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  • 151.
    Samarasekera, A. Chaminda J.
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Ha, D.B.
    Ngyen, H.K.
    Performance of cognitive decode-and-forward relaying systems over Weibull fading channels2014Conference paper (Refereed)
    Abstract [en]

    In this paper, the performance of dual-hop decode-and-forward (DF) cognitive relay networks over independent non-identically distributed (i.n.i.d.) Weibull fading channels are evaluated, in a spectrum sharing environment. Where the transmit power of the secondary network is governed by the maximum interference power that the primary networks' receiver can tolerate. The closed form outage probability (OP), symbol error probability (SEP) and the ergodic capacity under interference power constraints from the primary network over i.n.i.d. Weibull fading channels are derived using statistical characteristics of the signal-to-noise ratio (SNR). The analytical results are verified by Monte-Carlo simulation.

  • 152.
    Samarasekera, Andawattage
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Ha, D.B.
    Ngyen, H.K.
    Best relay selection for underlay cognitive relaying networks over Weibull fading channels2014Conference paper (Refereed)
    Abstract [en]

    In this paper, the performance of underlay cognitive dual-hop decode-and-forward (DF) multi-relay networks with best relay selection (BRS) over independent identically distributed (i.i.d.) Weibull fading channels is evaluated. The maximum transmit power of the secondary network is governed by the maximum interference power that the primary networks' receiver can tolerate. Specifically the closed-form outage probability (OP) with interference power constraints from the primary network is derived, using the statistical characteristics of the end-to-end signal-to-noise ratio (SNR). The analytical results have been verified by Monte-Carlo simulations

  • 153.
    Samuelsson, Jakob
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Tidqvist, Magnus
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Brottsförebyggande arbete kring klotter, skadegörelse och anlagda bränder på högstadieskolor2015Student thesis
    Abstract [sv]

    Syftet med rapporten är att bidra i kommunens arbete med att minska skadegörelse på deras skolor. Detta genom att ta fram ett analys och resultatsunderlag att grunda en handlingsplan på samt komma med åtgärdsförslag. Problemet identifierades tillsammans med kommunens säkerhetssamordnare. I enlighet med BRÅs metod “kunskap som metod” undersöktes problembilden. Problembilden kartlades genom en självdeklarationsstudie, intervju med rektor och inhämtande av uppgifter från de kommmunala förvaltningarna. Av problembilden framgår bland annat att skadegörelsen utförs av både elever på skolan och utomstående. Av de 175 elever som svarade på enkäten anger 17 % att de utfört någon form av skadegörelse. Eleverna som anger att de utfört skadegörelse anger som främsta anledning uttråkning eller missnöje riktat mot skolan. Även grupptryck anges av flera svarande. Rektorn ger en bild av att större delen av skadegörelsen utförs av en liten grupp elever eller före detta elever. Skolan kan också vara särskilt utsatt på grund av sin geografiska utformning och läge då den ligger i utkanten av samhället och nästan helt saknar insyn. Utifrån framtagen problembild genomfördes brainstorming och brainwriting för framtagning av potentiella åtgärder som kommunen sedan kan använda vid framtagande av åtgärdsplan.

  • 154.
    Sanaboyina, Tulasi Priyanka
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Performance Evaluation of Time series Databases based on Energy Consumption2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The vision of the future Internet of Things is posing new challenges due to gigabytes of data being generated everyday by millions of sensors, actuators, RFID tags, and other devices. As the volume of data is growing dramatically, so is the demand for performance enhancement. When it comes to this big data problem, much attention has been given to cloud computing and virtualization for their almost unlimited resource capacity, flexible resource allocation and management, and distributed processing ability that promise high scalability and availability. On the other hand, the variety of types and nature of data is continuously increasing. Almost without exception, data centers supporting cloud based services are monitored for performance and security and the resulting monitoring data needs to be stored somewhere. Similarly, billions of sensors that are scattered throughout the world are pumping out huge amount of data, which is handled by a database. Typically, the monitoring data consists time series, that is numbers indexed by time. To handle this type of time series data a distributed time series database is needed.

     

    Nowadays, many database systems are available but it is difficult to use them for storing and managing large volumes of time series data. Monitoring large amounts of periodic data would be better done using a database optimized for storing time series data. The traditional and dominant relational database systems have been questioned whether they can still be the best choice for current systems with all the new requirements. Choosing an appropriate database for storing huge amounts of time series data is not trivial as one must take into account different aspects such as manageability, scalability and extensibility. During the last years NoSQL databases have been developed to address the needs of tremendous performance, reliability and horizontal scalability. NoSQL time series databases (TSDBs) have risen to combine valuable NoSQL properties with characteristics of time series data from a variety of use-cases.

     

    In the same way that performance has been central to systems evaluation, energy-efficiency is quickly growing in importance for minimizing IT costs. In this thesis, we compared the performance of two NoSQL distributed time series databases, OpenTSDB and InfluxDB, based on the energy consumed by them in different scenarios, using the same set of machines and the same data. We evaluated the amount of energy consumed by each database on single host and multiple hosts, as the databases compared are distributed time series databases. Individual analysis and comparative analysis is done between the databases. In this report we present the results of this study and the performance of these databases based on energy consumption.

  • 155.
    SASANK, HYDERKHAN
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Performance analysis of TCP in KVM virtualized environment2015Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The requirement of high quality services is increasing day by day. So, in order to meet up with this requirement new technologies are being developed one of them being virtualization. The main agenda of introducing virtualization is that though virtualization needs more powerful devices to run the hypervisor, the technique also helps to increase consolidation which makes efficient use of resources like increase in the CPU utilization. The virtualization technique helps us to run more VM’s (Virtual Machine) on the same platform i.e. on the same hypervisor. In virtualization as number of VM’s share the CPU will there be any effect on the performance of TCP with the performance influencing factors of virtualization. While TCP being the most widely used protocol and most reliable protocol can performance of TCP vary if different TCP congestion control mechanism are used in the virtualized environment are the main aims of this research.

     

    In this study, we investigate the performance influencing factor of TCP in the virtualized environment and whether those influencing factors have any role to play with the performance of the TCP. Also which TCP congestion control mechanism is best suitable in order to download files when virtualization is used will be investigated by setting up a client-server test bed. The different TCP congestion control mechanism which have been used are CUBIC, BIC, Highspeed, Vegas, Veno, Yeah, Westwood, LP, Scalable, Reno, Hybla. Total download time has been compared in order to know which congestion control algorithm performs better in the virtualized environment.

     

    The method that has been used to carry out the research is by experimentation. That is by changing the RAM sizes and CPU cores which are the performance influencing factors in virtualization and then analyzing the total download time while downloading a file by changing the TCP congestion control mechanisms by running a single guest VM. Apart from changing only congestion control mechanisms the other network parameters which effect the performance of the TCP such as Delay have been injected while downloading the file, to match up with the real time scenarios.

     

    Results collected include average download time of a file by changing the different memory sizes and different CPU cores. Average Download time for different TCP congestion controls mechanisms with inclusion of the parameter that effects the total download time such as Delay.

     

    From the results we got we can see that there is a slight influence on the performance of TCP by the performance influencing factors memory sizes and CPU cores allotted to the VM in the KVM virtualized environment and of all the TCP congestion control algorithms having TCP – BIC and TCP- YEAH performs the best in the KVM virtualized environment. The performance of TCP – LP is the least in the KVM virtualized environment.

  • 156.
    Sathvik, Katam
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Performance Tuning of Big Data Platform: Cassandra Case Study2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Usage of cloud-based storage systems gained a lot of prominence in fast few years. Every day millions of files are uploaded and downloaded from cloud storage. This data that cannot be handled by traditional databases and this is considered to be Big Data. New powerful platforms have been developed to store and organize big and unstructured data. These platforms are called Big Data systems. Some of the most popular big data platform are Mongo, Hadoop, and Cassandra. In this, we used Cassandra database management system because it is an open source platform that is developed in java. Cassandra has a masterless ring architecture. The data is replicated among all the nodes for fault tolerance. Unlike MySQL, Cassandra uses per-column basis technique to store data. Cassandra is a NoSQL database system, which can handle unstructured data. Most of Cassandra parameters are scalable and are easy to configure.

    Amazon provides cloud computing platform that helps a user to perform heavy computing tasks over remote hardware systems. This cloud computing platform is known as Amazon Web Services. AWS services also include database deployment and network management services, that have a non-complex user experience. In this document, a detailed explanation on Cassandra database deployment on AWS platform is explained followed by Cassandra performance tuning.   

    In this study impact on read and write performance with change Cassandra parameters when deployed on Elastic Cloud Computing platform are investigated. The performance evaluation of a three node Cassandra cluster is done. With the knowledge of configuration parameters a three node, Cassandra database is performance tuned and a draft model is proposed.

                A cloud environment suitable for the experiment is created on AWS. A three node Cassandra database management system is deployed in cloud environment created. The performance of this three node architecture is evaluated and is tested with different configuration parameters. The configuration parameters are selected based on the Cassandra metrics behavior with the change in parameters. Selected parameters are changed and the performance difference is observed and analyzed. Using this analysis, a draft model is developed after performance tuning selected parameters. This draft model is tested with different workloads and compared with default Cassandra model.

    The change in the key cache memory and memTable parameters showed improvement in performance metrics. With increases of key cache size and save time period, read performance improved. This also showed effect on system metrics like increasing CPU load and disk through put, decreasing operation time and

    The change in memTable parameters showed the effect on write performance and disk space utilization. With increase in threshold value of memTable flush writer, disk through put increased and operation time decreased. The draft derived from performance evaluation has better write and read performance.

  • 157. Schatz, Raimund
    et al.
    Fiedler, Markus
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Skorin-Kapov, Lea
    QoE-Based Network and Application Management2014In: QUALITY OF EXPERIENCE: ADVANCED CONCEPTS, APPLICATIONS AND METHODS / [ed] Moller, S.; Raake, A., Springer , 2014, p. 411-426Chapter in book (Refereed)
    Abstract [en]

    This chapter presents an overview of a set of recently proposed QoE-based management approaches that all try so resolve a central dilemma: maximizing user satisfaction while at the same time maximizing resource efficiency and economy. To this end, it first builds bridges between recent approaches towards QoE-based Network Management and standardized Network Management functions. This is contrasted by a discussion of recent approaches towards QoE-based Application Management. Further, it is shown how both Network Management and Application Management can work together in concert. Finally, open issues regarding a better integration of management and QoE are outlined.

  • 158.
    Shahid, Muhammad
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Applied Signal Processing.
    Khatibi, Siamak
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Tuemay, Yared
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Popularity index through video semantic quality assessment2014Conference paper (Refereed)
    Abstract [en]

    Popularity of the streaming media content such as videos can be ascribed to the perceptual quality, to some extent, of the content. The traditional methods of audio/video quality assessment lack in provision of the input from higher cognitive of the human perception. Some studies have revealed that liking or disliking of a certain content can bias the human judgement towards video quality. In this paper, we have examined the impact of the use of semantic quality indicators namely audio content, audio quality, video content, and video quality in the assessment of quality of a video. Further, we have proposed a methodology to use these indicators for designing a prediction model for the popularity of streaming videos.

  • 159.
    Shahid, Muhammad
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Applied Signal Processing.
    Rossholm, Andreas
    Blekinge Institute of Technology, Faculty of Engineering, Department of Applied Signal Processing.
    Lövström, Benny
    Blekinge Institute of Technology, Faculty of Engineering, Department of Applied Signal Processing.
    Zepernick, Hans-Jürgen
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    No-reference image and video quality assessment: a classification and review of recent approaches2014In: EURASIP Journal on Image and Video Processing, ISSN 1687-5176, E-ISSN 1687-5281, Vol. 2014, no 40Article, review/survey (Refereed)
    Abstract [en]

    The field of perceptual quality assessment has gone through a wide range of developments and it is still growing. In particular, the area of no-reference (NR) image and video quality assessment has progressed rapidly during the last decade. In this article, we present a classification and review of latest published research work in the area of NR image and video quality assessment. The NR methods of visual quality assessment considered for review are structured into categories and subcategories based on the types of methodologies used for the underlying processing employed for quality estimation. Overall, the classification has been done into three categories, namely, pixel-based methods, bitstream-based methods, and hybrid methods of the aforementioned two categories. We believe that the review presented in this article will be helpful for practitioners as well as for researchers to keep abreast of the recent developments in the area of NR image and video quality assessment. This article can be used for various purposes such as gaining a structured overview of the field and to carry out performance comparisons for the state-of-the-art methods.

  • 160.
    Shaik, Jani Saida
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Simulation‐Based Comparative Study of Routing Protocols for Wireless Ad-­Hoc Network2015Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Wireless ad-hoc networks have recently gained significant research attention due to their vast potential of applications in numerous fields. Multihop routing is a significantly important aspect which determines, to a large extend, the overall performance of the network. A number of routing protocols have been proposed for routing in wireless ad-hoc networks with focus on optimizing different aspects of the network routing. This report focuses on studying two popular protocols for wireless networks: Ad-hoc On Demand Distance Vector (AODV) and Optimized Link-State Routing (OLSR). The two protocols belong to different classes of routing categorization. AODV is a popular on-demand (reactive) routing protocol whereas the OLSR is a popular link-state based proactive routing protocol. The technical aspects of the two protocols shall be studied while highlighting the differences between the two and simulation based performance comparison of the two protocols shall be carried out under varying traffic and network conditions using the Network Simulator.

  • 161.
    Shaikh, Junaid
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Fiedler, Markus
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Paul, Pangkaj
    Egger, Sebastian
    Guyard, Frederic
    Back to Normal? Impact of Temporally Increasing Network Disturbances on QoE2013Conference paper (Refereed)
    Abstract [en]

    Brief episodes of network faults and performance issues adversely affect the user Quality of Experience (QoE). Besides damaging the current opinions of users, these events may also shape user’s future perception of the service. Therefore, it is important to quantify the impact of such events on QoE over time. In this paper, we present our findings on the temporal aspects of user feedback to disturbances on networks. These findings are based on subjective user tests performed in the context of web browsing on an e-commerce website. The results of this study suggest that the QoE drops significantly every time the page load time grows. The after-effects of network disturbances on user QoE remain visible even when the network problems are over, i.e., users do not immediately return to the same level of opinion scores as compared to the corresponding pre-disturbance phase. They tend to remember their recent experiences. Our results also show that there are four segments of users that exist with regards to their feedback to page load times. Network operators may customize their services according to each segment of users to raise the overall QoE. Finally, we show that the exponential relationship provides best fits of QoE and page load times for all segments of users.

  • 162.
    Shirinbab, Sogand
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Lundberg, Lars
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Ilie, Dragos
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Performance Comparison of KVM, VMware and XenServer using a Large Telecommunication Application2014Conference paper (Refereed)
    Abstract [en]

    One of the most important technologies in cloud computing is virtualization. This paper presents the results from a performance comparison of three well-known virtualization hypervisors: KVM, VMware and XenServer. In this study, we measure performance in terms of CPU utilization, disk utilization and response time of a large industrial real-time application. The application is running inside a virtual machine (VM) controlled by the KVM, VMware and XenServer hypervisors, respectively. Furthermore, we compare the three hypervisors based on downtime and total migration time during live migration. The results show that the Xen hypervisor results in higher CPU utilization and thus also lower maximum performance compared to VMware and KVM. However, VMware causes more write operations to disk than KVM and Xen, and Xen causes less downtime than KVM and VMware during live migration. This means that no single hypervisor has the best performance for all aspects considered here.

  • 163.
    Shirmohamadi, Bamshad
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Fiedler, Markus
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Bridging between Quality of Experience and Quality of Service through TCP Flag Ratios2016In: Proceedings - Conference on Local Computer Networks, LCN, IEEE Computer Society , 2016, Vol. Part F126504, p. 192-198, article id 7856156Conference paper (Refereed)
    Abstract [en]

    Since the early days of Quality of Experience (QoE) research, relationships to Quality of Service (QoS) and corresponding QoE-QoS models have been of great interest to the research community. However, the manifold quality transformations throughout the communication stack, together with accessibility issues of QoS parameters inside networks, hamper availability, applicability and generality of such models. On this background, the paper proposes the use of specific transport layer information, in particular the ratios of selected flags used by the TCP protocol, as QoE indicators. In our work, we show that such flag ratios help identifying, characterizing and quantifying user annoyance from observations anywhere along the TCP connection. As use case, we address video streaming from a TCP CUBIC web server in a wireless setting. © 2016 IEEE.

  • 164.
    Sibomana, Louis
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Performance Analysis of Cognitive Radio Networks under Spectrum Sharing and Security Constraints2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The cognitive radio network (CRN) concept has been proposed as a solution to the growing demand and underutilization of the radio spectrum. To improve the radio spectrum utilization, CRN technology allows the coexistence of licensed and unlicensed systems over the same spectrum. In an underlay spectrum sharing system, secondary users (SUs) transmit simultaneously with the primary users (PUs) in the same frequency band given that the interference caused by the SU to the PU remains below a tolerable interference limit. Besides the transmission power limitation, a secondary network is subject to distinct channel impairments such as fading and interference from the primary transmissions. Also, CRNs face new security threats and challenges due to their unique cognitive characteristics.This thesis analyzes the performance of underlay CRNs and underlay cognitive relay networks under spectrum sharing constraints and security constraints. Distinct SU transmit power policies are obtained considering various interference constraints such as PU outage constraint or PU peak interference power constraint.

    The thesis is divided into an introduction and two research parts based on peer-reviewed publications. The introduction provides an overview of radio spectrum management, basic concepts of CRNs, and physical layer security. In the first research part, we study the performance of underlay CRNs with emphasis on a multiuser environment.In Part I-A, we consider a secondary network with delay-tolerant applications and analyze the ergodic capacity. Part I-B analyzes the secondary outage capacity which characterises the maximum data rate that can be achieved over a channel for a given outage probability. In Part I-C, we consider a secondary network with delay constrained applications, and derive expressions of the outage probability and delay-limited throughput. Part I-D presents a queueing model that provides an analytical tool to evaluate the secondary packet-level performance with multiple classes of traffic considering general interarrival and service time distributions. Analytical expressions of the SU average packet transmission time, waiting time in the queue, andtime spent in the system are provided.In the second research part, we analyze the physical layer security for underlay CRNs and underlay cognitive relay networks. Analytical expressions of the probability of non-zero secrecy capacity and secrecy outage probability are derived.Part II-A considers a single hop underlay CRN in the presence of multiple eavesdroppers (EAVs) and multiple SU-Rxs. In Part II-B, an underlay cognitive relay network in the presence of multiple secondary relays and multiple EAVs is studied.Numerical examples illustrate that it is possible to exploit the physical layer characteristics to achieve both security and quality of service in CRNs while satisfying spectrum sharing constraints.

  • 165.
    Sibomana, Louis
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Tran, Hung
    Tran, Quang Anh
    Impact of secondary user communication on security communication of primary user2015In: Security and Communication Networks, ISSN 1939-0114, E-ISSN 1939-0122, Vol. 8, no 18, p. 4177-4190Article in journal (Refereed)
    Abstract [en]

    Cognitive radio network concept has been considered as a promising solution to improve the spectrum utilization. However, it may be vulnerable to security problems as the primary user (PU) and secondary user (SU) access the same resource. In this paper, we consider a system model where an eavesdropper (EAV) illegally listens to the PU communication in the presence of a SU transmitter (SU-Tx) communicating with a SU receiver (SU-Rx). The SU-Tx transmit power is subject to the peak transmit power constraint of the SU and outage probability constraint of the PU. Given this context, the effect of the interference from the SU-Tx to the EAV on the primary system security is investigated. In particular, analytical expressions of the probability of existence of non-zero secrecy capacity and secrecy outage probability of the PU are derived. Moreover, the performance analysis of the secondary network is examined where closed-form expressions of the symbol error probability and achievable rate are presented. Numerical examples are provided to evaluate the impact of the primary system parameters and channel conditions among users on the system performance of secondary and primary networks. Interestingly, our results reveal a fact that the security of the primary network strongly depends on the channel condition of the SU-Tx to the EAV link and the transmit power policy of the SU-Tx. Copyright (C) 2015 John Wiley & Sons, Ltd.

  • 166.
    Sibomana, Louis
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Tran, Hung
    Zepernick, Hans-Jürgen
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    On Physical Layer Security for Cognitive Radio Networks with Primary User Interference2015Conference paper (Refereed)
    Abstract [en]

    In this paper, we investigate the secondary network physical layer security under the outage constraint of the primary user (PU) receiver and interference from the PU transmitter to the secondary network. In particular, a secondary user (SU) transmitter sends confidential messages to trusted multiple SU receivers (SU-Rxs) in the presence of multiple eavesdroppers (EAVs). Further, we exploit multiuser diversity where the SU-Rx with best channel condition is scheduled for transmission. Then, analytical expressions of the probability of existence of non-zero secrecy capacity and secrecy outage probability are obtained. Analytical and simulation results are provided to evaluate the effect of the number of SU-Rxs and number of EAVs on the secondary system. Interestingly, the numerical results show that the interference from the primary network to the secondary network is an important parameter to improve the secondary network security.

  • 167.
    Sibomana, Louis
    et al.
    University of Rwanda, RWA.
    Zepernick, Hans-Jürgen
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Ergodic capacity of multiuser scheduling in cognitive radio networks: Analysis and comparison2016In: Wireless Communications & Mobile Computing, ISSN 1530-8669, E-ISSN 1530-8677, Vol. 16, no 16, p. 2759-2774Article in journal (Refereed)
    Abstract [en]

    This paper analyzes the ergodic capacity of secondary point-to-multipoint communications under the outage constraint of multiple primary user receivers (PU-Rxs) and the secondary user (SU) maximum transmit power limit. We first derive analytical expressions of the ergodic capacity for three scheduling schemes, that is, round robin, Max-signal-to-interference-plus-noise-ratio (Max-SINR) and Min-SINR, and compare their performance. Numerical examples show that when the number of SU receivers (SU-Rxs) increases in the presence of a single PU-Rx and at high SINR, the Min-SINR outperforms the Max-SINR scheme. As the number of PU-Rxs increases, the Max-SINR performs better than the Min-SINR scheduling. When the number of SU-Rxs becomes large, the system capacity is enhanced but so is the feedback load. To exploit the Max-SINR transmission while reducing the feedback load, we assume a threshold based on the channel quality where the SU-Rxs with the instantaneous SINR above the threshold participate in the Max-SINR scheduling; otherwise, an SU-Rx is selected randomly. Then, an analytical expression of the average capacity is derived. Numerical results illustrate that the capacity with limited feedback is approximately the same as for the case of Max-SINR with full feedback when the SU threshold for feedback condition is set to low and medium values.

  • 168.
    Sibomana, Louis
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Zepernick, Hans-Jürgen
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Hung, Tran
    Wireless Information and Power Transfer in an Underlay Cognitive Radio Network2014In: 2014 8TH INTERNATIONAL CONFERENCE ON SIGNAL PROCESSING AND COMMUNICATION SYSTEMS (ICSPCS), IEEE, 2014Conference paper (Refereed)
    Abstract [en]

    In this paper, we consider a secondary network with simultaneous wireless information and power transfer in a spectrum sharing scenario. In particular, a secondary user (SU) transmitter communicates with multiple SU receivers (SU-Rxs) under the peak interference power constraint of the primary user receiver and the SU maximum transmit power limit. We apply a channel quality-based threshold and exploit opportunistic scheduling. Specifically, an SU-Rx with best channel condition among a set of SU-Rxs satisfying the threshold is scheduled for data transmission. The remaining SU-Rxs with channel condition below the threshold, harvest the radio frequency energy. Analytical expressions of the SU ergodic capacity, symbol error rate, throughput, and energy harvesting are obtained. An optimal threshold satisfying a given target outage probability is determined. Numerical results are provided to investigate the impact of different parameters on the secondary network performance.

  • 169.
    Sibomana, Louis
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Zepernick, Hans-Jürgen
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Tran, Hung
    Achievable Secrecy Capacity in an Underlay Cognitive Radio Network2014Conference paper (Refereed)
    Abstract [en]

    In this paper, we consider a spectrum sharing cognitive radio network where a secondary user (SU) transmitter (SU-Tx) communicates with multiple SU receivers (SU-Rxs). There exist multiple eavesdroppers (EAVs) who illegally listen to the secondary network communication. Further, the primary network consists of a primary user (PU) transmitter serving multiple PU receivers. In particular, the SU-Tx transmit power is subject to the joint constraint of PU outage and SU maximum transmit power limit. Moreover, we investigate the secondary network physical layer security in terms of average secrecy capacity for both cases of known and unknown channel information of the EAV at the SU-Tx. Numerical results are provided to evaluate the impact of the number of PU-Rxs, number of EAVs, number of SU-Rxs, and channel mean powers among users on the SU average secrecy capacity.

  • 170.
    Sibomana, Louis
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Zepernick, Hans-Jürgen
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Tran, Hung
    On Physical Layer Security for Reactive DF Cognitive Relay Networks2014Conference paper (Refereed)
    Abstract [en]

    This paper analyzes the physical layer security for cognitive relay networks under the peak interference power constraint of the primary user receiver. In particular, a secondary user (SU) transmitter communicates with an SU receiver through the help of multiple secondary relays (SRs) using a decode-and- forward (DF) protocol. There exist multiple eavesdroppers (EAVs) who illegally listen to the secondary network communication. We consider a reactive DF scheme, and only the SRs that satisfy a decoding threshold participate in the relay selection. Analytical expressions of the probability of existence of secrecy capacity and secrecy outage probability are obtained. Numerical results are provided to evaluate the impact of the number of SRs, number of EAVs and channel mean powers on the secondary system security. We also investigate the effect of the interference from the primary network to the secondary network performance. Moreover, the performance of proactive DF is analyzed for the purpose of comparison.

  • 171.
    Siddiqui, Rafid
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    On Fundamental Elements of Visual Navigation Systems2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Visual navigation is a ubiquitous yet complex task which is performed by many species for the purpose of survival. Although visual navigation is actively being studied within the robotics community, the determination of elemental constituents of a robust visual navigation system remains a challenge. Motion estimation is mistakenly considered as the sole ingredient to make a robust autonomous visual navigation system and therefore efforts are made to improve the accuracy of motion estimations. On the contrary, there are other factors which are as important as motion and whose absence could result in inability to perform seamless visual navigation such as the one exhibited by humans. Therefore, it is needed that a general model for a visual navigation system be devised which would describe it in terms of a set of elemental units. In this regard, a set of visual navigation elements (i.e. spatial memory, motion memory, scene geometry, context and scene semantics) are suggested as building blocks of a visual navigation system in this thesis. A set of methods are proposed which investigate the existence and role of visual navigation elements in a visual navigation system. A quantitative research methodology in the form of a series of systematic experiments is conducted on these methods. The thesis formulates, implements and analyzes the proposed methods in the context of visual navigation elements which are arranged into three major groupings; a) Spatial memory b) Motion Memory c) Manhattan, context and scene semantics. The investigations are carried out on multiple image datasets obtained by robot mounted cameras (2D/3D) moving in different environments. Spatial memory is investigated by evaluation of proposed place recognition methods. The recognized places and inter-place associations are then used to represent a visited set of places in the form of a topological map. Such a representation of places and their spatial associations models the concept of spatial memory. It resembles the humans’ ability of place representation and mapping for large environments (e.g. cities). Motion memory in a visual navigation system is analyzed by a thorough investigation of various motion estimation methods. This leads to proposals of direct motion estimation methods which compute accurate motion estimates by basing the estimation process on dominant surfaces. In everyday world, planar surfaces, especially the ground planes, are ubiquitous. Therefore, motion models are built upon this constraint. Manhattan structure provides geometrical cues which are helpful in solving navigation problems. There are some unique geometric primitives (e.g. planes) which make up an indoor environment. Therefore, a plane detection method is proposed as a result of investigations performed on scene structure. The method uses supervised learning to successfully classify the segmented clusters in 3D point-cloud datasets. In addition to geometry, the context of a scene also plays an important role in robustness of a visual navigation system. The context in which navigation is being performed imposes a set of constraints on objects and sections of the scene. The enforcement of such constraints enables the observer to robustly segment the scene and to classify various objects in the scene. A contextually aware scene segmentation method is proposed which classifies the image of a scene into a set of geometric classes. The geometric classes are sufficient for most of the navigation tasks. However, in order to facilitate the cognitive visual decision making process, the scene ought to be semantically segmented. The semantic of indoor scenes as well as semantic of the outdoor scenes are dealt with separately and separate methods are proposed for visual mapping of environments belonging to each type. An indoor scene consists of a corridor structure which is modeled as a cubic space in order to build a map of the environment. A “flash-n-extend” strategy is proposed which is responsible for controlling the map update frequency. The semantics of the outdoor scenes is also investigated and a scene classification method is proposed. The method employs a Markov Random Field (MRF) based classification framework which generates a set of semantic maps.

  • 172.
    Siddiqui, Rafid
    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.
    Bio-inspired Metaheuristic based Visual Tracking and Ego-motion Estimation2014Conference paper (Refereed)
    Abstract [en]

    The problem of robust extraction of ego-motion from a sequence of images for an eye-in-hand camera configuration is addressed. A novel approach toward solving planar template based tracking is proposed which performs a non-linear image alignment and a planar similarity optimization to recover camera transformations from planar regions of a scene. The planar region tracking problem as a motion optimization problem is solved by maximizing the similarity among the planar regions of a scene. The optimization process employs an evolutionary metaheuristic approach in order to address the problem within a large non-linear search space. The proposed method is validated on image sequences with real as well as synthetic image datasets and found to be successful in recovering the ego-motion. A comparative analysis of the proposed method with various other state-of-art methods reveals that the algorithm succeeds in tracking the planar regions robustly and is comparable to the state-of-the art methods. Such an application of evolutionary metaheuristic in solving complex visual navigation problems can provide different perspective and could help in improving already available methods.

  • 173.
    Siddiqui, Rafid
    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.
    Robust Place Recognition with an Application to Semantic Topological Mapping2013Conference paper (Refereed)
    Abstract [en]

    The problem of robust and invariant representation of places is being addressed. A place recognition technique is proposed followed by an application to a semantic topological mapping. The proposed technique is evaluated on a robot localization database which consists of a large set of images taken under various weather conditions. The results show that the proposed method can robustly recognize the places and is invariant to geometric transformations, brightness changes and noise. The comparative analysis with the state-of-the-art semantic place description methods show that the method outperforms the competing methods and exhibits better average recognition rates.

  • 174.
    Siddiqui, Rafid
    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.
    Robust Visual Odometry Estimation of Road Vehicle from Dominant Surfaces for Large Scale Mapping2015In: IET Intelligent Transport Systems, ISSN 1751-956X, E-ISSN 1751-9578, Vol. 9, no 3, p. 314-322Article in journal (Refereed)
    Abstract [en]

    Every urban environment contains a rich set of dominant surfaces which can provide a solid foundation for visual odometry estimation. In this work visual odometry is robustly estimated by computing the motion of camera mounted on a vehicle. The proposed method first identifies a planar region and dynamically estimates the plane parameters. The candidate region and estimated plane parameters are then tracked in the subsequent images and an incremental update of the visual odometry is obtained. The proposed method is evaluated on a navigation dataset of stereo images taken by a car mounted camera that is driven in a large urban environment. The consistency and resilience of the method has also been evaluated on an indoor robot dataset. The results suggest that the proposed visual odometry estimation can robustly recover the motion by tracking a dominant planar surface in the Manhattan environment. In addition to motion estimation solution a set of strategies are discussed for mitigating the problematic factors arising from the unpredictable nature of the environment. The analyses of the results as well as dynamic environmental strategies indicate a strong potential of the method for being part of an autonomous or semi-autonomous system.

  • 175.
    Siddiqui, Rafid
    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.
    Semantic Urban Maps2014In: International Conference on Pattern Recognition, IEEE , 2014, p. 4050-4055Conference paper (Refereed)
    Abstract [en]

    A novel region based 3D semantic mapping method is proposed for urban scenes. The proposed Semantic Urban Maps (SUM) method labels the regions of segmented images into a set of geometric and semantic classes simultaneously by employing a Markov Random Field based classification framework. The pixels in the labeled images are back-projected into a set of 3D point-clouds using stereo disparity. The point-clouds are registered together by incorporating the motion estimation and a coherent semantic map representation is obtained. SUM is evaluated on five urban benchmark sequences and is demonstrated to be successful in retrieving both geometric as well as semantic labels. The comparison with relevant state-of-art method reveals that SUM is competitive and performs better than the competing method in average pixel-wise accuracy.

  • 176.
    Soffritti, Jacopo
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Duong, Trung Q.
    Merani, Maria Luisa
    Zepernick, Hans-Jürgen
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Performance Analysis of Randomized Distributed Space-Time Codes over Composite Gamma/Lognormal Fading Channels2014Conference paper (Refereed)
    Abstract [en]

    This work investigates the end-to-end performance of randomized distributed space-time codes with complex Gaussian distribution, when employed in a wireless relay network. The relaying nodes are assumed to adopt a decode-and-forward strategy and transmissions are affected by small and large scale fading phenomena. Extremely tight, analytical approximations of the end-to-end symbol error probability and of the end-to-end outage probability are derived and successfully validated through Monte-Carlo simulation. For the high signal-to-noise ratio regime, a simple, closed-form expression for the symbol error probability is further provided.

  • 177.
    Sravani, Kancharla
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Study on Energy saving in Wireless Mesh Networks Using Network Simulator - 32016Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Context: Wireless Mesh Network (WMN) is a form of ad-hoc network with flexible backhaul infrastructure and configuration, provides adaptive wireless internet connectivity to end users with high reliability. WMN is a wireless network consisting of mesh clients, mesh routers and gateways which are organized in a mesh topology with decentralized nature can consume more energy for data transmission. The networking performance of WMNs can be degraded due to the fact of high energy consumption for data transmission. Therefore, energy efficiency is the primary factor for attaining eminent performance. Organizing efficient routing and proper resource allocation can save huge amount of energy.

    Objectives: The main goal of this thesis is to reduce the energy consumption in WMNs. To do this, a new energy efficient routing algorithm is suggested. Adaptive rates based on rate allocation strategy and end to end delay metric are used mainly for optimal path selection in routing, which may in turn reduces the resource utilization and energy consumption.

    Method: An energy efficient routing algorithm is implemented by using the Ad hoc OnDemand Distance Vector (AODV) routing protocol. The RREQ packet in AODV is modified by adding a new field known as delay parameter which measures end to end delay between nodes. Adaptive rates obtained from Rate allocation policy are considered in the routing process to reduce energy consumption in the network. Energy measurement of the WMN and its performance is evaluated by measuring the metrics such as Throughput, End-to-End delay, Packet Delivery Ratio (PDR). For performing the simulation process, in this thesis, Network Simulator - 3 (NS-3) which is an open source discrete-event network simulator in which simulation models can be executed in C++ and Python is used. Using NetAnim-3.107 animator in NS-3-25.1, traffic flows between all the nodes are displayed.

    Results: The results are taken for existing algorithm and proposed algorithm for 25,50,75 and 100 nodes. Comparison of results shows that the total energy consumption is reduced for proposed algorithm for in all four scenarios. Conclusion: Energy efficient routing algorithm is implemented in different scenarios of radio access networks and energy is saved. Due to this algorithm even the performance metrics, Throughput, End-to-End delay, Packet Delivery Ratio (PDR) have shown eminent performance.

  • 178.
    Sriram Prashanth, Naguru
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    OpenFlow Switching Performance using Network Simulator - 32016Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Context. In the present network inventive world, there is a quick expansion of switches and protocols, which are used to cope up with the increase in customer requirement in the networking. With increasing demand for higher bandwidths and lower latency and to meet these requirements new network paths are introduced. To reduce network load in present switching network, development of new innovative switching is required. These required results can be achieved by Software Define Network or Traditional layer-3 technologies.Objectives. In this thesis, the end to end (e2e) transmission performance of OpenFlow and Layer-3 switches and their dynamic characteristics are investigated using network simulation.Methods. To replicate real life network topology and evaluate e2e transmission performance, a simulation based test-bed is implemented for both OpenFlow switch and layer-3 switch. The test beds are implemented using Network Simulator-3 (NS3). A two-tire network topology is designed with specified components for performance evaluation.Results. The performance metrics like throughput, average delay, simulation time and Packet Delivery Ratio (PDR) are measured, results are analyzed statistically and are compared. The behavior of network traffic in both the topologies are understood using NS-3 and explained further in the thesis.Conclusions. The analytical and statistical results from simulation show that OpenFlow switching performs relatively better than layer-3 switching.

  • 179.
    Stalidis, Geo
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Blönnigen, Patrik
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Flygsäkerhet: Säkerhetsrutiner och tillämpningar för flygsäkerhet2013Student thesis
    Abstract [sv]

    År 2001, den 11e september, skakades hela världen av ett terrorattentat av en omfattning som man aldrig tidigare hade upplevt, där flygplan användes som vapen i flera välkoordinerade attacker som krävde drygt 3000 människors liv. Detta ledde till en omfattande reformation och kapprustning inom säkerhetsvärlden, speciellt avseende flygsäkerheten på flygplatser, för att garantera att en sådan attack inte skulle gå att genomföra igen. I den här uppsatsen tar vi upp frågor om flygsäkerhet, där vi med flygsäkerhet avser de metoder och tekniska lösningar som används för att skydda personal, passagerare, flygplan och själva flygplatsen mot oavsiktlig och avsiktlig skada samt brottslighet och andra hot. Framför allt fokuserar vi på flygplatssäkerhet samt på situationen i USA. Målet med flygplatssäkerheten är att skydda flygplatsen, planen, landet, anställda och allmänheten från skador, samt att bidra till den nationella säkerheten och kampen mot terrorism. I uppsatsen undersöker vi och diskuterar balansen mellan existerande risker, hot och flygsäkerhet. Vi kartlägger större flygsäkerhetsincidenter som ägt rum under senare år, utöver 9/11 attacken. Vidare undersöker vi de efterdyningar inom flygsäkerhet som skapades av 9/11 attacken. Slutligen diskuterar vi om dagens säkerhetspådrag till följd av 9/11 attacken är uttryck för hysteri eller kan ses som adekvata åtgärder, givet de hot mot flygsäkerheten som finns. Metoden utgörs av en kvalitativ litteraturstudie där vi har gått igenom styrande verk, intervjuer och undersökningar inom ämnesområdet. Resultatet av vår litteraturstudie tyder på att hotet om terrorism överdrivits. En ansenlig del av de åtgärder som sattes in efter 9/11 attacken för att förstärka flygsäkerheten skulle kunna klassificeras som "säkerhetsteater", det vill säga åtgärder som inte åstadkommer något utan är utformade för att få den ansvariga regeringen att se bra ut och att få det att se ut som om de arbetar med problemet. Däremot har den ökade medvetenheten hos allmänheten om risken för terrorattacker med dödlig utgång som 9/11 attacken resulterade i medfört att passagerare idag är beredda att göra aktivt motstånd mot kapare på ett annat sätt än tidigare. Detta är förmodligen en av de viktigaste anledningarna till att flygsäkerheten har ökat idag.

  • 180.
    Sun, Zhichao
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Feasibility Study of a SLA Driven Transmission Service2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Network based services are expanding scale at an unprecedented speed currently. With the continuously strengthen of user’s dependence on these, performance issues are becoming more and more important. Service Level Agreement (SLA) is a negotiated contract between service provider and customer in the way of service quality, priority, responsibility, etc.

    In this thesis, we designed and implemented a prototype for a SLA driven transmission service, which can deliver a file from one host to another, using a combination of different transport protocols. The proposed service measures the network conditions, and based on these and user’s requirement, it dynamically evaluates if it can meet the user SLA. Once a transmission has been accepted, it uses this information to adjust the usage of different transfer layer protocols, in order to meet the agreed SLA.

    The thesis work is based on the investigating of network theory and experimental results. We research how the SLA driven transmission service is affected by various factors, they include user’s requirements, network conditions, and service performance, etc. We design and implement an evaluation model for the network performance. It reveals how network performance is influenced by different network metrics, such as Round-Trip-Time (RTT), Throughput, and Packet Loss Rate (PLR), etc. We implement a transmission service on real test-bed, which is a controllable environment. We can alter the network metrics and measuring frequency of our evaluation model. Then, we evaluate these changes with our evaluation model and improve the performance of the transmission service. After that, we propose a calculating method for the service cost. At last, we can summarize the feasibility of this SLA driven transmission service.

    In the experiments, we obtain the variable delivery time and packet loss of the transmission service, which are changed with RTT and PLR of network. We analyze the different performance of transmission service, which uses TCP, UDP, and SCTP separately. Also a suitable measuring frequency and the cost for the usage of transmission service on this frequency are pointed out.

    Statistical analysis on the experiment results show that such SLA driven transmission service is feasible. It brings improved performance for user’s requirements. In addition, we come up with some useful suggestions and future work for the transmission service.

  • 181.
    TADESSE, ADDISHIWOT
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Efficient Bare Metal Backup and Restore in OpenStack Based Cloud InfrastructureDesign: Implementation and Testing of a Prototype2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 182.
    Tamanampudi, Monica
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Sannareddy, Mohith Kumar Reddy
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Performance Optimization of a Service in Virtual and Non - Virtual Environment2019Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    In recent times Cloud Computing has become an accessible technology which makes it possible to provide online services to end user by the network of remote servers. With the increase in remote servers and resources allocated to these remote servers leads to performance degradation of service. In such a case, the environment on which service is made run plays a significant role in order to provide better performance and adds up to Quality of Service. This paper focuses on Bare metal and Linux container environments as request response time is one of the performance metrics to determine the QOS. To improve request response time platforms are customized using real-time kernel and compiler optimization flags to optimize the performance of a service. UDP packets are served to the service made run in these customized environments. From the experiments performed, it concludes that Bare metal using real-time kernel and level 3 Compiler optimization flag gives better performance of a service.

  • 183.
    TANNEEDI, NAREN NAGA PAVAN PRITHVI
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Customer Churn Prediction Using Big Data Analytics2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

         Customer churn is always a grievous issue for the Telecom industry as customers do not hesitate to leave if they don’t find what they are looking for. They certainly want competitive pricing, value for money and above all, high quality service. Customer churning is directly related to customer satisfaction. It’s a known fact that the cost of customer acquisition is far greater than cost of customer retention, that makes retention a crucial business prototype. There is no standard model which addresses the churning issues of global telecom service providers accurately. BigData analytics with Machine Learning were found to be an efficient way for identifying churn. This thesis aims to predict customer churn using Big Data analytics, namely a J48 decision tree on a Java based benchmark tool, WEKA. Three different datasets from various sources were considered; first includes Telecom operator’s six month aggregate active and churned users’ data usage volumes, second includes globally surveyed data and third dataset comprises of individual weekly data usage analysis of 22 android customers along with their average quality, annoyance and churn scores by accompanying theses. Statistical analyses and J48 Decision trees were drawn for three different datasets. From the statistics of normalized volumes, autocorrelations were small owing to reliable confidence intervals, but confidence intervals were overlapping and close by, therefore no much significance could be noticed, henceforth no strong trends could be observed. From decision tree analytics, decision trees with 52%, 70% and 95% accuracies were achieved for three different data sources respectively.

         Data preprocessing, data normalization and feature selection have shown to be prominently influential. Monthly data volumes have not shown much decision power. Average Quality, Churn Risk and to some extent, Annoyance scores may point out a probable churner. Weekly data volumes with customer’s recent history and necessary attributes like age, gender, tenure, bill, contract, data plan, etc., are pivotal for churn prediction. 

  • 184.
    Tedla, Sukesh Kumar
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Performance Evaluation of Concurrent Multipath Transmission: Measurements and Analysis2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Context: The data transmission mechanisms in a multi-homed network has gained importance in the past few years because of its potentials. Concurrent multipath transmission (CMT) technique uses the available network interfaces for transmission by pooling multiple paths together. It allows transport mechanisms to work independent of the underlying technology, which resembles the concept of Transport Virtualization (TV). As a result, in the development of Future Internet Architectures (FIA), TV plays a vital role. The leading commercial software technologies like IOS and Android have implemented such mechanisms in their devices. Multipath TCP and CMT-SCTP are the protocols under development which support this feature. The implementation and evaluation of CMT in real-time is complex because of the challenges like path binding, out-of-order packet delivery, packet-reordering and end-to-end delay.

    Objectives: The main objective of this thesis is to identify the possibilities of implementing CMT in real-time using multiple access technologies, and to evaluate the performance of transmission by measurements and analysis under different scenarios.

    Methods: To fulfill the objectives of the thesis, different methods are adopted. The development of CMT scenario is based on a spiral methodology where each spiral refers to different objectives. The sub-stages in a spiral are mainly implementation, observations, decisions and modifications. In order to implement and identify the possibilities of CMT in real-time, a deep literature study is performed beforehand.

    Results: The throughput of data transmission is less affected by varying the total number of TCP connections in transmission. Under different cases it is observed that the throughput has significant impact by varying number of efficient paths in transmission.

    Conclusion: From the experimental methodology of this work it can be observed that, CMT can be implemented in real-time using off-the-shelf components. Based on the experimentation results, it can be concluded that the throughput of transmission is affected by increasing number of paths. It can also be concluded that the total number of TCP connections during the transmission have less impact on throughput. 

  • 185.
    Temiz, Canberk
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Challenges in Smartphone based Video QoE Assessment "In-the-Wild"2014Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [en]

    Quality of Experience (QoE) of applications is highly important sinceapoor application performance and a low QoEmay cause a user to stop using it (e.g., shift to a “better” one), or change the network operator due to misinterpretation of the underlying reason.Assessing video QoE in-the-wild is highly challenging, and the challenges have to be identified earlier to overcome and prevent any circumstances that new comers, e.g., new researchers in the area, may experience. In this thesis, a set of challenges in assessing video QoE in the wild, and user behavior during video streaming, are presented. Ultimate goal of this thesis is to provide newcomers and researchers a practical view on our conducted video QoE studies with real users in the wild. Moreover, the adapted solutions for the challenges are presented. We used a video streaming tool, VLQoE that is able to display and in parallel quantify temporal impairments. A user study consists of auser survey, face-to-face interview, and a data collection via VLQoE. In this thesis, only the results of the first two are presented and we discuss on the challenges.

  • 186.
    Thiruvallur Vangeepuram, Reventh
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Performance Comparison of Cassandra in LXC and Bare metal: Container Virtualization case study2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Big data is a developing term that describes any large amount of structured and unstructured

    data that has the potential to be mined for information. To store this type of large amounts of

    data, cloud storage systems are necessary. These cloud storage systems are developed such

    that they are capable of keeping the data accessible and available to the users over a network.

    To store big data new platforms are required. Some of the popular big data platforms are

    Mongo, Cassandra and Hadoop. In this thesis we used Cassandra database system because it

    is a distributed database and also open source. Cassandra’s architecture is master less ring

    design that is easy to setup and easy to maintain. Apache Cassandra is a highly scalable

    distributed database designed to handle big data management with linear scalable and seamless

    multiple data center deployment. It is a NoSQL database system which allow schema free

    tables so that a data item could have a variable set of columns unlike in relational databases.

    Cassandra provides with high scalability with no single point of failure.

    For the past few years’ container based virtualization has been evolving rapidly. Container

    based virtualization such as LXC have been focused here. Linux Containers (LXC) is an

    operating system level virtualization method for running multiple isolated Linux systems on a

    single control host. It does not resemble a virtual machine, but provides a virtual environment

    that has its own CPU, memory, network, etc. space and the resource control mechanism. In

    this thesis work performance of Apache Cassandra database has been analyzed between bare

    metal and Linux Containers(LXC).

    A three node Cassandra cluster has been created on both bare metal and Linux container.

    Assuming one node as seed and Cassandra stress utility tool has been used to test the load of

    Cassandra cluster. The performance of Cassandra cluster database has been evaluated in bare

    metal and Linux Container which is the goal of this thesis work.

    Linux containers (LXC) are deployed in all the servers. A three node Cassandra database

    cluster has been created in these servers and also in Linux Container(LXC). Port forwarding

    is the technique used here for making communication between Cassandra in LXC which is the

    goal of this thesis work. The performance metrics which determine the performance of

    Cassandra cluster database are selected according to it. The network configuration parameters

    are changed according to the behavior of Cassandra. By doing changes in these parameters

    Cassandra starts running according to the required configuration, after this Cassandra cluster

    performance will be analyzed. This is done with different write, read and mixed load

    operations and compared with Cassandra cluster performance on bare metal.

    The results of the thesis show an analysis of measurements of performance metrics like CPU

    utilization, Disk throughput and latency while running on Cassandra cluster in both bare metal

    and Linux Containers. A quantitative and statistical analysis of performance of Cassandra

    cluster is compared.

    The physical resources utilized by the Cassandra database on native bare metal and Linux

    Containers (LXC) is similar. According to the results, CPU utilization is more for Cassandra

    database in Linux Containers. Disk throughput is also more in Linux Containers except in the

    case of 66% load write operation. Bare metal has less latency compared to Linux Containers

    in all the scenarios.

  • 187.
    Tinashe, Kurehwaseka
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Lightweight Remote Collaboration System based on WebRTC: Improving Remote Collaboration Flexibility2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Context. Introduction of efficient multimedia technologies combined with the spreading of high-speed internet connection all over the world has led to the continuous increase in demand of multimedia services, particularly video and audio. One of the major demands are flexible, interoperable and cost-effective lightweight remote collaboration systems in companies. Web Real Time Communication (WebRTC) is an emerging peer to peer technology that is promising to be the solution to many digital real-time communication challenges. With its fantastic one-to-one communication capabilities, WebRTC supports fast and smooth audio calls, video calls, conferencing, data (media file, document and screen) sharing, gaming and all sorts of messages exchange, all being done straight out of the browser. However, as shown by investigations and interviews supported by Ericsson AB and Semcon AB as party of the MERCO (Mediated Effective Remote Collaboration) international project, many corporate use cases of remote collaboration involve applications beyond the conventional one to one communication. Present videoconferencing systems (telepresence) limits the collaboration flexibility due to their lack of the ability to adapt to system resource usage, hence tend to be too heavy for less powerful devices (laptops, tablets, phones). Moreover, their installation and maintenance costs are too expensive for small companies.  Therefore, new flexible, lightweight and less expensive solutions for remote collaboration need to be developed.

    Objectives. The main objective of this thesis is to identify technical solutions to address the challenges of resource usage flexibility in WebRTC multi-party remote collaboration systems. Despite concurrent developments of both commercial and free solutions that provide multi-party videoconferencing services using WebRTC, present solutions such as the conventional Multipoint Control Unit (MCU), Selective Forwarding Unit (SFU) and Fully Meshed architectures suffers from issues of excessive resource usage and cannot deliver the acceptable quality of experience in different use cases, particularly the mobile environment. The aim of this thesis is to investigate lightweight technical solutions that can be used to improve the system resource usage in WebRTC multiparty conferencing systems. Through understanding the architectural designs, benchmarking the performance of various technologies used in WebRTC and selecting the most suitable techniques a prototype is developed as a proof of concept.

    Methods. The first part of the thesis is dedicated to comprehensive study of fundamentals, background information and related works on WebRTC. This gives knowledge of technologies, techniques and performance evaluation metrics which help in making appropriate technical decisions during the experimental development of WebRTC solutions. The second part of the thesis is dedicated to experimental investigation in which two WebRTC signaling technologies (XSockets and NodeJs) are evaluated based on call setup time in WebRTC group call. Two lightweight technical solutions for improving resource usage flexibility (Switching video quality based on speech and using emotions and gestures instead of video) are evaluated based on system resources (CPU, memory, disk and network) and user experience.

    Results. Based on call setup time of WebRTC multi-party calls, the experimental results indicates that XSockets is a better signaling technology than NodeJs. The two proposed lightweight solutions have shown a remarkable improvement based on systems resource usage. A 15% reduction of CPU usage is observed when using speech controlled video quality switching and further 10% reduction is observed when video is replaced by emotions and gestures.

    Conclusions. Despite the minimal resource usage achieved by using emotions technique, this solution has usability issues as it cannot detect emotions in poor lighting environment. Consequently, the solution of switching video quality based on speech is chosen for further implementation. Though, this technique can be further improved through using machine learning techniques, the current implementation can significantly reduce the amount CPU, memory, disk and network usage to allow up to 6 participants to join a single conference call while maintain acceptable quality of experience.

  • 188.
    Tipirisetty, Venkat Sivendra
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Performance Analysis of Service in Heterogeneous Operational Environments2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In recent years there is a rapid increase in demand for cloud services, as cloud computing has become a flexible platform for hosting microservices over the Internet. Microservices are the core elements of service oriented architecture (SOA) that facilitate the deployment of distributed software systems. As the user requires good quality of service the response time of microservices is critical in assessing the performance of the application from the end user perspective.This thesis work aims at developing a typical service architecture to facilitate the deployment of compute and I/O intensive services. The work also aims at evaluating the service times of these service when their respective subservices are deployed in heterogeneous environments with various loads.The research work has been carried out using an experimental testbed in order to evaluate the performance. The transport level performance metric called Response time is measured. It is the time taken by the server to serve the request sent by the client. Experiments have been conducted based on the objectives that are to be achieved.The results obtained from the experimentation contain the average service times of a service when it is deployed on both virtual and non-virtual environment. The virtual environment is provided by Docker containers. They also include the variation in position of their subservices. From results it can be concluded that the total service times obtained are less in case of non-virtual environments when compared to container environment.

  • 189.
    Tran, Hung
    et al.
    Mälardalens högskola, SWE.
    Kaddoum, Georges
    Universite du Quebec a Montreal, CAN.
    Gagnon, Francois
    Universite du Quebec a Montreal, CAN.
    Sibomana, Louis
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Cognitive radio network with secrecy and interference constraints2017In: Physical Communication, ISSN 1874-4907, Vol. 22, p. 32-41Article in journal (Refereed)
    Abstract [en]

    In this paper, we investigate the physical-layer security of a secure communication in single-input multiple-output (SIMO) cognitive radio networks (CRNs) in the presence of two eavesdroppers. In particular, both primary user (PU) and secondary user (SU) share the same spectrum, but they face with different eavesdroppers who are equipped with multiple antennas. In order to protect the PU communication from the interference of the SU and the risks of eavesdropping, the SU must have a reasonable adaptive transmission power which is set on the basis of channel state information, interference and security constraints of the PU. Accordingly, an upper bound and lower bound for the SU transmission power are derived. Furthermore, a power allocation policy, which is calculated on the convex combination of the upper and lower bound of the SU transmission power, is proposed. On this basis, we investigate the impact of the PU transmission power and channel mean gains on the security and system performance of the SU. Closed-form expressions for the outage probability, probability of non-zero secrecy capacity, and secrecy outage probability are obtained. Interestingly, our results show that the strong channel mean gain of the PU transmitter to the PU's eavesdropper in the primary network can enhance the SU performance.

  • 190.
    Tran, Hung
    et al.
    Malardalen Univ, S-72123 Vasteras, Sweden..
    Zepernick, Hans-Juergen
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems. Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems. Blekinge Institute of Technology, School of Engineering, Department of Signal Processing. Blekinge Institute of Technology, School of Computing. Blekinge Institute of Technology, School of Engineering, Department of Electrical Engineering.
    Phan, Hoc
    Univ Reading, Reading RG6 6AY, Berks, England..
    On Throughput and Quality of Experience in Cognitive Radio Networks2016In: 2016 IEEE WIRELESS COMMUNICATIONS AND NETWORKING CONFERENCE, IEEE , 2016Conference paper (Refereed)
    Abstract [en]

    In this paper, a performance analysis for cognitive radio networks (CRNs) under the outage probability constraint of the primary user and peak transmit power constraint of the secondary user is conducted. Given an automatic repeat request protocol, analytical expressions for the packet delay and throughput of the CRN are derived. Most importantly, these expressions can be used to understand the quality of experience on web services which are assumed to be offered by the considered CRN.

  • 191.
    Tran, Hung
    et al.
    Malardalen Univ, SWE.
    Zepernick, Hans-Jürgen
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Proactive Attack: A Strategy for Legitimate Eavesdropping2016In: 2016 IEEE Sixth International Conference on Communications and Electronics (ICCE), IEEE, 2016, p. 457-461Conference paper (Refereed)
  • 192.
    Tran, Hung
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Zepernick, Hans-Jürgen
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Phan, Hoc
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Sibomana, Louis
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Performance Analysis of a Cognitive Radio Network with a Buffered Relay2015In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 64, no 2, p. 566-579Article in journal (Refereed)
    Abstract [en]

    In this paper, we analyze the packet transmission time in a cognitive cooperative radio network (CCRN) where a secondary transmitter (SU-Tx) sends packets to a secondary receiver (SU-Rx) through the help of a secondary relay (SR). In particular, we assume that the SU-Tx and SR are subject to the joint constraint of the timeout probability of the primary user (PU) and the peak transmit powers of the secondary users. On this basis, we investigate the impact of the transmit power of the PUs and channel mean powers on the packet transmission time of the CCRN. Utilizing the concept of timeout, adaptive transmit power allocation policies for the SU-Tx and SR are considered. More importantly, analytical expressions for the endto- end throughput, end-to-end packet transmission time, and stable condition for the SR operation are obtained. Our results indicate that the second hop of the considered CCRN is not a bottleneck if the channel mean powers of the interference links of the networks are small and the SR peak transmit power is set to a high value.

  • 193.
    Tran, Hung
    et al.
    Mälardalen University, SWE.
    Zepernick, Hans-Jürgen
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Sibomana, Louis
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Performance of cognitive radio networks under interference constraints of multiple primary users2016In: 2016, 10th International Conference on Signal Processing and Communication Systems, ICSPCS 2016 - Proceedings, IEEE, 2016Conference paper (Refereed)
    Abstract [en]

    In this paper, we study the performance of point-to-point communication in spectrum sharing systems under the peak interference power constraint of multiple primary users. In particular, we assume that the channels undergo independent but not necessarily identically distributed Nakagami-m fading with integer values of fading severity parameter m. The cumulative distribution function and probability density function for the signal-to-noise ratio are derived. Based on these formulas, we obtain analytical expressions for the outage probability, the ergodic capacity, and the symbol error probability. Numerical results are also provided to investigate the impact of the peak interference power-to-noise ratio, the number of primary users, and fading parameters on the performance of the secondary network. © 2016 IEEE.

  • 194.
    Tutschku, Kurt
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Ahmadi Mehri, Vida
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Carlsson, Anders
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Chivukula, Krishna Varaynya
    CityNetwork Webbhotell AB.
    Johan, Christenson
    CityNetwork Webbhotell AB.
    On Resource Description Capabilities of On-Board Tools for Resource Management in Cloud Networking and NFV Infrastructures2016In: 2016 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS WORKSHOPS (ICC), 2016, p. 442-447Conference paper (Refereed)
    Abstract [en]

    The rapid adoption of networks that are based on "cloudification" and Network Function Virtualisation (NFV) comes from the anticipated high cost savings of up to 70% in their build and operation. The high savings are founded in the use of general standard servers, instead of single-purpose hardware, and by efficiency resource sharing through virtualisation concepts. In this paper, we discuss the capabilities of resource description of "on-board" tools, i.e. using standard Linux commands, to enable OPEX savings. We put a focus on monitoring resources on small time-scales and on the variation observed on such scales. We introduce a QoE-based comparative concept that relates guest and host views on "utilisation" and "load" for the analysis of the variations. We describe the order of variations in "utilisation" and "load" by measurement and by graphical analysis of the measurements. We do these evaluations for different host operating systems and monitoring tools.

  • 195.
    Tutschku, Kurt Tutschku
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Ahmadi Mehri, Vida
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Carlsson, Anders
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Towards Multi-layer Resource Management in Cloud Networking and NFV Infrastructures2016Conference paper (Refereed)
    Abstract [en]

    Cloud Networking (CN) and related conceptsoffer appealing novelties to Cloud Computing (CC) customers.They can do a one-stop-shopping for network-enhanced cloudservices. In addition, the costs of such services might below due to multiple customers sharing the infrastructures.Moreover, telecommunication network operators are adopt-ing the CN in theirNetwork Functions Virtualisation (NFV)framework for reducing costs and increasing the flexibility oftheir networks. The technical appeal of CN comes from thetight integration of CC and smart networks. The economicalattractiveness results from avoiding dedicated hardware, shar-ing of resources, and simplified resource management (RM) asseen by the users respectively by the applications. The visionof cheap and integrated CN services is obviously attractive,but it is also evident that it will require more complex RMprocedures for efficiently balancing the usage of all resources.In this contribution, we suggest an initial architecture forintegrated and practical RM in CN and NFV systems. TheRM concept aims at locating and analysing performancebottlenecks, efficiency problems, and eventually discover un-used resources. The suggested architecture is based on alayered view on the system. Moreover, we detail difficultiesin practical resources usage monitoring which, in turn, definerequirements for a RM architecture. The requirement analysisis based on measurements in a CN infrastructure.

  • 196.
    UMESH, AKELLA
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Performance analysis of transmission protocols for H.265 encoder2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In recent years there has been a predominant increase in multimedia services such as live streaming, Video on Demand (VoD), video conferencing, videos for the learning. Streaming of high quality videos has become a challenge for service providers to enhance the user’s watching experience. The service providers cannot guarantee the perceived quality. In order to enhance the user’s expectations, it is also important to estimate the quality of video perceived by the user. There are different video streaming protocols that are used to stream from server to client. In this research, we aren’t focused on the user’s experience. We are mainly focused on the performance behavior of the protocols.

    In this study, we investigate the performance of the HTTP, RTSP and WebRTC protocols when streaming is carried out for H.265 encoder. The study addresses for the objective assessment of different protocols over VoD streaming at the network and application layers. Packet loss and delay variations are altered at the network layer using network emulator NetEm when streaming from server to client. The metrics at the network layer and application layer are collected and analyzed. The video is streamed from server to a client, the quality of the video is checked by some of the users.

    The research method has been carried out using an experimental testbed. The metrics such as packet counts at network layer and stream bitrate at application layer are collected for HTTP, RTSP and WebRTC protocols. Variable delays and packet losses are injected into the network to emulate real world.

    Based on the results obtained, it was found at the application layer that, out of the three protocols, HTTP, RTSP and WebRTC, the stream bitrate of the video transmitted using HTTP was less when compared to the other. Hence, HTTP performs better in the application layer. At the network layer, the packet counts of the video transmitted were collected using TCP port for HTTP and UDP port for RTSP and WebRTC protocols. The performance of HTTP was found to be stable in most of the scenarios. On comparing RTSP and WebRTC, the number of packet counts collected were more in number for RTSP when compared to WebRTC. This is because, the protocol and also the streamer are using more resources to transmit the video. Hence, both the protocols RTSP and WebRTC are performing better relatively. 

  • 197.
    Uppalapati, Navya
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Optimizing Energy Consumption Using Live Migration2016Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Context: Cloud Computing has evolved and advanced over the recent years due to its concept of sharing computing resources rather than having local servers to handle applications. The growth of Cloud Computing has resulted in large number of datacenters around the world containing thousands of nodes. The nodes are used to process various forms of workloads. Generally, the datacenters efficiency is calculated solely based how fast workload can be processed. Recently, energy consumption has been adopted as additional efficiency metric. The main reasons for this development is increased environmental awareness and escalating costs related to supplying power to large number units and to datacenter cooling. Cloud providers has developed the concept of virtualization, where multiple operating system and applications run on the same server at the same time. A key feature enabled by virtualization is migrating a virtual machine from one physical host to another. In particular, the capability of Virtual Machine (VM) migration brings multiple benefits such elastic resource sharing and energy aware consolidation. Live Virtual Machine migration in datacenters has great potential to decrease energy consumption up to certain level of usage.

    Objectives: The aim of this thesis is to perform cold and/or live migration to relocate Virtual Machines among hosts in a datacenter thereby reducing the energy consumption. PowerAPI is used to estimate the energy consumption of each VM. A heuristic algorithm is developed and evaluated in order to optimize energy consumption. The overall CPU utilization is calculated during the live migration when the energy consumed is optimized.

    Method: With the obtained knowledge about the VM migration and the factors that influence the migration process, a heuristic algorithm is designed for limiting energy consumption in datacenter. The algorithm takes the energy distribution over a set of VMs and corresponding hosts as input. The output of this algorithm will be the redistribution of VMs to the hosts such that the overall energy consumption is lowered. The proposed model is implemented and evaluated in an Openstack environment.

    Results: The results of the experiment study give the energy consumption of each node and then sumup to give the total energy consumption of the datacenter. The results are taken with the default OpenStack VM placement algorithm as well as with the heuristic algorithm developed in this work. The comparison of results indicate that the total energy consumption of the datacenter is reduced when the heuristic is used. The overall CPU utilization of each node is evaluated and the values are almost similar when compared with heuristic.

    Conclusion: The analysis of results concludes that the overall energy consumption of the datacenter is optimized by relocating the virtual machines among hosts according to the algorithm using virtual machine live migration. This also results that CPU Utilization is not varied much when live migration is used to optimize the energy consumption.

  • 198.
    Vemula, S Sai Srinivas Jayapala
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems. Blekinge Institute of Technology.
    Performance Evaluation of OpenStack Deployment Tools2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Cloud computing allows access to a collection of computing resources that can be easily provisioned, configured as well as released on-demand with minimum cost and effort. OpenStack is an open source cloud management platform aimed at providing public or private IaaS cloud on standard hardware. Since, deploying OpenStack manually is tedious and time-consuming, several tools that automate the deployment of OpenStack are available. Usually, cloud administrators choose a tool based on its level of automation, ease of use or interoperability with existing tools used by them. However, another desired factor while choosing a deployment tool is its deployment speed. Cloud admins cannot select based on this factor since, there is no previous work done on the comparison of deployment tools based on deployment time. This thesis aims to address this issue.

    The main aim of the thesis is to evaluate the performance of OpenStack deployment tools with respect to operating system provisioning and OpenStack deployment time, on physical servers. Furthermore, the effect of varying number of nodes, OpenStack architecture deployed and resources (cores and RAM) provided to deployment node on provisioning and deployment times, is also analyzed. Also, the tools are classified based on stages of deployment and method of deploying OpenStack services. In this thesis we evaluate the performance of MAAS, Foreman, Mirantis Fuel and Canonical Autopilot.

    The performance of the tools is measured via experimental research method. Operating system provisioning time and OpenStack deployment times are measured while varying the number of nodes/ OpenStack architecture and resources provided to deployment node i.e. cores and RAM.

    Results show that provisioning time of MAAS is less than Mirantis Fuel which is less than Foreman for all node scenarios and resources cases considered. Furthermore, for all 3 tools as number of nodes increases provisioning time increases. However, the amount of increase is lowest for MAAS than Mirantis Fuel and Foreman. Similarly, results for bare metal OpenStack deployment time show that, Canonical Autopilot outperforms Mirantis Fuel by a significant difference for all OpenStack scenarios and resources cases considered. Furthermore, as number of nodes in an OpenStack scenario as well as its complexity increases, the deployment time for both the tools increases.

    From the research, it is concluded that MAAS and Canonical Autopilot perform better as provisioning and bare metal OpenStack deployment tool respectively, than other tools that have been analyzed. Furthermore, from the analysis it can be concluded that increase in number of nodes/ OpenStack architecture, leads to an increase in both provisioning time and OpenStack deployment time for all the tools. Finally, after analyzing the results the tools are classified based on the method of deploying OpenStack services i.e. parallel or role-wise parallel.

  • 199.
    Vemulapalli, Revanth
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Mada, Ravi Kumar
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Performance of Disk I/O operations during the Live Migration of a Virtual Machine over WAN2014Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Virtualization is a technique that allows several virtual machines (VMs) to run on a single physical machine (PM) by adding a virtualization layer above the physical host's hardware. Many virtualization products allow a VM be migrated from one PM to other PM without interrupting the services running on the VM. This is called live migration and offers many potential advantages like server consolidation, reduced energy consumption, disaster recovery, reliability, and efficient workflows such as "Follow-the-Sun''. At present, the advantages of VM live migration are limited to Local Area Networks (LANs) as migrations over Wide Area Networks (WAN) offer lower performance due to IP address changes in the migrating VMs and also due to large network latency. For scenarios which require migrations, shared storage solutions like iSCSI (block storage) and NFS (file storage) are used to store the VM's disk to avoid the high latencies associated with disk state migration when private storage is used. When using iSCSI or NFS, all the disk I/O operations generated by the VM are encapsulated and carried to the shared storage over the IP network. The underlying latency in WAN will effect the performance of application requesting the disk I/O from the VM. In this thesis our objective was to determine the performance of shared and private storage when VMs are live migrated in networks with high latency, with WANs as the typical case. To achieve this objective, we used Iometer, a disk benchmarking tool, to investigate the I/O performance of iSCSI and NFS when used as shared storage for live migrating Xen VMs over emulated WANs. In addition, we have configured the Distributed Replicated Block Device (DRBD) system to provide private storage for our VMs through incremental disk replication. Then, we have studied the I/O performance of the private storage solution in the context of live disk migration and compared it to the performance of shared storage based on iSCSI and NFS. The results from our testbed indicate that the DRBD-based solution should be preferred over the considered shared storage solutions because DRBD consumed less network bandwidth and has a lower maximum I/O response time.

  • 200.
    Venigalla, Thejaswi
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Akkapaka, Raj Kiran
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Teletraffic Models for Mobile Network Connectivity.2013Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    We are in an era marked by tremendous global growth in mobile traffic and subscribers due to change in the mobile communication technology from second generation to third and fourth generations. Especially usage of packet-data applications has recorded remarkable growth. The need for mobile communication networks capable of providing an ever increasing spectrum of services calls for efficient techniques for the analysis, monitoring and design of networks. To meet the ever increasing demands of the user and to ensure on reliability and affordability, system models that can capture the characteristics of actual network load and yield acceptable precise predictions of performance in a reasonable amount of time must be developed. This can be achieved using teletraffic models as they capture the behaviour of system through interpret-able functions and parameters. Past years have seen extremely numerous teletraffic models for different purposes. Nevertheless there is no model that provides a proper frame work to analyse the mobile networks. This report attempts to provide a frame work to analyse the mobile traffic and based on the analysis we design teletraffic models that represent the realistic mobile networks and calculate the buffer under-flow probability.

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