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  • 801.
    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.

  • 802.
    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.

  • 803.
    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.

  • 804.
    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.

  • 805.
    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.

  • 806.
    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.

  • 807.
    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.

  • 808.
    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.).

  • 809.
    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)
  • 810.
    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.

  • 811.
    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. 

  • 812.
    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.

  • 813.
    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.

  • 814.
    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.

  • 815.
    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.

  • 816.
    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.

  • 817.
    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.

  • 818.
    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.

  • 819.
    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.

  • 820.
    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.

  • 821.
    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.

  • 822.
    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.

  • 823.
    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.

  • 824.
    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. 

  • 825.
    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.

  • 826.
    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.

  • 827.
    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.

  • 828.
    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.

  • 829.
    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. 

  • 830.
    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.

  • 831.
    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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