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  • 3051.
    Vu Hong, Linh
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    DNS Traffic Analysis for Network-based Malware Detection2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Botnets are generally recognized as one of the most challenging threats on the Internet today. Botnets have been involved in many attacks targeting multinational organizations and even nationwide internet services. As more effective detection and mitigation approaches are proposed by security researchers, botnet developers are employing new techniques for evasion. It is not surprising that the Domain Name System (DNS) is abused by botnets for the purposes of evasion, because of the important role of DNS in the operation of the Internet. DNS provides a flexible mapping between domain names and IP addresses, thus botnets can exploit this dynamic mapping to mask the location of botnet controllers. Domain-flux and fast-flux (also known as IP-flux) are two emerging techniques which aim at exhausting the tracking and blacklisting effort of botnet defenders by rapidly changing the domain names or their associated IP addresses that are used by the botnet. In this thesis, we employ passive DNS analysis to develop an anomaly-based technique for detecting the presence of a domain-flux or fast- flux botnet in a network. To do this, we construct a lookup graph and a failure graph from captured DNS traffic and decompose these graphs into clusters which have a strong correlation between their domains, hosts, and IP addresses. DNS related features are extracted for each cluster and used as input to a classication module to identify the presence of a domain-flux or fast-flux botnet in the network. The experimental evaluation on captured traffic traces veried that the proposed technique successfully detected domain-flux botnets in the traces. The proposed technique complements other techniques for detecting botnets through traffic analysis.

  • 3052.
    Vu, Minh thanh
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Oechtering, Tobias J.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Lossy distributed storage with limited failure loss2015In: Proceedings of the International Symposium on Wireless Communication Systems, VDE Verlag GmbH, 2015, p. 191-195Conference paper (Refereed)
    Abstract [en]

    In this paper a successive refinement problem is considered where decoders can access only distributed storage nodes, subject to an additional constraint on the loss of information if failures happen. We characterize the optimal tradeoff for a given a distortion tuple and an equivocation constraint between storage nodes. A binary example is provided to illustrate the trade-off between the loss of information constraint and the corresponding achievable rate region.

  • 3053.
    Vukadinovic, Vladimir
    et al.
    Disney Research Zürich.
    Helgason, Ólafur
    KTH, School of Electrical Engineering (EES), Communication Networks. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Karlsson, Gunnar
    KTH, School of Electrical Engineering (EES), Communication Networks. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    An analytical model for pedestrian content distribution in a grid of streets2013In: Mathematical and computer modelling, ISSN 0895-7177, E-ISSN 1872-9479, Vol. 57, no 11-12, p. 2933-2944Article in journal (Refereed)
    Abstract [en]

    Mobile communication devices may be used for spreading multimedia data without support of an infrastructure. Such a scheme, where the data is carried by people walking around and relayed from device to device by means of short range radio, could potentially form a public content distribution system that spans vast urban areas. The transport mechanism is the flow of people and it can be studied but not engineered. We study the efficiency of pedestrian content distribution by modeling the mobility of people moving around in a city, constrained by a given topology. The model is supplemented by simulation of similar or related scenarios for validation and extension. The results show that contents spread well with pedestrian speeds already at low arrival rates into a studied region. Our contributions are both the queuing analytic model that captures the flow of people and the results on the feasibility of pedestrian content distribution.

  • 3054.
    Vuković, Ognjen
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Data Integrity and Availability in Power System Communication Infrastructures2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Society is increasingly dependent on the proper functioning of electric power systems. Today's electric power systems rely heavily on information and networking technology in order to achieve efficient and secure operation. Recent initiatives to upgrade power systems into smart grids target an even tighter integration with information and communication technologies in order to enable the integration of renewable energy sources, local and bulk generation and demand response. Therefore for a proper functioning of smart grids, it is essential that the communication network is secure and reliable both in the face of network failures and in the face of attacks. This thesis contributes to improving the security of power system applications against attacks on the communication infrastructure. The contributions lie in two areas.

    The first area is the interaction of network and transport layer protocols with power system application layer security. We consider single and multi-area power system state estimation based on redundant telemetry measurements. The state estimation is a basis for a set of applications used for information support in the control center, and therefore its security is an important concern. For the case of single-area state estimation, we look at the security of measurement aggregation over a wide area communication network. Due to the size and complexity of power systems, it can be prohibitively expensive to introduce cryptographic security in every component of the communication infrastructure. Therefore, we investigate how the application layer logic can be leveraged to optimize the deployment of network, transport and application layer security solutions. We define security metrics that quantify the importance of particular components of the network infrastructure. We provide efficient algorithms to calculate the metrics, and that allow identification of the weakest points in the infrastructure that have to be secured. For the case of multi-area state estimation, we look at the security of data exchange between the control centers of neighboring areas. Although the data exchange is typically cryptographically secure, the communication infrastructure of a control center may get compromised by a targeted trojan that could attack the data before the cryptographic protection is applied or after it is removed. We define multiple attack strategies for which we show that they can significantly disturb the state estimation. We also show a possible way to detect and to mitigate the attack.

    The second area is a study of the communication availability at the application layer. Communication availability in power systems has to be achieved in the case of network failures as well as in the case of attacks. Availability is not necessarily achieved by cryptography, since traffic analysis attacks combined with targeted denial-of-service attacks could significantly disturb the communication. Therefore, we study how anonymity networks can be used to improve availability, which comes at the price of increased communication overhead and delay. Because of the way anonymity networks operate, one would expect that availability would be improved with more overhead and delay. We show that surprisingly this is not always the case. Moreover, we show that it is better to overestimate than to underestimate the attacker's capabilities when configuring anonymity networks.

  • 3055.
    Vuković, Ognjen
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Dán, György
    KTH, School of Electrical Engineering (EES), Communication Networks.
    On the Security of Distributed Power System State Estimation under Targeted Attacks2013In: Proceedings of the 28th Annual ACM Symposium on Applied Computing, 2013, p. 666-672Conference paper (Refereed)
    Abstract [en]

    State estimation plays an essential role in the monitoring and control of power transmission systems. In modern, highly inter-connected power systems the state estimation should be performed in a distributed fashion and requires information exchange between the control centers of directly connected systems. Motivated by recent reportson trojans targeting industrial control systems, in this paper we investigate how a single compromised control center can affect the outcome of distributed state estimation. We describe five attack strategies, and evaluate their impact on the IEEE 118 benchmark power system. We show that that even if the state estimation converges despite the attack, the estimate can have up to 30% of error, and bad data detection cannot locate theattack. We also show that if powerful enough, the attack can impede the convergence of the state estimation, and thus it can blind the system operators. Our results show that it is important to provide confidentiality for the measurement data in order to prevent the most powerful attacks. Finally, we discuss a possible way to detect and to mitigate these attacks.

  • 3056.
    Vuković, Ognjen
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Dán, György
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Karlsson, Gunnar
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Mitigating Denial of Service Attacks using Anonymity Networks: Relationship Anonymity-Communication Overhead Trade-offManuscript (preprint) (Other academic)
    Abstract [en]

    Denial-of-service attacks are a significant threat to mission critical communication infrastructures, e.g., to industrial control systems. They are relatively easy to perpetrate, as an attacker that has access to communication links or equipment could observe the source and destination addresses for every message, and can identify and discard the messages exchanged between particular communication participants. Mix networks and anonymity networks could render these attacks more difficult by providing anonymous communication via relaying. Nevertheless, relaying introduces overhead and increases the end-to-end message delivery delay, which in practice must often be low. Hence, an important question is how to optimize anonymity for limited overhead and delay. In this paper we address this question by studying two anonymity networks: MCrowds, an extension of Crowds, which provides unbounded communication delay and Minstrels, which provides bounded communication delay. We derive exact and approximate analytical expressions for the relationship anonymity for these systems. Using MCrowds and Minstrels we show that, contrary to intuition, increased overhead does not always improve anonymity. We investigate the impact of the system's parameters on anonymity and on the optimal anonymity network parameters, and the sensitivity of anonymity to the misestimation of the number of attackers.

  • 3057.
    Vuković, Ognjen
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Dán, György
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Karlsson, Gunnar
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Traffic Analysis Attacks in Anonymity Networks: Relationship Anonymity-Overhead Trade-off2013Report (Other academic)
    Abstract [en]

    Mix networks and anonymity networks provide anonymous communication via relaying, which introduces overhead and increases the end-to-end message delivery delay. In practice overhead and delay must often be low, hence it is important to understand how to optimize anonymity for limited overhead and delay. In this work we address this question under passive traffic analysis attacks, whose goal is to learn the traffic matrix. For our study, we use two anonymity networks: MCrowds, an extension of Crowds, which provides unbounded communication delay and Minstrels, which provides bounded communication delay. We derive exact and approximate analytical expressions for the relationship anonymity for these systems. Using MCrowds and Minstrels we show that, contrary to intuition, increased overhead does not always improve anonymity. We investigate the impact of the system's parameters on anonymity, and the sensitivity anonymity to the misestimation of the number of attackers.

  • 3058.
    Waddington, Simon
    et al.
    King's College London, UK.
    Hedges, Mark
    King's College London, UK.
    Riga, Marina
    CERTH, Thessaloniki, Greece.
    Mitzias, Panagiotis
    CERTH, Thessaloniki, Greece.
    Kontopoulos, Efstratios
    CERTH, Thessaloniki, Greece.
    Kompatsiaris, Ioannis
    CERTH, Thessaloniki, Greece.
    Vion-Dury, Jean-Yves
    XRCE, Grenoble, France.
    Lagos, Nikolaos
    XRCE, Grenoble, France.
    Darányi, Sándor
    University of Borås, Faculty of Librarianship, Information, Education and IT.
    Corubolo, Fabio
    University of Liverpool, UK.
    Muller, Christian
    BUSOC, Belgium.
    McNeill, John
    Tate Galleries, London, UK.
    PERICLES – Digital Preservation through Management of Change in Evolving Ecosystems.2016In: The Success of European Projects Using New Information and Communication Technologies / [ed] Hamriouni, S., Setubal, Portugal, 2016, p. 51-74Conference paper (Refereed)
    Abstract [en]

    Management of change is essential to ensure the long-term reusabilityof digital assets. Change can be brought about in many ways, includingthrough technological, user community and policy factors. Motivated by casestudies in space science and time-based media, we consider the impact ofchange on complex digital objects comprising multiple interdependent entities,such as files, software and documentation. Our approach is based on modellingof digital ecosystems, in which abstract representations are used to assess risksto sustainability and support tasks such as appraisal. The paper is based onwork of the EU FP7 PERICLES project on digital preservation, and presentssome general concepts as well as a description of selected research areas underinvestigation by the project.

  • 3059.
    Wagner, Ben
    et al.
    European University Viadrina.
    Mindus, Patricia
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Arts, Department of Philosophy.
    Multistakeholder Governance and Nodal Authority – Understanding Internet Exchange Points2015Report (Refereed)
    Abstract [en]

    This case study considers Internet exchange points (IXPs) as an example of governance processes in action. Internet exchange points are the points of connection between different Internet networks, which enable different networks to exchange traffic at a shared facility without cost to either party through a process known as “peering”. Three different IXP governance models representing large and influential IXPs are compared: the DE-CIX in Frankfurt, CAIX in Cairo, and KIXP in Nairobi. DE-CIX, the largest IXP in the world, is a subsidiary of the German Internet trade association eco, and is thus “owned” by the Internet industry in Germany. Though well functioning, this has meant that key stakeholder groups such as civil society, and the academic and technical communities are excluded from participating in discussions over policy decisions. In contrast, the Cairo Internet Exchange Point (CAIX) is run by a public authority, the Egyptian Ministry of Communications and Information Technology. Though it is governed by a broad set of stakeholders including private sector, government, and civil society representatives, its decision-making processes are somewhat opaque. Lastly, KIXP was founded by a Kenyan network engineer and is governed by a local trade association. While set up with multistakeholder coordination under the leadership of the private sector, its dayto-day operations and governance fall under private sector control. By tracing out the plurality of models used for IXP governance and comparing the processes of developing peering relationships, this case provides unique lessons for the governance process, particularly surrounding trade-offs between inclusiveness and effectiveness.

  • 3060.
    Wahlgren, Rune
    KTH, Superseded Departments, Teleinformatics.
    Broadcast of financial information : How to broadcast web information to wireless users1996Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Mobile or wireless information retrieval is an area that is expected to increased dramatically in near future. In order to meet the demand for broadband of content, and to learn how these systems can used for publishing, Bonnier is participating in the On the Move Project. But, the On the Move project intends to use UMTS. As this systems is not yet available, Bonnier has initiated a cooperation with Teracom in the MEMO project. The MEMO project will develop a common platform for an wireless asymmetric communication system that will consist of a broadband downstream channel (DAB) and narrowband upstream channels (GSM). They have also develop a framework of an architecture and a interface to the DAB channel for this purpose.

    Wireless asymmetric communication systems utelise the nature of an information retrieval session very well, because the request from the clients are very modest regarding demanded bandwidth in contrast to the server response which usually demand much bandwidth for downloading the requested information to the client.

    In my thesis project I have developed and implemented three different software's that will fit in the MEMO architecture and offer the user the specified functionality. That is, the user shall be able to retrieve information in broadcast and/or on-demand mode. The software's developed is a client part which will be running on the mobile host, a server software which will serve the client with the requested information, and a broadcast software which enables the content provider to broadcast specific content in their service. The broadcast channel is developed by Teracom.

    The result that this project has achieved is, first some measurement on a model of the system that shows the benefits with broadcast mode in the system. The test also showed that introduction of caching in the system considerably reduce the latency for the client in retrieving information. Second, their have been some needs outlined that the content provider have on these kinds on systems, and how the content provider shall construct a service that are intended for these kinds of systems.

  • 3061.
    Wahlund, Thomas
    KTH, Superseded Departments, Teleinformatics.
    Using Concentrators to build a cost effective network1995Independent thesis Advanced level (degree of Master (Two Years)), 12 credits / 18 HE creditsStudent thesis
    Abstract [en]

    The intention with this project was to examine the way FTNS Nordic is using concentrators as network nodes to build a cost effective network. The strategy for where and when to place out new concentrators in the network was also analysed. In his presentation, Thomas will describe the different ways to use concentrators in the network, in order to make network subscribers share bandwidth between the point of access and the network switches. He will also describe a process to analyse the costs involved in placing out new concentrators. Some methods on how to calculate the cost of bandwidth according to the price list for leased lines, and how to calculate the optimised placement (according to the cost of lines) of new concentrators are also presented.

  • 3062.
    Walldén, Marcus
    et al.
    KTH, School of Information and Communication Technology (ICT).
    Özkan, Aylin
    KTH, School of Information and Communication Technology (ICT).
    A graph database management system for a logistics-related service2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Higher demands on database systems have lead to an increased popularity of certain database system types in some niche areas. One such niche area is graph networks, such as social networks or logistics networks. An analysis made on such networks often focus on complex relational patterns that sometimes can not be solved efficiently by traditional relational databases, which has lead to the infusion of some specialized non-relational database systems. Some of the database systems that have seen a surge in popularity in this area are graph database systems.

    This thesis presents a prototype of a logistics network-related service using a graph database management system called Neo4j, which currently is the most popular graph database management system in use. The logistics network covered by the service is based on existing data from PostNord, Sweden’s biggest provider of logistics solutions, and primarily focuses on customer support and business to business.

    By creating a prototype of the service this thesis strives to indicate some of the positive and negative aspects of a graph database system, as well as give an indication of how a service using a graph database system could be created.

    The results indicate that Neo4j is very intuitive and easy to use, which would make it optimal for prototyping and smaller systems, but due to the used evaluation method more research in this area would need to be carried out in order to confirm these conclusions.

  • 3063.
    Walters, Jamie
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Kanter, Theo
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Evolving Presentity-Based Context Schemas by Estimating Context Proximity2012In: Lecture Notes of the Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering, Springer, 2012, p. 137-152Conference paper (Refereed)
    Abstract [en]

    The definition of what constitutes context proximity has remained largely unexplored but accepted as being a fundamental issue towards realising an architecture of connected things. Existing solutions aimed at enabling context awareness are often undermined by their dependencies on centralized architectures limited with respect to their scalability. Our previous work proposed the use of the so called Context Schema; an encapsulated representation of the information points constituting the context of a presentity. Building such a schema requires support for determining set members limited by some metric; a proximity metric. In this paper, we propose an algorithm for estimating the context proximity among presentities, enabling complete schemata of entities relevant to, and expressing the current context of a presentity. Secondly we propose an extension of a gossiping algorithm to optimize the ability create schemata as one traverses a vast and dynamic connected things infrastructure. © 2012 ICST Institute for Computer Science, Social Informatics and Telecommunications Engineering.

  • 3064.
    Waltersson, Roland
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Middleware for adaptive network connectivity2006Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As the coverage of modern wireless technologies expands, today’s mobile phones and PDAs often have a range of heterogeneous networks to which they may connect. It would benefit mobile applications to use the network which best corresponds to its need. However, making the handovers between networks transparent to allow communication sessions to survive is not trivial as the TCP/IP suite, used by most networking applications today, was initially not designed with mobility in mind.

    A Vinnova founded research project at Saab (together with associates1) has found that it could prove advantageous to monitor network quality together with the application’s needs and make intelligent decisions regarding what network to use. An algorithm for network classification and evaluation has been proposed.

    This thesis examined prerequisites and methods for implementing adaptive network connectivity through transparent handovers for mobile devices, resulting in a tentative model to demonstrate the mentioned research results. The prototype, implemented as a user space middleware, utilizes UDP encapsulation and a per-packet basis link evaluation, resulting in small overhead and fast context adaptation. Link monitoring ensures that server and clients are constantly updated about network quality and availability.

    The prototype yielded transparent handovers between networks, with short handover delays, at the cost of reduced performance for fast networks.

    1 Blekinge Institute of Technology, Swedish National Testing and Research Institute, and SwedishRoad Administration

  • 3065.
    Wang, Chao
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Xiao, Ming
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Rasmussen, Lars
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Performance analysis of coded secondary relaying in overlay cognitive radio networks2012In: 2012 IEEE Wireless Communications and Networking Conference, WCNC, IEEE Communications Society, 2012, p. 294-299Conference paper (Refereed)
    Abstract [en]

    We study the error and diversity-multiplexing tradeoff (DMT) performance of a (secondary) multi-user relay network, where a class of finite field network codes are applied in the relays to efficiently provide spatial diversity. To eliminate spectral efficiency loss induced by half-duplex limitation we adopt the cognitive radio overlay spectrum sharing concept and consider aligning the relays' operation with that of a primary system. To compensate the interference introduced by the secondary relaying, the secondary destination also transmits the primary signals to boost the signal power of the primary system. We also consider exploiting Automatic Repeat Request (ARQ) feedback signals from the secondary destination to minimize the energy consumption of the secondary system. In addition, by allowing multiple secondary sources to transmit non-orthogonally, the performance can be further enhanced.

  • 3066.
    Wang, Guojun
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Optimizing System Level Testing of Evolved Packet Gateway2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The goal of this thesis project is to improve industrial system testing efficiency. The thesis is mainly focused on the field of telecommunication. Testing is one of the most important steps before selling a product to customers and testing is also an important component of after sale maintenance. The work load for testers can be decreased and more projects could be carried out in parallel, if the testing efficiency can be improved.

    The thesis project is carried out within the Ericsson Product Development Unit (PDU) Packet Core System Test section. The goal is to improve the system testing efficiency of the Evolved Packet Gateway, as system testing has gradually become one of the bottle necks for the whole product release. Ericsson wants to accelerate its pace in releasing new products to the market and releasing new software to their customers. An initial investigation was made to get a clear view about how the complete system testing procedure is currently carried out and then, an analysis was made based on this information. Ideas were collected for a proposed new implementation and finally a prototype for the most useful ideas was developed and evaluated to show how the system testing efficiency can be improved.

    Finally, these ideas were proved to be valuable for Ericsson PDU Packet Core System Test section and two of them have been adopted and are already under developing.

  • 3067.
    Wang, Huajun
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Hossain, Masum M.Aftab
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Cloud RAN architectures with optical and mm-Wave transport technologies2017In: 2017 19th International Conference on Transparent Optical Networks (ICTON), IEEE Computer Society, 2017, article id 8025007Conference paper (Refereed)
    Abstract [en]

    Cloud RAN has been regarded as a promising architecture for 5G mobile networks in terms of combination of implementing the very tight radio coordination schemes and sharing baseband processing and cooling system resources. However, the high capacity and stringent delay requirement for the fronthaul, the segment of the network between Baseband Units (BBU) and Remote Radio Heads (RRH) is one of the biggest barriers to larger deployments. To relax these constraints, physical layer functions can be split and centralized partially. In this paper, under one specific case scenario with the fixed number of LTE base stations, we calculate the transport capacity requirement for different physical layer function splitting solutions and adopt different transport technologies, i.e. Ethernet Passive Optical Network (EPON), Time-Wavelength Division Multiplexing PON, (TWDM-PON) and millimeter Wave (mm-Wave). We develop an end-to end power consumption model where the total power consumption is calculated by adding up the power utilized by RRHs, transport network and baseband processing. TWDM-PON shows better energy performance as fronthaul network when the capacity requirement is high, compared to EPON. The mm-Wave fronthaul is a better solution in terms of saving fiber and flexibility of deployment but comparatively more energy consuming.

  • 3068. Wang, J.
    et al.
    Ebrahimi, Masoumeh
    KTH, School of Information and Communication Technology (ICT), Electronics, Integrated devices and circuits. University of Turku, Finland.
    Huang, L.
    Li, Q.
    Li, G.
    Jantsch, A.
    Minimizing the system impact of router faults by means of reconfiguration and adaptive routing2017In: Microprocessors and microsystems, ISSN 0141-9331, E-ISSN 1872-9436, Vol. 51, p. 252-263Article in journal (Refereed)
    Abstract [en]

    To tolerate faults in Networks-on-Chip (NoC), routers are often disconnected from the NoC, which affects the system integrity. This is because cores connected to the disabled routers cannot be accessed from the network, resulting in loss of function and performance. We propose E-Rescuer, a technique offering a reconfigurable router architecture and a fault-tolerant routing algorithm. By taking advantage of bypassing channels, the reconfigurable router architecture maintains the connection between the cores and the network regardless of the router status. The routing algorithm allows the core to access the network when the local router is disabled.Our analysis and experiments show that the proposed technique provides 100% packet delivery in 100%, 92.56%, and 83.25% of patterns when 1, 2 and 3 routers are faulty, respectively. Moreover, the throughput increases up to 80%, 46% and 33% in comparison with FTLR, HiPFaR, and CoreRescuer, respectively.

  • 3069.
    Wang, Jiacheng
    et al.
    University of Skövde, School of Engineering Science.
    Domingos, Luzaisso
    University of Skövde, School of Engineering Science.
    Developing of Data Logging System for Flow Test Station in Industrial Laboratory2016Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    CEJN is a leading transnational company with long history and professional background providing high-tech quick connect products in global market. The headquarters of the com-pany in Skövde, Sweden, is the birthplace and core location of the entire corporation. In the headquarters, the engineer tests their products at their flow test laboratory. In the laboratory, there are flow test stations for all product ranges. Within them, the most basic are flow test benches for air, water and hydraulic oil products. The flow test benches are aim to test the products under International/Swedish standard conditions to determine the performance.

    This project is aimed in upgrading the test benches by engineering both hardware and soft-ware, to achieve higher level of automation of the data logging system used in the lab. All three test benches were designed and installed following requirements in corresponding in-ternational standards. The principles of testing are similar, but they are not developed from the same era, and the automation level of each test bench differs. As a result, the need of up-grading in the benches is different.

    In the laboratory, the recorded test results are reorganized and processed by a report genera-tor developed on Microsoft Excel. The Excel report generator is used for organize test results, calibrate the deviation of the instruments, calculate the flow coefficient of the product, gener-ate performance diagrams of the products, generate test reports for different purpose of use, and save the test data and results on the server of the company.

    Above all, an upgrade of the data logging system for the three flow test benches was needed. Depending on the conditions of each test bench, the project is implemented and designed the following three parts:

    • A hardware upgrading (flow rate computer) for the air flow test benchA new signal indicating device for replacing the old flow rate computer is purchased from Italy by the company. The new instrument contains filter function to stabilize the flow rate value.

    • A software upgrading (Excel report generator) for all the test benchesVisual Basic for Applications (VBA) programming language is used for developing functions such as data communication, signal decoding and user interface developing in Excel.

    • Develop of an automated data visualizing system for the air flow test benchData communication from the new instrument to a PC through serial port and Mod-bus RTU interface is established. The data visualizing function is compiled in the Ex-cel report generator for the air flow test, realized by VBA programming.

  • 3070.
    Wang, Jiaheng
    et al.
    National Mobile Communications Research Laboratory, Southeast University, Nanjing, China .
    Bengtsson, Mats
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Simplified alternating optimization for robust MMSE MIMO transceiver2011In: International Conference on Wireless Communications and Signal Processing (WCSP), 2011, IEEE conference proceedings, 2011Conference paper (Refereed)
    Abstract [en]

    We consider a worst-case robust transceiver design for multiple-input multiple-output (MIMO) channels, under the minimum mean square error (MMSE) criterion, to combat against the imperfection of channel state information (CSI). The joint robust transceiver design is formulated as a minimax problem. We show that for a given precoder (equalizer), the optimal robust equalizer (precoder) is obtained in a semi-closed form by channel diagonalization. Thus, a joint robust transceiver can be efficiently achieved by alternately optimizing the equalizer and precoder, where in each iteration only a power allocation problem is to be solved. We also propose efficient algorithms to solve the power allocation problems in each iteration.

  • 3071.
    Wang, K
    et al.
    Acreo Swedish ICT AB.
    Hussein, M
    Acreo Swedish ICT AB.
    Andrén, B
    Acreo Swedish ICT AB.
    Brunnström, K
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems. Acreo Swedish ICT AB.
    Osterman, J
    LC-Tec Displays AB.
    Perception and annoyance of crosstalk in stereoscopic 3D projector systems2014In: Proc. SPIE 9011, Stereoscopic Displays and Applications XXV / [ed] Woods, A. J., Holliman, N. S., and Favalora, G. E., Bellingham, WA, USA: SPIE - International Society for Optical Engineering, 2014, p. 901125-Conference paper (Refereed)
  • 3072.
    Wang, Ke
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Exploiting Presence2008Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    By exploiting context awareness, traditional applications can be extended to offer better quality or new functions. Utilizing a context-aware infrastructure, a variety of context information is merged and processed to produce information that is useful to applications. Applications exploiting such context can provide more intelligent and creative services to end users.

    This thesis examines two ways to make use of a user’s location along with room occupancy information in context aware applications: a Context Agent and a Call Secretary. In the former case, the application subscribes to room occupancy information via a context server, and provides a Meeting Room Booking System with “real-time” information about the utilization of the rooms which the room booking system is to manage. The Call Secretary acquires both location and room occupancy information from a server. When the user is in one of the meeting rooms and multiple people are present, then this is interpreted as the user being in a meeting -- therefore it triggers a CPL module in a SIP proxy to redirect the user’s incoming call to their voice mail box. A description of the implementation of these two applications will be presented along with an evaluation of these applications’ performance.

    The evaluation of the Context Agent showed that it was straightforward to integrate information from a presence source and to extend the meeting room booking system to use this information. The Call Secretary needs a more reliable source for the user's location. However, given this location the Call Secretary provides the service which the user expects.

  • 3073.
    Wang, Ke
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101). Acreo AB, Kista, Sweden .
    Li, J.
    Djupsjöbacka, A.
    Chacinski, Marek
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101).
    Westergren, Urban
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101).
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101).
    Jacobsen, Gunnar
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101). Acreo AB, Kista, Sweden .
    Hurm, V.
    Makon, R. E.
    Driad, R.
    Walcher, H.
    Rosenzweig, J.
    Steffan, A. G.
    Mekonnen, G. G.
    Bach, H. -. G.
    100 Gb/s complete ETDM system based on monolithically integrated transmitter and receiver modules2010In: 2010 Conference on Optical Fiber Communication, Collocated National Fiber Optic Engineers Conference, OFC/NFOEC 2010, 2010, p. 5465571-Conference paper (Refereed)
    Abstract [en]

    A complete ETDM system based on monolithically integrated transmitter and receiver modules was demonstrated with BER performance below FEC threshold up to 107 Gb/s. ETDM signal at 112 Gb/s with clear eye opening was also observed.

  • 3074.
    Wang, Kun
    et al.
    Nanjing University of Posts and Telecommunications, Nanjing, China.
    Du, Miao
    Nanjing University of Posts and Telecommunications, Nanjing, China.
    Sun, Yanfei
    Nanjing University of Posts and Telecommunications, Nanjing, China.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Zhang, Yan
    University of Oslo, Oslo, Norway & Simula Research Laboratory, Fornebu, Norway.
    Attack Detection and Distributed Forensics in Machine-to-Machine Networks2016In: IEEE Network, ISSN 0890-8044, E-ISSN 1558-156X, Vol. 30, no 6, p. 49-55Article in journal (Refereed)
    Abstract [en]

    The advanced idea of machine-to-machine technology has attracted a new period of network revolution, evolving into a method to monitor and control global industrial user assets, machines, and the production process. M2M networks are considered to be the intelligent connection and communication between machines. However, the security issues have been further amplified with the development of M2M networks. Consequently, it is essential to pour attention into attack detection and forensics problems in M2M networks. This article puts forward the hybrid attack detection and forensics model in M2M networks. It contains two modules: the attack detection module and the forensics analysis module. In addition, we present a distributed anti-honeypot-based forensics strategy to cope with DDoS attacks in the forensics analysis module. Finally, we also discuss some challenges in M2M network security and forensics.

  • 3075.
    Wang, Kun
    et al.
    Nanjing University of Posts and Telecommunications, Nanjing, China.
    Gu, Liqiu
    Nanjing University of Posts and Telecommunications, Nanjing, China.
    He, Xiaoming
    Nanjing University of Posts and Telecommunications, Nanjing, China.
    Guo, Song
    Hong Kong Polytechnic University, Hong Kong, Hong Kong.
    Sun, Yanfei
    Nanjing University of Posts and Telecommunications, Nanjing, China.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Shen, Jian
    Nanjing University of Information Science and Technology, Nanjing, China.
    Distributed Energy Management for Vehicle-to-Grid Networks2017In: IEEE Network, ISSN 0890-8044, E-ISSN 1558-156X, Vol. 31, no 2, p. 22-28Article in journal (Refereed)
    Abstract [en]

    Making full use of V2G services, EVs with batteries may assist the smart grid in alleviating peaks of energy consumption. Aiming to develop a systematic understanding of the interplay between smart grid and EVs, an architecture for the V2G networks with the EV aggregator is designed to maintain the balance between energy suppliers (the grid side) and consumers (the EV side). We propose a combined control and communication approach considering distributed features and vehicle preferences in order to ensure efficient energy transfer. In our model, the integrated communication and control unit can achieve realtime and intelligent management with the logic controller and collected data. On the consumers' side, we theoretically analyze how to satisfy the charging constraints that we incorporate in the form of willingness to pay, and propose a distributed framework to coordinate the energy delivery behaviors for satisfying service demands. Moreover, illustrative results indicate that the proposed approach can yield higher revenue than the conventional pricing mechanism in V2G networks.

  • 3076.
    Wang, Kun
    et al.
    Nanjing University of Posts and Telecommunications, Nanjing, China.
    Wang, Yunqi
    Nanjing University of Posts and Telecommunications, Nanjing, China.
    Hu, Xiaoxuan
    Nanjing University of Posts and Telecommunications, Nanjing, China.
    Sun, Yanfei
    Nanjing University of Posts and Telecommunications, Nanjing, China.
    Deng, Der-Jiunn
    National Changhua University of Education, Changhua City, Taiwan.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Zhang, Yan
    University of Oslo, Oslo, Norway & Simula Research Laboratory, Fornebu, Norway.
    Wireless Big Data Computing in Smart Grid2017In: IEEE wireless communications, ISSN 1536-1284, E-ISSN 1558-0687, Vol. 24, no 2, p. 58-64Article in journal (Refereed)
    Abstract [en]

    The development of smart grid brings great improvement in the efficiency, reliability, and economics to power grid. However, at the same time, the volume and complexity of data in the grid explode. To address this challenge, big data technology is a strong candidate for the analysis and processing of smart grid data. In this article, we propose a big data computing architecture for smart grid analytics, which involves data resources, transmission, storage, and analysis. In order to enable big data computing in smart grid, a communication architecture is then described consisting of four main domains. Key technologies to enable big-data-aware wireless communication for smart grid are investigated. As a case study of the proposed architecture, we introduce a big-data- enabled storage planning scheme based on wireless big data computing. A hybrid approach is adopted for the optimization including GA for storage planning and a game theoretic inner optimization for daily energy scheduling. Simulation results indicate that the proposed storage planning scheme greatly reduce.

  • 3077.
    Wang, Lei
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. Ecole Polytechnique Fédérale de Lausanne, Switzerland.
    Jonsson, B. Lars G.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Mosig, J. R.
    Wideband omnidirectional planar antenna with vertical polarization2017In: 2017 11th European Conference on Antennas and Propagation, EUCAP 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, p. 3865-3868, article id 7928581Conference paper (Refereed)
    Abstract [en]

    In this paper we propose a circular leaky wave-antenna with omnidirectional radiation in the H-plane. The design utilizes double-layered strips to create an end-fire antenna. A linear tapering of the stripes in the design endows the antenna with a 27% impedance bandwidth of 26.4-34.6 GHz. The antenna is vertically polarized with a cross polarization below -30 dB. The antenna has low gain variation in H-plane and it is compact as a planar structure. Furthermore, it can be easily fabricated and integrated by standard PCB processing techniques, which is very promising for applications such as base stations for wireless communication, spectrum monitoring and jamming systems.

  • 3078.
    Wang, Lihui
    National Research Council of Canada.
    A Web-based Approach for Real-time Robot Operations2008In: International Journal of Internet Manufacturing and Services, ISSN 1751-6048, Vol. 1, no 2, p. 90-103Article in journal (Refereed)
    Abstract [en]

    Owing to the business decentralisation and outsourcing, manufacturing is moving toward the direction in distributed environment. A new enabling technology is required, especially in remote monitoring and control of daily manufacturing operations. As web is rooted into business, a web-based solution for real-time monitoring and control is preferable due to its popularity, low cost, and availability. However, unpredictable network traffic posts a major challenge for web-based real-time application development. This paper proposes to use computer graphics augmented with real sensor data for reducing data transmission over the network. Particularly, a web-based technology for remote robot operations is presented.

  • 3079.
    Wang, Lihui
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Fratini, L.
    Shih, A. J.
    Preface2017In: Procedia Manufacturing, ISSN 2351-9789, Vol. 10, p. vii-viiiArticle in journal (Refereed)
  • 3080.
    Wang, Liping
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Fodor, Viktoria
    KTH, School of Electrical Engineering (EES), Communication Networks. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Cooperative geographic routing in wireless mesh networks2010Conference paper (Refereed)
    Abstract [en]

    We propose cooperative geographic routing (cGeo-routing) for wireless mesh networks by combining cooperative transmission with traditional geographic routing. We model and evaluate two cGeo-routing schemes including Cooperative-Random Progress Forwarding (C-RPF) and Cooperative-Nearest with Forward Progress (C-NFP). We show that cGeo-routing significantly increases the average transport capacity for a single hop in well connected mesh networks, and the gain increases with the transmitted signal-to noise ratio (SNR). Moreover, there exists an optimal topology knowledge range in C-RPF, whereas an optimal node density in C-NFP. Our results also suggest that hop-by-hop cooperation can increase transport capacity in high-connectivity and high-SNR regimes, however, it does not change the transport capacity scaling law of the mesh network.

  • 3081.
    Wang, Meiqian
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Furdek, Marija
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Wavelength overprovisioning strategies for enhanced optical path restoration2016In: International Conference on Transparent Optical Networks, IEEE Computer Society, 2016Conference paper (Refereed)
    Abstract [en]

    This paper proposes two wavelength overprovisioning strategies that can be used to improve the performance of path restoration in optical core networks under dynamic traffic conditions while considering single fiber link failure scenarios. The study presented in the paper shows that with the two proposed schemes it is possible to achieve nearly the same level of average connection availability and restorability typical of dedicated path protection schemes (i.e., 100%) with, on the other hand, better blocking probability performance.

  • 3082.
    Wang, Qiwen
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Jaggi, Sidharth
    Chinese Univ Hong Kong, Dept Informat Engn, SE-10044 Stockholm, Sweden..
    End-to-End Error-Correcting Codes on Networks With Worst-Case Bit Errors2018In: IEEE Transactions on Information Theory, ISSN 0018-9448, E-ISSN 1557-9654, Vol. 64, no 6, p. 4467-4479Article in journal (Refereed)
    Abstract [en]

    In highly dynamic wireless networks, communications face several challenges. In the first place, noise levels between nodes might be difficult to predict a priori. Besides, a Byzantine attacker hidden in the network, with knowledge of the network topology and observation of all transmissions, can choose arbitrary locations to inject corrupted packets. Considering that transmissions are usually in bits and hardware in wireless networks usually use modulation schemes with the size of modulation alphabet being powers of two, e.g. BPSK, QPSK, 16-QAM, 64-QAM, and so on, to address the above problem, we study coding for networks experiencing worst case bit errors, and with network codes over binary extension fields. We demonstrate that in this setup prior network error-correcting schemes can be arbitrarily far from achieving the optimal network throughput. A new transform metric for errors under the considered model is proposed. Using this metric, we replicate many of the classical results from coding theory. Specifically, new Hamming-type, Plotkin-type, and Elias-Bassalygo-type upper bounds on the network capacity are derived. A commensurate lower bound is shown based on Gilbert-Varshamov (GV)-type codes for error-correction. The GV codes used to attain the lower bound can be non-coherent, that is, they require neither prior knowledge of the network topology nor network coding kernels. We also propose a computationally efficient concatenation scheme. The rate achieved by our concatenated codes is characterized by a Zyablov-type lower bound. We provide a generalized minimum-distance decoding algorithm which decodes up to half the minimum distance of the concatenated codes. The end-to-end nature of our design enables our codes to be overlaid on the classical distributed random linear network codes. The other advantage of the end-to-end strategy over the link-by-link error-correction is that it reduces the computational cost at the internal nodes for performing error-correction.

  • 3083.
    Wang, Qiwen
    et al.
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Symmetric private information retrieval for MDS coded distributed storage2017In: 2017 IEEE International Conference on Communications, ICC 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, article id 7997029Conference paper (Refereed)
    Abstract [en]

    A user wants to retrieve a file from a database without revealing the identity of the file retrieved at the database, which is known as the problem of private information retrieval (PIR). If it is further required that the user obtains no information about the database other than the desired file, the concept of symmetric private information retrieval (SPIR) is introduced to guarantee privacy for both parties. In this paper, the problem of SPIR is studied for a database stored among N nodes in a distributed way, by using an (N, M)-MDS storage code. The information-theoretic capacity of SPIR, defined as the maximum number of information bits of the desired file retrieved per downloaded bit, for the coded database is derived. It is shown that the SPIR capacity for coded database is 1-M/N, when the amount of the shared common randomness of distributed nodes (unavailable at the user) is at least M/N-M times the file size. Otherwise, the SPIR capacity for the coded database equals zero.

  • 3084.
    Wang, Shuai
    Linköping University, Department of Electrical Engineering, Communication Systems.
    Embedding data in an audio signal, using acoustic OFDM2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The OFDM technology has been extensively used in many radio communicationtechnologies. For example, OFDM is the core technology applied in WiFi, WiMAXand LTE. Its main advantages include high bandwidth utilization, strong noise im-munity and the capability to resist frequency selective fading. However, OFDMtechnology is not only applied in the field of radio communication, but has alsobeen developed greatly in acoustic communication, namely the so called acousticOFDM. Thanks to the acoustic OFDM technology, the information can be em-bedded in audio and then transmitted so that the receiver can obtain the requiredinformation through certain demodulation mechanisms without severely affectingthe audio quality.This thesis mainly discusses how to embed and transmit information in audioby making use of acoustic OFDM. Based on the theoretical systematic structure, italso designs a simulation system and a measurement system respectively. In thesetwo systems, channel coding, manners of modulation and demodulation, timingsynchronization and parameters of the functional components are configured in themost reasonable way in order to achieve relatively strong stability and robustnessof the system. Moreover, power control and the compatibility between audio andOFDM signals are also explained and analyzed in this thesis.Based on the experimental results, the author analyzes the performance of thesystem and the factors that affect the performance of the system, such as the typeof audio, distance between transmitter and receiver, audio output level and so on.According to this analysis, it is proved that the simulation system can work steadilyin any audio of wav format and transmit information correctly. However, dueto the hardware limitations of the receiver and sender devices, the measurementsystem is unstable to a certain degree. Finally, this thesis draws conclusions of theresearch results and points out unsolved problems in the experiments. Eventually,some expectations for this research orientation are stated and relevant suggestionsare proposed.

  • 3085.
    Wang, Simiao
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Research on new approach for NAT traversal: ID-Traversal2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 3086.
    Wang, Wendong
    et al.
    Beijing Univ Posts & Telecommun, State Key Lab Networking & Switching Technol, XiTuCheng Rd 10, Beijing 100876, Peoples R China.
    Xi, Teng
    Beijing Univ Posts & Telecommun, State Key Lab Networking & Switching Technol, XiTuCheng Rd 10, Beijing 100876, Peoples R China.
    Ngai, Edith C.-H.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Song, Zheng
    Virginia Tech, Dept Comp Sci, Blacksburg, VA 24060 USA.
    Energy-efficient collaborative outdoor localization for participatory sensing2016In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 16, no 6, article id 762Article in journal (Refereed)
    Abstract [en]

    Location information is a key element of participatory sensing. Many mobile and sensing applications require location information to provide better recommendations, object search and trip planning. However, continuous GPS positioning consumes much energy, which may drain the battery of mobile devices quickly. Although WiFi and cell tower positioning are alternatives, they provide lower accuracy compared to GPS. This paper solves the above problem by proposing a novel localization scheme through the collaboration of multiple mobile devices to reduce energy consumption and provide accurate positioning. Under our scheme, the mobile devices are divided into three groups, namely the broadcaster group, the location information receiver group and the normal participant group. Only the broadcaster group and the normal participant group use their GPS. The location information receiver group, on the other hand, makes use of the locations broadcast by the broadcaster group to estimate their locations. We formulate the broadcaster set selection problem and propose two novel algorithms to minimize the energy consumption in collaborative localization. Simulations with real traces show that our proposed solution can save up to 68% of the energy of all of the participants and provide more accurate locations than WiFi and cellular network positioning.

  • 3087.
    Wang, Willy
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Evaluating the use of PXI modules in tests of a radio base station2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis project was carried out at the electromagnetic compatibility (EMC) department at Ericsson AB. One of the department’s goals is to seek a possible replacement to the box test instruments by utilizing PCI extension for instrumentation (PXI) modules. The main objective of this project is to evaluate how different PXI modules work during testing of a radio base station (RBS), in terms of performance, test time, and cost. A downlink decoder was implemented in LabVIEW with an extension called MathScript and several software test solutions were examined to measure error vector magnitude (EVM), frequency error, and power, and to perform parallel measurements in a multiple radio access technology (multi-RAT) test configuration. Moreover, several uplink tests were performed to decide if PXI modules are a suitable substitute for the previous box based test instruments. The findings from this study show that PXI modules can replace the previous box based test instruments. However it was concluded that not all areas can be covered and not all discrete test instrument can (yet) be replaced. Future work should complete the downlink decoder implementation in the field programmable gate array (FPGA) level in order to further improve the performance further. Future work should also examine if it is possible to replace all of the discrete test instruments with PXI modules.

  • 3088. Wang, X.
    et al.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Wang, L.
    Tornatore, M.
    Chung, H. S.
    Lee, H. H.
    Park, S. M.
    Mukherjee, B.
    Virtualized Cloud Radio Access Network for 5G Transport2017In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 55, no 9, p. 202-209, article id 8030505Article in journal (Refereed)
    Abstract [en]

    Current radio access networks (RANs) need to evolve to handle diverse service requirements coming from the growing number of connected devices and increasing data rates for the upcoming 5G era. Incremental improvements on traditional distributed RANs cannot satisfy these requirements, so the novel and disruptive concept of a cloud RAN (CRAN) has been proposed to decouple digital units (DUs) and radio units (RUs) of base stations (BSs), and centralize DUs into a central office, where virtualization and cloud computing technologies are leveraged to move DUs into the cloud. However, separating RUs and DUs requires low-latency and high-bandwidth connectivity links, called "fronthaul," as opposed to traditional backhaul links. Hence, design of the 5G transport network, that is, the part of the network that carries mobile data traffic between BSs and the core network and data centers, is key to meet the new 5G mobile service requirements and effectively transport the fronthaul traffic. Today, consensus is yet to be achieved on how the fronthaul traffic will be transported between RUs and DUs, and how virtualization of network resources will occur from a radio network segment to the centralized baseband processing units. In this article, we present a new 5G architecture, called virtualized cloud radio access network (V-CRAN), moving toward a cell-less 5G network architecture. We leverage the concept of a virtualized BS (V-BS) that can be optimally formed by exploiting several enabling technologies such as software defined radio (SDR) and coordinated multipoint (CoMP) transmission/reception. A V-BS can be formed on a per-cell basis or per-user basis by allocating virtualized resources on demand. For the fronthaul solution, our approach exploits the passive optical network (PON), where a wavelength can be dynamically assigned and shared to form a virtualized passive optical network (VPON). Several use cases of the V-CRAN are presented to show how network architecture evolution can enhance system throughput, energy efficiency, and mobility management.

  • 3089. Wang, X.
    et al.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Wang, L.
    Tornatore, M.
    Zhao, Y.
    Chung, H. S.
    Lee, H. H.
    Park, S.
    Mukherjee, B.
    Joint allocation of radio and optical resources in virtualized cloud RAN with CoMP2017In: 2016 IEEE Global Communications Conference, GLOBECOM 2016 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2017, article id 7841923Conference paper (Refereed)
    Abstract [en]

    5G Radio Access Networks (RANs) are supposed to increase their capacity by 1000x to handle growing number of connected devices and increasing data rates. The concept of cloud-RAN (CRAN) has been recently proposed to decouple digital units (DUs) and radio units (RUs) of base stations (BSs), and centralize DUs into central offices. CRAN can ease the implementation of advanced radio coordination techniques, e.g., Coordinated Multi-Point (CoMP) Transmission/Reception, to enhance its system throughput. However, separating DUs and RUs, and implementing CoMP in CRAN require low-latency and high-bandwidth connectivity links, called "fronthaul". Today, consensus has not yet been achieved on how BSs, fronthaul, and central offices will be orchestrated to enhance the system throughput. In this study, we present a CRAN over Passive Optical Network (PON) architecture called virtualized-CRAN (V-CRAN). V-CRAN leverages the concept of virtualized PON (VPON) that can dynamically associate any RU to any DU so that several RUs can be coordinated by the same DU, and the concept of virtualized BS (V-BS) that can jointly transmit common signals from multiple RUs to a user. We propose a novel mathematical model based on constraint programming for joint allocation of radio, optical network, and baseband processing resources to enhance RAN throughput, and we solve it by optimally forming VPONs and V-BSs. Comprehensive simulations show that V-CRAN can enhance the system throughput and the efficiency of resource utilization.

  • 3090. Wang, X.
    et al.
    Wang, L.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Tornatore, M.
    Figueiredo, G. B.
    Chung, H. S.
    Lee, H. H.
    Park, S.
    Mukherjee, B.
    Handover reduction in virtualized cloud radio access networks using TWDM-PON fronthaul2016In: Journal of Optical Communications and Networking, ISSN 1943-0620, E-ISSN 1943-0639, Vol. 8, no 12, p. B124-B134Article in journal (Refereed)
    Abstract [en]

    To meet challenging 5G capacity requirements, operators are densifying their cellular networks by deploying additional small cells to cover hot spots, and such an increase in the number and density of cells may result in excessive numbers of handovers. In this study, we propose a handover reduction mechanism implemented in a cloud radio access network (CRAN) by exploiting the high capacity of an optical access network serving as a "fronthaul." CRAN has been proposed as a 5G radio access network architecture, where the digital unit (DU) of a conventional base station (BS) is separated from the radio unit (RU) and moved to the "cloud" (DU-cloud) for better mobility management and cost saving. Separating RUs and DUs requires a low-latency and high-bandwidth 5G transport network to handle "fronthaul" traffic, for which optical access is an excellent choice. Here, we present a new 5G architecture, called virtualized-CRAN (V-CRAN), moving toward a cell-less 5G mobile network architecture. We leverage the concept of a "virtualized-BS" (V-BS) that can be formed by exploiting several enabling technologies such as software-defined radio and coordinated multipoint transmission/reception. A V-BS can be formed on a per-user basis by allocating virtualized resources on demand so that common signals can be jointly transmitted from multiple RUs to the user without triggering handover. We first model the handover reduction optimization problem for a scenario where future mobility information is known, and then propose a suite of algorithms for a scenario where future information is unknown. Simulation results show that V-CRAN can enhance the throughput of users at the cell-edge, as well as significantly reduce the number of handovers, handover delay, and failure rate.

  • 3091.
    Wang, Xiaoxin
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    3G HSDPA Performance In Mobile Internet Connections2004Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A key objective for 3G wireless networks, such as the Universal Mobile Telecommunication System (UMTS), is the explicit support for data communications for mobile users. Today, the dominant transport protocol in the Internet is the Transport Control Protocol (TCP). Since TCP was not tailored for wireless networks, there are some performance issues occurring when TCP traffic is transferred over a UMTS radio link.

    In this paper, the characteristics of TCP and UMTS are specified and the problems of TCP over UMTS dedicated channels (DCHs) are analyzed. The problem is high delays implying low utilization of allocated resources for small file transfers or due to packet losses. High Speed Downlink Packet Access (HSDPA)’s potential to solve the problem is studied. Since in HSDPA, High-Speed Downlink shared channel (HS-DSCH) is introduced as an alternative of DCH on downlink packet access, a model of HS-DSCH is built and simulations are performed in order to compare its TCP performance with DCH. The focus is on studying retransmission delay and Block Error Rate (BLER) targets. Some scheduling methods are also compared. The results indicate that HS-DSCH gives better TCP performance than a DCH, and that advanced scheduling methods gives similar result as round robin if there are packet losses. Moreover, a somewhat surprising result is found regarding fast retransmission and channel utilization for increasing BLER targets.

  • 3092.
    Wang, Y.
    et al.
    Xi'an Jiaotong University.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Wang, X.
    Xi'an Jiaotong University.
    A Non-cooperative Scheme for SFR-Based Power Control in LTE Networks2014Conference paper (Refereed)
    Abstract [en]

    We propose a non-cooperative power allocation scheme for cellular systems using soft frequency reuse and in the power control, each user selfishly maximizes its utility.To find the tradeoff between QoS satisfaction and energy consumption, we design a utility function that considers both QoS requirements and the cost. We then show there exists a Nash equilibrium and provide conditions to assure its uniqueness. This scheme has limited signaling overhead and only pricing information needs to be exchanged among cells. Simulation results show that this scheme improves throughput and coverage performance compared with conventional SFR schemes.

  • 3093. Wang, Y.
    et al.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Wang, X.
    Joint Interference Mitigation and Power Allocation for Multi-Cell LTE Networks: A Non-Cooperative Game Approach2014In: 2014 IEEE 80th Vehicular Technology Conference (VTC Fall), IEEE , 2014, p. 6966031-Conference paper (Refereed)
    Abstract [en]

    We propose a non-cooperative game-theoretic power allocation (NGPA) scheme for interference mitigation in long term evolution (LTE) uplink in this paper. We first set up the interference model employing conventional soft frequency reuse (SFR) scheme for inter-cell interference coordination (ICIC) in a nineteen-cell LTE network. Since each user may selfishly maximize its own performance in power allocation, we design a utility function that considers both quality of service (QoS) satisfaction and energy consumption. We then investigate the existence of Nash equilibrium and derive a sufficient condition to assure its uniqueness. Simulation results show that the proposed scheme improves throughput and coverage performances compared with conventional SFR schemes. Moreover, this scheme only requires limited signaling overhead among cells, which can be readily implemented in a distributed manner for practical systems.

  • 3094. Wang, Y.
    et al.
    Wei, Xiaoyu
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Timus, Bogdan
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sankar, R.
    Morgera, S.
    Feasibility study of pico cellular-relaying system in urban outdoor environment2011In: 2011 IEEE 12th Annual Wireless and Microwave Technology Conference, WAMICON, 2011Conference paper (Refereed)
    Abstract [en]

    Heterogeneous networks, in particular cellular-relaying networks, have the potential to provide high data-rate services at low infrastructure costs. Macro and micro base stations have traditionally been used to provide coverage and capacity, respectively. In this paper, we analyze a new approach in which coverage is provided by means of inband relays. We show that compared with a traditional network based on macro base stations, a good outdoor coverage for a target data rate could be provided in a more cost efficient way by deploying a network based on pico base stations and relays. However, this is valid only for low data-rate because part of the spectrum is allocated to the backhaul and therefore the capacity of cellular-relaying networks is typically limited. Moreover, this break-even point depends on how the networks are deployed.

  • 3095.
    Wang, Yuanshuang
    et al.
    Xi'an Jiaotong University.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Wang, Xia
    Xi'an Jiaotong University.
    An Energy-Efficient Non-Cooperative Game Approach for Channel-Aware Distributed Medium Access Control2014In: 2014 IEEE 80th Vehicular Technology Conference (VTC Fall), IEEE , 2014, p. 1-6Conference paper (Refereed)
    Abstract [en]

    In this paper, an energy-efficient non-cooperative game approach is proposed for channel-aware distributed medium access control (EN-CDMAC) in slotted-Aloha systems, where users act selfishly to improve their own utilities. To resolve the network contention in a distributed manner, the capture model is employed and a pricing-based non-cooperative game scheme is designed to enable selfish users effectively achieve multi-user diversity by adjusting their equilibrium thresholds while guaranteeing fairness by the pricing mechanism. Then the existence of Nash equilibrium is proved, and the necessary and sufficient condition is derived to ensure its uniqueness. Furthermore, the equilibrium stability is investigated with stochastic process theory. Simulation results show that the proposed approach significantly improves the network throughput and delay performance without sacrificing energy efficiency compared to the conventional slotted-Aloha scheme. In particular, the proposed approach is more applicable for high-load systems.

  • 3096. Wang, Yujue
    et al.
    Hauser, Carl
    Wu, Yiming
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Quantifying Uncertainties of Security and QoS for Design of Power Grid Communications Systems2016In: 2016 49th Hawaii International Conference on System Sciences (HICSS), IEEE Computer Society, 2016, p. 2566-2575Conference paper (Refereed)
    Abstract [en]

    Reliable and secure communication, and high quality of service (QoS) (low latency, high availability, etc.) of data are critical to the successful operation of power systems. However, uncertainties, both aleatory and epistemic, are inherent to the system, which makes it difficult to secure the communication while fulfilling the QoS requirements. Nowadays, the administrators of the power grid's communication system have much flexibility in choosing a specific security scheme but the uncertainties make answering the question "what is the best scheme" or even "what is an adequate scheme" very difficult. Appropriately quantifying uncertainty and its effects on security is a key to choosing a sufficiently secure communication system for power grid while meeting QoS requirements. In this paper, we model aleatory and epistemic uncertainties using probability distributions and subjective logic respectively. Comprehensive quantification of the uncertainties can greatly sharpen administrators' understanding of the trade-offs between security and QoS and help them to select the most fitting security scheme to meet the QoS requirements. A case study demonstrates how our method works for two different application scenarios.

  • 3097.
    Wang, Yun
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Jiang, Wenxuan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Statistical Processing of IEEE 802.15.4 Data Collected in Industrial Environment2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Wireless sensor network, which is constitute of autonomous sensors, is used for monitoring physical or environmental conditions like temperature, sound, pressure, and so on. The dispersed sensors or nodes will respectively pass their data through the network to the main location. Currently, several standards are ratified or in developing for wireless sensor network, like Wireless Hart, ISA, 100.11a, WIA-PAA, IEEE 802.15.4, etc. Among the standards, Zigbee is often used in industrial applications that require short-range and low-rate wireless transfer. In the research, all the data is collected under industrial environment using IEEE 802.15.4 compliant physical layer, some packets are interfered only by multi-path fading while others are also interfered by Wi-Fi interference. The goal of the thesis is to find out the dependence between the received power (RSS), correlation value (CORR) and bit error rate (BER) of the received message, and their distribution in situations both when the packet is lost or not. Besides, the performance of bit error rate such as the distribution and the features of burst error length under Wi-Fi interference or not will also be tested. All of them are based on a precise statistical processing. 

  • 3098. Wang, Z.
    et al.
    Chen, Xiaowen
    KTH, School of Information and Communication Technology (ICT), Electronics. National University of Defense Technology, China.
    Li, C.
    Guo, Y.
    Fairness-oriented and location-aware NUCA for many-core SoC2017In: 2017 11th IEEE/ACM International Symposium on Networks-on-Chip, NOCS 2017, Association for Computing Machinery (ACM), 2017, article id 13Conference paper (Refereed)
    Abstract [en]

    Non-uniform cache architecture (NUCA) is often employed to organize the last level cache (LLC) by Networks-on-Chip (NoC). However, along with the scaling up for network size of Systems-on-Chip (SoC), two trends gradually begin to emerge. First, the network latency is becoming the major source of the cache access latency. Second, the communication distance and latency gap between different cores is increasing. Such gap can seriously cause the network latency imbalance problem, aggravate the degree of non-uniform for cache access latencies, and then worsen the system performance. In this paper, we propose a novel NUCA-based scheme, named fairness-oriented and location-aware NUCA (FL-NUCA), to alleviate the network latency imbalance problem and achieve more uniform cache access. We strive to equalize network latencies which are measured by three metrics: average latency (AL), latency standard deviation (LSD), and maximum latency (ML). In FL-NUCA, the memory-to-LLC mapping and links are both non-uniform distributed to better fit the network topology and traffics, thereby equalizing network latencies from two aspects, i.e., non-contention latencies and contention latencies, respectively. The experimental results show that FL-NUCA can effectively improve the fairness of network latencies. Compared with the traditional static NUCA (SNUCA), in simulation with synthetic traffics, the average improvements for AL, LSD, and ML are 20.9%, 36.3%, and 35.0%, respectively. In simulation with PARSEC benchmarks, the average improvements for AL, LSD, and ML are 6.3%, 3.6%, and 11.2%, respectively.

  • 3099.
    Wang, Zhao
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Schaefer, Rafael F.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Poor, H. Vincent
    Xiao, Ming
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Strong Secrecy for Interference Channels from Channel Resolvability2015In: 2015 49th Asilomar Conference on Signals, Systems and Computers, IEEE Computer Society, 2015, p. 559-563, article id 7421191Conference paper (Refereed)
    Abstract [en]

    The achievable rate region is studied for interference channels with confidential messages under strong secrecy constraints. The problem is investigated based on the framework of the channel resolvability theory. The information-spectrum method introduced by Han and Verdu is first generalized to an arbitrary interference channel to obtain a direct channel resolvability result. The derived resolvability results are then shown to be the achievable strong secrecy rates for the stationary and memoryless interference channel. Our results provide further evidence that channel resolvability can be a powerful and general framework for strong secrecy analysis in multiuser networks.

  • 3100.
    Wang, Zhao
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Xiao, Ming
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Secrecy degrees of freedom of the 2 interference channel with delayed CSIT2014In: IEEE Wireless Communications Letters, ISSN 2162-2337, E-ISSN 2162-2345, Vol. 3, no 4, p. 341-344, article id 6784143Article in journal (Refereed)
    Abstract [en]

    We consider the two-hop interference channel with confidential messages (ICC), where each transmitter sends one confidential message to its intended destination through two trusted relays. We study the secrecy degrees of freedom (SDoF) of the considered 2 ?2 ?2 ICC with delayed channel state information at transmitters (CSIT). We settle the optimal SDoF of the considered network to be (1/2, 1/2). Thus, the considered network has a strictly larger sum SDoF than a two-user one-hop ICC with even full CSIT. Moreover, we study the SDoF of the network with limited Shannon feedback, that only one relay can obtain the delayed CSIT and output feedback from the destinations. The optimal SDoF is also shown to be (1/2, 1/2), revealing that only limited feedback can also bring SDoF gain. Our proposed achievable schemes in both cases are integrated forms of the retrospective interference alignment and artificial noise transmission.

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