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  • 51.
    Alexiou, Nikolaos
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsnät.
    Laganá, Marcello
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsnät.
    Gisdakis, Stylianos
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsnät.
    Khodaei, Mohammad
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsnät.
    Papadimitratos, Panagiotis
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsnät.
    VeSPA: Vehicular security and privacy-preserving architecture2013Inngår i: HotWiSec 2013: Proceedings of the 2013 ACM Workshop on Hot Topics on Wireless Network Security and Privacy, 2013, 19-23 s.Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Vehicular Communications (VC) are reaching a near deploment phase and will play an important role in improving road safety, driving efficiency and comfort. The industry and the academia have reached a consensus for the need of a Public Key Infrastructure (PKI), in order to achieve security, identity management, vehicle authentication, as well as preserve vehicle privacy. Moreover, a gamut of proprietary and safety applications, such as location-based services and pay-as-you-drive systems, are going to be offered to the vehicles. The emerging applications are posing new challenges for the existing Vehicular Public Key Infrastructure (VPKI) architectures to support Authentication, Authorization and Accountability (AAA), without exposing vehicle privacy. In this work we present an implementation of a VPKI that is compatible with the VC standards. We propose the use of tickets as cryptographic tokens to provide AAA and also preserve vehicle privacy against adversaries and the VPKI. Finally, we present the efficiency results of our implementation to prove its applicability.

  • 52.
    Alfredsson, Stefan
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Del Giudice, Giacomo
    Politecnico di Bari, Italy.
    Garcia, Johan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    De Cicco, Luca
    Ecole superieure d'Electricite, France; Politecnico di Bari, Italy.
    Mascolo, Saverio
    Politecnico di Bari, Italy.
    Impact of TCP Congestion Control on Bufferbloat in Cellular Networks2013Inngår i: Proceedings of the 14th IEEE International Symposium on a World of Wireless, Mobile and Multimedia Networks (WoWMoM 2013) / [ed] Angelos Lazaris, Balaji Rengarajan, IEEE Press, 2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The existence of excessively large and too filled network buffers, known as bufferbloat, has recently gained attention as a major performance problem for delay-sensitive applications. One important network scenario where bufferbloat may occur is cellular networks.

    This paper investigates the interaction between TCP congestion control and buffering in cellular networks. Extensive measurements have been performed in commercial 3G, 3.5G and 4G cellular networks, with a mix of long and short TCP flows using the CUBIC, NewReno and Westwood+ congestion control algorithms. The results show that the completion times of short flows increase significantly when concurrent long flow traffic is introduced. This is caused by increased buffer occupancy from the long flows. In addition, for 3G and 3.5G the completion times are shown to depend significantly on the congestion control algorithms used for the background flows, with CUBIC leading to significantly larger completion times.

  • 53.
    Alfredsson, Stefan
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Del Giudice, Giacomo
    Politecnico di Bari, Italy.
    Garcia, Johan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    De Cicco, Luca
    Ecole superieure d'Electricite, France; Politecnico di Bari, Italy.
    Mascolo, Saverio
    Politecnico di Bari, Italy.
    Observations of Bufferbloat in Swedish Cellular Networks2013Inngår i: Proceedings of the 9th Swedish National Computer Networking Workshop (SNCNW 2013) / [ed] Bengt Ahlgren, 2013Konferansepaper (Fagfellevurdert)
  • 54. Alhammouri, M.
    et al.
    Muftic, Sead
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Data- och systemvetenskap, DSV.
    A design of an access control model for multilevel-security documents2008Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper we describe an access control model for multilevel-security documents, those structured into multiple sections based on certain security classifications. Our access control system uses XACML policies to allow documents, whose contents have varying sensitivity levels, to be created, viewed, and edited by groups that have members with varying clearance levels, while enforcing the required security constraints.

  • 55.
    Ali, Rahman
    Linköpings universitet, Institutionen för systemteknik, Elektroniksystem. Linköpings universitet, Tekniska högskolan.
    Design of Building Blocks in Digital Baseband Transceivers for Body-Coupled Communication2014Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Advances in communication technologies continue to increase information sharing among the people.~Short-range wireless networking technologies such as Bluetooth or ZigBee, which are mainly used for data transfer over short range, will, however, suffer from network congestion, high power consumption and security issues in the future.

    The body-coupled communication (BCC), a futuristic short-range wireless technology, uses the human body as a transmission medium. In BBC channel, a small electric field is induced onto the human body which enables the propagation of a signal between communication devices that are in the proximity or direct contact with the human body. The direct baseband transmission and simple architecture make BCC an attractive candidate for a future short-range wireless communication technology in particular applications such as body area network.

    The main focus of this thesis is on the design and implementation of digital baseband transmitter and receiver for the body-coupled communication. The physical layer (PHY) implementation of the digital baseband transmitter and receiver is inspired from the IEEE 802.3 Ethernet transmission protocol. The digital design is implemented at RTL level using hardware description language (VHDL). The functionality of the digital baseband transmitter and receiver is demonstrated by developing data transfer application layers.

  • 56.
    Ali Tandra, Sabrina
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Rizvi, S.M. Sarwarul Islam
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Security for Cloud Based Services2014Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Cloud computing is a new buzzword in the modern information technology world. Today cloud computing can be considered as a service, similar to the way that electricity is considered a service in urban areas. A cloud user can utilize different computing resources (e.g. network, storage, software application), whenever required, without being concerned with the complex underlying technology and infrastructure architecture. The most important feature is that the computing resources are available whenever they are needed. Additionally, users pay only for the resource they actually use. As a result, cloud users can easily scale their information technology infrastructure, based on their business policy and requirements. This scalability makes the business process more agile.

    The motivation for this thesis was the need for a suitable set of security guidelines for ifoodbag (and similar companies) when implementing web applications in the cloud. The goal of this thesis is to provide security in a system, being developed in another Master’s thesis project, to implement the ifoodbag web application in a cloud. To achieve this goal, we began by identifying the risks, threats, and vulnerabilities in the system model proposed by these other students for their implementation. A study was made of several different security mechanisms that might reduce or eliminate risks and secure the most vulnerable points in the proposed system’s design. Tests of these alternatives were conducted to select a set of mechanisms that could be applied to the proposed system’s design. Justification for why these specific mechanisms were selected is given. The tests allowed the evaluation of how each of these different security mechanisms affected the performance of the system. This thesis presents the test results and their analysis. From this analysis a set of mechanisms were identified that should be included in the prototype of the system. In conclusion, we found that DNSSEC, HTTPS, VPN, AES, Memcached with SASL authentication, and elliptic curve cryptography gave the most security, while minimizing the negative impact on the system. Additionally, client & server mutual authentication and a multi-level distributed database security policy were essential to provide the expected security and privacy that users would expect under the Swedish Data Protection law and other laws and regulations.

  • 57.
    Ali, Waqas Liaqat
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Securing Safebook: Secure Data Access Control and Key Management for Safebook2013Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Online social networks have become a fast and efficient way of sharing information and experiences. Over the past few years the trend of using social networks has drastically increased with an enormous amount of users’ private contents injected into the providers’ data centers. This has raised concerns about how the users’ contents are protected and how the privacy of users is preserved by the service providers. Moreover, current social networks have been subject to much criticism over their privacy settings and access control mechanism. The providers own the users’ contents and these contents are subject to potential misuse. Many socially engineered attacks have exposed user contents due to the lack of sufficient privacy and access control. These security and privacy threats are addressed by Project Safebook, a distributed peer-to-peer online social networking solution leveraging real life trust. By design Safebook decentralizes data storage and thus the control over user content is no longer in the service provider’s hands. Moreover, Safebook uses an anonymous routing technique to ensure communication privacy between different users.

    This thesis project addresses privacy aware data management for Safebook users and a data access control solution to preserve users’ data privacy and visibility utilizing a peer to peer paradigm. The solution focuses on three sub-problems: (1) preserving the user’s ownership of user data, (2) providing an access control scheme which supports fine grained access rights, and (3) secure key management. In our proposed system, the user profile is defined over a collection of small data artifacts. An artifact is the smallest logical entity of a profile. An artifact could be a user’s status tweak, text comment, photo album metadata, or multimedia contents. These artifacts are then logically arranged to form a hierarchical tree, call the User Profile Hierarchy. The root of the profile hierarchy is the only entry point exposed by Safebook from where the complete user profile can be traversed. The visibility of portions of the user profile can be defined by exposing a subset of profile hierarchy. This requires limiting access to child artifacts, by encrypting the connectivity information with specific access keys. Each artifact is associated with a dynamic access chain, which is an encrypted string and contains the information regarding the child nodes. A dynamic access chain is generated using a stream cipher, where each child’s unique identifier is encrypted with its specific access key and concatenated to form the dynamic access chain. The decryption process will reveal only those child artifacts whose access keys are shared. The access keys are managed in a hierarchical manner over the profile hierarchy. Child artifacts inherit the parent’s access key or their access key can be overridden with a new key. In this way, fine grained access rights can be achieved over a user’s artifacts. Remote users can detect changes in a specific branch of a profile hierarchy and fetch new artifacts through our proposed profile hierarchy update service. On top of the proposed access control scheme, any social networking abstraction (such as groups, circles, badges, etc.) can be easily implemented.

  • 58. Alinia, Bahram
    et al.
    Yousefi, Hamed
    Talebi Mazraeh Shahi, Mohammad Sadegh
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Khonsari, Ahmad
    Maximizing Quality of Aggregation in Delay-Constrained Wireless Sensor Networks2013Inngår i: IEEE Communications Letters, ISSN 1089-7798, Vol. 17, nr 11, 2084-2087 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this letter, both the number of participating nodes and spatial dispersion are incorporated to establish a bi-objective optimization problem for maximizing the quality of aggregation under interference and delay constraints in tree-based wireless sensor networks (WSNs). The formulated problem is proved to be NP-hard with respect to Weighted-sum scalarization and a distributed heuristic aggregation scheduling algorithm, named SDMAX, is proposed. Simulation results show that SDMAX not only gives a close approximation of the Pareto-optimal solution, but also outperforms the best, to our knowledge, existing alternative proposed so far in the literature.

  • 59.
    Alisauskas, Saulius
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Community based testing2013Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Currently, Android is the most popular operating system for mobile devices, but at the same time, the market for Android devices is heavily fragmented in terms of available versions, types of devices, models, form-factors and manufactures. As a result, it is virtually impossible to test applications on all existing devices. Testing on a set of the most popular devices is more realistic but can be expensive, which makes it much more difficult for individual developers to create high quality applications.

    Fortunately, each Android application developer around the world typically owns at least one device which is not used all the time and could be shared with other developers. This way, a community shared pool of Android devices can be created for automated test execution.

    This master thesis reviews existing testing frameworks that are used for testing Android applications and analyzes existing services that in one way or another try to solve the problem of providing affordable ways of performing testing on real devices.  Main result of this thesis project is a working distributed community based testing service that enables developers to easily connect, share, and execute automated test cases on devices that use Android operating system. Moreover, it provides ways of decreasing overall test execution time by executing parts of tests in parallel on multiple devices and aggregating received results.

  • 60.
    Almas, Muhammad Shoaib
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Vanfretti, Luigi
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    PERFORMANCE EVALUATION OF PROTECTION FUNCTIONS FOr IEC 61850-9-2 PROCESS BUS USING REAL-TIME HARDWARE-IN-THE-loop simulation approach2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    With the evolution of Process Bus (IEC 61850-9-2), there is a need to assess the performance of protection schemes using process bus against those where traditional copper wires are implemented. Differential protection is the fundamental and most commonly used protection for transformers, motors and generators. In this paper a power system is modelled in SimPowerSystems and is executed in real-time using Opal-RT’s eMEGAsim real-time simulator. Hardware-in-the loop validation of a process bus implementation for differential protection for a two winding transformer is done by using the differential protection feature in ABB’s RED-670 relay. The event reports generated by the ABB relay during Hardware-in-the-Loop testing are compared for three different scenarios i.e. complete process bus, hybrid process bus and complete traditional topology.   

  • 61.
    Almkvist, Magnus
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Wahren, Marcus
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Preserving Integrity inTelecommunication Networks Opened bythe Parlay Service Interface2002Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This Master’s Thesis in Electrical Engineering concerns the introduction of a Parlay gateway in Skanova’s public circuit switched telephone network, what network integrity problems this brings, and how to preserve the integrity of the network.

    There is a rising demand from the market on Skanova to be able to offer integrated and useful services via their network. Examples of such services are Web Controlled Call Forwarding and Virtual Call Centres. Until now, these services have been implemented with the Intelligent Network concept which is a technology for concentrating the service logic in the telephone network to centralised service platforms within the network operator’s domain. Developing new services in this environment is expensive and therefore, Skanova wants to open the network for third party service providers. The opening of the network is enabled by the introduction of a gateway implementing the open service interface Parlay.

    The crucial point when opening the network for third party service providers is to maintain the integrity of the network. Parlay is an object oriented Application Programming Interface that enables a third party service access to core network resources in a controlled manner.

    The authors’ definition of network integrity is: “the ability of a network to steadily remain in a safe state, while performing according to the expectations and specifications of its owner, i.e. delivering the expected functionality and providing means to charge for utilised network resources”.

    The thesis describes a few services implemented via the Parlay interface and points out examples of activities in these services that may jeopardise the integrity of the network. The described activities belong to one of the two categories: Call Control Functionality or Lack of Charging Instruments.

    The thesis also describes two important methods for addressing encountered integrity problems. The methods are: Parlay Service Level Agreement and Policy Management.</p> Finally, the solutions are compared and the conclusion is that Policy Management is a conformable and flexible method for addressing lots of integrity problems and that these are important qualities, since new integrity problems will arise all the time.

  • 62.
    Almquist, Mathias
    et al.
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska fakulteten.
    Almquist, Viktor
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska fakulteten.
    Vergara Alonso, Ekhiotz Jon
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Nadjm-Tehrani, Simin
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Communication Energy Overhead of Mobiles Games2015Inngår i: MobiGames '15: Proceedings of the 2nd Workshop on Mobile Gaming, Association for Computing Machinery (ACM), 2015, 1-6 s.Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Although a significant proportion of the mobile apps are games there has been little attention paid to their specific characteristics with respect to communication energy. In this paper we select 20 mobile games among the top 100 free Android games, and study their data patterns and communication energy use over a total of 25 hours of playing. The analysis of the energy for communication over 3G networks indicates that there is a wide variation among the games, the largest footprint being 8 times higher than the lowest one. The results also indicates both app-specific and category-specific relations between data pattern and energy use, as well as variations in CPU utilisation.

  • 63. Alonso, Juan M.
    et al.
    Nordhamn, Amanda
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorarkitektur och datorkommunikation.
    Olofsson, Simon
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorarkitektur och datorkommunikation.
    Voigt, Thiemo
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorarkitektur och datorkommunikation.
    Bounds on the lifetime of wireless sensor networks with lossy links and directional antennas2016Inngår i: Wireless Network Performance Enhancement via Directional Antennas: Models, Protocols, and Systems, Boca Raton, FL: CRC Press, 2016, 329-361 s.Kapittel i bok, del av antologi (Fagfellevurdert)
  • 64.
    Al-Sheikhly, Yavor
    KTH, Tidigare Institutioner, Teleinformatik.
    Implementing policy-based network management1999Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The aim of this thesis project is to help Ericsson implement policy-based network management. The department where the work is conducted is migrating to a new management platform, making it suitable to change the approach towards network management at the same time. An overview of the idea of policy based management will be given, together with suggestions on what is needed to successfully implement this strategy. Examples are presented on how to implement certain policies, given the new management platform. Finally, I present my conclusions of what is the proper path to a policy-based network management system for Ericsson’s internal use and describe future extensions.

  • 65.
    Altinkaya, Martin
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Ahmedi, Saman
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    SIP in an Interconnector and Service Provider Role2001Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This Master’s Thesis concerns the technical problems and solutions in the Telia Mobile’s Golden Gate Architecture. The Golden Gate project will bridge service control from the IPnetwork to the circuit switched network. Connecting the different users of PSTN, GSM, W-LAN, and GPRS networks together will require solutions to many problems. Most of the problems have already been defined by Telia. Our task is to evaluate two parts of the Golden Gate architecture, namely the Interconnect- and Service Provider roles.

    The Interconnector provider connects networks of different technical standards and enables other network operators to reach Service Providers on the Internet or other IP-based networks. The role concerns mainly mapping between SS7 signaling and the Session Initiation Protocol (SIP), charging and billing. Via the Interconnector the Service Provider can connect different services to any network.

    We will describe the SIP-protocol in detail and then we will look into the mapping between SS7 and SIP. We will also propose a charging model. It is important to have a solution that supports roaming between the different networks, we will evaluate such a solution. Most of the protocols (INAP, ENUM, MAP and ISUP) that are involved in the Golden Gate architecture are not completely defined. There are many Internet Drafts that discuss the possible functionality of the protocols and the interworking between them. Many different Internet-workgroups are working with these issues. No one seems to have the right answers for the interconnection between the protocols involved.

    Since the IP-telephony will probably replace today’s telephony systems, it is important to ensure a suitable Quality of Service (QoS), security that guarantees privacy, and a fair billing function. These are the three major problems in the IP-telephony world. IP-Telephony or Voice over IP (VoIP) has been on the market for a long time, there are many 'free IP-call sites' that use VoIP, but the quality of the calls are not yet good enough to replace traditional telephony. Our task here is to make sure that the necessary quality of service is provided, and a reliable charging model is used.

  • 66.
    Al-Zubaidy, Hussein Mohammed
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori.
    Dán, György
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsnät.
    Fodor, Viktoria
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsnät.
    Performance of in-network processing for visual analysis in wireless sensor networks2015Inngår i: Proceedings of 2015 14th IFIP Networking Conference, IFIP Networking 2015, IEEE conference proceedings, 2015Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Nodes in a sensor network are traditionally used for sensing and data forwarding. However, with the increase of their computational capability, they can be used for in-network data processing, leading to a potential increase of the quality of the networked applications as well as the network lifetime. Visual analysis in sensor networks is a prominent example where the processing power of the network nodes needs to be leveraged to meet the frame rate and the processing delay requirements of common visual analysis applications. The modeling of the end-to-end performance for such networks is, however, challenging, because in-network processing violates the flow conservation law, which is the basis for most queuing analysis. In this work we propose to solve this methodological challenge through appropriately scaling the arrival and the service processes, and we develop probabilistic performance bounds using stochastic network calculus. We use the developed model to determine the main performance bottlenecks of networked visual processing. Our numerical results show that an end-to-end delay of 2-3 frame length is obtained with violation probability in the order of 10-6. Simulation shows that the obtained bounds overestimates the end-to-end delay by no more than 10%.

  • 67. Ambat, S. K.
    et al.
    Chatterjee, Saikat
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori.
    Hari, K. V. S.
    Adaptive selection of search space in look ahead orthogonal matching pursuit2012Inngår i: 2012 National Conference on Communications, NCC 2012, 2012, 6176852- s.Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Compressive Sensing theory combines the signal sampling and compression for sparse signals resulting in reduction in sampling rate and computational complexity of the measurement system. In recent years, many recovery algorithms were proposed to reconstruct the signal efficiently. Look Ahead OMP (LAOMP) is a recently proposed method which uses a look ahead strategy and performs significantly better than other greedy methods. In this paper, we propose a modification to the LAOMP algorithm to choose the look ahead parameter L adaptively, thus reducing the complexity of the algorithm, without compromising on the performance. The performance of the algorithm is evaluated through Monte Carlo simulations.

  • 68.
    Amin, Yasar
    et al.
    University of Engineering and Technology, Taxila, Punjab, Pakistan.
    Shao, Botao
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektroniksystem. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Chen, Qiang
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektroniksystem. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Zheng, Li-Rong
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektroniksystem. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Tenhunen, Hannu
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektroniksystem. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Electromagnetic Analysis of Radio Frequency Identification Antennas for Green Electronics2013Inngår i: Electromagnetics, ISSN 0272-6343, E-ISSN 1532-527X, Vol. 33, nr 4, 319-331 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This article demonstrates in-depth electromagnetic analysis of a radio frequency identification tag antenna manufactured by inkjet printing technology on different paper substrates to achieve ultra-low cost flexible radio frequency identification tags using a novel hole-matching technique for reducing the consumption of substrate material, and conductive ink. Nevertheless, the electromagnetic properties of the paper substrate are vulnerable to various environmental effects. Thus, the proposed antenna design is optimized for consistent wideband performance throughout the complete UHF radio frequency identification band (860960 MHz) while presenting a greater degree of material insensitivity. An advanced antenna design methodological analysis is performed to accomplish an extended read range, while exhibiting benchmarking results when across cardboard cartons filled with metal or water containing objects.

  • 69.
    Ammar, Doreid
    et al.
    Norwegian Univ Sci & Technol, NOR.
    De Moor, Katrien
    Norwegian Univ Sci & Technol, NOR.
    Xie, Min
    Next Generat Serv, Telenor Res, NOR.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Heegaard, Poul
    Norwegian Univ Sci & Technol, NOR.
    Video QoE Killer and Performance Statistics in WebRTC-based Video Communication2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, we investigate session-related performance statistics of a Web-based Real-Time Communication (WebRTC) application called appear. in. We explore the characteristics of these statistics and explore how they may relate to users' Quality of Experience (QoE). More concretely, we have run a series of tests involving two parties and according to different test scenarios, and collected real-time session statistics by means of Google Chrome's WebRTC-internals tool. Despite the fact that the Chrome statistics have a number of limitations, our observations indicate that they are useful for QoE research when these limitations are known and carefully handled when performing post-processing analysis. The results from our initial tests show that a combination of performance indicators measured at the sender's and receiver's end may help to identify severe video freezes (being an important QoE killer) in the context of WebRTC-based video communication. In this paper the performance indicators used are significant drops in data rate, non-zero packet loss ratios, non-zero PLI values, and non-zero bucket delay.

  • 70.
    Amso, Julian
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Faienza, Achille
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    IPsec Intrusion Detection Analysis: Using data from an Ericsson Ethernet Interface Board2008Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    IP security (IPsec) is commonly used for protection in Virtual Private Networks (VPN). It is also used for the protection of traffic between nodes in third generation (3G) mobile networks. The main duty of telecommunication operators is to assure the quality of service and availability of the network for their users. Therefore knowledge of threats that could affect these requirements is of relevance. Denial of Service (DoS) and other attacks could constitute serious threats in 3G networks and, if successful, they could lead to financial and reputation damage for the telecommunication operator. One of the goals of each telecommunications vendor is to produce equipment and software in such a way as to reduce the risk of successful attacks upon networks built using their equipment and software. This master’s thesis aims to identify the classes of attacks that could affect the regular operation of an IPsec-protected network. Therefore, the IPsec protocol and its possible weaknesses are explained. As practical demonstration of these ideas, an Intrusion Detection Analyzer prototype for an Ericsson Ethernet Interface board was developed to detect anomalous IPsec-protected traffic.

  • 71. Anand, K.
    et al.
    Ganapathy, S.
    Kulothungan, K.
    Yogesh, P.
    Kannan, Anand
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    A Rule Based Approach for Attribute Selection and Intrusion Detection in Wireless Sensor Networks2012Inngår i: International Conference On Modelling Optimization And Computing, Elsevier, 2012, 1658-1664 s.Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, we propose a new rule based attribute selection algorithm for removing the redundant attributes which are used in decision making on intrusions in wireless sensor networks. This work focuses mainly on finding important attributes to find Denial of Service attacks. In addition, we used an enhanced MSVM classification algorithm that was developed by extending the existing MSVM algorithm. The experimental results show that the proposed methods provide high detection rates and reduce false alarm rate. This system has been tested using KDD'99 Cup data set.

  • 72.
    Anchora, Luca
    et al.
    IMT of Lucca.
    Badia, Leonardo
    Università degli Studi di Padova.
    Karipidis, Eleftherios
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Zorzi, Mikele
    Università degli Studi di Padova.
    Capacity Gains due to Orthogonal Spectrum Sharing in Multi-Operator LTE Cellular Networks2012Inngår i: Proceedings of the Ninth International Symposium on Wireless Communication Systems (ISWCS), 2012, 286-290 s.Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Static spectrum allocation leads to resource wastage and inter-operator spectrum sharing is a possible way to improve spectrum efficiency. In this work, we assume that two cellular network operators agree upon sharing part of their spectrum, which can then be dynamically accessed by either of them in a mutually exclusive way. Our goal is to numerically assess the gain, in terms of cell capacity, due to such orthogonal spectrum sharing. Hence, we propose a centralized algorithm that performs coordinated scheduling, in order to numerically evaluate an upper bound on the achievable sum capacity. The algorithm is centralized and exploits complete information on both networks to perform the optimum allocation. The simulation results illustrate the impact of the multiuser diversity and the asymmetry in the traffic load among the networks on the overall achievable gain.

  • 73.
    Anchora, Luca
    et al.
    IMT of Lucca.
    Badia, Leonardo
    Università degli Studi di Padova.
    Zhang, Haibin
    TNO ICT.
    Fahldieck, Torsten
    Bell Labs, Alcatel-Lucent.
    Zhang, Jianshu
    Ilmenau University of Technology.
    Szydelko, Michal
    Wroclaw Research Centre EIT+ .
    Schubert, Martin
    Fraunhofer Institute for Telecommunications HHI.
    Karipidis, Eleftherios
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Haardt, Martin
    Ilmenau University of Technology.
    Resource Allocation and Management in Multi-Operator Cellular Networks with Shared Physical Resources2012Inngår i: Proceedings of the Ninth International Symposium on Wireless Communication Systems (ISWCS), IEEE , 2012, 296-300 s.Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, we focus on next-generation cellular networks and discuss physical resources sharing among the operators. This implies cooperative usage of the available radio frequencies and also infrastructure sharing. In particular, we analyze the spectrum sharing gain achievable at different time scales and the main factors impacting on it. Then, we move towards a wider idea of resource sharing and consider a joint spectrum and infrastructure sharing (full sharing). We describe a two-layer resource management architecture that enables operators to reduce costs while still guaranteeing a good service level. The main findings of our investigations are to quantify the effectiveness of resource sharing and open up new perspectives for the operators of next-generation networks.

  • 74. Andersen, O.
    et al.
    Wisell, David
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. University of Gävle, Sweden.
    Keskitalo, N.
    Stenvard, P.
    Cost effective high performance modular instrumentation, signal generation and signal analysis for future mobile communication systems2007Inngår i: 2007 IEEE Autotestcon, IEEE , 2007, 660-668 s.Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A decrease in life cycle cost is a key issue for testing of mobile communication systems. The rapid development and edge technology requires high performance instruments and state of the art measurement technology. It is desired to use virtual/synthetic instruments and put the measurement technology in software independent of hardware, i.e. software driven measurements. Increased flexibility and modularization, both in hardware and software, are requirements to support the cost decrease. The hardware basis is signal generation and signal analysis. In this paper state of the art signal generation and signal analysis capabilities are demonstrated in a modular and flexible architecture. A direct IF synthesis is used to generate 1 WideBand Code-Division Multiple Access (WCDMA) carrier with more than 72 dB Adjacent Carrier Leakage Ratio (ACLR) 2 carrier with more than 68 dBc ACLR over a total bandwidth of 100 MHz. The signal analysis capabilities, ACLR performance, for a WCDMA carrier is better than -70 dBc and for a continuous wave better than -85 dBc over a bandwidth of 42.5 MHz. The critical down converter in the set up doesn't degrade the performance.

  • 75.
    Andersson, Dan
    KTH, Skolan för teknik och hälsa (STH), Data- och elektroteknik.
    Implementation av prototyp för inomhuspositionering2013Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Utveckling av teknik skapar ständigt nya möjligheter men innebär också stora förändringar för företag och organisationer. Mobiltelefoner, surfplattor, bärbara datorer, mobilkommunikation och molnteknik gör det möjligt idag att inte längre vara bunden av tid, plats eller en enhet för att kunna arbeta. Förändringen innebär att en ny typ av flexibla och yteffektiva kontor med inga fasta arbetsplatser blir allt vanligare. Problemet med de så kallade flexkontoren är att veta var eller när en kollega befinner sig på kontoret är inte lika självklart, framförallt om det är stort kontor med flera våningsplan.

    Målsättningen med detta arbete är att ta fram och implementera en inomhuspositioneringstjänst eller en så kallad Location-Based Service, till företaget Connecta AB. Tjänsten ska göra det möjligt för användare att med hjälp av sin mobiltelefon dela med sig av sin nuvarande arbetsplats i en kontorsmiljö.

    Resultatet av arbetet är en Location Based Service som gör det möjligt för en användare att med hjälp av en Androidtelefon med stöd för kortdistanskommunikationstekniken Near Field Communcication att dela med sig av sin nuvarande arbetsplats. Den molnbaserade serverlösningen Windows Azure används för att lagra registrerade arbetsplatser.

  • 76. Andersson, Emma
    et al.
    Bröhne, Johan
    High Quality of Service in SDN: Bandwidth gurantee with QoS2017Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Video streaming through IP networks has risen rapidly over the recent years, and will continue to do so over the coming years. In addition to this, new technologies such as Virtual Reality and robotics will lead to many new applications that will put high pressure on the networks. To combat these challenges, networks need to be application sensitive, and be able to provide Quality of Service (QoS) based on requirement. Network paradigms like Software Defined Networking (SDN) enables the network to be directly programmable, and could thus solve the challenge. In this thesis, the objective is to research if SDN can provide High QoS.

    Methods are developed to achieve High QoS with SDN. A combination of Differentiated Services Code Point (DSCP) values and DSCP remarking with Meters are used enable High QoS and together they can give bandwidth guarantee. As a result of the thesis, a solid theoretical method is provided for achieving QoS, tests are performed and show that QoS can be implemented in SDN, but it is unable to implement High QoS due to the lack of implementation for Meters with DSCP remarking.

  • 77.
    Andersson, Johan
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    Kleihs, Marcus
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    Routing Interior2013Student paper second term, 5 poäng / 7,5 hpOppgave
    Abstract [sv]

    När datatrafik färdas genom ett nätverk så passerar det routrar och switcharsamtidigt som dessa enheter visar åt vilket håll paketet ska skickas. Detta kallas förrouting. För att paketen ska hitta rätt väg så använder man sig av routingprotokoll,som vägleder trafiken dit de ska, och olika protokoll har olika fördelar samtidigtsom de används vid olika tillfällen. Målet var att skapa ett stort enhetligt nätverksom tål höga belastningar, har en hög uppkopplingsprocent samtidigt som det skavara lätt att expandera i framtiden. Det största problemet var hur trafiken färdasmellan varje kontor, men problem som hur användarna ska vara uppkopplade tillInternet tas upp i rapporten. Nätverket använder sig av OSPF som routingprotokoll.Varje kontor delas in i områden, totallystubby area, vilket kortar nedroutingtabellen i Stockholm. Resultatet blir att snabba beslut tas när paket skaskickas inom ett kontor och när det ska utanför ett kontor så används en defaultroute. Samtidigt som kontoren är lätta att bygga ut då totallystubby area har endefault route till Stockholm.

  • 78.
    Andersson, Martin
    Linköpings universitet, Institutionen för systemteknik, Informationskodning.
    Parametric Prediction Model for Perceived Voice Quality in Secure VoIP2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    More and more sensitive information is communicated digitally and with thatcomes the demand for security and privacy on the services being used. An accurateQoS metric for these services are of interest both for the customer and theservice provider. This thesis has investigated the impact of different parameterson the perceived voice quality for encrypted VoIP using a PESQ score as referencevalue. Based on this investigation a parametric prediction model has been developedwhich outputs a R-value, comparable to that of the widely used E-modelfrom ITU. This thesis can further be seen as a template for how to construct modelsof other equipments or codecs than those evaluated here since they effect theresult but are hard to parametrise.

    The results of the investigation are consistent with previous studies regarding theimpact of packet loss, the impact of jitter is shown to be significant over 40 ms.The results from three different packetizers are presented which illustrates theneed to take such aspects into consideration when constructing a model to predictvoice quality. The model derived from the investigation performs well withno mean error and a standard deviation of the error of a mere 1:45 R-value unitswhen validated in conditions to be expected in GSM networks. When validatedagainst an emulated 3G network the standard deviation is even lower.v

  • 79.
    Andersson, Martin
    Högskolan i Skövde, Institutionen för kommunikation och information.
    SANDBUNKERSEGMENTERING FÖR SMARTPHONES: Automatisk positionsuppskattning av sandbunkrar för smartphone som golfcaddie2011Independent thesis Basic level (degree of Bachelor), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Ett av många nya användningsområden för smartphones är att använda dem som

    caddie på golfbanan. Golfaren kan få hjälp med avståndsuppskattning till intressanta

    punkter på banan genom att dessa punkter programmeras in och jämförs med

    smartphonens inbyggda positioneringssystem. Den här rapporten visar hur det med en

    bildsegmenteringsalgoritm går att slippa det manuella arbetet med att lägga in

    positioner för sandbunkrar på golfbanan. Algoritmen som tagits fram arbetar på

    satellitbilder som smartphonen kan ladda ned via dess Internetanslutning. Golfaren

    kan i ett tänkt scenario ge sig ut på en godtycklig golfbana och få hjälp med

    avståndsbedömning enbart med hjälp av satellitbilder och smartphonens gps. I snitt

    hittar den framtagna segmenteringsalgoritmen cirka 70 % av sandbunkrarna på en

    satellitbild, en siffra som i en verklig applikation skulle behöva ökas och förslag på

    hur detta kan göras ges i slutet av rapporten. Tre olika upplösningar på satellitbilderna

    har utvärderats och testkörts i en nyare smartphone. Även om den högsta

    upplösningen används tar en hel golfbana endast cirka 15 sekunder att segmentera

    vilket bör hinnas med under loppet av en vanlig golfrunda som i regel tar 3 till 5

    timmar.

    I ett vidare perspektiv går det att tänka sig helt andra tillämpningar där det finns

    behov av positionsuppskattning av objekt i en satellitbild i sin smartphone. Det bör på

    ett förhållandevis enkelt sätt gå att utvidga slutsatserna som dragits i rapporten till att

    gälla annat än enbart sandbunkrar, t.ex. sjöar, fält, åkrar och givetvis andra delar av

    golfbanan som vattenhinder och greener.

  • 80.
    Andersson, Mattias
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Dávila, Javier
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Energieffektiva byggmaterials påverkan på radiosignaler: Dämpning av radiosignaler i nya fastigheter2016Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [sv]

    I detta examensarbete undersöks hur nya byggmaterial dämpar radiosignaler samt vilken miljöpåverkan eventuella signalförbättrande lösningar kan ha.

    Miljömedvetenhet och hållbara tekniska lösningar är måsten då planering av nya byggnader görs. Detta sätter stor press på byggföretagen som har stora krav på sig att tänka energieffektivitet och långsiktighet.

    Nya material och byggtekniker syftar till att reducera den mängd energi som krävs för uppvärmning av bostäder. En konsekvens av detta är att radiosignalerna dämpas och att de boende inte har en fullgod mottagning på sina mobiltelefoner inomhus.

    För att komma runt mottagningsproblematiken öppnas ett fönster alternativt balkongdörren för att få acceptabel mottagning. De energiförluster som uppstår på grund av vädring är en viktig parameter att ta i beaktande. En minskning skulle kunna vara ett incitament för en fastighetsägare att vilja satsa på mottagningsförbättrande åtgärder.

    För att bättre få en förståelse för problemen gjordes mätningar på nybyggda hus som ansågs representativa. Resultaten av mätningarna användes senare i matematiska modeller för att analysera och för att skapa förståelse för problemet. Resultatet visar tydlig att den gamla schablonen för förlust på 15 dB inte funkar på nya energieffektiva fastigheter. I rapporten förslås därför ett nytt värde på 23 dB som analysen av det insamlade datat visar. Yttäckningsmodeller gjorda med det nya värdet visat på en minskning av täckningsområdet från basstationen.

  • 81.
    Andersson, Mattias
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori.
    Wyrembelski, R. F.
    Oechtering, Tobias J.
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori.
    Skoglund, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori.
    Polar codes for bidirectional broadcast channels with common and confidential messages2012Inngår i: International Symposium on Wireless Communication Systems (ISWCS), 2012, IEEE conference proceedings, 2012, 1014-1018 s.Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We consider the bidirectional broadcast channel with common and confidential messages. We show that polar codes achieve the capacity of binary input symmetrical bidirectional broadcast channels with confidential messages, if one node's channel is a degraded version of the other node's channel. We also find a new bound on the cardinality of the auxiliary random variable in this setup.

  • 82.
    Andersson, Per
    et al.
    Handelshögskolan, Stockholm School of Economics.
    Markendahl, Jan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, KTH Center för Trådlösa System, Wireless@kth.
    Capabilities for Network Operations and Support of Customers’ Working Processes2007Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this work in progress paper we will discuss company capabilities related to telecom services and how they can be developed or acquired in order to increase the compositeness of the firm. Traditionally, the technical infrastructure and platforms are designed and deployed by the vendors and operators and the role of end-users, private persons or enterprises,  is to accept the offered service, pay and use. This may be a sustainable model when the user requirements are limited to connectivity, communication between persons and internet access, and to delivery of media services where the network acts as a channel. However, we argue that the design and deployment process of telecom services must be changed in order to provide flexible support of customers´ working processes. As a supplier you also have to consider how value is added in the working process of the customer. The full paper will include problem formulation, research questions, theoretical analysis and empirical data from case studies. 

  • 83.
    Andersson Schwarz, Jonas
    et al.
    Södertörns högskola, Institutionen för kultur och lärande, Medie- och kommunikationsvetenskap.
    Palmås, Karl
    Introducing the panspectric challenge: A reconfiguration of regulatory values in a multiplatform media landscape2013Inngår i: Central European Journal of Communication, ISSN 1899-5101, Vol. 6, nr 2, 219-233 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Taking Sweden as a case study, the role of public service broadcasting (PSB) is explored, with a focus on issues of data retention and innovation that accompany web distribution. The issue of predicting audience preferences by means of data retention is investigated, and the related problem of organizational autonomy when interacting with commercial actors in the digital sphere. We hypothesize that previous tendencies towards paternalism might be equally supplemented by tendencies towards so-called “panspectric” surveillance and tracking, given a technological environment where such practices are increasingly common. We argue that the absence of advertising partially helps keep these broadcasters from panspectric temptation. Still, practices such as Facebook integration entail a panspectric element. We ask whether the potential increase in the efficacy of targeting audiences promised by panspectric practices might be offset by its negative impact on civic accountability. Is there a possibility for a “benign,” democratically accountable panspectrocism?

  • 84.
    Andersson, Tommy
    Högskolan i Skövde, Institutionen för kommunikation och information.
    Avvaktande AJAX- anrop: En avlastningsteknik för 3G-nätet2012Independent thesis Basic level (degree of Bachelor), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Den ökade användningen av nätuppkopplade mobilapplikationer har resulterat i en överbelastning i 3G-nätet. Förslag för att avlasta nätet har bland annat varit genom alternativa uppkopplingar, vilket innebär en uppoffring av 3G-nätets tillgänglighet. Detta leder till frågor om andra avlastningsmetoder. Arbetets målsättning var att se hur en applikations datatrafik påverkas av att klassiska intervallanrop ersätts av avvaktande AJAX-anrop. Detta görs genom att implementera respektive anropsmetod i två identiska alfapetapplikationer. Mätdata erhölls genom att låta användare spela längre omgångar av respektive applikation, vilket även genererar realistiska uppdateringar. Resultaten visar att den klientgenererade bandbreddskonsumtionen minskas vid användning av avvaktande AJAX-anrop. Detta gör den, i kontrast med klassiska intervallanrop, till en möjlig avlastningsmetod.

  • 85.
    Andreasson, Carin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Usability Studies of Wireless LAN Systems: *Design of the MUST – Method for Usability Studies and Tests*2001Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This document presents the thesis project “Usability Studies of Wireless Systems, Design of the MUST – Method for Usability Studies and Tests” that was part of the requirements for the degree of Master of Science in Electrical Engineering at the Royal Institute of Technology. The work was carried out at Ericsson WLAN Systems. They develop mobile enablers and had realized the importance of adding input, from the actual users of the systems, into the developing process. The problem was that Ericsson WLAN Systems did not have any kind of strategy for performing usability studies or user tests. The need for a method for usability studies initiated this thesis project.

    The method is called MUST (Method for Usability Studies and Tests) and directs itself towards a project leader and/or usability engineer. It interprets the indistinct and abstract declarations of usability into concrete tools for usability engineering. The method is applied alongside the ordinary development process to enable early and constant focus on usability and to structure the usability engineering. The MUST is divided into five different phases that form a lifecycle, describing the workflow when conducting usability engineering: Know the User, Setting Goals, Prototyping, Testing and User Feedback. Every phase within the MUST lifecycle has a specified goal to be achieved and methods to be used to achieve it. MUST also helps connecting the information flow from product management through software design to support.

    MUST has been tested in parts within this thesis project. Ericsson’s High Security System was put through a Thinking Aloud Test and new and interesting data was gathered through this test, revealing what the users really thought about the product as well as how they actually interacted with it. The results became valuable input to the up-grades of the High Security System.

  • 86.
    Andreev, Sergey D.
    et al.
    Saint-Petersburg State University of Aerospace Instrumentation, Saint-Petersburg, Russia.
    Turlikov, Andrey M.
    Saint-Petersburg State University of Aerospace Instrumentation, Saint-Petersburg, Russia.
    Vinel, Alexey
    Saint-Petersburg State University of Aerospace Instrumentation, Saint-Petersburg, Russia.
    Performance analysis of a high-speed ultra-wideband WPAN MAC2007Inngår i: Proceedings of the 14th International Conference on Analytical and Stochastic Modelling Techniques and Applications: 4 - 6 June 2007, Prague, Czech Republic ; ASMTA 2007 / [ed] Khalid Al-Begain, Armin Heindl & Miklos Telek, Sbr.-Dudweiler: Digitaldruck Pirrot GmbH , 2007, 44-49 s.Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The current paper addresses the problem of the throughput-delay performance of a contemporary WPAN MAC standard. A brief overview of the standard functionality is first presented that allows a system model derivation. Two different acknowledgement policies are described under which the channel operation is considered. Two possible input traffic models are also considered one of them being saturation conditions under which the performance analysis is done that is further verified by means of the simulation. The obtained results show the system behavior as the number of channel users increase and allow the tuning of the protocol parameters to improve the performance.

  • 87.
    Andreev, Sergey D.
    et al.
    Saint-Petersburg State University of Aerospace Instrumentation, Saint-Petersburg, Russia.
    Vinel, Alexey
    Saint-Petersburg State University of Aerospace Instrumentation, Saint-Petersburg, Russia.
    Performance analysis and enhancement of an ultra-wideband WPAN MAC in the presence of noise2007Inngår i: XI International Symposium on Problems of Redundancy in Information and Control Systems, Saint Petersburg, 2007, 117-122 s.Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper addresses the performance evaluation of the contemporary UWB WPAN standard. The basic standard functionality is described for which a system model is derived that accounts for the possible errors due to the background noise. Two realistic scenarios of the saturation conditions and the Bernoulli packet arrivals are considered to calculate the system throughput and the mean initial packet delay. The redundancy-based error detection mechanism that is implemented in the standard is discussed that allows the enhancement of the system performance. The obtained results are compared against the simulation which shows a good accordance with the analytical results and a distinct superiority of the introduced enhancement.

  • 88.
    Andreev, Sergey
    et al.
    Department of Communications Engineering, Tampere University of Technology, Tampere, Finland.
    Galinina, Olga
    Speech Technology Center, St. Petersburg, Russia.
    Vinel, Alexey
    Saint-Petersburg Institute for Informatics and Automation, Russian Academy of Sciences, St. Petersburg, Russia.
    Cross-Layer Channel-Aware Approaches for Modern Wireless Networks2010Konferansepaper (Fagfellevurdert)
  • 89.
    Andreev, Sergey
    et al.
    Department of Communications Engineering, Tampere University of Technology, Finland.
    Galinina, Olga
    Department of Communications Engineering, Tampere University, Finland of Technology.
    Vinel, Alexey
    Department of Communications Engineering, Tampere University, Finland of Technology.
    Performance Evaluation of a Three Node Client Relay System2011Inngår i: International Journal of Wireless Networks and Broadband Technologies, ISSN 2155-6261, Vol. 1, nr 1, 73-84 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, the authors examine a client relay system comprising three wireless nodes. Closed-form expressions for mean packet delay, as well as for throughput, energy expenditure, and energy efficiency of the source nodes are also obtained. The precision of the established parameters is verified by means of simulation.

  • 90.
    Andreev, Sergey
    et al.
    Saint-Petersburg State University of Aerospace Instrumentation, Saint-Petersburg, Russia.
    Saffer, Zsolt
    Budapest University of Technology and Economics, Budapest, Hungary.
    Turlikov, Andrey
    Saint-Petersburg State University of Aerospace Instrumentation, Saint-Petersburg, Russia.
    Vinel, Alexey
    Saint-Petersburg Institute for Informatics and Automation, Russian Academy of Sciences, Saint-Petersburg, Russia.
    Overall Delay in IEEE 802.16 with Contention-Based Random Access2009Inngår i: / [ed] K. Al Begain, D. Fiems, G. Horvath, Heidelberg: Springer, 2009, 89-102 s.Konferansepaper (Fagfellevurdert)
  • 91.
    Andreev, Sergey
    et al.
    Department of Communications Engineering, Tampere University of Technology, Tampere, Finland.
    Saffer, Zsolt
    Budapest University of Technology and Economics, Budapest, Hungary.
    Turlikov, Andrey
    Saint-Petersburg State University of Aerospace Instrumentation, Saint-Petersburg, Russia.
    Vinel, Alexey
    Saint-Petersburg Institute for Informatics and Automation, Russian Academy of Sciences, Saint-Petersburg, Russia.
    Upper Bound on Overall Delay in Wireless Broadband Networks with Non Real-Time Traffic2010Konferansepaper (Fagfellevurdert)
  • 92.
    Andreev, Sergey
    et al.
    St. Petersburg State University of Aerospace Instrumentation, Bolshaya Morskaya street, 67, 190000, St. Petersburg, Russian Federation.
    Turlikov, Andrey
    St. Petersburg State University of Aerospace Instrumentation, Bolshaya Morskaya street, 67, 190000, St. Petersburg, Russian Federation.
    Vinel, Alexey
    St. Petersburg State University of Information Technologies, Mechanics and Optics, Vasilievsky Island, Birjevaja Linija, 4, 199034, St. Petersburg, Russian Federation.
    Contention-Based Polling Efficiency in Broadband Wireless Networks2008Inngår i: Analytical and Stochastic Modeling Techniques and Applications: 15th International Conference, ASMTA 2008 Nicosia, Cyprus, June 4-6, 2008 Proceedings / [ed] Khalid Al-Begain, Armin Heindl, Miklós Telek, Berlin: Springer Berlin/Heidelberg, 2008, 295-309 s.Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper addresses the performance of the contention-based polling techniques at the bandwidth reservation stage of IEEE 802.16 standard. A general proposition is proved, which establishes that the grouping of users in the random multiple access system does not change its capacity. Broadcast and multicast polling mechanisms are then considered, for which the throughput and the rate of the truncated binary exponential backoff algorithm are calculated for the lossy and the lossless system types, respectively. It is shown, that subject to proper optimization the performance of the aforementioned algorithm is the same for both system types. The efficiency of the symmetric user grouping is finally studied, which demonstrates that a negligible performance gain may be achieved for the cost of the increased IEEE 802.16 overhead.

  • 93.
    Andreev, Sergey
    et al.
    Saint-Petersburg State University of Aerospace Instrumentation, Saint-Petersburg, Russia.
    Turlikov, Andrey
    Saint-Petersburg State University of Aerospace Instrumentation, Saint-Petersburg, Russia.
    Vinel, Alexey
    Saint-Petersburg Institute for Informatics and Automation, Russian Academy of Sciences, Saint-Petersburg, Russia.
    Symmetric User Grouping for Multicast and Broadcast Polling in IEEE 802.16 Networks2008Inngår i: Selected Lectures on Multiple Access and Queueing Systems: Revised Selected Papers from International Workshop on Multiple Access Communications - MACOM-2008 (16-17 June 2008, Saint-Petersburg) / [ed] Vladimir Vishnevsky, Alexey Vinel, Yevgeni Koucheryavy & Dirk Staehle, Saint-Petersburg: Saint-Petersburg State University of Aerospace Instrumentation , 2008, 52-62 s.Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper we address the bandwidth reservation in IEEE 802.16 standard via multicast and broadcast polling mechanisms. It is shown that symmetric user grouping with the same QoS requirements does not change the capacity of the random multiple access system. Binary exponential backoff protocol is then investigated as it is standardized for both multicast and broadcast polling. We establish that symmetric user grouping does not essentially increase the performance of this protocol.

  • 94.
    Andreev, Sergey
    et al.
    Saint-Petersburg State University of Aerospace Instrumentation, Saint-Petersburg, Russia.
    Vinel, Alexey
    Saint-Petersburg State University of Aerospace Instrumentation, Saint-Petersburg, Russia.
    Gilbert-Elliot Model Parameters Derivation for the IEEE 802.11 Wireless Channel2007Inngår i: Distributed Computer and Communication Networks. Theory and Applications: Proceedings of the International Workshop. Vol.1. Moscow, Russia, September 10-12, 2007, Moscow: Institute for Information Transmission Problems (Kharkevich Institute) , 2007, 101-107 s.Konferansepaper (Fagfellevurdert)
  • 95. Andreou, Charalambos
    et al.
    Paccagnella, A.
    González-Castaño, D.M.
    Gómez, F.
    Liberali, V.
    Prokofiev, Alexander V.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Calligaro, C.
    Javanainen, A.
    Virtanen, A.
    Nahmad, D.
    Georgiou, J.
    A Subthreshold, Low-Power, RHBD Reference Circuit, for Earth Observation and Communication Satellites2015Inngår i: Circuits and Systems (ISCAS), 2015 IEEE International Symposium on, 2015, 2245-2248 s.Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A low-power, wide temperature range, radiation tolerant CMOS voltage reference is presented. The proposed reference circuit exhibits a voltage deviation of 0.8mV for 3-MeV protons total ionization dose of 2Mrad and a voltage deviation of 3.8mV for 10-keV X-rays total ionization dose of 4Mrad while being biased at the nominal supply voltage of 0.75V during X-ray irradiation. In addition, the circuit consumes only 4 mu W and exhibits a measured Temperature Drift of 15ppm/degrees C for a temperature range of 190 degrees C (-60 degrees C to 130 degrees C) at the supply voltage of 0.75V. It utilizes only CMOS transistors, operating in the subthreshold regime, and poly-silicon resistors without using any diodes or external components such as compensating capacitors. The circuit is radiation hardened by design (RHBD), it was fabricated using TowerJazz Semiconductor's 0.18 mu m standard CMOS technology and occupies a silicon area of 0.039mm(2). The proposed voltage reference is suitable for high-precision and low-power space applications.

  • 96.
    André, Johan
    KTH, Tidigare Institutioner, Teleinformatik.
    Automated test procedure for GSM Over-The-Air SIM file management1999Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Developments of new Servers for Over-the-Air SIM file management and SIM Toolkit applications require a comprehensive test procedure to verify their operation. The goal of this Master Thesis has been to improve the existing test procedure and if possible develop a new procedure that could make the tests more efficient.

    Measurements showed that the most time consuming parts of the existing procedure were latencies in the GSM network and manual operations.

    Two major questions had to be handled if it was possible to fully automate the manual test procedure and if an application that reduced the latencies in GSM network would be efficient. This report indicates that it wasn't worth the effort to introduce such an automated test procedure since the extra workload was not in proportion to the benefits.

    In order to improve the performance due to the latencies in the GSM network an application that reduced this latency was implemented. This application made it possible to transfer Short Messages directly to the SIM-card without passing through the GSM network or through the mobile phone. With the new procedure the time for existing test procedure was reduced by as much as 65%.

  • 97.
    Angelakis, Vangelis
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Avgouleas, Ioannis
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Pappas, Nikolaos
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Fitzgerald, Emma
    Lund University, Sweden.
    Yuan, Di
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten. University of Maryland, MD 20742 USA.
    Allocation of Heterogeneous Resources of an IoT Device to Flexible Services2016Inngår i: IEEE Internet of Things Journal, ISSN 2327-4662, Vol. 3, nr 5, 691-700 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Internet-of-Things (IoT) devices can be equipped with multiple heterogeneous network interfaces. An overwhelmingly large amount of services may demand some or all of these interfaces available resources. Herein, we present a precise mathematical formulation of assigning services to interfaces with heterogeneous resources in one or more rounds. For reasonable instance sizes, the presented formulation produces optimal solutions for this computationally hard problem. We prove the NP-completeness of the problem and develop two algorithms to approximate the optimal solution for big instance sizes. The first algorithm allocates the most demanding service requirements first, considering the average cost of interfaces resources. The second one calculates the demanding resource shares and allocates the most demanding of them first by choosing randomly among equally demanding shares. Finally, we provide simulation results giving insight into services splitting over different interfaces for both cases.

  • 98.
    Angelakis, Vangelis
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Avgouleas, Ioannis
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Pappas, Nikolaos
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Yuan, Di
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Flexible allocation of heterogeneous resources to services on an IoT device2015Inngår i: 2015 IEEE Conference on Computer Communications Workshops (INFOCOM WKSHPS), Institute of Electrical and Electronics Engineers (IEEE), 2015, 99-100 s.Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In the Internet of Things (IoT), devices and gateways may be equipped with multiple, heterogeneous network interfaces which should be utilized by a large number of services. In this work, we model the problem of assigning services' resource demands to a device's heterogeneous interfaces and give a Mixed Integer Linear Program (MILP) formulation for it. For meaningful instance sizes the MILP model gives optimal solutions to the presented computationally-hard problem. We provide insightful results discussing the properties of the results on the properties of the derived solutions with respect to the splitting of services to different interfaces.

  • 99.
    Angelakis, Vangelis
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Efrat, Alon
    University of Arizona, AZ 85721 USA.
    Packer, Eli
    IBM Research Haifa, Israel.
    Polishchuk, Valentin
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Sedov, Leonid
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    BBTM: New life for old ATM2016Inngår i: 2016 IEEE/AIAA 35TH DIGITAL AVIONICS SYSTEMS CONFERENCE (DASC), IEEE , 2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper investigates algorithmic questions related to the possibility of managing UAV traffic with beacon-based navigation, which we dub BBTM - Beacon-Based Traffic Management. The specific problem addressed is: How to install the minimum number of beacons in a mountainous terrain to ensure connectivity among a given set of UAS terminals on the terrain? BBTM is relevant for low-cost UAVs operating in remote areas not on time-critical missions, and may also be used as a backup system for better-equipped UAS in case the precise positioning or control information is lost, spoofed or jammed. We give algorithms for the beacon tower placement and evaluate their performance both on synthetic and real-world terrain data; the experiments suggest that our solutions can be used to efficiently quantify costs of establishing direct-visibility routing networks for UAS management.

  • 100.
    Angeles Piña, Carlos
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Distribution of Context Information using the Session Initiation Protocol (SIP)2008Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Context-aware applications are applications that exploit knowledge of the situation of the user (i.e. the user’s context) to adapt their behavior, thus helping the user achieve his or her daily tasks. Today, the transfer of context information needs to take place over unreliable and dynamically changing networks. Moreover context information may be produced in different devices connected to different networks. These difficulties have limited the development of context-aware applications. This thesis presents a context distribution method exploiting the event notification mechanisms of the Session Initiation Protocol (SIP), aiming to provide access to context information regardless of where it is produced.

    The context distribution component presented in this thesis uses SIP for Instant Messaging and Presence Leveraging Extensions (SIMPLE) to enable context sharing by using a SIP presence server, specifically the SIP Express Router (SER) and its presence module. This context distribution component allows distribution of context information in both synchronous and asynchronous mode. The distribution mode depends on the application requirements for context distribution, as well as the nature and characteristics of the contextinformation. In this thesis, based on system scalability, the user’s mobility, and latency - recommendations are given about in which situations each mode is more suitable for distributing context information.

    The system was evaluated using a load generator. The evaluation revealed that the server is highly scalable. The response time for synchronous retrieval of context information is nearly constant, while in asynchronous mode the time to process a subscription increases with the amount of information in the database regarding previous subscriptions. Notifications are sent at a regular rate (≈2800 notifications per second); however there is a purposely random delay (0 to 1 second), between an update of context information (i.e. receipt of a publish message) and the start of notifications to subscribed users.

    The requirements of the context-aware applications using the distribution component, such as response time, have to be taken into account when deciding upon the mode of context distribution for each application. This thesis provides some empirical data to help an application developer make this selection.

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