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  • 51.
    Al-Zubaidy, Hussein Mohammed
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Dán, György
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Fodor, Viktoria
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Performance of in-network processing for visual analysis in wireless sensor networks2015In: Proceedings of 2015 14th IFIP Networking Conference, IFIP Networking 2015, IEEE conference proceedings, 2015Conference paper (Refereed)
    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%.

  • 52. Ambat, S. K.
    et al.
    Chatterjee, Saikat
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Hari, K. V. S.
    Adaptive selection of search space in look ahead orthogonal matching pursuit2012In: 2012 National Conference on Communications, NCC 2012, 2012, 6176852- p.Conference paper (Refereed)
    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.

  • 53.
    Amin, Yasar
    et al.
    University of Engineering and Technology, Taxila, Punjab, Pakistan.
    Shao, Botao
    KTH, School of Information and Communication Technology (ICT), Electronic Systems. KTH, School of Information and Communication Technology (ICT), Centres, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Chen, Qiang
    KTH, School of Information and Communication Technology (ICT), Electronic Systems. KTH, School of Information and Communication Technology (ICT), Centres, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Zheng, Li-Rong
    KTH, School of Information and Communication Technology (ICT), Electronic Systems. KTH, School of Information and Communication Technology (ICT), Centres, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Tenhunen, Hannu
    KTH, School of Information and Communication Technology (ICT), Electronic Systems. KTH, School of Information and Communication Technology (ICT), Centres, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Electromagnetic Analysis of Radio Frequency Identification Antennas for Green Electronics2013In: Electromagnetics, ISSN 0272-6343, E-ISSN 1532-527X, Vol. 33, no 4, 319-331 p.Article in journal (Refereed)
    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.

  • 54.
    Amso, Julian
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Faienza, Achille
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    IPsec Intrusion Detection Analysis: Using data from an Ericsson Ethernet Interface Board2008Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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.

  • 55. Anand, K.
    et al.
    Ganapathy, S.
    Kulothungan, K.
    Yogesh, P.
    Kannan, Anand
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    A Rule Based Approach for Attribute Selection and Intrusion Detection in Wireless Sensor Networks2012In: International Conference On Modelling Optimization And Computing, Elsevier, 2012, 1658-1664 p.Conference paper (Refereed)
    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.

  • 56. Andersen, O.
    et al.
    Wisell, David
    KTH, School of Electrical Engineering (EES), Signal Processing. University of Gävle, Sweden.
    Keskitalo, N.
    Stenvard, P.
    Cost effective high performance modular instrumentation, signal generation and signal analysis for future mobile communication systems2007In: 2007 IEEE Autotestcon, IEEE , 2007, 660-668 p.Conference paper (Refereed)
    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.

  • 57.
    Andersson, Dan
    KTH, School of Technology and Health (STH), Data- och elektroteknik.
    Implementation av prototyp för inomhuspositionering2013Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Development of technology constantly creates new opportunities but it can also mean major chang-es for companies and organizations. Today phones, tablets, laptops, mobile communications and cloud technology make it possible to be no longer bound by the time, location or device in order to work. The change means that a new office type that is more flexible and space efficient due to no fixed workplaces, is becoming more common. A problem with this type of offices that are known as flex-offices is that it is not obvious where or when a colleague is in the office, especially if it is large office with multiple floors.

    The aim of this work is to develop and implement a Location-Based Service for the company Connecta AB. The service will enable users to use their mobile phone to share their current workplace location in an office environment.

    The result of this work is a Location-Based Service that enables a user to use an Android phone with support for Near Field Communcication to share their current workplace position. The cloud-based server solution, Windows Azure is used to store indexed workplace positions.

  • 58.
    Andersson, Mattias
    et al.
    KTH, School of Information and Communication Technology (ICT).
    Dávila, Javier
    KTH, School of Information and Communication Technology (ICT).
    Energieffektiva byggmaterials påverkan på radiosignaler: Dämpning av radiosignaler i nya fastigheter2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The goal of this thesis is to examine the attenuation of new building materials on radio signals and the environmental effects that any signal improving solution might have.

    Environmental awareness and sustainable solutions are key issues when planning new buildings. Energy conservation and planning for the future puts pressure on companies to rethink the way they plan and construct new buildings.

    New materials and new techniques are required to reduce the amount of energy it takes to heat our buildings. One unfortunate drawback is the attenuation these new materials have on radio signals. This creates problems for the tenants as they are no longer able to use their mobile telephones indoors.

    To get around that problem a windows or door to the balcony is opened to get an acceptable reception. The energy losses that occur as a result are important to consider. A decrease in these energy losses might serve as an incentive for real estate owners to invest in signal improving solutions for their buildings.

    To get a better understanding of the problem, tests were performed in buildings that incorporate these new materials and techniques. The results of these tests were then used in mathematical models to analyze and to get a better understand the size of the problem. The results show a significant difference when compared to values used in previous calculations where 15dB was seen as a reasonable. This report suggest that the old value is changed to 23dB as seen in the analysis of the data collected. When this new value is used in the surface coverage models, the decrease in cell coverage from the base station becomes evident.

  • 59.
    Andersson, Mattias
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Wyrembelski, R. F.
    Oechtering, Tobias J.
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Polar codes for bidirectional broadcast channels with common and confidential messages2012In: International Symposium on Wireless Communication Systems (ISWCS), 2012, IEEE conference proceedings, 2012, 1014-1018 p.Conference paper (Refereed)
    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.

  • 60.
    Andersson, Per
    et al.
    Handelshögskolan, Stockholm School of Economics.
    Markendahl, Jan
    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.
    Capabilities for Network Operations and Support of Customers’ Working Processes2007Conference paper (Refereed)
    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. 

  • 61.
    Andreasson, Carin
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, 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 credits / 30 HE creditsStudent thesis
    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.

  • 62.
    André, Johan
    KTH, Superseded Departments, Teleinformatics.
    Automated test procedure for GSM Over-The-Air SIM file management1999Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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%.

  • 63.
    Angeles Piña, Carlos
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Distribution of Context Information using the Session Initiation Protocol (SIP)2008Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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.

  • 64. Ansari, A.
    et al.
    Jaumard, B.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Energy optimization of a cellular network with minimum bit-rate guarantee2017In: 2017 15th International Symposium on Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks, WiOpt 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, 7959933Conference paper (Refereed)
    Abstract [en]

    Energy optimization in cellular networks has been studied using different perspectives in the literature: sleep patterns, network interference, association of users and base stations, resource allocation of resources (bandwidth and power), etc. All these means have been discussed individually in previous works. However, none of the existing works has succeeded in proposing an exact mathematical model that takes into account several of these parameters simultaneously. In this article, we propose a first exact modelling of several network parameters and their interaction in order to minimize the energy consumption in a LTE cellular network. The optimization model guarantees to satisfy all the users with a minimum quality of service (data rate). Its exact solution allows energy savings of up to 50% in a moderately loaded network, which leads to energy savings up to twice that of the heuristic proposed by Piunti et al., (2015). Various numerical results are presented on hexagonal and randomly generated cellular networks.

  • 65.
    Apanasevic, Tatjana
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Barriers to further commercialization of NFC pilots in Western Europe2013In: The Second International Cashless Society Roundtable (ICSR) / [ed] Fergal Carton and Jonas Hedman, 2013, 39-41 p.Conference paper (Refereed)
    Abstract [en]

    A mobile payment can be performed in various ways. For example, the Near Field Technology (NFC) integrated with mobile devices provides an opportunity of a contactless mobile payment. However, it is not only payment. The NFC can further expand functionality of mobile phones and enrich consumer experience. Indeed, added value services created by the NFC include mobile ticketing, loyalty applications, smart advertisement, informational service, physical and logical access, and other functionalities.

    However, despite NFC potential to create added value we cannot witness its wide penetration and global spread unless some successful solutions are implemented on a national level. The research aims to define the barriers preventing NFC pilots from entering commercialization stage in Western Europe. Commercialization of NFC mobile solutions needs to overcome a range of barriers and obstacles predefined by macro- and micro-environmental conditions, and individual factors related to consumers, which are analized in this research.

  • 66.
    Apanasevic, Tatjana
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Challenges Related to the Introduction of Innovative Services in the Market: Mobile Payment Services in the Swedish Retail Industry2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Mobile payment services are expected to be the next step of the electronic payment evolution. However, the level of penetration in European countries is lower than expected. The focus of most academic research has been in two main areas: (i) mobile payment adoption by consumers and (ii) technical aspects of the service. Consequently, a number of themes remain under-researched. In order to expand knowledge on reasons that affect the wider penetration of mobile payments, challenges related to the introduction of mobile payment services in the market have been explored in this thesis.

    More specifically, this research has addressed two problem areas: (i) why mobile payments have not been widely adopted by merchants; and (ii) what effects that the introduction of mobile payments has had on the business networks of the involved actors. As an example, we use the mobile payment services applied in the Swedish retail industry. The study is focused on the main groups of stakeholders – the mobile payment providers, the retailers, and the consumers.

    First, this study has helped to identify what different stakeholders expect of mobile payments and how these services correspond to their needs. In order to analyse the expectations of stakeholders, we have developed an analysis framework based on the theory of diffusion of innovations, the Technology Acceptance Model (TAM), and the theory of network externalities. The analysis highlights the expectations of stakeholders and helps to understand what kind of mobile payment service merchants expect and are willing to adopt. One key finding is that existing mobile payment services for retailing could be further improved in order to ensure an enhanced purchasing process for consumers.

    Second, the research has explored the impact of mobile payment services on the business networks. In order to analyse the relationships and cooperation between business actors, and changes in business strategy and network structure, we used the approach proposed by the Industrial Marketing and Purchasing (IMP) Group. The performed analysis illustrates the following changes in the structure of business networks for the traditional payment solutions (bank cards): (i) emergence of new business actors (i.e. independent mobile payment providers); (ii) new roles and activities of business actors; and (iii) exclusion of traditional business actors (i.e. banks) from the mobile payment systems.

    All these changes lead to increased complexity of relationships and increased level of interdependence between business actors within the networks. The following changes in the strategies of involved actors have been identified: (i) mobile payment providers seek to achieve a control over the business network; (ii) the retailers affect strategies of the mobile payment providers; (iii) the marketing strategies of business actors include cross-marketing in different sectors. All these changes result in additional value and enhanced quality of service for consumers.

    In order to analyse a complex and multidisciplinary area such as mobile payments, it is beneficial to use more than one analysis approach. A combination of different complementing methods helps to explore different aspects of the phenomenon and provides a more comprehensive overview of several research aspects.

    This work contributes to the academic research of mobile payment service adoption by merchants through proposing a theoretical analysis framework. More specifically, the research addresses a new area – expectations of retailers when new solutions are introduced. The framework consists of the following criteria and aspects: technological feasibility, economic benefits, lower service costs, added value of services, network externalities and the problem of critical mass, and finally, ease of use. This framework helps to identify what merchants can expect of mobile payment services.

    Another area of contribution is the analysis of the effect that mobile payments make on the actors and business networks of traditional payment services. The introduction of new services results in emergence of new business actors, a need to establish new relationships, and increased complexity of a business network. Moreover, in order to succeed, cooperation between all network actors is needed. As a result, business actors have to adjust their services and strategies according to needs of others.

  • 67.
    Apanasevic, Tatjana
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Obstacles to investments in mobile payments: The perspective of merchants: Work in progress2013Conference paper (Refereed)
    Abstract [en]

    The main objective of the ongoing research is to investigate obstacles and driving forces affecting merchants’ decision to invest in mobile payment solutions. The core aim of this paper is to present initial results of a desktop analysis revealing the current market situation, identifying main players, and estimating the structure of investment costs. In order to do that available secondary information was analyzed.

    The conducted analysis served to identify market fragmentation existing in the Swedish market due to existence of a number of competing mobile payment solutions. Another finding allows making conclusion, that retailers select to adopt already existing solutions, rather than developing own. Finally, the size of an organization and financial resources are important when making a decision to invest in a new payment solution.

  • 68.
    Apanasevic, Tatjana
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Markendahl, Jan
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth. KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    The mobile payment in retail: Teaching case summary2013In: The 29th Annual IMP Conference (IMP2013) proceedings: Building and Managing Relationships in a Global Network: Challenges and Necessary Capabilities / [ed] Minna Rollins and Brian Rutherford, IMP Group, 2013Conference paper (Refereed)
    Abstract [en]

    The case is written for master level students from business, commerce, and technical areas having some background in strategic marketing and management. The work over case implies a group work and a discussion of a strategy behind taken decision.

    THE OBJECTIVES OF THE CASE

    The main objective of the case is to gain practical skills in and better understanding of decision making in the circumstances of market uncertainty. The decision making process requires analysis of company’s core competences (Collis and Montgomery, 2008), market forces (Porter, 1996; Porter, 2008), and understanding of consumer needs. Students should apply different analysis frameworks in order to develop a strategy improving company’s competitive advantage and leveraging opportunities provided by a new technology, namely a new mobile payment solution. In addition, a consumer-centered thinking should lead to a suggestion of a bundle of attractive added values services build on top of mobile payment solution.

  • 69.
    Apanasevic, Tatjana
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Markendahl, Jan
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth. KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Arvidsson, Niklas
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Entrepreneurship and innovation.
    An exploratory study of consumer attitudes towards mobile ticketing in Sweden2013In: 24th European Regional Conference of the International Telecommunications Society: Technology, Investment and Uncertainty, ITS , 2013Conference paper (Refereed)
    Abstract [en]

    Swedish public transport organizations have set an objective to double usage of the public transport during the next coming five years. This study attempts to investigate if the current ticket solutions support the goal of the public transport companies, and if the available mobile phone solutions can lower barriers for consumers. In order to do that, critical travelling moments for users of different market segments were estimated during a pre-study stage. The following focus group discussions helped to validate problems identified during the pre-study. At the same time, focus groups provided deeper consumer insights on general consumer perception of the transport service, ticketing, mobile payment, quality of service, consumer expectations related to the public transport services, and consumer satisfaction and loyalty.

    The conducted research helped to identify problems existing in public transport ticketing and mobile payment areas, which have the negative impact on the usage of the public transport service and contribute with additional barriers for users. Moreover, this conclusion is supported by multiple examples that clearly illustrate what does not work, and why it does not work. Hence, mentioned solutions do not support the overall objective of the public transport operators. The comprehension of these problems and barriers can contribute to a better understanding of consumer needs and expectations, and help the public transport service providers to improve the service.

  • 70. Apolonia, N.
    et al.
    Freitag, F.
    Navarro, L.
    Girdzijauskas, Sarunas
    KTH, School of Information and Communication Technology (ICT), Software and Computer systems, SCS.
    Vlassov, Vladimir
    KTH, School of Information and Communication Technology (ICT), Software and Computer systems, SCS.
    Gossip-based service monitoring platform for wireless edge cloud computing2017In: Proceedings of the 2017 IEEE 14th International Conference on Networking, Sensing and Control, ICNSC 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, 789-794 p., 8000191Conference paper (Refereed)
    Abstract [en]

    Edge cloud computing proposes to support shared services, by using the infrastructure at the network's edge. An important problem is the monitoring and management of services across the edge environment. Therefore, dissemination and gathering of data is not straightforward, differing from the classic cloud infrastructure. In this paper, we consider the environment of community networks for edge cloud computing, in which the monitoring of cloud services is required. We propose a monitoring platform to collect near real-time data about the services offered in the community network using a gossip-enabled network. We analyze and apply this gossip-enabled network to perform service discovery and information sharing, enabling data dissemination among the community. We implemented our solution as a prototype and used it for collecting service monitoring data from the real operational community network cloud, as a feasible deployment of our solution. By means of emulation and simulation we analyze in different scenarios, the behavior of the gossip overlay solution, and obtain average results regarding information propagation and consistency needs, i.e. in high latency situations, data convergence occurs within minutes.

  • 71.
    Arcos, Alejandro
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    A context-aware application offering map orientation2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis context refers to information about the environment (the user or entity's surroundings) that can influence and determine the behavior of a computing system. Context-awareness means that the computer can adapt to the situation in which it is working. Context is a key issue in mobile computing, especially with handheld devices (such as PDAs and mobile phones), due to the fact that they can be used while on the move; hence the environment around them can change. The environment of a static device may also change and require the device to adapt. Applications and systems that exploit context by both sensing and reacting to their environment are called context-aware applications. Devices that are context-aware are able to perceive stimuli and react accordingly, with minimal interaction with the user.

    Providing context-aware services to users of mobile devices via context-aware applications is becoming an important and significant factor in the market and is a developing industry. In this thesis we analyze and develop an application that exploits context to provide a service that improves the interaction between humans and a computer. The thesis begins with a study of what types of sensors are available to provide information about the device's context. This is followed by the design of an appropriate way of using the selected sensor (ecompass) to provide a means of adapting a service to the user's and device's context. The focus is every day activities of a student at a university - specifically finding the location of a meeting room for a seminar; however, similar scenarios exist for other types of users.

    After determining that it was feasible to add a e-compass as a sensor to an existing personal digital assistant and to provide a map to the mobile user, the focus of the thesis shifted to an examination of the performance of the adaptation of the map as the user moved the device. Initially it required excessive time to render the map on the device, thus as the user moved the device the map was not updated quickly enough for the user to know their correct orientation with respect to the map. Therefore the thesis project examined how this performance could be improved sufficiently that the rendering would keep up with the change in orientation of the device. This investigation lead to a shift from server based rendering of the map as an image, followed by the transfer of the image to the device for display; to a sending a scalable vector graphics version of the map to the device for local rendering. While initially this was expected to be much faster than transferring an image for an actual map of the building where this work was taking place the local rendering was actually slower. This subsequently lead to server based pruning of the irrelevant details from the map, then a transfer of the relevant portion of the map to the device, followed by local rendering.

  • 72.
    Ardelius, John
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture, Software and Computer Systems, SCS.
    Meji­as, B.
    Modeling the performance of ring based DHTs in the presence of network address translators2011In: Lecture Notes in Computer Science, ISSN 0302-9743, E-ISSN 1611-3349, Vol. 6723, 15-28 p.Article in journal (Refereed)
    Abstract [en]

    Dealing with Network Address Translators (NATs) is a central problem in many peer-to-peer applications on the Internet today. However, most analytical models of overlay networks assume the underlying network to be a complete graph, an assumption that might hold in evaluation environments such as PlanetLab but turns out to be simplistic in practice. In this work we introduce an analytical network model where a fraction of the communication links are unavailable due to NATs. We investigate how the topology induced by the model affects the performance of ring based DHTs. We quantify two main performance issues induced by NATs namely large lookup inconsistencies and increased break-up probability, and suggest how theses issues can be addressed. The model is evaluated using discrete based simulation for a wide range of parameters.

  • 73.
    Arefi Anbarani, Hossein
    KTH, Superseded Departments, Teleinformatics.
    ATM PON1998Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This document contains the final report of the thesis project: ATM based passive optical networks (ATM PONs). PONs are being tried as a method of extending optical fibres into the access network. PONs offer the ability of sharing the transmission costs of the access network amongst a large number of customers by allowing fibre and bandwidth sharing via passive optical splitters. ITU-T recommendation G.983 defines a specification for ATM based PONs. An SDL model was used in the project to investigate the possibility of using the Ericsson ATM switch (AXD 301) as the head-end in a G.983 compliant PON (i.e., the OLT). Also some simulations was made, using SDT. The results indicated that the ATM switch could very well serve as an OLT (by addition of a connection board). It was concluded that although the complexity of the system is quite high (caused by the TDMA technique used), it is a feasible solution. A techno-economical analysis made in the initial part of this project indicates that PONs are too expensive for deployment in the near future, compared to enhanced copper networks using xDSL technology. However, new applications could boost demand for high bandwidth sooner than expected. In any case, PONs (except in the FTTH configuration) constitute a natural upgrade for enhanced copper networks.

  • 74.
    Arguello Baltodano, Maria Jimena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Mesh-Relay with MRC in 802.16j Networks2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Multi-hop relay networks are a recent trend in WiMAX 802.16j networks. Many studies on the viability of relay stations have been done. It shows that RS are good cost-effective solution to the increasing demands on wireless broadband services. One problem that faces the 802.16j standard is its topology. It is a tree based multi-hop relay network, which is very vulnerable to single point breakage. This thesis proposes a new robust pairing technique in 802.16j network; combining a mesh topology with maximal ratio combining at the access link. Maximal ratio combining takes advantage of the broadcast nature of relay stations to obtain diversity gain. Mesh topology is a more robust topology without increasing delay or decreasing throughput. Maximal ratio combining provides higher throughput per burst, together a total throughput is increase 5% per frame is achieved.

  • 75.
    Arias, Jahaivis M.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Privacy in the context of Smart Home Environments: Based upon a survey of experts2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Smart environments, particularly smart homes have become an increasingly popular topic for research and real world implementations. Despite the popularity of this topic, there is a lack of tools to enable inhabitants of smart environments to perceive which kind of data smart devices generate and to make inhabitants aware of who is accessing their personal information and the purpose for accessing this information. These issues have caused privacy concerns among inhabitants of smart environments – who would like to ensure their personal information is only utilized for their benefits, rather than being used for malicious purposes. Therefore, smart home environments motivate the need for privacy awareness tools to help inhabitants to better understand the privacy implications when their personal information is misused. To address this problem, this thesis suggests guidelines for the design of privacy awareness tools.

    A literature review evaluated instruments to conduct research about privacy concerns. The Internet Users’ Information Privacy Concerns (IUIPC) framework from Malhotra, Kim, and Agarwal was selected for the empirical part of this thesis project because it is one of the most reliable models developed to measure privacy concerns at the individual level. Quantitative data was gathered through a survey based on this framework. Data collected from 30 experts in the field of study was analyzed using linear regression analysis techniques and principal component analysis.

    These survey results lead to a set of guidelines that could guide designers and service providers as to what aspects of privacy concerns they should consider and what they should concentrate on when designing privacy awareness tools for ubiquitous computing systems, such as a smart home.

  • 76.
    Armendariz, Mikel
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Johansson, Christian
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Nordström, Lars
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Yunta Huete, Angel
    Unión Fenosa Distribución.
    García Lobo, Miguel
    Gas Natural Fenosa Engineering.
    A Method to Design Optimal Communication Architectures in Advanced Metering Infrastructures2017In: IET Generation, Transmission & Distribution, ISSN 1751-8687, E-ISSN 1751-8695, Vol. 11, no 2, 339-346 p.Article in journal (Refereed)
    Abstract [en]

    This paper proposes a method to determine the optimal communication architecture in advance metering infrastructures (AMI). The method starts by indicating suitable groups of meters that share similar characteristics such as distance to the secondary substation and mutual proximity. Then it connects each group of meters to the AMI-Head End through a communication architecture formed by wireless and Power Line Communication (PLC) technologies. The optimality criterion takes into account the Capital Expenditures (CAPEX), Operational Expenditures (OPEX) and the Quality of Service (QoS) in the communication architecture. The method is tested on a LV network based on real utility data provided by EU FP7 DISCERN project partners. These tests show that the method is consistent with planning foresight and can be useful to assist in the AMI communication architecture designing process.

  • 77.
    Arshad, Malik Wahaj
    et al.
    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.
    Västberg, Anders
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Edler, T.
    Energy efficiency gains through traffic offloading and traffic expansion in joint macro pico deployment2012In: 2012 IEEE Wireless Communications and Networking Conference, WCNC, IEEE Communications Society, 2012, 2203-2208 p.Conference paper (Refereed)
    Abstract [en]

    The traffic demand in future mobile cellular networks is expected to increase exponentially which would lead to dense base station deployment and eventually higher energy consumption. The current dominant mobile systems including GSM and UMTS were not designed with focus on energy efficiency. This paper investigates the energy saving potential of pico nodes in a heterogeneous network from an incumbent operator consideration. The results show that the number of hotspots and the user distribution in the hotspots strongly effects the power saving. Also, sleep modes in pico base stations have shown to reduce the energy loss to almost half. On a day average with limited utilization of pico base station, the heterogeneous network scenario provides marginal saving. The results also show that if the pico base station resources are fully utilized, premium user case, the heterogeneous network scenario can provide substantial reduction in energy per bit.

  • 78.
    Arshad, Malik Wahaj
    et al.
    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.
    Västberg, Anders
    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.
    Edler, T.
    Energy efficiency improvement through pico base stations for a green field operator2012In: IEEE Wireless Communications and Networking Conference, WCNC, IEEE Communications Society, 2012, 2197-2202 p.Conference paper (Refereed)
    Abstract [en]

    Mobile telecommunication operators are now focussing on emerging markets due to the current highly competitive mobile telecommunication sector in established markets. The deployment of wireless mobile infrastructure in these emerging markets or a green field scenario requires an innovative energy efficient approach, which is not feasible in an incumbent operator scenario. This paper describes a combined macro and pico cellular heterogeneous wireless network architecture, and analyses its energy efficiency with respect to variation in inter site distance. The increase in capacity and power saving through sparse network deployment is investigated in terms of area spectral efficiency and area power consumption respectively. The results suggest that the deployment of pico cells along with a traditional cellular network can improve the energy efficiency of the network, as well as provide gains in terms of increased inter site distance. Finally. the indifference curves of Energy Efficiency and number of pico nodes indicate the optimum deployment scheme for multiple area spectral efficiency targets.

  • 79.
    Arumugam Mathivanan, Arun
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    MiniSIP as a Plug-in2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Internet telephony has rapidly becoming an integral part of life. Due to its low incremental cost and the wide availability of voice over IP (VoIP) based services these services being used by nearly everyone. Today there are many VoIP applications available in the market, but most of them lack basic security features. Because people use VoIP services via public hotspots and shared local area networks these VoIP applications are vulnerable to attacks, such as eavesdropping. Today, there is a great need for VoIP applications with high quality security.

    MiniSIP is an open-source VoIP application platform, initially developed at KTH. High quality security has been a major focus of MiniSIP developments by several students, including the first public implementations of the secure real-time protocol (SRTP) and the Multimedia Key Exchange (MIKEY) protocol. MiniSIP implements secure end-to-end VoIP services. In addition, MiniSIP implements features such as dynamically choosing the most appropriate CODEC during a call, implementing calling policies, etc. However, it suffers from having a complicated GUI that requires the use of many libraries, rendering it both hard to build and hard support – both of which make it unsuitable for commercial purposes.

    Web browser plug-ins are shared libraries that users install to extend the functionality of their browser. For example, a plug-in can be used to display content that the browser itself cannot display natively. For example, Adobe's reader plugin displays PDF files directly within the web browser. Real Network’s Streaming video player utilizes a browser plug-in to provide support for live video streaming within a web page. Adobe’s Flash player plugin is required to load or view any Flash contents – such as video or animations.

    The goal of this thesis project is remove the problem of the existing MiniSIP GUIs by developing a Firefox browser plug-in for the MiniSIP application that will utilize a web-browser based GUI. The prototype that will be designed, implemented, and evaluated will implement an open-source VoIP application that is easy for a Firefox browser user to install and will be easy to use via a web interface. The long term goal is to facilitate an ordinary user to utilize VoIP communication via their web browser. A secondary goal is to re-use the code within MiniSIP, while using the web-browser to provide the GUI.

  • 80.
    Astély, David
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Ottersten, Björn
    KTH, Superseded Departments, Signals, Sensors and Systems.
    MLSE and Spatio-Temporal Interference Rejection Combining with Antenna Arrays1998In: Proceedings of Eusipco-98, Ninth European Signal Processing Conference, Island of Rhodes, Greece, 1998, 1341-1344 p.Conference paper (Refereed)
  • 81.
    Athanasiou, George
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Weeraddana, Pradeep Chathuranga
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Fischione, Carlo
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Orten, P.
    Communication infrastructures in industrial automation: The case of 60 GHz millimeterWave communications2013In: IEEE International Conference on Emerging Technologies and Factory Automation, ETFA, 2013Conference paper (Refereed)
    Abstract [en]

    Wireless sensor networks for industrial automation applications must offer timely, reliable, and energy efficient communications at both low and high data rate. While traditional communication technologies between 2.4 GHz and 5 GHz are sometimes incapable to efficiently achieve the aforementioned goals, new communication strategies are emerging, such as millimeterWave communications. In this overview paper, the general requirements that factory and process automation impose on the network design are reviewed. Moreover, this paper presents and qualitatively evaluates the 60 GHz millimeterWave communication technology for automation. It is argued that the upcoming 60 GHz millimeterWave technology brings an enormous potential and can influence the design of the future communication infrastructures in factory and process automation.

  • 82.
    Athanasiou, Georgios
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Weeraddana, Pradeep Chathuranga
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Fischione, Carlo
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Auction-Based Resource Allocation in MillimeterWave Wireless Access Networks2013In: IEEE Communications Letters, ISSN 1089-7798, Vol. 17, no 11, 2108-2111 p.Article in journal (Refereed)
    Abstract [en]

    The resource allocation problem of optimal assignment of the stations to the available access points in 60 GHz millimeterWave wireless access networks is investigated. The problem is posed as a multi-assignment optimization problem. The proposed solution method converts the initial problem to a minimum cost flow problem and allows to design an efficient algorithm by a combination of auction algorithms. The solution algorithm exploits the network optimization structure of the problem, and thus is much more powerful than computationally intensive general-purpose solvers. Theoretical and numerical results evince numerous properties, such as optimality, convergence, and scalability in comparison to existing approaches.

  • 83.
    Athanasiou, Georgios
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Weeraddana, Pradeep Chathuranga
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Fischione, Carlo
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Tassiulas, Leandros
    University of Thessaly, Volos, Greece.
    Optimizing Client Association for Load Balancing and Fairness in Millimeter Wave Wireless Networks2015In: IEEE/ACM Transactions on Networking, ISSN 1063-6692, E-ISSN 1558-2566, Vol. 23, no 3, 836-850 p.Article in journal (Refereed)
    Abstract [en]

    Millimeter-wave communications in the 60-GHz band are considered one of the key technologies for enabling multigigabit wireless access. However, the special characteristics of such a band pose major obstacles to the optimal utilization of the wireless resources, where the problem of efficient client association to access points (APs) is of vital importance. In this paper, the client association in 60-GHz wireless access networks is investigated. The AP utilization and the quality of the rapidly vanishing communication links are the control parameters. Because of the tricky non-convex and combinatorial nature of the client association optimization problem, a novel solution method is developed to guarantee balanced and fair resource allocation. A new distributed, lightweight, and easy-to-implement association algorithm, based on Lagrangian duality theory and subgradient methods, is proposed. It is shown that the algorithm is asymptotically optimal, that is, the relative duality gap diminishes to zero as the number of clients increases.

  • 84.
    Avesand (nee Sjöquist), Stefan
    KTH, Superseded Departments, Teleinformatics. KTH, School of Information and Communication Technology (ICT).
    Secure Database Access in Java Applets1998Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    For many years the web has only been used as a way ofdistributing information, but the need for more interaction isgrowing stronger. To accomplish this one can use Javaapplets, HTML forms, Active X, Javascript and a few othertechniques. One problem is that you must store the data theusers create, and change, somewhere and somehow. As thetitle reveals, this thesis will analyze a few ways to do this inJava applets.

  • 85.
    Avgeropoulos, Konstantinos
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Service Policy Management for User-Centric Services in Heterogeneous Mobile Networks,2004Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Session Initiation Protocol (SIP) is a signaling protocol for IP-based media services that will be the de facto standard for future media-over-IP services. Since SIP User Agents (UAs) support a limited number of service types (usually one or two), we assume that the future user will need to operate several UAs simultaneously. These UAs will constitute the user's personal service network. In this thesis, we investigate architectures for policy-based management of this network so that it can be used in an efficient manner. To achieve this, we propose a new SIP entity, called the SIP Service Manager (SSM), which lies in the core of the management system. Finally, we evaluate our proposal by implementing one version of the SIP Service Manager.

  • 86.
    Axberg, Stefan
    et al.
    Swedish National Defence College.
    Brynielsson, Joel
    Swedish National Defence College.
    Norsell, Martin
    Swedish National Defence College.
    A Sensor Concept for Superior Surveillance2007In: Proceedings of the Ninth International Symposium on Protection against Chemical and Biological Warfare Agents, 2007Conference paper (Refereed)
    Abstract [en]

    A highly developed aerial surveillance concept is presented. When fully implemented, the outlined surveillance system enhances situational awareness in two ways: it enhances the overall situational awareness in a large, possibly multinational, area and it provides the possibility to gain additional awareness in critical sites. The system is intended to be beneficial within various kinds of crisis management situations, e.g., disaster relief situations, humanitarian crises, chemical discharges, etc. In particular, the combination of large-area coverage with the possibility to instantly gain local situational awareness is believed to allow for pan-European collaboration and interoperability. Another targeted area includes critical ground sites such as ground transportation and infrastructure. The proposed concept uses surveillance at different altitudes and passes on near real-time information to a variety of end users through its embedded sensor and communications architecture.

  • 87.
    Ayrault, Cécile
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Service discovery for Personal Area Networks2004Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With the increasing use of electronic devices, the need for affordable wireless services specifically context-aware services, in a so-called Personal Area Network (PAN) is becoming an area with significant potential. Service discovery is a basic function.

    Even though a number of service discovery protocols have been implemented, a specific protocol for a PAN environment may need to be developed, as the characteristics of a PANs differ from other networking environments. Thus, the specific requirements for service discovery from a PAN perspective were studied. Methods for service discovery will be described that take into account both local and remote services.

    These methods will then be evaluated in a SIP telephony infrastructure to decide where a call should be delivered. The location of a person is done by using the implemented service discovery.

  • 88.
    Azari, Amin
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Energy Efficient Machine-Type Communications over Cellular Networks: A Battery Lifetime-Aware Cellular Network Design Framework2016Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Internet of Things (IoT) refers to the interconnection of uniquely identifiable smart devices which enables them to participate more actively in everyday life. Among large-scale applications, machine-type communications (MTC) supported by cellular networks will be one of the most important enablers for the success of IoT. The existing cellular infrastructure has been optimized for serving a small number of long-lived human-oriented communications (HoC) sessions, originated from smartphones whose batteries are charged in a daily basis. As a consequence, serving a massive number of non-rechargeable machine-type devices demanding a long battery lifetime is a big challenge for cellular networks.

    The present work is devoted to energy consumption modeling, battery lifetime analysis, and lifetime-aware network design for massive MTC services over cellular networks. At first, we present a realistic model for energy consumption of machine devices in cellular connectivity, which is employed subsequently in deriving the key performance indicator, i.e. network battery lifetime. Then, we develop an efficient mathematical foundation and algorithmic framework for lifetime-aware clustering design for serving a massive number of machine devices. Also, by extending the developed framework to non-clustered MTC, lifetime-aware uplink scheduling and power control solutions are derived. Finally, by investigating the delay, energy consumption, spectral efficiency, and battery lifetime tradeoffs in serving coexistence of HoC and MTC traffic, we explore the ways in which energy saving for the access network and quality of service for HoC traffic can be traded to prolong battery lifetime for machine devices.

    The numerical and simulation results show that the proposed solutions can provide substantial network lifetime improvement and network maintenance cost reduction in comparison with the existing approaches.

  • 89.
    Azari, Amin
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Energy-efficient scheduling and grouping for machine-type communications over cellular networks2016In: Ad hoc networks, ISSN 1570-8705, E-ISSN 1570-8713, Vol. 43, 16-29 p.Article in journal (Refereed)
    Abstract [en]

    In this paper, energy-efficient scheduling for grouped machine-type devices deployed in cellular networks isinvestigated. We introduce a scheduling-based cooperation incentivescheme which enables machine nodes to organize themselveslocally, create machine groups, and communicate through grouprepresentatives to the base station. This scheme benefits from anovel scheduler design which takes into account the cooperationlevel of each node, reimburses the extra energy consumptionsof group representatives, and maximizes the network lifetime.As reusing cellular uplink resources for communications insidethe groups degrades the Quality of Service (QoS) of theprimary users, analytical results are provided which present atradeoff between maximum allowable number of simultaneouslyactive machine groups in a given cell and QoS of the primaryusers. Furthermore, we extend our derived solutions for theexisting cellular networks, propose a cooperation-incentive LTEscheduler, and present our simulation results in the context ofLTE. The simulation results show that the proposed solutionssignificantly prolong the network lifetime. Also, it is shown thatunder certain circumstances, reusing uplink resource by machinedevices can degrade the outage performance of the primary userssignificantly, and hence, coexistence management of machinedevices and cellular users is of paramount importance for nextgenerations of cellular networks in order to enable group-basedmachine-type communications while guaranteeing QoS for theprimary users.

  • 90.
    Azari, Amin
    et al.
    Wireless Multimedia Communications Laboratory, Center of Excellence on Applied Electromagnetic Systems, University of Tehran, Iran .
    Harsini, Jalil
    Lahouti, Farshad
    Performance Analysis of Ad-Hoc Routing in Heterogeneous Clustered Multi-hop Wireless Networks2015In: Computer Networks, ISSN 1389-1286, E-ISSN 1872-7069, Vol. 80, 144-154 p.Article in journal (Refereed)
    Abstract [en]

    This paper analyzes the performance of clustered decode-and-forward multi-hop relaying (CDFMR) wireless Rayleigh fading networks, and sheds light on their design principles for energy and spectral efficiency. The focus is on a general performance analysis (over all SNR range) of heterogeneous wireless networks with possibly different numbers of relays in clusters of various separations. For clustered multi-hop relaying systems, hop-by-hop routing is known as an efficient decentralized routing algorithm which selects the best relay node in each hop using local channel state information. In this article, we combine hop-by-hop routing and cooperative diversity in CDFMR systems, and we derive (i) a closed-form expression for the probability distribution of the end-to-end SNR at the destination node; (ii) the system symbol error rate (SER) performance for a wide class of modulation schemes; and (iii) exact analytical expressions for the system ergodic capacity, the outage probability and the achievable probability of the SNR (power) gain. We also provide simple analytical asymptotic expressions for SER and the outage probability in high SNR regime. Numerical results are provided to validate the correctness of the presented analyses.

  • 91.
    Azari, Amin
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Battery Lifetime-Aware Base Station Sleeping Control with M2M/H2H Coexistence2016In: 2016 IEEE Global Communications Conference, GLOBECOM 2016 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2016, 7841624Conference paper (Refereed)
    Abstract [en]

    Fundamental tradeoffs in green cellular networkswith coexistence of machine-oriented and human-oriented trafficsare investigated. First, we present a queuing system to modelthe uplink transmission of a green base station which servestwo types of distinct traffics with strict requirements on delayand battery lifetime. Then, the energy-lifetime and energydelaytradeoffs are introduced, and closed-form expressions forenergy consumption of the base station, average experienceddelay in data transmission, and expected battery lifetime ofmachine devices are derived. Furthermore, we extend the derivedresults to the multi-cell scenario, and investigate the impacts ofsystem and traffic parameters on the energy-lifetime and energydelaytradeoffs using analytical and numerical results. Numericalresults show the impact of energy saving for the access network onthe introduced tradeoffs, and figure out the ways in which energycould be saved by compromising on the level of performance.

  • 92.
    Azari, Amin
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Energy Efficient MAC for Cellular-Based M2M Communications2014In: Signal and Information Processing (GlobalSIP), 2014 IEEE Global Conference on, IEEE conference proceedings, 2014, 128-132 p.Conference paper (Refereed)
    Abstract [en]

    In Machine-to-Machine (M2M) networks, an energyefficient scalable medium access control (MAC) is crucial forserving massive battery-driven machine-type devices. In thispaper, we investigate the energy efficient MAC design to minimizebattery power consumption in cellular-based M2M communications.We present an energy efficient MAC protocol that notonly adapts contention and reservation-based protocols for M2Mcommunications in cellular networks, but also benefits frompartial clustering to handle the massive access problem. Then weinvestigate the energy efficiency and access capacity of contentionbasedprotocols and present an energy efficient contention-basedprotocol for intra-cluster communication of the proposed MAC,which results in huge power saving. The simulation results showthat the proposed MAC protocol outperforms the others in energysaving without sacrificing much delay or throughput. Also, thelifetimes of both individual nodes and the whole M2M networkare significantly extended.

  • 93.
    Azari, Amin
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Fundamental Tradeoffs in Resource Provisioning forIoT Services over Cellular Networks2017In: Proceedings of the 2017 IEEE International Conference on Communications, Institute of Electrical and Electronics Engineers (IEEE), 2017, 7996885Conference paper (Refereed)
    Abstract [en]

    Performance tradeoffs in resource provisioningfor mixed internet-of-things (IoT) and human-orientedcommunications(HoC) services over cellular networks are investigated.First, we present a low-complexity model of cellularconnectivity in the uplink direction in which both accessreservation and scheduled data transmission procedures areincluded. This model is employed subsequently in derivinganalytical expressions for energy efficiency, spectral efficiency,and experienced delay in data transmission of connected devicesas well as energy consumption of base stations. The derivedexpressions indicate that the choice of uplink resource provisioningstrategy introduces tradeoffs between battery lifetime forIoT communications, quality of service (QoS) for HoC, spectralefficiency and energy consumption for the access network. Then,the impacts of system and traffic parameters on the introducedtradeoffs are investigated. Performance analysis illustrates thatimproper resource provisioning for IoT traffic not only degradesQoS of high-priority services and decreases battery lifetime ofIoT devices, but also increases energy consumption of the accessnetwork. The presented analytical and simulations results figureout the ways in which spectral/energy efficiency for the accessnetwork and QoS for high-priority services could be traded toprolong battery lifetimes of connected devices by compromisingon the level of provisioned radio resources.

  • 94.
    Azari, Amin
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Lifetime-Aware Scheduling and Power Control for Cellular-based M2M Communications2015In: Wireless Communications and Networking Conference (WCNC), 2015 IEEE: , IEEE conference proceedings, 2015, 1171-1176 p.Conference paper (Refereed)
    Abstract [en]

    In this paper the uplink scheduling and transmit powercontrol is investigated to minimize the energy consumption forbattery-driven devices deployed in cellular networks. A lifetimemetric based on the accurate energy consumption model for cellularbasedmachine devices is provided and used to formulate theuplink scheduling and power control problems as network lifetimemaximization problems. Then, lifetime-aware uplink scheduling andpower control protocols which maximize the overall network lifetimeare investigated based on the different lifetime definitions. Besidesthe exact solutions, the low-complexity suboptimal solutions arepresented in this work which can achieve near optimal performancewith much lower computational complexity. The performance evaluationshows that the network lifetime is significantly extended underproposed protocols.

  • 95.
    Azari, Amin
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Lifetime-Aware Scheduling and Power Control for M2M Communications in LTE Networks2015In: Vehicular Technology Conference (VTC Spring), 2015 IEEE 81st, IEEE conference proceedings, 2015Conference paper (Refereed)
    Abstract [en]

    In this paper the scheduling and transmit powercontrol are investigated to minimize the energy consumptionfor battery-driven devices deployed in LTE networks. To enableefficient scheduling for a massive number of machine-typesubscribers, a novel distributed scheme is proposed to let machinenodes form local clusters and communicate with the base-stationthrough the cluster-heads. Then, uplink scheduling and powercontrol in LTE networks are introduced and lifetime-aware solu-tions are investigated to be used for the communication betweencluster-heads and the base-station. Beside the exact solutions,low-complexity suboptimal solutions are presented in this workwhich can achieve near optimal performance with much lowercomputational complexity. The performance evaluation showsthat the network lifetime is significantly extended using theproposed protocols.

  • 96.
    Azari, Amin
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Network Lifetime Maximization for Cellular-Based M2M Networks2017In: IEEE Access, E-ISSN 2169-3536Article in journal (Refereed)
    Abstract [en]

    High energy efficiency is critical for enabling massivemachine-type communications (MTC) over cellular networks.This work is devoted to energy consumption modeling,battery lifetime analysis, lifetime-aware scheduling and transmitpower control for massive MTC over cellular networks. Weconsider a realistic energy consumption model for MTC andmodel network battery-lifetime. Analytic expressions are derivedto demonstrate the impact of scheduling on both the individualand network battery lifetimes. The derived expressions aresubsequently employed in uplink scheduling and transmit powercontrol for mixed-priority MTC traffic in order to maximizethe network lifetime. Besides the main solutions, low-complexitysolutions with limited feedback requirement are investigated,and the results are extended to existing LTE networks. Also,the energy efficiency, spectral efficiency, and network lifetimetradeoffs in resource provisioning and scheduling for MTC overcellular networks are investigated. The simulation results showthat the proposed solutions can provide substantial networklifetime improvement and network maintenance cost reductionin comparison with the existing scheduling schemes.

  • 97.
    Azfar, Abdullah
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Multiple Escrow Agents in VoIP2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Using a Key escrow agent in conjunction with Voice over IP (VoIP) communication ensures that law enforcements agencies (LEAs) can retrieve the session key used to encrypt data between two users in a VoIP session. However, the use of a single escrow agent has some drawbacks. A fraudulent request by an evil employee from the LEA can lead to improper disclosure of a session key. After the escrow agent reveals the key this evil person could fabricate data according to his/her needs and encrypt it again (using the correct session key). In this situation the persons involved in the communication session can be accused of crimes that he or she or they never committed. The problems with a single escrow agent becomes even more critical as a failure of the escrow agent can delay or even make it impossible to reveal the session key, thus the escrow agent might not be able to comply with a lawful court order or comply with their escrow agreement in the case of data being released according to this agreement (for example for disaster recovery).

    This thesis project focused on improving the accessibility and reliability of escrow agents, while providing good security. One such method is based on dividing the session key into M chunks and escrowing the chunks with M escrow agents. Using threshold cryptography the key can be regenerated by gathering any N-out-of-M chunks. The value of M and N may differ according to the role of the user. For a highly sophisticated session, the user might define a higher value for M and N for improved, availability, reliability, and security. For a less confidential or less important session (call), the value of M and N might be smaller. The thesis examines the increased availability and increased reliability made possible by using multiple escrow agents.

  • 98.
    Azzolin de Carvalho Pires, Gustavo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Multi-Cell Admission Control for WCDMA Networks2006Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    It has long been recognized that in multi-cell WCDMA networks the admission of a new session into the system can have undesirable impact on the neighboring cells. Although admission control algorithms that take into account such multi-cell impact have been studied in the past, little attention has been paid to multi-cell admission and rate control algorithms when traffic is elastic. In this thesis, we propose a model for multi-cell multi-service WCDMA networks to study the impact of multi-cell admission and rate control algorithms on key performance measures such as the class-wise blocking and outage probabilities, block error rates, and the noise rise violation probabilities. By means of simulation we compare the performance of load based multi-cell algorithms with that of a single cell algorithm. We find that with multi-cell based algorithms the system capacity and performance (in terms of the above mentioned measures) are (in some cases significantly) better in homogeneous load scenarios as well as in the heterogeneous ’hotspot’ and ’hotaround’ scenarios.

  • 99.
    B. da Silva Jr., Jose Mairton
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Fodor, Gabor
    KTH, School of Electrical Engineering (EES), Automatic Control. Ericsson Research.
    Fischione, Carlo
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Spectral Efficient and Fair User Pairing for Full-Duplex Communication in Cellular Networks2016In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 15, no 11, 7578-7593 p.Article in journal (Refereed)
    Abstract [en]

    —A promising new transmission mode in cellular networks is the three-node full-duplex mode, which involves a base station with full-duplex capability and two half-duplex user transmissions on the same frequency channel for uplink and downlink. The three-node full-duplex mode can increase spectral efficiency, especially in the low transmit power regime, without requiring full-duplex capability at user devices. However, when a large set of users is scheduled in this mode, self-interference at the base station and user-to-user interference can substantially hinder the potential gains of full-duplex communications. This paper investigates the problem of grouping users to pairs and assigning frequency channels to each pair in a spectral efficient and fair manner. Specifically, the joint problem of user uplink/downlink frequency channel pairing and power allocation is formulated as a mixed integer nonlinear problem that is solved by a novel joint fairness assignment maximization algorithm. Realistic system level simulations indicate that the spectral efficiency of the users having the lowest spectral efficiency is increased by the proposed algorithm, while a high ratio of connected users in different loads and self-interference levels is maintained.

  • 100. Babaheidarian, P.
    et al.
    Salimi, S.
    Papadimitratos, Panagiotis
    KTH, School of Electrical Engineering (EES), Network and Systems engineering.
    Preserving confidentiality in the Gaussian broadcast channel using compute-and-forward2017In: 2017 51st Annual Conference on Information Sciences and Systems, CISS 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, 7926077Conference paper (Refereed)
    Abstract [en]

    We study the transmission of confidential messages across a wireless broadcast channel with K > 2 receivers and K helpers. The goal is to transmit all messages reliably to their intended receivers while keeping them confidential from the unintended receivers. We design a codebook based on nested lattice structure, cooperative jamming, lattice alignment, and i.i.d. coding. Moreover, we exploit the asymmetric compute-and-forward decoding strategy to handle finite SNR regimes. Unlike previous alignment schemes, our achievable rates are attainable at any finite SNR value. Also, we show that our scheme achieves the optimal sum secure degrees of freedom of 1 for the K-receiver Gaussian broadcast channel with K confidential messages and K helpers.

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