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  • 151.
    Ali, Muhammad Usman
    Blekinge Institute of Technology, School of Computing.
    Cloud Computing as a Tool to Secure and Manage Information Flow in Swedish Armed Forces Networks2012Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    In the last few years cloud computing has created much hype in the IT world. It has provided new strategies to cut down costs and provide better utilization of resources. Apart from all drawbacks, the cloud infrastructure has been long discussed for its vulnerabilities and security issues. There is a long list of service providers and clients, who have implemented different service structures using cloud infrastructure. Despite of all these efforts many organizations especially with higher security concerns have doubts about the data privacy or theft protection in cloud. This thesis aims to encourage Swedish Armed Forces (SWAF) networks to move to cloud infrastructures as this is the technology that will make a huge difference and revolutionize the service delivery models in the IT world. Organizations avoiding it would lag behind but at the same time organizations should consider to adapt a cloud strategy most reliable and compatible with their requirements. This document provides an insight on different technologies and tools implemented specifically for monitoring and security in cloud. Much emphasize is given on virtualization technology because cloud computing highly relies on it. Amazon EC2 cloud is analyzed from security point of view. An intensive survey has also been conducted to understand the market trends and people’s perception about cloud implementation, security threats, cost savings and reliability of different services provided.

  • 152.
    Ali, Sajjad
    et al.
    Blekinge Institute of Technology, School of Computing.
    Ali, Asad
    Blekinge Institute of Technology, School of Computing.
    Performance Analysis of AODV, DSR and OLSR in MANET2010Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    A mobile ad hoc network (MANET) consists of mobile wireless nodes. The communication between these mobile nodes is carried out without any centralized control. MANET is a self organized and self configurable network where the mobile nodes move arbitrarily. The mobile nodes can receive and forward packets as a router. Routing is a critical issue in MANET and hence the focus of this thesis along with the performance analysis of routing protocols. We compared three routing protocols i.e. AODV, DSR and OLSR. Our simulation tool will be OPNET modeler. The performance of these routing protocols is analyzed by three metrics: delay, network load and throughput. All the three routing protocols are explained in a deep way with metrics. The comparison analysis will be carrying out about these protocols and in the last the conclusion will be presented, that which routing protocol is the best one for mobile ad hoc networks.

  • 153.
    Ali, Wajahat
    et al.
    Blekinge Institute of Technology, School of Computing.
    Muhammad, Asad
    Blekinge Institute of Technology, School of Computing.
    Response Time Effects on Quality of Security Experience2012Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    The recent decade has witnessed an enormous development in internet technology worldwide. Initially internet was designed for applications such as Electronic Mail and File Transfer. With technology evolving and becoming popular, people use internet for e-banking, e-shopping, social networking, e-gaming, voice and a lot of other applications. Most of the internet traffic is generated by activities of end users, when they request a specific webpage or web based application. The high demand for internet applications has driven service operators to provide reliable services to the end user and user satisfaction has now become a major challenge. Quality of Service is a measure of the performance of a particular service. Quality of Experience is a subjective measure of user’s perception of the overall performance of network. The high demand for internet usage in everyday life has got people concerned about security of information over web pages that require authentication. User perceived Quality of Security Experience depends on Quality of Experience and Response Time for web page authentication. Different factors such as jitter, packet loss, delay, network speed, supply chains and the type of security algorithm play a vital role in the response time for authentication. In this work we have tried to do qualitative and quantitative analysis of user perceived security and Quality of Experience with increasing and decreasing Response Times towards a web page authentication. We have tried to derive a relationship between Quality of Experience of security and Response Time.

  • 154.
    Alibabaei, Navid
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Wireless Mesh Networks: a comparative study of Ad-Hoc routing protocols toward more efficient routing2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Each day, the dream of seamless networking and connectivity everywhere is getting closer to become a reality. In this regard, mobile Ad-Hoc networks (MANETs) have been a hot topic in the last decade; but the amount of MANET usage nowadays confines to a tiny percentage of all our network connectivity in our everyday life, which connectivity through infrastructured networks has the major share. On the other hand, we know that future of networking belongs to Ad-Hocing , so for now we try to give our everyday infrastructure network a taste of Ad-Hocing ability; these types of networks are called Wireless Mesh Networks (WMN) and routing features play a vital role in their functionality. In this thesis we examine the functionality of 3 Ad-Hoc routing protocols known as AODV, OLSR and GRP using simulation method in OPNET17.5. For this goal we set up 4 different scenarios to examine the performance of these routing protocols; these scenarios vary from each other in amount of nodes, background traffic and mobility of the nodes. Performance measurements of these protocols are done by network throughput, end-end delay of the transmitted packets and packet loss ratio as our performance metrics. After the simulation run and gathering the results we study them in a comparative view, first based on each scenario and then based on each protocol. For conclusion, as former studies suggest AODV, OLSR and DRP are among the best routing protocols for WMNs, so in this research we don’t introduce the best RP based on the obtained functionality results, instead we discuss the network conditions that each of these protocols show their best functionality in them and suggest the best routing mechanism for different networks based on the analysis from the former part.  

  • 155.
    Alija Fuertes, Miguel Jesús
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Industrial Economics and Management (Div.).
    Mobile Devices: Dominant Design as a Goal2013Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Since the beginning of the smartphones in the 80s, the mobile device market has grown and evolved towards devices connected everywhere, with hardware more and more close to computers and laptops than a classic mobile telephone. Nowadays, this market seems to be crowded and some companies seem not to know exactly which step is next. In this manner, a concept appears in the market as a solution or a difficulty to overcome: the dominant design. The thesis aims to establish an analysis and definition of what a dominant design is and how we should understand this concept: which are the costumers’ demands and needs? How can we relate this information with the dominant design? What is the strategy of the firm before designing a device? Do they use a concept similar to a dominant design?. The research base its analysis in a theoretical framework based in innovation and marketing literature, to then compare the model studied with data collected from surveys made to customers, interviews made to workers of the mobile device market, and different new projects on the market. The research finishes with a discussion about the theoretical and the empirical frameworks, and concludes replying the research questions, and defining a dominant design and its current situation in the market.

  • 156.
    Alizadeh, Mahmoud
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics. KTH, Teknisk informationsvetenskap.
    Characterisation, Modelling and Digital Pre-Distortion Techniques for RF Transmitters in Wireless Systems2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Wireless systems have become an inevitable part of modern technologies serving humankind. The rapid growth towards large dimensional systems, e.g. 5th generation (5G) technologies, incurs needs for improving the performance of the systems and considering aspects to make them as far as possible environmentally friendly in terms of power efficiency, cost, and so on. One of the key parts of every wireless communication system is the radio frequency (RF) power amplifier (PA), which consumes the largest percentage of the total energy. Hence, accurate models of RF PAs can be used to optimize their design and to compensate for signal distortions. This thesis starts with two methods for frequency-domain characterisation to analyse the dynamic behaviour of PAs in 3rd-order non-linear systems. Firstly, two-tone signals superimposed on large-signals are used to analyse the frequency-domain symmetry properties of inter-modulation (IM) distortions and Volterra kernels in different dynamic regions of RF PAs in a single-input single-output (SISO) system. Secondly, three-tone signals are used to characterise the 3rd-order self- and cross-Volterra kernels of RF PAs in a 3 × 3 multiple-input multiple-output (MIMO) system. The main block structures of the models are determined by analysing the frequency-domain symmetry properties of the Volterra kernels in different three-dimensional (3D) frequency spaces. This approach significantly simplifies the structure of the 3rd-order non-linear MIMO model.

    The following parts of the thesis investigate techniques for behavioural modelling and linearising RF PAs. A piece-wise modelling technique is proposed to characterise the dynamic behaviour and to mitigate the impairments of non-linear RF PAs at different operating points (regions). A set of thresholds decompose the input signal into several sub-signals that drive the RF PAs at different operating points. At each operating point, the PAs are modelled by one sub-model, and hence, the complete model consists of several sub-models. The proposed technique reduces the model errors compared to conventional piece-wise modelling techniques.

    A block structure modelling technique is proposed for RF PAs in a MIMO system based on the results of the three-tone characterisation technique. The main structures of the 3rd- and higher-order systems are formulated based on the frequency dependence of each block. Hence, the model can describe more relevant interconnections between the inputs and outputs than conventional polynomial-type models.

    This thesis studies the behavioural modelling and compensation techniques in both the time and the frequency domains for RF PAs in a 3 × 3MIMO system. The 3D time-domain technique is an extension of conventional 2D generalised memory polynomial (GMP) techniques. To reduce the computational complexity, a frequency-domain technique is proposed that is efficient and feasible for systems with long memory effects. In this technique, the parameters of the model are estimated within narrow sub-bands. Each sub-band requires only a few parameters, and hence the size of the model for each sub-band is reduced.

  • 157.
    Alizadeh, Mahmoud
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering. University of Gävle.
    Characterisation, Modelling and Digital Pre-DistortionTechniques for RF Transmitters in Wireless Systems2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Wireless systems have become an inevitable part of modern technologies serving humankind. The rapid growth towards large dimensional systems, e.g. 5th generation (5G) technologies, incurs needs for improving the performance of the systems and considering aspects to make them as far as possible environmentally friendly in terms of power efficiency, cost, and so on. One of the key parts of every wireless communication system is the radio frequency (RF) power amplifier (PA), which consumes the largest percentage of the total energy. Hence, accurate models of RF PAs can be used to optimize their design and to compensate for signal distortions. This thesis starts with two methods for frequency-domain characterisation to analyse the dynamic behaviour of PAs in 3rd-order non-linear systems. Firstly, two-tone signals superimposed on large-signals are used to analyse the frequency-domain symmetry properties of inter-modulation (IM) distortions and Volterra kernels in different dynamic regions of RF PAs in a single-input single-output (SISO) system. Secondly, three-tone signals are used to characterise the 3rd-order self- and cross-Volterra kernels of RF PAs in a 3 × 3 multiple-input multiple-output (MIMO) system. The main block structures of the models are determined by analysing the frequency-domain symmetry properties of the Volterra kernels in different three-dimensional (3D) frequency spaces. This approach significantly simplifies the structure of the 3rd-order non-linear MIMO model.

    The following parts of the thesis investigate techniques for behavioural modelling and linearising RF PAs. A piece-wise modelling technique is proposed to characterise the dynamic behaviour and to mitigate the impairments of non-linear RF PAs at different operating points (regions). A set of thresholds decompose the input signal into several sub-signals that drive the RF PAs at different operating points. At each operating point, the PAs are modelled by one sub-model, and hence, the complete model consists of several sub-models. The proposed technique reduces the model errors compared to conventional piece-wise modelling techniques.

    A block structure modelling technique is proposed for RF PAs in a MIMO system based on the results of the three-tone characterisation technique. The main structures of the 3rd- and higher-order systems are formulated based on the frequency dependence of each block. Hence, the model can describe more relevant interconnections between the inputs and outputs than conventional polynomial-type models.

    This thesis studies the behavioural modelling and compensation techniques in both the time and the frequency domains for RF PAs in a 3 × 3MIMO system. The 3D time-domain technique is an extension of conventional 2D generalised memory polynomial (GMP) techniques. To reduce the computational complexity, a frequency-domain technique is proposed that is efficient and feasible for systems with long memory effects. In this technique, the parameters of the model are estimated within narrow sub-bands. Each sub-band requires only a few parameters, and hence the size of the model for each sub-band is reduced.

  • 158.
    Alizadeh Noghani, Kyoomars
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    SDN Enhanced Ethernet VPN for Data Center Interconnect2017In: 2017 IEEE 6th International Conference on Cloud Networking (CloudNet) / [ed] Maga, D, IEEE, 2017, p. 77-82Conference paper (Refereed)
    Abstract [en]

    Ethernet Virtual Private Network (EVPN) is an emerging technology that addresses the networking challenges presented by geo-distributed Data Centers (DCs). One of the major advantages of EVPN over legacy layer 2 VPN solutions is providing All-Active (A-A) mode of operation so that the traffic can truly be multi-homed on Provider Edge (PE) routers. However, A-A mode of operation introduces new challenges. In the case where the Customer Edge (CE) router is multi-homed to one or more PE routers, it is necessary that only one of the PE routers should forward Broadcast, Unknown unicast, and Multicast (BUM) traffic into the DC. The PE router that assumes the primary role for forwarding BUM traffic to the CE device is called the Designated Forwarder (DF). The proposed solution to select the DF in the EVPN standard is based on a distributed algorithm which has a number of drawbacks such as unfairness and intermittent behavior. In this paper, we introduce a Software-Defined Networking (SDN) based architecture for EVPN support, where the SDN controller interacts with EVPN control plane. We demonstrate how our solution mitigates existing problems for DF selection which leads to improved EVPN performance.

  • 159. Alizai, Muhammad Hamad
    et al.
    Landsiedel, Olaf
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Wehrle, Klaus
    Exploiting the Burstiness of Intermediate-Quality Wireless Links2012In: International Journal of Distributed Sensor Networks, ISSN 1550-1329, p. 826702-Article in journal (Refereed)
    Abstract [en]

    We address the challenge of link estimation and routing over highly dynamic links, thats is, bursty links that rapidly shift between reliable and unreliable periods of transmissions. Based on significant empirical evidence of over 100,000 transmissions over each link in 802.15.4 and 802.11 testbeds, we propose two metrics, expected future transmissions (EFT) and MAC(3), for runtime estimation of bursty wireless links. We introduce a bursty link estimator (BLE) that based on these two metrics, accurately estimates bursty links in the network rendering them available for data transmissions. Finally, we present bursty routing extensions (BRE): an adaptive routing strategy that uses BLE for forwarding packets over bursty links if they offer better routing progress than long-term stable links. Our evaluation, comprising experimental data from widely used IEEE 802.15.4-based testbeds, reveals an average of 19% and a maximum of 42% reduction in the number of transmissions when routing over long-range bursty links typically ignored by routing protocols. Additionally, we show that both BLE and BRE are not tied to any specific routing protocol and integrate seamlessly with existing routing protocols and link estimators.

  • 160.
    Allison, Robert S.
    et al.
    York University, Centre for Vision Research, Toronto, Canada.
    Brunnström, Kjell
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology. RISE AB (Acreo).
    Chandler, Damon M.
    Shizuoka University, Hamamatsu, Shizuoka, Japan.
    Colett, Hannah R.
    Intel Corp., Santa Clara, California, United States.
    Corriveau, Philip J.
    Intel Corp., Santa Clara, California, United States.
    Daly, Scott
    Dolby Laboratories Inc., Sunnyvale, California, United States.
    Goel, James
    Qualcomm Technologies, Inc., Display Video Processing Group, Markham, Canada.
    Long, Juliana Y.
    Intel Corp., Santa Clara, California, United States.
    Wilcox, Laurie M.
    York University, Centre for Vision Research, Toronto, Canada.
    Yaacob, Yusizwan M.
    Shizuoka University, Hamamatsu, Shizuoka, Japan.
    Yang, Shun-nan
    Pacific University, Forest Grove, Oregon, United States.
    Zhang, Yi
    Xi’an Jiaotong University, School of Electronic and Information Engineering, Xi’an, China.
    Perspectives on the definition of visually lossless quality for mobile and large format displays2018In: Journal of Electronic Imaging (JEI), ISSN 1017-9909, E-ISSN 1560-229X, Vol. 27, no 5, p. 1-23, article id 053035Article in journal (Refereed)
    Abstract [en]

    Advances in imaging and display engineering have given rise to new and improved image and videoapplications that aim to maximize visual quality under given resource constraints (e.g., power, bandwidth).Because the human visual system is an imperfect sensor, the images/videos can be represented in a mathematicallylossy fashion but with enough fidelity that the losses are visually imperceptible—commonly termed“visually lossless.” Although a great deal of research has focused on gaining a better understanding ofthe limits of human vision when viewing natural images/video, a universally or even largely accepted definitionof visually lossless remains elusive. Differences in testing methodologies, research objectives, and targetapplications have led to multiple ad-hoc definitions that are often difficult to compare to or otherwise employ inother settings. We present a compendium of technical experiments relating to both vision science and visualquality testing that together explore the research and business perspectives of visually lossless image quality,as well as review recent scientific advances. Together, the studies presented in this paper suggest that a singledefinition of visually lossless quality might not be appropriate; rather, a better goal would be to establish varyinglevels of visually lossless quality that can be quantified in terms of the testing paradigm.

  • 161.
    Allison, R.S.
    et al.
    York University, Canada.
    Brunnstrom, Kjell
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Chandler, D.M.
    Shizuoka University, Japan.
    Colett, H.
    Intel Corp, USA.
    Corriveau, P.
    Intel Corp, USA.
    Daly, S.
    Dolby Laboratories Inc, USA.
    Goel, J.
    Qualcomm Technologies, USA.
    Long, J.Y.
    Intel Corp, USA.
    Wilcox, L.M.
    York University, Canada.
    Yaacob, Y.
    Shizuoka University, Japan.
    Yang, S. N.
    Pacific University, USA.
    Zhang, Y.
    Xi’an Jiaotong University, China.
    Perspectives on the definition of visually lossless quality for mobile and large format displays2018In: Journal of Electronic Imaging, ISSN 10179909, Vol. 27, no 5, article id 053035Article in journal (Refereed)
    Abstract [en]

    Advances in imaging and display engineering have given rise to new and improved image and videoapplications that aim to maximize visual quality under given resource constraints (e.g., power, bandwidth).Because the human visual system is an imperfect sensor, the images/videos can be represented in a mathematicallylossy fashion but with enough fidelity that the losses are visually imperceptible—commonly termed“visually lossless.” Although a great deal of research has focused on gaining a better understanding ofthe limits of human vision when viewing natural images/video, a universally or even largely accepted definitionof visually lossless remains elusive. Differences in testing methodologies, research objectives, and targetapplications have led to multiple ad-hoc definitions that are often difficult to compare to or otherwise employ inother settings. We present a compendium of technical experiments relating to both vision science and visualquality testing that together explore the research and business perspectives of visually lossless image quality,as well as review recent scientific advances. Together, the studies presented in this paper suggest that a singledefinition of visually lossless quality might not be appropriate; rather, a better goal would be to establish varyinglevels of visually lossless quality that can be quantified in terms of the testing paradigm.

  • 162.
    AL-MAMUN, ABDULLAH
    et al.
    Blekinge Institute of Technology, School of Engineering.
    ULLAH, MOHAMMAD RAFIQ
    Blekinge Institute of Technology, School of Engineering.
    Cognitive Radio for Short Range Systems based on Ultra-Wideband2011Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Cognitive Radio (CR) has been proposed as a promising and effective technology to improve radio spectrum utilization. It can change its transmitter parameters depending on the environment in which it operate based on interaction. In CR, a number of different methods of spectrum sensing are used to identify the presence of signal transmission. Among them, the multitaper method (MTM), has been investigated in this thesis paper at the same time with other sensing methods, recently seems to be the best choice for spectrum sensing CR because of its accurate identification and estimation, quick computation, and regularization. This thesis paper is examining how CR can be utilized in short range systems based on Ultra-Wideband (UWB). UWB is a promising technology in wireless communication use for high speed data transmission with low power utilization or long distance localization in both military, radar, sensor, data collection, tracking or commercial application. UWB has the ability to move between very low data rate or very high data rate, short range distance or long range distance applications. Impulse radio UWB (IR-UWB) shows some impressive characteristics in short-range communication systems with varieties of throughput option including high data rates. The strong synergy between the aims of CR and features of IR-UWB has been shown in this thesis. Our key objective is to understand how CR can be applied to UWB systems.

  • 163. Al-Mamun, Abdullah
    et al.
    Ullah, Mohammad Rafiq
    Multitaper spectrum: A promising method in spectrum sensing cognitive radio2010Conference paper (Refereed)
    Abstract [en]

    Cognitive radio (CR) has been proposed as a promising and effective technology to improve radio spectrum utilization. The primary objective of the CR is to handle the non-interference rules with any primary users (PUs). Highly sensitive and optimal spectrum sensing detectors are required in order to avoid harmful interference to PUs. Multitaper spectrum seems to be the most appealing one for spectrum sensing CR because of its accurate identification and estimation and low computational complexity. Mulitaper uses small set of tapers and multiple orthogonal prototype filters to reduce the variance. The Fourier transform of a Slepian sequence, originally known as discrete prolate spheroidal sequences (DPSS), gives maximum energy density inside a given bandwidth and less spectral leakage with better specifications has been investigated in this paper and shows that no other window in signal processing can satisfy this property

  • 164.
    Almquist, Mathias
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Almquist, Viktor
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    A study on Android games: 3G energy consumption, CPU-utilization and system calls2015Independent thesis Basic level (university diploma), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    The popularity of mobile games has increased drastically during the recent years andmany people use them as their main source of entertainment. Mobile gamescommunicate with other devices over the network which consumes a lot of energy,especially when connected to cellular networks (e.g., 3G). This high energy expensecan feel unjustified to the player since always-on network connectivity is not requiredin order to play most games.Furthermore, the number of malware-infected applications in offical applicationstores has increased significantly in the recent years. These malware-infectedapplications can gain unrestricted access and control of users phones which can be athreat to security. Information about the behaviour characteristics of games can beused to develop or improve systems for detecting malware applications.In this thesis, 20 popular Android games are analysed with a focus on the datacommunication, CPU utilization and system call behaviour. The main subject of thedata communication study is the 3G communication energy consumed by games. Thesystem call study aims at quantifying the number and type of calls used by games.This may be useful in a further study of harmful behaviour by apps.The profiling results presented in this report show that the communication energyvaries drastically among games. Games with a very similar gameplay can consumevery different amounts of energy which indicates that there is room for improvementsin many of the games. Ad-free games consume significantly less energy than gamesthat use in-app advertisements. The results show that improving the advertisementfetching policy could reduce the energy consumption of these games. The majority ofthe games can be played without network connectivity and therefore thecommunication energy consumed could be completely avoided. The thesis alsoshows that games use a wide variety of system calls and that many of the system callsare common among the games.

  • 165.
    Almquist, Mathias
    et al.
    Linköping University, Department of Computer and Information Science.
    Almquist, Viktor
    Linköping University, Department of Computer and Information Science.
    Analysis of 360° Video Viewing Behaviours2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis we study users' viewing motions when watching 360° videos in order to provide information that can be used to optimize future view-dependent streaming protocols. More specifically, we develop an application that plays a sequence of 360° videos on an Oculus Rift Head Mounted Display and records the orientation and rotation velocity of the headset during playback. The application is used during an extensive user study in order to collect more than 21 hours of viewing data which is then analysed to expose viewing patterns, useful for optimizing 360° streaming protocols. 

  • 166.
    Almquist, Mathias
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, Faculty of Science & Engineering.
    Almquist, Viktor
    Linköping University, Department of Computer and Information Science. Linköping University, Faculty of Science & Engineering.
    Vergara Alonso, Ekhiotz Jon
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Communication Energy Overhead of Mobiles Games2015In: MobiGames '15: Proceedings of the 2nd Workshop on Mobile Gaming, Association for Computing Machinery (ACM), 2015, p. 1-6Conference paper (Other academic)
    Abstract [en]

    Although a significant proportion of the mobile apps are games there has been little attention paid to their specific characteristics with respect to communication energy. In this paper we select 20 mobile games among the top 100 free Android games, and study their data patterns and communication energy use over a total of 25 hours of playing. The analysis of the energy for communication over 3G networks indicates that there is a wide variation among the games, the largest footprint being 8 times higher than the lowest one. The results also indicates both app-specific and category-specific relations between data pattern and energy use, as well as variations in CPU utilisation.

  • 167.
    Almén, Fredrik
    Linköping University, Department of Science and Technology.
    Band structure computations for dispersive photonic crystals2007Independent thesis Advanced level (degree of Magister), 20 points / 30 hpStudent thesis
    Abstract [en]

    Photonic crystals are periodic structures that offers the possibility to control the propagation of light.

    The revised plane wave method has been implemented in order to compute band structures for photonic crystals. The main advantage of the revised plane wave method is that it can handle lossless dispersive materials. This can not be done with a conventional plane wave method. The computational challenge is comparable to the conventional plane wave method.

    Band structures have been calculated for a square lattice of cylinders with different parameters. Both dispersive and non-dispersive materials have been studied as well as the influence of a surface roughness.

    A small surface roughness does not affect the band structure, whereas larger inhomogeneities affect the higher bands by lowering their frequencies.

  • 168. Al-Qahtani, Fawaz S.
    et al.
    Duong, Quang Trung
    Gurung, Arun K.
    Bao, Vo Nguyen Quoc
    Selection Decode-and-Forward Relay Networks with Rectangular QAM in Nakagami-m Fading Channels2010Conference paper (Refereed)
    Abstract [en]

    In this paper, we investigate the average symbol error probability (SEP) of fixed decode-and-forward relay networks over independent but not identically distributed Nakagami-m fading channels. We have derived closed form expression of SEP for general rectangular quadrature amplitude modulation (QAM) under relay selection scheme where only the best relay forwards message from the source to the destination. The expressions are in terms of hypergeometric series which can be efficiently numerically evaluated. The numerical results are validated with Monte-Carlo simulations.

  • 169. Al-Qahtani, Fawaz S.
    et al.
    Duong, Quang Trung
    Blekinge Institute of Technology, School of Computing.
    Zhong, Caijun
    Qaraqe, Khaild A.
    Alnuweiri, Hussein
    Performance Analysis of Dual-Hop AF Systems with Interference in Nakagami-m Fading Channels2011In: IEEE Signal Processing Letters, ISSN 1070-9908, Vol. 18, no 8, p. 454-457Article in journal (Refereed)
    Abstract [en]

    In this paper, we investigate the performance of dual-hop channel state information-assisted amplify-and-forward relaying systems over Nakagami-m fading channels in the presence of multiple interferers at the relay. Assuming integer fading parameter m, we derive closed-form expressions for the exact outage probability and accurate approximation for symbol error rate of the system. Furthermore, we look into the asymptotical high signal to noise ratio regime, and characterize the diversity order achieved by the system. All the analytical results are validated via Monte Carlo simulations.

  • 170.
    Al-qaissi, Mayss
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    A Study Of Multipath Wave Propagation Using Nero2d and FFT2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this report, the Fast Fourier Transform is described briefly. An implementation, inthe form of the Fortran code four1, is tested to verify the accuracy. A two-ray modelfor wave propagation above a flat earth is discussed. The case with AM modulation isimplemented in a Mathematica script. Calculations of the surface current density, withthe program NERO, are made to test the accuracy. The transient scattering from a PECcylinder is studied by means of the code run_nero that runs NERO repeatedly. From aspectrum calculated in this way, the impulse response is obtained by Fourier inversion.

  • 171.
    Al-Saadeh, Osama
    KTH, School of Information and Communication Technology (ICT).
    Performance of In-Band Full-Duplex for 5G Wireless Networks2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In-band full duplex is a new duplexing scheme that allows radio nodes to transmit and receive, utilizing the same frequency and time resources. The implementation of in-band full duplex was not feasible in practice, due to the effect of self-interference. But then, advances in signal processing made it possible to reduce this effect. However, the system level performance of in-band full duplex has not been investigated thoroughly.Through computer simulations, we investigate the performance of in-band full duplex, for indoor 5G small cell wireless networks. We examine the performance of in-band full duplex in comparison to dynamic and static time division duplexing. Additionally, we analyze the performance of the duplexing schemes with two interference mitigation techniques, namely beamforming and interference cancellation.Our results indicate that for highly utilized wireless networks, in-band full duplex should be combined with beamforming and interference cancellation, in order to achieve a performance gain over traditional duplexing schemes. Only then, in-band full duplex is considered advantageous, at any network utilization, and any downlink to uplink traffic demand proportion. Our results also suggest that in order to achieve a performance gain with in-band full duplex in both links, the transmit power of the access points should be comparable to the transmit power of the mobile stations.

  • 172. Al-Saadeh, Osama
    et al.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    A performance comparison of in-band full duplex and dynamic TDD for 5G indoor wireless networks2017In: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, article id 50Article in journal (Refereed)
    Abstract [en]

    In-band full duplex has emerged as a solution for high data rate and low access delay for 5G wireless networks after its feasibility has been demonstrated. However, the impact of the in-band full duplex on the system-level performance of multi-cell wireless networks has not been investigated thoroughly. In this paper, we conduct an extensive simulation study to investigate the performance of in-band full duplex for indoor 5G small cell wireless networks. Particularly, we compare the in-band full duplex with static and dynamic time division duplexing schemes which require much less hardware complexity. We examine the effects of beamforming and interference cancellation under various traffic demands and asymmetry situations in the performance comparison. Our objective is to identify under which condition and with which technology support the in-band full duplex becomes advantageous over the simpler duplexing schemes. Numerical results indicate that for highly utilized wireless networks, in-band full duplex should be combined with interference cancellation and beamforming in order to achieve a performance gain over traditional duplexing schemes. Only then in-band full duplex is considered to be advantageous at any number of active mobile stations in the network and any downlink to uplink traffic proportion. Our results also suggest that in order to achieve a performance gain with the in-band full duplex in both links, the transmit power of the access points and the mobile stations should be comparable.

  • 173.
    Al-Tahir, Hibah
    University of Gävle, Department of Technology and Built Environment.
    Multidimensional Measurements: on RF Power Amplifiers2008Independent thesis Advanced level (degree of Magister), 20 points / 30 hpStudent thesis
    Abstract [en]

    Abstract

    In this thesis, a measurement system was set to perform comprehensive measurements on RF power amplifiers. Data obtained from the measurements is then processed mathematically to obtain three dimensional graphs of the basic parameters affected or generated by nonlinearities of the amplifier i.e. gain, efficiency and distortion. Using a class AB amplifier as the DUT, two sets of signals – both swept in power level and frequency - were generated to validate the method, a two-tone signal and a WCDMA signal. The three dimensional plot gives a thorough representation of the behavior of the amplifier in any arbitrary range of spectrum and input level. Sweet spots are consequently easy to detect and analyze. The measurement setup can also yield other three dimensional plots of variations of gain, efficiency or distortion versus frequencies and input levels. Moreover, the measurement tool can be used to plot traditional two dimensional plots such as, input versus gain, frequency versus efficiency etc, making the setup a practical tool for RF amplifiers designers.

    The test signals were generated by computer then sent to a vector signal generator that generates the actual signals fed to the amplifier. The output of the amplifier is fed to a vector signal analyzer then collected by computer to be handled. MATLAB® was used throughout the entire process.

    The distortion considered in the case of the two-tone signals is the third order intermodulation distortion (IM3) whereas Adjacent Channel Power Ratio (ACPR) was considered in the case of WCDMA.

  • 174.
    Aluguri, Tarun
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Performance Evaluation of OpenStack Deployment Tools2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Cloud computing enables on-demand access to a shared pool of computing resources, that can beeasily provisioned, configured and released with minimal management cost and effort. OpenStack isan open source cloud management platform aimed at providing private or public IaaS cloud onstandard hardware. Since, deploying OpenStack manually is tedious and time-consuming, there are several tools that automate the deployment of OpenStack. Usually, cloud admins choose a tool basedon its level of automation, ease of use or interoperability with existing tools used by them. However,another desired factor while choosing a deployment tool is its deployment speed. Cloud admins cannot select based on this factor since, there is no previous work on the comparison of deploymenttools based on deployment time. This thesis aims to address this issue.

    The main aim of the thesis is to evaluate the performance of OpenStack deployment tools with respectto operating system provisioning and OpenStack deployment time, on physical servers. Furthermore,the effect of varying number of nodes, OpenStack architecture deployed and resources (cores andRAM) provided to deployment node on provisioning and deployment times, is also analyzed. Also,the tools classified based on stages of deployment and method of deploying OpenStack services. In this thesis we evaluate the performance of MAAS, Foreman, Mirantis Fuel and Canonical Autopilot.

    The performance of the tools is measured via experimental research method. Operating system provisioning time and OpenStack deployment times are measured while varying the number of nodes/OpenStack architecture and resources provided to deployment node i.e. cores and RAM.

    Results show that provisioning time of MAAS is less than Mirantis Fuel, which is less than Foreman.Furthermore, for all 3 tools as number of nodes increases provisioning time increases. However, the amount of increase is lowest for MAAS than Mirantis Fuel and Foreman. Similarly, results for baremetal OpenStack deployment time show that, Canonical Autopilot outperforms Mirantis Fuel by asignificant difference for all OpenStack scenarios considered. Furthermore, as number of nodes in an OpenStack scenario increases, the deployment time for both the tools increases.

    From the research, it is concluded that MAAS and Canonical Autopilot perform better as provisioningand bare metal OpenStack deployment tool respectively, than other tools that have been analyzed.Furthermore, from the analysis it can be concluded that increase in number of nodes/ OpenStackarchitecture, leads to an increase in both provisioning time and OpenStack deployment time for all the tools.

  • 175.
    Al-Zubaidy, Hussein
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Fodor, Viktoria
    KTH, School of Electrical Engineering (EES), Network and Systems engineering. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Dán, György
    KTH, School of Electrical Engineering (EES), Network and Systems engineering. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Flierl, Markus
    KTH, School of Electrical Engineering (EES), Information Science and Engineering. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Reliable Video Streaming With Strict Playout Deadline in Multihop Wireless Networks2017In: IEEE transactions on multimedia, ISSN 1520-9210, E-ISSN 1941-0077, Vol. 19, no 10, p. 2238-2251Article in journal (Refereed)
    Abstract [en]

    Motivated by emerging vision-based intelligent services, we consider the problem of rate adaptation for high-quality and low-delay visual information delivery over wireless networks using scalable video coding. Rate adaptation in this setting is inherently challenging due to the interplay between the variability of the wireless channels, the queuing at the network nodes, and the frame-based decoding and playback of the video content at the receiver at very short time scales. To address the problem, we propose a low-complexity model-based rate adaptation algorithm for scalable video streaming systems, building on a novel performance model based on stochastic network calculus. We validate the analytic model using extensive simulations. We show that it allows fast near-optimal rate adaptation for fixed transmission paths, as well as cross-layer optimized routing and video rate adaptation in mesh networks, with less than 10% quality degradation compared to the best achievable performance.

  • 176.
    Amadeo, Marica
    et al.
    Dipartimento DIIES, Università Mediterranea di Reggio Calabria, Reggio Calabria, Italy.
    Campolo, Claudia
    Dipartimento DIIES, Università Mediterranea di Reggio Calabria, Reggio Calabria, Italy.
    Molinaro, Antonella
    Dipartimento DIIES, Università Mediterranea di Reggio Calabria, Reggio Calabria, Italy & Laboratoire des Signaux et Systémes (L2S), CentraleSupélec-CNRS-Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France.
    Harri, Jerome
    Department of Communication Systems, EURECOM, Sophia Antipolis, France.
    Rothenberg, Christian Esteve
    School of Electrical and Computer Engineering, University of Campinas (UNICAMP), Campinas, Brazil.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Enhancing the 3GPP V2X Architecture with Information-Centric Networking2019In: Future Internet, ISSN 1999-5903, E-ISSN 1999-5903, Vol. 11, no 9, article id 199Article in journal (Refereed)
    Abstract [en]

    Vehicle-to-everything (V2X) communications allow a vehicle to interact with other vehicles and with communication parties in its vicinity (e.g., road-side units, pedestrian users, etc.) with the primary goal of making the driving and traveling experience safer, smarter and more comfortable. A wide set of V2X-tailored specifications have been identified by the Third Generation Partnership Project (3GPP) with focus on the design of architecture enhancements and a flexible air interface to ensure ultra-low latency, highly reliable and high-throughput connectivity as the ultimate aim. This paper discusses the potential of leveraging Information-Centric Networking (ICN) principles in the 3GPP architecture for V2X communications. We consider Named Data Networking (NDN) as reference ICN architecture and elaborate on the specific design aspects, required changes and enhancements in the 3GPP V2X architecture to enable NDN-based data exchange as an alternative/complementary solution to traditional IP networking, which barely matches the dynamics of vehicular environments. Results are provided to showcase the performance improvements of the NDN-based proposal in disseminating content requests over the cellular network against a traditional networking solution. © 2019 by the authors.

  • 177.
    Amarasuriya, Gayan
    et al.
    Princeton University, NJ 08544 USA.
    Larsson, Erik G
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Vincent Poor, H.
    Princeton University, NJ 08544 USA.
    Wireless Information and Power Transfer in Multiway Massive MIMO Relay Networks2016In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 15, no 6, p. 3837-3855Article in journal (Refereed)
    Abstract [en]

    Simultaneous wireless information and power transfer techniques for multiway massive multiple-input multiple-output (MIMO) relay networks are investigated. By using two practically viable relay receiver designs, namely 1) the power splitting receiver and 2) the time switching receiver, asymptotic signal-to-interference-plus-noise ratio (SINR) expressions are derived for an unlimited number of antennas at the relay. These asymptotic SINRs are then used to derive asymptotic symmetric sum rate expressions in closed form. Notably, these asymptotic SINRs and sum rates become independent of radio frequency-to-direct current (RF-to-DC) conversion efficiency in the limit of infinitely many relay antennas. Moreover, tight average sum rate approximations are derived in closed form for finitely many relay antennas. The fundamental tradeoff between the harvested energy and the sum rate is quantified for both relay receiver structures. Notably, the detrimental impact of imperfect channel state information (CSI) on the MIMO detector/precoder is investigated, and thereby, the performance degradation caused by pilot contamination, which is the residual interference due to nonorthogonal pilot sequence usage in adjacent/cochannel systems, is quantified. The presence of cochannel interference (CCI) can be exploited to be beneficial for energy harvesting at the relay, and consequently, the asymptotic harvested energy is an increasing function of the number of cochannel interferers. Notably, in the genie-aided perfect CSI case, the detrimental impact of CCI for signal decoding can be cancelled completely whenever the number of relay antennas grows without bound. Nevertheless, the pilot contamination severely degrades the sum rate performance even for infinitely many relay antennas.

  • 178.
    Amin, Shoaib
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    Zenteno, Efrain
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    Landin, Per
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    Rönnow, Daniel
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    Isaksson, Magnus
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    Händel, Peter
    ACCESS Linnaeus Centre, Signal Processing Lab, KTH Royal Institute of Technology.
    Noise Impact on the Identification of DigitalPredistorter Parameters in the Indirect LearningArchitecture2012In: 2012 Swedish Communication Technologies Workshop (Swe-CTW), IEEE conference proceedings, 2012, p. 36-39Conference paper (Refereed)
    Abstract [en]

    The indirect learning architecture (ILA) is the mostused methodology for the identification of Digital Pre-distorter(DPD) functions for nonlinear systems, particularly for highpower amplifiers. The ILA principle works in black box modelingrelying on the inversion of input and output signals of thenonlinear system, such that the inverse is estimated. This paperpresents the impact of disturbances, such as noise in the DPDidentification. Experiments were performed with a state-of-artDoherty power amplifier intended for base station operationin current telecommunication wireless networks. As expected,a degradation in the performance of the DPD (measured innormalized mean square error (NMSE)) is found in our experiments.However, adjacent channel power ratio (ACPR) canbe a misleading figure of merit showing improvement in theperformance for wrongly estimated DPD functions.

  • 179.
    Amin, Yasar
    et al.
    KTH, School of Information and Communication Technology (ICT), Electronic, Computer and Software Systems, ECS.
    Tenhunen, Hannu A.
    KTH, School of Information and Communication Technology (ICT), Electronic, Computer and Software Systems, ECS.
    Zheng, Lirong
    KTH, School of Information and Communication Technology (ICT), Electronic, Computer and Software Systems, ECS.
    Blueprint and integration of vastly efficient 802.11A WLAN front-end2006In: WSEAS Transactions on Electronics, ISSN 1109-9445, Vol. 3, no 4, p. 258-261Article in journal (Refereed)
    Abstract [en]

    Next generation wireless communications terminals will demand the use of advanced component integration processes and high density packaging technologies in order to reduce size and to increase performance. This paper presents high density multilayer interconnects and integrated passives used to design high performance prototype filter for 5GHz wireless LAN receiver realized on MCM-D substrate. The thin film implementation of Multichip Module technology is identified as a useful platform for the integration of GaAs MMIC and silicon device technologies for microwave applications where performance, size and weight are critical factors. The ability of the MCM-D technology to provide controlled impedance, microstrip structures and integrated thin film passive components with useful performance in the microwave frequency regime has now been demonstrated.

  • 180.
    Amin, Yasar
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Tenhunen, Hannu
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Jamal, Habibullah
    Zheng, Li-Rong
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Duo, Xinzhong
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Chip-package codesign of receiver front end modules for RF/wireless applications2005In: 2005 IEEE/ACES International Conference on Wireless Communications and Applied Computational Electromagnetics, New York: IEEE , 2005, p. 767-770Conference paper (Refereed)
  • 181.
    Amjad, Shoaib
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Malhi, Rohail Khan
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Burhan, Muhammad
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    DIFFERENTIAL CODE SHIFTED REFERENCE IMPULSE-BASED COOPERATIVE UWB COMMUNICATION SYSTEM2013Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Cooperative Impulse Response – Ultra Wideband (IR-UWB) communication is a radio technology very popular for short range communication systems as it enables single-antenna mobiles in a multi-user environment to share their antennas by creating virtual MIMO to achieve transmit diversity. In order to improve the cooperative IR-UWB system performance, we are going to use Differential Code Shifted Reference (DCSR). The simulations are used to compute Bit Error Rate (BER) of DCSR in cooperative IR-UWB system using different numbers of Decode and Forward relays while changing the distance between the source node and destination nodes. The results suggest that when compared to Code Shifted Reference (CSR) cooperative IR-UWB communication system; the DCSR cooperative IR-UWB communication system performs better in terms of BER, power efficiency and channel capacity. The simulations are performed for both non-line of sight (N-LOS) and line of sight (LOS) conditions and the results confirm that system has better performance under LOS channel environment. The simulation results also show that performance improves as we increase the number of relay nodes to a sufficiently large number.

  • 182.
    AMUJALA, NARAYANA KAILASH
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    SANKI, JOHN KENNEDY
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Video Quality of Experience through Emulated Mobile Channels2014Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Over the past few years, Internet traffic took a ramp increase. Of which, most of the traffic is video traffic. With the latest Cisco forecast it is estimated that, by 2017 online video will be highly adopted service with large customer base. As the networks are being increasingly ubiquitous, applications are turning equally intelligent. A typical video communication chain involves transmission of encoded raw video frames with subsequent decoding at the receiver side. One such intelligent codec that is gaining large research attention is H.264/SVC, which can adapt dynamically to the end device configurations and network conditions. With such a bandwidth hungry, video communications running over lossy mobile networks, its extremely important to quantify the end user acceptability. This work primarily investigates the problems at player user interface level compared to the physical layer disturbances. We have chosen Inter frame time at the Application layer level to quantify the user experience (player UI) for varying lower layer metrics like noise and link power with nice demonstrator telling cases. The results show that extreme noise and low link level settings have adverse effect on user experience in temporal dimension. The video are effected with frequent jumps and freezes.

  • 183.
    Anani, Adi
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    M-learning in review: Technology, standard and evaluation2008In: Journal of Communication and Computer, ISSN 1548-7709, Vol. 5, no 11, p. 1-6Article in journal (Refereed)
    Abstract [en]

    Nowadays E-learning as a form of learning depending on networks and computer devices has been expanding by leaps and bounds. As a special kind of E-learning, M-learning (mobile learning) aims at the use of mobile devices anywhere at anytime by anybody. In this paper, the technologies to develop a M-learning system is deeply analyzed according to the layer model at first. Secondly, from the view of application, the standardization in M-learning is researched in order to accelerate the development and popularization of M-learning. Finally, quality estimation of M-learning system is discussed from the view of QoE (quality of experiences). The experience form end-user is the sole effective norm to judge the result of M-learning technology. It is no doubt that technologies, standardization and evaluation will play very important parts in the course of M-learning development.

  • 184.
    Anani, Adi
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Zhang, Deng-yin
    Institute of Signal Processing and Transmission, Nanjing University of Posts and Telecommunications, China.
    Li, Haibo
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    QoS-guaranteed packet scheduling in wireless networks2009In: Journal of China Universities of Posts and Telecommunications, ISSN 1005-8885, Vol. 16, no 2, p. 63-67Article in journal (Refereed)
    Abstract [en]

    To guarantee the quality of service (QoS) of a wireless network, a new packet scheduling algorithm using cross-layer design technique is proposed in this article. First, the demand of packet scheduling for multimedia transmission in wireless networks and the deficiency of the existing packet scheduling algorithms are analyzed. Then the model of the QoS-guaranteed packet scheduling (QPS) algorithm of high speed downlink packet access (HSDPA) and the cost function of packet transmission are designed. The calculation method of packet delay time for wireless channels is expounded in detail, and complete steps to realize the QPS algorithm are also given. The simulation results show that the QPS algorithm that provides the scheduling sequence of packets with calculated values can effectively improve the performance of delay and throughput.

  • 185.
    ananth, Indirajith Vijai
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Study on Assessing QoE of 3DTV Using Subjective Methods2013Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    The ever increasing popularity and enormous growth in 3D movie industry is the stimulating phenomenon for the penetration of 3D services into home entertainment systems. Providing a third dimension gives intense visual experience to the viewers. Being a new eld, there are several researches going on to measure the end user's viewing experience. Research groups including 3D TV manufacturers, service providers and standards organizations are interested to improve user experience. Recent research in 3D video quality measurements have revealed uncertain issues as well as more well known results. Measuring the perceptual stereoscopic video quality by subjective testing can provide practical results. This thesis studies and investigate three di erent rating scales (Video Quality, Visual Discomfort and Sense of Presence) and compares them by subjective testing, combined with two viewing distances at 3H and 5H, where H is the hight of display screen. This thesis work shows that single rating scale produces the same result as three di erent scales and viewing distance has very less or no impact on Quality of Experience (QoE) of 3DTV for 3H and 5H distances for symmetric coding impairments.

  • 186.
    Anchora, Luca
    et al.
    IMT of Lucca.
    Badia, Leonardo
    Università degli Studi di Padova.
    Karipidis, Eleftherios
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    Zorzi, Mikele
    Università degli Studi di Padova.
    Capacity Gains due to Orthogonal Spectrum Sharing in Multi-Operator LTE Cellular Networks2012In: Proceedings of the Ninth International Symposium on Wireless Communication Systems (ISWCS), 2012, p. 286-290Conference paper (Refereed)
    Abstract [en]

    Static spectrum allocation leads to resource wastage and inter-operator spectrum sharing is a possible way to improve spectrum efficiency. In this work, we assume that two cellular network operators agree upon sharing part of their spectrum, which can then be dynamically accessed by either of them in a mutually exclusive way. Our goal is to numerically assess the gain, in terms of cell capacity, due to such orthogonal spectrum sharing. Hence, we propose a centralized algorithm that performs coordinated scheduling, in order to numerically evaluate an upper bound on the achievable sum capacity. The algorithm is centralized and exploits complete information on both networks to perform the optimum allocation. The simulation results illustrate the impact of the multiuser diversity and the asymmetry in the traffic load among the networks on the overall achievable gain.

  • 187.
    Anchora, Luca
    et al.
    IMT of Lucca.
    Badia, Leonardo
    Università degli Studi di Padova.
    Zhang, Haibin
    TNO ICT.
    Fahldieck, Torsten
    Bell Labs, Alcatel-Lucent.
    Zhang, Jianshu
    Ilmenau University of Technology.
    Szydelko, Michal
    Wroclaw Research Centre EIT+ .
    Schubert, Martin
    Fraunhofer Institute for Telecommunications HHI.
    Karipidis, Eleftherios
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    Haardt, Martin
    Ilmenau University of Technology.
    Resource Allocation and Management in Multi-Operator Cellular Networks with Shared Physical Resources2012In: Proceedings of the Ninth International Symposium on Wireless Communication Systems (ISWCS), IEEE , 2012, p. 296-300Conference paper (Refereed)
    Abstract [en]

    In this paper, we focus on next-generation cellular networks and discuss physical resources sharing among the operators. This implies cooperative usage of the available radio frequencies and also infrastructure sharing. In particular, we analyze the spectrum sharing gain achievable at different time scales and the main factors impacting on it. Then, we move towards a wider idea of resource sharing and consider a joint spectrum and infrastructure sharing (full sharing). We describe a two-layer resource management architecture that enables operators to reduce costs while still guaranteeing a good service level. The main findings of our investigations are to quantify the effectiveness of resource sharing and open up new perspectives for the operators of next-generation networks.

  • 188.
    Ande, Rama kanth
    et al.
    Blekinge Institute of Technology, School of Computing.
    Amarawadi, Sharath Chandra
    Blekinge Institute of Technology, School of Computing.
    Evaluation of ROS and Arduino Controllers for the OBDH Subsystem of a CubeSat2012Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    CubeSat projects in various universities around the world have become predominant in the study and research for developing CubeSats. Such projects have broadened the scope for understanding this new area of space research. Different CubeSats have been developed by other universities and institutions for different applications. The process of design, development and deployment of CubeSats involves several stages of theoretical and practical work ranging from understanding the concepts associated with communication subsystems, data handling subsystems to innovations in the field like implementing compatible operating systems in the CubeSat processors and new designs of transceivers and other components. One of the future trend setting research areas in CubeSat projects is the implementation of ROS in CubeSat. Robot Operating System (ROS) is aiming to capture the future of many embedded systems including Robotics. In this thesis, an attempt is made to understand the challenges faced during implementing ROS in CubeSat to provide a foundation for the OBDH subsystem and provide important guidelines for future developers relying on ROS run CubeSats. Since using traditional transceivers and power supply would be expensive, we have tried simulating Arduino to act as transceiver and power supply subsystems. Arduino is an open-source physical computing platform based on a simple microcontroller board, and a development environment for writing software for the board designed to make the process of using electronics in major embedded projects more accessible and inexpensive. Another important focus in this thesis has been to establish communication between CubeSat kit and Arduino. The major motivating factor for this thesis was to experiment with and come up with alternate ways which could prove as important measures in future to develop an effective and useful CubeSat by cutting down on development costs. An extensive literature review is carried out on the concepts of Arduino boards and ROS and its uses in Robotics which served as a base to understand its use in CubeSat. Experiment is conducted to communicate the CubeSat kit with Arduino. The results from the study of ROS and experiments with Arduino have been highly useful in drafting major problems and complications that developers would encounter while implementing ROS in CubeSat. Comprehensive analysis to the results obtained serve as important suggestions and guidelines for future researchers working in this field.

  • 189.
    Andersson, Eskil
    et al.
    Blekinge Institute of Technology, Department of Human Work Science and Media Technology.
    Akrawi, Sirvan
    Blekinge Institute of Technology, Department of Human Work Science and Media Technology.
    CU2: Design av ett PDA-baserat diskussionverktyg med ljud/bildkommunikation2001Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [sv]

    I detta arbete framlägger vi ett designförslag på hur ett diskussionsverktyg som stödjer ljud- och bildkommunikation kan se ut. Ett förslag som förbättrar och förenklar den distanskommunikation som idag sker med hjälp av mobiltelefoner, videokonferenssystem samt webbkameror anslutna till persondatorer. Den design vi föreslår möjliggör för mobila användare att visuellt föra flerpartssamtal med hjälp av PDA:er. Vårt designförslag har fått arbetsnamnet CU2 (see you too) och är tänkt att fungera i tredje och/eller fjärde generationens mobila nät. Vi har valt att genomföra vårt magisterarbete på företaget A Brand New World i Kista, Stockholm. Företaget utvecklar och säljer system inom mobilt Internet.

  • 190.
    Andersson, Fredrik
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Grafisk utvecklingsplattform för signalbehandling - Design och implementation2013Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    We have different kinds of signal processing everywhere around us in our everyday life, in our cellphones, when we are listening to music, watching TV etc. This makes signal processing a very interesting and important technical area, where the demand of skilled engineers sets the limit of what is possible.

    Working with signal processing requires in-depth knowledge in areas such as mathematics, physics, electronics, and other related areas. For this, it has traditionally been demanded by a talented developer to also master the advanced programming languages such as C / C + + and Assembler.

    This has begun to change; today there are several companies that offer graphical development environments for signal processing, environments where programming skills are not needed anymore, and the focus can be on signal processing instead.

    The goal with this project is to build a corresponding graphical development environment to reach an understanding of what is required of these systems, and also to grasp what opportunities that are available within graphic programming. Inspiration for the work has partly arise from some of the tools available on the market, and partly from previous theses that have been written about graphic programming.

    The challenge lies in creating a program that can execute signal diagrams in real time from given signal blocks, and be able to handle feedback loops in an efficient way and to do so at the lowest "cost" in terms of clock cycles as possible. This should also be compared against to code, compile and run a complete signal diagram directly.

    To increase the usability it should also be possibility to externally manage in real time the parameters of the signal diagram during execution.

    The interface is a separate program, which is to some extent similar to Matlab Simulink, where a signal diagram is drawn up graphically by connecting wires between different signal blocks. This signal scheme is then executed in an additional program that serves as a runtime environment. In this report, the term "signal engine" is used for this program.

    Signal engine is equivalent to the program that should have been run directly into a standalone DSP (Digital Signal Processor) if a more classic design had been selected, but now runs as a separate process in Windows.

  • 191.
    Andersson, Fredrik
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Utveckling av GIS-applikation för effektivisering av planeringsarbeten för infrastruktur2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Planeringsarbeten för infrastruktur sker ofta med hjälp av speciella programvaror som CAD för att skapa ritningar på kartor över områden där tänkta infrastrukturer skall utvecklas. Som en effektivisering för dessa arbeten handlar denna studie om implementering av en GIS-applikation för att motivera fördelar med GIS och sättet för hantering samt visualisering av geografisk information. En webbapplikation som hanterar baskartor samt överliggande vektorlager för infrastruktur utvecklas, samt även att samma kartdata över infrastrukturen kopplas till en mobilapplikation för att effektivisera eventuella inventeringsarbeten av infrastrukur med hjälp av GPS för att kunna positionera infrastruktur på ett bra sätt. Tekniken bakom utvecklingen bygger på HTML, CSS och JavaScript samt molntjänstlagrin av infrastruktursdata i en geodatabas . GIS-applikationen sammanställer svar på frågor som bevisar hur GIS på ett tillfredställande sätt mycket väl skulle kunna implementeras och användas praktiskt i ett utvecklingsarbete för infrastruktur i dagens morderna samhälle. 

  • 192.
    Andersson, Göran
    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.
    Västberg, Anders
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth. KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Devlic, Alisa
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth. KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Energy efficient heterogeneous network deployment with cell DTX2016In: 2016 IEEE International Conference on Communications (ICC),, IEEE, 2016, p. 1-6Conference paper (Refereed)
    Abstract [en]

    This paper evaluates different means of reducing power consumption of macro base stations (BS) and heterogeneous mobile network deployments (HetNet) considering the time dimension. These approaches are based on the same idea of reducing the load of heavily loaded macro cells and putting them to discontinuous transmission (DTX) mode during the time of inactivity by either (1) macro cell densification or (2) offloading traffic to small cells. Activity factor of a BS is defined as the fraction of time the BS is transmitting over a fixed time period. It is shown that by macro cell layer network densification, the average daily area power consumption can be reduced by up to 73 % with the use of cell DTX. However, reducing the activity factor by macro layer densification is not cost effective, as already demonstrated in previous studies. Alternatively, by adding small cells and enabling their DTX capability, power consumption can be reduced by up to 29 %. Adding small cells is especially effective in terms of energy savings, when users are distributed around hot spots, where additional coverage and capacity is required.

  • 193.
    Andersson, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Parallel Simulation: Parallel computing for high performance LTE radio network simulations2010Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Radio access technologies for cellular mobile networks are continuously being evolved to meet the future demands for higher data rates, and lower end‐to‐end delays. In the research and development of LTE, radio network simulations play an essential role. The evolution of parallel processing hardware makes it desirable to exploit the potential gains of parallelizing LTE radio network simulations using multithreading techniques in contrast to distributing experiments over processors as independent simulation job processes. There is a hypothesis that parallel speedup gain diminishes when running many parallel simulation jobs concurrently on the same machine due to the increased memory requirements. A proposed multithreaded prototype of the Ericsson LTE simulator has been constructed, encapsulating scheduling, execution and synchronization of asynchronous physical layer computations. In order to provide implementation transparency, an algorithm has been proposed to sort and synchronize log events enabling a sequential logging model on top of non‐deterministic execution. In order to evaluate and compare multithreading techniques to parallel simulation job distribution, a large number of experiments have been carried out for four very diverse simulation scenarios. The evaluation of the results from these experiments involved analysis of average measured execution times and comparison with ideal estimates derived from Amdahl’s law in order to analyze overhead. It has been shown that the proposed multithreaded task‐oriented framework provides a convenient way to execute LTE physical layer models asynchronously on multi‐core processors, still providing deterministic results that are equivalent to the results of a sequential simulator. However, it has been indicated that distributing parallel independent jobs over processors is currently more efficient than multithreading techniques, even though the achieved speedup is far from ideal. This conclusion is based on the observation that the overhead caused by increased memory requirements, memory access and system bus congestion is currently smaller than the thread management and synchronization overhead of the proposed multithreaded Java prototype.

  • 194.
    Andersson, Mattias
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Coding and Transmission Strategies for Secrecy2014Doctoral thesis, monograph (Other academic)
    Abstract [en]

    In this thesis we consider several problems relating to information theoretic security. The wiretap channel is the simplest information theoretic setting which takes security into account, and in the first chapters of the thesis we design some practical coding schemes for this channel model.

    First we consider the design of two edge type low density parity check (LDPC) codes for the binary erasure wiretap channel (BEC-WT). For the scenario when the main channel is error free and the wiretapper's channel is a binary erasure channel (BEC) we find secrecy capacity achieving code sequences based on standard LDPC code sequences for the BEC. However, this construction does not work when there are also erasures on the main channel. For this case we develop a method based on linear programming to optimize two edge type degree distributions. Using this method we find code ensembles that perform close to the secrecy capacity of the BEC-WT. We generalize a method of Méasson, Montanari, and Urbanke in order to compute the conditional entropy of the message at the wiretapper. We apply this method to relatively simple ensembles and find very good secrecy performance.

    We then show that Arikan's polar codes can be used to achieve the whole capacity-equivocation region of for any degraded symmetric binary input wiretap channel. We also design capacity achieving polar codes for the decode-and-forward scheme for the physically degraded relay channel, and for the bidirectional broadcast channel with common and confidential messages.

    In the subsequent chapter we consider a Gaussian system model. We show that sparse regression codes (SPARCS) as introduced by Joseph and Barron achieve the secrecy capacity of the additive white Gaussian noise (AWGN) wiretap channel, and can be used to implement the decode-and-forward scheme for the Gaussian relay channel. We also consider secret key agreement using correlated Gaussian random variables and a rate-limited public channel. We show that SPARCs attain the capacity region also for this problem.

    Finally we consider secret key agreement over reciprocal fading channels. We first consider a multiple-antenna setup in the high signal-to-noise-ratio (SNR) regime and propose a scheme based on training and randomness sharing. We then consider a single antenna setup in the low SNR regime, where one of the terminals is only allowed to transmit pilot signals. We propose a bursty transmission scheme based on training and opportunistic transmission using a wiretap channel code, and show that this scheme is optimal.

  • 195.
    Andersson, Mattias
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Coding for the Wiretap Channel2011Licentiate thesis, monograph (Other academic)
    Abstract [en]

    We consider code design for Wyner’s wiretap channel. Optimal coding schemes for this channel require an overall code that is capacity achieving for the main channel, partitioned into smaller subcodes, all of which are capacity achieving for the wiretapper’s channel. To accomplish this we introduce two edge type low density parity check (LDPC) ensembles for the wiretap channel. For the scenario when the main channel is error free and the wiretapper’s channel is a binary erasure channel (BEC) we find secrecy capacity achieving code sequences based on standard LDPC code sequences for the BEC. However, this construction does not work when there are also erasures on the main channel. For this case we develop a method based on linear programming to optimize two edge type degree distributions. Using this method we find code ensembles that perform close to the secrecy capacity of the binary erasure wiretap channel (BEC- WT). We generalize a method of M ́easson, Montanari, and Urbanke in order to compute the conditional entropy of the message at the wire- tapper. This conditional entropy is a measure of how much information is leaked to the wiretapper. We apply this method to relatively simple ensembles and find that they show very good secrecy performance.

    Based on the work of Kudekar, Richardson, and Urbanke, which showed that regular spatially coupled codes are capacity achieving for the BEC, we construct a regular two edge type spatially coupled ensem- ble. We show that this ensemble achieves the whole capacity-equivocation region for the BEC-WT.

    We also find a coding scheme using Arıkans polar codes. These codes achieve the whole capacity-equivocation region for any symmetric binary input wiretap channel where the wiretapper’s channel is degraded with respect to the main channel.

     

  • 196.
    Andersson, Mattias
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Khisti, Ashish
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Secret-key agreement over a non-coherent block-fading MIMO wiretap channel2012In: Information Theory Workshop (ITW), 2012 IEEE, IEEE , 2012, p. 153-157Conference paper (Refereed)
    Abstract [en]

    We study secret-key agreement over a non-coherent block-fading multiple input multiple output (MIMO) wiretap channel. We give an achievable scheme based on training and source emulation and analyze the rate in the high SNR regime. Based on this analysis we find the optimal number of antennas to use for training. Our main result is that if the sum of the number of antennas at Alice and Bob is larger than the coherence time of the channel, the achievable rate does not depend on the number of antennas at Eve. In this case source emulation is not needed, and using only training is optimal. We also consider the case when there is no public channel available. In this case we show that secret-key agreement is still possible by using the wireless channel for discussion, giving the same number of secure degrees of freedom as in the case with a public channel.

  • 197.
    Andersson, Mattias
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Rathi, Vishwambhar
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Kliewer, Joerg
    Klipsch School of Electrical and Computer Engineering New Mexico State University.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Equivocation of Eve using two edge type LDPC codes for the binary erasure wiretap channel2010In: 2010 Conference Record of the Forty Fourth Asilomar Conference on Signals, Systems and Computers (ASILOMAR), 2010, p. 2045-2049Conference paper (Refereed)
    Abstract [en]

    We consider transmission over a binary erasure wiretap channel using the code construction method introduced by Rathi et al. based on two edge type Low-Density Parity-Check (LDPC) codes and the coset encoding scheme. By generalizing the method of computing conditional entropy for standard LDPC ensembles introduced by Méasson, Montanari, and Urbanke to two edge type LDPC ensembles, we show how the equivocation for the wiretapper can be computed. We find that relatively simple constructions give very good secrecy performance and are close to the secrecy capacity.

  • 198.
    Andersson, Mattias
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Communication Theory.
    Rathi, Vishwambhar
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Kliewer, Jorg
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Communication Theory.
    Nested Polar Codes for Wiretap and Relay Channels2010In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 14, no 8, p. 752-754Article in journal (Refereed)
    Abstract [en]

    We show that polar codes asymptotically achieve the whole capacity-equivocation region for the wiretap channel when the wiretapper's channel is degraded with respect to the main channel, and the weak secrecy notion is used. Our coding scheme also achieves the capacity of the physically degraded receiver-orthogonal relay channel. We show simulation results for moderate block length for the binary erasure wiretap channel, comparing polar codes and two edge type LDPC codes.

  • 199.
    Andersson, Mattias
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Schaefer, Rafael F.
    Oechtering, Tobias J.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Polar Coding for Bidirectional Broadcast Channels with Common and Confidential Messages2013In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 31, no 9, p. 1901-1908Article in journal (Refereed)
    Abstract [en]

    The integration of multiple services such as the transmission of private, common, and confidential messages at the physical layer is becoming important for future wireless networks in order to increase spectral efficiency. In this paper, bidirectional relay networks are considered, in which a relay node establishes bidirectional communication between two other nodes using a decode-and-forward protocol. In the broadcast phase, the relay transmits additional common and confidential messages, which then requires the study of the bidirectional broadcast channel (BBC) with common and confidential messages. This channel generalizes the broadcast channel with receiver side information considered by Kramer and Shamai. Low complexity polar codes are constructed that achieve the capacity region of both the degraded symmetric BBC, and the BBC with common and confidential messages. The use of polar codes allows an intuitive interpretation of how to incorporate receiver side information and secrecy constraints as different sets of frozen bits at the different receivers for an optimal code design. In order to show that the constructed codes achieve capacity, a tighter bound on the cardinality of an auxiliary random variable used in the converse is found using a method by Salehi.

  • 200.
    Andersson, Mattias
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Zaidi, Syed Ali Abbas
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Wernersson, Niklas
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Nonlinear distributed sensing for closed-loop control over Gaussian channels2011In: Communication Technologies Workshop (Swe-CTW), 2011 IEEE Swedish, IEEE conference proceedings, 2011, p. 19-23Conference paper (Refereed)
    Abstract [en]

    A scenario of distributed sensing for networked control systems is considered and a new approach to distributed sensing and transmission is presented. The state process of a scalar first order linear time invariant dynamical system is sensed by a network of wireless sensors, which then instantaneously transmit their measurements to a remotely situated control unit over parallel Gaussian channels. The control unit aims to stabilize the system in mean square sense. The proposed non-linear delay-free sensing and transmission strategy is compared with the well-known amplify-and-forward strategy, using the LQG control cost as a figure of merit. It is demonstrated that the proposed nonlinear scheme outperforms the best linear scheme even when there are only two sensors in the network. The proposed sensing and transmission scheme can be implemented with a reasonable complexity and it is shown to be robust to the uncertainties in the knowledge of the sensors about the statistics of the measurement noise and the channel noise.

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