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  • 1.
    A. Sani, Negar
    Linköping University, Department of Science and Technology, Physics and Electronics.
    M-PSK and M-QAM Modulation/Demodulation of UWB Signal Using Six-Port Correlator2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Nowadays high speed and high data rate communication are highly demanded. Consequently, wideband and high frequency transmitter and receivers should be designed. New transmitters and receivers should also have low power consumption, simple design and low manufacturing price in order to fulfill manufacturers’ requests for mass production. Having all above specifications, six-port correlator is a proper choice to be used as modulator and demodulator in transmitters and receivers.

    In this thesis the six-port correlator is introduced, modeled and simulated using Advanced Design System (ADS) software. A simple six-port transmitter/receiver system with a line of sight link is modeled and analyzed in BER, path length and noise terms. The modulation in this system is QAM, frequency is 7.5 GHz and symbol rate is 500 Msymbol/s.

    Furthermore two methods are proposed for high frequency and high symbol rate M-PSK and M-QAM modulation using six-port correlator. The 7.5 GHz modulators are modeled and simulated in ADS. Data streams generated by pseudo random bit generator with 1 GHz bandwidth are applied to modulators. Common source field effect transistors (FETs) with zero bias are used as controllable impedance termination to apply baseband data to modulator. Both modulators show good performance in M-PSK and M-QAM modulation.

  • 2. Abadal, Sergi
    et al.
    Alarcon, Eduard
    Cabellos-Aparicio, Albert
    Lemme, Max C.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Nemirovsky, Mario
    Graphene-Enabled Wireless Communication for Massive Multicore Architectures2013In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 51, no 11, 137-143 p.Article in journal (Refereed)
    Abstract [en]

    Current trends in microprocessor architecture design are leading towards a dramatic increase of core-level parallelization, wherein a given number of independent processors or cores are interconnected. Since the main bottleneck is foreseen to migrate from computation to communication, efficient and scalable means of inter-core communication are crucial for guaranteeing steady performance improvements in many-core processors. As the number of cores grows, it remains unclear whether initial proposals, such as the Network-on-Chip (NoC) paradigm, will meet the stringent requirements of this scenario. This position paper presents a new research area where massive multicore architectures have wireless communication capabilities at the core level. This goal is feasible by using graphene-based planar antennas, which can radiate signals at the Terahertz band while utilizing lower chip area than its metallic counterparts. To the best of our knowledge, this is the first work that discusses the utilization of graphene-enabled wireless communication for massive multicore processors. Such wireless systems enable broadcasting, multicasting, all-to-all communication, as well as significantly reduce many of the issues present in massively multicore environments, such as data coherency, consistency, synchronization and communication problems. Several open research challenges are pointed out related to implementation, communications and multicore architectures, which pave the way for future research in this multidisciplinary area.

  • 3.
    Abbasi, Abdul Ghafoor
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture (Closed 20120101), Communication Systems, CoS (closed 2012-01-01).
    Muftic, Sead
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture (Closed 20120101), Communication Systems, CoS (closed 2012-01-01).
    Mumtaz, Shahzad Ahmed
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture (Closed 20120101), Communication Systems, CoS (closed 2012-01-01).
    Security extensions of windows environment based on FIPS 201 (PIV) smart card2011In: World Congr. Internet Secur., WorldCIS, 2011, 86-92 p.Conference paper (Refereed)
    Abstract [en]

    This paper describes security extensions of various Windows components based on usage of FIPS 201 (PIV) smart cards. Compared to some other similar solutions, this system has two significant advantages: first, smart cards are based on FIPS 201 standard and not on some proprietary technology; second, smart card security extensions represent an integrated solution, so the same card is used for security of several Microsoft products. Furthermore, our smart card system uses FIPS 201 applet and middleware with smart card APIs, so it can also be used by other developers to extend their own applications with smart card functions in a Windows environment. We support the following security features with smart cards: start-up authentication (based on PIN and/or fingerprint), certificate-based domain authentication, strong authentication, and protection of local resources. We also integrated our middleware and smart cards with MS Outlook and MS Internet Explorer.

  • 4.
    Abbasi, Mahdi
    University of Gävle, Department of Technology and Built Environment.
    Characterization of a 5GHz Modular Radio Frontend for WLAN Based on IEEE 802.11p2008Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The number of vehicles has increased significantly in recent years, which causeshigh density in traffic and further problems like accidents and road congestions.A solution regarding to this problem is vehicle-to-vehicle communication, wherevehicles are able to communicate with their neighboring vehicles even in the absenceof a central base station, to provide safer and more efficient roads and toincrease passenger safety.The goal of this thesis is to investigate basic physical layer parameters of ainter-vehicle communication system, like emission power, spectral emission, errorvector magnitude, guard interval, ramp-up/down time, and third order interceptpoint. I also studied the intelligent transportation system’s channel layout inEurope, how the interference of other systems are working in co-channel and adjacentchannels, and some proposals to use the allocated frequency bands. On theother hand, the fundamentals of OFDM transmission and definitions of OFDMkey parameters in IEEE 802.11p are investigated.The focus of this work is on the measurement of transmitter frontend parametersof a new testbed designed and fabricated in order to be used at inter-vehiclecommunication based on IEEE 802.11p.

  • 5.
    Abdelsamad, Deena
    Blekinge Institute of Technology, School of Engineering.
    Video Transmission Jerkiness Measure2013Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [en]

    Digital video transmission is widely used nowadays in multimedia. Frame dropping, freeze and reduced number of frames in the transmitted video are common symptoms of bad transmission quality. In order to assess the quality of transmission, a criterion is introduced in a model for a no reference video jerkiness measure [3]. This model is dierent from the former models presented as it depends on viewing conditions and video resolutions, so it is applicable for any frame size from QCIF to HD. The model uses simple mathematical equations of jerkiness and can be used for any video sequence [3]. A model of reduced reference method (Qtransmission) which depends on a pre-measured Jerkiness is introduced as a suggestion of future work.

  • 6.
    Abelsson, Sara
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Propagation Measurements at 3.5 GHz for WiMAX2007Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    Propagation measurements at the frequency 3.5 GHz for the WiMAX technology have been conducted. The purpose of these measurements is that a coverage analysis should be accomplished. The mathematical software package MATLAB has been used to analyze the collected data from the measurement campaign. Path loss models have also been used and a comparison between these models and the collected data has been performed. An analysis prediction tool from an application called WRAP has also been used in the comparison with the collected data. In this thesis, diff

  • 7. Abeywickrama, Sandu
    et al.
    Furdek, Marija
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Wong, Elaine
    Protecting core networks with dual-homing: A study on enhanced network availability, resource efficiency, and energy-savings2016In: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 381, 327-335 p.Article in journal (Refereed)
    Abstract [en]

    Core network survivability affects the reliability performance of telecommunication networks and remains one of the most important network design considerations. This paper critically examines the benefits arising from utilizing dual-homing in the optical access networks to provide resource-efficient protection against link and node failures in the optical core segment. Four novel, heuristic-based RWA algorithms that provide dedicated path protection in networks with dual-homing are proposed and studied. These algorithms protect against different failure scenarios (i.e. single link or node failures) and are implemented with different optimization objectives (i.e., minimization of wavelength usage and path length). Results obtained through simulations and comparison with baseline architectures indicate that exploiting dual-homed architecture in the access segment can bring significant improvements in terms of core network resource usage, connection availability, and power consumption.

  • 8. Abrardo, A
    et al.
    Fodor, Gabor
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Tola, B.
    Network coding schemes for Device-To-Device communications based relaying for cellular coverage extension2015In: IEEE Workshop on Signal Processing Advances in Wireless Communications, SPAWC, 2015, 670-674 p.Conference paper (Refereed)
    Abstract [en]

    In this paper, we study the performance of device-To-device (D2D) based range extension in terms of sum rate and power efficiency when a relaying user equipment (UE) helps to improve the coverage for cell-edge UEs. In our design, the relaying UE has own traffic to transmit and receive to/from the cellular base station (BS) and can operate either in amplify-And-forward (AF) or decode-And-forward (DF) modes and can make use of either digital or analogue (PHY layer) network coding. In this rather general setting, we propose mode selection, resource allocation and power control schemes and study their performance by means of system simulations. We find that the performance of the DF scheme with network coding is superior both to the traditional cellular and the AF based relaying schemes, including AF with two-slot or three-slot PHY layer network coding.

  • 9.
    Abrego peris, Iñaki
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    Antenna with medical applications for tumour cancer: hyperthermia function2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The idea is to improve or help the treatments that exist in the market in the medical field. Treatments such as mammography or radiotherapy make use of X-rays. X-rays are electromagnetic radiation in a high frequency band, this type of electromagnetic is dangerous to health because ionizing radiation is used, ionized atoms interact with matter. For this reason, in our work we give alternative solution to these treatments without any risk to health. This project consists in the use of non-harmful frequencies such as microwave. In this way, we will make an antenna with medical applications whose frequency range will be between 300 MHz and 30 GHz, specifically between 950MHz and 2.45GHz (medical range). The first step will be the detection of the tumour and classification of this, but our work is about another technique called hyperthermia. This technique consists in increase the temperature with a value of 40-43 degrees in the tumour area. Tumour resistance decreases when heat is applied to this. When combining a treatment with oncologic hyperthermia, the effect of radiotherapy is most effective (between 1.5-5 times). The most important part is study antenna in body tissues characteristics as SAR, depth penetration and antenna size; this theory part is essential to know the best parameters and what case use this. In work development we will choose and design antennas for the different parts of the body in some specific frequencies and choose circular antennas in frequencies of 915 MHz and 1.8 GHz. Finally, we will take measurements about temperature increase with meat and say some conclusions.

  • 10.
    Abualhana, Munther
    et al.
    Blekinge Institute of Technology, School of Computing.
    Tariq, Ubaid
    Blekinge Institute of Technology, School of Computing.
    Improving QoE over IPTV using FEC and Retransmission2009Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    IPTV (Internet Protocol Television), a new and modern concept of emerging technologies with focus on providing cutting edge high-resolution television, broadcast, and other fascinating services, is now easily available with only requirement of high-speed internet. Everytime a new technology is made local, it faces tremendous problems whether from technological point of view to enhance the performance or when it comes down to satisfy the customers. This cutting edge technology has provided researchers to embark and play with different tools to provide better quality while focusing on existing tools. Our target in dissertation is to provide a few interesting facets of IPTV and come up with a concept of introducing an imaginary cache that can re-collect the packets travelling from streaming server to the end user. In the access node this cache would be fixed and then on the basis of certain pre-assumed research work we can conclude how quick retransmission can take place when the end user responds back using RTCP protocol and asks for the retransmission of corrupted/lost packets. In the last section, we plot our scenario of streaming server on one side and client, end user on the other end and make assumption on the basis of throughput, response time and traffic.

  • 11. Abu-Lebdeh, Mohammad
    et al.
    Sahoo, Jagruti
    Glitho, Roch
    KTH.
    Tchouati, Constant Wette
    Cloudifying the 3GPP IP Multimedia Subsystem for 4G and Beyond: A Survey2016In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 54, no 1, 91-97 p.Article in journal (Refereed)
    Abstract [en]

    4G systems have been continuously evolving to cope with the emerging challenges of human-centric and M2M applications. Research has also now started on 5G systems. Scenarios have been proposed and initial requirements derived. 4G and beyond systems are expected to easily deliver a wide range of human-centric and M2M applications and services in a scalable, elastic, and cost-efficient manner. The 3GPP IMS was standardized as the service delivery platform for 3G networks. Unfortunately, it does not meet several requirements for provisioning applications and services in 4G and beyond systems. However, cloudifying it will certainly pave the way for its use as a service delivery platform for 4G and beyond. This article presents a critical overview of the architectures proposed so far for cloudifying the IMS. There are two classes of approaches; the first focuses on the whole IMS system, and the second deals with specific IMS entities. Research directions are also discussed. IMS granularity and a PaaS for the development and management of IMS functional entities are the two key directions we currently foresee.

  • 12.
    Abusubaih, Murad
    et al.
    Telecommun. Networks Group, Technische Univ. Berlin.
    Gross, James
    Telecommun. Networks Group, Technische Univ. Berlin.
    Wiethoelter, Sven
    Telecommun. Networks Group, Technische Univ. Berlin.
    Wolisz, Adam
    Telecommun. Networks Group, Technische Univ. Berlin.
    On Access Point Selection in IEEE 802.11 Wireless Local Area Networks2006In: 31st IEEE Conference on Local Computer Networks, Proceedings 2006, IEEE conference proceedings, 2006, 879-886 p.Conference paper (Refereed)
    Abstract [en]

    In wireless local area networks often a station can potentially associate with more than one access point. Therefore, a relevant question is which access point to select "best" from a list of candidate ones. In IEEE 802.11, the user simply associates to the access point with the strongest received signal strength. However, this may result in a significant load imbalance between several access points, as some accommodate a large number of stations while others are lightly loaded or even idle. Moreover, the multi-rate flexibility provided by several IEEE 802.11 variants can cause low bit rate stations to negatively affect high bit rate ones and consequently degrade the overall network throughput. This paper investigates the various aspects of "best" access point selection for IEEE 802.11 systems. In detail, we first derive a decision metric the selection can be based on. Using this metric we propose two new selection mechanisms which are decentralized in the sense that the decision is performed by each station, given appropriate status information of each access point. In fact, only few bytes of status information have to be added to the beacon and probe response frames which does not impose significant overhead. In addition, we show that our mechanism improves station quality of service and better utilizes network resources compared to the conventional one implemented today in IEEE 802.11 devices.

  • 13.
    Abusubaih, Murad
    et al.
    Technische Universit¨at Berlin.
    Gross, James
    Technische Universit¨at Berlin.
    Wolisz, Adam
    Technische Universit¨at Berlin.
    An Inter-Access Point Coordination Protocol for Dynamic Channel Selection in IEEE802.11 Wireless LANs2007Conference paper (Refereed)
    Abstract [en]

    This paper presents and evaluates an Inter-Access Point Coordination protocol for dynamic channel selection in IEEE 802.11 WLANs. It addresses an open issue for the implementation of many distributed and centralized dynamic channel selection policies proposed to mitigate interference problems in Wireless LANs (WLANs). The presented protocol provides services to a wide range of policies that require different levels of coordination among APs by enabling them to actively communicate and exchange information. An Intra-Cell protocol that enables interaction between the AP and its accommodated stations to handle channel switching within the same cell is also presented.

  • 14.
    Abusubaih, Murad
    et al.
    TU Berlin.
    Wiethoelter, Sven
    TU Berlin.
    Gross, James
    Wolisz, Adam
    TU Berlin.
    A New Access Point Selection Policy for Multi-Rate IEEE 802.11 WLANs2008In: International Journal of Parallel, Emergent and Distributed Systems, ISSN 1744-5760, E-ISSN 1744-5779, Vol. 23, no 4, 291-307 p.Article in journal (Refereed)
    Abstract [en]

    In wireless local area networks, often a station can potentially associate with more than one access point (AP). Therefore, a relevant question is which AP to select 'best' from a list of candidate ones. In IEEE 802.11, the user simply associates to the AP with the strongest received signal strength. However, this may result in a significant load imbalance between several APs. Moreover, the multi-rate flexibility provided by several IEEE 802.11 variants can cause low bit rate stations to negatively affect high bit rate ones and consequently degrade the overall network throughput. This paper investigates the various aspects of 'best' AP selection for IEEE 802.11 systems. In detail, we first derive a new decision metric which can be used for AP selection. Using this metric, we propose two new selection mechanisms which are decentralised in the sense that the decision is performed by each station, given appropriate status information of each AP. In fact, only few bytes of status information have to be added to the Beacon and Probe Response frames which does not impose significant overhead. We show that our mechanism improves mean quality of service of all stations and better utilises network resources compared to the conventional one implemented today in IEEE 802.11 devices. Also, the schemes are appealing in terms of stability and provide their performance improvement even for denser or lighter network configurations.

  • 15.
    Adam, Constantin
    KTH, School of Electrical Engineering (EES).
    A Middleware for Self-Managing Large-Scale Systems2006Doctoral thesis, monograph (Other scientific)
    Abstract [en]

    This thesis investigates designs that enable individual components of a distributed system to work together and coordinate their actions towards a common goal. While the basic motivation for our research is to develop engineering principles for large-scale autonomous systems, we address the problem in the context of resource management in server clusters that provide web services.

    To this end, we have developed, implemented and evaluated a decentralized design for resource management that follows four principles. First, in order to facilitate scalability, each node has only partial knowledge of the system. Second, each node can adapt and change its role at runtime. Third, each node runs a number of local control mechanisms independently and asynchronously from its peers. Fourth, each node dynamically adapts its local configuration in order to optimize a global utility function.

    The design includes three fundamental building blocks: overlay construction, request routing and application placement. Overlay construction organizes the cluster nodes into a single dynamic overlay. Request routing directs service requests towards nodes with available resources. Application placement partitions the cluster resources between applications, and dynamically adjusts the allocation in response to changes in external load, node failures, etc.

    We have evaluated the design using complexity analysis, simulation and prototype implementation. Using complexity analysis and simulation, we have shown that the system is scalable, operates efficiently in steady state, quickly adapts to external events and allows for effective service differentiation by a system administrator. A prototype has been built using accepted technologies (Java, Tomcat) and evaluated using standard benchmarks (TPC-W and RUBiS). The evaluation results show that the behavior of the prototype matches closely that of the simulated design for key metrics related to adaptability and robustness, therefore validating our design and proving its feasibility.

  • 16.
    Adam, Constantin
    KTH, School of Electrical Engineering (EES).
    Scalable Self-Organizing Server Clusters with Quality of Service Objectives2005Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Advanced architectures for cluster-based services that have been recently proposed allow for service differentiation, server overload control and high utilization of resources. These systems, however, rely on centralized functions, which limit their ability to scale and to tolerate faults. In addition, they do not have built-in architectural support for automatic reconfiguration in case of failures or addition/removal of system components.

    Recent research in peer-to-peer systems and distributed management has demonstrated the potential benefits of decentralized over centralized designs: a decentralized design can reduce the configuration complexity of a system and increase its scalability and fault tolerance.

    This research focuses on introducing self-management capabilities into the design of cluster-based services. Its intended benefits are to make service platforms dynamically adapt to the needs of customers and to environment changes, while giving the service providers the capability to adjust operational policies at run-time.

    We have developed a decentralized design that efficiently allocates resources among multiple services inside a server cluster. The design combines the advantages of both centralized and decentralized architectures. It allows associating a set of QoS objectives with each service. In case of overload or failures, the quality of service degrades in a controllable manner. We have evaluated the performance of our design through extensive simulations. The results have been compared with performance characteristics of ideal systems.

  • 17.
    Adam, Constantin
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Stadler, Rolf
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    A Middleware Design for Large-scale Clusters offering Multiple Services2006In: IEEE Transactions on Network and Service Management, ISSN 1932-4537, Vol. 3, no 1, 1-12 p.Article in journal (Refereed)
    Abstract [en]

    We present a decentralized design that dynamically allocates resources to multiple services inside a global server cluster. The design supports QoS objectives (maximum response time and maximum loss rate) for each service. A system administrator can modify policies that assign relative importance to services and, in this way, control the resource allocation process. Distinctive features of our design are the use of an epidemic protocol to disseminate state and control information, as well as the decentralized evaluation of utility functions to control resource partitioning among services. Simulation results show that the system operates both effectively and efficiently; it meets the QoS objectives and dynamically adapts to load changes and to failures. In case of overload, the service quality degrades gracefully, controlled by the cluster policies.

  • 18.
    Adam, Constantin
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Stadler, Rolf
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Adaptable Server Clusters with QoS Objectives2005In: Integrated Network Management IX - MANAGING NEW NETWORKED WORLDS / [ed] Clemm A, Festor O, Pras A, New York: IEEE , 2005, 149-163 p.Conference paper (Refereed)
    Abstract [en]

    We present a decentralized design for a server cluster that supports a single service with response time guarantees. Three distributed mechanisms represent the key elements of our design. Topology construction maintains a dynamic overlay of cluster nodes. Request routing directs service requests towards available servers. Membership control allocates/releases servers to/from the cluster, in response to changes in the external load. We advocate a decentralized approach, because it is scalable, fault-tolerant, and has a lower configuration complexity than a centralized solution. We demonstrate through simulations that our system operates efficiently by comparing it to an ideal centralized system. In addition, we show that our system rapidly adapts to changing load. We found that the interaction of the various mechanisms in the system leads to desirable global properties. More precisely, for a fixed connectivity c (i.e., the number of neighbors of a node in the overlay), the average experienced delay in the cluster is independent of the external load. In addition, increasing c increases the average delay but decreases the system size for a given load. Consequently, the cluster administrator can use c as a management parameter that permits control of the tradeoff between a small system size and a small experienced delay for the service.

  • 19.
    Adam, Constantin
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Stadler, Rolf
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Externally Controllable, Self-Oganizing Server Clusters2005In: Designing a Scalable, Self-organizing Middleware for Server Clusters (NGNM05): in the scope of Networking 2005, 2005, 1-12 p.Chapter in book (Other academic)
  • 20.
    Adam, Constantin
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Stadler, Rolf
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Implementation and evaluation of a middleware for self-organizing decentralized web services2006In: Integrated Network Management IX: MANAGING NEW NETWORKED WORLDS, 2006, Vol. 3996, 1-14 p.Conference paper (Refereed)
    Abstract [en]

    We present the implementation of Chameleon, a peer-to-peer middleware for self-organizing web services, and we provide evaluation results from a test bed. The novel aspect of Chameleon is that key functions, including resource allocation, are decentralized, which facilitates scalability and robustness of the overall system. Chameleon is implemented in Java on the Tomcat web server environment. The implementation is non-intrusive in the sense that it does not require code modifications in Tomcat or in the underlying operating system. We evaluate the system by running the TPC-W benchmark. We show that the middleware dynamically and effectively reconfigures in response to changes in load patterns and server failures, while enforcing operating policies, namely, QoS objectives and service differentiation under overload.

  • 21.
    Adam, Constantin
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Stadler, Rolf
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Patterns for Routing and Self-Stabilization2004In: NOMS 2004: IEEE/IFIP NETWORK OPERATIONS AND MANAGMENT SYMPOSIUM - MANAGING NEXT GENERATION CONVERGENCE NETWORKS AND SERVICES, New York: IEEE , 2004, 61-74 p.Conference paper (Refereed)
    Abstract [en]

    This paper contributes towards engineering self-stabilizing networks and Services. We propose the use of navigation patterns, which define how information for state updates is disseminated in the system, as fundamental building blocks for self-stabilizing systems. We present two navigation patterns for self-stabilization: the progaressive wave pattern and the stationary wave pattern. The progressive wave pattern defines the update dissemination in Internet routing systems running the DUAL and OSPF protocols. Similarly, the stationary wave pattern defines the interactions of peer nodes in structured-peer-to-peer systems, including Chord, Pastry, Tapestry, and CAN. It turns out that both patterns are related. They both disseminate information in form of waves, i.e, sets of messages that originate from single events. Patterns can be instrumented to obtain wave statistics, which enables monitoring the process of self-stabilization in a system. We focus on Internet routing and peer-to-peer systems in this work, since we believe that studying these (existing) systems can lead to engineering principles for self-stabilizing system in various application areas.

  • 22.
    Adam, Constantin
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Stadler, Rolf
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Service middleware for self-managing large-scale systems2007In: IEEE Transactions on Network and Service Management, ISSN 1932-4537, Vol. 4, no 3, 50-64 p.Article in journal (Refereed)
    Abstract [en]

    Resource management poses particular challenges in large-scale systems, such as server clusters that simultaneously process requests from a large number of clients. A resource management scheme for such systems must scale both in the in the number of cluster nodes and the number of applications the cluster supports. Current solutions do not exhibit both of these properties at the same time. Many are centralized, which limits their scalability in terms of the number of nodes, or they are decentralized but rely on replicated directories, which also reduces their ability to scale. In this paper, we propose novel solutions to request routing and application placementtwo key mechanisms in a scalable resource management scheme. Our solution to request routing is based on selective update propagation, which ensures that the control load on a cluster node is independent of the system size. Application placement is approached in a decentralized manner, by using a distributed algorithm that maximizes resource utilization and allows for service differentiation under overload. The paper demonstrates how the above solutions can be integrated into an overall design for a peer-to-peer management middleware that exhibits properties of self-organization. Through complexity analysis and simulation, we show to which extent the system design is scalable. We have built a prototype using accepted technologies and have evaluated it using a standard benchmark. The testbed measurements show that the implementation, within the parameter range tested, operates efficiently, quickly adapts to a changing environment and allows for effective service differentiation by a system administrator.

  • 23.
    Adam, Constantin
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Stadler, Rolf
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Tang, Chunqiang
    Steinder, Malgorzata
    Spreitzer, Michael
    A service middleware that scales in system size and applications2007In: 2007 10TH IFIP/IEEE INTERNATIONAL SYMPOSIUM ON INTEGRATED NETWORK MANAGEMENT (IM 2009): VOLS 1 AND 2, NEW YORK: IEEE , 2007, 70-79 p.Conference paper (Refereed)
    Abstract [en]

    We present a peer-to-peer service management middleware that dynamically allocates system resources to a large set of applications. The system achieves scalability in number of nodes (1000s or more) through three decentralized mechanisms that run on different time scales. First, overlay construction interconnects all nodes in the system for exchanging control and state information. Second, request routing directs requests to nodes that offer the corresponding applications. Third, application placement controls the set of offered applications on each node, in order to achieve efficient operation and service differentiation. The design supports a large number of applications (100s or more) through selective propagation of configuration information needed for request routing. The control load on a node increases linearly with the number of applications in the system. Service differentiation is achieved through assigning a utility to each application which influences the application placement process. Simulation studies show that the system operates efficiently for different sizes, adapts fast to load changes and failures and effectively differentiates between different applications under overload.

  • 24.
    Adams, David C.
    et al.
    MIT.
    Du, Jinfeng
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Communication Theory. Massachusetts Institute of Technology, USA.
    Médard, Muriel
    Department of Electrical Engineering and Computer Science, MIT.
    Yu, Christopher C.
    Draper Laboratory.
    Delay constrained throughput-reliability tradeoff in network-coded wireless systems2014Conference paper (Refereed)
    Abstract [en]

    We investigate the performance of delay constrained data transmission over wireless networks without end-to-end feedback. Forward error-correction coding (FEC) is performed at the bit level to combat channel distortions and random linear network coding (RLNC) is performed at the packet level to recover from packet erasures. We focus on the scenario where RLNC re-encoding is performed at intermediate nodes and we assume that any packet that contains bit errors after FEC decoding can be detected and erased. To facilitate explicit characterization of data transmission over network-coded wireless systems, we propose a generic two-layer abstraction of a network that models both bit/symbol-level operations at the lower layer (termed PHY-layer) over several heterogeneous links and packet-level operations at the upper layer (termed NET-layer). Based on this model, we propose a network reduction method to characterize the throughput-reliability function of the end-to-end transmission. Our approach not only reveals an explicit tradeoff between data delivery rate and reliability, but also provides an intuitive visualization of the bottlenecks within the underlying network. We illustrate our approach via a point-to-point link and a relay network and highlight the advantages of this method over capacity-based approaches.

  • 25.
    Adapa, Sasank Sai Sujan
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    APPLYING LEAN PRINCIPLES FOR PERFORMANCE ORIENTED SERVICE DESIGN OF VIRTUAL NETWORK FUNCTIONS FOR NFV INFRASTRUCTURE: Concepts of Lean2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Context. Network Function Virtualization was recently proposed by European Telecommunications Standards Institute (ETSI) to improve the network service flexibility by virtualization of network services and applications that run on hardware. To virtualize network functions, the software is decoupled from underlying physical hardware. NFV aims to transform industries by reducing capital investments on hardware by using commercial-of-the-shelf (COTS) hardware. NFV makes rapid innovative growth in telecom services through software based service deployment.

    Objectives. This thesis work aims to investigate how business organizations function and the roles in defining a service relationship model. The work also aims to define a service relationship model and to validate it via proof of concept using network function virtualization as a service. For this thesis, we finally apply lean principles for the defined service relationship model to reduce waste and investigate how lean benefits the model to be proven as performance service oriented.

    Methods. The essence of this work is to make a business organization lean by investigating its actions and applying lean principles. To elaborate, this thesis work involves in a research of papers from IEEE, TMF, IETF and Ericsson. It results in modelling of a PoC by following requirement analysis methodology and by applying lean principles to eliminate unnecessary processes which doesn’t add any value.

    Results. The results of the work include a full-fledged service relationship model that include three service levels with roles that can fit in to requirement specifications of NFV infrastructure. The results also show the service levels functionalities and their relationships between the roles. It has also been observed that the services that are needed to be standardized are defined with syntax for ways to describe network functions. It is observed that lean principles benefit the service relationship model from reducing waste factors and hereby providing a PoC which is performance service oriented.

    Conclusions. We conclude that roles defined are fit for the service relationship model designed. Moreover, we conclude that the model can hence contain the flow of service by standardizing the subservices and reducing waste interpreted with lean principles and there is a need for further use case proof of the model in full scale industry trials. It also concludes the ways to describe network functions syntax which follows lean principles that are essential to have them for the sub-services standardization. However, PoC defined can be an assurance to the NFV infrastructure.

  • 26.
    Addu, Raj Kiran
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Potuvardanam, Vinod Kumar
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Effect of Codec Performance on Video QoE for videos encoded with Xvid, H.264 and WebM/VP82014Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    In recent years, there has been a significant growth in multimedia services such as mobile video streaming, Video-on-Demand and video conferencing. This has led to the development of various video coding techniques, aiming to deliver high quality video while using available bandwidth efficiently. This upsurge in the usage of video applications has also resulted in making endusers more quality-conscious. In order to meet the users’ expectations, the Quality of Experience (QoE) studies has gained utmost importance from both researchers and service providers. This thesis aims to compare the performance of H.264/AVC, Xvid and WebM/VP8 video codecs in wired and wireless networks. The codec performance is evaluated for different packet loss and delay variation values. The evaluation of codec performance is done using both subjective and objective assessment methods. In subjective assessment method, the evaluation of video codec performance is done using ITU-T recommended Absolute Category Rating (ACR) method. Using this method the perceptual video quality ratings are taken from the users, which are then averaged to obtain Mean Opinion Score. These obtained scores are used to analyze the performance of encoded videos with respect to users’ perception. In addition to subjective assessment method, the quality of encoded video is also measured using objective assessment method. The objective metric SSIM (Structural Similarity) is used to evaluate the performance of encoded videos. Based on the results, it was found that for lower packet loss and delay variation values H.264 showed better results when compared to Xvid and WebM/VP8 whereas, WebM/VP8 outperformed Xvid and H.264 for higher packet loss and delay variation values. On the whole, H.264 and WebM/VP8 performed better than Xvid. It was also found that all three video codecs performed better in wired network when compared to the wireless network.

  • 27.
    Adebomi, OYEKANLU Emmanuel
    et al.
    Blekinge Institute of Technology, School of Computing.
    Mwela, JOHN Samson
    Blekinge Institute of Technology, School of Computing.
    Impact of Packet Losses on the Quality of Video Streaming2010Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    In this thesis, the impact of packet losses on the quality of received videos sent across a network that exhibit normal network perturbations such as jitters, delays, packet drops etc has been examined. Dynamic behavior of a normal network has been simulated using Linux and the Network Emulator (NetEm). Peoples’ perceptions on the quality of the received video were used in rating the qualities of several videos with differing speeds. In accordance with ITU’s guideline of using Mean Opinion Scores (MOS), the effects of packet drops were analyzed. Excel and Matlab were used as tools in analyzing the peoples’ opinions which indicates the impacts that different loss rates has on the transmitted videos. Statistical methods used for evaluation of data are mean and variance. We conclude that people have convergence of opinions when losses become extremely high on videos with highly variable scene changes

  • 28.
    Adeleke, Adesina
    Blekinge Institute of Technology, School of Management.
    How External Forces are influencing the Ebusiness strategy of MTN-Nigeria2009Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    The Internet and e-business has had enormous impact on many companies in Nigeria and there has been much research on how e-business influences the environment, but little can be found on how the environment of a developing country like Nigeria influences e-business. In e-business, technology tells the business what can be done in smarter ways. Technology not only can make business more efficient but also can make business more effective in targeting and reaching markets, however technology cannot enhance business in isolation as there are other vital factors that equally impact business. This thesis presents an adapted version of the PESTEL (Political, Economic, Socio cultural, Technology, Environment, and Legal) framework so called e-business PESTEL framework, as a method for structural analysis of macro environment forces in the future. In addition to this PESTEL framework, the Porter’s five forces model was employed to analyse the industrial forces that also influence MTNN e-business strategy. The main goal of this research is to give an overview of industry and macro-environment forces influencing the e-business strategy MTN-Nigeria and the impact of future developments. The research methodology was explorative and descriptive. A further method for future analysis of the macro-environments influences and a suggestion on how to incorporate it in this research work is given. The e-business strategy of MTNN consists of four areas: E-procurement, E-collaboration (CRM), Supply chain management and E-commerce. The influences found on macro-environments level are political and sociocultural forces and in the industry levels are bargaining power of customers and suppliers of its products and services .The most recommendations are that MTN-Nigeria should add e-business PESTEL framework described in this thesis to its e-business strategy check. Furthermore MTNN should include environment analysis more extensively in their e-business strategy approach as the factors in this research work shape the environment in which it carries out its business.

  • 29.
    ADIL, MUHAMMAD NAEEM
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Analysis and Optimization of Transmission Strategies for Two Hop Networks with Multiple Antennas2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Two hop relay based networks consist of three network nodes: source,relay station, and destination in which relay station assists the sourceto communicate reliably and efficiently with the destination. Moreover,these networks provide cost efficient solution for achieving highdata rate via cooperative communication between relays with singleantennas. In two hop relay based networks, communication from a source todestination takes place over two phases, i.e , in first phase from sourceto relay station and in second phase from relay station to the destination.Therefore, it is essential to formulate transmission strategies,i.e, TDMA, SDMA, Hybrid TDMA-SDMA and multicast in terms ofresource allocation, beamforming over two phases so that interferenceis taken into account and high data rates are achieved. In this thesis,some relay selection methods have been proposed to optimize thenetwork performance. Different proposed transmission strategies arecompared in different scenario settings in order to analyse and decidethe best strategy in each setting. Based upon simulation results it is recommended to use adaptivetime split ratio between the two phases. Brute force relay selection givesthe optimal relay assignment but Hungarian assignment algorithm alsoperforms pretty close to brute force performance. SDMA with cooperativerelays connection with multiple antennas at the relays performsmuch better than the other transmission strategies. However, multicaststrategy performs much better if second phase channel knowledge is notavailable at the base station.

  • 30.
    Adolfsson, Henrik
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Svensson, Peter
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Design and implementation of the MMS portal2006Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [en]

    MMS-enabled terminals on the market today are very complicated to use. It takes several steps to create a multi-slide MMS-message with images and text. This discourages users from using it. To increase usage of MMS, several companies provide web-based or stand-alone programs that allow users to create and send MMS-messages from a regular computer. However these editors have many limitations and are not user-friendly. This thesis describes the design and implementation of a user-friendly web-based MMS-portal where users can create, edit and send MMS-messages. The portal is integrated into Densitet’s system for development of mobile services. Conclusions that can be draw from this work are that problems with MMS interoperability have mostly the poor standardization to blame. Different terminals support different types of images and sound formats, and to make the MMS-portal user-friendly, format conversions of uploaded content had to be implemented. Also the MMS-portal only supports basic MMS-functionality. If the MMS-specification includes more audio and image formats and if the MMS-terminals are upgraded to handle these formats, sending MMS-messages will be easier and mobile messaging will continue to grow.

  • 31.
    Afaq, Muhammad
    et al.
    Blekinge Institute of Technology, School of Engineering.
    Faheem, Sahibzada Muhammad
    Blekinge Institute of Technology, School of Engineering.
    Performance Analysis of Selected Cooperative Relaying Techniques2010Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Recently, cooperative communication has gained significant interest due to the fact that it exploits spatial diversity and provides capacity/performance gain over conventional single- input single-output (SISO) systems. A mobile node with single antenna can cooperate with a nearby mobile node having single antenna in multi-user environment to create the effect of virtual multiple antenna system. Hence, reducing the complexity associated with actual multiple antenna systems. Despite the small size and power constraints, a mobile node can still benefit from spatial diversity by employing cooperation, thus saving transmission power and increasing the coverage range of the network. In this thesis, we have selected some of relaying protocols, namely, amplify-and-forward, decode-and-forward, detect-and-forward, and selective detect-and-forward that are studied and implemented for two different relaying geometries, i.e. equidistant and collinear. Results are studied and compared with each other to show the performance of each protocol in terms of average symbol error probabilities. The considered system model has three nodes, i.e. source, relay, destination. Communicating nodes are considered to be half-duplex with single antenna for transmission and reception. The source, when communicating with the destination, broadcasts the information, which is heard by the nearby relay. The relay then uses one of the cooperation protocols. Finally, the relayed signal reaches the destination, where it is detected by maximal ratio combiner (MRC) and combined with the direct transmission for possible diversity gains. The transmission path or the channel is modeled as a frequency non-selective Rayleigh fading in the presence additive white Gaussian noise (AWGN). The effect of path loss has been observed on cooperation for collinear arrangement with exponential decay up to four. Considering equidistant arrangement, decode-and-forward shows good performance at high signal-to-noise ratio (SNR) while amplify-and-forward is very promising for very low SNR. A selective relaying scheme called selective detect-and- forward is also presented which outperforms its fixed counterparts for a wide range of SNR.

  • 32.
    Aftab, Adnan
    et al.
    Blekinge Institute of Technology, School of Computing.
    Mufti, Muhammad Nabeel
    Blekinge Institute of Technology, School of Computing.
    Spectrum sensing through implementation of USRP22011Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Scarcity of the wireless spectrum has led to the development of new techniques for better utilization of the wireless spectrum. Demand for high data rates and better voice quality is resulting in the development of new wireless standard making wireless spectrum limited than ever. In this era of wireless communication, service providers and telecom operators are faced with a dilemma where they need a large sum of the wireless spectrum to meet the ever increasing quality of service requirements of consumers. This has led to the development of spectrum sensing techniques to find the unused spectrum in the available frequency band. The results presented in this thesis will help out in developing clear understanding of spectrum sensing techniques. Comparison of different spectrum sensing approaches. The experiments carried out using USRP2 and GNU radio will help the reader to understand the concept of underutilized frequency band and its importance in Cognitive Radios.

  • 33.
    Afzal, Nauman
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. tet10nal@student.hig.se.
    Udata, Ramakrishna
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. tet10rua@student.hig.se.
    Designing and measurement of routing module for transceiver system at 3.125GHz2014Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    This report intends to impart a good understanding of routing modules used in modern transceiver systems. The radar system at RadarBolaget AB needed to have a good routing module for its newly designed transceiver antenna. In this report, studies have been done related to two majorly used routing modules in modern electronics industry; Microwave Circulator and RF/Microwave Switch. First off, different characteristics of routing modules are discussed. After having discussed important design parameters, practical design considerations for two routing modules are presented in a profound way. Theoretical knowledge for both of these two devices is presented in the beginning, followed by their practical designs using standard simulation software like HFSS and ADS. The report concludes its findings in a way that at the end of this report, reader becomes acquainted with ample information to be able to choose the best option available among all of the discussed designs. An FET RF Switch is chosen at the end of this project to be used for transceiver system which should be able to satisfy specifications specified by RadarBolaget AB. This project was carried out by two students of Master Program in Electronics/Telecommunications at Högskolan i Gävle in collaboration with RadarBolaget AB, Gävle, Sweden.    

  • 34.
    Agelis, Sacki
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Jonsson, Magnus
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Visualizing the Potential of Reconfigurable Shuffle-Patterns in Optoelectronic Routers by the Use of MOEMS2004In: Proceedings of the IASTED International Conference Communication Systems and Networks / [ed] Salvador C.E.P., Calgary, Canada: ACTA Press, 2004, 148-154 p.Conference paper (Refereed)
    Abstract [en]

    A reconfigurable high performance multistage router architecture is presented and simulated. The router backbone network is an optical shuffle exchange network that has the power of reconfigurability through the use of micro-optical-electrical mechanical systems (MOEMS). The router is subjected to different application classes. The application classes have different characteristics in terms of symmetric/asymmetric traffic properties. We compare our reconfigurable shuffle-pattern for all three application classes for the specified router architecture.

  • 35. Aggerstam, Thomas
    et al.
    Lovqvist, Anita
    Stevens, Renaud
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Jonsson, Stefan
    Marcks von Würtemberg, Richard
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Dubois, Mardjan
    Ghisoni, Marco
    Selectively oxidized vertical-cavity surface-emitting lasers for high-speed data communication2001In: Proc. SPIE 4286, SPIE's Optoelectronics 2001, Photonics West, San Jose, US, Bellingham, WA, ETATS-UNIS: Society of Photo-Optical Instrumentation Engineers , 2001, Vol. 4286, 96- p.Conference paper (Refereed)
    Abstract [en]

    MITEL Semiconductor is developing the next generation low cost, high performance transceivers for data communication. The increasing quantity of data being transferred over the Internet demands very high capacity interconnects. A low cost, high-performance alternative is the use of parallel fiber interconnects where the light is, for example, coupled into a 12-channel fiber-ribbon. Parallel interconnects require good uniformity in order to reduce escalating costs and complexity. In this paper we report on the static and the modulation properties of 850nm multimode oxide VCSELs for use in such Gb/s transceiver system. Static power-current-voltage characteristics with good uniformity were obtained for different structures, with threshold currents down to sub-mA. A maximum small signal 3-dB bandwidth of 10 GHz and a modulation current efficiency up to 8.4 GHz/√[mA] were measured. Single channel results are presented for VCSELs operated at data rates from 2.5-10Gb/s.

  • 36.
    Agrawal, Piyush
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Signals and Systems Group.
    Ahlén, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Signals and Systems Group.
    Olofsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Signals and Systems Group.
    Gidlund, Mikael
    Long Term Channel Characterization for Energy Efficient Transmission in Industrial Environments2014In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 62, no 8, 3004-3014 p.Article in journal (Refereed)
    Abstract [en]

    One of the challenges for a successful use of wireless sensor networks in process industries is to design networks with energy efficient transmission, to increase the lifetime of the deployed network while maintaining the required latency and bit-error rate. The design of such transmission schemes depend on the radio channel characteristics of the region. This paper presents an investigation of the statistical properties of the radio channel in a typical process industry, particularly when the network is meant to be deployed for a long time duration, e. g., days, weeks, and even months. Using 17-20-h-long extensive measurement campaigns in a rolling mill and a paper mill, we highlight the non-stationarity in the environment and quantify the ability of various distributions, given in the literature, to describe the variations on the links. Finally, we analyze the design of an optimal received signal-to-noise ratio (SNR) for the deployed nodes and show that improper selection of the distribution for modeling of the variations in the channel can lead to an overuse of energy by a factor of four or even higher.

  • 37.
    Ahani, Ghafour
    et al.
    Komar University of Science and Technology, Iraq.
    Yuan, Di
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Ding, Wei
    Ranplan Wireless Network Design Ltd, England.
    On SC-FDMA Resource Allocation with Power Control2016In: 2016 IEEE 21ST INTERNATIONAL WORKSHOP ON COMPUTER AIDED MODELLING AND DESIGN OF COMMUNICATION LINKS AND NETWORKS (CAMAD), IEEE , 2016, 112-116 p.Conference paper (Refereed)
    Abstract [en]

    In this paper, single-carrier frequency division multiple accesses (SC-FDMA) is discussed. In particular, minimum stun power, subject to meeting users demand is considered. There are two channel allocation schemes, localized and interleaved. In localized scheme, a block of convective channels in the spectrum is allocated to each user. In interleaved scheme, channels will be spread out over the spectrum and will be distributed equidistantly. It has been previously assumed that when a block of channels is assigned to a user, the same amount of power will be allocated to each channel. However, the power could be used more efficiently without this assumption We show that the resulting power allocation problem can be solved in linear time and propose an optimal power allocation procedure. Next, the effect of this new power optimization procedure is investigated numerically. In the next part of paper, we prove that for the interleaved scheme, Minimum sum power problem with or without this new power optimization is polynomial solvable. Finally, we numerically compare localized and interleaved SC-FDMA with and without power optimization The results show that the localized scheme with the new power optimization yields the best performance

  • 38. Ahlfeldt, H.
    et al.
    Holm, J.
    Lindgren, S.
    Backlin, L.
    Vieider, C.
    Klinga, T.
    Kerzar, B.
    Nilsson, M.
    Svensson, M.
    Nilsson, S.
    Kjebon, Olle
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    20 GHz bandwidth of lasers flip-chip-mounted on microstructured carriers with integrated electrical waveguides1998In: Optical Communication, 1998. 24th European Conference on, 1998, Vol. 1, 205-206 p.Conference paper (Refereed)
    Abstract [en]

    A flip-chip-mounting scheme for high-speed lasers has been realised. The mounting scheme involves a microstructured silicon carrier with integrated membrane transmission lines and self-aligning solder bumps

  • 39. Ahlgren, B.
    et al.
    Ohlman, B.
    Axelsson, Erik
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture (Closed 20120101).
    Brown, Lars
    KTH, School of Information and Communication Technology (ICT).
    Subversion over OpenNetInf and CCNx2011In: Proceedings - Conference on Local Computer Networks, LCN, 2011, 1056-1063 p.Conference paper (Refereed)
    Abstract [en]

    We describe experiences and insights from adapting the Subversion version control system to use the network service of two information-centric networking (ICN) prototypes: OpenNetInf and CCNx. The evaluation is done using a local collaboration scenario, common in our own project work where a group of people meet and share documents through a Subversion repository. The measurements show a performance benefit already with two clients in some of the studied scenarios, despite being done on un-optimised research prototypes. The conclusion is that ICN clearly is beneficial also for non mass-distribution applications. It was straightforward to adapt Subversion to fetch updated files from the repository using the ICN network service. The adaptation however neglected access control which will need a different approach in ICN than an authenticated SSL tunnel. Another insight from the experiments is that care needs to be taken when implementing the heavy ICN hash and signature calculations. In the prototypes, these are done serially, but we see an opportunity for parallelisation, making use of current multi-core processors.

  • 40.
    Ahlgren, Bengt
    et al.
    RISE SICS.
    Hurtig, Per
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Abrahamsson, Henrik
    RISE SICS.
    Grinnemo, Karl-Johan
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Brunstrom, Anna
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Are MIRCC and Rate-based Congestion Control in ICN READY for Variable Link Capacity?2017In: The 13th Swedish National Computer Networking Workshop (SNCNW 2017), Halmstad University, May 29.30., 2017Conference paper (Other academic)
    Abstract [en]

    Information-centric networking (ICN) has been introduced as a potential future networking architecture. ICN promises an architecture that makes information independent from lo- cation, application, storage, and transportation. Still, it is not without challenges. Notably, there are several outstanding issues regarding congestion control: Since ICN is more or less oblivious to the location of information, it opens up for a single application flow to have several sources, something which blurs the notion of transport flows, and makes it very difficult to employ traditional end-to-end congestion control schemes in these networks. Instead, ICN networks often make use of hop-by-hop congestion control schemes. How- ever, these schemes are also tainted with problems, e.g., several of the proposed ICN congestion controls assume fixed link capacities that are known beforehand. Since this seldom is the case, this paper evaluates the consequences in terms of latency, throughput, and link usage, variable link capacities have on a hop-by-hop congestion control scheme, such as the one employed by the Multipath-aware ICN Rate-based Congestion Control (MIRCC). The evaluation was carried out in the OMNeT++ simulator, and demonstrates how seemingly small variations in link capacity significantly deterio- rate both latency and throughput, and often result in inefficient network link usage. 

  • 41.
    Ahlqvist, Johan
    Linköping University, Department of Electrical Engineering, Communication Systems.
    Evaluation of the Turbo-decoder Coprocessor on a TMS320C64x Digital Signal Processor2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    One technique that is used to reduce the errors brought upon signals, when transmitted over noisy channels, is error control coding. One type of such coding, which has a good performance, is turbo coding. In some of the TMS320C64xTM digital signal processors there is a built in coprocessor that performs turbo decoding.

    This thesis is performed on the account of Communication Developments, within Saab AB and presents an evaluation of this coprocessor. The evaluation deals with both the memory consumption as well as the data rate. The result is also compared to an implementation of turbo coding that does not use the coprocessor.

  • 42.
    Ahlström, Per
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Signalprediktering i vitt gaussiskt brus med hjälp av ett adaptivt signalanpassat filter1976Report (Other academic)
    Abstract [sv]

    Ett signalanpassat filter har ett impulssvar som är den exiterandesignalens spegelbild . Ett dylikt filter maximerar vid en viss tidpunkt signalbrusförhållandet på utgången.

    Ett adaptivt transversalfilter styrt av en gradientkännande algoritm, vilken maximerar signalbrusförhållandet på filterutgången, har studerats. Det spegelvända impulssvaret har använts som prediktion av signalen. Denna prediktion har, vid simulering gjord på dator, ej visat sig vara bättre än en klassisk prediktion med en ren summering av brusstörda upplagor av signalen. Inte ens då dylika summerade upplagor av den brusstörda signalenanvänts som insignal till filtret har signalprediktionen via filtrets impulssvar uppvisat ett lägre kvadratiskt medelfel än d en klassiska.

  • 43.
    AHMAD, FAHEEM
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    KAKKERLA, PRAMOD
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    FOCUSING OF UWB RADAR SIGNALS USING TIME REVERSAL2013Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    Focusing techniques and detection of targets is usually associated to defense and military use. However in recent past things have moved ahead. Now target detection using UWB radars is being done in many industries and corporations. Radarbolaget AB is one of them; one of their projects uses UWB radars to detect steel strips inside a furnace. This research solves a potential problem of detecting middle steel strip out of total three strip edges which can be seen by radar placed on the front. For better understanding of the reader, existing system and introductory UWB radar principles are discussed. As there can be many solutions to focusing of targets here (steel strip edge detection). Available focusing techniques have been discussed in detail along with the possible physical and simulation setups. Later in the document, detection methods have been proposed. UWB time reversed signal detection is a fairly new method and a very limited research has been done so far. PRBS sequence has been focused on in detection mechanism. Results section show that the pulse of the PRBS works better and produces more promising results rather than a repetitive signal. Time reversal methods for locating the target have been used to find the approximate location of the target. Manual distance calculations from target to the transmitter and receiver have been done. Comparison of actual distance from target to the transmitter is compared with simulation results. Different model simulation setups and their results have proved that using UWB Time reversed signals; a still or moving target can be detected with centimeter window precision.

  • 44.
    Ahmad, Nadeem
    et al.
    Blekinge Institute of Technology, School of Computing.
    Habib, M. Kashif
    Blekinge Institute of Technology, School of Computing.
    Analysis of Network Security Threats and Vulnerabilities by Development & Implementation of a Security Network Monitoring Solution2010Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Communication of confidential data over the internet is becoming more frequent every day. Individuals and organizations are sending their confidential data electronically. It is also common that hackers target these networks. In current times, protecting the data, software and hardware from viruses is, now more than ever, a need and not just a concern. What you need to know about networks these days? How security is implemented to ensure a network? How is security managed? In this paper we will try to address the above questions and give an idea of where we are now standing with the security of the network.

  • 45.
    Ahmad, Naseer
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Security Issues in Wireless Systems2009Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    ireless Communication is one of the fields of Telecommunications which is growing with the tremendous speed. With the passage of time wireless communication devices are becoming more and more common. It is not only the technology of business but now people are using it to perform their daily tasks, be it for calling, shopping, checking their emails or transfer their money. Wireless communication devices include cellular phones, cordless phones and satellite phones, smart phones like Personal Digital Assistants (PDA), two way pagers, and lots of their devices are on their way to improve this wireless world. In order to establish two way communications, a wireless link may be using radio waves or Infrared light. The Wireless communication technologies have become increasingly popular in our everyday life. The hand held devices like Personal Digital Assistants (PDA) allow the users to access calendars, mails, addresses, phone number lists and the internet. Personal digital assistants (PDA) and smart phones can store large amounts of data and connect to a broad spectrum of networks, making them as important and sensitive computing platforms as laptop PCs when it comes to an organization’s security plan. Today’s mobile devices offer many benefits to enterprises. Mobile phones, hand held computers and other wireless systems are becoming a tempting target for virus writers. Mobile devices are the new frontier for viruses, spam and other potential security threats. Most viruses, Trojans and worms have already been created that exploit vulnerabilities. With an increasing amount of information being sent through wireless channels, new threats are opening up. Viruses have been growing fast as handsets increasingly resemble small computers that connect with each other and the internet. Hackers have also discovered that many corporate wireless local area networks (WLAN) in major cities were not properly secured. Mobile phone operators say that it is only a matter of time before the wireless world is hit by the same sorts of viruses and worms that attack computer software.

  • 46.
    Ahmad, Waqas
    et al.
    Blekinge Institute of Technology, School of Engineering.
    Aslam, Muhammad Kashif
    Blekinge Institute of Technology, School of Engineering.
    An investigation of Routing Protocols in Wireless Mesh Networks (WMNs) under certain Parameters2009Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Wireless Mesh Networks (WMNs) are bringing revolutionary change in the field of wireless networking. It is a trustworthy technology in applications like broadband home networking, network management and latest transportation systems. WMNs consist of mesh routers, mesh clients and gateways. It is a special kind of wireless Ad-hoc networks. One of the issues in WMNs is resource management which includes routing and for routing there are particular routing protocols that gives better performance when checked with certain parameters. Parameters in WMNs include delay, throughput, network load etc. There are two types of routing protocols i.e. reactive protocols and proactive protocols. Three routing protocols AODV, DSR and OLSR have been tested in WMNs under certain parameters which are delay, throughput and network load. The testing of these protocols will be performed in the Optimized Network Evaluation Tool (OPNET) Modeler 14.5. The obtained results from OPNET will be displayed in this thesis in the form of graphs. This thesis will help in validating which routing protocol will give the best performance under the assumed conditions. Moreover this thesis report will help in doing more research in future in this area and help in generating new ideas in this research area that will enhance and bring new features in WMNs.

  • 47.
    ahmed, amar
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Performance and Modeling of SIP Session Setup2009Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    During the recent last years, transport of multimedia sessions, such as audio streams and video conferences, over IP has acquired a lot of attention since most of communication technologies are migrating to work over IP. However, sending media streams over IP networks has encountered some problems related to signaling issues. The ongoing research in this area has produced some solutions to this subject. Internet Engineering Task Force (IETF) has introduced Session Initiation Protocol (SIP), which has proved to be an efficient protocol for controlling sessions over IP. While a great deal of research performed in evaluating the performance of SIP and comparing it with its competent protocols such as H.323, studying the delay caused by initiating the session has acquired less attention. In this document, we have addressed the SIP session setup delay problem. In the lab, we have built up a test bed for running several SIP session scenarios. Using different models for those scenarios, we have measured session setup delays for all used models. The analysis performed for each model showed that we could propose some models to be applied for SIP session setup delay components.

  • 48.
    Ahmed, Ashraf Awadelkarim Widaa
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Towards Affordable Provisioning Strategies for Local Mobile Services in Dense Urban Areas: A Techno-economic Study2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The future mobile communication networks are expected to cope with growing local usage patterns especially in dense urban areas at more affordable deployment and operation expenses. Beyond leveraging small cell architectures and advanced radio access technologies; more radio spectrum are expected to be required to achieve the desired techno-economic targets. Therefore, the research activity has been directed towards discussing the benefits and needs for more flexible and local spectrum authorization schemes. This thesis work is meant to be a contribution to this ongoing discussion from a techno-economic perspective.

     

    In chapter three, the engineering value of the different flexible authorization options are evaluated from the perspective of established mobile network operators using the opportunity cost approach. The main results in chapter three indicate the economic incentives to deploy more small cells based on flexible spectrum authorization options are subject to the potential saving in the deployment and operation costs. Nonetheless; high engineering value can be anticipated when the density of small cells is equal or larger than the active mobile subscribers’ density.

     

    While in chapter four, the possible local business models around different flexible authorization options are investigated from the perspective of emerging actors with limited or ’no’ licensed spectrum resources. In this context, dependent or independent local business can be identified according to surrounding spectrum regulations. On possible independent local business models for those emerging actors is to exploit the different flexible spectrum authorization options to provision tailored local mobile services. Other viable dependent local business models rest with the possibility to enter into different cooperation agreements to deploy and operate dedicated local mobile infrastructure on behalf established mobile network operators.

  • 49.
    Ahmed, Ashraf Awadelkarim Widaa
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Chatzimichail, Konstantinos
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Markendahl, Jan
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Techno-economics of Green Mobile Networks Considering Backhauling2014In: European Wireless 2014; 20th European Wireless Conference; Proceedings of, Barcelona: VDE Verlag GmbH, 2014, 1-6 p.Conference paper (Refereed)
    Abstract [en]

    In this paper we consider a comparative analysis of different deployment solutions in terms of total cost of ownership (TCO) and impact of energy efficiency as a cost parameter, i.e. mobile operator's electric bill. Different deployment options for the wireless segment of the network are considered: macro only versus heterogeneous networks with femto cells to support indoor traffic demand. In addition to the wireless segment different technologies for the backhauling segment are also considered: microwave versus fiber (10G-PON). Considering different user traffic intensities in an urban area and different environments such as business and residential areas, the impact of energy consumption on the TCO has been analyzed. The scope of the paper is extended to compare different backhaul technologies considering the annual increase in the traffic demand up to year 2020. The obtained results indicate that the impact of electric bill becomes more significant over the TCO especially after year 2018. Moreover, the heterogeneous deployment strategy utilizing indoor femto-cells achieves significant savings in terms of electric bill and TCO compared to the macro only solution. However, the saving ratio varies according to the adopted backhauling technology.

  • 50.
    Ahmed, Ashraf AwadElkarim Widaa
    et al.
    Blekinge Institute of Technology, School of Engineering.
    Makki, Ahmed Hamza Ibrahim
    Blekinge Institute of Technology, School of Engineering.
    Performance Evaluation of Uplink Multiple Access Techniques in LTE Mobile Communication System2010Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    The User Equipments (UE) nowadays are able to provide various internet applications and services that raise the demand for high speed data transfer and Quality of Service (QoS). Accordingly, next generation mobile communication systems driven by these demands are expected to provide higher data rates and better link quality compared to the existing systems. Orthogonal Frequency Division Multiple Access (OFDMA) and Single Carrier Frequency Division Multiple Access (SC-FDMA) are strong multiple access candidates for the uplink of the International Mobile Telecommunications-Advanced (IMT-Advanced). These multiple access techniques in combination with other promising technologies such as multi-hops transmission and Multiple-Input-Multiple-Output (MIMO) will be utilized to reach the targeted IMT-Advanced system performance. In this thesis, OFDMA and SC-FDMA are adopted and studied in the uplink of Long Term Evolution (LTE). Two transmission scenarios are considered, namely the single hop transmission and the relay assisted transmission (two hops). In addition, a hybrid multiple access technique that combines the advantages of OFDMA and SC-FDMA in term of low Peak-to-Average Power Ratio (PAPR) and better link performance (in terms of Symbol Error Rate (SER)) has been proposed in relay assisted transmission scenario. Simulation results show that the proposed hybrid technique achieves better end-to-end link performance in comparison to the pure SC-FDMA technique and maintains the same PAPR value in access link. In addition, a lower PAPR is achieved compared to OFDMA case, which is an important merit in the uplink transmission due to the UE’s power resources constraint (limited battery power).

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