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  • 251.
    Shi, Lei
    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.
    Sung, Ki Won
    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.
    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.
    Spectrum Requirement for Cellular TV distribution in UHF Band from Urban to Rural Environment2014In: 2014 IEEE International Symposium on Dynamic Spectrum Access Networks (DYSPAN), IEEE Computer Society, 2014, p. 362-365Conference paper (Refereed)
    Abstract [en]

    An the number of TV-channels increase and the number of viewers per channel decreases, Terrestrial Broadcasting is becoming a less attractive way to distribute TV. In addition it does not represent a very efficient use of the UHF band (470790 MHz). In this paper we discuss an alternative, converged platform for TV and mobile broadband provisioning based on LTE cellular technology and infrastructure, here referred to as CelITV. The key feature of Cell-TV is the ability to switch between a unicast mode for small viewer populations and broadcast over LTE single frequency networks (SFN) for popular content. The main advantage is that the spectrum can flexibly be shared with LTE mobile data services, effectively freeing significant parts of the UHF spectrum for these purposes. Based on a case study of the greater Stockholm area, significant potential for spectrum saving is identified in urban areas where the need for spectrum is the largest. Meanwhile, only limited spectrum savings are observed in rural areas due to the large user populations in each cell and the long inter-site distance. As most of the TV channels are broadcasted in urban areas but unicasted in rural areas, this switch of transmission modes causes considerably high spectrum demand in suburban areas.

  • 252.
    Sjöström, Daniel
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Unlicensed and licensed low-power wide area networks: Exploring the candidates for massive IoT2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the Internet of things (IoT), many applications will require low-power and low-cost to achieve long lifetime and scale (respectively). These types of applications are referred to as massive IoT, as opposed to critical IoT, which emphasizes ultra-high reliability and availability and low latency. One type of network catering to massive IoT applications are Low-Power Wide Area Networks (LPWANs), and presently, many LPWAN standards are trying to assert their role in the IoT ecosystem.

    This thesis explores LPWANs from both technical and non-technical perspectives to ascertain their use-case versatility and influence on the future telecommunications’ landscape. With respect to spectrum, the studied LPWANs may be categorized as unlicensed LPWAN or licensed LPWAN. The prior category typically refers to proprietary solutions and in this thesis are represented by SigFox and LoRaWAN. The latter group includes EC-GSM-IoT, eMTC, and NB-IoT and can be considered synonymous with cellular LPWAN because they are designed to be integrated into existing cellular infrastructures.

    The results indicate that all of the different types of explored LPWANs support applications without strict downlink, payload size, and latency requirements. For use cases without these specific demands (typically sensors, meters, tracking, etc.), it is not a question of whether or not a network fulfills the requirements, but rather how flexible the requirements are. As a result the choice of network will be determined by non-technical aspects and a cost versus functionality trade-off where unlicensed LPWAN is typically cheaper. Hence, both categories of LPWANs offer a unique value proposition; therefore, they can be considered complementary. This notion is reinforced when looking at non-technical aspects such as ecosystem, regulation, network ownership and control, and network coordination, which differ quite significantly. Furthermore, unlicensed LPWANs are likely to be the vanguard of a new type of competitor offering the core service of connectivity.

  • 253.
    Skeppholm, Martin
    et al.
    Stockholm Spine Center, Löwenströmska Sjukhuset.
    Svedmark, Per
    Karolinska Institutet at Karolinska University Hospital Solna.
    Noz, Marilyn E.
    New York University.
    Maguire Jr., Gerald Q.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Olivecrona, Henrik
    Olerud, Claes
    Department of Orthopedic Surgery, Uppsala University Hospital.
    Evaluation of mobility and stability in the Discover artificial disc: an in vivo motion study using high-accuracy 3D CT data2015In: Journal of Eurosurgery : Spine, ISSN 1547-5654, E-ISSN 1547-5646, Vol. 23, no 3, p. 383-389Article in journal (Refereed)
    Abstract [en]

    OBJECT Artificial disc replacement (ADR) devices are unlike implants used in cervical fusion in that they are continuously exposed to stress not only within the implant site but also at their site of attachment to the adjacent vertebra. An imaging technique with higher accuracy than plain radiography and with the possibility of 3D visualization would provide more detailed information about the motion quality and stability of the implant in relation to the vertebrae. Such high-accuracy studies have previously been conducted with radiostereometric analysis (RSA), which requires implantation of tantalum markers in the adjacent vertebrae. The aim of this study was to evaluate in vivo motion and stability of implanted artificial discs. A noninvasive analysis was performed with CT, with an accuracy higher than that of plain radiographs and almost as high as RSA in cervical spine. METHODS Twenty-eight patients with ADR were included from a larger cohort of a randomized controlled trial comparing treatment of cervical radiculopathy with ADR or anterior cervical decompression and fusion. Surgical levels included C4-7; 18 patients had 1-level surgery and 10 patients had 2-level surgery. Follow-up time ranged from 19 to 50 months, with an average of 40 months. Two CT volumes of the cervical spine, 1 in flexion and 1 in extension, were obtained in each patient and then spatially registered using a customized imaging tool, previously used and validated for the cervical spine. Motion between the components in the artificial disc, as well as motion between the components and adjacent vertebrae, were calculated in 3 planes. Intraclass correlation (ICC) between independent observers and repeatability of the method were also calculated. RESULTS Intrinsic motion, expressed as degrees in rotation and millimeters in translation, was detectable in a majority of the ADRs. In the sagittal plane, in which the flexion/extension was performed, sagittal rotation ranged between 0.2 and 15.8 and translation between 0.0 and 5.5 mm. Eight percent of the ADRs were classified as unstable, as motion between at least 1 of the components and the adjacent vertebra was detected. Five percent were classified as ankylotic, with no detectable motion, and another 8% showed very limited motion due to heterotopic ossification. Repeatability for the motion in the sagittal plane was calculated to be 1.300 for rotation and 1.29 mm for translation (95% confidence level), ICC 0.99 and 0.84, respectively. All 3 patients with unstable devices had undergone 1-level ADRs at C5-6. They all underwent revision surgery due to increased neck pain, and instability was established during the surgery. CONCLUSIONS The majority of the artificial discs in this study showed intrinsic mobility several years after implantation and were also shown to be properly attached. Implant instability was detected in 8% of patients and, as all of these patients underwent revision surgery due to increasing neck pain, this might be a more serious problem than heterotopic bone formation.

  • 254.
    Skogsberg, Peter
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Quantitative indicators of a successful mobile application2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The smartphone industry has grown immensely in recent years. The two leading platforms, Google Android and Apple iOS, each feature marketplaces offering hundreds of thousands of software applications, or apps. The vast selection has facilitated a maturing industry, with new business and revenue models emerging. As an app developer, basic statistics and data for one's apps are available via the marketplace, but also via third-party data sources.

    This report regards how mobile software is evaluated and rated quantitatively by both endusers and developers, and which metrics are relevant in this context. A selection of freely available third-party data sources and app monitoring tools is discussed, followed by introduction of several relevant statistical methods and data mining techniques. The main object of this thesis project is to investigate whether findings from app statistics can provide understanding in how to design more successful apps, that attract more downloads and/or more revenue.

    After the theoretical background, a practical implementation is discussed, in the form of an in-house application statistics web platform. This was developed together with the app developer company The Mobile Life, who also provided access to app data for 16 of their published iOS and Android apps. The implementation utilizes automated download and import from online data sources, and provides a web based graphical user interface to display this data using tables and charts.

    Using mathematical software, a number of statistical methods have been applied to the collected dataset. Analysis findings include different categories (clusters) of apps, the existence of correlations between metrics such as an app’s market ranking and the number of downloads, a long-tailed distribution of keywords used in app reviews, regression analysis models for the distribution of downloads, and an experimental application of Pareto’s 80-20 rule which was found relevant to the gathered dataset.

    Recommendations to the app company include embedding session tracking libraries such as Google Analytics into future apps. This would allow collection of in-depth metrics such as session length and user retention, which would enable more interesting pattern discovery.

  • 255. Stenumgaard, Peter
    et al.
    Chilo, Jose
    Ferrer Coll, Javier
    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.
    Ängskog, Per
    Challenges and conditionsfor wireless machine-to-machine communications in industrial environments2013In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 51, no 6, p. 187-192Article in journal (Refereed)
    Abstract [en]

    Wireless solutions are rapidly growing in machine-to-machine communications in industrial environments. These environments provide challenging conditions in terms of radio wave propagation as well as electromagnetic interference. In this article, results from the characterization of radio channel properties are summarized in order to provide some guidelines for the choice of wireless solutions in industrial environments. In conclusion, it is essential to know the sensitivity of industrial processes to time delay in data transfer. Furthermore, it is important to be aware of the radio interference environment and the manner in which different wireless technologies react upon interference. These steps will minimize the risk of unforeseen expensive disturbances in industrial processes.

     

  • 256.
    Stjern, Magnus
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Jansson Aldenfalk, Staffan
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Investigation of pattern recognition algorithms to determine depth and volume of water inside the sump of a pumping station2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Pattern recognition is now considered a fundamental building block in many fields.  The ability to interact with a computer or vice versa is no longer limited by how fast the computer is, but rather what an application developer can think of. Today many modern, real-time applications, such as high performance and high quality graphics can be combined with a Xbox Kinect to do object tracking and Google Glass to provide a heads up display. These applications can also be combined with other sensors and actuators to produce monitoring systems that can give facilities' operators "telepresence" throughout a facility. To be able to computationally interpret movement or patterns in an image it is imperative to investigate the application of this technology.

    The research conducted at Xylem has focused on a very specific problem: How can pattern recognition be utilized to dynamically determine the volume and depth of water in a sump at a pumping station. The equipment currently used to determine the water level depends upon being either below or alongside the water's surface, this puts the equipment under great stress due to the nature of a pumping station. Xylem is one of the leading global water technology companies, hence sewage-pumps are one of its main products. The main equipment utilized in this thesis project consists of a camera attached to the interior at the top of the sump in a pumping station connected to a computer.

    The software developed includes a simple graphical user interface (GUI). This GUI was implemented in C# and is designed to continuously collect data from a camera for subsequent analysis. Our algorithm utilizes anti-correlation between many images taken during a short interval to determine the actual water level. The known dimensions of the sump are then used to calculate the volume of water.

    Most of the depth values produced by our software were correct and we were able to correctly estimate the water level with an error of less than 4 cm, this corresponds to a volume error of 62 liters for a 140 cm wide sump. Our algorithm was able to monitor the depth over time inside a pumping station in a simulated live environment.  This accuracy is obtained with a time window of 1 second. The results of this system are important because it shows that it is possible to use a camera to measure water depth. This provides pump owners and operators with valuable information regarding the current state of the pump, both in terms of current water depth and an image of possible anomalies such as the presence of foreign objects in the sump.

  • 257.
    Svedmark, Per
    et al.
    Karolinska Institutet at Karolinska University Hospital Solna.
    Berg, Svante
    Stockholm Spine Center, Löwenströmska Hospital.
    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).
    Zeleznik, Michael P.
    University of Utah.
    Weidenhielm, Lars
    Karolinska Institutet at Karolinska University Hospital Solna.
    Nemeth, Gunnar
    Capio S:t Göran Sjukhuset.
    Olivecrona, Henrik
    A New CT Method for Assessing 3D Movements in Lumbar Facet Joints and Vertebrae in Patients before and after TDR2015In: BioMed Research International, ISSN 2314-6133, Vol. 2015, p. 1-9, article id 260703Article in journal (Refereed)
    Abstract [en]

    This study describes a 3D-CT method for analyzing facet joint motion and vertebral rotation in the lumbar spine after TDR. Ten patients were examined before and then three years after surgery, each time with two CT scans: provoked flexion and provoked extension. After 3D registration, the facet joint 3D translation and segmental vertebral 3D rotation were analyzed at the operated level (L5-S1) and adjacent level (L4-L5). Pain was evaluated using VAS. The median (±SD) 3D movement in the operated level for the left facet joint was 3.2 mm (±1.9 mm) before and 3.5 mm (±1.7 mm) after surgery and for the right facet joint was 3.0 mm (±1.0 mm) before and 3.6 mm (±1.4 mm) after surgery. The median vertebral rotation in the sagittal plane at the operated level was 5.4° (±2.3°) before surgery and 6.8° (±1.7°) after surgery and in the adjacent level was 7.7° (±4.0°) before and 9.2° (±2.7°) after surgery. The median VAS was reduced from 6 (range 5–8) to 3 (range 2–8) in extension and from 4 (range 2–6) to 2 (range 1–3) in flexion.

  • 258.
    Svensson, Carl
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Automatic Log Analysis System Integration: Message Bus Integration in a Machine Learning Environment2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Ericsson is one of the world's largest providers of communications technology and services. Reliable networks are important to deliver services that live up to customers' expectations. Tests are frequently run on Ericsson's systems in order to identify stability problems in their networks. These tests are not always completely reliable. The logs produced by these tests are gathered and analyzed to identify abnormal system behavior, especially abnormal behavior that the tests might not have caught. To automate this analysis process, a machine learning system, called the Awesome Automatic Log Analysis Application (AALAA), is used at Ericsson's Continuous Integration Infrastructure (CII)-department to identify problems within the large logs produced by automated Radio Base Station test loops and processes. AALAA is currently operable in two versions using different distributed cluster computing platforms: Apache Spark and Apache Hadoop. However, it needs improvements in its machine-to-machine communication to make this process more convenient to use. In this thesis, message communication has successfully been implemented in the AALAA system. The result is a message bus deployed in RabbitMQ that is able to successfully initiate model training and abnormal log identification through requests, and to handle a continuous flow of result updates from AALAA.

  • 259.
    Sällberg, Kristian
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    A Data Model Driven Approach to Managing Network Functions Virtualization: Aiding Network Operators in Provisioning and Configuring Network Functions2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master’s thesis explains why certain network services are difficult to provision and configure using IT automation and cloud orchestration software. An improvement is proposed and motivated. This proposed improvement enables network operators to define a set of data models describing how to provision and interconnect a set of Virtual Network Functions (VNFs) (and possibly existing physical network functions) to form networks. Moreover, the proposed solution enables network operators to change the configuration at runtime. The work can be seen as a step towards self managing and auto scaling networks.

    The proposed approach is compared to a well known cloud management system (OpenStack) in order to evaluate if the proposed approach decreases the amount of time needed for network operators to design network topologies and services containing VNFs. Data is collected through observations of network operators, interviews, and experiment.

    Analysis of this data shows that the proposed approach can decrease the amount of time required for network operators to design network topologies and services. This applies if the network operators are already acquainted with the data modeling language YANG. The amount of time required to provision VNFs so that they respond to connections can also be decreased using the proposed approach. The proposed approach does not offer as much functionality as OpenStack, as it is limited to VNF scenarios.

  • 260.
    Talic, Ammar
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Security Analysis of Ethernet in Cars2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With the development of advanced driving assistance systems, the amount of data that needs to be transmitted within a car has increased tremendously. Traditional communication bus based systems are unable to meet today’s requirements; hence automotive Ethernet is being developed and standardized.

    Ethernet has for many years been the de facto standard in interconnecting computers. In that time several vulnerabilities of the networking protocol stack implementations and even the protocols themselves have been discovered. The knowledge from exploiting computer networks can be applied to the automotive domain. Additionally, vehicle manufacturers tend to implement their own stacks, due to copyleft reasons; hence the chances of implementation faults increases as opposed to using well-tested open source solutions. Since the line between security and safety in cars is almost nonexistent, security has to be properly addressed.

    This thesis investigates the security of automotive Ethernet and its accompanying protocols. It starts with an introduction to computer and automotive networking and protocols. After a solid foundation is laid, it investigates what makes up automotive Ethernet, its application in the field, and the automotive specific components relying on it. After looking at related work, a data network security audit and analysis as defined by the open-source security testing methodology is performed. The system is graded with risk assessment values. Weak points are identified and improvements suggested. The impact of the proposed improvements is shown by reevaluating the system and recalculating the risk assessment values.

    These efforts further the ultimate goal of achieving increased safety of all traffic participants.

  • 261.
    Tarhan, Aras
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    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.
    Shared path protection for distance adaptive elastic Optical Networks under dynamic traffic2013In: 2013 5th International Congress on Ultra Modern Telecommunications and Control Systems and Workshops (ICUMT), IEEE Computer Society, 2013, p. 62-67Conference paper (Refereed)
    Abstract [en]

    Elastic Optical Networks (EONs), evolved as a scalable infrastructure to provide optical connectivity for large variety of bandwidth requests ranging from 1Gbps to 1Tbps. Thanks to the enabling technologies such as bandwidth variable transponders and flexible switches, bandwidth adaptive spectrum allocation became possible. EONs can carry large optical channels with higher spectrum efficiency with the recent changes in the standard fixed division of optical spectrum. In this study we propose a distance adaptive, dynamic shared path protection scheme for EONs. In conventional WDM networks, sharability used to be one of the prime objectives to maximize the backup resource efficiency. In EONs, spectrum resources can be shared partially between connections and different parts of the allocated spectrum may be shared by different connections at the same time. Not only the routing but also spectrum allocation of backup resources has a big impact on the sharability in EONs. Taking this into account, we developed a novel RSA (Routing and Spectrum Allocation) algorithm applying different strategies for primary and backup resources called Primary First-Fit Modified Backup Last-Fit (PF-MBL) aiming to reduce the fragmentation and to increase the sharability. As a result overall bandwidth blocking probability is significantly reduced in the network. Results show that PF-MBL can improve the performance in terms of bandwidth blocking probability by 24% up to 59% compared to the current outperforming algorithm when the bandwidth acceptance ratio of the system varies from 90% to 99.9% in different loads.

  • 262.
    Tecsor, Irina
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Isaksson, Gunnar
    Luleå tekniska universitet.
    Borg, Johan
    Luleå tekniska universitet.
    Beckman, Claes
    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. Luleå University of Technology, Sweden.
    Initial Investigations into the Effects of Mutual Coupling and Architecture of the EISCAT3D array2013Conference paper (Other academic)
    Abstract [en]

    To study the layers of the ionosphere and also the interactions between Earth and Sun, the EISCAT association will build a three dimensional imaging radar: EISCAT3D. The infra­structure of the radar system will include 5 sites with ~10000 antenna elements each.

    For such arrays, the electromagnetic interaction between radiating elements (coupling effects) and the influence of the ground plane cannot be neglected. In addition, for array applications requiring a large number of elements, a process called thinning is most often applied to remove elements while maintaining much of the same characteristics for the antenna. When the density of components decreases, the coupling in the array will decrease as well.

    The relative position of elements doesn’t have a great influence on the performance of main beam. It has, however, on the mutual coupling that changes the input impedance of the radiators and the characteristics of the radiation pattern. The challenge is to find a layout where radiating elements will be separated enough for them not to couple but close enough to not disturb the performance of the array antenna.

    For the purpose of analyzing the performance of the EISCAT3D array, a simulation tool has been developed in Matlab/ Mathematica. In this initial study, thinned arrays with three types of elements: isotropic, half wavelength dipoles and an antenna element designed and simulated at Luleå Technical University are investigated. The latter element was designed with the ambition to meet the rigorous requirements put on the EISCAT3D array when deployed in the Northern part of Scandinavia in order to withstand the harsh environment. The radiation pattern of the single radiator is provided by an EM simulation tool (NEC2) and

    includes the mutual coupling to identical elements. Thus, analyzing the radiation pattern of the array with Luleå elements, the mutual coupling effects are taken into consideration.

    In the simulations an attempt is made to, in a realistic manner and for different scanning angles, calculate per­formance indicators such as Directivity and Sidelobe level. When the main beam is directed towards the zenith, it was found that between the three elements analyzed, dipoles will result in the lowest directivity and the smallest side lobe level. The directivity of the array with isotropic elements and Luleå elements increases with a regular pattern with increasing number of elements. Between the three types of radiators, Luleå elements will results in the highest average side lobe level and the peak side lobe level gets better than isotropic elements when more than 60% of elements are active.

  • 263.
    Tercero, Miurel
    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.
    Sung, Ki Won
    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.
    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.
    Exploiting Temporal Secondary Access Opportunities in Radar Spectrum2013In: Wireless personal communications, ISSN 0929-6212, E-ISSN 1572-834X, Vol. 72, no 3, p. 1663-1674Article in journal (Refereed)
    Abstract [en]

    In this paper, we quantify the temporal opportunities for secondary access to radar spectrum. Secondary users are assumed to be WLANs which opportunistically share the radar frequency band under the constraint that the aggregate interference does not harm radar operation. Each WLAN device employs dynamic frequency selection (DFS) as a mechanism to protect the radar from the interference. We also consider an advanced interference protection mechanism, which is termed temporal DFS. It exploits the temporal variation of interference power due to the periodic rotation of radar antenna. It is observed that the probability of accessing the radar spectrum is significantly higher when the temporal DFS is used compared to the conventional DFS. As a consequence, more WLANs can utilize the radar spectrum when the temporal DFS mechanism is considered. This shows that having better knowledge of the primary user activity can bring about the increased opportunity of secondary spectrum access to radar band, and thus improve the spectrum utilization.

  • 264.
    Thanos, Anastasios
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Shalmashi, Serveh
    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.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Network-Assisted Discovery for Device-to-Device Communications2013In: 2013 IEEE Globecom Workshops (GC Wkshps), IEEE Computer Society, 2013, p. 660-664Conference paper (Refereed)
    Abstract [en]

    Network-assisted device-to-device (D2D) communications allow two devices to communicate with each other directly using one bidirectional link. Exchange of signaling messages with the base station allows the establishment of D2D communications. The discovery of D2D pairs of devices is an essential part of D2D communications as it provides the base station with all the information necessary to evaluate the possibility of D2D communication for the pair. This paper proposes two discovery algorithms, the centralized fully network-dependent and the semi centralized semi-network-dependent algorithms to identify D2D pairs through the exchange of a number of signaling messages. A comparison between those algorithms is performed with respect to delay and signaling overhead. Simulation results show that the second discovery algorithm is faster and more efficient than the first one in discovering new D2D pairs.

  • 265.
    Thießen, Christian
    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).
    Fragmentation-aware survivable Routing and Spectrum Assignment in elastic optical networks2014In: Proceedings of 2014 6th International Workshop on Reliable Networks Design and Modeling, RNDM 2014, IEEE , 2014, p. 97-101Conference paper (Refereed)
    Abstract [en]

    Transparent elastic optical networks (EON) allow provisioning connections with different bandwidth requirements in an efficient way. To achieve the high spectrum efficiency under dynamic traffic scenario, fragmentation-aware Routing, Modulation and Spectrum Assignment (RMSA) decisions is essential. Since fiber cuts are common, resiliency against single-link failures is another important topic. This can be provided efficiently through shared-path protection, which in turn complicates the connection provisioning problem. Unlike existing algorithms that decide first the primary and then the backup path, we introduce an algorithm in this paper that considers pairs of primary and backup paths. To select a candidate pair, we use a hybrid cost function that combines three different objectives: (1) the separation of primary and backup connections to different ends of the spectrum; (2) fragmentation-awareness as a pro-active provisioning objective trying to avoid fragmentation especially among primary resources and (3) maximization of shareability of backup resources among primary paths of link-disjoint connections. Using network level simulations in a scaled-down sample US network with load values of 190-240 Erlang, and bandwidth requests corresponding to 1% blocking probability, an average improvement of 79% compared to a recently presented reference algorithm is shown.

  • 266.
    Tomar, Abhineet Singh
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Modern Electrical/Electronic Infrastructure for Commercial Trucks: Generic Input/Output nodes for sensors and actuators in Commercial Trucks2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The presence of electrical and electronic circuits in commercial trucks has increased at a very fast rate during recent decades. With advancements in embedded systems and the introduction of electric controls in the automotive industry, the design of complex electric systems for the vehicles has become one of the major design challenges. In the commercial truck industry, the development cycles are almost a decade long. Therefore, it is a big challenge to introduce a new architecture to accommodate the modern automotive technologies in the upcoming generation of trucks.

    Currently, the commercial truck industry relies highly on a federated electrical/electronic (E/E) architecture. In this architecture, Electronic Control Units (ECU) are responsible for computation and Input/Output operations. These ECUs are clustered into different domains based on their respective functions. However, these domains are not isolated from each other. These modules communicate with each other using a vehicular network, which is typically a controller area network in the current trucks.

    In the automotive industry, automation is increasing at a fast pace. As the level of automation increases, the need for high computation also increases, which increases the overall costs. This study aims to address this problem by introducing an integrated E/E architecture where all the computational power is concentrated at one place (or perhaps two or three places to allow for redundancy). This study proposes to introduce a lowcost replacement for the current ECUs with more limited computational power but with generic input/output interfaces.

    This thesis provides the reader with some background of the current E/E architecture of commercial trucks and introduces the reader to ECUs. Additionally, the relevant network architectures and protocols are explained. A potential solution, based upon the centralized computation based E/E architecture and its implementation are discussed followed by a detailed analysis of the replacements for ECUs. The result of this analysis, if adopted, should result in a reduction of manufacturing and design costs, as well as make the production and maintenance process easier. Moreover, this should also have environmental benefits by reducing fuel consumption.

  • 267.
    Tombaz, Sibel
    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.
    On the Design of Energy Efficient Wireless Access Networks2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Wireless access networks today consume 0.5 percent of the global energy. Rapidly growing demand for new services and ubiqutious connectivity, will further increase the energy consumption. This situation imposes a big challenge for mobile operators not only due to soaring cost of energy, but also increasing concern for global warming and sustainable development.

    This thesis focuses on the energy efficiency issue at the system level and studies how to incorporate energy-awareness into the design of future wireless access networks. The main contributions have been given in the areas of energy efficiency assessment, architectural and operational solutions, and total cost of investment analysis.

    The precise evaluation of energy efficiency is the first essential step to determine optimized solutions where metrics and models constitute the two key elements.We show that maximizing energy efficiency is not always equivalent to minimizing energy consumption which is one of the main reasons behind the presented contradictory and disputable conclusions in the literature. Further we indicate that in order to avoid the debatable directions, energy efficient network design problems should be formulated with well defined coverage and capacity requirements. Moreover, we propose novel backhaul power consumption models considering various technology and architectural options relevant for urban and rural environments and show that backhaul will potentially become a bottleneck in future ultra-high capacity wireless access networks.

    Second, we focus on clean-slate network deployment solutions satisfying different quality of service requirements in a more energy efficient manner. We identify that the ratio between idle- and transmit power dependent power consumption of a base station as well as the network capacity requirement are the two key parameters that affect the energy-optimum design.While results show that macro cellular systems are the most energy efficient solution for moderate average traffic density, Hetnet solutions prevail homogeneous deployment due to their ability to increase the capacity with a relatively lower energy consumption and thus enable significant energy savings in medium and high capacity demand regions.

    Moreover, we investigate the energy saving potential of short-term energy aware management approach, i.e., cell DTX, taking advantage of low resource utilization in the current networks arising from strict QoS requirements. With the help of developed novel quantitative method, we show that Cell DTX brings striking reduction in energy consumption and further savings are achievable if the networks are designed taking into account the fact that network deployment and operation are closely related.

    Finally, we develop a general framework for investigating the main cost elements and for evaluating the viability of energy efficient solutions.We first reveal the strong positive impact of spectrum on both energy and infrastructure cost and further indicate that applying sustainable solutions might also bring total cost reduction, but the viability highly depends on unit cost values as well as the indirect cost benefits of energy efficiency.

    Results obtained in this dissertation might provide guidelines for the network designers to achieve future high-capacity and sustainable wireless access networks.

  • 268.
    Tombaz, Sibel
    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.
    Han, San-wook
    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.
    Sung, Ki Won
    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.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Energy Efficient Network Deployment with Cell DTX2014In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 18, no 6, p. 977-980Article in journal (Refereed)
    Abstract [en]

    Cell discontinuous transmission (DTX) is a newfeature that enables sleep mode operations at base station (BS)side during the transmission time intervals (TTIs) when thereis no traffic. In this letter, we analyze the maximum achievableenergy saving of the cell DTX. We incorporate the cell DTXwith a clean-slate network deployment, and obtain optimal BSdensity for lowest energy consumption satisfying a certain qualityof service (QoS) requirement considering daily traffic variation.The numerical result indicates that the fast traffic adaptationcapability of cell DTX favors dense network deployment withlightly loaded cells, which brings about considerable improvementin energy saving.

  • 269.
    Tombaz, Sibel
    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.
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Farias, Fabricio
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. Federal University of Para.
    Fiorani, Matteo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    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.
    Is backhaul becoming a bottleneck for green wireless access networks?2014In: 2014 IEEE International Conference on Communications, ICC 2014, IEEE , 2014, p. 4029-4035Conference paper (Refereed)
    Abstract [en]

    Mobile operators are facing an exponential traffic growth due to the proliferation of portable devices that require a high-capacity connectivity. This, in turn, leads to a tremendous increase of the energy consumption of wireless access networks. A promising solution to this problem is the concept of heterogeneous networks, which is based on the dense deployment of low-cost and low-power base stations, in addition to the traditional macro cells. However, in such a scenario the energy consumed by the backhaul, which aggregates the traffic from each base station towards the metro/core segment, becomes significant and may limit the advantages of heterogeneous network deployments. This paper aims at assessing the impact of backhaul on the energy consumption of wireless access networks, taking into consideration different data traffic requirements (i.e., from todays to 2020 traffic levels). Three backhaul architectures combining different technologies (i.e., copper, fiber, and microwave) are considered. Results show that backhaul can amount to up to 50% of the power consumption of a wireless access network. On the other hand, hybrid backhaul architectures that combines fiber and microwave performs relatively well in scenarios where the wireless network is characterized by a high small-base-stations penetration rate.

  • 270.
    Tombaz, Sibel
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). Ericsson Research, Sweden.
    Sung, Ki Won
    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.
    Han, Sang Wook
    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.
    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 economic viability analysis on energy-saving solutions for wireless access networks2016In: Computer Communications, ISSN 0140-3664, E-ISSN 1873-703X, Vol. 75, p. 50-61Article in journal (Refereed)
    Abstract [en]

    As the energy bill for mobile operators rises with the continuing traffic growth, energy efficiency problems attract an increasing attention in the telecommunication industry. However, the investment for the implementation of any energy-saving solution could be so costly that it may not achieve the total cost reduction. Therefore, the economic viability of the proposed solutions is of substantial importance for the operators in the process of investment decisions. In this paper, we present a methodology for assessing the economic viability of energy-saving solutions. We conduct two case studies using the proposed methodology, and analyze the cost-benefit tradeoff for: (i) hardware upgrade enabling dynamic sleep mode operation at the base stations (BSs), and (ii) energy efficient network deployment minimizing the network energy consumption. Simulation results show that the hardware upgrade can save up to 60% of energy consumption particularly when the high data rate requirement forces low network resource utilization. Consequently, the solution is shown to be increasingly cost effective as the unit energy cost increases. Network deployment optimized for energy efficiency is shown to bring about further energy savings, but it demands denser deployment of BSs. Thus, it is not deemed as economically viable considering today's cost values.

  • 271.
    Tombaz, Sibel
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Sung, Ki Won
    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).
    On metrics and models for energy-efficient design of wireless access networks2014In: IEEE Wireless Communications Letters, ISSN 2162-2337, E-ISSN 2162-2345, Vol. 3, no 6, p. 649-652, article id 6877636Article in journal (Refereed)
    Abstract [en]

    The energy efficiency of wireless access networks has attracted significant interest, due to escalating energy cost and environmental concerns. How energy efficiency should be measured is, however, still disputed in the literature. In this letter, we discuss the impact of performance metrics and energy consumption models in network dimensioning. We argue that, using a popular metric, the number of bits/Joule may give misleading results, unless the capacity and coverage requirements of the system are carefully defined. We also claim that the energy consumption in the backhaul and the idle power of the base stations have to be taken into account. To support our claims, we demonstrate in a simple example how misleading results can be obtained by using flawed performance metrics.

  • 272.
    Tombaz, Sibel
    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.
    Zheng, Zhihao
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    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.
    Energy Efficiency Assessment of Wireless AccessNetworks Utilizing Indoor Base Stations2013In: 2013 IEEE 24th International Symposium on Personal Indoor and Mobile Radio Communications (PIMRC), IEEE conference proceedings, 2013, p. 3105-3110Conference paper (Refereed)
    Abstract [en]

    Energy efficiency in mobile radio networks has recently gained great interest due to escalating energy cost and environmental concerns. Rapidly growing demand for capacity will require denser and denser networks which further increase the energy consumption. In this regard, the deployment of small cells under macro-cellular umbrella coverage appears a promising solution to cope with the explosive demand in an energy efficient manner. In this paper, we investigate the impact of joint macro-and femtocell deployment on energy efficiency of wireless access networks, based on varying area throughput requirements. We take into account the the co-channel interference, fraction of indoor users, femto base station density and backhaul power consumption. It is shown that utilizing indoor base stations provide significant energy savings compared to traditional macro only network in urban areas with medium and high user demand where the gain increases up to 75 percent as more data traffic is offloaded to femtocells.

  • 273.
    Tormo Peiró, Julia Alba
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Spectrum sensing based on specialized microcontroller based white space sensors: Measuring spectrum occupancy using a distributed sensor grid2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The continuing increase in the adoption and use of wireless technology aggravates the problem of spectrum scarcity due to the way we utilize the spectrum. The radio spectrum is a limited resource regulated by governmental agencies according to a fixed spectrum assignment policy. However, many studies show that this fixed radio frequency allocation leads to significant underutilization of the radio spectrum creating artificial scarcity, as most of the allocated spectrum is not used all of the time in every location. To meet services growing demands, efficient use of the spectrum is essential. Therefore, there is a need to estimate the radio spectrum utilization in several locations and during different periods of time in order to opportunistically exploit the existing wireless spectrum. Cognitive radio technology aims to search for those portions of the radio spectrum that are assigned to a specific service, but are unused during a specific time and at specific location in order to share these white spaces and thus to reduce the radio spectrum inefficiency.

    In this thesis, we study spectrum utilization in the frequency range from 790MHz to 925MHz. The spectrum sensing has been realized using a number of specialized microcontroller based white space sensors which utilize energy detection, situated in different locations of a building in Kista, Sweden. The occupancy of the frequency bands in this chunk of the spectrum is quantified as the fraction of samples with a power level greater than a threshold. The results from these spectrum measurements show that a significant amount of spectrum in this scanned range around the building is inefficiently used all the time.

  • 274.
    Umair, Muhammad
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Performance Evaluation and Elastic Scaling of an IP Multimedia Subsystem Implemented in a Cloud2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Network (NGN) technology which enables telecommunication operators to provide multimedia services over fixed and mobile networks. All of the IMS infrastructure protocols work over IP which makes IMS easy to deploy on a cloud platform. The purpose of this thesis is to analysis a novel technique of “cloudifying” the OpenIMS core infrastructure. The primary goal of running OpenIMS in the cloud is to enable a highly available and horizontally scalable Home Subscriber Server (HSS). The resulting database should offer high availability, and high scalability.

    The prototype developed in this thesis project demonstrates a virtualized OpenIMS core with an integrated horizontal scalable HSS. Functional and performance measurements of the system under test (i.e. the virtualized OpenIMS core with horizontally scalable HSS) were conducted. The results of this testing include an analysis of benchmarking scenarios, the CPU utilization, and the available memory of the virtual machines. Based on these results we conclude that it is both feasible and desirable to deploy the OpenIMS core in a cloud.

  • 275.
    Vaggelakos, Konstantinos
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Optimizing Enterprise Resource Planning systems for mobile applications2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Growing enterprises have growing amounts of information. Making sure that this information is easily accessible to its employees is not an easy task. For this task Enterprise Resource Planning (ERP) systems come in handy. However, the ERP systems contain lots of information and may be too complex to handle this information or may be too slow in sharing this information within the organisation. This thesis introduces a new solution for how mobile applications can connect to an ERP system by exploiting database synchronisation, which allows the employees to get the information wherever they are without the need to directly access the ERP system.

    There are three important questions in this thesis: how the ERP works, how to build a mobile application and, how to build a back end? By combining answers to these questions a whole system is built which is production ready and can copy data between the ERP system and the back end and show the information in a mobile application. The overarching goals were to build a system that could extract data from the ERP system into a proprietary back end and a mobile application that could synchronise with the back end. However, synchronisation between the mobile application and the back end was not implemented due to lack of time. The back end had to be able to scale up to 500 concurrent users and respond within 3 seconds, both of these goals were achieved. The mobile application that was built to display the information to the end user was built with usability in mind, since Netlight wanted a straightforward application that anyone could use. The mobile application was shown to have good usability.

    The results of this thesis project show that building systems around ERPs, instead of inside them, gives these systems the ability to scale, improved the implementation time, and reduced the company’s maintenance efforts.

  • 276.
    Valdenebro González, Fernando
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Energy-efficient enhancements for IEEE 802.11 WLANs: On the way to enable Cellular/Wi-Fi networks interworking2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Globally, the number of mobile broadband subscriptions is growing and the amount of mobile data traffic is expected to continue to grow rapidly. In the next five years the number of smartphone subscriptions is expected to more than double, while the amount of mobile traffic per active subscription per month of these subscribers is expected to nearly quadruple.

    As a consequence, mobile network operators (MNOs) aim to increase radio network capacity and coverage through heterogeneous deployments. In such heterogeneous networks, wireless local area networks (WLANs) are integrated with wireless wide area networks (WWANs), and there exist a tight interaction between them.

    The almost-ubiquitous support for IEEE802.11 WLANs (usually referred to as Wi-Fi®) makes this radio access technology a potential integrated component of near-future mobile broadband. With Wi-Fi completely integrated into mobile access, MNOs would optimize user experience and use of resources by controlling device’s choice of connectivity. In addition to guaranteeing the best user experience, optimal use of access networks should care about energy-efficiency in order to extend device’s battery life.

    However, the performance of Wi-Fi is far from meet neither energy-efficiency nor quality of service (QoS) user’s requirements. This radio access technology employs an energy-consuming medium access control (MAC) protocol that wastes both bandwidth and device’s energy resources. Therefore, enhanced MAC protocols, cleverly combined with standardized power saving mechanisms such as automatic power save delivery (APSD), would improve both energy-efficiency and QoS in order to enhance WLANs performance and meet user’s expectations.

    In addition, current WLAN discovery mechanisms neither meet requirements of the integrated scenario. Handover operations must be improved in terms of energy efficiency and latency. Consequently, enhanced handover schemes should reduce overall device’s energy consumption during the process, and enable seamless handover between Wi-Fi APs and between cellular/Wi-Fi networks.

    During this thesis project, the main challenges of Wi-Fi towards its integration into mobile access broadband have been analyzed. Consequently, a solution has been designed in order to address the identified challenges, which have been introduced in the previous paragraphs. The solution consists of enhancements for IEEE 802.11 WLANs based on current standards that achieve energy-efficiency and QoS, and facilitate Wi-Fi/cellular networks interworking. Finally, a custom-designed simulator has been used to evaluate the proposed solution.

  • 277.
    Vargas-Orellana, Julio
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    A Distributed Approach for Global Product Lifecycle Management2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Product Lifecycle Management (PLM) is a holistic approach for managing product information throughout its life cycle. It integrates different concepts that have emerged due to changes in the manufacturing process as a result of globalization, increased competition, demand for more innovative products, and other reasons. These changes have leaded to a shift from a model with a single-location for product development to a model in which a complex network of specialized companies collaborate.

    This global collaborative PLM implies that companies from different parts of the world work together and must share information; hence the underlying PLM system is required to facilitate data management throughout this collaborative process. In addition, it is also necessary to address the challenges due to the new model being a distributed activity, as today this PLM system is a specialized distributed system.

    Maintaining data consistency can be challenging because collaborators can use heterogeneous PLM systems together with their own databases. The later cannot be shared due to the risks of exposing their knowledge base and business processes. Another consideration in global collaboration is that data is transmitted to remote locations. As a result network latency can be large; this can cause problems particularly when large files are exchanged, such as may be the case for CAD design models.

    This thesis proposes a solution enabling a global PLM which addresses the challenges described above. The approach consists of connecting collaborators’ nodes in a network that is constructed by grouping them with respect to intra-site latency. Each group implements a coordination mechanism based on the election of a node which is subsequently in charge of coordinating data access. The groups communicate via a publish-subscribe communication pattern, publishing and subscribing to events related to the resources being shared. The integration of the solution is through a Service-oriented Architecture (SOA) implementing web services that can be consumed by a PLM system. A prototype has been implemented and its applicability is analysed by evaluating its functionality in a collaborative scenario based on the Aras Innovator PLM platform.

    The evaluation was made by simulating the solution proposed and comparing it with a centralized approach. The results particularly showed that the proposed solution could reduce the intra-latency compared to a centralized approach if the collaborators are organized in collaborative groups, that exchange most of the information inside the group rather than intergroup.

  • 278. Verenzuela, D.
    et al.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). Freelinguist.com, Sweden.
    Scalable D2D Communications for Frequency Reuse >> 1 in 5G2017In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 16, no 6, p. 3435-3447, article id 7891615Article in journal (Refereed)
    Abstract [en]

    Proximity-based applications are becoming fast growing markets suggesting that device-to-device (D2D) communications is becoming an essential part of the future mobile data networks. We propose scalable admission and power control methods for D2D communications underlay cellular networks to increase the reuse of frequency resources and thus network capacity while maintaining QoS to all users. In practice, as D2D communications will generate a new layer of interference, it is essential to take D2D interference into account in inter-cell interference coordination for multi-cell communications. The aim of the proposed methods is to maximize the number of D2D links under QoS constraints, therefore maximizing network frequency reuse in a practical 5G multi-cell environment. Different schemes are designed for applications that have different levels of complexity and availability of channel state information. Numerical results show that by using D2D and the proposed multi-cell interference coordination and low power transmission method, the network spectral efficiency can be increased by as much as ten times, while low outage probability can be assured to provide QoS for all users.

  • 279. Verenzuela, Daniel
    et al.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Scalable Device-to-Device Communications For Frequency Reuse>> 1Manuscript (preprint) (Other academic)
    Abstract [en]

    Proximity based applications are becoming fast growing markets suggesting that Device-to-Device (D2D) communications is becoming an essential part of future mobile data networks. We propose scalable admission and power control methods for D2D communications underlay cellular networks to increase the reuse of frequency resources and thus network capacity while maintaining QoS to all users. The aim of the proposed methods is to maximize the number of D2D links under QoS constraints, therefore maximizing network frequency reuse, while considering different levels of complexity an d available channel state information (CSI) in a multi-cell environment. Numerical results show that by using D2D and the proposed multi-cell interference coordination and low power transmission method, the network spectral efficiency can be increased by as much as ten times, while low outage probability can be assured to provided QoS for all users.

  • 280.
    Viggiani, Fabio
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Design and implementation of a non-aggressive automated penetration testing tool: An approach to automated penetration testing focusing on stability and integrity for usage in production environments2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The focus of this Master’s thesis project is automated penetration testing. A penetration test is a practice used by security professionals to assess the security of a system. This process consists of attacking the system in order to reveal flaws.  Automating the process of penetration testing brings some advantages, the main advantage being reduced costs in terms of time and human resources needed to perform the test. Although there exist a number of automated tools to perform the required procedures, many security professionals prefer manual testing. The main reason for this choice is that standard automated tools make use of techniques that might compromise the stability and integrity of the system under test. This is usually not acceptable since the majority of penetration tests are performed in an operating environment with high availability requirements.

    The goal of this thesis is to introduce a different approach to penetration testing automation that aims to achieve useful test results without the use of techniques that could damage the system under test. By investigating the procedures, challenges, and considerations that are part of the daily work of a professional penetration tester, a tool was designed and implemented to automate this new process of non-aggressive testing.

    The outcome of this thesis project reveals that this tool is able to provide the same results as standard automated penetration testing procedures. However, in order for the tool to completely avoid using unsafe techniques, (limited) initial access to the system under test is needed.

  • 281.
    Vondra, Michal
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Dinc, Ergin
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Prytz, Mikael
    Frodigh, Magnus
    Dominic, Schupke
    Nilsson, Mats
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Hofmann, Sandra
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Performance Study on Seamless DA2GC for Aircraft Passengers Toward 5G2017In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 55, no 11, p. 194-201Article in journal (Refereed)
    Abstract [en]

    Mobile users seek for ubiquitous broadband connectivity even during a flight above the clouds. As many passengers are expected to be connected to high-speed Internet, robust and high-capacity direct air-to-ground communication (DA2GC) to connect the aircraft with the ground cellular network is particularly attractive. In this paper, we assess the capacity limitations of DA2GC link provided to an aircraft by employing currently available 4G radio technologies. Further, we study different capacity enhancement techniques toward 5G such as an implementation of Multi-User Multiple Input Multiple Output (MU-MIMO) or coordinated beamsteering to improve DA2GC capacity. We also compare DA2GC performance with connectivity offered by satellites. According to our results, DA2GC network extended for techniques toward 5G can improve capacity available per aircraft nearly by 100 Mb/s in comparison with the 4G DA2GC network, assuming 20 MHz bandwidth is exploited. Although the maximal capacity provided by the 5G DA2GC network and satellite communication is the same, satellite communication exhibits only 40 Mb/s for 10 000 deployed satellites in average. To incite future investigation in this field, this paper also outlines open challenges and research directions toward more efficient DA2GC. 

  • 282.
    Wang, Huajun
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Hossain, Masum M.Aftab
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Cloud RAN architectures with optical and mm-Wave transport technologies2017In: 2017 19th International Conference on Transparent Optical Networks (ICTON), IEEE Computer Society, 2017, article id 8025007Conference paper (Refereed)
    Abstract [en]

    Cloud RAN has been regarded as a promising architecture for 5G mobile networks in terms of combination of implementing the very tight radio coordination schemes and sharing baseband processing and cooling system resources. However, the high capacity and stringent delay requirement for the fronthaul, the segment of the network between Baseband Units (BBU) and Remote Radio Heads (RRH) is one of the biggest barriers to larger deployments. To relax these constraints, physical layer functions can be split and centralized partially. In this paper, under one specific case scenario with the fixed number of LTE base stations, we calculate the transport capacity requirement for different physical layer function splitting solutions and adopt different transport technologies, i.e. Ethernet Passive Optical Network (EPON), Time-Wavelength Division Multiplexing PON, (TWDM-PON) and millimeter Wave (mm-Wave). We develop an end-to end power consumption model where the total power consumption is calculated by adding up the power utilized by RRHs, transport network and baseband processing. TWDM-PON shows better energy performance as fronthaul network when the capacity requirement is high, compared to EPON. The mm-Wave fronthaul is a better solution in terms of saving fiber and flexibility of deployment but comparatively more energy consuming.

  • 283.
    Wang, Willy
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Evaluating the use of PXI modules in tests of a radio base station2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis project was carried out at the electromagnetic compatibility (EMC) department at Ericsson AB. One of the department’s goals is to seek a possible replacement to the box test instruments by utilizing PCI extension for instrumentation (PXI) modules. The main objective of this project is to evaluate how different PXI modules work during testing of a radio base station (RBS), in terms of performance, test time, and cost. A downlink decoder was implemented in LabVIEW with an extension called MathScript and several software test solutions were examined to measure error vector magnitude (EVM), frequency error, and power, and to perform parallel measurements in a multiple radio access technology (multi-RAT) test configuration. Moreover, several uplink tests were performed to decide if PXI modules are a suitable substitute for the previous box based test instruments. The findings from this study show that PXI modules can replace the previous box based test instruments. However it was concluded that not all areas can be covered and not all discrete test instrument can (yet) be replaced. Future work should complete the downlink decoder implementation in the field programmable gate array (FPGA) level in order to further improve the performance further. Future work should also examine if it is possible to replace all of the discrete test instruments with PXI modules.

  • 284. Wang, X.
    et al.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Wang, L.
    Tornatore, M.
    Chung, H. S.
    Lee, H. H.
    Park, S. M.
    Mukherjee, B.
    Virtualized Cloud Radio Access Network for 5G Transport2017In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 55, no 9, p. 202-209, article id 8030505Article in journal (Refereed)
    Abstract [en]

    Current radio access networks (RANs) need to evolve to handle diverse service requirements coming from the growing number of connected devices and increasing data rates for the upcoming 5G era. Incremental improvements on traditional distributed RANs cannot satisfy these requirements, so the novel and disruptive concept of a cloud RAN (CRAN) has been proposed to decouple digital units (DUs) and radio units (RUs) of base stations (BSs), and centralize DUs into a central office, where virtualization and cloud computing technologies are leveraged to move DUs into the cloud. However, separating RUs and DUs requires low-latency and high-bandwidth connectivity links, called "fronthaul," as opposed to traditional backhaul links. Hence, design of the 5G transport network, that is, the part of the network that carries mobile data traffic between BSs and the core network and data centers, is key to meet the new 5G mobile service requirements and effectively transport the fronthaul traffic. Today, consensus is yet to be achieved on how the fronthaul traffic will be transported between RUs and DUs, and how virtualization of network resources will occur from a radio network segment to the centralized baseband processing units. In this article, we present a new 5G architecture, called virtualized cloud radio access network (V-CRAN), moving toward a cell-less 5G network architecture. We leverage the concept of a virtualized BS (V-BS) that can be optimally formed by exploiting several enabling technologies such as software defined radio (SDR) and coordinated multipoint (CoMP) transmission/reception. A V-BS can be formed on a per-cell basis or per-user basis by allocating virtualized resources on demand. For the fronthaul solution, our approach exploits the passive optical network (PON), where a wavelength can be dynamically assigned and shared to form a virtualized passive optical network (VPON). Several use cases of the V-CRAN are presented to show how network architecture evolution can enhance system throughput, energy efficiency, and mobility management.

  • 285. Wang, X.
    et al.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Wang, L.
    Tornatore, M.
    Zhao, Y.
    Chung, H. S.
    Lee, H. H.
    Park, S.
    Mukherjee, B.
    Joint allocation of radio and optical resources in virtualized cloud RAN with CoMP2017In: 2016 IEEE Global Communications Conference, GLOBECOM 2016 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2017, article id 7841923Conference paper (Refereed)
    Abstract [en]

    5G Radio Access Networks (RANs) are supposed to increase their capacity by 1000x to handle growing number of connected devices and increasing data rates. The concept of cloud-RAN (CRAN) has been recently proposed to decouple digital units (DUs) and radio units (RUs) of base stations (BSs), and centralize DUs into central offices. CRAN can ease the implementation of advanced radio coordination techniques, e.g., Coordinated Multi-Point (CoMP) Transmission/Reception, to enhance its system throughput. However, separating DUs and RUs, and implementing CoMP in CRAN require low-latency and high-bandwidth connectivity links, called "fronthaul". Today, consensus has not yet been achieved on how BSs, fronthaul, and central offices will be orchestrated to enhance the system throughput. In this study, we present a CRAN over Passive Optical Network (PON) architecture called virtualized-CRAN (V-CRAN). V-CRAN leverages the concept of virtualized PON (VPON) that can dynamically associate any RU to any DU so that several RUs can be coordinated by the same DU, and the concept of virtualized BS (V-BS) that can jointly transmit common signals from multiple RUs to a user. We propose a novel mathematical model based on constraint programming for joint allocation of radio, optical network, and baseband processing resources to enhance RAN throughput, and we solve it by optimally forming VPONs and V-BSs. Comprehensive simulations show that V-CRAN can enhance the system throughput and the efficiency of resource utilization.

  • 286. Wang, X.
    et al.
    Wang, L.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Tornatore, M.
    Figueiredo, G. B.
    Chung, H. S.
    Lee, H. H.
    Park, S.
    Mukherjee, B.
    Handover reduction in virtualized cloud radio access networks using TWDM-PON fronthaul2016In: Journal of Optical Communications and Networking, ISSN 1943-0620, E-ISSN 1943-0639, Vol. 8, no 12, p. B124-B134Article in journal (Refereed)
    Abstract [en]

    To meet challenging 5G capacity requirements, operators are densifying their cellular networks by deploying additional small cells to cover hot spots, and such an increase in the number and density of cells may result in excessive numbers of handovers. In this study, we propose a handover reduction mechanism implemented in a cloud radio access network (CRAN) by exploiting the high capacity of an optical access network serving as a "fronthaul." CRAN has been proposed as a 5G radio access network architecture, where the digital unit (DU) of a conventional base station (BS) is separated from the radio unit (RU) and moved to the "cloud" (DU-cloud) for better mobility management and cost saving. Separating RUs and DUs requires a low-latency and high-bandwidth 5G transport network to handle "fronthaul" traffic, for which optical access is an excellent choice. Here, we present a new 5G architecture, called virtualized-CRAN (V-CRAN), moving toward a cell-less 5G mobile network architecture. We leverage the concept of a "virtualized-BS" (V-BS) that can be formed by exploiting several enabling technologies such as software-defined radio and coordinated multipoint transmission/reception. A V-BS can be formed on a per-user basis by allocating virtualized resources on demand so that common signals can be jointly transmitted from multiple RUs to the user without triggering handover. We first model the handover reduction optimization problem for a scenario where future mobility information is known, and then propose a suite of algorithms for a scenario where future information is unknown. Simulation results show that V-CRAN can enhance the throughput of users at the cell-edge, as well as significantly reduce the number of handovers, handover delay, and failure rate.

  • 287. Wang, X.
    et al.
    Wang, L.
    Elayoubi, S. E.
    Conte, A.
    Mukherjee, B.
    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.
    Centralize or distribute?: A techno-economic study to design a low-cost cloud radio access network2017In: 2017 IEEE International Conference on Communications, ICC 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, article id 7996771Conference paper (Refereed)
    Abstract [en]

    Cloud radio access network (CRAN) has been proposed as a promising evolution of mobile network architecture where baseband processing functions of a base station are split/decoupled from the radio unit (RU) and centralized. However, rigid bandwidth and latency requirements are incurred by fronthaul, i.e., transport link, which connects RU to the central cloud. Therefore, new functional splits are discussed for CRAN with dual-site processing, which we call Hybrid-RAN (H-RAN), where some functions remain distributed while others are centralized. In this work, from a perspective of minimizing the total cost of ownership (TCO) for H-RAN, we present a techno-economic study to find the optimal functional splits for a base station (BS), with a given configuration. A configuration of a BS represents frequency layers, carrier bandwidths, and MIMO schemes, associated with different frequency bands. For each functional split, we present a model to calculate the requirement of computational resources and fronthaul bandwidth. We formulate a TCO minimization model using constraint programming. Numerical results show that the optimal functional split depends on BS configuration, fiber ownership, and data transmission direction. H-RAN with optimal functional split can achieve lower TCO than both classical Distributed RAN and CRAN.

  • 288.
    Wang, Y.
    et al.
    Xi'an Jiaotong University.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Wang, X.
    Xi'an Jiaotong University.
    A Non-cooperative Scheme for SFR-Based Power Control in LTE Networks2014Conference paper (Refereed)
    Abstract [en]

    We propose a non-cooperative power allocation scheme for cellular systems using soft frequency reuse and in the power control, each user selfishly maximizes its utility.To find the tradeoff between QoS satisfaction and energy consumption, we design a utility function that considers both QoS requirements and the cost. We then show there exists a Nash equilibrium and provide conditions to assure its uniqueness. This scheme has limited signaling overhead and only pricing information needs to be exchanged among cells. Simulation results show that this scheme improves throughput and coverage performance compared with conventional SFR schemes.

  • 289. Wang, Y.
    et al.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Wang, X.
    Joint Interference Mitigation and Power Allocation for Multi-Cell LTE Networks: A Non-Cooperative Game Approach2014In: 2014 IEEE 80th Vehicular Technology Conference (VTC Fall), IEEE , 2014, p. 6966031-Conference paper (Refereed)
    Abstract [en]

    We propose a non-cooperative game-theoretic power allocation (NGPA) scheme for interference mitigation in long term evolution (LTE) uplink in this paper. We first set up the interference model employing conventional soft frequency reuse (SFR) scheme for inter-cell interference coordination (ICIC) in a nineteen-cell LTE network. Since each user may selfishly maximize its own performance in power allocation, we design a utility function that considers both quality of service (QoS) satisfaction and energy consumption. We then investigate the existence of Nash equilibrium and derive a sufficient condition to assure its uniqueness. Simulation results show that the proposed scheme improves throughput and coverage performances compared with conventional SFR schemes. Moreover, this scheme only requires limited signaling overhead among cells, which can be readily implemented in a distributed manner for practical systems.

  • 290.
    Wang, Yuanshuang
    et al.
    Xi'an Jiaotong University.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Wang, Xia
    Xi'an Jiaotong University.
    An Energy-Efficient Non-Cooperative Game Approach for Channel-Aware Distributed Medium Access Control2014In: 2014 IEEE 80th Vehicular Technology Conference (VTC Fall), IEEE , 2014, p. 1-6Conference paper (Refereed)
    Abstract [en]

    In this paper, an energy-efficient non-cooperative game approach is proposed for channel-aware distributed medium access control (EN-CDMAC) in slotted-Aloha systems, where users act selfishly to improve their own utilities. To resolve the network contention in a distributed manner, the capture model is employed and a pricing-based non-cooperative game scheme is designed to enable selfish users effectively achieve multi-user diversity by adjusting their equilibrium thresholds while guaranteeing fairness by the pricing mechanism. Then the existence of Nash equilibrium is proved, and the necessary and sufficient condition is derived to ensure its uniqueness. Furthermore, the equilibrium stability is investigated with stochastic process theory. Simulation results show that the proposed approach significantly improves the network throughput and delay performance without sacrificing energy efficiency compared to the conventional slotted-Aloha scheme. In particular, the proposed approach is more applicable for high-load systems.

  • 291.
    Weidenhielm, Lars
    et al.
    Karolinska Institutet at Karolinska University Hospital Solna.
    Olivecrona, Henrik
    Karolinska Institutet, Sweden.
    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.
    Prosthetic liner wear in total hip replacement: a longitudinal 13-year study with computed tomography.2018In: Skeletal Radiology, ISSN 0364-2348, E-ISSN 1432-2161, p. 1-5Article in journal (Refereed)
    Abstract [en]

    This case report follows a woman who had a total hip replacement in 1992 when she was 45 years old. Six serial computed tomography (CT) examinations over a period of 13 years provided information that allowed her revision surgery to be limited to liner replacement as opposed to replacement of the entire prosthesis. Additionally, they provided data that ruled out the presence of osteolysis and indeed none was found at surgery. In 2004, when the first CT was performed, the 3D distance the femoral head had penetrated into the cup was determined to be 2.6 mm. By 2017, femoral head penetration had progressed to 5.0 mm. The extracted liner showed wear at the thinnest part to be 5.5 mm, as measured with a micrometer. The use of modern CT techniques can identify problems, while still correctable without major surgery. Furthermore, the ability of CT to assess the direction of wear revealed that the liner wear changed from the cranial to dorsal direction.

  • 292. Wu, J.
    et al.
    Zhou, S.
    Niu, Z.
    Liu, C.
    Yang, P.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Traffic-Aware Data and Signaling Resource Management for Green Cellular Networks2014Conference paper (Refereed)
    Abstract [en]

    The increasing traffic demands bring heavy load toboth the data and control planes of cellular networks, along withsubstantial energy consumption. To solve the issue, new networkarchitecture that separates signaling and data has been proposedin literature for future green cellular networks. In this paper, weanalyze the data and signaling resource configuration problemin this new network architecture. We find the optimal resourcepartitioning parameters to optimize the blocking performanceand to minimize the overall network power consumption witha blocking probability constraint. More specifically, we adopttraffic-aware resource allocation between the data and signalingbase stations (BSs) to improve network access capability whilereducing the overall network power consumption. Two typesof resource partitioning patterns, complete partitioning andpartial partitioning, are studied. Numerical results show thatgreat energy-saving gain can be achieved compared with thetraditional fixed and traffic-proportional resource partitioningpatterns. Moreover, power consumption and blocking performancetradeoffs are explored, based on which the appropriateresource partitioning pattern can be chosen according to differentquality of service (QoS) requirements.

  • 293.
    Xiong, Xuelin
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    SCTP and Diameter Parameters for High Availability in LTE Roaming2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

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

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

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

  • 294.
    Yalew, Sileshi Demesie
    et al.
    KTH, School of Information and Communication Technology (ICT), Software and Computer systems, SCS. Universidade de Lisboa, Portugal.
    Maguire Jr., Gerald Q.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Correia, Miguel
    Universidade de Lisboa, Portugal.
    Light-SPD: a platform to prototype secure mobile applications2016In: Proceedings of the 1st ACM Workshop on Privacy-Aware Mobile Computing (PAMCO '16), New York, NY, USA: Association for Computing Machinery (ACM), 2016, p. 11-20Conference paper (Refereed)
    Abstract [en]

    Securely storing sensitive personal data is critical for protecting privacy. Currently, many persons use smartphones to store their private data. However, smartphones suffer from many security issues. To overcome this situation, the PCAS project is designing a secure personal storage device called the Secure Portable Device (SPD), to be attached to a smartphone for securely storing sensitive personal data. However, this device is unavailable, closed, and expensive to deploy for prototyping applications. We propose a platform that emulates the SPD and the smartphone using a board with an ARM processor with the TrustZone security extension. This platform is open, inexpensive, and secure. A payment application is used as an example to show the platform's capabilities. As a proof-of-concept, we implemented this platform and provide a performance evaluation using a i.MX53 board.

  • 295.
    Yalew, Sileshi Demesie
    et al.
    KTH, School of Information and Communication Technology (ICT), Software and Computer systems, SCS.
    Maguire Jr., Gerald Q.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Haridi, Seif
    KTH, School of Information and Communication Technology (ICT), Software and Computer systems, SCS.
    Correia, Miguel
    INESC-ID & Instituto Superior Tecnico, Portugal.
    DroidPosture: A Trusted Posture Assessment Service for Mobile Devices2017In: Proceedings of the 13th IEEE International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob), Institute of Electrical and Electronics Engineers (IEEE), 2017, p. 1-8Conference paper (Refereed)
    Abstract [en]

    Mobile devices such as smartphones are becoming the majority among computing devices. Currently, millions of persons use such devices to store and process personal data. Unfortunately, smartphones running Android are increasingly being targeted by hackers and infected with malware. Antimalware software is being used to address this situation, but it may be subverted by the same malware it aims to detect.

    We present DROIDPOSTURE, a posture assessment service for Android devices. This service aims to securely evaluate the level of trust we can have on a device (assess its posture) even if the mobile OS is compromised. For that to be possible, DROIDPOSTURE is protected using TrustZone, a security extension for ARM processors. DROIDPOSTURE is configurable with a set of application and kernel analysis mechanisms that enable detecting malicious applications and rootkits. We implemented a DROIDPOSTURE prototype using a hardware board with an ARM processor with TrustZone, and evaluated its performance and security.

  • 296.
    Yalew, Sileshi Demesie
    et al.
    KTH, School of Information and Communication Technology (ICT), Software and Computer systems, SCS.
    Maguire Jr., Gerald Q.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Haridi, Seif
    KTH, School of Information and Communication Technology (ICT), Software and Computer systems, SCS.
    Correia, Miguel
    Universidade de Lisboa, Portugal..
    T2Droid: A TrustZone-Based Dynamic Analyser for Android Applications2017In: Proceedings - 16th IEEE International Conference on Trust, Security and Privacy in Computing and Communications, 11th IEEE International Conference on Big Data Science and Engineering and 14th IEEE International Conference on Embedded Software and Systems, Trustcom/BigDataSE/ICESS 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, p. 240-247, article id 8029446Conference paper (Refereed)
    Abstract [en]

    Android has become the most widely used mobile operating system (OS) in recent years. There is much research on methods for detecting malicious Android applications. Dynamic analysis methods detect such applications by evaluating their behaviour during execution. However, such mechanisms may be ineffective as malware is often able to disable antimalware software. This paper presents the design of T2DROID, a dynamic analyser for Android that uses traces of Android API function calls and kernel syscalls, and that is protected from malware by leveraging the ARM TrustZone security extension. In our experimental evaluation T2DROID achieved accuracy and precision of 0.98 and 0.99, respectively, with a kNN classifier.

  • 297.
    Yalew, Sileshi Demesie
    et al.
    Univ Lisbon, Inst Super Tecn, INESD ID, Lisbon, Portugal.
    Mendonca, Pedro
    Maguire Jr., Gerald Q.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Haridi, Seif
    KTH, School of Information and Communication Technology (ICT).
    Correia, Miguel
    TruApp: A TrustZone-based Authenticity Detection Service for Mobile Apps2017In: 2017 IEEE 13TH INTERNATIONAL CONFERENCE ON WIRELESS AND MOBILE COMPUTING, NETWORKING AND COMMUNICATIONS (WIMOB), IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    In less than a decade, mobile apps became an integral part of our lives. In several situations it is important to provide assurance that a mobile app is authentic, i.e., that it is indeed the app produced by a certain company. However, this is challenging, as such apps can be repackaged, the user malicious, or the app tampered with by an attacker. This paper presents the design of TRUAPP, a software authentication service that provides assurance of the authenticity and integrity of apps running on mobile devices. TRUAPP provides such assurance, even if the operating system is compromised, by leveraging the ARM TrustZone hardware security extension. TRUAPP uses a set of techniques (static watermarking, dynamic watermarking, and cryptographic hashes) to verify the integrity of the apps. The service was implemented in a hardware board that emulates a mobile device, which was used to do a thorough experimental evaluation of the service.

  • 298.
    Yang, Dekun
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Investigation of a new integration test environment: Facilitating offline debugging of Hardware-in-the-Loop2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

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

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

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

  • 299.
    Yang, Yanpeng
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    A study on the deployment and cooperative operation of ultra-dense networks2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The traffic volume in wireless communication has grown dramatically in the last decade and is predicted to keep increasing in the future. In this thesis, we focus on the densification dimension for capacity improvement, which has been proved to be the most effective in the past. The current gain of network densification mainly comes from cell splitting, thereby serving more user equipments (UEs) simultaneously. This trend will decelerate as base station (BS) density gets closer to or even surpass UE density which forms an ultra-dense network (UDN). Thus, it is crucial to understand the behavior of ultra-densification for future network provisioning.

     

    We start from comparing the effectiveness of densification with spectrum expansion and multi-antenna systems. Our findings show that deploying more BSs provides a substantial gain in sparse network but the gain decreases progressively in a UDN. The diminishing gain appears in a UDN make us curious to know if there exists a terminal on the way of densification. Such uncertainty leads to the study on the asymptotic behavior of densification. We incorporate a sophisticated bounded dual-slope path loss model and practical UE densities in our analysis. By using stochastic geometry, we derive the expressions and prove the convergence of the coverage probability of a typical UE and network area spectral efficiency (ASE). Considering the large portion of dormant BSs in a UDN, it is an interesting question whether we can utilize these dormant BSs to improve system performance is an interesting question. To this end, we employ joint transmission (JT) techniques into a UDN. Two types of cooperation schemes are investigated: non-coherent JT and coherent JT depending on the availability of channel state information (CSI). Our results reveal that non-coherent JT is not beneficial in a UDN while coherent JT are able to increase UE spectral efficiency (SE) depending on the environmental parameters.

  • 300.
    Yang, Yanpeng
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Hossein, Shokri-Ghadikolaei
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    Petrova, Marina
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Ki Won, Sung
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Fast and Reliable Initial Access with Random Beamforming for mmWave NetworksManuscript (preprint) (Other academic)
    Abstract [en]

    Millimeter-wave (mmWave) communications rely on directional transmissions to overcome severe path loss. Nevertheless, the use of narrow beams complicates the initial access procedure and increase the latency as the transmitter and receiver beams should be aligned for a proper link establishment. In this paper, we investigate the feasibility of random beamforming for the cell-search phase of initial access. We develop a stochastic geometry framework to analyze the performance in terms of detection failure probability and expected latency of initial access as well as total data transmission. Meanwhile, we compare our scheme with the widely used exhaustive search and iterative search schemes, in both control plane and data plane. Numerical results show that, compared to the other two schemes, random beamforming can substantially reduce the latency of initial access with comparable failure probability in dense networks. We show that the gain of the random beamforming is more prominent in light traffics and low-latency services. Our work demonstrates that developing complex cell-discovery algorithms may be unnecessary in dense mmWave networks and thus shed new lights on mmWave network design.

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