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  • 801.
    Wennlund, Andreas
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Context-aware Wearable Device for Reconfigurable Application Networks2003Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Context information available in wearable devices is believed to be useful in many ways. It allows for hiding much of the complexity from the user, thus enabling simpler user interfaces and less user interaction when carrying out tasks on behalf of a user, as well as enabling network operators to provide a better interface to thirdparty service providers who will provide and deliver wireless services. Using the available context information from the wearable device, optimization of service delivery in wireless networks, such as setting up optimal delivery paths between two wearable devices, may be possible without using a third party to do negotiations. In order to fully enable context-awareness, a clear model for how to sense, manage, derive, store, and exchange context information must be defined. This will then provide the platform needed to enable development of context-aware applications that can exploit the possibilities of context-aware computing. The model must take into consideration parameters such as memory usage and power and bandwidth consumption, in order to be efficient on all types of platforms and in all types of networks. It must also be modular enough to survive replacing and upgrading of internal parts.

    Today little research is available about sensing context information, sensor management, APIs towards other applications, and how and how often to present context information to applications. Since context aware computing relies heavily on the ability to obtain and represent context information, sensing strategies greatly affect efficiency and performance. It is therefore of great interest to develop and evaluate models for carrying out these tasks in order to exploit the results of context awareness research. This thesis will identify and design several components of such a model, as well as test and evaluate the design, in order to be able to make conclusions to whether is lives up to the expectations stated.

    In order to make the proper design decisions, a full understanding of the context-awareness research area and the goals and purposes of context-aware computing are required. To understand the entire picture is crucial to find a suitable solution. Therefore, determining an efficient sensor input and management strategy, along with a powerful and flexible API for applications, which are the goals of this thesis, fully qualifies as a significant master thesis assignment.

  • 802.
    Wennström, Christoffer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Kontinuerlig temperaturmätning i bädden på gratevagnar2012Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Luossavaara-Kiirunavaara Aktiebolag (LKAB) är en gruvdriftskoncern med järnmalmsbrytning som huvudsaklig verksamhet. En av produkterna tas fram genom att raffinera järnmalm till pellets vilket är en efterfrågad produkt vid ståltillverkning.

     

    Vid sintring av råkulor till pellets är temperaturen väsentlig för att få så hög oxidation som möjligt av magnetit till hematit och för att få rätt fasthet. För att reglera värmen bör temperaturen mätas bland råkulorna eftersom det är kulornas temperatur som är det viktiga.

                                     

    Projektet går ut på att undersöka möjligheterna att mäta temperatur bland råkulor på gratevagnar som åker genom en pelletsugn med ett permanent mätsystem. Här ställs höga krav på mätsystemet på grund av miljö, portabilitet och drifttid.

    Miljöanalyser gjordes för att ta reda på vilken påfrestning ett mätsystem bör klara av. Förslag om placering av mätutrustning framtogs genom kartläggning av miljön. En värmeundersökning utfördes av vad hög värme har för påverkan på elektroniska komponenter som kan behövas till ett mätsystem.

    Det gjordes även en undersökning över vilka komponenter som kan klara av den värme ett mätsystem kan bli utsatt för. Utifrån detta kunde ett prototypmätsystem konstrueras för att mäta temperaturen där ett mätsystem kan placeras på en gratevagn samt för att skapa möjlighet för mätningar med termoelement i bädd. Mätsystemet skapades med trådlös kommunikation, möjlighet till loggning av data och med möjlighet att ansluta tre termoelement av typ S. Olika typer av trådlös kommunikation utvärderades för att se vad som kan vara mest lämpat med tanke på miljö, räckvidd, strålning och strömförbrukning.

    Strömförsörjning undersöktes för att hitta den mest lämpade strömförsörjningen med längst drifttid och högst funktionalitet.

    En utredning gjordes för att hitta monteringsmöjligheter av ett mätsystem på en gratevagn. Värmeavskärmning och isolering undersöktes för att få ner temperaturen i kapslingen och för elektroniken i ett mätsystem.

    Några olika temperaturgivare granskades för att hitta en som klarar av att mäta temperaturer upp till 1500°C och som fysiskt kan monteras på en gratevagn.

  • 803.
    Westermark, Christian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Mobile Multiplayer Gaming2007Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The last ten years, online multiplayer games have become very popular. During the same time period mobile terminals and cellular networks have undergone a tremendous technical evolution. Therefore it is natural to wonder why we have not seen an online mobile multiplayer gaming revolution yet. The answer to this question is of great value for companies selling mobile systems. This answer is important in order to understand how to fill up today’s empty networks with traffic and what kind of traffic these games will generate.

    This thesis is a continuation of Mattias Åkervik’s thesis. It gives the reader an understanding of what kind of wireless technologies are on the market today and how they perform. Given this performance background, some suitable games were chosen to examine how they perform over a particular cellular network and to determine the perceived gaming quality that a user experience. The thesis also examines the particular packet traffic characteristics generated by these games to gain a better understanding of how to better adapt cellular networks towards gaming.

    Finally the market will be analyzed. Not only how large this potential market is, but to examine if there are some market issues preventing the revolution in network cellular on-line multiplayer games.

  • 804.
    Westin, Ola
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    TCP Performance in Wireless Mobile Multi-hop Ad Hoc Networks2003Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    There are many issues that limit the performance of wireless mobile multi-hop ad hoc networks (MANETs). One of them is that TCP is not well adapted to networks where routes can change or disappear often. In this paper the behaviour of a standard TCP implementation is studied in situations typical for MANETs and compared to the behaviour of a partial implementation of a ATCP, a TCP modification that is intended to increase performance in MANETs.

    Simulations with simple scenarios show that TCP easily creates a full network load which causes send failures and decreased throughput performance. In some cases the partial ATCP implementation increases throughput but more often it causes an increased amount of duplicate retransmissions. In these scenarios it is unlikely that even a complete ATCP implementation would increase throughput performance.

    A few modifications to ATCP and TCP are analysed. Especially a limit of the congestion window size shows a large throughput increase. The results are inconclusive, the simulations are too simple to show if the results are applicable in more complex scenarios. It is not clear if ATCP actually is useful in a MANET.

  • 805.
    Wiberg, Niklas
    KTH, Tidigare Institutioner, Teleinformatik.
    Profile Handling Gateway/Proxy2000Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    When home users surf the Internet (i.e. use the World Wide Web) today, be it by dial-up or by other means, they are virtually anonymous to the sites they visit. Many sites would, according to Iquity Systems’ experience, like to know more about their visitors in order to target the advertisements (e.g. banners) displayed, services offered, etc. It is also likely that site owners are interested in the type of people that visit their site.

    Iquity Systems would like to provide a system that is capable of providing Internet site owners with profile data of the visitors, as well as sharing usage accounts with Iquity’s telephony products. The system should also be supportive of a rating model that lets an access provider running the system charge a user differently for the access, depending on whether the user is presented with targeted advertisements or not. This solution shall be able to be integrated with other parts of the company’s IQ platform. One of these parts is a system for accounting, while another is a user profile handling database.

    This paper discusses the design of such a system.

  • 806.
    Wickbom, Carl
    KTH, Tidigare Institutioner, Teleinformatik.
    SIP and payments: a way of controlling the price2000Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    IP-telephony is said to be the future of telephony, reducing infrastructure investments and enabling new services. IP-telephony solutions exist already in some business buildings as a replacement for PSTN or on the Internet as IP-to-IP telephony. However, before IP-telephony will be a realistic replacement for PSTN two major problems must be solved though; billing and guarantee of the expected QoS. Without the possibility of revenue no company would like to invest money and without QoS no customer will want to replace PSTN with IP-telephony. IP-to-IP telephony exists with best effort traffic for free today, and it will not be possible to charge for it in the future. By introducing value-added features such as PSTN gateway connection, bandwidth reservation and services such as call screening and redirecting, a way of charging the customer is presented in this report.

    The payment solution developed in this thesis is based on SIP and Jalda. The system is built in modules, all with a specific task, hence creating a distributed system, which does not depend on a central part, and following existing standards, avoiding a proprietary solution. It is also general enough to support other types of media than speech, enabling several business ideas including video on demand.

    Security has to be considered seriously when dealing with Internet payments. The solution presented contains both the advantages of SIP with authentication and message encryption, as well as authentication and accounting by Jalda. Authorization is not a problem, as no one will get access to the services without paying, and anyone willing to pay will be granted access. It ends up being a distributed payment solution.

    SIP has the necessary characteristics for constructing billing solutions. As payment seems to be a solvable problem there remains one major difficulty with IP-telephony. Until QoS can be guaranteed or the interference reduced to a minimum, it is not reasonable to imagine IP-telephony replacing PSTN except in well managed intranets where the network can be over dimensioned in such a way as to provide the necessary QoS.

  • 807.
    Wickman, Tomas
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Evaluation of communication protocols between vehicle and server: Evaluation of data transmission overhead by communication protocols2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis project has studied a number of protocols that could be used to communicate between a vehicle and a remote server in the context of Scania’s connected services. While there are many factors that are of interest to Scania (such as response time, transmission speed, and amount of data overhead for each message), this thesis will evaluate each protocol in terms of how much data overhead is introduced and how packet loss affects this overhead. The thesis begins by giving an overview of how a number of alternative protocols work and what they offer with regards to Scania’s needs. Next these protocols are compared based on previous studies and each protocol’s specifications to determine which protocol would be the best choice for realizing Scania’s connected services. Finally, a test framework was set up using a virtual environment to simulate different networking conditions. Each of the candidate protocols were deployed in this environment and setup to send sample data. The behaviour of each protocol during these tests served as the basis for the analysis of all of these protocols. The thesis draws the conclusion that to reduce the data transmission overhead between vehicles and Scania’s servers the most suitable protocol is the UDP based MQTT SN.

  • 808.
    Widfeldt, Fredrik
    KTH, Tidigare Institutioner, Teleinformatik.
    sage of LDAP for managing users and resources in a computer network1997Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Today most organizations keep several separated information directories in which for example computer passwords, e-mail addresses, telephone numbers etc. are stored. A big problem is that much of the information is stored in more than one of the directories and thus it is easy for inconsistencies to develop between the directories. A solution to the problem is to store the information only once - in a central directory server where client applications could access it. LDAP is a protocol used by clients to retrieve information from a directory server.

    This report describes how an LDAP directory may be used to share user data in a computer network. First the concept of distributed directory information is presented. Then LDAP is carefully described and compared with X.500, a larger and more complex service. After that we look at the possibility to implement LDAP when developing own systems. Deployment issues and available LDAP products are discussed. A project demo system is presented and described. The demo system shows how different systems can share user information stored in an LDAP directory and how operating systems may be migrated with the directory. One of the more important parts of the system is a gateway server, forwarding NIS requests to the LDAP directory.

    The goal of the report is to make the reader aware of distributed directory services and what important role they probably will have in the near future.

  • 809.
    Wiklander, Erik
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Mobile Resource Awareness2001Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    New types of cellular networks are appearing on the market, such as GPRS and UMTS. In addition to this, an increasing number of places are being equipped with wireless LAN extensions to the Internet. Simultaneously, new mobile devices are becoming available that can perform complex computations based on events from various input devices and/or information sources. The combination of extended network connectivity and new mobile devices creates new opportunities for network computing.

    This paper presents a scenario where network enabled applications can interact with mobile devices to create a smart space. The ambition is to create a system where mobile devices can be aware of what resources are present at a specific location. The prototype solution in this paper uses an XML-based protocol and a tuple space architecture as a message passing mechanism.

  • 810.
    Wu, Jun
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Signal Collecting Platform and "Handprint" Positioning System2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Mobile computing is an emerging research field in recent years. Although the computation capability of main stream smartphones are several orders of magnitude better than computers twenty years ago, the capacity of battery does not increase at same speed. To save energy, some recent work tries to schedule network traffic according to signal strength variations. To achieve this goal, a database that is used for storing signal strength distribution is essential.We first design and implement a platform to collect cellular network information, including Cell-ID and signal strength information. The platform is designed as a distributed system that supports collecting signal strength data by using crowdsourcing approach.We then deploy the platform and collect signal strength information in Otaniemi area (Finland). After analysing the collected data, we observe several interesting phenomenons. (1) the density of base stations is out of expectation; (2) cells is becoming smaller; (3) in most places a device may connect to different base stations. Based on these observations, we design a new energy-efficient positioning system called “handprint”, which utilises signal strength information from neighbouring smartphones to assist positioning. Compared with Google Geolocation API and other existing work, our “handprint” system can improve positioning accuracy by more than 20%.

  • 811.
    Wu, Xiao
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    SIP on an Overlay Network2009Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    With the development of mobile (specifically: wide area cellular telephony) technology, users’ requirements have changed from the basic voice service based on circuit switch technology to a desire for high speed packet based data transmission services. Voice over IP (VoIP), a packet based service, is gaining increasing attention due to its high performance and low cost. However, VoIP does not work well in every situation. Today Network address translation (NAT) traversal has become the main obstruction for future VoIP deployment.

    In this thesis we analyze and compare the existing NAT traversal solutions. Following this, we introduce a VoIP over IPSec (VOIPSec) solution (i.e., a VoIP over IPSec virtual private network (VPN) scheme) and an extended VOIPSec solution mechanism. These two solutions were tested and compared to measure their performance in comparison to a version of the same Session Initiation Protocol (SIP) user agent running without IPSec.

    In the proposed VOIPSec solution, the IPSec VPN tunnel connects each of the SIP clients to a SIP server, thus making all of the potential SIP participants reachable, i.e., solving the NAT traversal problem. All SIP signaling and media traffic for VoIP calls are transmitted through this prior established tunnel. This VPN tunnel provides the desired universal means for VoIP traffic to traverse NAT equipment. Additionally, the IPSec VPN also guarantees the security of VoIP calls at the IP level.

    In order to improve the security level of media streams for the VOIPSec solution, we deployed and evaluated an extended VOIPSec solution which provides end-to-end protection of the real time media traffic. In this extended VOIPSec solution, we used SRTP instead of RTP to carry the media content. This extended method was shown to provide all of the advantages of VOIPSec and SRTP without any additional delay for the media traffic (as compared to the VoIPSec solution).

    Note that the solution proposed in this thesis may be of limited practical importance in the future as more NATs become VoIP capable; but the solution is currently essential for facilitating the increasing deployment of VoIP systems in practice. For VoIP calls that do not need end-to-end security, we recommend the use of the VOIPSec solution as a means to solve the NAT traversal problem and to protect traffic at the IP level. When application to application security is not needed we prefer the VOIPSec solution to the extended VOIPSec solution for the following reasons: (1) our test results show that the time for call setup for the extended VOIPSec solution is twice time the time needed for the VOIPSec solution and the extended VOIPSec solution requires the use of user agents that support SRTP. While, the VOIPSec solution does not require a special user agent and all VoIP clients in the market are compatible with this solution. However, when more SIP user agents add support for SRTP, the extended VOIPSec solution will be applicable for users of these SIP user agents.

  • 812.
    Wu, Yongliang
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Aggregating product reviews for the Chinese market2009Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    As of December 2007, the number of Internet users in China had increased to 210 million people. The annual growth rate reached 53.3 percent in 2008, with the average number of Internet users increasing every day by 200,000 people. Currently, China's Internet population is slightly lower than the 215 million internet users in the United States. [1]

    Despite the rapid growth of the Chinese economy in the global Internet market, China’s e-commerce is not following the traditional pattern of commerce, but instead has developed based on user demand. This growth has extended into every area of the Internet.

    In the west, expert product reviews have been shown to be an important element in a user’s purchase decision. The higher the quality of product reviews that customers received, the more products they buy from on-line shops. As the number of products and options increase, Chinese customers need impersonal, impartial, and detailed products reviews. This thesis focuses on on-line product reviews and how they affect Chinese customer’s purchase decisions.

    E-commerce is a complex system. As a typical model of e-commerce, we examine a Business to Consumer (B2C) on-line retail site and consider a number of factors; including some seemingly subtitle factors that may influence a customer’s eventually decision to shop on website. Specifically this thesis project will examine aggregated product reviews from different on-line sources by analyzing some existing western companies. Following this the thesis demonstrates how to aggregate product reviews for an e-business website.

    During this thesis project we found that existing data mining techniques made it straight forward to collect reviews. These reviews were stored in a database and web applications can query this database to provide a user with a set of relevant product reviews. One of the important issues, just as with search engines is providing the relevant product reviews and determining what order they should be presented in. In our work we selected the reviews based upon matching the product (although in some cases there are ambiguities concerning if two products are actually identical or not) and ordering the matching reviews by date - with the most recent reviews present first.

    Some of the open questions that remain for the future are: (1) improving the matching - to avoid the ambiguity concerning if the reviews are about the same product or not and (2) determining if the availability of product reviews actually affect a Chinese user's decision to purchase a product.

  • 813.
    Xie, Tian
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori.
    Knowledge discovery and machinelearning for capacity optimizationof Automatic Milking RotarySystem2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Dairy farming as one part of agriculture has thousands of year’s history. The increasingdemands of dairy products and the rapid development of technology bring dairyfarming tremendous changes. Started by first hand milking, dairy farming goes throughvacuum bucket milking, pipeline milking, and now parlors milking. The automatic andtechnical milking system provided farmer with high-efficiency milking, effective herdmanagement and above all booming income.DeLaval Automatic Milking Rotary (AMRTM) is the world’s leading automatic milkingrotary system. It presents an ultimate combination of technology and machinerywhich brings dairy farming with significant benefits. AMRTM technical milking capacityis 90 cows per hour. However, constrained by farm management, cow’s condition andsystem configuration, the actual capacity is lower than technical value. In this thesis, anoptimization system is designed to analyze and improve AMRTM performance. The researchis focusing on cow behavior and AMRTM robot timeout. Through applying knowledgediscover from database (KDD), building machine learning cow behavior predictionsystem and developing modeling methods for system simulation, the optimizing solutionsare proposed and validated.

  • 814.
    Xing, Hanwen
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    Liu, Xin
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för fysik och elektroteknik (IFE).
    A Lithium-ion Battery Charger2015Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

       Nowadays personal small electronic devices like cellphones are more and more popular, but the various batteries in need of charging become a problem. This thesis aims to explain a Lithium-ion charger which can control the current and voltage so that it can charge most kinds of popular batteries. More specifically, Li-ion battery charging is presented. The charging circuit design, simulation and the measurements will also be included.

  • 815.
    Xiong, Xuelin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    SCTP and Diameter Parameters for High Availability in LTE Roaming2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Today mobile network operators utilize IP Packet exchange (IPX) carriers to interconnect their networks with other operators. Mobile network operators are free to choose one IPX carrier for their data traffic and another for their control traffic. This thesis examines the case of control traffic, specifically Stream Control Transmission Protocol (SCTP) carrying Diameter protocol traffic arising from users roaming from their home Long Term Evolution (LTE) network to another operator’s LTE network.

    The thesis project aims to identify a set of SCTP parameter configurations that can provide improved application/service level availability between two Diameter nodes in different network connectivity environments, specifically for IPX carriers who are Diameter service providers. These service providers provide Diameter connectivity for their customers who are mobile network operators. These mobile network operators in turn provide LTE roaming services to their customers.

    Unfortunately, applying the ‘One size fits all’ configuration recommendations given in the SCTP documentation is unsuitable for different network environments. In addition, the amount of Diameter signaling traffic is growing at a very rapid rate. Therefore, it is valuable to identify suitable parameter selection criteria for Diameter service providers to ensure 100% Diameter connectivity reliability for their customers. In this thesis project, author investigated how tuning SCTP parameter values affect Diameter message transmission in terms of Round Trip Delay and identified its determining parameters for packet loss recovery performance. Both IPX carriers and mobile network operators may use these values as reference when attempting to ensure high availability of Diameter transmissions under reliable, semi reliable, and unreliable network transport conditions.

  • 816.
    Xiong, Ziyi
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Socio-economic Impact of Fiber to the Home in Sweden2013Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Fiber-to-the-Home (FTTH) has been talked about since the introduction of fiberin the 1970s. It is nowadays shaping up to be the foundation of our newdigital society, bringing economic prosperity and a multitude of business,social, and entertainment opportunities to its users. The increased consumerdemand for high-speed network accessibility is being taken more and moreseriously and a fiber-based network is able to cope with these growing demandsdue to its wide bandwidth and reliability. Today there is a practical need forquantitative analysis regarding the socio-economic impacts of fiber-basedaccess networks. This analysis could be used as an indicator/reference for allthe stakeholder entities as they consider future investments anddevelopments. Sweden is a suitable target country for this analysis since ithas adopted fiber for some years and the benefits that FTTH has brought seemto already be tangible.

    The primary value of this thesis lies ininvestigation of its quantified evidence of the socio-economic impacts of FTTHdeployment in Sweden. This has been achieved based on data from the SwedishPost and Telecommunications Authority (PTS), Statistics Sweden (SCB), previousrelated studies, and information collected on-line from operators involved inthe fiber market, along with empirical analysis based on multivariateregression models.

    The results of the study show that fiber penetrationhas had a significant impact on the population’s evolution, specially the netamount of migration into a municipality, which indicates the attractiveness ofmunicipalities per se. It is therefore reasonable to suggest that localgovernment and local authorities take fiber deployment into consideration, ifthey want to attract people to stay for further local development. The studyalso analyzed the competition in fiber-based open networks and the prices ofsubscribing for 10/10 Mbps symmetrical Internet Service. Study findingsrevealed that networks with multiple competing service providers have a widerrange of services and a lower price: the more ISPs competing in a fibernetwork, the lower consumer prices. Specifically, for each new serviceprovider present in the network, there will be 5 SEK per month decrease of theaverage price of the Internet services, and an approximately 7 SEK per monthreduction in the lowest price.

    Nevertheless, a number of socio-economicimpacts remain unquantifiable as of the current time and due to the limitedavailable data. It is recommended to incorporate more socio-economic effectsin future research in order to draw a more complete picture for all theinterested sectors, and to supplement the data with recent figures for 2012and 2013.

  • 817.
    Yang, Ching-Hsiang
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem.
    Screen Content Coding in HEVC: Mixed Raster Content with Matching Pursuit2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
  • 818.
    Yang, Dekun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Investigation of a new integration test environment: Facilitating offline debugging of Hardware-in-the-Loop2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Advanced automatic testing is very important in development and research within the vehicle industry. Hardware-in-the-loop (HIL) systems give the ability to validate Electronic Control Units (ECUs) based on software simulation without gathering all of the physical hardware. This enables testing by providing inputs and examining the corresponding outputs of the ECUs in a simpler and safer way than in traditional physical testing. HIL offers the advantage that we can verify and validate the functions of ECUs prior to full-scale hardware production.

    On the contrary, because HIL systems are normally released as general-purpose test beds, it takes time to embed them into the current system. Additionally, the question of how to fill the gap between the HIL and the test environment is even more critical when the test bed is expected to be used for a long period of time without modifications. Furthermore, HIL systems are precious. It is not practical and will be considered as a waste of resource if it is used exclusively by testers. Scania’s RESI group uses Client-Server architecture to make it more flexible. The HIL system is hosted at server side while the testers operate it at client side. This architecture enables different implementations of client and server as long as a same protocol is applied, but this still does not solve the problem that the HIL is not always accessible when the testers want to debug their scripts. The testers want to find a solution to achieve this goal offline (without servers).

    To solve the problem, we first investigated which programming languages are used in the industry. Without doubt, there is no dominant language that ideally suits all situations, so secondly, we developed a new test environment. The new environment including “Dummy Mode” and “Mat Mode” is able to provide script validation service on basic and logic levels without servers. The result shows the Dummy mode is able to reach a higher detection rate (99.3%) on simple errors comparing to the current environment (81.3%). By reproducing and reusing the result of HIL system, Mat mode is able to identify logic errors and provide better assistance when the logic errors are found. In general, the proposed environment is able to show a better way of using HIL which makes the whole system more efficient and productive.

  • 819.
    Yang, Xi
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    The Use of One-Time Password and RADIUS Authentication in a GSS-API Architecture2006Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The Generic Security Service Application Program Interface (GSS-API) is an architecture that facilitates applications using distributed security services in a mechanism-independent fashion. GSS-API is supported by various underlying mechanisms and technologies such as Kerberos version 5 and public-key technologies. However, no one-time password based GSS-API mechanism existed.

    This thesis focuses on an investigation using one-time passwords together with RADIUS authentication as a protection facility for a GSS-API mechanism. This thesis presents a security architecture using one-time passwords to establish a GSS-API security context between two communicating peers.

    The proposed one-time password based GSS-API mechanism could be used to enhance the security of user authentication. Moreover, the mechanism can greatly facilitate static-password based system’s transition to stronger authentication.

  • 820.
    Yanggratoke, Rerngvit
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikation: Infrastruktur och tjänster, Telekommunikationssystem, TSLab.
    GPU Network Processing2010Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Networking technology is connecting more and more people around the world. It has become an essential part of our daily life. For this connectivity to be seamless, networks need to be fast. Nonetheless, rapid growth in network traffic and variety of communication protocols overwhelms the Central Processing Units (CPUs) processing packets in the networks. Existing solutions to this problem such as ASIC, FPGA, NPU, and TOE are not cost effective and easy to manage because they require special hardware and custom configurations.

    This thesis approaches the problem differently by offloading the network processing to off-the-shelf Graphic Processing Units (GPUs). The thesis's primary goal is to find out how the GPUs should be used for the offloading. The thesis follows the case study approach and the selected case studies are layer 2 Bloom filter forwarding and flow lookup in Openflow switch. Implementation alternatives and evaluation methodology are proposed for both of the case studies. Then, the prototype implementation for comparing between traditional CPU-only and GPU-offloading approach is developed and evaluated.

    The primary findings from this work are criteria of network processing functions suitable for GPU offloading and tradeoffs involved. The criteria are no inter-packet dependency, similar processing flows for all packets, and within-packet parallel processing opportunity. This offloading trades higher latency and memory consumption for higher throughput.

  • 821.
    Yi, Xiaokun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Adaptive Wireless Multimedia Services2006Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Context-awareness is a hot topic in mobile computing currently. A lot of importance is being attached to facilitating the user of various mobile computing devices to provide services that are more “user-centric”. One aspect of context-awareness is to perceive variations in available resources, and to make decisions based on the feedback to enable applications to automatically adapt to the current environment.

    For Voice over IP (VoIP) software phones (softphones), variations in network performance lead to fluctuations in the quality of the communication. Therefore, by making these softphones more adaptive to the network environment will, to some extent, mask such fluctuations. Dynamic voice and video adaptation derives from the fact that different coder-decoders (CODEC) have different characteristics, even the same CODECs with a different configuration can behave quite differently, in terms of bandwidth consumption, packet size, etc.

    Minisip is a VoIP client application which was implemented on and targeted for a Linux platform. One of my tasks was to port Minisip to Microsoft’s Windows Mobile operating system, running on an HP IPAQ Pocket PC H5550. Such handheld computer enables the user to communication while they are moving about, thus increasing the probability that the characteristics of the network connection will change. Building upon this port, the next task was to add dynamic voice and video CODEC adaptation. Dynamic voice and video CODEC adaptation on Minisip poses several challenges, for example, in what way can the network performance be determined and what adaptation strategy can achieve high call quality while making efficient utilization of available network resources.

    In order to make the proper design choices, several estimation models will be discussed, these are used to determine an efficient, un-intrusive, and light weight means of dynamic CODEC selection within Minisip. This thesis only implemented audio CODEC adaptation of Minisip, and the evaluation of the resulting prototype shows that such dynamic adaptation is both feasible and practical; further more, video CODEC adaptation would be a more significant extension to this work in the future.

  • 822.
    Yunda Lozano, Daniel
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Improving vertical handover performance for RTP streams containing voice: Using network parameters to predict future network conditions in order to make a vertical handover decision2007Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Wireless local area networks WLAN and Voice over IP technologies enable local low cost wireless telephony, while cellular networks offer wide-area coverage. The use of dual mode WLAN-cellular terminals should allow cost savings by automatically switching from GSM to WLAN networks whenever it is feasible. However, in order to allow user mobility during a call, a handover procedure for transferring a call between the WLAN interface and the cellular network should be defined. The decision algorithm that triggers such a handover is critical to maintain voice quality and uninterrupted communication. Information or measurements collected from the network may be used to anticipate when the connection will degrade to such a point that a handover is desirable in order to allow a sufficient time span for the handover’s successful execution. It is the delay in detecting when to make a handover and the time to execute it that motivates the need for a prediction.

    The goal of this thesis is therefore to present a method to predict when a handover should be made based upon network conditions. We selected a number of WLAN and VoIP software tools and adapted them to perform the measurements. These tools allowed us to measure parameters of the WLAN’s physical and link layers. Packet losses and jitter measurements were used as well. We have assumed that there is ubiquitous cellular coverage so that we only have to be concerned with upward handovers (i.e, from the WLAN to the cellular network and not the reverse). Finally we have designed and evaluated a mechanism that triggers the handover based in these measurements.

  • 823.
    Zafar, Bilal
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Network Coding Employing Product Coding at Relay Stations2009Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Network coding is a useful tool to increase the multicast capacity of networks. The traditional approach to network coding involving XOR operation has several limitations such as low robustness and can support only two users/packets at a time,per relay, in the mixing process to achieve optimal error performance. We propose the employment of product coding at the relay station instead of xor and investigate such a system where we use the relay to generate product codes by combining packets from different users.Our scheme uses relays to transmit only the redundancy of the product code instead of the whole product code.We seek to employ product coding can be able to support more than two users/packets per relay per slot,while maintaining a good error performance. Our scheme can accomodate as many users per relay as the costituent block code allows, thus reducing the number of relays required in the network. Product codes also offer increased robustness and flexibility as well as several other advantages, such as proper structure for burst error correction without extra interleaving. We compare the performance of such a scheme to the conventional xor scheme and see that our scheme not only reduces the number of relays required but gives improved error performance as well as. Another encouraging result is that our scheme starts to significantly outperform the conventional one by introducing a gain at the relay.

  • 824.
    Zahidi, Salman
    Linköpings universitet, Institutionen för systemteknik, Informationskodning.
    Biometrics - Evaluation of Current Situation2011Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Information security has always been a topic of concern in the world as an emphasis on new techniques to secure the identity of a legitimate user is regarded as top priority. To counter such an issue, we have a traditional way of authentication factors “what you have” and “what you know” in the form of smart cards or passwords respectively. But biometrics is based on the factor “who are you” by analyzing human physical or behavioral characteristics. Biometrics has always been an efficient way of authorization and is now considered as a $1500 million industry where fingerprints dominate the biometrics while iris is quickly emerging as the most desirable form of biometric technique.The main goal of this thesis is to compare and evaluate different biometrics techniques in terms of their purpose, recognition mechanism, market value and their application areas. Since there are no defined evaluating criteria, my method of evaluation was based on a literature survey from internet, books, IEEE papers and technical surveys. Chapter 3 is focused on different biometrics techniques where I discuss them briefly but in chapter 4, I go deeper into Iris, fingerprints, facial techniques which are prominent in biometrics world. Lastly, I had a general assessment of the biometrics, their future growth and suggested specific techniques for different environment like access controls, e-commerce, national ids, and surveillance.

  • 825.
    Zandieh, Behdis
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Indoor Wireless Local Area Network (WLAN): Measurement and Modeling from a user perspective2007Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    If we had detailed wireless local area network (WLAN) coverage maps, both staff and equipment could be used more efficiently, for example, less time would be spent searching for connectivity. In addition, system administrators could understand their WLAN's utilization better, thus enabling better planning for where to install new access points, where to remove access points, where to change the type of antenna, etc. This thesis concerns creating detailed indoor coverage models by using measured network performance - in order to enable both users and administrators to visualize the network coverage. Today a user can only easily know about the access points that they currently hear – in the location where they currently are. Giving the users and administrators access to a model of the entire campus coverage will allow them to understand not only the _local_ coverage, but the patterns of coverage (or lack there of). However, no efficient modeling techniques are currently available for those deploying and operating indoor WLANs.

    The thesis begins with some general background information and then examines a number of WLAN survey tools; in terms of both their performance and cost. Following this a number of related projects are presented. This background provides the motivation for why a new tool is needed and what functions such a tool should have.

    Next a site survey of the KTH campus in Kista was conducted using a newly developed survey application. This application was developed to better meet the requirements derived from the missing functionality of existing tools. In addition, developing this application gave the author an opportunity to learn a new objectoriented programming language, i.e. C# and the .NET environment. Learning to use this new environment was essential to building both an easy to use application and collecting the data from the system - the later was often not straight-forward.

    ne of the key issues after data collection is how to present the collected data to the user and how this varies depending upon the user’s interests and task. An initial representation of the experimental data is presented as a manually painted coverage map overlayed onto a map. Next the thesis examines how to integrate the experimental data using Google’s SketchUp in order to build a 3D model of the WLAN coverage on this campus.

    Future work related to this thesis should focus on how to automate the collection of data and how to automate the presentation of the resulting experimental data.

  • 826.
    Zapolskas, Vytautas
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Securing Cloud Storage Service2012Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Cloud computing brought flexibility, scalability, and capital cost savings to the IT industry. As more companies turn to cloud solutions, securing cloud based services becomes increasingly important, because for many organizations, the final barrier to adopting cloud computing is whether it is sufficiently secure.

    More users rely on cloud storage as it is mainly because cloud storage is available to be used by multiple devices (e.g. smart phones, tablets, notebooks, etc.) at the same time. These services often offer adequate protection to user's private data. However, there were cases where user's private data was accessible to other users, since this data is stored in a multi-tenant environment. These incidents reduce the trust of cloud storage service providers, hence there is a need to securely migrate data from one cloud storage provider to another.

    This thesis proposes a design of a service for providing Security as a Service for cloud brokers in a federated cloud. This scheme allows customers to securely migrate from one provider to another. To enable the design of this scheme, possible security and privacy risks of a cloud storage service were analysed and identified. Moreover, in order to successfully protect private data, data protection requirements (for data retention, sanitization, and processing) were analysed. The proposed service scheme utilizes various encryption techniques and also includes identity and key management mechanisms, such as "federated identity management".

    While our proposed design meets most of the defined security and privacy requirements, it is still unknown how to properly handle data sanitization, to meet data protection requirements, and provide users data recovery capabilities (backups, versioning, etc.).

  • 827.
    Zeeck, Simon
    KTH, Tidigare Institutioner, Teleinformatik.
    Cellular Interworking: Handover between WATM and GSM1998Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    In a wireless environment, it is interesting to roam between different wireless systems, especially if the coverage of one or more of these systems are limited to a certain restricted area, or if there is a cost difference. My work has focused on the support of continuous handover in such a case. The work has focused on Wireless ATM and GSM as bearers for data traffic. The mobile terminal is considered to connect to the GSM or Wireless ATM network. Internet (IP networking) is considered to be the aim of the connection.

    UMTS will probably be the base for new cellular systems. The UMTS core network will most likely be based on ATM. This is what is suggested in the standardization and has support from both Ericsson and Nokia. The WATM is an interesting option for "high speed" wireless network interface that can be connected to UMTS.

    The solution has tried the approch of combining layer 2 tunneling with layer 3 signalling and investigated another solution than network layer mobility.The reasons to investigate this has been:

    • Layer 2 tunneling is a well-know and proven concept in cellular networks
    • The layer 2 connection can be transparently changed while being mobile.
    • Both QoS and traffic parameters in layer2 (e.g., ATM) can be used
    • The freedom and power of IP on layer 3 for signaling (and for data, of course)
  • 828.
    Zhang, Congcong
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för informations- och kommunikationssystem.
    A Distributed Range Query Framework for Internet of Things2014Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    With the rapid development of information technology, applications referring to the Internet of things are booming. Applications that gather information from sensors and affect the context environment with actuators can provide customized and intelligent behaviour to users. These applications have become widely used nowadays in daily life and have initiated the multi-dimensional range query demand referring to the Internet of things. As the data information is fully distributed and the devices like sensors, mobile phones, etc., has limited resources and finite energy, supporting efficient range query is a tough challenge. In this paper, we have proposed a distributed range query framework for Internet of things. In order to save energy costs and reduce the network traffic, we suggest a reporting data range mechanism in the sensing peers, which choose to report a data range and report again only when the peer senses an abnormal data instead of the common moving data method. In addition, we selected some strong peers to be used as the super peers to create a data index by collecting the reporting data range, which will be used for performing range queries. The study has shown that our proposal framework could reduce resource costs in the less strong peers like sensors and mobile phones, and reduce network traffic among all the peers within the network, as well as support a range query function. According the evaluation results, the reporting data range method could greatly reduce the data migration times and save energy costs, and the data index could significantly reduce accessing unnecessary peers and diminish the network traffic.

  • 829.
    Zhang, Hao
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för informations- och kommunikationssystem.
    A Peer to Peer Security Protocol for the Internet of Things: Secure Communication for the SensibleThings Platform2014Independent thesis Advanced level (degree of Master (One Year)), 20 poäng / 30 hpOppgave
    Abstract [en]

    With the rapid development of the Internet connected technologies and applications, people are keen on embracing the convenience and practi-­‐‑ calities they brings. As all kinds of technologies improve, the Internet of Things matures and is able to provide more advanced services to people, which connects a variety of devices, systems and applications beyond traditional machine-­‐‑to-­‐‑machine. However, it covers a variety of devices, protocols and applications, which makes it much more complex than a normal network. Nevertheless, equipped with appropriate security solutions, the Internet of Things is promising to bring us more conven-­‐‑ iences and be widely applied in our daily life. And like the main appli-­‐‑ cation areas, wireless sensor networks with a frequent but short com-­‐‑ munication character, it requires an efficient and flexible protocol to protect the information. To protect the traffic of the Internet of Things is the focal point of this research work. Although many protocols for the Internet have been put forward, it is still not enough to meet the increas-­‐‑ ingly complex requirements from applications. Many of them are not efficient enough to adapt the device diversity and timely communica-­‐‑ tion environment. This research work is trying to address this problem, by proposing a peer-­‐‑to-­‐‑peer security protocol to satisfy this varied environment. Secure communication is implemented on an open sourced platform for the Internet of Things. The philosophy of the platform it implemented on is also inherited to this protocol and the implementation. It avoids unnecessary handshakes between entities, which makes it more efficient in a wireless sensor network. Modulariza-­‐‑ tion and unit test are adapted in implementation to enhance the robust of the system. Its dynamic security level adjustment feature satisfies the realistic demand on one platform this protocol is implemented on. Finally, with a comparison test and an analysis using the BAN logic, the result shows that the proposed protocol is efficient to meet the specific goals and applicable for the platform. 

  • 830.
    Zhang, Hengchong
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Non-binary Authentication: Supplicant2009Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    There are a number of authentication methods for wireless local area networks. The IEEE 802.1x standard is one such method. This standard specifies a port-based access control protocol. There are three entities involved: a supplicant (a device that wishes to have network access and perhaps other services), an Access Point (AP) or other port to which access is to be controlled, and an Authentication Server (AS). The goal of this project was to design, implement, and evaluate a prototype of a non-binary alternative to IEEE 802.1x authentication. This report focuses on the supplicant. Specifically it describes the design, implementation, and evaluation of a supplicant program to test and stress the authenticator, in order to evaluate a non-binary authentication process.

    Following, a brief introduction is given to the problem that is to be solved, a number of existing IEEE 802.1x supplicants are described and compared. Following this, a number of potential non-binary authentication processes are analyzed. The ability of a supplicant to send and receive packets before and after authentication is also examined. Based upon our implementation and evaluation of a supplicant and an emulation of the non-binary authentication process, we conclude that non-binary authentication is both feasible and valuable. Furthermore, the thesis evaluates why and how non-binary authentication is valuable from the viewpoint of a supplicant. Additional future work is suggested at the end of this thesis.

  • 831.
    Zhang, Shasha
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Device aggregation with data networking: Implementing a Personal Area Network2008Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Technology is advancing rapidly and intelligent devices are becoming affordable and wireless infrastructure is becoming pervasive. Personal information technology appliances have become part of our life, via cellular phones, PDAs, Bluetooth headsets, handheld keyboards, GPS, and digital cameras. In the future, new intelligent devices will be invented as technology evolves. However, because multiple devices provide similar (but different) functionality it is complex for the average user to choose a single device. Moreover, today it is hard to configure, administer, and use several different appliances together. In order to be utilized in an effective manner and in an accessible way, personal devices should be aggregated, i.e., connected together via a local area network so that they can appear to the user as if they were a single device.

    This paper introduces a connection model based on device aggregation to realize shared state, the behavior of a shared appliance, and with the superset of the individual device functionality. Such an aggregated logical device might even exhibit functions which a user would have a very hard time realizing by manually combining devices. This will facilitate the user’s control over their appliances (build of different devices), but acting as one device.

    The project was a joint effort with David Sabaté Mogica. We developed such a system based on Dynamic Host Client protocol (DHCP) and Service Location Protocol (SLP) for service discovery and Virtual Network Computing (VNC) for remote desktop control. The system builds on a laboratory network environment. This thesis concerns the implementation and evaluation of service discovery. The Remote desktop control was researched and implemented separately and will be reported separately. Service discovery between two computers has been implemented using a custom program developed for a PDA. However, at present the PDA only sends a DA request packet with DHCP. However, service discovery has been successfully tested between two computers. This provided an important base for the programming on PDA and the future development of a similar program for a cellular phone.

  • 832.
    Zhang, Yan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Wireless sensor network for volcano monitoring2005Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The monitoring of volcanoes for risk assessment has deployed single sensors for years. This kind of system requires manual supervision to monitor each sensor, which makes the monitoring work not flexible and efficient enough to adapt to variable volcano environments. With the development of wireless sensor networks, the accuracy and coverage of volcano observations can be improved by deploying networked sensors. This paper proposes a wireless sensor network prototype for volcano remote monitoring, which was built and tested in a field campaign in volcano Etna, Italy in September of 2004.Hardware design of sensors, in-depth sensor network design and software module architecture will be introduced in this paper. The experience gained from the practical work in volcano Etna will be used in an upcoming volcano monitoring project.

  • 833.
    Zhang, Yuanhui
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Evaluating a publish/subscribe proxy for HTTP2013Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    With the increasingly high speed of the Internet and its wide spread usage, the current Internet architecture exhibits some problems. The publish/subscribe paradigm has been developed to support one of the most common patterns of communication. It makes “information” the center of communication and removes the “location-identity split” (i.e., that objects are at specific locations to which you must communicate with to access the object). In this thesis project a publish/subscribe network is built and then used in the design, implementation, and evaluation of a publish/subscribe proxy for today’s HTTP based communication. By using this proxy users are able to use their existing web browser to send both HTTP requests and Publish/Subscribe Internet Routing Paradigm (PSIRP) requests. A publish/subscribe overlay is responsible for maintaining PSIRP contents. The proxy enables web browser clients to benefit from the publish/subscribe network, without requiring them to change their behavior or even be aware of the fact that the content that they want to access is being provided via the publish/subscribe overlay. The use of the overlay enables a user’s request to be satisfied by any copy of the content, potentially decreasing latency, reducing backbone network traffic, and reducing the load on the original content server. One of the aims of this thesis is to make more PSIRP content available, this is done by introducing a proxy who handles both HTTP and PSIRP requests, but having received content as a result of an HTTP response it publishes this data as PSIRP accessible content. The purpose is to foster the introduction and spread of content based access.

  • 834.
    Zhao, Zhengjian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Mediating updates using a web based service2007Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The European Commission had approved the Registration, Evaluation and Authorization of Chemicals (REACH) regulations in the year 2006, and will begin to implement it form 1 June 2007. This regulation greatly increases safety of protection for the users of chemicals, but it also brought a problem for the manufactures as well as downstream users. That is they have to generate and distribute much more Material Safety Data Sheets (MSDS) then before. This work is difficult for most companies since this job usually was done manually. The new regulation requires a much more efficient method to generate and distribute them.

    This thesis project addresses the problem of automatically distributing MSDS and the corresponding metadata. It presents the underlying technology selected for this project. It gives a brief introduction of this project, the underlying technologies used, along with the methods used to deliver relevant and up to date materials safety information.

    At last an HTTP web application approach was selected to solve the problem, the resulting application can efficiently notify a downstream user of the newly updated MSDS and transport the corresponding file and metadata. It is truly data driven, therefore the downstream user does not need to check for updates everyday, instead will be notified when there is an available update.

  • 835.
    Zhou, Jia
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Adding bandwidth specification to a AAA Sever2008Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Authentication, authorization, and accounting (AAA) are key elements in network security. In many networks, clients can use resources only after they have been authenticated by an authentication server and authorized to use these resources. In some cases the server will also maintain accounting records in order for an operator (a provider of resources) to charge the account/subscriber for using the service. There are four main AAA protocols being used today. Of these RADIUS is the mostly widely used.

    This thesis starts with an introduction to AAA protocols, and then goes in the details of RADIUS. In order to perform a practical evaluation of how the AAA could be improved, FreeRADIUS was selected as the base code for this project; because this implementation is one of the most widely used RADIUS servers. A proposal for how to improve AAA performance is introduced and the implementation steps needed to realize these improvements are shown. Additionally, some experiments have been conducted to show both the correct functioning of the resulting implementation and to examine if there is a performance improvement. Following this some conclusions are drawn based upon a comparison with a traditional AAA server.

    A key element of the change in AAA which is proposed is the use of a non-binary IEEE 802.1x process. This new non-binary solution introduces a new type of AAA server and requires the re-thinking of a number of traditional AAA design decisions. It is expected that this change will have a significant impact, but will require some time for exposure, implementation by others, and a more extensive evaluation that was possible during the period of this thesis project.

    One of the most important conclusions drawn during this thesis is the difficulty of making a change in authentication and authorization, because of the large amount of interaction between both the various protocols and the standards which have been developed for these protocols. Thus one of the difficult aspects of the task is how to introduce a change in a protocol while maintaining backward compatibility for others who have not adopted this change -- without requiring the addition of a protocol version field.

    A second important conclusion is that doing this implementation in three separate parts with different students being responsible for the different parts revealed just how complex the interaction of protocol design decisions are. While a working version of the entire set of changes proved to be impossible, it was observed that the different parts could be decoupled more than initially expected.

  • 836.
    Zhu, Wanning
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Multipoint Relay flooding: Network coding improvements2009Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Network coding is a new research area with potential to reduce network resources. With network coding, intermediate nodes forward packets that are linear combinations of previously received packets.

    The type of networks we consider are vehicle mounted mobile tactical radio networks. Tactical communication may be required in areas where pre-deployed base stations are unavailable. Mobile ad hoc networks satisfy this requirement. Due to low antenna heights, network resources are scarce inmobile networks without base stations. Broadcast traffic, which disseminates information network-wide, is very important in tactical mobile networks. Multipoint relay flooding is a well-known technique for efficient distribution of broadcast traffic. It is therefore interesting to evaluate how much network coding can reduce the number of transmissions in a mobile ad hoc network. In this thesis we show that it is possible to further reduce the number of transmissions for Multipoints Relay flooding by using network coding. However, this improvement is largely theoretical - there has been no effort to evaluate this approach in practice.

  • 837.
    Zografos, Alexandros
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Wireless Sensor-based Agricultural Monitoring System2014Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Today energy resources are becoming scarcer and therefore more valuable. In conjunction with the population growth over last century, the need for finding new, more efficient, and sustainable methods of agricultural cultivation and food production has become more critical. To facilitate this process, we are designing, building, and evaluating a system for precision agriculture which provides farmers with useful data about the soil, the water supply, and the general condition of their fields in a user friendly, easily accessible manner. Our system aims to make cultivation and irrigation more efficient as the farmer is able to make better informed decisions and thus save time and resources.

    The diversity of location and climatic effects upon agricultural cultivation, along with other environmental parameters over time makes the farmer’s decision-making process more complicated and requires additional empirical knowledge. Applying wireless sensor networks for monitoring environmental parameters and combining this information with a user-customized web service may enable farmers to exploit their knowledge in an efficient way in order to extract the best results from their agricultural cultivation. The system can scale based on each farmer’s demands and the resulting ensemble of collected information may represent a valuable resource for future use, in addition to its use for real-time decision making. The design of the precision agriculture system contains a prototype solution regarding the sensor platform and a customizable service that can be utilized in different ways and by several entities.

  • 838.
    Åhman, Stefan
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Wallstersson, Marcus
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    EVH2 protocol: Performance analysis and Wireshark dissector development2012Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    EVH2 is a proprietary application layer protocol developed by Aptilo Networks and used in their software product. Currently the only way to inspect EVH2 traffic is by using their own application. This application inspects no traffic other than EVH2. Since Aptilo continuously develops this protocol it is important to see how changes in the protocol affect its performance. This thesis examines possible ways to facilitate the use and development of the protocol.

    To analyse EVH2 network traffic along with traffic from other protocols another approach is needed. Wireshark is an application capable of inspecting traffic of multiple protocols simultaneously and uses dissectors to decode each packet. This thesis describes the development and evaluation of a Wireshark plugin dissector for inspection of EVH2 traffic.

    Performance tests of EVH2 will provide feedback about protocol changes. This thesis creates a platform for performance evaluation by introducing a test suite for performance testing. A performance evaluation of EVH2 was conducted using the developed test suit.

  • 839.
    Åkervik, Mattias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Network Gaming: Performance and Traffic Modeling2006Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    There are several different types of games that are played in multiplayer mode over networks. The type of network games that, from a network’s perspective, are the most demanding is real-time based multiplayer games. Users of such games both assume and require that game play interaction happens in near real-time and these games often support a large number of simultaneous players. Most networks are specialized to either voice traffic (such as the first and second generation of mobile networks) or data traffic (such as wired data networks). It is not clear that the requirements for such real time games can always be met on either type of network. The core of this thesis investigates the performance requirements real-time multiplayer games place on packet switched data networks and the connection between network impairments and game quality degradation. Traffic generated by network games distinguishes itself from other traffic both regarding its general characteristics and the requirements it places on the network. Understanding these traffic characteristics, requirements, and what consequences failures to support such requirements entail are of great importance when designing new networks in order to guarantee suitable quality of service for such real-time games.

  • 840.
    Ålemark, Niklas
    KTH, Tidigare Institutioner, Teleinformatik.
    Specification and development of animage acquisition and processing systemwith IR communications capabilities1996Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The GSM network has experienced a fast growth after its introduction in 1992. A large number of users in several countries in the word now have access to a standardised digital cellular network. This fact has lead to that the network is being used for several other things than voice communications. One such application is the transfer of pictures. This requires a unit that can digitise pictures and adapt the digital image information to the characteristics of the GSM network.

    This report describes the specification and development of an image acquisition and processing system with IR communications capabilities. It also outlines some of the possible applications for such a system.

  • 841.
    Åman, Erik
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    A Distributed Cachefor Very Large Objects2001Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Within a few years’ time, the Internet is expected to be used to transfer highquality video material and other bandwidth-demanding objects to a much larger extent than today. Users would prefer to be able to access such very large objects at an arbitrary point in time without any kind of preparation or advance planning. Offering such services on a large scale puts high demands on the network.

    Using a caching Web proxy server may increase the bandwidth and reliability perceived by the users while reducing the load on the network. This can be done transparently to the users.

    This thesis presents the principles for a caching Web proxy server better adapted to this expected traffic pattern. The bandwidth usage and transfer rate can be improved by taking advantage of the longer persistence of connections and by assuming that comparatively few objects will be popular at any given time. An experimental implementation has been developed in order to test the main principles. The new server is designed to operate in a distributed fashion by employing several cooperating servers at strategic points in the network. The system optimizes reliability and throughput by dynamically selecting from where to download objects based on current traffic and previous statistics.

  • 842.
    Åstrand, Erik
    Högskolan i Skövde, Institutionen för informationsteknologi.
    Rendering och manipulering av dom: Undersökning av AngularJS och ReactJS2016Independent thesis Basic level (university diploma), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Webben växer och webbapplikationer blir mer och mer komplexa och innehållsrika. Med detta så ska dessa växande applikationer även kunna presenteras på ett tilltalande och effektivt sätt. Jättarna Facebook, Twitter, Instagram och små bloggar har alla börjat använda sig av en teknik för att kunna dynamiskt ladda in ytterligare innehåll på en sida utan att behöva ladda om den. Denna teknik kallas för Infinite Scroll eller oändlig scrollning. Infinite Scroll kan resultera i enormt stort innehåll vilket tidigare studier visar på att det bidrar till bristande prestanda för rendering och manipulering av innehållet. Arbetet kommer utföra ett experiment där målet är att undersöka hur två populära SPA-ramverk AngularJS och ReactJS hanterar detta problem. 

  • 843.
    Ögren, Niklas
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Selecting/realization of Virtual Private Networks with Multiprotocol Label Switching or Virtual Local Area Networks2002Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Many reports have been written about the techniques behind Virtual Private Networks (VPN) and Multi Protocol Label Switching (MPLS). They usually deal with the low level design of the software implementing a specific technique. The initial products are usually not mature enough to run in a large network or have to be adjusted in some way to fit.

    This report investigates the different ways of implementing strict layer 2 Virtual Private Networks in an existing nation-wide Gigabit Ethernet. The infrastructure in use, as well as the hardware, has to be used without major changes. Since 1998/1999, when MPLS first started in the laboratories, development has continued. Today it is possible to introduce MPLS or tunneled national virtual local area network into an existing network. This requires high speed, fault tolerant, and stable hardware and software.

    Going beyond the separation of traffic at layer 3 using Virtual Private Networks, i.e., IPSec, we can tunnel layer 2 traffic through a network. Although the first layer 3 VPN products are already in use, layer 2 VPNs still need to be evaluated and brought into regular use. There are currently two ways of tunneling VLANs in a core network: tunneled VLANs (or as Extreme Networks calls them, VMANs) and MPLS.

    This project showed that it is possible to start with a VLAN-only solution, and then upgrade to MPLS to solve scalability issues. The VMAN solution can not be used at Arrowhead, since there are too many disadvantages in the way Extreme Networks has implemented it. However, a mix of tunneling VMAN in a VLAN core is possible, and enables customer tagging of VLANs in a Layer 2 VPN. Furthermore, the testing of EAPS and per-VLAN Spanning Tree Protocol turned out well, and showed that EAPS should not be used when there is more than one loop.

  • 844.
    Örn, Sara
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Realistic Multi-Cell Interference Coordination in 4G/LTE2012Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    In the LTE mobile system, all cells use the same set of frequencies. This means that a user could experience interference from other cells. A method that has been studied in order to reduce this interference and thereby increase data rate or system throughput is to coordinate scheduling between cells. Good results of this have been found in different studies. However, the interference is generally assumed to be known. Studies using estimated interference and simulating more than one cluster of cells have found almost no gain.

    This thesis will focus on how to use information from coordinated scheduling and other traffic estimates to do better interference estimation and link adaption. The suggested method is to coordinate larger clusters and use the coordination information, as well as estimates of which cells will be transmitting, to make estimates of interference from other cells. The additional information from interference estimation is used in the link adaptation. Limitations in bandwidth of the backhaul needed to send data between cells are considered, as well as the delay it may introduce. A limitation of the scope is that MIMO or HetNet scenarios have not been simulated.

    The suggested method for interference estimation and link adaptation have been implemented and simulated in a system simulator. The method gives a less biased estimate of SINR, but there are no gains in user bit rate. The lesser bias is since the method is better at predicting high SINR than the base estimate is. The lack of gains regarding user bit rate may result from the fact that in the studied scenarios, users where not able to make use of the higher estimated SINR since the base estimate is already high.

    The conclusion is that the method might be useful in scenarios where there are not full load, but the users either have bad channel quality or are able to make use of very high SINR. Such scenarios could be HetNet or MIMO scenarios, respectively.

  • 845.
    Öst, Albert
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för informationssystem och -teknologi.
    Evaluating LoRa and WiFi Jamming2018Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [en]

    Internet of Things changes our world with everything we have around us, our everyday things will be connected to the Internet. According to experts, in two years there will be up to 29 billion devices connected to the Internet. With all of the information that is produced it is important to keep the communication secure, otherwise there can be serious problems in the future. Therefore the objective with this study has been to investigate the area of jamming attacks on wireless communication for Internet of Things, more specifically on LoRa and WiFi technologies. This was made by a literature study to research about Internet of Things, the industrial side of it, the two communication technologies and wireless jamming of them. Additionally to this a small scale test bed system consisting of two LoRa nodes (an Arduino and a LoRa gateway), two WiFi nodes (a laptop and router) and a software defined radio frequency jammer (a HackRF One) were set up. Jamming was performed on the system and evaluated form the perspective of a typical industrial Internet of Things scenario. The testing on the system was done by measuring the received signal strength index, round trip time for a message and packet losses. The study showed that the WiFi communication broke down completely while the LoRa communication stood strong up to the jammer. This concluded that LoRa communication is secure for a typical Internet of Things scenario, from this particular jamming device, or a similar one.

  • 846.
    Österberg, Per
    Högskolan Väst, Institutionen för ekonomi och it, Avd för datateknik.
    A comparison between NS-2 and reality utilizing on queuing disciplines2012Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Eftersom dagens olika datornätverk växer sig större och mer komplexa har möjligheten att testa ny nätverksfunktionalitet försvårats. Detta har gjort att simulation har blivit populärt ibland utvecklare och forskare inom nätverksområdet. Nätverkssimulatorn NS-2 är en populär simulator som används flitigt av forskare och utvecklare runt om i världen. Men kan vi lita på att NS-2 simulatorns funktionalitet stämmer överens med verklighetens?Denna studie undersöker hur väl ett scenario i NS-2 simulatorn stämmer överens med ett verkligt scenario av samma typ. Vi har använt oss av ett topologi med en flaskhals där vi har testat tre olika kösystem på den strypta länken: Fair queuing, Random early detection och First in first out med Drop Tail. Genom flaskhalsen har vi skickat en UDP ström tillsammans med olika typer av trafik och mätt påverkan på UDP strömmen i form av tappade paket och genomströmning. Resultatet ifrån NS-2 simulatorn är sedan jämnfört med resultat ifrån samma scenario uppsatt i verkligheten.

  • 847.
    Östermark, Filip
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Performance Optimization of Virtualized Packet Processing Function for 5G RAN2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The advent of the fifth generation mobile networks (5G) presents many new challenges to satisfy the requirements of the upcoming standards. The 5G Radio Access Network (RAN) has several functions which must be highly optimized to keep up with increasing performance requirements. One such function is the Packet Processing Function (PPF) which must process network packets with high throughput and low latency. A major factor in the pursuit of higher throughput and lower latency is adaptability of 5G technology. For this reason, Ericsson has developed a prototype 5G RAN PPF as a Virtualized Network Function (VNF) using an extended version of the Data Plane Development Kit’s Eventdev framework, which can be run on a general purpose computer. This thesis project optimizes the throughput and latency of a 5G RAN PPF prototype using a set of benchmarking and code profiling tools to find bottlenecks within the packet processing path, and then mitigates the effects of these bottlenecks by changing the configuration of the PPF.

    Experiments were performed using IxNetwork to generate 2 flows with GTP-u/UDP/IPv4 packets for the PPF to process. IxNetwork was also used to measure throughput and latency of the PPF.

    The results show that the maximum throughput of the PPF prototype could be increased by 40.52% with an average cut-through latency of 97.59% compared to the default configuration in the evaluated test case, by reassigning the CPU cores, performing the packet processing work in fewer pipeline stages, and patching the RSS function of the packet reception (Rx) driver.

  • 848.
    Östlund, Pierre
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Design, implementation och simulering av ett MAC-protokoll för mobila trådlösa sensornätverk2014Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Trådlösa sensornätverk byggs upp av trådlösa sensorer, som gemensamt arbetar för att lösa en viss uppgift. Ett exempel på en sådan uppgift kan vara insamling av pollennivåer i luften över en stor yta. Sensornoderna vidarebefordrar datan sinsemellan tills den når en datainsamlingsnod någonstans i nätverket där den sedan lagras och efterbehandlas. Generellt gäller att sensornoder är små, billiga, kommunicerar trådlöst och har en väldigt lång livslängd. Traditionellt sett har sen- sornoder också antagits vara statiska (stillastående), vilket medför begränsningar om noderna bärs av exempelvis människor eller monteras på fordon.

    I detta examensarbete presenteras matmac , ett mac-protokoll som designats för att hantera mobila noder i trådlösa sensornätverk. En referensimplementa- tion av matmac har implementerats i operativsystemet Contiki och utvärderats med varierande konfigurationsparametrar, rörelsehastigheter och dataintensitet i simulatorn Cooja. Resultatet från utvärderingen visar att mekanismerna för mo- bilitetshantering i matmac främjar sensornodernas förmåga att pålitligt överföra data trots att de är mobila. 

  • 849.
    Östlund, Pontus
    KTH, Tidigare Institutioner, Teleinformatik.
    Integration of an optical network element in a TMN system1999Independent thesis Advanced level (degree of Master (Two Years)), 12 poäng / 18 hpOppgave
    Abstract [en]

    The objective of this thesis project was to investigate how to control a new type of hardware, an optical add-drop multiplexer, and integrate it into a management system. One section of the report covers the design of this control/management system. The hardware for the optical add-drop multiplexer is also described.

  • 850.
    Östman, Fredrik
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Automated Interface Switching for Wireless PDAs2001Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Mobility has become one of the major driving forces behind the Internet research effort for the last couple of years. Many large computer companies have begun to shift their focus and are trying to converge into the telecommunications and computing market. With the huge potential market of mobile/cellular phones to build on, hybrids between cellular phones and computers are a very lucrative and relatively new area. Recent efforts to bring traditional telecommunications closer to an IP based environment (for example the development and deployment of GPRS) have created new possibilities for the future of mobile systems. Personal Digital Assistants (PDAs) have been around for a couple of years, and they are getting ever more advanced and powerful. Considering how it will soon be very easy to connect these PDAs to the Internet (or any inter-, intranet), using faster and less expensive carriers and technology than ever before, and the new services that can be offered as a result, the market for - and usage of - PDAs have the potential to grow even more rapidly than before.

    This Master of Science Thesis will investigate the current and near future development of wireless PDAs, give an analysis of the most suitable technologies and discuss the new capabilities they can provide to consumers. Software for Microsoft Windows CE will be developed which manages the network interface selection for a PDA. The software, which will be integrated with Microsoft Windows CE, will automatically select the best interface for internetworking when two or more networks are available.

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