Multimedia data capture with multicast dissemination for online distance learning

Distance Learning Environments (DLEs) are elusive to define, difficult to successfully implement and costly due to their proprietary nature. With few open-source solutions, organizations are forced to invest large amounts of their resources in the procurement and support of proprietary products. Once an organization has chosen a particular solution, it becomes prohibitively expensive to choose another path later in the development process. The resolution to these challenges is realized in the use of open-standards, non-proprietary solutions. This thesis explores the multiple definitions of DLEs, defines metrics of successful implementation and develops open-source solutions for the delivery of multimedia in the Distance Learning Environment. Through the use of the Java Media Framework API, multiple tools are created to increase the transmission, capture and availability of multimedia content. Development of this technology, through the use of case studies, leaves a legacy of lectures and knowledge on the Internet to entertain and enlighten future generations.http://archive.org/details/multimedidatcapt109456185US Navy (USN) autho

Integração de uma access gateway control function num cenário TISPAN

Mestrado em Engenharia Electrónica e TelecomunicaçõesLonge vão os tempos em que as comunicações se encontravam quase exclusivamente limitadas a soluções disponibilizadas pela rede telefónica tradicional (também designada de PSTN – Public Switched Telephone Network). A enorme popularização da Internet levou ao aparecimento de um novo conceito denominado de “tudo-sobre-ip” permitindo na mesma plataforma transportar voz, dados e vídeo. Surgem então as NGN (Next Generation Networks), que apresentam uma arquitectura baseada em IP e estruturada de uma forma revolucionária isto é, em camadas horizontais. Um dos serviços que mais interesse tem despertado é o Voice over IP (VoIP). No entanto, tendo em conta o enorme número de utilizadores da rede telefónica tradicional e todas as infra-estruturas dos operadores que sustentam esta rede de comutação de circuitos não é de todo recomendável que a migração para as NGN seja realizada de modo repentino. Esta deve ser efectuada de uma forma faseada, sendo necessário dar continuidade ao serviço PSTN e a outras redes de acesso, criando-se uma rede comum e aberta, visando a convergência fixomóvel. Uma das soluções propostas para a arquitectura deste tipo de rede proveio do TISPAN. Esta, por sua vez, baseia-se na solução IMS do 3GPP, mas diferencia-se especialmente através do seu subsistema PES que permite a emulação da rede telefónica PSTN/ISDN de forma transparente. Para que seja possível a interligação dos elementos POTS, que utilizam protocolos específicos como o SS7, ao core NGN, é necessária a existência de um elemento intermédio – Access Media Gateway (A-MGW) – e outro que efectue o seu controlo. No caso do subsistema PES, esta entidade designa-se de Access Gateway Control Function (AGCF). O presente trabalho propõe-se divulgar as características da arquitectura NGN apresentada pelo TISPAN, dando especial ênfase ao subsistema PES e à AGCF que foi desenvolvida no âmbito desta dissertação. A pretensão de introduzir este elemento num demonstrador de arquitectura NGN específico, designado de Service Handling on ip NETworks (SHipNET®) levou a que fossem efectuados diversos testes com o intuito de averiguar o bom funcionamento da solução implementada referente às seguintes capacidades: configuração inicial, registo/desregisto, chamada. ABSTRACT: The traditional standard of telephone network (known as PSTN) is nowadays no longer exclusive for communication. The enormous spread of the Internet led to a new concept known as "all over IP", allowing voice, data and video to be transmitted on the same level of platform. The NGN come from this purpose and present an architecture based on IP and is structured from an advanced way: horizontal levels. One of the services that has most success is the Voice over IP (VOIP). However, as the number of the traditional telephone network customers is still significant, it is obviously quite impossible a sudden transition to the new model. Instead, it should be done step by step and not negleting the PSTN service and the other types of access. This way, a common network will be implemented with the purpose of creating a convergence in both of them, which means, fixed-mobile. One of the proposed answers viewing the implementation of this type of net, came from the TISPAN, which is based on the IMS solution from the 3GPP. Nevertheless, it differs from it on its PES subsystem, which allows the emulation of the telephone network PSTN/ISDN in a simple way. In order to make it possible the access of the POTS (using protocol demands, such as SS7) to the core NGN, it is necessary an intermediate element - Access Media Gateway (A-MGW) - and another one to do its control. In relation to the PES subsystem, this element is called Access Gateway Control Function (AGCF). This research aims to make it possible the knowledge of the NGN architecture proposed by TISPAN, placing special emphasis on the PES subsystem and also on the AGCF, being developed in this dissertation. The purpose of including this element in a demonstration of NGN architecture, known as Service Handling on ip Networks (SHipNET®), was to examine - through several tests, such as initial configuration, registry/desregistry, call - how the solution runned