597 research outputs found

    Effective Performance Metrics for Multimedia Mission-critical Communication Systems

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    Creation of value with open source software in the telecommunications field

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    Tese de doutoramento. Engenharia Electrotécnica e de Computadores. Faculdade de Engenharia. Universidade do Porto. 200

    A Unified Mobility Management Architecture for Interworked Heterogeneous Mobile Networks

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    The buzzword of this decade has been convergence: the convergence of telecommunications, Internet, entertainment, and information technologies for the seamless provisioning of multimedia services across different network types. Thus the future Next Generation Mobile Network (NGMN) can be envisioned as a group of co-existing heterogeneous mobile data networking technologies sharing a common Internet Protocol (IP) based backbone. In such all-IP based heterogeneous networking environments, ongoing sessions from roaming users are subjected to frequent vertical handoffs across network boundaries. Therefore, ensuring uninterrupted service continuity during session handoffs requires successful mobility and session management mechanisms to be implemented in these participating access networks. Therefore, it is essential for a common interworking framework to be in place for ensuring seamless service continuity over dissimilar networks to enable a potential user to freely roam from one network to another. For the best of our knowledge, the need for a suitable unified mobility and session management framework for the NGMN has not been successfully addressed as yet. This can be seen as the primary motivation of this research. Therefore, the key objectives of this thesis can be stated as: To propose a mobility-aware novel architecture for interworking between heterogeneous mobile data networks To propose a framework for facilitating unified real-time session management (inclusive of session establishment and seamless session handoff) across these different networks. In order to achieve the above goals, an interworking architecture is designed by incorporating the IP Multimedia Subsystem (IMS) as the coupling mediator between dissipate mobile data networking technologies. Subsequently, two different mobility management frameworks are proposed and implemented over the initial interworking architectural design. The first mobility management framework is fully handled by the IMS at the Application Layer. This framework is primarily dependant on the IMS’s default session management protocol, which is the Session Initiation Protocol (SIP). The second framework is a combined method based on SIP and the Mobile IP (MIP) protocols, which is essentially operated at the Network Layer. An analytical model is derived for evaluating the proposed scheme for analyzing the network Quality of Service (QoS) metrics and measures involved in session mobility management for the proposed mobility management frameworks. More precisely, these analyzed QoS metrics include vertical handoff delay, transient packet loss, jitter, and signaling overhead/cost. The results of the QoS analysis indicates that a MIP-SIP based mobility management framework performs better than its predecessor, the Pure-SIP based mobility management method. Also, the analysis results indicate that the QoS performances for the investigated parameters are within acceptable levels for real-time VoIP conversations. An OPNET based simulation platform is also used for modeling the proposed mobility management frameworks. All simulated scenarios prove to be capable of performing successful VoIP session handoffs between dissimilar networks whilst maintaining acceptable QoS levels. Lastly, based on the findings, the contributions made by this thesis can be summarized as: The development of a novel framework for interworked heterogeneous mobile data networks in a NGMN environment. The final design conveniently enables 3G cellular technologies (such as the Universal Mobile Telecommunications Systems (UMTS) or Code Division Multiple Access 2000 (CDMA2000) type systems), Wireless Local Area Networking (WLAN) technologies, and Wireless Metropolitan Area Networking (WMAN) technologies (e.g., Broadband Wireless Access (BWA) systems such as WiMAX) to interwork under a common signaling platform. The introduction of a novel unified/centralized mobility and session management platform by exploiting the IMS as a universal coupling mediator for real-time session negotiation and management. This enables a roaming user to seamlessly handoff sessions between different heterogeneous networks. As secondary outcomes of this thesis, an analytical framework and an OPNET simulation framework are developed for analyzing vertical handoff performance. This OPNET simulation platform is suitable for commercial use

    Wireless triple play system

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    Dissertação para obtenção do Grau de Mestre em Engenharia Electrotécnica e ComputadoresTriple play is a service that combines three types of services: voice, data and multimedia over a single communication channel for a price that is less than the total price of the individual services. However there is no standard for provisioning the Triple play services, rather they are provisioned individually, since the requirements are quite different for each service. The digital revolution helped to create and deliver a high quality media solutions. One of the most demanding services is the Video on Demand (VoD). This implicates a dedicated streaming channel for each user in order to provide normal media player commands (as pause, fast forward). Most of the multimedia companies that develops personalized products does not always fulfil the users needs and are far from being cheap solutions. The goal of the project was to create a reliable and scalable triple play solution that works via Wireless Local Area Network (WLAN), fully capable of dealing with the existing state of the art multimedia technologies only resorting to open-source tools. This project was design to be a transparent web environment using only web technologies to maximize the potential of the services. HyperText Markup Language (HTML),Cascading Style Sheets (CSS) and JavaScript were the used technologies for the development of the applications. Both a administration and user interfaces were developed to fully manage all video contents and properly view it in a rich and appealing application, providing the proof of concept. The developed prototype was tested in a WLAN with up to four clients and the Quality of Service (QoS) and Quality of Experience (QoE) was measured for several combinations of active services. In the end it is possible to acknowledge that the developed prototype was capable of dealing with all the problems of WLAN technologies and successfully delivery all the proposed services with high QoE

    Mobile Networks

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    The growth in the use of mobile networks has come mainly with the third generation systems and voice traffic. With the current third generation and the arrival of the 4G, the number of mobile users in the world will exceed the number of landlines users. Audio and video streaming have had a significant increase, parallel to the requirements of bandwidth and quality of service demanded by those applications. Mobile networks require that the applications and protocols that have worked successfully in fixed networks can be used with the same level of quality in mobile scenarios. Until the third generation of mobile networks, the need to ensure reliable handovers was still an important issue. On the eve of a new generation of access networks (4G) and increased connectivity between networks of different characteristics commonly called hybrid (satellite, ad-hoc, sensors, wired, WIMAX, LAN, etc.), it is necessary to transfer mechanisms of mobility to future generations of networks. In order to achieve this, it is essential to carry out a comprehensive evaluation of the performance of current protocols and the diverse topologies to suit the new mobility conditions

    Investigation of an intelligent personalised service recommendation system in an IMS based cellular mobile network

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    Success or failure of future information and communication services in general and mobile communications in particular is greatly dependent on the level of personalisations they can offer. While the provision of anytime, anywhere, anyhow services has been the focus of wireless telecommunications in recent years, personalisation however has gained more and more attention as the unique selling point of mobile devices. Smart phones should be intelligent enough to match user’s unique needs and preferences to provide a truly personalised service tailored for the individual user. In the first part of this thesis, the importance and role of personalisation in future mobile networks is studied. This is followed, by an agent based futuristic user scenario that addresses the provision of rich data services independent of location. Scenario analysis identifies the requirements and challenges to be solved for the realisation of a personalised service. An architecture based on IP Multimedia Subsystem is proposed for mobility and to provide service continuity whilst roaming between two different access standards. Another aspect of personalisation, which is user preference modelling, is investigated in the context of service selection in a multi 3rd party service provider environment. A model is proposed for the automatic acquisition of user preferences to assist in service selection decision-making. User preferences are modelled based on a two-level Bayesian Metanetwork. Personal agents incorporating the proposed model provide answers to preference related queries such as cost, QoS and service provider reputation. This allows users to have their preferences considered automatically

    Extending AES with DH Key-Exchange to Enhance VoIP Encryption in Mobile Networks

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    Recently,the evolution and progress have become significant in the field of information technology and mobile technology, especially inSmartphone applications that are currently widely spreading. Due to the huge developments in mobile and smartphone technologies in recent years, more attention is given to voice data transmission such as VoIP (Voice overIP) technologies– e.g. (WhatsApp, Skype, and Face Book Messenger). When using VoIP services over smartphones, there are always security and privacy concerns like the eavesdropping of calls between the communicating parties. Therefore, there is a pressing need to address these risks by enhancing the security level and encryption methods. In this work, we use scheme to encrypt VoIP channels using (128, 192 & 256-bit) enhanced encryption based on the Advanced Encryption Standard (AES) algorithm, by extending it with the well-known Diffie-Hellman (DH) key exchange method. We have performed a series of real tests on the enhanced (AES-DH) algorithm and compared its performance with the generic AES algorithm. The results have shown that we can get a significant increase in the encryption strength at a very small overhead between 4% and 7% of execution timebetween AES and AEScombine withDH for all scenario which was incurred by added time of encryption and decryption. Our approach uses high security and speed and reduces the voice delay.In dealing with sound transfer process via the internet, we use the SIP server to authenticate the communication process between the two parties. The implementation is done on a mobile device (Which is operated by (Android) system) because it has recently been widely used among different people around the world.اصبحت الثورة والتطور كبيرة حديثاً في حقول تكنولوجيا االتصاالت واليواتف النقالة، وخصوصا في تطبيقات اليواتف الذكية التي تنتشر حاليا بشكل واسع. وتم اعطاء المزيد من االىتمام لنقل البيانات الصوتية مثل تكنولوجيا االتصال عبر بروتكول االنترنت، عمى سبيل المثال: )الواتساب، السكايب، الفيس بوك، والماسنجر(. ويعزى ذلك لمتطور الكبير في تكنولوجيا اليواتف النقالة والذكية في السنوات االخيرة. عند استخدام خدمات االتصال عبر بروتكول االنترنت VoIP ،ىناك مخاوف دائمة حول الحماية والخصوصية كالتجسس عمى المكالمات بين جيات االتصال. ولذلك ىنالك حاجة ماسة لمعالجة ىذه المخاطر عن طريق تحسين مستوى الحماية وطرق التشفير. في ىذا العمل، نستخدم/ نجمع بين اثنتين من الخوارزميات لتشفير قنوات االتصال عبر بروتوكول االنترنت )128 ، 192 ،و 256 بت( عبر خوارزمية AESوتمديدىا عبر طريقة تبادل ديفي ىيممان الرئيسية المعروفة. وقمنا باداء العديد من التجارب الحقيقية عمى DH-AES ، وقمنا بمقارنة ادائيا مع اداء خوارزمية معيار التشفير المتقدم العامة. اظيرت النتائج انو بامكاننا الحصول عمى زيادة كبيرة في قوة التشفير بنسبة صغيرة جدا بين 4 %و7 %من وقت التنفيذ بين AESو DH/AES لجميع السيناريو والتي تم تكبدىا من قبل الوقت المضاف لمتشفير وفك التشفير. يستخدم نيجنا درجة عالية من الحماية والسرعة ويقمل من تأخير الصوت، ونستخدم في التعامل مع عممية نقل الصوت عبر االنترنت Server SIPلتوثيق عممية االتصال بين الجيتين. وتم التنفيذ عمى ىاتف نقال يعمل عمى نظام اندرويد؛ النو استخدم بشكل واسع مؤخرا بين مختمف الناس حول العالم
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