Towards automated test and validation of SIP solutions

IP networks are currently the major communication infrastructure used by an increasing number of applications and heterogeneous services, including voice services. In this context, the Session Initiation Protocol (SIP) is a signaling protocol widely used for controlling multimedia communication sessions such as voice or video calls over IP networks, thus performing vital functions in an extensive set of public and enter- prise solutions. However, the SIP protocol dissemination also entails some challenges, such as the complexity associated with the testing/validation processes of IMS/SIP networks. As a consequence, manual IMS/SIP testing solutions are inherently costly and time consuming tasks, being crucial to develop automated approaches in this specific area. In this perspective, this article presents an experimental approach for automated testing/validation of SIP scenarios in IMS networks. For that purpose, an automation framework is proposed allowing to replicate the configuration of SIP equipment from the pro- duction network and submit such equipment to a battery of tests in the testing network. The proposed solution allows to drastically reduce the test and validation times when compared with traditional manual approaches, also allowing to enhance testing reliability and coverage. The automation framework comprises of some freely available tools which are conveniently integrated with other specific modules implemented within the context of this work. In order to illustrate the advantages of the proposed automated framework, a real case study taken from a PT Inovação customer is presented comparing the time required to perform a manual SIP testing approach with the one time required when using the proposed auto- mated framework. The presented results clearly corroborate the advantages of using the presented framework.

Quantifying, generating and mitigating radio interference in Low-Power Wireless Networks

Doctoral Programme in Telecommunication - MAP-tele

E-government e participação política em Portugal

Dissertação de Mestrado em MPA - Administração Pública

A Model of Video Traffic Transmission in IP Networks

Telecommunications and network technology is now the driving force that ensures continued progress of world civilization. Design of new and expansion of existing network infrastructures requires improving the quality of service(QoS). Modeling probabilistic and time characteristics of telecommunication systems is an integral part of modern algorithms of administration of quality of service. At present, for the assessment of quality parameters except simulation models analytical models in the form of systems and queuing networks are widely used. Because of the limited mathematical tools of models of these classes the corresponding parameter estimation of parameters of quality of service are inadequate by definition. Especially concerning the models of telecommunication systems with packet transmission of multimedia real-time traffic.

Estudio de las diferentes alternativas para mejorar la respuesta de los filtros BAW (Bulk Acoustic Wave) con topología en escalera

Los requisitos de los dispositivos empleados en los nuevos sistemas de telecomunicaciones son: unas avanzadas prestaciones, reducido tamaño y bajo coste. Actualmente, se utilizan filtros basados en la tecnología SAW para trabajar a frecuencias de microondas. Dado los inconvenientes que presentan dicho tipo de filtros, se pretende substituirlos por filtros basados en tecnología BAW. La topología en escalera es hasta el momento la más extendida para diseñar estos filtros.

Creation of a carrier-grade telco based on a voice over IP backbone

En aquesta memòria l'autor, fent servir un enfoc modern, redissenya i implementa la plataforma que una empresa de telecomunicacions del segle 21 necessita per poder donar serveis de telefonia i comunicacions als seus usuaris i clients. Al llarg d'aquesta exposició es condueix al lector des d'una fase inicial de disseny fins a la implementació i posada en producció del sistema final desenvolupat, centrant-nos en solucionar les necessitats actuals que això implica. Aquesta memòria cubreix el software, hardware i els processos de negoci associats al repte de fer realitat aquest objectiu, i presenta al lector les múltiples tecnologies emprades per aconseguir-ho, fent emfàsi en la convergència actual de xarxes cap al concepte de xarxes IP i basant-se en aquesta tendència i utilitzant aquesta tecnologia de veu sobre IP per donar forma a la plataforma que finalment, de forma pràctica, es posa en producció.

Desenvolupament d'eines per l'apliació de l'aprenentatge basat en projectes a l'enginyeria tècnica de telecomunicacions

El projecte d'innovació docent s'emmarca dintre de la línia de treball de l'Escola Politècnica Superior de Castelldefels. Aquesta escola, des de els seus inicis ha destacat per la seva aposta per la innovació docent i l'aplicació de mètodes pedagògics pioners arreu d'Espanya. El sistema d'ensenyament basat en el seguiment individualitzat de l'estudiant, facilitat per una bona relació professor/nombre d'estudiants (grups de 40 o 20 estudiants), l'avaluació continuada, que parteix de les activitats acadèmiques realitzades en una matèria, i l'avaluació curricular, que atén el rendiment global de l'estudiant, fan que el sistema fomenti el treball regular al mateix temps que l'informa en tot moment del seu progrés acadèmic. Per un altre banda, dintre del sistema educatiu de la nostra escola podem destacar l'aplicació de l'Aprenentatge Basat en Projectes (PBL), aplicat inicialment als estudis de Segon Cicle. D'acord amb aquest model, els alumnes aprenen realitzant projectes en grup. Les intervencions del professorat i els materials del curs estan orientats a donar suport a les necessitats dels projectes que es desenvolupen a cada moment. Tot seguint la línia de treball de l'escola i la seva adequació als criteris determinats en el Espai Europeu d'Educació Superior, aquest projecte segueix tres línies d’actuació: (1) incideix en l'aplicació del PBL dintre d'assignatures Optatives i en assignatures de primers cursos de la Titulació d'Enginyeria de Telecomunicacions, (2) estimular l’alumnat, a través de treballs interdisciplinaris i la utilització de les noves tecnologies, (3) generació de documentació adaptada als nous plans d’estudi. Aquestes línies d’actuació es desenvolupen per motivar els alumnes en els estudis d'enginyeria que estan cursant i fer-los veure l'aplicabilitat, en el camp de la recerca, de gran quantitat dels coneixements que van adquirint durant la seva formació dintre de la Universitat.

QUALITEL : Qualitat Docent als estudis d'Enginyeria de Telecomunicació

L'objectiu del projecte QUALITEL dut a terme durant el curs 2007/2008 fou millorar l'aprenentatge dels estudiants de primer curs (fase selectiva) d'enginyeria de telecomunicació de l'ETSETB, introduint una nova metodologia docent basada en l'EEES. Es a dir, programació del treball de l'estudiant dins i fora de l'aula, increment de la interacció entre el professors i els seus estudiants mitjançant un sistema de tutories i la utilització d'eines de suport a l'aprenentatge com la utilització del Campus Digital ATENEA. La millora de l'aprenentatge s'hauria de traduir en un augment significatiu del percentatge d'aprovats a la fase selectiva que permetés capgirar la dinàmica de l'ETSETB en els darrers anys que ha sofert una davallada molt important d'estudiants matriculats. Aquesta davallada es va originar per una disminució de la demanda dels nostres estudis, la qual va provocar una baixada de la nota de tall que, a la seva vegada, va comportar un elevat fracàs a la fase selectiva.

Títol del Treball Fi de Carrera

En aquest projecte s'ha desenvolupat un sistema de comunicació (xat) segur.

Evaluating the probability and the impact of a failure in GMPLS based networks

In this paper, we define a new scheme to develop and evaluate protection strategies for building reliable GMPLS networks. This is based on what we have called the network protection degree (NPD). The NPD consists of an a priori evaluation, the failure sensibility degree (FSD), which provides the failure probability, and an a posteriori evaluation, the failure impact degree (FID), which determines the impact on the network in case of failure, in terms of packet loss and recovery time. Having mathematical formulated these components, experimental results demonstrate the benefits of the utilization of the NPD, when used to enhance some current QoS routing algorithms in order to offer a certain degree of protection

Minimum interference routing with fast protection

One of the most effective techniques offering QoS routing is minimum interference routing. However, it is complex in terms of computation time and is not oriented toward improving the network protection level. In order to include better levels of protection, new minimum interference routing algorithms are necessary. Minimizing the failure recovery time is also a complex process involving different failure recovery phases. Some of these phases depend completely on correct routing selection, such as minimizing the failure notification time. The level of protection also involves other aspects, such as the amount of resources used. In this case shared backup techniques should be considered. Therefore, minimum interference techniques should also be modified in order to include sharing resources for protection in their objectives. These aspects are reviewed and analyzed in this article, and a new proposal combining minimum interference with fast protection using shared segment backups is introduced. Results show that our proposed method improves both minimization of the request rejection ratio and the percentage of bandwidth allocated to backup paths in networks with low and medium protection requirements

Resource dimensioning aspect of heterogeneous traffic with different service requirements: Integration versus segregation

In this paper, we consider the ATM networks in which the virtual path concept is implemented. The question of how to multiplex two or more diverse traffic classes while providing different quality of service requirements is a very complicated open problem. Two distinct options are available: integration and segregation. In an integration approach all the traffic from different connections are multiplexed onto one VP. This implies that the most restrictive QOS requirements must be applied to all services. Therefore, link utilization will be decreased because unnecessarily stringent QOS is provided to all connections. With the segregation approach the problem can be much simplified if different types of traffic are separated by assigning a VP with dedicated resources (buffers and links). Therefore, resources may not be efficiently utilized because no sharing of bandwidth can take place across the VP. The probability that the bandwidth required by the accepted connections exceeds the capacity of the link is evaluated with the probability of congestion (PC). Since the PC can be expressed as the CLP, we shall simply carry out bandwidth allocation using the PC. We first focus on the influence of some parameters (CLP, bit rate and burstiness) on the capacity required by a VP supporting a single traffic class using the new convolution approach. Numerical results are presented both to compare the required capacity and to observe which conditions under each approach are preferred

QoS online routing and MPLS multilevel protection: a survey

A survey of MPLS protection methods and their utilization in combination with online routing methods is presented in this article. Usually, fault management methods pre-establish backup paths to recover traffic after a failure. In addition, MPLS allows the creation of different backup types, and hence MPLS is a suitable method to support traffic-engineered networks. In this article, an introduction of several label switch path backup types and their pros and cons are pointed out. The creation of an LSP involves a routing phase, which should include QoS aspects. In a similar way, to achieve a reliable network the LSP backups must also be routed by a QoS routing method. When LSP creation requests arrive one by one (a dynamic network scenario), online routing methods are applied. The relationship between MPLS fault management and QoS online routing methods is unavoidable, in particular during the creation of LSP backups. Both aspects are discussed in this article. Several ideas on how these actual technologies could be applied together are presented and compared

Adding QoS protection in order to enhance MPLS QoS routing

In this paper, a method for enhancing current QoS routing methods by means of QoS protection is presented. In an MPLS network, the segments (links) to be protected are predefined and an LSP request involves, apart from establishing a working path, creating a specific type of backup path (local, reverse or global). Different QoS parameters, such as network load balancing, resource optimization and minimization of LSP request rejection should be considered. QoS protection is defined as a function of QoS parameters, such as packet loss, restoration time, and resource optimization. A framework to add QoS protection to many of the current QoS routing algorithms is introduced. A backup decision module to select the most suitable protection method is formulated and different case studies are analyzed

An improved method for discovering link criticality in transport networks

Quantitatively assessing the importance or criticality of each link in a network is of practical value to operators, as that can help them to increase the network's resilience, provide more efficient services, or improve some other aspect of the service. Betweenness is a graph-theoretical measure of centrality that can be applied to communication networks to evaluate link importance. However, as we illustrate in this paper, the basic definition of betweenness centrality produces inaccurate estimations as it does not take into account some aspects relevant to networking, such as the heterogeneity in link capacity or the difference between node-pairs in their contribution to the total traffic. A new algorithm for discovering link centrality in transport networks is proposed in this paper. It requires only static or semi-static network and topology attributes, and yet produces estimations of good accuracy, as verified through extensive simulations. Its potential value is demonstrated by an example application. In the example, the simple shortest-path routing algorithm is improved in such a way that it outperforms other more advanced algorithms in terms of blocking ratio