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  • 101.
    Guo, Jiabing
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Design and implementation of LTE-A and 5G kernel algorithms on SIMD vector processor2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With the wide spread of wireless technology, the time for 4G has arrived, and 5G will appear not so far in the future. However, no matter whether it is 4G or 5G, low latency is a mandatory requirement for baseband processing at base stations for modern cellular standards. In particular, in a future 5G wireless system, with massive MIMO and ultra-dense cells, the demand for low round trip latency between the mobile device and the base station requires a baseband processing delay of 1 ms. This is 10 percentage of today’s LTE-A round trip latency, while at the same time massive MIMO requires large-scale matrix computations. This is especially true for channel estimation and MIMO detection at the base station. Therefore, it is essential to ensure low latency for the user data traffic.

    In this master’s thesis, LTE/LTE-A uplink physical layer processing is examined, especially the process of channel estimation and MIMO detection. In order to analyze this processing we compare two conventional algorithms’ performance and complexity for channel estimation and MIMO detection. The key aspect which affects the algorithms’ speed is identified as the need for “massive complex matrix inversion”. A parallel coding scheme is proposed to implement a matrix inversion kernel algorithm on a single instruction multiple data stream (SIMD) vector processor.

    The major contribution of this thesis is implementation and evaluation of a parallel massive complex matrix inversion algorithm. Two aspects have been addressed: the selection of the algorithm to perform this matrix computation and the implementation of a highly parallel version of this algorithm.

  • 102.
    Hagernäs, Patrik
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    5G user satisfaction enabled by FASP: Evaluating the performance of Aspera's FASP2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With Ericsson’s goal to have optimal user experience at 5G’s 2020 release, it is very important to optimize transport protocols and techniques to manage the increasing amount of data traffic. Additionally, it will be important to manage handovers between very high speed 5G networks and older networks. Today most of the traffic is video on demand and the amount of this kind of traffic is expected to increase. Moreover, the current amount of data traffic will increase by an order of magnitude over the next few years. This thesis focuses on radio access networks and the difficulties they face in delivering high speed data traffic.

    This thesis analyzes one of the most used TCP protocols, CUBIC, as well as a new transport protocol developed by Aspera, called the Fast and Secure Protocol. Aspera’s FASP is a new transport protocol that promises full link utilization. FASP is built upon UDP and uses advanced round trip time measurements and queuing delay to detect the available bandwidth between two communicating hosts.

    This thesis project also provides methods to realize experiments to assess the limitations of transport protocols. These experiments are conducted in an environment that resembles the upcoming 5G radio access network. Results have shown that both delay and packet loss affect TCP more than we expected and that high packet loss is devastating. In contrast, Aspera’s FASP is very resistant to both delay and packet loss. These results and analysis provide a foundation upon which others can build.

  • 103.
    Hamid, Mohamed
    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.
    Björsell, Niclas
    University of Gävle, Sweden.
    Van Moer, Wendy
    Vrije Universiteit Brussel, ELEC department.
    Barbé, Kurt
    Vrije Universiteit Brussel, ELEC department.
    Slimane, Ben Slimane
    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.
    Blind spectrum sensing for cognitive radios using discriminant analysis: A novel approach2013In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 62, no 11, p. 2912-2921Article in journal (Refereed)
    Abstract [en]

    In this paper, we present a new spectrum sensing technique for cognitive radios based on discriminant analysis called spectrum discriminator. The presented technique uses the knowledge of the noise uncertainty and a probabilistic validation to overcome the limitations of the discriminant analysis. A comparative study between the proposed technique and the maximum-minimum eigenvalue detection has been performed based on two performance metrics: the probability of false alarm and the probability of detection. The spectrum discriminator has been further developed to a peel-off technique where all primary users can be detected. The performance of the spectrum discriminator and the peel-off technique has been tested on simulations and experimentally verified. The comparative study is based on simulations as well as measurements.

  • 104. Han, Q.
    et al.
    Yang, B.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Chen, C.
    Wang, X.
    Guan, X.
    Backhaul-Aware User Association and Resource Allocation for Energy-Constrained HetNets2017In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 66, no 1, p. 580-593, article id 7422839Article in journal (Refereed)
    Abstract [en]

    Growing attention has been paid to renewable-or hybrid-energy-powered heterogeneous networks (HetNets). In this paper, focusing on backhaul-aware joint user association and resource allocation for this type of HetNets, we formulate an online optimization problem to maximize the network utility reflecting proportional fairness. Since user association and resource allocation are tightly coupled not only on resource consumption of the base stations (BSs) but in the constraints of their available energy and backhaul as well, the closed-form solution is quite difficult to obtain. Thus, we solve the problem distributively by employing certain decomposition methods. Specifically, at first, by adopting the primal decomposition method, we decompose the original problem into a lower level resource-allocation problem for each BS and a higher level user-association problem. For the optimal resource allocation, we prove that a BS either assigns equal normalized resources or provides an equal long-term service rate to its served users. Then, the user-association problem is solved by the Lagrange dual decomposition method, and a completely distributed algorithm is developed. Moreover, applying results of the subgradient method, we demonstrate the convergence of the proposed distributed algorithm. Furthermore, to efficiently and reliably apply the proposed algorithm to the future wireless networks with an extremely dense BS deployment, we design a virtual user association and resource allocation scheme based on the software-defined networking architecture. Finally, numerical results validate the convergence of the proposed algorithm and the significant improvement on network utility, load balancing, and user fairness.

  • 105. Han, S. -W
    et al.
    Kim, H.
    Han, Y.
    Cioff, J. M.
    Zander, Jens
    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.
    Leung, V. C. M.
    Distributed power allocation for cooperative access in cognitive radios to guarantee QoS for cell edge primary users2013In: Proceedings of 2013 6th Joint IFIP Wireless and Mobile Networking Conference, WMNC 2013, New York: IEEE , 2013, p. 6549027-Conference paper (Refereed)
    Abstract [en]

    Cognitive radio (CR) systems have been proposed for efficient usage of spare spectrum licensed to primary systems. This leads to the issue of providing as much spectrum to CR users as possible while not degrading the quality of service (QoS) of primary users of the spectrum. This paper proposes a novel cooperation scheme between primary and CR users to guarantee QoS of primary users up to the cell edge while making the licensed spectrum available for opportunistic access by the CR users. We suggest that the primary users at the cell edge, who have poor QoS, should allow secondary users to access their spectrum, while at the same time, the secondary users would help to enhance the primary users QoS using superposition coding on the primary users transmissions. Thus the proposed method can provide a so called 'win-win strategy' by benefiting both primary and CR users. The proposed cooperative access scheme in cognitive radios solves efficiently the sum-rate maximization problem on cognitive Gaussian Multiple Access Channels (GMACs) for power allocation of primary systems that cooperates with CR systems in a distributed fashion. We solved the problem using iterative Jacobian method in a distributed manner. Numerical results show that the QoS of primary users at the cell edge is improved by the proposed cooperative access scheme.

  • 106.
    Han, Sang Wook
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Din, I.
    Young, W. B.
    Kim, H.
    A proportional fair spectrum allocation for wireless heterogeneous networks2014In: Proceedings of the International Symposium on Consumer Electronics, ISCE, 2014Conference paper (Refereed)
    Abstract [en]

    This paper proposes a cost-efficient proportional fair (PF) scheduling algorithm for heterogeneous networks. For the networks with different access cost, the scheduler assigns users to the networks to maximize the sum of logarithmic average cost-efficiency.

  • 107.
    Han, Sang Wook
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Kim, R.
    Han, Y.
    Leung, V. C. M.
    Cioffi, J. M.
    Zander, Jens
    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.
    An asynchronous distributed power allocation scheme for sum-rate maximization on cognitive GMACs2013In: Proceedings of 2013 6th Joint IFIP Wireless and Mobile Networking Conference, WMNC 2013, New York: IEEE , 2013, p. 6549031-Conference paper (Refereed)
    Abstract [en]

    This paper considers an asynchronous distributed power allocation scheme for sum-rate-maximization under cognitive Gaussian multiple access channels (GMACs), where primary users and secondary users may communicate under mutual interference with the Gaussian noise. Formulating the problem as a standard nonconvex quadratically constrained quadratic problem (QCQP) provides a simple distributed method to find a solution using iterative Jacobian method instead of using centralized schemes. A totally asynchronous distributed power allocation for sum-rate maximization on cognitive GMACs is suggested. Simulation results show that this distributed algorithm for power allocation converges to a fixed point and the solution achieves almost the same performance as exhaustive search.

  • 108.
    Hatherly, Robert
    et al.
    Department of Nuclear Medicine, Karolinska University Hospital, Stockholm, Sweden .
    Brolin, Fredrik
    Department of Nuclear Medicine, Karolinska University Hospital, Stockholm, Sweden .
    Oldner, Asa
    Department of Nuclear Medicine, Karolinska University Hospital, Stockholm, Sweden .
    Sundin, Anders
    Department of Molecular Medicine and Surgery, Karolinska Institute, Stockholm, Sweden .
    Lundblad, Henrik
    Department of Molecular Medicine and Surgery, Karolinska Institute, Stockholm, Sweden .
    Maguire Jr., Gerald Q.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Jonsson, Cathrine
    Department of Medical Physics, Karolinska University Hospital, Stockholm, Sweden.
    Jacobsson, Hans
    Department of Molecular Medicine and Surgery, Karolinska Institute, Stockholm, Sweden .
    Noz, Marilyn E.
    New York University, Department of Radiology.
    Technical Requirements for Na18F PET Bone Imaging of Patients Being Treated Using a Taylor Spatial Frame.2014In: Journal of nuclear medicine technology, ISSN 1535-5675Article in journal (Refereed)
    Abstract [en]

    Diagnosis of new bone growth in patients with compound tibia fractures or deformities treated using a Taylor spatial frame is difficult with conventional radiography because the frame obstructs the images and creates artifacts. The use of Na(18)F PET studies may help to eliminate this difficulty.

    METHODS: Patients were positioned on the pallet of a clinical PET/CT scanner and made as comfortable as possible with their legs immobilized. One bed position covering the site of the fracture, including the Taylor spatial frame, was chosen for the study. A topogram was performed, as well as diagnostic and attenuation correction CT. The patients were given 2 MBq of Na(18)F per kilogram of body weight. A 45-min list-mode acquisition was performed starting at the time of injection, followed by a 5-min static acquisition 60 min after injection. The patients were examined 6 wk after the Taylor spatial frame had been applied and again at 3 mo to assess new bone growth.

    RESULTS: A list-mode reconstruction sequence of 1 × 1,800 and 1 × 2,700 s, as well as the 5-min static scan, allowed visualization of regional bone turnover.

    CONCLUSION: With Na(18)F PET/CT, it was possible to confirm regional bone turnover as a means of visualizing bone remodeling without the interference of artifacts from the Taylor spatial frame. Furthermore, dynamic list-mode acquisition allowed different sequences to be performed, enabling, for example, visualization of tracer transport from blood to the fracture site.

  • 109.
    Hemlin Billström, Adam
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Huss, Fabian
    Video Integrity through Blockchain Technology2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The increasing capabilities of today’s smartphones enables users to live stream video directly from their mobile device. One increasing concern regarding videos found online is their authenticity and integrity. From a consumer standpoint, it is very hard to distinguish and discern whether or not a video found on online can be trusted, if it was the original version, or if has been taken out of context. This thesis will investigate a method which tries to apply video integrity to live streamed media.

    The main purpose of this thesis was to design and evaluate a proof of concept prototype which will apply data integrity while simultaneously recording videos through an Android device. Additionally, the prototype has an online verification platform which verifies the integrity of the recorded video. Blockchain is a technology with the inherent ability to store data in a chronological chained link of events: establishing an irrefutable database. Using cryptographic hashes together with blockchain: an Android device can generate cryptographic hashes of the data content from a video recording, and consequently transmit these hashes to a blockchain. The same video is deconstructed in the web client creating hashes that can subsequently be compared with the ones found in the blockchain.

    A resulting prototype system provides some of the desired functions. However, the prototype is limited in that it does not have the ability to sign the hashes produced. It has also been limited in that it does not employ HTTPS for communication, and the verification process needs to be optimized to make it usable for real applications.

  • 110.
    Hossain, Hossain Istiak
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Azari, Amin
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    DERA: Augmented random access for cellular networks with dense H2H-MTC mixed traffic2017In: 2016 IEEE Globecom Workshops, GC Wkshps 2016 - Proceedings, 2017, article id 7848874Conference paper (Refereed)
    Abstract [en]

    In addition to the Mobile Broadband (MBB) services, future cellular networks will need to cope with a range of new "Internet of things" (IoT) services. LTE-Advanced and future generation cellular technologies should support both service sets within one network in order to keep the service costs and deployment expenses low. Massive IoT services require much less bandwidth than the MBB services, but the network need to serve a massive number of devices in each cell. The IoT applications put stringent demands on the service reliability and energy efficiency, and some will require very low delay. The existing random access (RA) procedures of cellular networks are not really designed for large numbers of terminals, which may result in excessive collisions, and hence, link delay and waste of precious battery energy. The present work aims at solving this problem by proposing a novel delay-estimation based random access scheme that improves the resolution mechanism of the conventional RA procedure in order to lower delay and energy consumption. The performance evaluation results show that the proposed scheme can significantly reduce the access delay in densely deployed scenarios.

  • 111.
    Hossain, M. M. A.
    et al.
    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), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Jantti, R.
    Traffic offloading based energy saving market for cellular operators2017In: 2017 IEEE International Conference on Communications Workshops, ICC Workshops 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, p. 97-102, article id 7962640Conference paper (Refereed)
    Abstract [en]

    Larger share of total energy consumed by mobile network operators (MNOs) is wasted to ensure seamless coverage. Three to six MNOs covering the same geographical area results in even more energy waste. Division of scarce resource, i.e., spectrum into small chunks also deteriorates the overall performance. With exponential growth of the traffic and insignificant marginal revenue, it is time for the regulators and MNOs to resort to new ideas in order to reduce operational cost and devise appropriate mechanisms to ensure business as well as environmental sustainability. In this paper, we propose a double auction based energy saving market where MNOs share coverage and spectrum to save energy. In this market each MNO submits bid and asks to an independent auctioneer simultaneously. The bid is the offer to offload its total traffic to some other MNO along with releasing its own spectrum to be used by the latter. Similarly, the ask is the offer by a MNO to accept excess load along with the spectrum. The auctioneer matches the bids and asks, determines the trading price and makes the offloading decisions to minimize the total energy consumption. We show that even though the information is hidden among the MNOs, this mechanism allows the MNOs to save significant percentage of energy.

  • 112. Hossain, M. M. Aftab
    et al.
    Cavdar, Cicek
    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.
    Bjornson, Emil
    Jantti, Riku
    Energy-Efficient Load-Adaptive Massive MIMO2015In: 2015 IEEE GLOBECOM WORKSHOPS (GC WKSHPS), 2015Conference paper (Refereed)
    Abstract [en]

    Massive MIMO is a promising technique to meet the exponential growth of global mobile data traffic demand. However, contrary to the current systems, energy consumption of next generation networks is required to be load adaptive as the network load varies significantly throughout the day. In this paper, we propose a load adaptive massive MIMO system that varies the number of antennas following the daily load profile (DLP) in order to maximize the downlink energy efficiency (EE). A multi- cell system is considered where each base station (BS) is equipped with a large number of antennas to serve many single antenna users. In order to incorporate DLP, each BS is modeled as an M/G/m/m state dependent queue under the assumption that the network is dimensioned to serve a maximum number of users at the peak load. For a given number of users in a cell, the optimum number of active antennas maximizing EE is derived. The EE maximization problem is formulated in a game theoretic framework where the number of antennas to be used by a BS is determined through best response iteration. This load adaptive system achieves overall 19% higher EE compared to a baseline system where the BSs always run with the fixed number of antennas that is most energy efficient at peak load and that can be switched-off when there is no traffic.

  • 113.
    Hossain, M. M. Aftab
    et al.
    AALTO.
    Jantti, Riku
    AALTO.
    Cavdar, Cicek
    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.
    Dimensioning of PA for massive MIMO system with load adaptive number of antennas2014In: Globecom Workshops (GC Wkshps), 2014, 2014, p. 1102-1108Conference paper (Refereed)
    Abstract [en]

    This paper takes into consideration the non-ideal efficiency characteristics of realistic power amplifiers (PAs) along with the daily traffic profile in order to investigate the impact of power amplifier dimensioning on the energy efficiency of load adaptive massive MIMO system. A multicellular system has been considered where each base station (BS) is equipped with large number of antennas to serve many single antenna users. For a given number of users in a cell, the optimum number of active antennas maximizing energy efficiency (EE) has been derived where total BS downlink power is assumed to be fixed. Under the same assumption, the power amplifiers have been dimensioned in a way that maximize network energy efficiency not only for a for a single time snapshot but over twenty four hours of operation while considering dynamic efficiency characteristics of the PAs. In order to incorporate this daily load profile, each BS has been modeled as an M/G/c/c state dependent queue under the assumption that the network is dimensioned to serve a maximum number of users at a time corresponding to 100% cell traffic load. This load adaptive system along with the optimized PA dimensioning achieves 30% higher energy efficinecy compared to a base line system where the BSs always run with a fixed number of active antennas which are most energy efficient while serving 100% traffic load.

  • 114.
    Hossain, Md. Iqbal
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Hossain, Md. Iqbal
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Dynamic scaling of a web-based application in a Cloud Architecture2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With the constant growth of internet applications, such as social networks, online media, various online communities, and mobile applications, website user traffic has grown, is very dynamic, and is oftentimes unpredictable. These unpredictable natures of the traffic have led to many new and unique challenges which must be addressed by solution architects, application developers, and technology researchers. All of these actors must continually innovate to create new attractive application and new system architectures to support the users of these new applications. In addition, increased traffic increases the demands for resources, while users demand even faster response times, despite the ever-growing datasets underlying many of these new applications. Several concepts and best practices have been introduced to build highly scalable applications by exploiting cloud computing. As no one who expect to be or remain a leader in business today can afford to ignore cloud computing.

    Cloud computing has emerged as a platform upon which innovation, flexibility, availability, and faster time-to-market can be supported by new small and medium sized enterprises. Cloud computing is enabling these businesses to create massively scalable applications, some of which handle tens of millions of active users daily. This thesis concerns the design, implementation, demonstration, and evaluation of a highly scalable cloud based architectures designed for high performance and rapid evolution for new businesses, such as Ifoodbag AB, in order to meet the requirement for their web based application. This thesis examines how to scale resources both up and down dynamically, since there is no reason to allocate more or less resources than actually needed. Apart from implementing and testing the proposed design, this thesis presents several guidelines, best practices and recommendations for optimizing auto scaling process including cost analysis. Test results and analysis presented in this thesis, clearly shows the proposed architecture model is strongly capable of supporting high demand applications, provides greater flexibility and enables rapid market share growth for new businesses, without their need to investing in an expensive infrastructure.

  • 115.
    Hossain, Mohammad Istiak
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Designing Efficient Access Control to Comply Massive-Multiservice IoT over Cellular Networks2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Internet of Things (IoT) has come in reality to improve our living quality. Automation is embraced in all the possible business verticals that have diverse communication needs ranged from static devices’ sporadic transmission to mobile devices’ every minute transmission. Despite, there are many technologies available today to support IoT services; cellular systems can play a vital role for IoT services, like wearables, vehicular, and industrial IoT, rollout which have either mobility or security concern. 

    IoT services generated traffic are foreseen as a sporadic-bursty traffic. As the cellular networks are designed to serve continuous data traffic, the existing system’s access control mechanism cannot efficiently conform to the burstiness of traffic. This limits the scope of the network scalability in terms of simultaneous serving devices’ capacity. Also, this bursty pattern can extensively increase the rate of network’s congestion incident. In this thesis, we focus on these underlying challenges to support a large number of heterogeneous IoT services with existing services over the same radio network. An important question for supporting IoT services over cellular networks is how detrimental are the effects of IoT services on other services of cellular networks. This dissertation seeks to answer this with quantitative results to indicate the real constraints of existing networks.

    An important conclusion is that existing cellular system is incompetent to support the bursty arrival of massive IoT devices in terms of radio networks’ access control plane’s scalability. Therefore, this dissertation presents solutions to overcome the identified limitations of access control planes. To improve the performance of the access control plane, we incorporate a vertical core network controlled group management scheme that can assure the operator’s granular control over capillary gateways. Besides, this introduces a unique handover opportunity between cellular and capillary network vertices. Then, we present a simple but efficient initial access mechanism to overcome the initial access collision at the very early stage. Finally, we show the impact of access collision and retransmission on the initial access resource dimensioning.We present a practical traffic model that is realistic for the traffic scenario for mixed-traffic. Our presented results and analysis depict the trade-offs between access rate, retransmission and resource allocation over time and frequency.Our results reveal that with proposed schemes of the cellular system’s access control plane can be scalable and resilient to accommodate a large number of IoT devices without incurring extra delay or need of resources to the system.

  • 116.
    Hossain, Mohammad Istiak
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Azari, Amin
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Markendahl, Jan
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Enhanced Random Access:: Initial Access Load Balance in HighlyDense LTE-A Networks for Multiservice (H2H-MTC) Traffic2017In: 2017 IEEE International Conference on Communications, IEEE, 2017, p. 1-7, article id 7996622Conference paper (Refereed)
    Abstract [en]

    The Random Access (RA) procedure in existing cellular networks is not capable of functioning properly during high access load conditions. For this purpose, overload control mechanisms are needed. Most proposed mechanisms in the literature offer a tradeoff between access rate and experienced delays. However, when the maximal tolerated delay and the energy spent on retransmissions are tightly bounded, the very high access rate, targeted for 5G systems, cannot be achieved. For these situations, we propose the Delay Estimation based RA (DERA)-scheme that has the potential to meet very stringent reliability requirements, even in high access load conditions. The present work shows that this goal can be achieved only at the cost of limited additional complexity. Furthermore, we also study the optimal switchover point at which the proposed scheme moves from low-load to the high-load phase. The derived tool can also be used along with other proposed RA overload control schemes, e.g.when to invoke access class barring. The performance evaluation results show that the novel DERA scheme can significantly improve the control channels’ resource utilization along with the success rate in dense deployment scenarios.

  • 117.
    Hossain, Mohammad Istiak
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Islam, Raihan Ul
    Luleå University of Technology.
    Azari, Amin
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Andersson, Karl
    Luleå University of Technology.
    Early Data Transmit in Cellular-IoT: A Supervised Learning Approach to Optimized Resource Pool Allocation2020In: Article in journal (Refereed)
    Abstract [en]

    3GPP introduced Early Data Transmit (EDT) protocol in release-15 to address Internet of things (IoT) services signaling cost and connection delay due to RRC connectivity procedure. EDT enables data transmission in MSG3 wherein traditional RACH procedure, a collision is realized at MSG3 reception. Traditional preventive approach (access class barring) may control the device access rate, but that does not always adequate to solve hidden collision due to the receiver’s limitation and devices power control mechanism. The present work aims at solving the problem by allocating extra resources pool for potential collided devices. The allocated resource of the pool is optimized based on an artificial neural network (ANN) based learning algorithm. The performance evaluation result shows that the learning-based resource allocation radically increases the data transmission success rate with EDT.

  • 118.
    Hossain, Mohammad Istiak
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Laya, Andres
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Militano, Francesco
    Ericsson Research.
    Iraji, Sassan
    Aalto University..
    Reducing Signaling Overload:: Flexible Capillary Admission Control for Dense MTC over LTE Networks2015Conference paper (Refereed)
    Abstract [en]

    The increasing adoption of Machine-Type Communication (MTC) applications on existing LongTerm Evolution (LTE) brings new challenges for additional signaling mechanism and system capacity.MTC is related to a high number of devices; which represents a challenge when performing control and signaling procedures required for getting resource grant since these processes are inefficient compared to the actual resource usage for small data transmissions.Solutions based on device grouping propose a static grouping approach, which does not perform well in low load scenario. This paper introduces the notion of a flexible admission/connection that can give granular group device control to Core network. With the proposed approach devices can be grouped for a certain period under supervision and control of a gateway and they can be ungrouped when there is no need for grouping them together. In this way, a finer control can be achieved on prioritizing certain services and load balancing. Our simulation results demonstrate significant signaling reduction by using this simple scheme compared to conventional connection procedure.

  • 119.
    Huq, Rachaen
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Moreno, Kevin
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Zhu, Hui
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Zhang, Jue
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Ohlsson, Oscar
    Ericsson Research.
    Hossain, Mohammad Istiak
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    On the Benefits of Clustered Capillary Networks for Congestion Control in Machine Type Communications over LTE2015Conference paper (Refereed)
    Abstract [en]

    One of the significant complexities that MachineType Communications (MTC) is expected to bring about is congestion. One promising conceptual approach in the literature to reduce congestion is clustering or grouping based solutions.Designing group-based solutions highly depend on particular cases, and it is challenging to come up with a universal solution.This paper is based on a project designed to address a grouping based congestion control technique in a particular MTC application scenario using the Capillary Networks approach from an experimental point of view. In this paper, an MTC congestion scene is generated inside a network-simulation environment in a defined “parking lot scenario” during a busy hour, where a huge number of cars and parking space sensors will try to connect to an LTE node in a congestive fashion. Based on the impact of this congestion on the node, the simulation results were analyzed to come up with a reasonable cluster size, a comparison of technologies to communicate within a group, and the benefits and tradeoffs due to clustering and Capillary Network-based solutions.

  • 120. Hwang, T.
    et al.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Park, H.
    Kwon, Y.
    Himayat, N.
    Green Radio2015In: Green Communications: Principles, Concepts and Practice, Wiley-Blackwell, 2015, p. 119-134Chapter in book (Other academic)
    Abstract [en]

    This chapter gives a comprehensive introduction to state-of-the-art energy-efficient communications, focusing on the physical (PHY) and medium access control (MAC) layers of wireless communication systems. The PHY layer consists of RF circuits, modulation, power control, and channel coding units, and so on and delivers data transmission as reliably as possible. The MAC layer ensures network-wide efficient resource management while maintaining quality of service (QoS) requirements of individual users. As wireless is a shared communication medium, with wireless communications, device energy consumption is not only affected by the designs of different layers of the point-to-point communicating link but also by the interactions of all links in the network. A system approach is therefore necessary for energy-efficient wireless communications system design. The focus of this chapter is on wireless system design, analysis, and optimization emphasizing energy efficiency enhancement while meeting given performance requirements. Since the design of all protocol layers impact energy consumption, this chapter introduces cross-layer energy-efficient techniques to reduce redundant message transfers and the associated energy consumption. Cross-layer techniques exploit interactions between different layers to significantly improve energy efficiency and adaptability to service, traffic, and environment dynamics.

  • 121.
    Höglund, Rikard
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Lightweight Message Authentication for the Internet of Things2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    During the last decade, the number of devices capable of connecting to the Internet has grown enormously. The Internet of Things describes a scenario where Internet connected devices are ubiquitous and even the smallest device has a connection to the Internet. Many of these devices will be running on constrained platforms with limited power and computing resources. Implementing protocols that are both secure and resource efficient is challenging. Current protocols have generally been designed for mains powered devices; hence, they are not optimized for running on constrained devices. The Constrained Application Protocol (CoAP) is a protocol for network communication specifically designed for constrained devices. This thesis project examines CoAP and presents an extension that adds authentication in a way that is suitable for constrained devices, with respect to minimizing resource use. The proposed solution has been compared and contrasted with other alternatives for authentication, particularly those alternatives used with CoAP. It has also been implemented in code and experimentally evaluated with regards to performance versus vanilla CoAP.

    The main goal of this project is to implement a lightweight authentication extension for CoAP to be deployed and evaluated on constrained devices. This extension, called Short Message Authentication ChecK (SMACK), can be used on devices that require a method for secure authentication of messages while using only limited power. The main goal of the extension is to protect against battery exhaustion and denial of sleep attacks. Other benefits are that the extension adds no additional overhead when compared with the packet structure described in the latest CoAP specification. Minimizing overhead is important since some constrained networks may only support low bandwidth communication.

  • 122.
    Jakobsson, Per-Johan Simon
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Cloud-Based Alerting System for IP-Telephony: A prototype development2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    An increasing number of people in Sweden are having problems with their hearing ability. The three major tools to aid hearing-impaired and deaf individuals are: hearing aids, special telephony, and alerting systems. Both hearing aids and telephony have seen a huge technical development. Hearing aids have gone from huge ponderous devices to small delicate in-ear devices. Simple text telephones have evolved into total conversation telephones with audio, video, and text all operating in real time. Although smart lamps and other alerting services not specifically made for hearing-impaired individuals do exist, the development of alerting system is unsatisfactory. The gap in technology is a huge problem and integration between modern products and alerting systems is getting harder. This thesis explores how to close this gap. The result of this thesis project is a prototype that provides the missing technological link between an alerting systems and modern smart devices. An eventual product should support all kinds of services, but the prototype is limited to solving the problem of connecting an alerting system to a modern total conversation telephones. The prototype was evaluated and based on the evaluation data a timeline was created. An overall positive response towards the product exists and the timeline had adding more third party services (such as Skype and FaceTime) as a high priority. The complete timeline as well as adding Signal Initiation Protocol support is left as future work.

  • 123.
    Jalalinia, Shabnam S.
    et al.
    KTH, School of Information and Communication Technology (ICT).
    Cavdar, Cicek
    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.
    Green and resilient design of telecom networks with shared backup resources2017In: OPTICAL SWITCHING AND NETWORKING, ISSN 1573-4277, Vol. 23, p. 97-107Article in journal (Refereed)
    Abstract [en]

    Backbone telecommunication network infrastructures are deployed with redundant resources taking into account the backup capacity for protection in order to be resilient against link failures, and serving extremely large amount of data transmission resulting in increasing power consumption. In this study, the interplay between green and resilient network design, and flow routing mechanisms is analyzed. We propose Mixed Integer Linear Programming (MILP) models to obtain optimum solutions under various objectives: Minimizing consumption of (I) Capacity, (II) Capacity+ Power, and (III) Power. Two different shared backup protection (SBP) schemes (1) SBP-ind (failure independent) and (2) SBP-dep (failure dependent) are compared with dedicated path protection (DPP). It is assumed that network links utilized by only backup paths can be put into sleep mode. It is observed that when power consumption is minimized, the backup sharing decreases in SBP and, in the extreme case, it behaves similar to DPP. The models are generalized and valid for both IP traffic flow routing and lightpath routing. It is shown that for a sample network topology, to save e.g., 32.33% power, capacity consumption increases significantly, e.g., in SBP-ind up to 127.53%. In order to achieve a compromise between power and capacity consumption, we propose a multi-objective approach. All the MILP models are run and results are presented for a small scale European network topology as well as a larger scale sample US network topology. For larger problem instances ILP solutions are not scalable. Therefore, a novel energy efficient and survivable routing and network design algorithm, called energy-aware shared path protection (EASPP), addressing the trade-off caused by conflicting objectives of green and resilient network planning is proposed. Moreover this study presents a complete picture of various survivability mechanisms when power consumption is minimized together with the capacity consumption.

  • 124.
    Jalalinia, Shabnam Sadat
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Çavdar, Çiçek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Interplay between energy efficiency and survivable network planning with shared backup resources2015In: Proceedings of 2015 7th International Workshop on Reliable Networks Design and Modeling, RNDM 2015, Institute of Electrical and Electronics Engineers (IEEE), 2015, p. 288-294Conference paper (Refereed)
    Abstract [en]

    Backbone network infrastructures are deployed with redundant resources taking into account the backup capacity for protection in order to be resilient against link failures, serving extremely large amount of data transmission. This goes together with increasing power consumption of backbone networks. In this study the impact of green network design and flow routing mechanisms on different protection schemes is analyzed thoroughly by proposing models to obtain optimum solutions under various objectives: Minimizing consumption of (I) Capacity, (II) Capacity+Energy, and (III) Energy. Two different shared backup protection (SBP) schemes (1) SBP-ind (failure independent) and (2) SBP-dep (failure dependent) are compared with dedicated path protection (DPP). It is assumed that network links utilized by only backup paths can be put into sleep mode. It can be observed that when energy consumption is minimized, the backup sharing decreases in SBP and, in the extreme case, it behaves similar to DPP. The models are generalized and valid for both IP traffic flow routing and lightpath routing. It is shown that for a sample network topology, to save e.g., 32.33% power, capacity consumption increases significantly e.g., in SBP-ind up to 127.53%. In order to achieve a good compromise between power and capacity consumption we propose a multi-objective approach. Moreover this study presents a complete picture of various survivability mechanisms when power consumption is minimized together with the capacity consumption.

  • 125.
    Janek Strååt, Sara
    et al.
    Karolinska Institutet and Stockholm University.
    Andreassen, Björn
    Karolinska Institutet and Stockholm University.
    Johansson, Cathrine
    Karolinska University Hospital Solna, Sweden.
    Noz, Marilyn E.
    New York University, Department of Radiology.
    Maguire Jr., Gerald Q.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Näfstadius, Peder
    Karolinska University Hospital.
    Näslund, Ingemar
    Karolinska Institutet.
    Schoenahl, Frederic
    University Hospital of Geneva, Geneva, Switzerland .
    Brahme, Anders
    Karolinska Institute.
    Clinical application of in vivo treatment delivery verification based on PET/CT imaging of positron activity induced at high energy photon therapy2013In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 58, no 16, p. 5541-5553Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to investigate in vivo verification of radiation treatment with high energy photon beams using PET/CT to image the induced positron activity. The measurements of the positron activation induced in a preoperative rectal cancer patient and a prostate cancer patient following 50 MV photon treatments are presented. A total dose of 5 and 8 Gy, respectively, were delivered to the tumors. Imaging was performed with a 64-slice PET/CT scanner for 30 min, starting 7 min after the end of the treatment. The CT volume from the PET/CT and the treatment planning CT were coregistered by matching anatomical reference points in the patient. The treatment delivery was imaged in vivo based on the distribution of the induced positron emitters produced by photonuclear reactions in tissue mapped on to the associated dose distribution of the treatment plan. The results showed that spatial distribution of induced activity in both patients agreed well with the delivered beam portals of the treatment plans in the entrance subcutaneous fat regions but less so in blood and oxygen rich soft tissues. For the preoperative rectal cancer patient however, a 2 +/- (0.5) cm misalignment was observed in the cranial-caudal direction of the patient between the induced activity distribution and treatment plan, indicating a beam patient setup error. No misalignment of this kind was seen in the prostate cancer patient. However, due to a fast patient setup error in the PET/CT scanner a slight mis-position of the patient in the PET/CT was observed in all three planes, resulting in a deformed activity distribution compared to the treatment plan. The present study indicates that the induced positron emitters by high energy photon beams can be measured quite accurately using PET imaging of subcutaneous fat to allow portal verification of the delivered treatment beams. Measurement of the induced activity in the patient 7 min after receiving 5 Gy involved count rates which were about 20 times lower than that of a patient undergoing standard F-18-FDG treatment. When using a combination of short lived nuclides such as O-15 (half-life: 2 min) and C-11 (half-life: 20 min) with low activity it is not optimal to use clinical reconstruction protocols. Thus, it might be desirable to further optimize reconstruction parameters as well as to address hardware improvements in realizing in vivo treatment verification with PET/CT in the future. A significant improvement with regard to O-15 imaging could also be expected by having the PET/CT unit located close to the radiation treatment room.

  • 126.
    Jedenmalm, Anneli
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Lund University, Sweden.
    Nilsson, Fritjof
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Noz, Marilyn E.
    New York University, Department of Radiology.
    Green, Douglas D.
    Loma Linda University, Orthopaedic Research Center.
    Gedde, Ulf W.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Clarke, Ian C.
    Loma Linda University, Orthopaedic Research Center.
    Stark, Andreas
    Karolinska Institute, Department of Molecular Medicine and Surgery.
    Maguire Jr., Gerald Q.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Zeleznik, Michael P.
    Saya Systems Inc., Salt Lake City, UT, USA.
    Olivecrona, Henrik
    Karolinska Institute, Department of Molecular Medicine and Surgery.
    Validation of a 3D CT method for measurement of linear wear of acetabular cups: A hip simulator study2011In: Acta Orthopaedica, ISSN 1745-3674, E-ISSN 1745-3682, Vol. 82, no 1, p. 35-41Article in journal (Refereed)
    Abstract [en]

    Material and methods Ultra-high molecular weight polyethylene cups with a titanium mesh molded on the outside were subjected to wear using a hip simulator. Before and after wear, they were (1) imaged with a CT scanner using a phantom model device, (2) measured using a coordinate measurement machine (CMM), and (3) weighed. CMM was used as the reference method for measurement of femoral head penetration into the cup and for comparison with CT, and gravimetric measurements were used as a reference for both CT and CMM. Femoral head penetration and wear vector angle were studied. The head diameters were also measured with both CMM and CT. The repeatability of the method proposed was evaluated with two repeated measurements using different positions of the phantom in the CT scanner. Results The accuracy of the 3D CT method for evaluation of linear wear was 0.51 mm and the repeatability was 0.39 mm. Repeatability for wear vector angle was 17 degrees A degrees. Interpretation This study of metal-meshed hip-simulated acetabular cups shows that CT has the capacity for reliable measurement of linear wear of acetabular cups at a clinically relevant level of accuracy.

  • 127.
    Jin, Youbei
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Integration and assessment of streaming video content and API development into a spaced repetition service2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    There are a lot of spaced repetition system based online learning services available nowadays, but none of them are popular or widely accepted as a good means for studying. The problem of these services is, instead of exploiting and utilizing the possibility of modern technology, they simply brought this old school learning method to the web as an application with exactly the same experience as one could have with textbooks and flash cards. This master’s thesis project concerns Sharplet, a spaced repetition system based web service, who is trying to stand out by offering some features that none of the other comparable services have. One of these features is the integration of YouTube video clips, so that in addition to text and pictures, study materials may now include both audio and video material.

    This thesis begins by reviews spaced repetition systems in general, and then focuses on some of the existing services and how to provide a better service. Next the thesis describes the design, implementation, and evaluation of a new service that includes both audio and video content. The main practical result of this master’s thesis project is a working prototype audio and video enabled spaced repetition based service. Unfortunately, the actual performance of this prototype is unacceptable, hence there is a need to improve its performance before it can be integrated with the production spaced repetition system.

  • 128.
    Johansson, Carl
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Kavosi, Soren
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Automating Interactions with Web Services: NFC based attendance software in Java2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Today we use an obsolete way of handling information regarding which student and/or teacher is attending which class/lab/seminar, attendance is written down on a piece of paper and collected so that an administrator can manually enter this information to some data processing system.

    This method is far from optimal and demands a lot of time and resources from administrators, teachers, and students. Correct gathering of attendance is important since it is required for specific parts of some courses. We propose to automate the collection of this attendance data, thus enabling students and teachers to simply swipe their NFC-enabled KTH access card in order to enter their name on an attendance list. This will be achieved by creating an application that adds a student to an attendance list by reading information using a NFC/RFID reader and mapping the card’s UID to a KTHID (a locally unique identifier used within the university) using a database. The resulting attendance list should be formatted in such a fashion that it can easily be uploaded to systems such as KTH Social and Daisy. Ideally these systems will be extended so that instructors/teachers can use this attendance list to automatically create the appropriate entries in these systems to record the student’s participation in the indicated activity – in the process avoiding a lot of manual labor and improving the accuracy of the process.

    An additional problem is that there is currently no unified system that connects the KTH access card database (BRAVIDA) to the KTH LDAP database (which stores information about KTH students, faculty, and staff). This means that each student’s access card UID must manually be added to a database together with the student’s KTHID. However, once this database entry has been made, we can then map from a card number to a KTHID (or the reverse).

    The purpose behind and expected result of this thesis is a functional prototype of an application that creates an attendance list by reading data from the student or teacher’s access cards using a NFC reader. This will hopefully stimulate further digitalization in KTH and also encourage more courses to utilize such access card based attendance lists. The result should be less manual effort by students, faculty, and staff, as well as more accurate and timely filing of attendance information for courses.

  • 129.
    Johansson, Victor
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Enhancing user satisfaction in 5G networks using Network Coding2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Network data rates are growing rapidly. The data rates provided to the customers by their network providers vary from Mbps to Gbps. However, rarely do users get the promised peak throughput.

    In cellular networks, network conditions change based on obstacles, weather conditions between the client and the base stations, and even the movement of objects and people. As a result of the changes in the radio link, the data transfer rate can change rapidly, hence devices needs to adjust their communications based on the currently available data rate.

    The Transmission Control Protocol (TCP) is widely used for reliable data transfer over networks. However, TCP was initially designed when link data rates were much lower than the link data rates commonly available today. As a result, TCP does not perform well at high data rates, despite some of the changes that have been made to the protocol to support high data rate links. Moreover, TCP has problems adapting to large changes in link bandwidth (not caused by congestion), resulting in a lower average throughput than the link could potentially deliver.

    This thesis evaluates two different versions of the TCP protocol (e.g., TCP Reno and Cubic TCP) and proposes a network coding scheme to enhance users’ experience when communicating over unstable radio links. The performance of the two TCP protocols and Random Linear Network Coding (RLNC) scheme were measured in an emulated network environment. The results of these measurements were analyzed and evaluated. The analysis shows that RLNC can provide a higher throughput than TCP over a network with high packet loss. However, RLNC is a UDP based solution and does not implement congestion control algorithms or reliability. A new solution is proposed that increases reliability and implements network adaptation in RLNC solutions.

    The results obtained in this thesis can be used to develop a new protocol to increases the quality of users’ experience in high loss networks.

  • 130.
    Kabir, Sanzida
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Säkerhetsstandard för ett mjukvarubaserat säkerhetselement2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Researchers today anticipate that in the near future, the majority of the owners of a smartphone will use it as a wallet, i.e. for contactless payment. The technology that enables contactless payment today is “Near Field Communication” (NFC), which is increasingly embedded in smartphones. Applications like mobile payment between a phone and a terminal use NFC. With Mobile payment the user’s credit and banking information gets saved and it’s extremely important for a user that the saved data doesn’t fall into the wrong hands. How should then a user of an NFC equipped device ensure that end-to-end security is strong enough when they use NFC technology? Can user feel safe enough to keep their private documents on the phone without getting “robbed”?

    NFC uses a security element “Secure Element” (SE) that offers the user safety for their mobile purchases but also in other applications such as transportation tickets. The security element comes in three forms: SD card based, SIM card based or embedded in the smartphone. Over time, the technology behind the secure element is further developed and a new phenomenon has emerged, a new type of secure element. The new technology is an application based secure element: “Software Emulation Card” (Soft-SE), which offers security without a physical SE This thesis will deal with the Secure Element’s area to see if the Soft-SE are so confident that we can count it as an option when we do our mobile purchases in the store. A number of threats and attacks that an SE or generally an NFC device can be exposed to will be mentioned and some will also be described and some possible threats and attacks against Soft-SE. In addition, a few pros and cons of applying Soft-SE will be discussed. The analysis is based on how a user can get more out of the existing SE instead of applying the Soft-SE. Based on the facts, pros and cons, and the analysis that has been treated, it has been concluded that the Soft-SE is not a more secure alternative than the SE that is already used by NFC phones. Since Soft-SE is still new, it has not yet developed to protect themselves against the possible attacks that they may be exposed to. It is strongly recommended that users of Google Wallet adhere to the Secure Element that the smartphone use instead of applying Soft-SE.

  • 131.
    Kamel, Mozhdeh
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Extending the precision time protocol to a metropolitan area network: Synchronizing radio base stations2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    When building various types of wide area cellular radio networks there is a need to synchronize all of the base stations within a given system. Today this is typically done by attaching a highly accurate clock to each radio base station. A GPS radio receiver is commonly used as such a clock. This thesis explores the use of the Precision Time Protocol (PTP) to provide synchronization of radio base stations, rather than the current practice of using GPS radio receivers.

    Advantages of utilizing PTP rather than a GPS radio receiver include the ability to easily locate radio base stations (without the need for connecting the GPS radio receiver to an antenna that has line of sight to a sufficient number of GPS satellites); the system is not vulnerable to interference with or jamming of GPS radio signals; the system is not vulnerable to spoofing of GPS radio signals, and because the new generations of radio base stations are connected to a packet based backhaul link – the system can potentially utilize the existing packet network interface (thus avoiding the need for a serial interface to the GPS receiver and a pulse per second input).

    At the start of this thesis project it was not known what the limits of PTP are (in terms of utilizing PTP together with radio base stations). Thus it was not clear whether PTP could be extended to much longer distances than it had originally been designed for.<p> This thesis shows that PTP can be used as an accurate timing source to synchronize base stations in networks with up to four switches between the PTP grandmaster and any PTP slave.<p> This project was performed in the Common Transport Feature department at Ericsson.

  • 132.
    Kanthla, Arjun Reddy
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Network Performance Improvement for Cloud Computing using Jumbo Frames2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The surge in the cloud computing is due to its cost effective benefits and the rapid scalability of computing resources, and the crux of this is virtualization.  Virtualization technology enables a single physical machine to be shared by multiple operating systems. This increases the eciency of the hardware, hence decreases the cost of cloud computing. However, as the load in the guest operating system increases, at some point the physical resources cannot support all the applications efficiently. Input and output services, especially network applications, must share the same total bandwidth and this sharing can be negatively affected by virtualization overheads. Network packets may undergo additional processing and have to wait until the virtual machine is scheduled by the underlying hypervisor before reaching the final service application, such as a web server.In a virtualized environment it is not the load (due to the processing of the user data) but the network overhead, that is the major problem. Modern network interface cards have enhanced network virtualization by handling IP packets more intelligently through TCP segmentation offload, interrupt coalescence, and other virtualization specific hardware.

    Jumbo frames have long been proposed for their advantages in traditional environment. They increase network throughput and decrease CPU utilization.  Jumbo frames can better exploit Gigabit Ethernet and offer great enhancements to the virtualized environment by utilizing the bandwidth more effectively while lowering processor overhead. This thesis shows a network performance improvement of 4.7% in a Xen virtualized environment by using jumbo frames.  Additionally the thesis examines TCP's performance in Xen and compares Xen with the same operations running on a native Linux system.

  • 133.
    Karadogan, Günay Mert
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Evaluating WebSocket and WebRTC in the Context of a Mobile Internet of Things Gateway2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis project explores two well-known real-time web technologies: WebSocket and WebRTC. It explores the use of a mobile phone as a gateway to connect wireless devices with short range of radio links to the Internet in order to foster an Internet of Things (IoT).

    This thesis project aims to solve the problem of how to collect real-time data from an IoT device, using the Earl toolkit. With this thesis project an Earl device is able to send real-time data to Internet connected devices and to other Earl devices via a mobile phone acting as a gateway. This thesis project facilitates the use of Earl in design projects for IoT devices.

    IoT enables communication with many different kinds of “things” such as cars, fridges, refrigerators, light bulbs, etc. The benefits of IoT range from financial savings due to saving energy to monitoring the heart activity of a patient with heart problems. There are many approaches to connect devices in order to create an IoT. One of these approaches is to use a mobile phone as a gateway, i.e., to act as a router, between IoT and the Internet.

    The WebSocket protocol provides efficient communication sessions between web servers and clients by reducing communication overhead. The WebRTC project aims to provide standards for real-time communications technology. WebRTC is important because it is the first real-time communications standard which is being built into browsers.

    This thesis evaluates the benefits which these two protocols offer when using a mobile phone as a gateway between an IoT and Internet. This thesis project implemented several test beds, collected data concerning the scalability of the protocols and the latency of traffic passing through the gateway, and presents a numerical analysis of the measurement results. Moreover, an LED module was built as a peripheral for an Earl device. The conclusion of the thesis is that WebSocket and WebRTC can be utilized to connect IoT devices to Internet.

  • 134.
    Karim, Rafid
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Al-Fakhri, Haidara
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Smart Door Lock: A first prototype of a networked power lock controller with an NFC interface2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Most major cell phone manufacturers have been releasing cell phones equipped with Near Field Communication (NFC). At the same time there is also increasing use of mobile payments and user verification with the use of the NFC technology. These trends indicate both the increasing popularity and great potential for increased use of NFC in today’s society. As a result NFC has a huge potential to simplify our everyday tasks, ranging from paying for items to accessing our office or home.

    In this context we will focus on using NFC together with a Power over Ethernet (PoE) powered circuit board and NFC reader to realize a simple system for granting access to open a locked door. One of the purposes of this realization is to explore what services can be realized when such a system is connected to the home/building network and connected to the Internet. A second purpose is to learn how to use network attached devices, as the concept of the Internet of Things is considered by many to be a driving force in the next generation Internet. This project uses very in expensive and low power hardware, as the number of devices is potentially very large and thus in order to minimize the technology’s impact on the environment we must consider how to minimize the power used – while maintaining the desired user functionality.

    This bachelor’s thesis project made it possible for a PoE powered circuit board containing a MSP430 microcontroller to work along with a NFC reader, which was connected through the Serial Peripheral Interface (SPI).

    We hope that the end result of this project will lead to a simpler life by exploiting this increasingly ubiquitous technology. For example, a homeowner could send a one-time key to a repair person who is coming to fix their sink. Similarly a homeowner could send a key to their neighbor which is valid for two weeks so that their neighbor could come into their home to water the plants while they are away on vacation. Another example is lending your apartment key to a friend while you are out of town.

  • 135.
    Kathirvel, Anitha
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Madan, Siddharth
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Efficient Privacy Preserving Key Management for Public Cloud Networks2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Most applications and documents are stored in a public cloud for storage and management purposes in a cloud computing environment. The major advantages of storing applications and documents in public cloud are lower cost through use of shared computing resources and no upfront infrastructure costs. However, in this case the management of data and other services is insecure. Therefore, security is a major problem in a public cloud as the cloud and the network are open to many other users. In order to provide security, it is necessary for data owners to store their data in the public cloud in a secure way and to use an appropriate access control scheme.

    Designing a computation and communication efficient key management scheme to selectively share documents based on fine-grained attribute-based access control policies in a public cloud is a challenging task. There are many existing approaches that encrypt documents prior to storage in the public cloud: These approaches use different keys and a public key cryptographic system to implement attribute-based encryption and/or proxy re-encryption. However, these approaches do not efficiently handle users joining and leaving the system when identity attributes and policies change. Moreover, these approaches require keeping multiple encrypted copies of the same documents, which has a high computational cost or incurs unnecessary storage costs. Therefore, this project focused on the design and development of an efficient key management scheme to allow the data owner to store data in a cloud service in a secure way. Additionally, the proposed approach enables cloud users to access the data stored in a cloud in a secure way.

    Many researchers have proposed key management schemes for wired and wireless networks. All of these existing key management schemes differ from the key management schemes proposed in this thesis. First, the key management scheme proposed in this thesis increases access level security. Second, the proposed key management scheme minimizes the computational complexity of the cloud users by performing only one mathematical operation to find the new group key that was computed earlier by the data owner. In addition, this proposed key management scheme is suitable for a cloud network. Third, the proposed key distribution and key management scheme utilizes privacy preserving methods, thus preserving the privacy of the user. Finally, a batch key updating algorithm (also called batch rekeying) has been proposed to reduce the number of rekeying operations required for performing batch leave or join operations. The key management scheme proposed in this thesis is designed to reduce the computation and communication complexity in all but a few cases, while increasing the security and privacy of the data.

  • 136.
    Katsikas, Georgios P.
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Network Systems Laboratory (NS Lab).
    Enguehard, Marcel
    Kuźniar, Maciej
    Maguire Jr, Gerald Q.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Kostic, Dejan
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Network Systems Laboratory (NS Lab).
    SNF: synthesizing high performance NFV service chains2016In: PeerJ Computer Science, ISSN 2376-5992, p. 1-30Article in journal (Refereed)
    Abstract [en]

    In this paper we introduce SNF, a framework that synthesizes (S) network function (NF) service chains by eliminating redundant I/O and repeated elements, while consolidating stateful cross layer packet operations across the chain. SNF uses graph composition and set theory to determine traffic classes handled by a service chain composed of multiple elements. It then synthesizes each traffic class using a minimal set of new elements that apply single-read-single-write and early-discard operations. Our SNF prototype takes a baseline state of the art network functions virtualization (NFV) framework to the level of performance required for practical NFV service deployments. Software-based SNF realizes long (up to 10 NFs) and stateful service chains that achieve line-rate 40 Gbps throughput (up to 8.5x greater than the baseline NFV framework). Hardware-assisted SNF, using a commodity OpenFlow switch, shows that our approach scales at 40 Gbps for Internet Service Provider-level NFV deployments.

  • 137.
    Katsikas, Georgios P.
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Network Systems Laboratory (NS Lab).
    Maguire Jr., Gerald Q.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Kostic, Dejan
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Network Systems Laboratory (NS Lab).
    Profiling and accelerating commodity NFV service chains with SCC2017In: Journal of Systems and Software, ISSN 0164-1212, E-ISSN 1873-1228, Vol. 127, no C, p. 12-27Article in journal (Refereed)
    Abstract [en]

    Recent approaches to network functions virtualization (NFV) have shown that commodity network stacks and drivers struggle to keep up with increasing hardware speed. Despite this, popular cloud networking services still rely on commodity operating systems (OSs) and device drivers.

     

    Taking into account the hardware underlying of commodity servers, we built an NFV profiler that tracks the movement of packets across the system’s memory hierarchy by collecting key hardware and OS-level performance counters.

     

    Leveraging the profiler’s data, our Service Chain Coordinator’s (SCC) runtime accelerates user-space NFV service chains, based on commodity drivers. To do so, SCC combines multiplexing of system calls with scheduling strategies, taking time, priority, and processing load into account.

     

    By granting longer time quanta to chained network functions (NFs), combined with I/O multiplexing, SCC reduces unnecessary scheduling and I/O overheads, resulting in three-fold latency reduction due to cache and main memory utilization improvements. More importantly, SCC reduces the latency variance of NFV service chains by up to 40x compared to standard FastClick chains by making the average case for an NFV chain to perform as well as the best case. These improvements are possible because of our profiler’s accuracy.

  • 138.
    Khodabandehloo, Elmira
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    JavaFX Scene Graph Object Serialization2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Data visualization is used in order to analyze and perceive patterns in data. One of the use cases of visualization is to graphically represent and compare simulation results. At Ericsson Research, a visualization platform, based on JavaFX 2 is used to visualize simulation results. Three configuration files are required in order to create an application based on the visualization tool: XML, FXML, and CSS.

    The current problem is that, in order to set up a visualization application, the three configuration files must be written by hand which is a very tedious task. The purpose of this study is to reduce the amount of work which is required to construct a visualization application by providing a serialization function which makes it possible to save the layout (FXML) of the application at run-time based solely on the scene graph.

    In this master’s thesis, possible frameworks that might ease the implementation of a generic FXML serialization have been investigated and the most promising alternative according to a number of evaluation metrics has been identified. Then, using a design science research method, an algorithm is proposed which is capable of generic object/bean serialization to FXML based on a number of features or requirements. Finally, the implementation results are evaluated through a set of test cases. The evaluation is composed of an analysis of the serialization results & tests and a comparison of the expected result and the actual results using unit testing and test coverage measurements.

    Evaluation results for each serialization function show that the results of the serialization are similar to the original files and hence the proposed algorithm provides the desired serialization functionality for the specific features of FXML needed for this platform, provided that the tests considered every aspect of the serialization functionality.

  • 139.
    Kim, Young Suh
    et al.
    Center for Fundamental Physics, University of Maryland, College Park, MD 20742, USA.
    Maguire Jr., Gerald Q.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Noz, Marilyn E.
    New York University, Department of Radiology, Nuclear Medicine.
    Do Small-Mass Neutrinos Participate in Gauge Transformations?2016In: Advances in High Energy Physics, ISSN 1687-7357, E-ISSN 1687-7365, p. 1-7, article id 1847620Article in journal (Refereed)
    Abstract [en]

    Neutrino oscillation experiments presently suggest that neutrinos have a small but finite mass. If neutrinos have mass, there should be a Lorentz frame in which they can be brought to rest. This paper discusses how Wigner’s little groups can be used to distinguish between massive and massless particles. We derive a representation of the SL(2,c) group which separates out the two sets of spinors: one set is gauge dependent and the other set is gauge invariant and represents polarized neutrinos. We show that a similar calculation can be done for the Dirac equation. In the large-momentum/zero-mass limit, the Dirac spinors can be separated into large and small components. The large components are gauge invariant, while the small components are not. These small components represent spin-1/2 non-zero-mass particles. If we renormalize the large components, these gauge invariant spinors represent the polarization of neutrinos. Massive neutrinos cannot be invariant under gauge transformations.

  • 140.
    Kim, Yunesung
    et al.
    Yonsei University.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Hwang, Taewon
    Yonsei University.
    Energy Efficient Pilot and Link Adaptation for Mobile Users in TDD Multi-User MIMO Systems2014In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 13, no 1, p. 382-393Article in journal (Refereed)
    Abstract [en]

    In this paper, we develop an uplink pilot and downlink link adaptation approach to improve the energy efficiency (EE) of mobile users in time division duplexing (TDD) multi-user multiple input and multiple output (MU-MIMO) systems. Assuming reciprocity between uplink and downlink channels, the downlink transmission is based on uplink channel estimation. While more uplink pilot power ensures more accurate channel estimation and better downlink performance, it incurs higher energy consumption of mobile users. This paper reveals the relationship and tradeoff among pilot power, channel estimation, and downlink link adaptation that achieves the highest energy efficiency for mobile users. We show that the energy efficiency of different users can be decoupled because the downlink average throughput of each user is independent of the pilot powers of other users and energy-efficient design can be done on a per-user basis. Based on the analysis, we propose an uplink pilot and downlink link adaptation algorithm to improve the EE of mobile users. Simulation results are finally provided to demonstrate the significant gain in energy efficiency for mobile users.

  • 141.
    Knertser, Denys
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Tsarinenko, Victor
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Network Device Discovery2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Modern heterogeneous networks present a great challenge for network operators and engineers from a management and configuration perspective. The Tail-f Systems’ Network Control System (NCS) is a network management framework that addresses these challenges. NCS offers centralized network configuration management functionality, along with providing options for extending the framework with additional features. The devices managed by NCS are stored in its Configuration Database (CDB). However, currently there is no mechanism for automatically adding network devices to the configuration of NCS, thus each device’s management parameters have to be entered manually. The goal of this master’s thesis project is to develop a software module for NCS that simplifies the process of initial NCS configuration by allowing NCS to automatically add network devices to the NCS CDB.

    Apart from developing the software module for discovery, this project aims to summarize existing methods and to develop new methods for automated discovery of network devices with the main focus on differentiating between different types of devices. A credential-based device discovery method was developed and utilized to make advantage of known credentials to access devices, which allows for more precise discovery compared to some other existing methods. The selected methods were implemented as a component of NCS to provide device discovery functionality.

    Another focus of this master’s thesis project was the development of an approach to network topology discovery and its representation. The aim is to provide both a logical Internet Protocol (IP) network topology and a physical topology of device interconnections. The result is that we are able to automatically discover and store the topology representation as a data structure, and subsequently generate a visualization of the network topology.

  • 142.
    Kohen, Alexandre
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Unified Communications with Lync 20132013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Unified Communications solutions bring together several communication modes, technologies, and applications in order to answer businesses’ and individuals’ growing need for simpler, faster, and more effective communications means.  Although many hardware-based products allow the integration of telephony within a computer network environment, telephony features of software-based unified communications solutions are seldom used, which limits their effectiveness or requires another solution to be used jointly.

    This master’s thesis project aims to demonstrate that unified communications solutions based on Microsoft Lync Server 2013 can effectively address a wide variety of business scenarios, including a traditional telephony system replacement.  The first part of this master’s thesis introduces background knowledge about unified communications and associated technologies, as well as the different components of the selected unified communication solution.

    The case study presented in this thesis is the first large-scale Lync 2013 deployment with a complete telephony offering in France. The presentation follows the complete deployment process, starting from the analysis of the client’s needs to the solution design, construction, and validation.

    This project demonstrated the suitability of Lync 2013 as a telephony system replacement. However, the transition from a classic telephony solution to a unified communications solution can be a technical challenge. An essential step in making this transition successful was to take the users’ needs into account. It was also essential to accompany these users throughout the transition.

  • 143.
    Kokkalis, Andreas
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Prelipcean, Adrian Corneliu
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Extracting and Integrating Meta-data from online sources: A set of examples leading to improved course and instructor selection2014Report (Other academic)
    Abstract [en]

    The recent advances in Natural Language Processing (NLP), association based algorithms and recommendation systems enabled suppliers to personalize the content offered to their clients / subscribers. However, their use has been limited to either the industrial environment or to the research one, leaving the education environment lacking when it comes to such tools. This report focuses on exploring the use of recommendation systems in education. First, it presents methods that are suitable for extracting meta-data that can be used to derive certain associations and / or suggestions. Second, it proposes a method that suggests courses and / or tutors based on a student's interest. Third, it provides DocAid, which is an API suitable for extracting meta-data from different sources. Finally, a web application is built on top of DocAidto make the aforementioned functionality available for others to use.

  • 144.
    Lara Peinado, Javier
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Minding the spectrum gaps: First steps toward developing a distributed white space sensor grid for cognitive radios2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The idea that the radio spectrum is growing ever more scarce has become commonplace, and is being reinforced by the recent bidding wars among telecom operators. New wireless applications tend to be deployed in the relatively narrow unlicensed frequency bands, worsening the problem of interference for all users.  However, not all frequency bands are in use in every location all the time, creating temporal and spatial gaps (also known as white spaces) that cognitive radio systems aim to take advantage of. In order to achieve that, such systems need to be able to constantly scan large chunks of the radio spectrum to keep track of which frequency bands are locally available any given moment, thus allowing users to switch to one of these unoccupied frequency bands once the current band becomes unusable (or less useful). This requirement of wideband sensing capabilities often translates into the need to install specialized radio components, raising the costs of such systems, and is often at odds with the focus on monitoring the current band as is done by traditional wireless devices.

    The goal of this master’s thesis project is to simplify cognitive radio systems by shifting the wideband sensing functionality to a specialized and inexpensive embedded platforms that will act as a white space sensor, thus freeing cognitive radio users from this task and making it easier to integrate dynamic spectrum management techniques into existing systems. To do that a wireless sensor gateway platform developed by a previous master’s thesis has been repurposed as a prototype white space detector and tested against several wireless transmitters.  The aim is to develop a standalone platform that can be deployed all around an area to collect data that can be used to create a geographical map of the use of the spectrum. Such a system should require as little maintenance as possible, thus auto-update and self-configuring features have been implemented in the detector, as well as a simple scanning protocol that allows for remote configuration of the wideband sensing parameters. Furthermore, a basic server has been developed to aggregate and display the data provided by the different sensors.

  • 145.
    Larsson, Magnus
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Sanitization of embedded network devices: Investigation of vendor’s factory reset procedure2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Embedded devices such as routers, switches, and firewalls commonly have sensitive information stored on them such as passwords, cryptographic keys, and information about the network around them and services that these device(s) provide. When disposing of or reselling this equipment in the secondary market it is crucial to erase this sensitive information. However, there is an important question that must be asked: Do the erase commands and routines offered by the device manufacturers actually erase the sensitive data?

    This thesis investigates methods and tools to determine the completeness of this erasure in some common network devices. These methods are used on a sample of networking equipment found to still contain sensitive information after being erased according to vendor recommendations. A computer program was developed to show how this information can be removed.

    The information in this document is useful for equipment owners, brokers and others looking to remarket their current equipment; all of whom want to minimize the risk of leaking sensitive data to other parties.

  • 146.
    Laya, Andres
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Alonso, L.
    Alonso-Zarate, J.
    Efficient Contention Resolution in Highly Dense LTE Networks for Machine Type Communications2015In: 2015 IEEE Global Communications Conference, GLOBECOM 2015, Institute of Electrical and Electronics Engineers (IEEE), 2015, article id 7417669Conference paper (Refereed)
    Abstract [en]

    In this paper, we propose a solution to efficiently handle the initial access contention for highly dense LTE networks, which still represents a challenge in terms of the high number of devices associated to Machine Type Communications. The analysis is based on the fact that, as the radius of a LTE cell is larger, the number of available preambles generated from a single root sequence is reduced. The current access mechanism, based on frame-slotted ALOHA, does not operate efficiently under these conditions, negatively affecting the access delay and collision probability. We show how the access procedure can be improved by implementing tree-splitting algorithms in order to cope with high number of simultaneous arrivals in large cells, above 5 km in radius. The implementation achieves as much as 85% reduction on the access delay and 54% reduction on energy consumption for cells with radius larger than 39 km.

  • 147.
    Laya, Andres
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Alonso, Luis
    Alonso-Zarate, Jesus
    Dohler, Mischa
    Green MTC, M2M, Internet of Things2015In: Green Communications: Principles, Concepts and Practice / [ed] Konstantinos Samdanis, Peter Rost, Andreas Maeder, Michela Meo and Christos Verikoukis, John Wiley & Sons, 2015, p. 217-236Chapter in book (Refereed)
    Abstract [en]

    The capability of having any type of object interconnected and Internet-connected creates an unprecedented access and exchange of information that has been baptized as the Internet of Things (IoT). With the advancement of integrated technologies, improved batteries, and electronic miniaturization, everyday things will be equipped with sensors and microprocessors to collect information around them and execute smart applications. In addition, they will be able to communicate with each other. The IoT has the potential to revolutionize innovations; create new products, services, business; and reshape consumer’s behavior. IoT represents a major player for the future of Information and Communications Technologies (ICT).The development of the IoT must be environment friendly. ICT have shown to be a key contributor to global warming and environmental pollution; it is predicted that the global greenhouse gas (GHG) emissions from ICT will account for 12% of all emissions by 2020 at a growth rate of 6% per year. Therefore, it is mandatory to develop environmentally friendly - or “green” - technologies for the IoT, and ICT in general.Machine-to-Machine (M2M) communications constitute a fundamental part of the IoT. The term M2M refers to the exchange of data between two or more entities, objects, or machines that do not necessarily need human interaction. The envisioned market for such kind of communications is broader than the one traditional human-based communications in terms of number of users and variety of applications. Some forecasts predict figures up to 50 billion machines that will be connecting to communication networks by 2020. This is a very big number compared to the entire world population of around 7 billion people. Therefore, there are some challenges that need to be addressed in order to fully supportM2Mservices in current communication networks. From the technical point of view, M2M communications are substantially different from Human-to-Human (H2H) communications. For example, network operators should provide communication services at low cost in order to face the low Average Revenue Per User (ARPU). Despite the large number of expected M2M connections, most of them will generate very little and infrequent data traffic. Communication networks shall also provide suitable congestion and overload control solutions in order to handle a huge number of simultaneous connections. Features such as low mobility, time-controlled data delivery, group-based policing and addressing, low connection delays, and a wide variety of Quality of Service requirements are among other challenges that need to be addressed. All of them must have the “green” concept embedded. In order to ensure that devices can operate autonomously for years or even decades without human intervention, it is necessary to provide networks with highly efficient communication protocols. This is the main focus of this chapter.The European Telecommunications Standards Institute (ETSI) created in 2009 a dedicated technical committee to identify key M2M use cases, understand the service requirements, and promote standards for the complete end-to-end M2M functional architecture. Later, in 2012, the global One M2M project was also established by ETSI, with other international standardization bodies, in order to define M2M standards that can accelerate the deployment and success of M2M applications.

  • 148.
    Laya, Andres
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). Universitat Politècnica de Catalunya (UPC), Catalunya, Spain.
    Alonso, Luis
    Chatzimisios, Periklis
    Alonso-Zarate, Jesus
    Reliable Machine-to-Machine Multicast Services with Multi-Radio Cooperative Retransmissions2015In: Mobile Networks and Applications , ISSN 1383-469X, E-ISSN 1572-8153, Vol. 20, no 6, p. 734-744Article in journal (Refereed)
    Abstract [en]

    The 3GPP is working towards the definition of service requirements and technical solutions to provide support for energy-efficient Machine Type Communications (MTC) in the forthcoming generations of cellular networks. One of the envisioned solutions consists in applying group management policies to clusters of devices in order to reduce control signaling and improve upon energy efficiency, e.g., multicast Over-The-Air (OTA) firmware updates. In this paper, a Multi-Radio Cooperative Retransmission Scheme is proposed to efficiently carry out multicast transmissions in MTC networks, reducing both control signaling and improving energy-efficiency. The proposal can be executed in networks composed by devices equipped with multiple radio interfaces which enable them to connect to both a cellular access network, e.g., LTE, and a short-range MTC area network, e.g., Low-Power Wi-Fi or ZigBee, as foreseen by the MTC architecture defined by ETSI. The main idea is to carry out retransmissions over the M2M area network upon error in the main cellular link. This yields a reduction in both the traffic load over the cellular link and the energy consumption of the devices. Computer-based simulations with ns-3 have been conducted to analyze the performance of the proposed scheme in terms of energy consumption and assess its superior performance compared to non-cooperative retransmission schemes, thus validating its suitability for energy-constrained MTC applications.

  • 149.
    Laya, Andres
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth. KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Bratu, Vlad Ioan
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth. KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Markendahl, Jan
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Who Is Investing in Machine-to-Machine Communications?2013In: 24th European Regional ITS Conference, Florence 2013, 2013Conference paper (Refereed)
    Abstract [en]

    Machine-to-Machine (M2M) communications refers to the automate exchange of information between devices for control and monitoring applications. This type of communication is not new since automated systems have been present for more than three decades. However, miniaturization of device’s size, reduction of production costs and drop in communication fees (altogether with the massive adoption of real-time access of information in current society) are expanding the set of applications and solutions currently under consideration. The real complexity relies on the fact that M2M is not only an add-on communication solution, like the case of traditional human-centric broadband communications. M2M usually entails a change in the core business of an industry, since the relationship with external partners and the internal tasks can be radically modified

    In this paper, we anaylise the players involved in M2M communications and how they position themselves in a market which requires them to adjust their traditional business approach. The main question addressed in this work refers to “which players are investing in M2M, which is their view and how could their approach affect the current ICT sector?” We highlight the dominance and relationship between different actors and also look at barriers that prevent investments, regulations in the area and standardization efforts.

    Using data from interviews, use case analysis, and expert workshops we place our analysis in a real-market context. It can be concluded that there is a consensus about the potential benefits of services based on M2M communications and key succes factors are partnerships among different actors, re-thinking of roles, e.g., transition to a service provider and defining the right type of value added service

  • 150.
    Laya, Andres
    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.
    Ghanbari, Amirhossein
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Markendahl, Jan
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Tele-economics in MTC: what numbers would not show2015In: EAI Endorsed Transactions on Internet of Things, ISSN 2414-1399, Vol. 1, no 1Article in journal (Refereed)
    Abstract [en]

    This paper elaborates on the relevance of Tele-Economic research to understand the effect that Machine-Type Commu- nications (MTC) has on different markets and also the market forces affecting the adoption of services based on MTC. The paper is presented in a tutorial form, offering concept and definitions of economic terms that are gaining relevance in the technical community in the MTC context. The concept of services is further analysed in as a change in the tele- communication industry mind-set in order to tap into the economic value of MTC in the realization of the Internet-of- Things. Finally, insights are presented looking forward into the relevance of Tele-Economic research for 5G.

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