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  • 51.
    Amjad, Shoaib
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Malhi, Rohail Khan
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Burhan, Muhammad
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    DIFFERENTIAL CODE SHIFTED REFERENCE IMPULSE-BASED COOPERATIVE UWB COMMUNICATION SYSTEM2013Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    Cooperative Impulse Response – Ultra Wideband (IR-UWB) communication is a radio technology very popular for short range communication systems as it enables single-antenna mobiles in a multi-user environment to share their antennas by creating virtual MIMO to achieve transmit diversity. In order to improve the cooperative IR-UWB system performance, we are going to use Differential Code Shifted Reference (DCSR). The simulations are used to compute Bit Error Rate (BER) of DCSR in cooperative IR-UWB system using different numbers of Decode and Forward relays while changing the distance between the source node and destination nodes. The results suggest that when compared to Code Shifted Reference (CSR) cooperative IR-UWB communication system; the DCSR cooperative IR-UWB communication system performs better in terms of BER, power efficiency and channel capacity. The simulations are performed for both non-line of sight (N-LOS) and line of sight (LOS) conditions and the results confirm that system has better performance under LOS channel environment. The simulation results also show that performance improves as we increase the number of relay nodes to a sufficiently large number.

  • 52.
    AMUJALA, NARAYANA KAILASH
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    SANKI, JOHN KENNEDY
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Video Quality of Experience through Emulated Mobile Channels2014Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    Over the past few years, Internet traffic took a ramp increase. Of which, most of the traffic is video traffic. With the latest Cisco forecast it is estimated that, by 2017 online video will be highly adopted service with large customer base. As the networks are being increasingly ubiquitous, applications are turning equally intelligent. A typical video communication chain involves transmission of encoded raw video frames with subsequent decoding at the receiver side. One such intelligent codec that is gaining large research attention is H.264/SVC, which can adapt dynamically to the end device configurations and network conditions. With such a bandwidth hungry, video communications running over lossy mobile networks, its extremely important to quantify the end user acceptability. This work primarily investigates the problems at player user interface level compared to the physical layer disturbances. We have chosen Inter frame time at the Application layer level to quantify the user experience (player UI) for varying lower layer metrics like noise and link power with nice demonstrator telling cases. The results show that extreme noise and low link level settings have adverse effect on user experience in temporal dimension. The video are effected with frequent jumps and freezes.

  • 53.
    ananth, Indirajith Vijai
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Study on Assessing QoE of 3DTV Using Subjective Methods2013Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    The ever increasing popularity and enormous growth in 3D movie industry is the stimulating phenomenon for the penetration of 3D services into home entertainment systems. Providing a third dimension gives intense visual experience to the viewers. Being a new eld, there are several researches going on to measure the end user's viewing experience. Research groups including 3D TV manufacturers, service providers and standards organizations are interested to improve user experience. Recent research in 3D video quality measurements have revealed uncertain issues as well as more well known results. Measuring the perceptual stereoscopic video quality by subjective testing can provide practical results. This thesis studies and investigate three di erent rating scales (Video Quality, Visual Discomfort and Sense of Presence) and compares them by subjective testing, combined with two viewing distances at 3H and 5H, where H is the hight of display screen. This thesis work shows that single rating scale produces the same result as three di erent scales and viewing distance has very less or no impact on Quality of Experience (QoE) of 3DTV for 3H and 5H distances for symmetric coding impairments.

  • 54.
    Ande, Rama kanth
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Amarawadi, Sharath Chandra
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Evaluation of ROS and Arduino Controllers for the OBDH Subsystem of a CubeSat2012Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [sv]

    One of the future trend setting research areas in CubeSat projects is the implementation of ROS in CubeSat. Robot Operating System (ROS) is aiming to capture the future of many embedded systems including Robotics. In this thesis, an attempt is made to understand the challenges faced during implementing ROS in CubeSat to provide a foundation for the OBDH subsystem and provide important guidelines for future developers relying on ROS run CubeSats. Since using traditional transceivers and power supply would be expensive, we have tried simulating Arduino to act as transceiver and power supply subsystems. Arduino is an open-source physical computing platform based on a simple microcontroller board, and a development environment for writing software for the board designed to make the process of using electronics in major embedded projects more accessible and inexpensive.

  • 55.
    Andersson, Eskil
    et al.
    Blekinge Tekniska Högskola, Institutionen för arbetsvetenskap och medieteknik.
    Akrawi, Sirvan
    Blekinge Tekniska Högskola, Institutionen för arbetsvetenskap och medieteknik.
    CU2: Design av ett PDA-baserat diskussionverktyg med ljud/bildkommunikation2001Självständigt arbete på avancerad nivå (magisterexamen)Studentuppsats (Examensarbete)
    Abstract [sv]

    I detta arbete framlägger vi ett designförslag på hur ett diskussionsverktyg som stödjer ljud- och bildkommunikation kan se ut. Ett förslag som förbättrar och förenklar den distanskommunikation som idag sker med hjälp av mobiltelefoner, videokonferenssystem samt webbkameror anslutna till persondatorer. Den design vi föreslår möjliggör för mobila användare att visuellt föra flerpartssamtal med hjälp av PDA:er. Vårt designförslag har fått arbetsnamnet CU2 (see you too) och är tänkt att fungera i tredje och/eller fjärde generationens mobila nät. Vi har valt att genomföra vårt magisterarbete på företaget A Brand New World i Kista, Stockholm. Företaget utvecklar och säljer system inom mobilt Internet.

  • 56.
    Andersson, Roger
    et al.
    Blekinge Tekniska Högskola, Institutionen för telekommunikation och signalbehandling.
    Sjölander, Torbjörn
    Blekinge Tekniska Högskola, Institutionen för telekommunikation och signalbehandling.
    Forming a common addressing algorithm for digital CAS register signalling1998Självständigt arbete på grundnivå (kandidatexamen)Studentuppsats (Examensarbete)
    Abstract [sv]

    Syftet med detta examensarbetet var att undersöka möjligheterna att skapa en gemensam adresseringsalgoritm för de digitala CAS trunkprogrammen som används vid uppkoppling av utgående samtal i en växel. Adresseringsalgoritmen är beskriven med SDL-flödesschema och i programspråket PLEX-M. Resultatet av examensarbetet blev att adresseringsbiten i några av trunkprogrammen ersattes med den gemensamma algoritmen och framgångsrikt verifierades i MD-labbet. Mängden kod minskade i alla de trunkprogram som testades.

  • 57. Angelin, Lars
    On the Properties of a Congestion Control Mechanism for Signaling Networks Based on a State Machine1996Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Congestion control in signaling systems is a necessity to fulfil the requirements of a tele-communication network that aims satisfy the customers’ requirements on service quality. Heavy network load is an important source of customer dissatisfaction as congested net-works result in deteriorated service quality. Sessions of a signaling service with high real time demands which are subject to unacceptable delays may be obsolete or prematurely terminated by the customer; in either way, they are a burden to the signaling network. It would ease the load of the network and improve the performance of all sessions in progress, if such delayed sessions could be aborted as quickly as possible. By measuring the network delay on individual signals of a service session, it is possible to perform signaling network congestion control that considers the state in the entire signaling network. Under the assumption that a session comprises a sequence of signals between one originating node and an arbitrary number of destination nodes, it is possible to predict the total duration of a session. The prediction is calculated from previously completed signals using a state machine, which is defined per signaling link. The annihilation of sessions, for which the prediction exceeds a predefined time limit, is an embryo of a simple signaling network congestion control mechanism (CCM). This simple CCM increases the number of successfully completed services with several hundred percent under favorable circum-stances. The state machine approach is proven to perform well in all types of environ-ments. The robustness and stability of the proposed CCM is demonstrated in a wide range of environments. The fairness in the admission of signaling services into the network at very high loads are also shown to be good.

  • 58. Angelin, Lars
    et al.
    Arvidsson, Åke
    A Congestion Control Algorithm for Signalling Networks Based on a State Machine Controlled by Network Delays1995Konferensbidrag (Refereegranskat)
    Abstract [en]

    Congestion control in Signaling System number 7 faces new challenges as mobile com-munication systems and Intelligent Networks grow rapidly. New services change traffic patterns, add to signalling network load, and raise demands on shorter service completion times. To handle new demands, the congestion control mechanisms must foresee an over-load situation, and respond to it so that the network can maintain high throughput. With the introduction of a state machine and a memory function for each signaling link it is possible to predict the completion time of a service session and to detect an emerging congestion. If the predicted completion time of a service session is too long, the session is annihilated. This is the foundation of a congestion control mechanism that reacts fast on information supplied by the network. The congestion control mechanism enables the network to main-tain a high throughput during overload.

  • 59. Angelin, Lars
    et al.
    Arvidsson, Åke
    A Congestion Control Mechanism for Signaling Networks based on Network Delays1995Konferensbidrag (Refereegranskat)
    Abstract [en]

    Congestion control in Signaling System #7 faces new challenges as mo-bile communication systems and Intelligent Networks grow rapidly. New ser-vices change traffic patterns, add to signalling network load, and raise demands on shorter service completion times. To handle new demands, the congestion control mechanisms must foresee an overload situation, and respond to it so that the network can maintain high probability for successful service comple-tion. With the introduction of a state machine and a memory function for each signaling link it is possible to predict the completion time of a service session and to detect an emerging congestion. If the predicted completion time of a service session is too long, the session is annihilated. This is the foundation of a congestion control mechanism that reacts fast on information supplied by the congested part of the network. The congestion control mechanism increases the ratio of successfully completed service sessions during congestion by several hundred percent.

  • 60. Angelin, Lars
    et al.
    Arvidsson, Åke
    On the Robustness of a Congestion Control Algorithm for Signaling Networks Based on a State Machine1996Konferensbidrag (Refereegranskat)
    Abstract [en]

    Sessions of a signaling service with high real time demands which are subject to unaccept-able delays may be obsolete or prematurely terminated by the customer; in either way, they are a burden to the signaling network. It would ease the load of the network and im-prove the performance of all sessions in progress, if such delayed sessions could be abort-ed as quickly as possible. By measuring the network delay on individual signals of a service session, it is possible to perform signaling network congestion control that consid-ers the state in the entire signaling network. Under the assumption that a session comprises a sequence of signals between one originating node and an arbitrary number of destination nodes, it is possible to predict the total duration of a session. The prediction is calculated from previously completed signals using a state machine, which is defined per signaling link. The annihilation of sessions, for which the prediction exceeds a predefined time limit, is an embryo of a simple signaling network congestion control mechanism (CCM). This simple CCM increases the number of successfully completed services with a few hundred percent under favorable circumstances. The state machine approach has been proven to function well in all types of environments. The robustness and stability of the proposed CCM is demonstrated and the fairness in the admission of signaling services into the net-work at very high loads are also shown.

  • 61. Angelin, Lars
    et al.
    Pettersson, Stefan
    Arvidsson, Åke
    A Network Approach to Signalling Network Congestion Control1995Konferensbidrag (Refereegranskat)
    Abstract [en]

    Congestion control in Signaling System #7 faces new challenges as mobile communication systems and Intelligent Networks grow rapidly. New services change traffic patterns, add to signalling network load, and raise demands on shorter service completion times. To handle new demands, the congestion control mechanisms must foresee an overload situation, and respond to it so that the net-work can maintain high probability for successful service completion. By measur-ing the time consumption for the initial Message Signalling Units of a service session it is possible to predict the duration of the service session and to detect an emerging congestion. If the predicted duration of the service session is too long, the service session is annihilated. This is the foundation of a congestion control mechanism that reacts fast and on information supplied by the congested part of the network. The congestion control mechanism increases the ratio of successfully completed services during congestion by several hundred percent.

  • 62.
    Ansere, James Adu
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap.
    Ehimiaghe, Odion
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap.
    APPLYING DISTRIBUTED ORTHOGONAL SPACE TIME BLOCK CODING IN COOPERATIVE COMMUNICATION NETWORKS2012Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    In this research, we investigate cooperative spectrum sensing using distributed orthogonal space time block coding (DOSTBC). Multiple antennas are introduced at the transmitter and the receiver to achieve higher cooperative diversity in the cooperative wireless (CW) networks. The received signals from the primary users (PUs) at the cooperative relays (CRs) are encoded and retransmitted to the cooperative controller (CC), where further decisions are made depending on the information sent from the CRs. The cooperative relaying protocol employed here in CRs is based on decoding forward (DF) technique. The proposed Alamouti scheme in orthogonal space time block code (OSTBC) has been found to enhance detection performance in CW networks. The analyses over independent Rayleigh fading channels are performed by the energy detector. In CW networks the secondary users (SUs) use the available frequency band as the PUs is absent. The SU discontinue using the licensed band and head off as soon as the PU is present. The SUs is more responsive and intelligent in detecting the spectrum holes. The principal aim of the CW network is to use the available holes without causing any interference to the PUs. The CRs are preferably placed close to the PU to detect transmitted signal, with decoding capability the information collected are decoded by CRs using Maximum Likelihood (ML) decoding technique. The CRs then re-encode the decoded data and retransmit it to the receiver. The energy detector accumulates information from various users, compares it using threshold value (T_f) predefined and the final decision made. The probabilities of detection and false alarm are observed using DOSTBC on PU and SU in cooperative communication via DF protocol. The system performance is investigated with single and multiple relays; with and without direct path between the PUs and SUs. Selection Combining (SC) and Maximum Ratio Combining (MRC) schemes are applied in energy detector and the outcomes are evaluated with and without direct link between PU and SU. The proposed cooperative spectrum sensing using DF protocol at CRs with Alamouti space time block code (STBC) is processed and results are validated by computer simulation.

  • 63.
    Anwar, Khurshid
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Khan, Asad
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    AC and QAR for Provisioning of QoS in MANETs2010Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [sv]

    The literature study shows that the performance of network layer best-effort protocols has been improved with the use of QAR and AC protocols to sustain the QoS requirements of the applications. In current literature AC and QAR protocols are satisfying single metric of QoS. At the same time different applications such as multimedia applications which require various types of assurance from the network on the Quality of services (QoS) The simulation results show that DSR performance is better than AODV when we have less traffic load.

  • 64. Apell, Maria
    et al.
    Erman, David
    Popescu, Adrian
    Testbed for Advanced Mobile Solutions2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper describes the implementation of an IMS testbed, based on open source technologies and operating systems. The testbed provides rich communication services, i.e., Instant Messaging, Network Address Book and Presence as well as VoIP and PSTN interconnectivity. Our validation tests indicate that the performance of the testbed is comparable to similar testbeds, but that operating system virtualization signi ficantly aff ects signalling delays.

  • 65.
    Appana, Dileep Kumar
    et al.
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Kumar, Chinni Anil
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Nagappan, Nagappan Palaniappan
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Channel Estimation in GPRS based Communication System using Bayesian Demodulation.2009Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    With the increase use of portable devices such as Personal Digital Assistants (PDA), laptops, voice and data integrated cell phones and many more, there is a need of wireless communication method using air as the medium to transmit and receive information between terminals. Radio waves propagate from transmitting antenna and travel through free space undergoing reflections, diffractions and scattering. They are greatly affected by ground terrain, the atmosphere and the objects in their path like buildings, bridges, hills etc. Nowadays, the existence of a direct line of sight path between the transmitter and the receiver is unlikely. These multiple phenomena are responsible for most of the characteristic features like the quality of the received signal. In the above case propagation is mainly due to reflection and cattering from the buildings and by diffraction. So, in practice the transmitted signal arrives at the receiver via several paths with different time delays creating a multi path situation at the receiver, these multipath waves with randomly distributed amplitudes and phases combine to give a resultant signal that fluctuates in time and space. This phenomenon of random fluctuations in received signal level is termed as fading. The existing demodulation techniques like FM, AM will determine the signal from the received signal based on the mean distance method, which cannot provide the desired level of BER, which fails in proper estimation under high fading and high Doppler-Shift effect. SOLUTION: This project provides the implementation of an enhancement to the demodulation technique using Bayesian approach for the physical layer simulation of a General Packet Radio System (GPRS) considering variable Rician fading and variable Doppler-Shift effect for an AWGN channel. The system performance is evaluated based on Bit Error Rate (BER) and Signal to Noise Ratio (SNR) for the realized GPRS system. Matlab platform is used for the implementation, analysis of the proposed system with for functional verification in terms of BER and SNR. We have showed the comparative difference between the theoretical calculation of QPSK signal and to the values obtained by our program. The values show difference up to 0.4 db for a 1000 bit random vector. Moreover, we also compared with QAM demodulation technique in MATLAB code to show difference up to 1.4 db for a 1000 bit vector. These results signify better performance of the system as it has saved bandwidth.

  • 66.
    Appuni, Bala Satish
    et al.
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Vemasani, Vamsi Krishna
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Performance Evaluation of Power Control Algorithms in Cellular Radio Communication Systems2004Självständigt arbete på avancerad nivå (magisterexamen)Studentuppsats (Examensarbete)
    Abstract [sv]

    In cellular radio communication systems, there are large variations in signal strength due to Rayleigh fading radio channel and interference, which there by reduces the overall efficiency of the system. In order to mitigate these effects, Power control is highly needed. Power control is an effective approach to reduce the interference and increase the system capacity and also achieves different quality of service requirements. In the upcoming days, there is a high need for QOS requirements and efficient radio management. Since PC deals with both these areas, it is worthy enough to look into these research areas and make a significant contribution in these areas.

  • 67. Arkoulis, Stamatios
    et al.
    Marias, Giannis
    Frangoudis, Pantelis
    Oberender, Jens
    Popescu, Alexandru
    Fiedler, Markus
    Meer, Hermann de
    Polyzos, George
    Misbehaviour Scenarios in Cognitive Radio Networks2010Ingår i: Future Internet, ISSN 1999-5903, E-ISSN 1999-5903, Vol. 2, nr 3-4, s. 212-237Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Recent advances in the fields of Cognitive Radio and the proliferation of open spectrum access promise that spectrum-agile wireless communication will be widespread in the near future, and will bring significant flexibility and potential utility improvements for end users. With spectrum efficiency being a key objective, most relevant research focuses on smart coexistence mechanisms. However, wireless nodes may behave selfishly and should be considered as rational autonomous entities. Selfishness, pure malice or even faulty equipment can lead to behavior that does not conform to sharing protocols and etiquette. Thus, there is a need to secure spectrum sharing mechanisms against attacks in the various phases of the sharing process. Identifying these attacks and possible countermeasures is the focus of this work.

  • 68. Arlos, Patrik
    Application Level Measurement2011Ingår i: Network Performance Engineering: A Handbook on Convergent Multi-Service Networks and Next Generation Internet, Berlin / Heidelberg: Springer , 2011, s. 14-36Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    In some cases, application-level measurements can be the only way for an application to get an understanding about the performance offered by the underlying network(s). It can also be that an application-level measurement is the only practical solution to verify the availability of a particular service. Hence, as more and more applications perform measurements of various networks; be that fixed or mobile, it is crucial to understand the context in which the application level measurements operate their capabilities and limitations. To this end in this paper we discuss some of the fundamentals of computer network performance measurements and in particular the key aspects to consider when using application level measurements to estimate network performance properties.

  • 69.
    Arlos, Patrik
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    On the Quality of Computer Network Measurements2005Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Datornät används i mer och mer i vårt dagliga liv, de används för att telefonera, läsa tidningar, se på TV, handla, boka resor etc. På grund av denna diversiteten bland tjänsterna så har mätningar blivit populära under senare år. Detta då de förser nätverksforskningen, utvecklingen och driften med data som används för trafik modellering, prestanda och trend analys. Kvaliteten på dessa mätningar kommer därför direkt påverka resultaten av dessa aktiviteter och därför vår uppfattning av nätverket och dess tjänster. I denna avhandling ger vi en systematisk översikt av datornätverks mätningar och en omfattande översikt av de faktorer som påverkar kvaliteten av prestanda parametrar som tas fram via mätningar. Detta görs genom ett nytt ramverks som beskriver de fyra moduler som påverkar mätningarnas kvalitet: generering, mätning, analys och visualisering. En av de stora källorna till kvalitets problem är noggrannheten på tidstämplar. Dessa tidstämplar beskriver när händelser skedde i nätverket. På grund av detta så presenterar vi en metod som kan uppskatta den tidstämpling noggrannhet som man kan få från mätverktyg, både hård och mjukvara. Metoden används för att utvärdera noggrannheten på några vanliga verktyg, två hårdvarubaserade system (Agilent J6800/J6830A och Endace DAG 3.5E) samt mjukvarubaserade system (Packet Capture Library). Vidare så diskuteras påverkan som analysen har på kvaliteten, och ett exempel ges på hur ett prestanda mått (bitrate) påverkas av mätsystem (hård/mjukvara) och analys metod. Avhandlingen innehåller dessutom utvärderingar av trafik generatorer, applikations mätningar och kvaliteten på mättningar gjorda med PING och J-OWAMP. Huvudslutsatsen i arbetet är att mätsystem och verktyg måste kalibreras, verifieras och valideras innan de används. Baserat på detta så presenterar vi en riktlinje över hur man gör detta.

  • 70.
    Arlos, Patrik
    et al.
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    A Method to Estimate the Timestamp Accuracy of Measurement Hardware and Software Tools2007Konferensbidrag (Refereegranskat)
    Abstract [en]

    Due to the complex diversity of contemporary Internet applications, computer network measurements have gained considerable interest during the recent years. Since they supply network research, development and operations with data important for network traffic modelling, performance and trend analysis etc., the quality of these measurements affect the results of these activities and thus the perception of the network and its services. One major source of error is the timestamp accuracy obtained from measurement hardware and software. On this background, we present a method that can estimate the timestamp accuracy obtained from measurement hardware and software. The method is used to evaluate the timestamp accuracy of some commonly used measurement hardware and software. Results are presented for the Agilent J6800/J6830A measurement system, the Endace DAG 3.5E card, the Packet Capture Library (PCAP) either with PF_RING or Memory Mapping, and a RAW socket using either the kernel PDU timestamp (ioctl) or the CPU counter (TSC) to obtain timestamps.

  • 71. Arlos, Patrik
    et al.
    Fiedler, Markus
    Accuracy Evaluation of Ping and J-OWAMP2006Konferensbidrag (Refereegranskat)
    Abstract [sv]

    Noggrannheten på Ping och J-OWAMPs resultat utvärderas.

  • 72. Arlos, Patrik
    et al.
    Fiedler, Markus
    Influence of the Packet Size on the One-Way Delay in 3G Networks2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    We currently observe a rising interest in mobile broadband, which users expect to perform in a similar way as its fixed counterpart. On the other hand, the capacity allocation process on mobile access links is far less transparent to the user; still, its properties need to be known in order to minimize the impact of the network on application performance. This paper investigates the impact of the packet size on the minimal one-way delay for the uplink in third-generation mobile networks. For interactive and real-time applications such as VoIP, one-way delays are of major importance for user perception; however, they are challenging to measure due to their sensitivity to clock synchronization. Therefore, the paper applies a robust and innovative method to assure the quality of these measurements. Results from measurements from several Swedish mobile operators show that applications can gain significantly in terms of one-way delay from choosing optimal packet sizes. We show that, in certain cases, an increased packet size can improve the one-way delay performance at best by several hundred milliseconds.

  • 73. Arlos, Patrik
    et al.
    Fiedler, Markus
    Influence of the Packet Size on the One-Way Delay on the Down-link in 3G Networks2010Konferensbidrag (Refereegranskat)
    Abstract [sv]

    Vi utvärderar hur OWD i down-link för 3G (WCDMA/HSDPA) nätverk påverkas av paketstorleken. Vi redogör data för tre Svenska operatörer.

  • 74. Arlos, Patrik
    et al.
    Fiedler, Markus
    Nilsson, Arne A.
    A Distributed Passive Measurement Infrastructure2005Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we describe a distributed passive measurement infrastructure. Its goals are to reduce the cost and configuration effort per measurement. The infrastructure is scalable with regards to link speeds and measurement locations. A prototype is currently deployed at our university and a demo is online at http://inga.its.bth.se/projects/dpmi. The infrastructure differentiates between measurements and the analysis of measurements, this way the actual measurement equipment can focus on the practical issues of packet measurements. By using a modular approach the infrastructure can handle many different capturing devices. The infrastructure can also deal with the security and privacy aspects that might arise during measurements.

  • 75. Arlos, Patrik
    et al.
    Kommalapati, Ravichandra
    Fiedler, Markus
    Evaluation of Protocol Treatment in 3G Networks2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this work, we present a systematic study of how the traffic of different transport protocols (UDP, TCP and ICMP) is treated, in three operational Swedish 3G networks. This is done by studying the impact that protocol and packet size have on the one-way-delay (OWD) across the networks. We do this using a special method that allows us to calculate the exact OWD, without having to face the usual clock synchronization problems that are normally associated with OWD calculations. From our results we see that all three protocols are treated similarly by all three operators, when we consider packet sizes that are smaller than 250~bytes and larger than 1100~bytes. We also show that larger packet sizes are given preferential treatment, with both smaller median OWD as well as a smaller standard deviation. It is also clear that, ICMP is given a better performance compared to TCP and UDP.

  • 76.
    Arslan, Muhammad
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    , Usman
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    PERFORMANCE EVALUATION OF VIDEO QUALITY ASSESSMENT METHODS BASED ON FRAME FREEZING2014Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    A Digital Video Communication System consists of a video encoder, a channel through which the video is transmitted and finally a video decoder. These three phases can cause different kinds of impairments or degradations in the quality of a video. One of the degradations that takes place due to an error prone channel is frame freezing and it affects the quality of a video. Frame freezing is a phenomenon in which a particular frame is repeated (displayed) for a certain period of time until the next correct frame is received hence producing a pause or a freeze in a video sequence. Frame freezing can be single or multiple depending on the channel characteristics. Research is being conducted in order to devise a metric which can help in quantifying a video sequence on the basis of its quality. Researchers design metrics and then using their mathematical models, they compare their results with subjective measurements. Subjective measurements help in telling the preciseness and correctness of the metric that whether the quality assessment metric is close enough to subjective test measurements. In this report, three metrics used for video quality assessment have been studied and compared mathematically as well as by careful experiments. The three metrics, chosen for this study, work on No Reference (NR) method for judging the quality of a video. Subjective tests have been performed keeping in view of the recommendations of ITU (International Telecommunication Union). After the study of these three metrics, their advantages and disadvantages over each other have been discussed and the metric that performs the best under certain conditions has been proposed. Finally, a conclusion has been made for the metric that performs the best and also for the metric that performs the worse or even does not perform at all under certain conditions.

  • 77.
    Arslan, Ömer
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap.
    Anjorin, Olufemi Emmanuel
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap.
    Performance Evaluation of Packet Scheduling Algorithms for LTE Downlink2012Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    Long Term Evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) is designed to revolutionize mobile broadband technology with key considerations of higher data rate, improved power efficiency, low latency and better quality of service. It promises high peak data rates of 100 Mbps downlink and 50 Mbps uplink transmissions and can operate in different bandwidths ranging from 1.4 MHz up to 20 MHz. Scheduler makes a decision on allocation of Resource Blocks (RB) to User Equipments (UE) through the frequency and time domains. Channel Quality Indicator (CQI) is used as a main parameter during the decision process. This master thesis focuses on performance of LTE downlink scheduling. Round Robin (RR), Best CQI and a proposed Empirical scheduling solution are investigated under different bandwidth and antenna configurations.

  • 78.
    Aruchamy, Logabharathi
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Analysis of Radio Access Network Buffer Filling Based on Real Network Data2012Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    The 3G and 4G networks have drastically improved availability and quality in data transmission for bandwidth hungry services such as video streaming and location-based services. As 3G networks are very widely deployed, there exists increased capacity requirement and transport channel allocation to simultaneous users under a particular cell. Due to this reason, adequate resources are not available, which in turn degrades both service quality and user experienced quality. This research aims at understanding the characteristics of buffer filling during dedicated channel (DCH) transmission under fixed bit-rate assumptions on a per-user level taking different services into consideration. Furthermore, the resource utilisation in terms of empty buffer durations and user throughput achieved during dedicated channel transmission are also analysed for different data services existing in the mobile networks. The traces are collected from a real network and characteristics of the traffic are analysed prior to understanding its buffer filling in Radio Network Controller (RNC) during downlink data transmission. Furthermore, the buffer is modelled with some series of assumptions on channel bit-rates and simulations are performed taking single user scenario into consideration, for different services with the help of obtained traces as input to the buffer. This research is helpful in understanding the RNC buffer filling for different services, in turn yielding possible understanding on the existing transport channel switching scenario. With the help of analysing the buffer filling for different services and transport channel utilisation, we learn that most of the data services show low DCH utilisation of approximately around 20% and also found to have 80% of the total DCH session duration with empty buffer, causing sub-optimal radio resource utilization.

  • 79. Arvidsson, Åke
    High Level B-ISDN/ATM Traffic Management in Real Time1995Ingår i: Performance Modelling and Evaluation of ATM Networks / [ed] Kouvatsos, Demetres, London: Chapman & Hall , 1995, s. 177-207Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    We study real time traffic management in the perspective of a four-level model of traffic variations: cells, bursts, sessions, and links. Our interest is focused on the two latter levels: Using virtual channels (VCs) and virtual paths (VPs) as the managed entities on the two levels respectively, we put forward a simple and robust strategy for traffic management in real time: All nodes simultaneously monitor offered traffics and forward the result to a network management centre (NMC); The NMC computes a new set of optimal VPs and compares the result to the existing network; If a change appears profitable, the necessary information is sent back to the nodes and the new design is implemented. Applying our strategy to control general networks subject to traffics which in advance are known only as expectations, we develop simple methods for traffic observation, the optimal observation interval, a fast and efficient algorithm to compute VP networks, a test to determine whether to implement a new design in which costs related to lost traffic are compared to processing costs, and the optimal updating interval. Running our strategy in a simulator, we discover a considerable adaptivity, large savings in transmission capacity, and a performance far better than achieved by fixed redesign according to forecasts. Finally we discuss limits to the range of variations within which our strategy can be applied. The present work applies both to networks using SDH/SONET and/or networks based on ATM, i.e. both to present public switched telephony networks and broadband inte- grated services digital networks, and is a summary and extension of earlier works within this area [3{9].

  • 80. Arvidsson, Åke
    Management of Reconfigurable Virtual Path Networks1994Ingår i: The Fundamental Role of Teletraffic in the Evolution of Telecommunication Networks / [ed] Roberts, James; Labetoulle, Jaques, Amsterdam: Elsevier , 1994, s. 931-940Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    We study dynamically rearrangable end-to-end transport networks by means of SDH/SONET and/or ATM virtual paths. The concept and its advantages are brie y reviewed and we propose a new algorithm for designing such networks. Our algorithm provides integer solutions, handles non-linear equivalent bandwidths, finds its own paths, and allows for an arbitrary design optimisation criterion. It is found to perform equal to or better than an earlier, comparable though more restricted, algorithm. We also put forward a strategy for managing virtual paths in real time. It consists of a repeated cycle of on-line measurement of offered traffics followed by the design and implementation of a new virtual path network. Methods and parameters for traffic measurements and network updating frequency are studied and optimised. Applying the strategy to rearrangeable networks subject to variable traffics in a simulator, we discover considerable gains and a robustness in our parameter settings.

  • 81. Arvidsson, Åke
    On Dynamic Capacity Management in Voice/Frame Relaying Networks1992Konferensbidrag (Refereegranskat)
    Abstract [en]

    We consider call admission and capacity management in a dynamically reconfigurable network that carries a multitude of traffics. Our approach is a heuristic capacity as- signment algorithm designed to maximise an arbitrary profit function. The algorithm is based on the concept of equivalent circuits, i.e. a given relationship between transmis- sion capacities and call handling capabilities expressed as effective numbers of circuits. Such relationships are examined for the two traffics of our application, voice and frame relaying. Methods and results are independent of the transfer mode used.

  • 82. Arvidsson, Åke
    On the Usage of Virtual Paths, Virtual Channels, and Buffers in ATM Traffic Management1995Konferensbidrag (Refereegranskat)
    Abstract [en]

    Traffic in ATM networks can be described by numerous parameters. On a per session basis, one may use peak rate, average rate, sustainable rate, average burst duration, average silence duration, and others. In a longer time scale, parameters like the average and peakedness of connection request interarrival times, the average and variance of session holding times, and so on are proposed. Theoretically, users should provide the former parameters and network operators the latter. In reality, however, few users can be expected to provide all sorts of statistical information about their traffic in advance, and operators do not have enough experience to prepare traffic forecasts for new services and applications. Moreover, even if the information could be provided, the lack of simple yet valid traffic models for ATM networks means that it is far from clear how such information should be used. Realising that ATM networks, which are already being built, at least for the next few years will have to operate under these uncertain conditions, we propose a robust and forgiving network design and traffic management strategy. The idea is to use only little information about offered traffics and then dynamically control resource allocations, so as to provide acceptable quality of service combined with high utilisation. The network design is based on the idea of keeping congestion at the edges of the net- work, so that the operating areas of fast congestion control mechanisms are minimised. Traffic variations are characterised by a model of six layers, each of which is assigned a corresponding layer in a traffic management model. We define the functionalities of each level in the latter modell and review possible implementations. In particular, we report on an implementation of two of these layers and discuss in some detail how a third one could be added.

  • 83. Arvidsson, Åke
    Real Time Management of Virtual Paths1994Konferensbidrag (Refereegranskat)
    Abstract [en]

    We propose a simple and robust automatic strat- egy for managing SDH/SONET and/or ATM virtual paths in real time to handle slow traffic variations. It consists of on-line measurements of offered traffics followed by the design and possi- ble implementation of a new virtual path network in a repeated cycle. Methods and parameters for traffic measurements and network updating are studied and optimised to achieve maximal traffic carrying capability at minimal cost. Applying our strat- egy to networks subject to partially unknown, variable traffics we discover a considerable adaptivity, large savings in transmis- sion capacity, and a performance far better than achieved by deterministic management.

  • 84. Arvidsson, Åke
    Real Time Traffic Management by Dynamic Bandwidth Allocation1995Konferensbidrag (Refereegranskat)
    Abstract [en]

    We introduce a six layer model of traffic variations and a corresponding model of management actions. In particular, we traffic study real time traffic management on the traffic and session levels which correspond to variations on the hour and minute levels. Using virtual paths (VPs) and virtual channels (VCs) as the managed entities on the two levels respectively, we put forward a simple and robust strategy for traffic management in real time: For slow variations, i.e. on the traffic level, all nodes simultaneously monitor offered traffics and forward the result to a network management centre (NMC); The NMC computes a new set of optimal VPs compares the result to the existing network; If a change appears profitable, the necessary information is sent back to the nodes and the new design is implemented. For fast variations, i.e. on the session level, dynamic routing schemes similar to those of public switched telephone networks are employed. Applying our strategy to control general networks subject to traffics which in advance are known only as expectations, we develop simple methods for traffic observation, derive the optimal observation interval, brie y review algorithms to compute VP networks, develop a cost optimal test to determine whether to implement a new design or not, and derive the optimal updating interval. Running our strategy in a simulator, we discover a considerable adaptivity and a performance far better than obtained by alternative methods.

  • 85. Arvidsson, Åke
    Strategies for Dynamic Capacity Management1993Konferensbidrag (Refereegranskat)
    Abstract [en]

    We study networks based on virtual paths, i.e. rearrangable end-to-end transport network. Virtual paths networks are readily implemented in any network using the synchronous digital hierarchy and/or the asynchronous transfer mode. The concept and its advantages, for example cost savings, network operation simplification and enhanced network management capabilities, are discussed. Algorithms for virtual path designs are reviewed and a new algorithm is presented which is found to compare favourably with the algorithm providing the most similar features. Applying it to a real network, we turn to operational aspects of reconfigurable networks such as methods and parameters for traffic estimation and network updating. The validity of the results is demonstrated by means of simulations of a number of networks subject to variable traffics.

  • 86. Arvidsson, Åke
    Strategies for Dynamic Network Management1993Konferensbidrag (Refereegranskat)
    Abstract [en]

    We study management of transport networks based on virtual paths, i.e. rearrangable end-to-end transport network \highways". Among its main advantages are found cost savings, network op- eration simplification and enhanced network management capabilities. Virtual paths networks are readily implemented in any network using the synchronous digital hierarchy and/or the asyn- chronous transfer mode. Algorithms for virtual path designs are reviewed and found to have a few shortcomings. A new algorithm is therefore proposed and it is found to compare favourably with the algorithm providing the most similar features. Applying the proposed algorithm to a large number of networks, we discuss operational con- siderations associated with reconfigurable networks and investigate simple traffic estimation pro- cedures and their performance in this context. Finally, the choice of reconfiguration parameters such as updating frequency, and the impact of network design time are examined.

  • 87. Arvidsson, Åke
    Traffic Management in ATM Networks: A Proposal for Imperfect Traffic Information1995Konferensbidrag (Refereegranskat)
    Abstract [en]

    Traffic in ATM networks can be described by numerous parameters. On a per session basis, one may use peak rate, average rate, sustainable rate, average burst duration, average silence duration, and others. In a longer time scale, parameters like the average and peakedness of connection request arrivals, the average and variance of session holding times, and so on are proposed. Theoretically, users should provide the former parameters and network operators the latter. In reality, however, few users can be expected to provide all sorts of statistical information about their traffic in advance, and operators do not have enough experience to prepare traffic forecasts for new services and applications. Moreover, even if the information could be provided, the lack of simple yet valid traffic models for ATM networks means that it is far from clear how it should be used. Realising that ATM networks, which are already being built, at least for the next few years will have to operate under these uncertain conditions, we focus on robust and forgiving strategies for traffic management. The idea is to use only little information about offered traffics and then dynamically control resource allocations, so as to provide acceptable quality of service combined with high utilisation. We give some draft proposals in this direction and point at some open research issues.

  • 88. Arvidsson, Åke
    et al.
    Berry, Les
    Harris, Richard
    Performance Comparison of Bursty Traffic Models1991Konferensbidrag (Refereegranskat)
    Abstract [en]

    Models of bursty arrival processes are reviewed and compared with re- spect to their in uence on the performance of a single server system. Considerable variations are found between different models fitted to the same traffic, though some models exhibit similar behaviour. Comparing the ability of the models to reproduce the performance of an explicitly given parcel they all tend to fail.

  • 89. Arvidsson, Åke
    et al.
    Harris, Richard
    Analysis of the Accuracy of Bursty Traffic Models1993Konferensbidrag (Refereegranskat)
    Abstract [en]

    Traffic models are an essential component of performance analyses of telecommunication networks. This paper investigates the modeling of bursty traffic streams in both single source and multiple source environments. Using a ranking scheme it is shown that, for the single server case, the switched Poisson process models performed the best and that for the multiple source case, models based on the switched Poisson process, or its discrete version (switched Bernoulli) together with the threshold model may give the closest match to the performance of the “real data“. The results also seem to suggest that for traffic for which there is no known, ideal model, a traffic-oriented fitting method performs better than a model oriented one. This study has concentrated on a particular set of “real data” and it has not tried to consider the many different types of bursty traffic, since, at the time of commencing this study, there was little real data available

  • 90. Arvidsson, Åke
    et al.
    Harris, Richard
    Performance Comparison of Models of Individual and Merged Bursty Traffics1991Konferensbidrag (Refereegranskat)
  • 91. Arvidsson, Åke
    et al.
    Harris, Richard
    Performance Comparison of Models of Individual and Merged Bursty Traffics1992Konferensbidrag (Refereegranskat)
  • 92. Arvidsson, Åke
    et al.
    Hederstierna, Anders
    Hellmer, Stefan
    Forecasting Cellular Mobile Traffic: An Econometric Approach2006Konferensbidrag (Refereegranskat)
    Abstract [en]

    We consider the problem of explaining and forecasting the volume of cellular mobile traffic in a long-term perspective. To this end, we create a model of a market with both economic and non-economic variables, viz. the state of the economy, the current price level and the penetration effect on the market in question. We measure these variables by using publicly available data and by applying income theories and by combining theories of demand and technology diffusion. Applying the model to three markets, viz. China, Italy and Sweden, we show that it performs very well in explaining and predicting the volume of cellular mobile traffic. Noting the qualitative differences between these markets, we conclude that the model has some universality in that the results are comparable for all of them

  • 93. Arvidsson, Åke
    et al.
    Holender, Wlodek
    Karlsson, Torgny
    Reduction of Routing Complexity in Telecommunication Networks by a Novel Decomposition Method1996Konferensbidrag (Refereegranskat)
    Abstract [en]

    Routing problems are often encountered when designing and managing telecommuni- cation networks. Today, routing problems are affected by the growing sizes of networks, which increase the complexity, and by introduction of new services and technologies, which rise the demands. Rather than resorting to entirely heuristic algorithms and/or large data bases with off-line precomputed routing information for various situations, we propose a a new decomposition method whereby any routing algorithm is speeded up considerably, thus permitting the deployment of well founded routing algorithms even for real time purposes. In our paper, we present this new method in formal terms, and apply it to a real routing problem. Finally, investigating the performance of our fast implementation by comparing it to the optimal, non-accelerated solution, we find that considerable time savings can be made at a limited cost in terms of non-optimality of the final solution. It is also emphasised that in real-time applications with non-constant traffics, this nominal degradation might be more than compensated for by the prompt delivery.

  • 94. Arvidsson, Åke
    et al.
    Lind, Christer
    On the Validity of Some Markovian Models in ATM Traffic Modelling1995Konferensbidrag (Refereegranskat)
    Abstract [en]

    Markov modulated models are often used to model traffic in a network. How well the processes really capture the essentials of real traffic is less known. We review some of these models and apply a number of associated fitting methods to an Ethernet traffic in different timescales. The fitted models are then used as input to a buffer where buffer occupancies are used as a measure of the goodness of the models. Also, the ability of a fitting method to correctly model the traffic when applied to traffic generated from a model that the fitting method was intended for is examined.

  • 95. Arvidsson, Åke
    et al.
    Lind, Christer
    Using markovian Models to Replicate Real ATM Traffics1996Ingår i: ATM Networks: Performance Modelling an Analysis / [ed] Kouvatsos, Demetres, London: Chapman & Hall , 1996, s. 39-54Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 96. Arvidsson, Åke
    et al.
    Pettersson, Stefan
    Angelin, Lars
    Congestion Control in Intelligent Networks for Real Time Performance and Profit Optimisation1996Konferensbidrag (Refereegranskat)
    Abstract [en]

    Current developments in technologies and markets stress the importance of exible and robust performance optimisation and congestion control. In intelligent networks, congestion control has traditionally taken a purely technical view and focused on pro- tecting individual nodes from harmful overloads. We take a profit oriented, network wide view and develop a congestion control mechanism to ensure real time performance under profit maximisation. Numerical studies in a simulator show that the proposed mechanism is robust and, in particular in overloaded states, provides a substantial improvement in comparison to conventional load control mechanisms.

  • 97. Arvidsson, Åke
    et al.
    Pettersson, Stefan
    Angelin, Lars
    Profit Optimal Congestion Control in Intelligent Networks1997Ingår i: 15th International Teletraffic Congress on Teletraffic Contributions for the Information / [ed] Ramaswami, V.; Wirth, P.E., WASHINGTON, DC: ELSEVIER SCIENCE PUBL B V , 1997, s. 911-920Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Current developments in technologies and markets stress the importance of exible and robust performance optimisation and congestion control. In intelligent networks, conges- tion control has traditionally taken a mainly technical view and focused on protecting individual nodes from harmful overloads. We take a profit oriented, network wide view and develop a congestion control mechanism to ensure profit maximisation under real time performance. Numerical studies in a simulator show that the proposed mechanism is robust and, in particular in overloaded states, provides a substantial improvement in comparison to conventional load control mechanisms.

  • 98.
    Asghar, Gulfam
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Azmi, Qanit Jawed
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Security Issues of SIP2010Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    Voice over IP (VoIP) services based on Session Initiation Protocol (SIP) has gained much attention as compared to other protocols like H.323 or MGCP over the last decade. SIP is the most favorite signaling protocol for the current and future IP telephony services, and it‘s also becoming the real competitor for traditional telephony services. However, the open architecture of SIP results the provided services vulnerable to different types of security threats which are similar in nature to those currently existing on the Internet. For this reason, there is an obvious need to provide some kind of security mechanisms to SIP based VOIP implementations. In this research, we will discuss the security threats to SIP and will highlight the related open issues. Although there are many threats to SIP security but we will focus mainly on the session hijacking and DoS attacks. We will demonstrate these types of attacks by introducing a model/practical test environment. We will also analyze the effect and performance of some the proposed solutions that is the use of Network Address Translation (NAT), IPSec, Virtual Private Networks (VPNs) and Firewalls (IDS/IPS) with the help of a test scenario.

  • 99.
    Ataeian, Seyed Mohsen
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Darbandi, Mehrnaz Jaberi
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Analysis of Quality of Experience by applying Fuzzy logic: A study on response time2011Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    To be successful in today's competitive market, service providers should look at user's satisfaction as a critical key. In order to gain a better understanding of customers' expectations, a proper evaluations which considers intrinsic characteristics of perceived quality of service is needed. Due to the subjective nature of quality, the vagueness of human judgment and the uncertainty about the degree of users' linguistic satisfaction, fuzziness is associated with quality of experience. Considering the capability of Fuzzy logic in dealing with imprecision and qualitative knowledge, it would be wise to apply it as a powerful mathematical tool for analyzing the quality of experience (QoE). This thesis proposes a fuzzy procedure to evaluate the quality of experience. In our proposed methodology, we provide a fuzzy relationship between QoE and Quality of Service (QoS) parameters. To identify this fuzzy relationship a new term called Fuzzi ed Opinion Score (FOS) representing a fuzzy quality scale is introduced. A fuzzy data mining method is applied to construct the required number of fuzzy sets. Then, the appropriate membership functions describing fuzzy sets are modeled and compared with each other. The proposed methodology will assist service providers for better decision-making and resource management.

  • 100.
    Atchukatla, Mahammad suhail
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Algorithms for efficient VM placement in data centers: Cloud Based Design and Performance Analysis2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Content: Recent trends show that cloud computing adoption is continuously increasing in every organization. So, demand for the cloud datacenters tremendously increases over a period, resulting in significantly increased resource utilization of the datacenters. In this thesis work, research was carried out on optimizing the energy consumption by using packing of the virtual machines in the datacenter. The CloudSim simulator was used for evaluating bin-packing algorithms and for practical implementation OpenStack cloud computing environment was chosen as the platform for this research.

     

    Objectives:  In this research, our objectives are as follows

    • Perform simulation of algorithms in CloudSim simulator.
    • Estimate and compare the energy consumption of different packing algorithms.
    • Design an OpenStack testbed to implement the Bin packing algorithm.

     

    Methods:

    We use CloudSim simulator to estimate the energy consumption of the First fit, the First fit decreasing, Best fit and Enhanced best-fit algorithms. Design a heuristic model for implementation in the OpenStack environment for optimizing the energy consumption for the physical machines. Server consolidation and live migration are used for the algorithms design in the OpenStack implementation. Our research also extended to the Nova scheduler functionality in an OpenStack environment.

     

    Results:

    Most of the case the enhanced best-fit algorithm gives the better results. The results are obtained from the default OpenStack VM placement algorithm as well as from the heuristic algorithm developed in this simulation work. The comparison of results indicates that the total energy consumption of the data center is reduced without affecting potential service level agreements.

     

    Conclusions:

    The research tells that energy consumption of the physical machines can be optimized without compromising the offered service quality. A Python wrapper was developed to implement this model in the OpenStack environment and minimize the energy consumption of the Physical machine by shutdown the unused physical machines. The results indicate that CPU Utilization does not vary much when live migration of the virtual machine is performed.

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