service by T&uuml / rk Telekom is described. The model uses the demand and cost information of a specific service and price is assumed as the key input. The model tries to find the optimum level of prices that maximize the profits under certain constraints regarding the network and customer concerns. The model and its output are discussed in comparison with the international cases and the scope of the further study is addressed in line with the developments occurring in the broadband access market.

Title of Thesis¡GService Quality and Customer Satisfaction of ADSL Broadband Network¡GA Case Study of Chunghwa Telecom Total Pages¡G108 Name of Institute¡GGraduate Institute of Information Management National Sun Yat-Sen University Graduate date¡GJune,2002 Advisor¡GChin-fu Ho Name of Student¡GWen-Jong Leu Abstract The open telecom market causes the telecom business to be competitive and obvious and each telecom company invests an amount of cost to gain more customers. As a result of the increase in consumer consensus, most telecom companies are dedicated to create a variety of newer, faster and more stable telecom products and consistently lower the prices. Besides, in order to sustain loyal customers and attract new customers, providing high-quality service becomes the most important strategy. Even though Chunghwa Telecom today has taken a great part in ADSL market, it should think much of customers and make an effort to provide them with good ADSL broadband network products¡Bservice quality and satisfactory service to defend and enlarge the market. This thesis discusses ADSL broadband network, service quality, customer satisfaction and the development of Chunghwa Telecom. The structure of this study is constructed based on the concept to SERVQIAL submitted by three scholars like Parasuraman(PZB) and the research on the users of Chunghwa Telecom ADSL in Kaohsiung area with the analytic tool of SPSS software.The purpose of this study is to discuss the difference between customers expectations and recognition and examine the relevance between service quality factor and customer satisfaction. The Conclusion of This Study: 1. Customers' expectations to ADSL are not compatible with their recognitions because ADSL service is not as good as what they expect. Customers also expressed that the performance of Chunghwa Telecom didn't reach their expectations. 2. The relationships between customers perceived degree of ADSL overall service quality, ADSL service quality factor perceived degree, and overall satisfaction are positively relevant. In other words, customers have more perceived degree of ADSL overall service quality or five factors perceived degree of ADSL service quality, including "Tangibility," "Reliability," "Responsiveness," "Assurance," and "Empathy," then customers are more satisfied with the ADSL overall satisfaction. 3. Based on the variable of population statistics on customers, different ages distinctively have diverse perceived degree of ADSL overall service quality. Furthermore, this result is reflected on the relationship between the ages and ADSL service quality five factors perceived degree. Customers at the age of under 20 and from 20 till 40 have much more different perceived degree of ADSL overall service quality and five factors. 4. Based on the variable of population statistics on customers, only sex difference causes different overall satisfaction with ADSL service. Male customers are more satisfied with the service than female ones. Therefore, telecom companies like Chunghwa Telecom should improve service quality, especially to female customers. Besides, customers with different sexes have different perceived degree of one factor on ADSL service quality, "Responsiveness," but the other four factors have no obvious difference.

<p>This report is about a Thesis for Degree of Bachelor of Science at Linköping University. It describes design of equipment which makes it possible to measure signal and noise quality during data transmission via Asymmetric Digital Subscriber Line, ADSL. The measuring instrument is HP 4934A Transmission Impairment Measuring Set. The equipment was supposed to be used for testing of ADSL systems within Solectron Sweden AB. In fact, the equipment stands for virtual Plain Old Telephone Service, POTS. That is why it simulates all three states that may come up. The states are following:"on hook", ringing,"off hook"(speech transmission). There is a control unit in the design. It changes between different circuit connections to get one of the states. You have to use a computer for control of the equipment. The computer commands are sent to equipment via its serial port via RS232 to the control unit. The equipment is driven with 48 Vdc.</p>

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia de Produção. / Made available in DSpace on 2012-10-21T09:56:39Z (GMT). No. of bitstreams: 1 225550.pdf: 2093579 bytes, checksum: e161828cbde57dc1147e60e63a579d24 (MD5) / A avalanche de transformações sociais advindas da era da tecnológica e do uso da Internet, aqui especificamente, via ADSL (Asymmetric Digital Subscriver line) ativaram oportunidades, proporcionando mudanças. A competição é agora global; as respostas variam de empresa para empresa, de indivíduo para indivíduo,dependendo da história (da empresa do indivíduo) e do contexto social, político, econômico, cultural da atualidade; e surge um ambiente empresarial caracterizado pela falta de equilíbrio. Assim, este trabalho teve como objetivo principal analisar a tecnologia cibernética em geral e da ADSL como inovação na ótica dos ciclos de Kondratieff da economia, tendo em vista os resultados observáveis nos últimos dez anos e suas potencialidades. Através de consulta bibliográfica, levantou-se os tipos de acesso existentes na Internet, identificando, através de questionário, o perfil dos usuários de acesso a ADSL da operadora em telefonia fixa, propondo-se novos negócios agregados à tecnologia ADSL (através de um Estudo de Caso). Apresentaram-se também as inovações em geral das redes de acesso à Internet por banda larga, bem como a via ADSL e o possível novo ciclo de Kondratieff. Para isso, fez-se necessário pesquisar junto à bibliografia existente e aos clientes quais as suas expectativas quanto ao uso da Internet (preço, velocidade, dentre outros). O objetivo geral, nesta linha de raciocínio, é verificar as reais necessidades dos clientes que utilizam esta tecnologia, e verificar através delas, um novo modelo que contemple as necessidades do público-alvo. Enfatizando que, nesta nova era, as empresas têm de se ajustar aos seus clientes para haver evolução no contexto empresarial, no desenvolvimento, no incentivo e na preservação da capacidade empreendedora das pessoas, a fim de garantir a sobrevivência no mercado, satisfazendo o acionista e também o cliente. The huge amount of social transformations originated from the technological age and the Internet # specifically with the use of ADSL (Asymmetric Digital Subscriber Line) # have generated opportunities, thus causing changes. Competition is now global; answers vary from person to person, depending on each one#s history (company#s and individual#s) and of the social, political, economical and cultural context of the moment; an unbalanced business environment arises. The main purpose of this work is to analyze cybernetic technology in general and ADSL as innovations from the Kondratieff economic cycles perspective, considering the observable results of the 10 years and their potential. From bibliographic sources, internet access types were listed and the profile of ADSL users tracked making use of questionnaires. New business opportunities were proposed related to ADSL (a Case Study). Innovations on Broadband Internet access networks in general were also presented, as well as the ADSL way and the possible new Kondratieff cycle. In order to do that, it was necessary to research though existing bibliography and customers which were their expectations regarding the use of Internet (price, speed, etc.). The main objective from this point view was know what the customers that use this technology really need and propose from there a new model that encompasses the needs of the target population. In this new era, it is necessary to stress that the enterprises have to adjust themselves to their customers in order to promote the evolution of the business environment and the development, encouragement and protection of the enterprising capacity of people to guarantee market survival and satisfy both the shareholder and the customer.

El proyecto consiste en el rediseño del proceso de instalación de ADSL (Banda Ancha), con énfasis en los procesos de gestión de producción, en la entrega del servicio y de las actividades de apoyo que realiza la Plataforma de Gestión de las Instalaciones (PGI) para asistir al técnico en el momento de presentarse un problema o falla en la instalación. Dichos problemas pueden ir desde la inexistencia de un par de cobre en el armario para conectar al nuevo cliente hasta un cambio en el producto solicitado por parte del cliente al momento de la instalación. Para solucionar estas situaciones, el técnico debe contactarse vía telefónica con la PGI, donde una operadora realizará las gestiones que se requieran para resolver dicho problema en la instalación. Como respuesta a esta problemática, se diseñó una solución de auto-atención utilizando un dispositivo inalámbrico, el cual permite conectividad con los sistemas de Telefónica, permitiendo autonomía y resolución de las distintas situaciones que se presentan en la casa del cliente. Para el modelamiento, tanto de la situación actual como la mejorada, se utiliza la metodología desarrollada por el Dr Oscar Barros para el rediseño de los procesos de negocios con soporte de Tecnologías de la Información. Además se utiliza el FrameWork Etom, el cual ha sido diseñado por un conglomerado de las empresas de Telecomunicaciones más importantes a nivel mundial. En él se plasma las actividades y procesos que debiera tener y realizar una empresa de telecomunicaciones “modelo” en la industria. Como resultado de éste proyecto se obtuvo el ordenamiento de los procesos actuales de la PGI, resolución por tipología, generación de data necesaria para realizar análisis sobre dichas ocurrencias y mejor percepción por parte de los clientes al momento de instalar. Se obtuvieron reducciones de hasta un 50% en llamadas no atendidas y segundos llamados, lo cual se traduce en ahorros de $6 Millones por este concepto y se generan facturaciones tempranas por montos de $9.5 Millones mensuales sólo por ADSL.

This master’s thesis is focused on the problems of designing telephone lines which are 7 km long with a step of 1 km. The thesis contains a detailed description of the basic parameters of metallic transmission lines. There is also briefly mentioned the issue of interfering the transmission lines. The main part is devoted to a system design of artificial lines connection, including printed circuit board design. The next section deals with a design of prototype controlling. The last part verifies the activity of implemented artificial lines.