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  • 101.
    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.

  • 102. 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.

  • 103.
    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.

  • 104.
    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.

  • 105.
    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.

  • 106.
    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.

  • 107.
    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.

  • 108. 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.

  • 109.
    Appelgren, Filiph
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Power System Software Development: with possible SCADA System Integration2014Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In order for power system operators (such as TRANSCO) to maintain and operatethe transmission grid in a safe, secure and effcient way, automatic tools such asSCADA systems is necessary to meet demand at all times. The main purpose of thisthesis was to develop a software/prototype at the load despatch centre at TRANSCOwith the ability to monitor and communicate with power plants. The software issupposed to work in a real-time electronic market. The power plant operators candeclare their availability and capability parameters of their generating and producingunits to TRANSCO and LDC operators can send load despatch instructions to thepower plants (such as load changes and other ancillary instructions). The prototypealso has a compliance monitoring application that validates unit outputs againstdespatched instructions. If the output is outside a specific interval, a transgressionwarning is sent to the power plant informing them that they should adjust their unitoutput against the target load. If further transgression is continued, the operator atLDC can re-declare the units availability on the power plants behalf and issue a newload despatch instruction to the unit. The re-declared availability level will be valid allthe way back to when the unit issued the last availability declaration.The software was successfully developed and could perform all tasks that it wassupposed to in a satisfactory way. In order to make the development as sufficient andeffective as possible, a "dummy" power plant was created and was used to simulateunit outputs and plant operator behaviour. As the time was too short, the SCADAintegration was never investigated and was left to whom is taken over after this thesishas ended.

  • 110. Aramrattana, Maytheewat
    et al.
    Larsson, Tony
    Jansson, Jonas
    Dimensions of Cooperative Driving, ITS and Automation2015In: Intelligent Vehicles Symposium (IV), 2015Conference paper (Other academic)
  • 111.
    Aramrattana, Maytheewat
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES). The Swedish National Road and Transport Research Institute (VTI), Linköping, Sweden.
    Larsson, Tony
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Jansson, Jonas
    The Swedish National Road and Transport Research Institute (VTI), Linköping, Sweden.
    Nåbo, Arne
    The Swedish National Road and Transport Research Institute (VTI), Linköping, Sweden.
    Extended Driving Simulator for Evaluation of Cooperative Intelligent Transport Systems2016In: SIGSIM-PADS '16: Proceedings of the 2016 annual ACM Conference on SIGSIM Principles of Advanced Discrete Simulation, New York: ACM Digital Library, 2016, 255-278 p.Conference paper (Refereed)
    Abstract [en]

    Vehicles in cooperative intelligent transport systems (C-ITS) often need to interact with each other in order to achieve their goals, safe and efficient transport services. Since human drivers are still expected to be involved in C-ITS, driving simulators are appropriate tools for evaluation of the C-ITS functions. However, driving simulators often simplify the interactions or influences from the ego vehicle on the traffic. Moreover, they normally do not support vehicle-to-vehicle and vehicle-to-infrastructure (V2X) communication, which is the main enabler for C-ITS. Therefore, to increase the C-ITS evaluation capability, a solution on how to extend a driving simulator with traffic and network simulators to handle cooperative systems is presented as a result of this paper. Evaluation of the result using two use cases is presented. And, the observed limitations and challenges of the solution are reported and discussed. © 2016 ACM, Inc.

  • 112.
    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.

  • 113.
    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.

  • 114.
    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.

  • 115.
    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.

  • 116.
    Aria, Erfan
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Investigation of automated vehicle effects on driver’s behavior and traffic performance2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Advanced Driver Assistance Systems (ADAS) offer the possibility of helping drivers to fulfill their driving tasks. Automated vehicles are capable of communicating with surrounding vehicles (V2V) and infrastructure (V2I) in order to collect and provide essential information about driving environment. Studies have proved that automated vehicles have a potential to decrease traffic congestion on road networks by reducing the time headway, enhancing the traffic capacity and improving the safety margins in car following. Furthermore, vehicle movement and driver’s behavior of conventional vehicles will be affected by the presence of automated vehicles in traffic networks. Despite different encouraging factors, automated driving raises some concerns such as possible loss of situation awareness, overreliance on automation and degrading driving skills in absence of practice. Moreover, coping with complex scenarios, such as merging at ramps and overtaking, in terms of interaction between automated vehicles and conventional vehicles need more research. This thesis work aims to investigate the effects of automated vehicles on driver’s behavior and traffic performance. A broad literature review in the area of driving simulators and psychological studies was performed to examine the automated vehicle effects on driver’s behavior. Findings from the literature survey, which has been served as setup values in the simulation study of the current work, reveal that the conventional vehicles, which are driving close to the platoon of automated vehicles with short time headway, tend to reduce their time headway and spend more time under their critical time headway. Additionally, driving highly automated vehicles is tedious in a long run, reduce situation awareness and can intensify driver drowsiness, exclusively in light traffic. In order to investigate the influences of automated vehicles on traffic performance, a microscopic simulation case study consisting of different penetration rates of automated vehicles (0, 50 and 100 percentages) was conducted in VISSIM software. The scenario network is a three-lane autobahn segment of 2.9 kilometers including an off-ramp, on-ramp and a roundabout with some surrounding urban roads. Outputs of the microscopic simulation in this study reveal that the positive effects of automated vehicles on roads are especially highlighted when the network is crowded (e.g. peak hours). This can definitely count as a constructive point for the future of road networks with higher demands. In details, average density of autobahn segment remarkably decreased by 8.09% during p.m. peak hours in scenario with automated vehicles. Besides, Smoother traffic flow with less queue in the weaving segment was observed. Result of the scenario with 50% share of automated vehicles moreover shows a feasible interaction between conventional vehicles and automated vehicles. Meaningful outputs of this case study, based on the input data from literature review, demonstrate the capability of VISSIM software to simulate the presence of automated vehicles in great extent, not only as an automated vehicle scenario but also a share of them, in traffic network. The validity of the output values nonetheless needs future research work on urban and rural roads with different traffic conditions.

  • 117.
    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.

  • 118.
    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.

  • 119.
    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.

  • 120.
    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.

  • 121.
    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.

  • 122.
    Arvanitaki, Antonia
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Modeling of a UAV-based Data Collection System2017In: IEEE 22nd International Workshop on Computer Aided Modeling and Design of Communication Links and Networks (CAMAD), Lund, Sweden, 2017Conference paper (Refereed)
  • 123.
    Arvidsson, Anna K
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Lundberg, Thomas
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Test av korrektionstjänst för GPS-mottagare vid vägytemätning2012Report (Other academic)
    Abstract [en]

    An important factor in the inventory of the road network condition is to be able to geographically position the measurement data at the right place with sufficient accuracy.

    In March 2012, the correction service EPOS, used to provide an improved positioning, was shut down. By the commission of the Swedish Transport Administration, VTI has evaluated whether the free correction service EGNOS, operated by ESA, is possible to be used instead. The answer is yes. No systematic differences in the position data could be observed when using the old and the new correction service.

  • 124.
    Arvidsson, Simon
    et al.
    Linköping University, Department of Computer and Information Science.
    Ekblom, Tobias
    Linköping University, Department of Computer and Information Science.
    Marknadsplatsapplikation för Android2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Målet med examensarbetet är att utveckla en marknadsplatsapplikation för Android. Marknadsplatsapplikationen ska tillhandahålla funktioner för att ge användaren förutsättningar att hitta och ladda ner applikationer över Internet ifrån marknadsplatsens serversida. Marknadsplatsapplikationen kommer likt en tunn klient vara helt beroende av innehåll från en serversida. Vid examensarbetets utförande existerade dock ingen serversida då denna ännu inte var färdigutvecklad.

    För att utveckla marknadsplatsapplikationen utan närvaron av en serversida, implementerades en emulerad serversida som utåt sett hade funktionaliteten av en framtida serversida. En mjukvaruarkitektur implementerades bestående av tre lager: användargränsnitt (GUI), kärnfunktionalitet (Core) och webbkommunikation (WebCom). Syftet med arikitekturen var dels att begränsa inverkan av övergången från en emulerad serversida till en riktig serversida, och dels att avgränsa och avlasta användargränsnittet från tunga operationer för att därigenom uppnå god responsivitet.

    Marknadsplatsapplikationen implementerades med all funktionalitet som planerades. Arkitekturen med tydlig separation mellan GUI, Core ochWebCom, förväntas leda till en smidig övergång till en riktig serversida. Även ett tydligt öde för att hämta och skicka data mellan marknadsplatsapplikationen och serversida förväntas underlätta att implementera ny funktionalitet som är beroende av en serversida. Användargränsnittet uppvisar fortfarande brist på responsivitet. Arkitekturen med endast en asynkron klass GuiWorker, som hanterar exekveringen av tunga operationer på bakgrundstrådar, förväntas dock kunna uppnå ett responsivt användargränsnitt.

  • 125. Arvidsson, Åke
    et al.
    Rydén, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Load transients in pooled cellular core network nodes2015In: Performance evaluation (Print), ISSN 0166-5316, E-ISSN 1872-745X, Vol. 90, 18-35 p.Article in journal (Refereed)
  • 126.
    Ashjaei, Mohammad
    Mälardalen University, School of Innovation, Design and Engineering. Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Multi-Hop Real-Time Communication over Switched Ethernet Technology2014Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Switched Ethernet technology has been introduced to be exploited in real-time communication systems due to its features such as its high throughput and wide availability, hence being a cost-effective solution. Many real-time switched Ethernet protocols have been developed, preserving the profits of traditional Ethernet technology, to overcome the limitations imposed by using commercially available (COTS) switches. These limitations mainly originate from the non-deterministic behavior of the Ethernet switches inherent in the use of FIFO queues and a limited number of priority levels.

     

    In our research we focus on two particular real-time communication technologies, one based on COTS Ethernet switches named the FTT-SE architecture and the other using a modified Ethernet switch called the HaRTES architecture. Both architectures are based on a master-slave technique supporting different and temporally isolated traffic types including real-time periodic, real-time sporadic and non-real-time traffic. Also, they provide mechanisms implementing adaptivity as a response to the requirements imposed by dynamic real-time applications. Nevertheless, the two mentioned architectures were originally developed for a simple network consisting of a single switch, and they were lacking support for multi-hop communication. In industrial applications, multi-hop communication is essential as the networks comprise a high number of nodes, that is far beyond the capability of a single switch.

     

    In this thesis, we study the challenges of building multi-hop communication using the FTT-SE and the HaRTES architectures. We propose different architectures to provide multi-hop communication while preserving the key characteristics of the single-switch architecture such as timeliness guarantee, resource efficiency, adaptivity and dynamicity. We develop a response time analysis for each proposed architecture and we compare them to assess their corresponding benefits and limitations. Further, we develop a simulation tool to evaluate the solutions.

  • 127.
    Aspnäs, Frida
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Eliminating Right-Turn-on-Red (RTOR) at Key Intersections in a City Core2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The City of Fredericton is the capital of New Brunswick, located in eastern Canada. Rightturn-on-red (RTOR) is a general practice at any traffic intersection in this maritime province. Many collisions between pedestrians and vehicles have been recorded at signalized intersections in the downtown area of the city. Due to the number of collisions, the City of Fredericton was interested in investigating how a restriction against RTOR could affect vehicular traffic. The purpose and goal of this project was to develop a calibrated traffic model of the downtown area of Fredericton that could be used for simulation studies. Two main changes were investigated: 1) a restriction against RTOR for each of eleven key intersections in the downtown area, and 2) a restriction against left-turns at one selected intersection. The traffic simulation model was also used for analyzing how factors such as pedestrian volumes, lane channelization, and turning proportions affect the changes in traffic conditions due to permitting, or prohibiting, right-turn-on-red.

    The traffic simulation model was created in the TSIS/CORSIM software. Several different scenarios were generated for analysis. The results of the simulation show that the traffic conditions in the whole downtown area will be affected when introducing a restriction against RTOR. Certain intersections show a relatively high change while others show no significant change at all. Several different factors were seen to affect the number of RTOR that could be performed at an intersection. One main factor was lane channelization. With a shared lane, the proportion of right-turning vehicles at the intersection was found to highly affect how many RTOR can be performed. Pedestrian volumes prove to be a third factor affecting the number of RTOR at an intersection.

    Overall results demonstrate that there are only a few intersections where it is suitable for the City of Fredericton to implement a restriction against RTOR.

  • 128.
    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)
  • 129.
    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.

  • 130.
    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, E-ISSN 1558-2558, 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.

  • 131.
    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.

  • 132.
    Atiiq, Syafiq Al
    KTH, School of Electrical Engineering (EES), Network and Systems engineering.
    Adaptive Counteraction Against Denial of Service Attack2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Internet of Things (IoT) is the next generation of networked society where billions of, everyday-life, devices are directly connected to the Internet and able to communicate with each other. In particular, the Constrained Application Protocol (CoAP) has become the de-facto IoT standard for communication at the application layer, as a lightweight web transfer protocol affordable also for resource-constrained platforms. However, as IoT devices are directly connected to the Internet, they are especially vulnerable to a number of security attacks including Denial of Service (DoS), which can seriously worsen their performance and responsiveness, and even make them totally unavailable to serve legitimate requests.

    In this Master's Thesis project, we have developed a cross-layer and context-aware approach that adaptively counteracts DoS attacks against CoAP server devices, by dynamically adjusting their operative state according to the attack intensity. This considerably limits the impact of DoS attacks and preserves service availability of victim devices to the best possible extent. The proposed approach leverages a trusted Proxy that adaptively shields victim devices, while effectively forwarding and caching messages if needed. We have made a proof-of-concept implementation of our solution for the Californium framework and the CoAP protocol, and experimentally evaluated its effectiveness in counteracting DoS and preserving availability of devices under attack.

    This Master's Thesis project has been conducted in collaboration with RISE SICS, a research institute for applied information and communication technology in Sweden.

  • 133.
    Augustine, Robin
    Uppsala University.
    BAN Antenna Design Using Ferrite Polymer Composite2009Conference paper (Refereed)
  • 134.
    Augustine, Robin
    Uppsala University.
    Biocompatibility study of biphasic-chitosan-soyameal composite Bioceramic Implants and their use as Phantoms for Medical Imaging. Applications2008Conference paper (Refereed)
  • 135. Augustine, Robin
    Biocompatibility study of hydroxy apatite and chitosan composites for applications at microwave frequencies2010In: Microwave and optical technology letters (Print), ISSN 0895-2477, E-ISSN 1098-2760, Vol. 46, no 3, 197-199 p.Article in journal (Refereed)
    Abstract [en]

    Hydroxyapatite (HAp, Ca10(PO4)6(OH)2) bioceramic and chitosan (poly [(β-1-4) d-glucosamine]) biopolymer show good biocompatibility in vivo. They have biological origin and show excellent interactions with microwave. Microwave study of HAp made using different drying techniques and their composites with chitosan in the ISM band is presented. Pastes are made using HAp and chitosan with different ratios of mixing. The dielectric properties of this composites match with that of human fat, collagen tissues. Some of the compositions exhibit dielectric property close to that of natural bone. This makes them more biocompatible and better substitutes for natural bone. Thus composite bioceramics can be considered as phantom model constituents for imaging purposes. Their dielectric properties prove that they are biocompatible. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2931–2934, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23806

  • 136.
    Augustine, Robin
    Uppsala University.
    Dielectric Studies of Calcium Hydroxyapatite at Microwave Frequency2005Conference paper (Refereed)
  • 137. Augustine, Robin
    Développement d’un modèle humain dans la bande millimétrique pour les applications2011Conference paper (Refereed)
  • 138.
    Augustine, Robin
    Université Paris-Est.
    Electromagnetic modelling of human tissues and its application on the interaction between antenna and human body in the BAN context2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this age of wireless technology, Body Area networks (BAN) is revolutionising the concept of patient care and health monitoring. BAN provides people good assessment of their health status at any time, wherever they are physically. The increased interest in developing effective body (in, on & off) communication systems made phantoms which can mimic the electrical properties of an actual human body necessary. Wearable antennas which are the indispensable part of BAN got to be low pro file and above all influences that human body can make. There should also be a way to reduce the effect of antennas on human body namely specific absorption rate (SAR). In this work effort has been made to develop phantoms suitable for both On body and In body communications. The base materials which are selected for the study are of biological origin (bio ceramics and biopolymers) whose behaviour is closer to that of human tissues. As these phantoms are biocompatible they are essentially non toxic where the conventionally available phantoms are toxic in nature. Different kinds of low profile conformal wearable antennas working at 2.4GHz ISM band were developed and studied in the BAN perspective. Antennas suffer much in terms of matching and efficiency when they are in contact or in the premises of human body. This is a major hurdle in the way to setting up a good body communication network. This work encompasses various techniques adopted to limit the body interferences to an acceptable level. The techniques adopted (Such as Backing Ground Plane, High Impedance Surface & Polymeric Ferrite Sheets) proved to be effective in reducing the sway in antenna characteristics when they are mounted on body. Specific absorption rate is also brought to acceptable levels and thus avoiding the formation of hot spots due to microwave absorption. A safer and cost effective BAN can be set up using this work which will lead to a safer, mobile and healthy future.

  • 139. Augustine, Robin
    Permittivity Spectra of Biological Solutions in the Millimeter-Wave Range at Room andHuman Body Temperatures2011Conference paper (Refereed)
  • 140.
    Augustine, Robin
    Uppsala University.
    SAR reduction of wearable antennas using polymeric ferrite sheets2010Conference paper (Refereed)
  • 141.
    Augustine, Robin
    Uppsala University.
    Topology Optimization of Wideband Directive Antennas2015In: Progress in Electromagnetics Research, Vol. 2A1, no SC4, 636-639 p.Article in journal (Refereed)
  • 142.
    Augustine, Robin
    Uppsala University.
    Wide Band Impedance matching For Transducers2005Conference paper (Refereed)
  • 143. Augustine, Robin
    et al.
    Thierry, Alves
    Sarrebourse, T.
    Poussot, B.
    Mathew, K. T.
    Laheurte, J. -M.
    Polymeric ferrite sheats for SAR reduction of Wearable ANtennas2010In: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 46, no 3, 197-198 p.Article in journal (Refereed)
    Abstract [en]

    Reduction of specific absorption rate (SAR) has now become a buzz word because of the growing health concerns over microwave exposure. Ferrites are found to be effective in diminishing electromagnetic influence. In this reported work, flexible polymeric ferrite sheets are characterised on the basis of their shielding efficiencies. SAR measurements are carried out with a planar wearable antenna and polymeric ferrite shielding to confirm its competence.

  • 144.
    Aujla, Gagangeet Singh
    et al.
    Thapar University, Patiala, India.
    Chaudhary, Rajat
    Thapar University, Patiala, India.
    Kumar, Neeraj
    Thapar University, Patiala, India.
    Rodrigues, Joel J. P. C.
    National Institute of Telecommunications (Inatel), Santa Rita do Sapucaí, Brazil; University of Beira Interior, Covilhã, Portugal; ITMO University, St. Petersburg, Russia; University of Fortaleza (Unifor), Fortaleza, Brazil.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Data Offloading in 5G-Enabled Software-Defined Vehicular Networks: A Stackelberg-Game-Based Approach2017In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 55, no 8, 100-108 p.Article in journal (Refereed)
    Abstract [en]

    Data offloading using vehicles is one of the most challenging tasks to perform due to the high mobility of vehicles. There are many solutions available for this purpose, but due to the inefficient management of data along with the control decisions, these solutions are not adequate to provide data offloading by making use of the available networks. Moreover, with the advent of 5G and related technologies, there is a need to cope with high speed and traffic congestion in the existing infrastructure used for data offloading. Hence, to make intelligent decisions for data offloading, an SDN-based scheme is presented in this article. In the proposed scheme, an SDNbased controller is designed that makes decisions for data offloading by using the priority manager and load balancer. Using these two managers in SDN-based controllers, traffic routing is managed efficiently even with an increase in the size of the network. Moreover, a single-leader multi-follower Stackelberg game for network selection is also used for data offloading. The proposed scheme is evaluated with respect to several parameters where its performance was found to be superior in comparison to the existing schemes. © Copyright 2017 IEEE

  • 145.
    Avazkonandeh Gharavol, Ebrahim
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    Larsson, Erik G.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    Robust Joint Optimization of MIMO Interfering Relay Channels with Imperfect CSI2011In: 2001 4th IEEE International Workshop on Computational Advances in Multi-Sensor Adaptive Processing (CAMSAP), Piscataway, NJ, USA: IEEE , 2011, , 5 p.209-212 p.Conference paper (Refereed)
    Abstract [en]

    In this paper we deal with the problem of the joint optimization of the precoders, equalizers and relay beamformer of a multiple-input multiple-output interfering relay channel. This network can be regarded az a generalized model for both one-way and two-way relay channels with/without direct interfering links. Unlike the conventional design procedures, we assume that the Channel State Information (CSI) is not known perfectly. The imperfect CSI is described using the norm bounded error framework. We use a system-wide Sum Mean Square Error (SMSE) based problem formulation which is constrained using the transmit power of the terminals and the relay node. The problem at hand, from a worst-case design perspective, is a multilinear, and hence, a nonconvex problem which is also semiinfinite in its constraints. We use a generalized version of the Peterson’s lemma to handle the semi-infiniteness and reduce the original problem to a single Linear Matrix Inequality (LMI). However, this LMI is not convex, and to resolve this issue we propose an iterative algorithm based on the alternating convex search methodology to solve the aforementioned problem. Finally simulation results, i.e., the convergence of the proposed algorithm and the SMSE properties, are included to asses the performance of the proposed algorithm.

  • 146.
    Avazkonandeh Gharavol, Ebrahim
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    Larsson, Erik G.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    Robust Joint Optimization of Non-regenerative MIMO Relay Channels with Imperfect CSI2011In: Conference Record of the Forty Fifth Asilomar Conference on Signals, Systems and Computers (ASILOMAR), 2011, IEEE Computer Society, 2011, 1589-1593 p.Conference paper (Refereed)
    Abstract [en]

    In this paper, we deal with the problem of joint optimization of the source precoder, the relay beamformer and the destination equalizer in a nonregenerative relay network with only a partial knowledge of the Channel State Information (CSI).

    We model the partial CSI using a deterministic norm bounded error model, and we use a system-wide mean square error performance measure which is constrained based on the transmit power regulations for both source and relay nodes.

    Most conventional designs employ the average performance optimization, however, we solve this problem from a worst-case design perspective.

    The original problem formulation is a semi-infinite trilinear optimization problem which is not convex.

    To solve this problem we extend the existing theories to deal with the constraints which are semi-infinite in different independent complex matrix variables.

    We show that the equivalent approximate problem is a set of linear matrix inequalities, that can be solved iteratively.

    Finally simulation results assess the performance of the proposed scheme.

  • 147.
    Avazkonandeh Gharavol, Ebrahim
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    Larsson, Erik G.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    The Sign-Definiteness Lemma and Its Applications to Robust Transceiver Optimization for Multiuser MIMO Systems2013In: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 61, no 2, 238-252 p.Article in journal (Refereed)
    Abstract [en]

    We formally generalize the sign-definiteness lemma to the case of complex-valued matrices and multiple norm-bounded uncertainties. This lemma has found many applications in the study of the stability of control systems, and in the design and optimization of robust transceivers in communications. We then present three different novel applications of this lemma in the area of multi-user multiple-input multiple-output (MIMO) robust transceiver optimization. Specifically, the scenarios of interest are: (i) robust linear beamforming in an interfering adhoc network, (ii) robust design of a general relay network, including the two-way relay channel as a special case, and (iii) a half-duplex one-way relay system with multiple relays. For these networks, we formulate the design problems of minimizing the (sum) MSE of the symbol detection subject to different average power budget constraints. We show that these design problems are non-convex (with bilinear or trilinear constraints) and semiinfinite in multiple independent uncertainty matrix-valued variables. We propose a two-stage solution where in the first step the semi-infinite constraints are converted to linear matrix inequalities using the generalized signdefiniteness lemma, and in the second step, we use an iterative algorithm based on alternating convex search (ACS). Via simulations we evaluate the performance of the proposed scheme.

  • 148.
    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.

  • 149.
    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.

  • 150.
    Avgouleas, Ioannis
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    IoT Networking Resource Allocation and Cooperation2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The Internet of Things (IoT) promises that "anything that can be connected, will be connected". It comprises of Information and Communication Technologies that interconnect billions of physical and visual things with some "basic" intelligence. The emerging IoT services will be able to react with minimal human intervention and further contribute to the big data era that requires real-time, ultrareliable, ubiquitous, scalable, and heterogeneous operation.

    This thesis is the result of our investigations on problems dealing with the evolution of such technologies. First, we explore the potential of using relay i.e., intermediate, nodes that assist users to transmit their packets in a a cellular network. Paper I provides insights into how adapting the cooperation of the relay's receiver and transmitter optimizes the network-wide throughput while the relay's queue stability is guaranteed.

    The next part of the thesis copes with the resource allocation of services on IoT devices equipped with multiple network interfaces. The resources are heterogeneous and can be split among dierent interfaces. Additionally, they are not interchangeable. In paper II, we develop optimization models for this resource allocation problem, prove the complexity of the models, and derive results that give intuition into the problems. Moreover, we propose algorithms that approximate the optimal solution and show under which circumstances this is possible.

    Finally, in paper III, we present a resource allocation problem specically for smart cities services. In comparison to the previous problem denition, resources are of one type but the IoT network device can oer capacities that vary over time. Furthermore, services have a tolerance regarding their preferred scheduling, namely, their allocation over time. We parametrize each service with a pricing function to indicate its tolerance to be served at the beginning of the scheduling window. We prove that the problem is computationally hard and provide numerical results to gain insight into how different pricing weight functions impact the allocations' distribution within the scheduling window.

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