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  • 201.
    venkesh, kandari
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Implementation and Performance Optimization of WebRTC Based Remote Collaboration System2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 202.
    Virinchi, Billa
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Data Visualization of Telenor mobility data2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Nowadays with the rapid development of cities, understanding the human mobility patterns of subscribers is crucial for urban planning and for network infrastructure deployment. Today mobile phones are electronic devices used for analyzing the mobility patterns of the subscribers in the network, because humans in their daily activities they carry mobile phones for communication purpose. For effective utilization of network infrastructure (NI) there is a need to study on mobility patterns of subscribers.

     

    The aim of the thesis is to simulate the geospatial Telenor mobility data (i.e. three different subscriber categorized segments) and provide a visual support in google maps using google maps API, which helps in decision making to the telecommunication operators for effective utilization of network infrastructure (NI).

     

     In this thesis there are two major objectives. Firstly, categorize the given geospatial telenor mobility data using subscriber mobility algorithm. Secondly, providing a visual support for the obtained categorized geospatial telenor mobility data in google maps using a geovisualization simulation tool.

     

     The algorithm used to categorize the given geospatial telenor mobility data is subscriber mobility algorithm. Where this subscriber mobility algorithm categorizes the subscribers into three different segments (i.e. infrastructure stressing, medium, friendly). For validation and confirmation purpose of subscriber mobility algorithm a tetris optimization model is used. To give visual support for each categorized segments a simulation tool is developed and it displays the visualization results in google maps using Google Maps API.

     

    The result of this thesis are presented to the above formulated objectives. By using subscriber mobility algorithm and tetris optimization model to a geospatial data set of 33,045 subscribers only 1400 subscribers are found as infrastructure stressing subscribers. To look informative, a small region (i.e. boras region) is taken to visualize the subscribers from each of the categorized segments (i.e. infrastructure stressing, medium, friendly).

     

     The conclusion of the thesis is that the functionality thus developed contributes to knowledge discovery from geospatial data and provides visual support for decision making to telecommunication operators.

    Nowadays with the rapid development of cities, understanding the human mobility patterns of subscribers is crucial for urban planning and for network infrastructure deployment. Today mobile phones are electronic devices used for analyzing the mobility patterns of the subscribers in the network, because humans in their daily activities they carry mobile phones for communication purpose. For effective utilization of network infrastructure (NI) there is a need to study on mobility patterns of subscribers.

     

    The aim of the thesis is to simulate the geospatial Telenor mobility data (i.e. three different subscriber categorized segments) and provide a visual support in google maps using google maps API, which helps in decision making to the telecommunication operators for effective utilization of network infrastructure (NI).

     

     In this thesis there are two major objectives. Firstly, categorize the given geospatial telenor mobility data using subscriber mobility algorithm. Secondly, providing a visual support for the obtained categorized geospatial telenor mobility data in google maps using a geovisualization simulation tool.

     

     The algorithm used to categorize the given geospatial telenor mobility data is subscriber mobility algorithm. Where this subscriber mobility algorithm categorizes the subscribers into three different segments (i.e. infrastructure stressing, medium, friendly). For validation and confirmation purpose of subscriber mobility algorithm a tetris optimization model is used. To give visual support for each categorized segments a simulation tool is developed and it displays the visualization results in google maps using Google Maps API.

     

    The result of this thesis are presented to the above formulated objectives. By using subscriber mobility algorithm and tetris optimization model to a geospatial data set of 33,045 subscribers only 1400 subscribers are found as infrastructure stressing subscribers. To look informative, a small region (i.e. boras region) is taken to visualize the subscribers from each of the categorized segments (i.e. infrastructure stressing, medium, friendly).

     

     The conclusion of the thesis is that the functionality thus developed contributes to knowledge discovery from geospatial data and provides visual support for decision making to telecommunication operators.

  • 203.
    Vishnubhotla Venkata Krishna, Sai Datta
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Cost Aware Virtual Content Delivery Network for Streaming Multimedia: Cloud Based Design and Performance Analysis2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Significant portion of today’s internet traffic emerge from multimedia services. When coupled with growth in number of users accessing these services, there is tremendous increase in network traffic. CDNs aid in handling this traffic and offer reliable services by distributing content across different locations. The concept of virtualization transformed traditional data centers into flexible cloud infrastructure. With the advent of cloud computing technology, multimedia providers have scope for establishing CDN using network operator’s cloud environment. However, the main challenge while establishing such CDN is implementing a cost efficient and dynamic mechanism which guarantees good service quality to users.

    This thesis aims to develop, implement and assess the performance of a model that coordinates deployment of virtual servers in the cloud. A solution which dynamically spawns and releases virtual servers according to variations in user demand has been proposed. Cost-based heuristic algorithm is presented for deciding the placement of virtual servers in OpenStack based federated clouds. Further, the proposed model is implemented on XIFI cloud and its performance is measured. Results of the performance study indicate that virtual CDNs offer reliable and prompt services. With virtual CDNs, multimedia providers can regulate expenses and have greater level of flexibility for customizing the virtual servers deployed at different locations.

  • 204. Vo, Nguyen-Son
    et al.
    Duong, Trung Quong
    Zepernick, Hans-Jürgen
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Fiedler, Markus
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    A Cross-Layer Optimized Scheme and Its Application in Mobile Multimedia Networks With QoS Provision2016In: IEEE Systems Journal, ISSN 1932-8184, E-ISSN 1937-9234, Vol. 10, no 2, p. 817-830Article in journal (Refereed)
    Abstract [en]

    To cope with the rapid growth of multimedia applications that requires dynamic levels of quality of service (QoS), cross-layer (CL) design, where multiple protocol layers are jointly combined, has been considered to provide diverse QoS provisions for mobile multimedia networks. However, there is a lack of a general mathematical framework to model such CL scheme in wireless networks with different types of multimedia classes. In this paper, to overcome this shortcoming, we therefore propose a novel CL design for integrated real-time/non-real-time traffic with strict preemptive priority via a finite-state Markov chain. The main strategy of the CL scheme is to design a Markov model by explicitly including adaptive modulation and coding at the physical layer, queuing at the data link layer, and the bursty nature of multimedia traffic classes at the application layer. Utilizing this Markov model, several important performance metrics in terms of packet loss rate, delay, and throughput are examined. In addition, our proposed framework is exploited in various multimedia applications, for example, the end-to-end real-time video streaming and CL optimization, which require the priority-based QoS adaptation for different applications. More importantly, the CL framework reveals important guidelines as to optimize the network performance.

  • 205.
    Vyshnavi, Bandaru
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Virtual VPN in the Cloud: Design and Modelling of an IPSec VPN in Virtualized Environment.2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 206.
    Wen, Wei
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Khatibi, Siamak
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    A New Methodology for Evaluating Various Methods of 3D Reconstruction from Single Image2012In: Image and Signal Processing (CISP), 2012 5th International Congress on, IEEE, 2012, p. 582-586Conference paper (Refereed)
    Abstract [en]

    Consumer market is recently experiencing 3D display. To prepare the market for new era of 3D TV, the 3D display popularity can be increased by making ease of capturing or generating of stereo information. The results of recent research on 3D structure modeling from single images can be used to generate stereo images. We evaluate some of typical 3D reconstruction methods from single images in relation of using the results in 3D display. The evaluation is not only based on the experts' opinions and statistic test but also an objective methodology is introduced. Only planar surfaces, like as in any man made structure scenes, are used in the objective evaluation. The number of planes is varied in a controlled way. Three popular and classic methods are chosen for the evaluation with this new methodology. And the evaluation result is consistent with the statistical result of human inquiries.

  • 207.
    Wen, Wei
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Khatibi, Siamak
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    A Software Method to Extend Tonal Levels and Widen Tonal Range of CCD Sensor Images2015In: 2015 9TH INTERNATIONAL CONFERENCE ON SIGNAL PROCESSING AND COMMUNICATION SYSTEMS (ICSPCS), IEEE Communications Society, 2015Conference paper (Refereed)
    Abstract [en]

    As one of important outcomes of the past decades of researches on sensor arrays for digital cameras, the manufacturers of sensor array technology have responded to the necessity and importance of obtaining an optimal fill factor, which has great impact on collection of incident photons on the sensor, with hardware solution e.g. by introducing microlenses. However it is still impossible to make a fill factor of 100% due to the physical limitations in practical development and manufacturing of digital camera. This has been a bottle neck problem for improving dynamic range and tonal levels for digital cameras e.g. CCD cameras. In this paper we propose a software method to not only widen the recordable dynamic range of a captured image by a CCD camera but also extend its tonal levels. In the method we estimate the fill factor and by a resampling process a virtual fill factor of 100% is achieved where a CCD image is rearranged to a new grid of virtual subpixels. A statistical framework including local learning model and Bayesian inference is used for estimating new sub-pixel intensity values. The highest probability of sub-pixels intensity values in each resampled pixel area is used to estimate the pixel intensity values of the new image. The results show that in comparison to the methods of histogram equalization and image contrast enhancement, which are generally used for improving the displayable dynamic range on only one image, the tonal levels and dynamic range of the image is extended and widen significantly and respectively.

  • 208.
    Wen, Wei
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Khatibi, Siamak
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Back to basics: Towards novel computation and arrangement of spatial sensory in images2016In: Acta Polytechnica, ISSN 1210-2709, Vol. 56, no 5, p. 409-416Article in journal (Refereed)
    Abstract [en]

    The current camera has made a huge progress in the sensor resolution and the low-luminance performance. However, we are still far from having an optimal camera as powerful as our eye is. The study of the evolution process of our visual system indicates attention to two major issues: the form and the density of the sensor. High contrast and optimal sampling properties of our visual spatial arrangement are related directly to the densely hexagonal form. In this paper, we propose a novel software-based method to create images on a compact dense hexagonal grid, derived from a simulated square sensor array by a virtual increase of the fill factor and a half a pixel shifting. After that, the orbit functions are proposed for a hexagonal image processing. The results show it is possible to achieve image processing operations in the orbit domain and the generated hexagonal images are superior, in detection of curvature edges, to the square images. We believe that the orbit domain image processing has a great potential to be the standard processing for hexagonal images.

  • 209.
    Wen, Wei
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Khatibi, Siamak
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Novel Software-based Method to Widen Dynamic Range of CCD Sensor Images2015In: / [ed] Yu-Jin Zhang, Springer, 2015, Vol. 9218, p. 572-583Conference paper (Refereed)
    Abstract [en]

    In the past twenty years, CCD sensor has made huge progress in improving resolution and low-light performance by hardware. However due to physical limits of the sensor design and fabrication, fill factor has become the bottle neck for improving quantum efficiency of CCD sensor to widen dynamic range of images. In this paper we propose a novel software-based method to widen dynamic range, by virtual increase of fill factor achieved by a resampling process. The CCD images are rearranged to a new grid of virtual pixels com-posed by subpixels. A statistical framework consisting of local learning model and Bayesian inference is used to estimate new subpixel intensity. By knowing the different fill factors, CCD images were obtained. Then new resampled images were computed, and compared to the respective CCD and optical image. The results show that the proposed method is possible to widen significantly the recordable dynamic range of CCD images and increase fill factor to 100 % virtually.

  • 210.
    Wen, Wei
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Khatibi, Siamak
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Towards Measuring of Depth Perception from Monocular Shadow Technique with Application in a Classical Painting2016In: Journal of Computers, ISSN 1796-203X, Vol. 11, p. 310-319Article in journal (Refereed)
    Abstract [en]

    Depth perception is one of important abilities of the human visual system to perceive the three dimensional world. Shadow technique that offers different depth information from different viewing points, known as Da Vinci stereopsis, has been used in classical paintings. In this paper, we report a method towards measuring the relative depth information stimulated by Da Vinci stereopsis in a classical painting. We set up a positioning array of cameras for capturing images from the portrait using a high resolution camera, where the changes of shadow areas are measured by featuring the effects as point and line changes. The result shows that 3D effects of the classical painting are not only a perceptual phenomenon but they are also physically tangible and can be measured. We confirm validity of the method by its implementation even on a typical single image and comparison of results between the single image and the portrait.

  • 211.
    Yao, Yong
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    A Software Framework for Prioritized Spectrum Access in Heterogeneous Cognitive Radio Networks2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Today, the radio spectrum is rarely fully utilized. This problem is valid in more domains, e.g., time, frequency and geographical location. To provide an efficient utilization of the radio spectrum, the Cognitive Radio Networks (CRNs) have been advanced. The key idea is to open up the licensed spectrum to unlicensed users, thus allowing them to use the so-called spectrum opportunities as long as they do not harmfully interfere with licensed users. An important focus is laid on the limitation of previously reported research efforts, which is due to the limited consideration of the problem of competition among unlicensed users for spectrum access in heterogeneous CRNs. A software framework is introduced, which is called PRioritized Opportunistic spectrum Access System (PROAS). In PROAS, the heterogeneity aspects of CRNs are specifically expressed in terms of cross-layer design and various wireless technologies. By considering factors like ease of implementation and efficiency of control, PROAS provides priority scheduling based solutions to alleviate the competition problem of unlicensed users in heterogenous CRNs. The advanced solutions include theoretical models, numerical analysis and experimental simulations for performance evaluation. By using PROAS, three particular CRN models are studied, which are based on ad-hoc, mesh-network and cellular-network technologies. The reported results show that PROAS has the ability to bridge the gap between research results and the practical implementation of CRNs.

  • 212.
    Yao, Yong
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Popescu, Adrian
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    On Energy Consumption in Mobile Multimedia Networks with OpenFlow Switch2016In: 2016 INTERNATIONAL CONFERENCE ON COMMUNICATIONS (COMM 2016), IEEE, 2016, p. 309-312Conference paper (Refereed)
    Abstract [en]

    In mobile multimedia networks, the video flow usually operates in an end-to-end manner from Head-End to mobile terminals. However, measuring the energy consumption associated with a video flow is a sophisticated process due to the complexity related to this. In the paper, a theoretical measurement approach is suggested to estimate the energy consumption of a video flow through mobile multimedia networks enhanced with the support of OpenFlow switch. Two different power models are built up to compute the traffic related energy consumption at the network element side. The numerical derivation of these two theoretical models is presented.

  • 213.
    Yao, Yong
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Popescu, Alexandru
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Popescu, Adrian
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    On Fuzzy Logic-Based Channel Selection in Cognitive Radio Networks2014In: Software-Defined and Cognitive Radio Technologies for Dynamic Spectrum Management / [ed] Kaabouch, Naima; Hu, Wen-Chen, Hershey, PA 17033, USA: IGI-Global , 2014Chapter in book (Refereed)
    Abstract [en]

    Cognitive radio networks are a new technology based on which unlicensed users are allowed access to licensed spectrum under the condition that the interference perceived by licensed users is minimal. That means unlicensed users need to learn from environmental changes and to take appropriate decisions regarding the access to the radio channel. This is a process that can be done by unlicensed users in a cooperative or non-cooperative way. Whereas the non-cooperative algorithms are risky with regard to performance, the cooperative algorithms have the capability to provide better performance. Our paper reports therefore a new fuzzy logic based decision making algorithm for channel selection. The underlying decision criterion considers statistics of licensed users channel occupancy as well as information about the competition level of unlicensed users. Our theoretical studies indicate that the unlicensed users can obtain an efficient sharing of the available channels. Simulation results are reported to demonstrate the performance and effectiveness of the suggested algorithm.

  • 214.
    Yao, Yong
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Popescu, Alexandru
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Popescu, Adrian
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    On prioritised opportunistic spectrum access in cognitive radio cellular networks2015In: European transactions on telecommunications, ISSN 1124-318X, E-ISSN 2161-3915, Vol. 27, no 2, p. 294-310Article in journal (Refereed)
    Abstract [en]

    Cognitive radio (CR) networks allow secondary users (SUs) to opportunistically access licensed spectrum, thus providing efficient use of radio resources. Different studies carried out on CR networks have focused on the procedure of spectrum handoff of SUs such as the data transmission in a communication that can be carried out in different channels. In this paper, we consider cellular networks enhanced with facilities for CR communication where a user with a call in progress moves across neighbouring cells, that is, the so-called inter-cell handoff. Our model assumes that the cell gives priority to inter-cell handoff calls over the calls originating within it. A finite queue is used in every cell for SUs, and a fixed number of buffer slots are reserved for the inter-handoff SU calls. With these considerations, we study the transmission performance of SUs by using Markov chains-based modelling approach. The numerical analysis is validated by simulation experiments. We also suggest a fuzzy logic-based hybrid decision-making algorithm to select the best solution for inter-handoff prioritisation. The goal is to optimise the transmission performance of SUs by leveraging their requirements on service completion throughput and waiting time in each cell. Copyright © 2014 John Wiley & Sons, Ltd.

  • 215.
    Yarrapothu, Sindhura
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Effectiveness of Backup and Disaster Recovery in Cloud: A Comparative study on Tape and Cloud based Backup and Disaster Recovery2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Context: Backup and Disaster Recovery, DR play a vital role in day-to-day IT operations. They define extensive aspects of business continuity plan in an enterprise. There is a continuous need to improve backup and recovery performance concerning attributes such as backup window size, high availability, security, etc. Definitive information is what enterprises strive for and rely upon to deviate from traditional methods towards advancing technologies, which are an intrinsic segment of business mundane actions.

    Objectives: In this study, we investigate Backup and DR plans on an enterprise level. They are compared in terms of performance metrics such as Recovery Time Objective, Recovery Point Objective, Time taken to backup, Time taken to recover and Total cost of ownership. Also, how CPU and memory utilization conduct differ in both tape-based, cloud-based Backup and DR.

    Methods: Literature study was the first step to formulate research questions by understanding present technologies in Backup and DR. This led us to conduct a survey for further understanding of challenges faced in industries gaining a more practical exposure. A case study was conducted in an enterprise to capture accurate values. An experiment had been deployed to compare performance of both scenarios and analyze which methodology elevates Backup and DR performance by overcoming challenges.

    Results: The results attained through this thesis encompass performance related metrics and also the load in terms of CPU and memory utilizations. Survey results were observed to gain better understanding of current technologies and challenges with Backup and DR in enterprises. The cloudbased backup has proved to be better in considered enterprise environment during experimentation in terms of RPO, RTO, CPU, memory utilizations and Total Cost of ownership.

    Conclusions: There have been numerous research works conducted on how backup and DR plans can be made better. But, they lack accurate information on how their performances vary, what all parameters can be improved by shifting towards advanced and contemporary methodologies withaddressing features such as scalability, flexibility and adaptability, which is provided in this study.

  • 216.
    Yellakonda, Amulya
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    DESIGN AND IMPLEMENTATION OF RICH COMMUNICATION SERVICE SCENARIO REPLAYER AND PERFORMANCE EVALUATION OF APPLICATION SERVICE2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Rich Communication Services(RCS) program is a GSM Association (GSMA) initiative to create inter-operator communication services based on IP Multimedia Subsystem (IMS) . This initiative came up as the Global Telecom Operators ́response to the decline in their revenues and to help compete ’Over The Top’(OTT) service providers such as Viber, whatsapp, etc. RCS is an universal standard, making it inter-operable between mul- tiple service providers unlike OTT services with closed communities. RCS services use IMS as the underlying architecture with a RCS stack imple- mented into Android background service which offers high level API. For the purpose of testing RCS stack functionality which is usually affected by external dependencies like third party vendors, or ISP customizations in real telecommunication scenario, there is a persistent demand for scenario replay tools that can recreate the range of test conditions similar to those experienced in live deployments. There is also a need to evaluate the per- formance of service provided by application servers in the network in-order to predict the factors affecting the RCS service in general.

    In this work, we propose a tool to address the RCS scenario repro- duction in a test environment. The tool is implemented within an automated test environment with full control on interaction with the RCS stack, hence the ability to replay the scenario in a controlled fashion. To achieve the goal, the tool replays trace interactively with the RCS stack in a stateful manner , it ensures no improper packet generation which is critical feature for test environments where protocol semantics accuracy is fundamental. A detailed demonstration of how the tool can be deployed in test environ- ments is stated. A novel approach is used to validate the effectiveness of the replayed scenario, the sequence of events and states are compared to those from the recorded scenario using a call-back service to indicate the state. The replayed scenario showed strong relationship with the recorded RCS scenario. The paper also presents a performance evaluation of Application service by considering the request-reponse times of Network Registration procedure. The obtained results show that the average time taken for the Registration process is 555 milliseconds and in few instances there exists larger deviations from this average value showing the faulty behavior of the Server which is most crucial during the debugging process for the developers. 

  • 217. Yeoh, Phee Lep
    et al.
    Elkashlan, Maged
    Duong, Trung Q.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Yang, Nan
    da Costa, Daniel Benevides
    Transmit Antenna Selection for Interference Management in Cognitive Relay Networks2014In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 63, no 7, p. 3250-3262Article in journal (Refereed)
    Abstract [en]

    We propose transmit antenna selection (TAS) in decode-and-forward (DF) relaying as an effective approach to reduce the interference in underlay spectrum sharing networks with multiple primary users (PUs) and multiple antennas at the secondary users (SUs). We compare two distinct protocols: 1) TAS with receiver maximal-ratio combining (TAS/MRC) and 2) TAS with receiver selection combining (TAS/SC). For each protocol, we derive new closed-form expressions for the exact and asymptotic outage probability with independent Nakagami-m fading in the primary and secondary networks. Our results are valid for two scenarios related to the maximum SU transmit power, i.e., P, and the peak PU interference temperature, i.e., Q. When P is proportional to Q, our results confirm that TAS/MRC and TAS/SC relaying achieve the same full diversity gain. As such, the signal-to-noise ratio (SNR) advantage of TAS/MRC relaying relative to TAS/SC relaying is characterized as a simple ratio of their respective SNR gains. When P is independent of Q, we find that an outage floor is obtained in the large P regime where the SU transmit power is constrained by a fixed value of Q. This outage floor is accurately characterized by our exact and asymptotic results.

  • 218.
    Yong, Yao
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Adrian, Popescu
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    On Prioritized Uplink Transmission in Cognitive Radio Mesh Networks2015Conference paper (Refereed)
    Abstract [en]

    In cognitive radio mesh networks, the unlicensed users are allowed to use spectrum opportunities under the restriction of protection of licensed users. The transmission operation of unlicensed users packets is typically done through multiple mesh routers. In the case of a large amount of packet retransmissions, the performance of the whole network system may degrade. To solve this problem, a queueing buffer based priority scheme for mesh routers is suggested. Based on this scheme, the uplink transmission performance of unlicensed users in cognitive radio mesh networks is studied under the condition of imperfect spectrum sensing. 

  • 219.
    Yong, Yao
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Adrian, Popescu
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    On the Performance of Uplink Transmission in Cognitive Radio Mesh Networks2015Conference paper (Refereed)
    Abstract [en]

    In cognitive radio mesh networks, the unlicensed users are allowed to use spectrum opportunities under the restriction of protection of licensed users. The transmission operation of unlicensed users packets is typically done through multiple mesh routers. In the case of a large amount of packet retransmissions, the performance of the whole network system may degrade. To solve this problem, a queueing buffer based priority scheme for mesh routers is suggested. Based on this scheme, the uplink transmission performance of unlicensed users in cognitive radio mesh networks is studied under the condition of imperfect spectrum sensing. Numerical evaluation results show the feasibility and effectiveness of the suggested priority scheme. 

  • 220. Yuen, Chau
    et al.
    Elkashlan, Maged
    Qian, Yi
    Duong, Trung Q.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Shu, Lei
    Schmidt, Frank
    ENERGY HARVESTING COMMUNICATIONS: PART III2015In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 53, no 8, p. 90-91Article in journal (Other academic)
  • 221.
    Zepernick, Hans-Jürgen
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Quality of Mobile Multimedia Experience: Past, Present and Future2014Conference paper (Refereed)
    Abstract [en]

    The rapid evolution of wireless networks is driven by the growth of wireless packet data applications such as interactive mobile multimedia applications, wireless streaming services, and video-on-demand. The largely heterogeneous network structures, severe channel impairments, and complex traffic patterns make the wireless networks much more unpredictable compared to their wired counterparts. One of the major challenges with the roll-out of these services is therefore the design of wireless networks that fulfill the stringent quality of service requirements of mobile multimedia applications. In this tutorial, we provide a survey on the evolution of quality of experience (QoE) concepts in the context of mobile multimedia systems touching on the past, present, and future aspects. Specifically, the ideas behind QoE are discussed and an overview of related standardization work and major research initiatives is provided. On this basis, QoE metrics for speech, image, and video are described. Given the increase on visual services, perceptual image and video quality metrics for real-time quality assessment of mobile multimedia experience are discussed. This includes a classification of quality assessment methods, comparison of psychophysical versus engineering approaches, perceptual image and video quality assessment, and some example applications. An outlook on future work and challenges is also provided.

  • 222.
    Zepernick, Hans-Jürgen
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Iqbal, Muhammad Imran
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Khatibi, Siamak
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Quality of Experience of Digital Multimedia Broadcasting Services: An Experimental Study2016In: 2016 IEEE Sixth International Conference on Communications and Electronics (ICCE), IEEE, 2016, p. 437-442Conference paper (Refereed)
    Abstract [en]

    Digital multimedia broadcasting (DMB), also know as mobile TV, has been developed as a digital radio transmission technology that supports multimedia services such as TV, radio and datacasting. Especially, the terrestrial version of DMB, referred to as T-DMB, has been widely deployed in South Korea to deliver multimedia services to mobile devices ranging from smartphones to laptops, car navigation systems, and telematic devices for automotives. Although T-DMB is claimed to theoretically work without difficulties in vehicles with speeds up to 300 km/h, in practice, occasional skips and other temporal and spatial artifacts have been observed. In this paper, we provide an experimental study of the Quality of Experience (QoE) of T-DMB with focus on TV services. The study is based on a measurement campaign that was conducted in a live T-DMB system in South Korea consisting of TV broadcasters and DMB receivers in vehicles. In particular, a comprehensive subjective test has been conducted on the DMB test material that was obtained in the measurement campaign. A statistical analysis of the user ratings obtained from the subjective tests is reported to quantify the QoE of T-DMB in terms of mean opinion scores (MOSs) and higher order statistics. The obtained results may be used to develop related QoE models for this type of systems and services. In particular, the results may suggest to exploit insights obtained from higher order statistics such as skewness and kurtosis into QoE modeling rather than considering only MOS and variance.

  • 223. Zinner, T.
    et al.
    Hossfeld, T.
    Fiedler, Markus
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Liers, F.
    Volkert, T.
    Kohndoker, R.
    Schatz, R.
    Requirement driven prospects for realizing user-centric network orchestration2015In: Multimedia tools and applications, ISSN 1380-7501, E-ISSN 1573-7721, Vol. 74, no 2, p. 413-437Article in journal (Refereed)
    Abstract [en]

    The Internet's infrastructure shows severe limitations when an optimal end user experience for multimedia applications should be achieved in a resource-efficiently way. In order to realize truly user-centric networking, an information exchange between applications and networks is required. To this end, network-application interfaces need to be deployed that enable a better mediation of application data through the Internet. For smart multimedia applications and services, the application and the network should directly communicate with each other and exchange information in order to ensure an optimal Quality of Experience (QoE). In this article, we follow a use-case driven approach towards user-centric network orchestration. We derive user, application, and network requirements for three complementary use cases: HD live TV streaming, video-on-demand streaming and user authentication with high security and privacy demands, as typically required for payed multimedia services. We provide practical guidelines for achieving an optimal QoE efficiently in the context of these use cases. Based on these results, we demonstrate how to overcome one of the main limitations of today's Internet by introducing the major steps required for user-centric network orchestration. Finally, we show conceptual prospects for realizing these steps by discussing a possible implementation with an inter-network architecture based on functional blocks.

  • 224.
    Özcan, Mehmet Batuhan
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Iro, Gabriel
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    PARAVIRTUALIZATION IMPLEMENTATION IN UBUNTU WITH XEN HYPERVISOR2014Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [en]

    With the growing need for efficiency, cost reduction, reduced disposition of outdated electronics components as well as scalable electronics components, and also reduced health effects of our daily usage of electronics components. Recent trend in technology has seen companies manufacturing these products thinking in the mentioned needs when manufacturing and virtualizations is one important aspect of it. The need to share resources, the need to use lesser workspace, the need to reduce cost of purchase and manufacturing are all part of achievements of virtualization techniques. For some people, setting up a computer to run different virtual machines at the same time can be difficult especially if they have no prior basic knowledge of working in terminal environment and hiring a skilled personnel to do the job can be expensive. The motivation for this thesis is to help people with little or no basic knowledge on how to set up virtual machine with Ubuntu operating system on XEN hypervisor.

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