Homomorphic encryption (HE) enables computations on encrypted data making it possible to perform calculations on a server without sharing the secret key for decryption. HE is relatively new and has seen significant improvements in recent years in terms of speed of encryption, decryption, operations, and the number of operations possible to perform in a row without damaging the ciphertext. These improvements open up new possibilities, such as using HE in voice over IP (VoIP) and still being able to mix audio streams at the server without decrypting them, creating a scalable and secure application.  This thesis evaluates the performance of three HE schemes, BGV, BFV, and CKKS, implemented by the open-source library Palisade and compares their performance to a non-HE scheme AES in terms of encryption time, decryption time and end-to-end latency. Furthermore, the performance of mixing with HE-encrypted audio files is evaluated. The work is a proof-of-concept that allows the user to send audio files of different sample rates and batch sizes to compare the performance. It also investigates the Quality of Experience by measuring the audio quality after the mixing, using PESQ and POLQA. The results show that BGV performs almost as good as AES for higher batch sizes, while BFV performs almost as good in most cases and trails behind in others. CKKS, on the other hand, is the slowest scheme but is still fast enough in some cases to be considered a possible encryption scheme. Furthermore, the tests show that the HE schemes do not decrease the listening quality much according to PESQ and POLQA, as all tests concluded a result that is considered good or excellent. The number of files being mixed had a negative impact on narrowband and wideband audio streams, while it did not affect superwideband and fullband.

No description available.

All Mobile Network Operators (MNOs) as well as international carriers are moving voice services from the legacy Public Switched Telephone Network (PSTN) to Voice over IP (VoIP). The benefit is that VoIP traffic can be easily rerouted at any moment, thus giving companies a variety of options as traffic can be rerouted to any carrier of choice leading to different Quality of Service (QoS) levels (and thus agreements) as well as different prices to choose from. With a fierce competition for the telecom companies involved in the voice traffic hubbing business, this new landscape offers not only opportunities but also opens the system to vulnerabilities. The stakes are actually quite high: If harm can be done to one of these international carriers, other companies will route away their traffic. The result will be significant financial damages for the company as well as a serious harm to its reputation. The aim of this paper is to raise awareness that internationalcarriers and in particular their VoIP traffic can be exposed to debilitating attacks to harm these systems that are critical for our everyday life. The experimentation in this project demonstrates with a hands-on example how a major carrier can be hacked and rendered useless. In particular, we craft a framework for testing the security of interconnects between MNOs and international carriers. The central point of the paper will be to demonstrate how easy it can be to attack major carriers in the market: using common open source tools without having any information in advance. Moreover, the goal is to understand how the market functions, how interconnects between companies are built, where the weaknesses are, and which solutions can thwart those threats and secure these systems.

This thesis proposes a design of a rapidly deployable cellular network prototype that provides voice and data communications and it is interoperable with legacy devices and the existing network infrastructure. The prototype is based on software defined radio and makes use of IEEE 802.11 unlicensed wireless radio frequency (RF) band for backhaul link and an open source GSM implementation software. The prototype is also evaluated in environments where there is limited control of the radio frequency landscape, and using Voice Over Internet Protocol (VoIP) performance metrics to measure the quality of service. It is observed that in environments where the IEEE 802.11 band is not heavily utilized, a large number of calls are supported with good quality of service. However, when this band is heavily utilized only a few calls can be supported as the quality of service rapidly degrades with increasing number of calls, which is due to interference. It is concluded that in order to achieve tolerable voice quality, unused licensed spectrum is needed for backhaul communication between base stations.

Les réseaux maillés sans fil (RMSF), grâce à leurs caractéristiques avantageuses, sont considérés comme une solution efficace pour le support des services de voix, vidéo et de données dans les réseaux de prochaine génération. Le standard IEEE 802.16-d a spécifié pour les RMSF, à travers son mode maillé, deux mécanismes de planifications de transmission de données; à savoir la planification centralisée et la planification distribuée. Dans ce travail, on a évalué le support de la qualité de service (QdS) du standard en se focalisant sur la planification distribuée. Les problèmes du système dans le support du trafic de voix ont été identifiés. Pour résoudre ces problèmes, on a proposé un protocole pour le support de VoIP (AVSP) en tant qu’extension au standard original pour permettre le support de QdS au VoIP. Nos résultats préliminaires de simulation montrent qu’AVSP offre une bonne amélioration au support de VoIP. / Wireless mesh networks (WMNs), because of their advantageous characteristics, are considered as an effective solution to support voice services, video and data in next generation networks. The IEEE 802.16-d specified for WMNs, through its mesh mode, two mechanisms of scheduling data transmissions; namely centralized scheduling and distributed scheduling. In this work, we evaluated the support of the quality of service (QoS) of the standard by focusing on distributed scheduling. System problems in the support of voice traffic have been identified. To solve these problems, we proposed a protocol for supporting VoIP, called Assisted VoIP Scheduling Protocol (AVSP), as an extension to the original standard to support high QoS to VoIP. Our preliminary simulation results show that AVSP provides a good improvement to support VoIP.

Made available in DSpace on 2016-04-04T18:31:27Z (GMT). No. of bitstreams: 1 Eduardo Pinto de Oliveira.pdf: 2067309 bytes, checksum: 3dc805f0ad9724f8d04d0359795ed071 (MD5) Previous issue date: 2009-02-13 / The objective of this work is to present the metrics of performance evaluation in Broadband Wireless Access (BWA). To achieve this goal it was necessary to build a Framework of network management customized to the equipment used. It was applied the knowledge in signals propagation of radio frequency (RF), radio planning of cellular systems, network management and statistical analyses. In the realization of the tests for the data collect it was configured a setup of tests with one Radio Base Station (BTS) and two Remote Stations (RS) located in the Pontif?cia Universidade Cat?lica de Campinas (PUC Campinas). It was used a technology commercially named as Pre-Wireless Interoperability of Multiple Accesses (Pre-WiMAX), operating in 5.8 GHz. This technology uses Orthogonal Frequency Division Multiplexing (OFDM) as multiplex technique and Carrier Sense Multiple Access (CSMA) as an access control to the media. In the development, it is presented a set of metrics related to the signals propagation by RF. The data collect was executed using the Simple Network Management Protocol (SNMP). The performance evaluation has considered the measures realized and its analytic and statistic treatments for a long time. By using the results of the measures, it was built the metrics that allow the evaluation of the performance in this network type, such as: link efficiency, throughput, bit error rate (BER), frame error rate (FER) and packet error rate (PER), among others. The work, as a whole, presents a strategy of practical evaluation applicable to BWA networks, creating indicators for decision-makings. To validate and complement the work it was done an Quality of Service (QoS) evaluation according to the International Telecommunication Union - Telecommunication sector (ITU-T) and the International Engineering Task Force (IETF) comparing the results with and without prioritization of Voice over Internet Protocol (VoIP) service . / O objetivo deste trabalho ? apresentar m?tricas de avalia??o de desempenho em Broadband Wireless Networks (BWA). Para atingir este objetivo foi necess?ria a constru??o de um Framework de ger?ncia de redes customizado aos equipamentos utilizados. Foram aplicados os conhecimentos de propaga??o de sinais de r?dio freq??ncia (RF), planejamento de sistemas celulares, gerenciamento de redes e an?lise estat?stica. Na realiza??o dos testes para a coleta de dados foi configurado um setup de testes com uma Esta??o R?dio Base (ERB) e duas Esta??es Remotas (ER), localizadas na Pontif?cia Universidade Cat?lica de Campinas (PUC Campinas). Para a valida??o da metodologia foi utilizada uma tecnologia denominada comercialmente como Pre-Wireless Interoperability of Multiple Accesses (Pre-WiMAX), operando em 5.8 GHz. Esta tecnologia utiliza Orthogonal Frequency Division Multiplexing (OFDM) como t?cnica de multiplexa??o e Carrier Sense Multiple Access (CSMA) como controle de acesso ao meio. No desenvolvimento ? apresentado um conjunto de m?tricas, referentes ? propaga??o de sinais por RF. A coleta de dados foi efetuada utilizando Simple Network Management Protocol (SNMP). A avalia??o de desempenho considerou as medidas realizadas e o seu tratamento anal?tico e estat?stico por longos per?odos de tempo. Com a utiliza??o dos resultados de medidas, foram constru?das as m?tricas que permitem avaliar o desempenho deste tipo de rede, tais como: efici?ncia de link, throughput, bit error rate (BER), frame error rate (FER), packet error rate (PER), entre outras. O trabalho como um todo apresenta uma estrat?gia de avalia??o pr?tica e aplic?vel a redes BWA, criando indicadores para tomadas de decis?o. Para validar e complementar o trabalho foi efetuada uma avalia??o de Quality of Service (QoS) segundo a International Telecommunication Union Telecommunication sector (ITU-T) e a International Engineering Task Force (IETF) com a compara??o de resultados sem e com prioriza??o do servi?o Voice over Internet Protocol (VoIP).

No description available.

Les réseaux maillés sans fil (RMSF), grâce à leurs caractéristiques avantageuses, sont considérés comme une solution efficace pour le support des services de voix, vidéo et de données dans les réseaux de prochaine génération. Le standard IEEE 802.16-d a spécifié pour les RMSF, à travers son mode maillé, deux mécanismes de planifications de transmission de données; à savoir la planification centralisée et la planification distribuée. Dans ce travail, on a évalué le support de la qualité de service (QdS) du standard en se focalisant sur la planification distribuée. Les problèmes du système dans le support du trafic de voix ont été identifiés. Pour résoudre ces problèmes, on a proposé un protocole pour le support de VoIP (AVSP) en tant qu’extension au standard original pour permettre le support de QdS au VoIP. Nos résultats préliminaires de simulation montrent qu’AVSP offre une bonne amélioration au support de VoIP. / Wireless mesh networks (WMNs), because of their advantageous characteristics, are considered as an effective solution to support voice services, video and data in next generation networks. The IEEE 802.16-d specified for WMNs, through its mesh mode, two mechanisms of scheduling data transmissions; namely centralized scheduling and distributed scheduling. In this work, we evaluated the support of the quality of service (QoS) of the standard by focusing on distributed scheduling. System problems in the support of voice traffic have been identified. To solve these problems, we proposed a protocol for supporting VoIP, called Assisted VoIP Scheduling Protocol (AVSP), as an extension to the original standard to support high QoS to VoIP. Our preliminary simulation results show that AVSP provides a good improvement to support VoIP.

This work deals with the wireless Wi-Fi networks, that used unlicenced ISM frequency band 2,4 GHz. These wireless networks are very extended in these days and used mainly for the Internet connection. With the multimedia data transfers expanding it’s necessary to ensure the specific quality of service QoS in wireless networks mainly for applications, which are sensitive to delay or packets lost. The main aim of this work is to describe Wi-Fi networks based on IEEE 802.11b/g/n standards, description of QoS techniques according to IEEE 802.11e standard and description of parameters describing QoS for the VoIP services. The practical part is divided on a two parts. The problems of measuring the radio link quality and the creation of simple program for quality of wireless connection analysis are solved in the first part. The second part incluledes measuring of the lost packets number in Wi-Fi network with the commercial application AirMagnet Laptop Wireless LAN Analyzer and measuring of the signal noise influence with the help of spectrum analyzer and vector signal generator.

A hi-tech company often focuses on being innovative by providing product offerings as product leader, fast follower or with operational excellence. In the international calling sector the technological solutions are numerous. The providers are, for instance, normal telecom providers, Voice over Internet Protocol (VoIP) and Mobile virtual network operators (MVNO). This means that a company faces not only the competitors that offer the same solution but also from outside the company’s business sector. The company thus needs to tackle many challenges, such as fast-paced product development, market expansion, competitor volatility, at the same time as the company cultivates its brand assets. This study focuses on the branding strategy within the VoIP telecom sector. It aims to set a guideline for how companies, in particular in the VoIP telecom sectors, cultivate and enhance their brand identity in order to differentiate themselves from competitors as well as achieve a successful and sustainable level of brand equity. The thesis also studies the brand strategies that have already manifested themselves within the providers of international calling services, in particular VoIP providers and a couple of MVNO providers. By conducting the brand identity and brand equity analysis, customer analysis and competitors’ analysis, a company can make a decision on brand strategy that will further associate, differentiate, energize and support its brands. The research framework consists of both the corporate and consumer perspectives. It consists of brand theory, market research, competitor analysis and the company’s brand identity, as well as brand awareness analysis. The thesis presents the Swedish VoIP consumers’ behavior and trends, the guideline and case study on how a company bridges the gap between brand identity and brand equity as well as the guideline and case study of brand portfolio strategies that have been explored within the VoIP telecom sectors, i.e. VoIP branding.