Today, an increasing amount of the functionality traditionally associated with stationary computers is moving into mobile devices. Furthermore, the number of applications that retrieve data via networks is increasing in view of the recent growth of video streaming to the browsers, further emphasizing the Quality of Experience (QoE) requirements of mobile users today. Obviously, QoE demands are not necessarily connected to the fact that the link is mobile, which puts significant QoS demands onto the mobile systems involved. Consequently, this requires mobile systems to be flexible and adaptable to meet the QoS demands and cope with dynamic operating environments. Additionally, the rapid migration towards wireless connectivity and the abundance of mobile devices has put even greater strain on current wireless access technology designs. The frequency spectrum is a limited resource and must be efficiently utilized to conserve capacity and avoid overcrowding, particularly in densely populated areas. Hence, new wireless technologies and innovative architectural designs are needed to manage and to govern the wireless domain. The thesis is about combining the potential of Dynamic Spectrum Access (DSA) provided by Cognitive Radio (CR) with the scalability and fault tolerance capabilities demonstrated by Peer-to-Peer (P2P) systems. By combining these two technologies, we show that we can improve the resource utilization in crowded metropolitan areas to ensure service continuation between local mobile devices with minimal infrastructure requirements. The aim is to optimize the communication between Cognitive Radio Devices (CRD) in a Cognitive Radio Network (CRN) according to end-to-end (e2e) goals and user preferences.

There is no doubt that security mechanisms, such as authentication, are required in Information and Communication Technology, but they come at a price: Users need to spend additional time and effort to authenticate themselves. With this in mind, user perception of authentication is an important factor for successful use of authentication solutions. If users perceive an authentication procedure as time-consuming and difficult, they might ignore or try to bypass it. Therefore, user-perceived Quality of Experience (QoE) should be investigated. QoE is a challenging area as it, in this case, covers network performance and security as well as Human Computer Interaction and user experience. Throughout this work, authentication performance is investigated, starting with a framework for evaluating security architectures and authentication solutions in general. Criteria for user-friendliness, security and simplicity are described and the evaluation methods span from theoretical to practical, and qualitative to quantitative methods. The latter two aspects are investigated by a study of user experience of web authentication with OpenID using the EAP-SIM authentication method. The user experiments resulted in several user models of QoE. One particular user model for QoE, the exponential relationship between QoE and network level performance, was then used in further experiments on performance evaluation of OpenID authentication using EAP-SIM. The latter was done to determine the decisive factors for QoE of the authentication method in use. The results from these experiments show that the combination of OpenID and EAP-SIM for authentication over a secure tunnel is not appropriate to use over networks with high delays. The latter implies the need for improvements of the authentication procedure of OpenID using EAP-SIM, which should be addressed in the future. The user model of QoE obtained in this study will even help to quantify the performance aspects of future authentication procedures.

To an end user, Quality of Experience (QoE) matters more than Quality of Service (QoS) because she is the owner of her experience, which is the result of her perception. In recent times, QoE got increasingly much attention from service providers, operators, manufacturers and researchers. Amongst others, they are interested to know how the users perceive the quality of multimedia streaming and how to predict the QoE by measuring network performance parameters. Below the network layer, different access networks can be used, but the internet and transport layers remain the same for everyone on best-effort internet. We highlight a set of possible factors that are contributing towards the QoE, from network via transport to application layer, including applications, codecs, middleware and devices. To investigate the relationship of QoS and QoE, emulation-based experiments were designed. For the purpose of emulation, different shapers are in use by the research community. We selected three popular shapers, NetEm, NISTnet and KauNet, and investigated their emulation capabilities with focus on delay, delay variation and bit rate in order to be able to select the best-suited shaper for future use. Then, we studied the effect of QoS parameters on mobile video QoE. To evaluate the video QoE, user tests were conducted. We observe a much larger sensitivity of users to freezes and their placement within the video than what is predicted by an objective video quality assessment tool that is recommended by the standardisation organization ITU. Furthermore, we investigated the role of codec and device on QoE in view of network-induced problems.

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It was known for a long time that OpenStack has issues with scalability. Peer-to-Peer systems, on the other hand, have proven to scale well without significant reduction of performance. The objectives of this thesis are to study the challenges associated with P2P-enhanced clouds and present solutions for overcoming them. As a case study, we take the architecture of the P2P-enhanced OpenStack implemented at Ericsson that uses the CYCLON P2Pprotocol. We study the OpenStack architecture and P2P technologies and finally propose solutions and provide possibilities in addressing the challenges that are faced by P2P-enhanced OpenStack clouds. We emphasize mainly on a decentralized identity service and management of Virtual machine images. This work also investigates the characterization of P2P architectures for their use in P2P-enhanced OpenStack clouds. The results section shows that the proposed solution enables the existing P2P system to scale beyond what was originally possible. We also show that the P2P-enhanced system performs better than the standard OpenStack. / <p>Ericsson Cloud Research supported this work through the guidance of Dr. Fetahi Wuhib, Dr. Joao Monteiro Soares and Vinay Yadav, Experienced Researchers, Ericsson Cloud Research, Kista, Stockholm.</p>

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The purpose of this thesis is going to design a microstrip antenna that can detect the different tissue, according to this clue, we suppose that it can be used in medical application, for example to detect the breast tumor. Our research and guess are based on the different electrical properties of the tissue. Follow the conductivity and permittivity of different tissue, a simple 3D breast structure is going to be modelled, and a tumor tissue will be defined too. Four types of antenna have been designed and simulated in HFSS. The antenna with best performance will be manufactured, which is the rectangular microstrip antenna with gap, it works under 2.45Ghz resonate frequency, and with dimension 37.26mm×28.83mm. Test S21 of antenna in Vector Network Analyser with different biological tissue, in order to make a simple prove that the antenna can detect the different tissue. The result shows when we use the different tissue’s size and quantity, the S21 changes.

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