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  • 1.
    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.

  • 2.
    Arvidsson, Bertil
    et al.
    Fiberson AB.
    Jason, Johan
    Fiberson AB.
    Alexandersson, Robert
    Ericsson AB.
    Aspects of OTDR Measurements in a Cable Factory2009In: 9th OFMC Conference Digest, 2009, p. 113-117Conference paper (Other academic)
    Abstract [en]

    We will present OTDR-use in an optical cable factory with different types of applications. Doing this we will also present important instrument features and properties in an objective approach. The main reason for this work is to find a simplified use of the OTDR as regards to calibration and attenuation described in IEC 61746. One additional tool, which supports the approach, is to perform random round robin measurements between the fibre supplier and the cable factory.  Therefore, the two relevant topics will be: length calibration and attenuation measurement accuracy. In addition length accuracy will be discussed. This will then be followed by conclusions, which can be summarized as follows: The simplified OTDR-technique is well suited for use in a cable factory and in doing so both time and cost will be saved.

  • 3.
    Barac, Filip
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Caiola, Stefano
    Natl Instruments Italy, I-20090 Milan, Italy.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Sisinni, Emiliano
    Univ Brescia, Dept Informat Engn, I-25123 Brescia, Italy.
    Zhang, Tingting
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Channel Diagnostics for Wireless Sensor Networks in Harsh Industrial Environments2014In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 14, no 11, p. 3983-3995Article in journal (Refereed)
    Abstract [en]

    Wireless sensor network communication in industrial environments is compromised by interference, multipath fading, and signal attenuation. In that respect, accurate channel diagnostics is imperative to selecting the adequate countermeasures. This paper presents the lightweight packet error discriminator (LPED) that infers the wireless link condition by distinguishing between errors caused by multipath fading and attenuation, and those inflicted by interfering wideband single-channel communication systems (e.g., IEEE 802.11b/g), based on the differences in their error footprints. The LPED uses forward error correction in a novel context, namely, to determine the symbol error density, which is then fed to a discriminator for error source classification. The classification criteria are derived from an extensive set of error traces collected in three different types of industrial environments, and verified on a newly collected set of error traces. The proposed solution is evaluated both offline and online, in terms of classification accuracy, speed of channel diagnostics, and execution time. The results show that in ≥91% of cases, a single packet is sufficient for a correct channel diagnosis, accelerating link state inference by at least 270%, compared with the relevant state-of-the-art approaches. The execution time of LPED, for the worst case of packet corruption and maximum packet size, is below 30 ms with ≤3% of device memory consumption. Finally, live tests in an industrial environment show that LPED quickly recovers from link outage, by losing up to two packets on average, which is only one packet above the theoretical minimum.

  • 4.
    Barac, Filip
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Zhang, Tingting
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Channel Coding and Interleaving in Industrial WSN: Abiding to Timing Constraints and Bit Error Nature2013In: Proceedings - M and N 2013: 2013 IEEE International Workshop on Measurements and Networking, 2013, p. 46-51Conference paper (Refereed)
    Abstract [en]

    Forward Error Correction is a preemptive manner of improving communication reliability. Albeit not a part of IEEE 802.15.4-2006 standard, its application in Industrial Wireless Sensor Networks has been widely considered. Nevertheless, this study is the first performance analysis on real error traces with sufficiently lightweight channel codes, with respect to IEEE 802.15.4-2006 and industrial wireless communication timing constraints. Based on these constraints and bit error properties from the collected traces, the use of Reed-Solomon (15,7) block code is suggested, which can be implemented in software. Experiments show that bit error nature on links affected by multipath fading and attenuation in industrial environments is such that RS(15,7) can correct ≥95% of erroneously received packets, without the necessity for interleaving. On links under IEEE 802.11 interference, typically up to 50% of corrupted packets can be recovered by combining RS(15,7) with symbol interleaving, which has proven to be more effective than its bit counterpart. The optimal interleaving depth is found empirically and it is shown that simple bit-interleaved 1/3 repetition code achieves at least 90% of correcting performance of RS(15,7) code on uninterfered links that operate ≥10 dB above the sensitivity threshold.

  • 5.
    Barac, Filip
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Zhang, Tingting
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    CLAP: Chip-Level Augmentation of IEEE 802.15.4 PHY for Error-Intolerant WSN Communication2015In: IEEE Vehicular Technology Conference, Glasgow, Scotland: IEEE Vehicular Technology Society , 2015, p. 1-7Conference paper (Refereed)
    Abstract [en]

    Communication reliability is the ultimate priority in safety-critical wireless sensor network (WSN) communication. Surprisingly enough, the enormous potential of error control on direct sequence spread spectrum (DSSS) chips in IEEE 802.15.4 has been completely overlooked by the WSN community, possibly due to incorrect presumptions, such as the concerns about computational overhead. Current error-correction schemes in WSN counteract the error process once the errors have already propagated to bit- and packet-level. Motivated by the notion that errors should be confronted at the earliest stage, this work presents CLAP, a novel method that tremendously improves the error correction in WSN by fortifying the IEEE 802.15.4 Physical layer (PHY) with straightforward manipulations of DSSS chips. CLAP is implemented on a software-defined radio platform, and evaluated on real error traces from heavily WLAN-interfered IEEE 802.15.4 transmissions at 3 different environments. CLAP boosts the number of corrected packets by 1.78-6.88 times on severely interfered links, compared to two other state-of-the-art schemes. The overhead in terms of computational complexity is about 10% of execution time of the OQPSK demodulator in the legacy IEEE 802.15.4 receiver chain.

  • 6.
    Barac, Filip
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Zhang, Tingting
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    PREED: Packet Recovery by Exploiting the Determinism in Industrial WSN Communication2015In: Proceedings - IEEE International Conference on Distributed Computing in Sensor Systems, DCOSS 2015, Fortaleza, Brazil: IEEE Computer Society, 2015, p. 81-90Conference paper (Refereed)
    Abstract [en]

    The requirements of safety-critical wireless sensornetwork (WSN) applications, such as closed-loop control andtraffic safety, cannot be met by the IEEE 802.15.4-2006 standardnor its industrial WSN (IWSN) derivatives. The main problem inthat respect is the communication reliability, which is seriouslycompromised by 2.4-GHz interference, as well as multipathfading and attenuation (MFA) at industrial facilities. Meanwhile,communication blackouts in critical WSN applications maylead to devastating consequences, including production halts,damage to production assets and can pose a threat to safetyof human personnel. This work presents PREED, a method toimprove the reliability by exploiting the determinism in IWSNcommunication. The proposed solution is based on the analysisof bit error traces collected in real transmissions at four differentindustrial environments. A case study on WirelessHART packetformat shows that PREED recovers 42%-134% more packetsthan the competing approaches on links compromised by WLANinterference. In addition, PREED reduces one of the most trivialcauses of packet loss in IWSN, i.e. the corruption offrame lengthbyte, by 88% and 99%, for links exposed to WLAN interferenceand MFA, respectively.

  • 7.
    Barac, Filip
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Zhang, Tingting
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Ubiquitous, yet Deceptive: Hardware-Based Channel Metrics on Interfered WSN Links2015In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 64, no 5, p. 1766-1778Article in journal (Refereed)
    Abstract [en]

    The ease of acquiring hardware-based link quality indicators is an alluring property for fast channel estimation in time- and safety-critical Wireless Sensor Network (WSN) applications, such as closed-loop control and interlocking. The two rudimentary hardware-based channel quality metrics, Received Signal Strength (RSS) and Link Quality Indicator (LQI), are the key constituents of channel estimation and a plethora of other WSN functionalities, from routing to transmit power control. Nevertheless, this study highlights three deficient aspects of these two indicators: 1) overall deceptiveness, i.e. the inability to reveal the presence of interference, falsely indicating excellent channel conditions in an unacceptably high fraction of cases; 2) the burstiness of missed detections, which compromises the attempts to eliminate the deceptiveness by averaging; 3) high mutual discrepancy of the two indicators, observed in 39-73% of packets, throughout different scenarios. The ability of RSS and LQI to indicate IEEE 802.11 interference is scrutinized in a variety of scenarios in typical industrial environments, using commercialoff- the-shelf hardware and realistic network topologies, giving the findings of this study a high general validity and practical relevance.

  • 8.
    Barac, Filip
    et al.
    Ericsson AB.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Zhang, Tingting
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Sisinni, Emiliano
    University of Brescia.
    Error Manifestation in Industrial WSN Communication and Guidelines for Countermeasures2017In: Wireless Sensor Systems for Extreme Environments: Space, Underwater, Underground and Industrial / [ed] H. F. Rashvand and A. Abedi, John Wiley & Sons, 2017Chapter in book (Refereed)
  • 9.
    Barac, Filip
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media. ABB Corporate Research, Sweden.
    Åkerberg, Johan
    ABB Corporate Research, Sweden.
    A Lightweight Routing Protocol for Industrial Wireless Sensor and Actuator Networks2011In: Proceedings of IECON 2011 - 37th Annual Conference on IEEE Industrial Electronics Society, Melbourne, Australia: IEEE Industrial Electronics Society , 2011, p. 2980-2985Conference paper (Refereed)
    Abstract [en]

    The applications of Industrial Wireless Sensor and Actuator Networks (IWSAN) are time-critical and subject to strict requirements in terms of end-to-end delay and reliability of data delivery. A notable shortcoming of the existing wireless industrial communication standards is the existence of overcomplicated routing protocols, whose adequacy for the intended applications is questionable [1]. This paper evaluates the potentials of flooding as a data dissemination technique in IWSANs. The concept of flooding is recycled by introducing minimal modifications to its generic form and compared with a number of existing WSN protocols, in a variety of scenarios. The simulation results of all scenarios observed show that our lightweight approach is able to meet stringent performance requirements for networks of considerable sizes. Furthermore, it is shown that this solution significantly outperforms a number of conventional WSN routing protocols in all categories of interest.

  • 10.
    Barac, Filip
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Yu, Kan
    Mälardalen University College, Sweden.
    Gidlund, Mikael
    ABB AB, Corporate Research, Sweden.
    Åkerberg, Johan
    ABB AB, Corporate Research, Sweden.
    Björkman, Mats
    Mälardalen University College, Sweden.
    Towards Reliable and Lightweight Communication in Industrial Wireless Sensor Networks2012In: Procedings of the IEEE 10th International Conference on Industrial Informatics, INDIN 2012, IEEE conference proceedings, 2012, p. 1218-1224Conference paper (Refereed)
    Abstract [en]

    In this paper we address the issues of timeliness and transmission reliability of existing industrial communication standards. We combine a Forward Error Correction coding scheme on the Medium Access Control layer with a lightweight routing protocol to form an IEEE 802.15.4-conformable solution, which can be implemented into already existing hardware without violating the standard. After laying the theoretical foundations, we conduct a performance evaluation of the proposed solution. The results show a substantial gain in reliability and reduced latency, compared to the uncoded transmissions, as well as common Wireless Sensor Network routing protocols.

  • 11.
    Beltramelli, Luca
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Österberg, Patrik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Jennehag, Ulf
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Hybrid MAC Mechanism for Energy Efficient Communication in IEEE 802.11ah2017In: Proceedings of the 2017 IEEE International Conference on Industrial Technology (ICIT), IEEE, 2017, p. 1295-1300, article id 7915550Conference paper (Refereed)
    Abstract [en]

    Many applications for machine-to-machine (M2M) communications are characterized by large numbers of devices with sporadic transmissions and subjected to low energy budgets. This work addresses the importance of energy consumption by proposing a new Medium Access Control (MAC) mechanism for improving the energy efficiency of IEEE 802.11ah, a standard targeting M2M communication. We propose to use the features of IEEE 802.11ah MAC to realize a hybrid contention-reservation mechanism for the transmission of uplink traffic. In the proposed mechanism, any device with a buffered packet will first notify the Access Point (AP) during a contention phase before being given a reserved timeslot for the data transmission. We develop a mathematical model to analyse the energy consumption ofthe proposed mechanism and of IEEE 802.11ah. The results show that for a monitoring scenario, the proposed contention reservation mechanism reduces the energy consumption for a successful uplink data transmission by up to 55%.

  • 12. Campadello, Stefano
    et al.
    Coutand, Olivier
    Ebben, Peter
    van Eijk, Ronald
    Hjelm, Johan
    Holtmanns, Silke
    Kanter, Theo
    Ericsson Research.
    Privacy, Trust and Group Communications2007In: Enabling Technologies for Mobile Services: The MobiLife Book, John Wiley & Sons, 2007Chapter in book (Other academic)
  • 13.
    Engelke, U.
    et al.
    Commonwealth Scientific and Industrial Research Organisation (CSIRO), Hobart, Australia.
    Darcy, D.P.
    Dolby Laboratories, San Francisco, USA.
    Mulliken, G.H.
    Dolby Laboratories, San Francisco, USA.
    Bosse, S.
    Fraunhofer Institute for Telecommunications, Berlin, Germany.
    Martini, M.G.
    Kingston University, London, UK.
    Arndt, S.
    Norwegian University of Science and Technology (NTNU), Trondheim, Norway.
    Antons, J.-N.
    Technische Universiat Berlin, Germany.
    Chan, K.Y.
    Curtin University, Perth, Australia.
    Ramzan, N.
    University of the West of Scotland, Hamilton, UK.
    Brunnström, Kjell
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems. Acreo Swedish ICT AB.
    Psychophysiology-based QoE Assessment: A Survey2017In: IEEE Journal on Selected Topics in Signal Processing, ISSN 1932-4553, E-ISSN 1941-0484, Vol. 11, no 1, p. 6-21, article id 7569001Article in journal (Refereed)
    Abstract [en]

    We present a survey of psychophysiology-based assessment for Quality of Experience (QoE) in advanced multimedia technologies. We provide a classification of methods relevant toQoE and describe related psychological processes, experimental design considerations, and signal analysis techniques. We summarise multimodal techniques and discuss several important aspects of psychophysiology-based QoE assessment, including the synergies with psychophysical assessment and the need for standardised experimental design. This survey is not considered to be exhaustive but serves as a guideline for those interested to further explore this emerging field of research.

  • 14.
    Eriksson, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Packet and Resource Plan Scheduling (PARPS) - with Application to Mobile IP over DVB-T2000In: Proceedings of The 2000 International Conference on Broadband Wireless Access Systems (WAS2000), 4-6 December 2000, San Francisco, U.S.A. / [ed] Willie W. LU, 2000Conference paper (Other academic)
    Abstract [en]

    The Terrestrial Digital Video Broadcasting system (DVB-T) can be utilized as a supplemental broadband downlink to today´s cellular systems. Thus, mobile Internet access with downstream peek bit rates of 10 to 30 Mbit/s can be achieved. To make this concept competitive in comparison to for example UMTS, efficient Radio Resource Management (RRM) is essential. Schemes for downlink dynamic RRM on a packet-by-packet basis are suggested and evaluated for a simplified packet data model. Packet and Resource Plan Scheduling (PARPS) schemes reduce the problem of finding an optimized combination of several RRM parameters to a scheduling problem. Dynamic Single Frequency Networks (DSFN) and Virtual Cellular Networks (VCN) exploits the macro-diversity capability of the OFDM modulation scheme by dynamically forming groups of transmitters that send the same information on the same frequency channel simultaneously. Dynamic Packet Assignment (DPA) is a combination of Dynamic Channel Assignment (DCA) and packet scheduling. The Fairly Shared Spectrum Efficiency (FSSE), in bit/s/Hz/transmitter site, is improved by up to 370% for a certain test cases, by the DSFN scheme in comparison to DPA.

  • 15.
    Eriksson, Magnus
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Xu, Youzhi
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Packet-by-packet Radio Resource Management by means of Dynamic Single Frequency Networks: The 2000 International Conference on Broadband Wireless Access Systems (WAS'00), San Fransisco, U.S.A., December 4-6, 20002000Conference paper (Other academic)
    Abstract [en]

    By combining a cellular system with the terrestrial digital video broadcasting system (DVB-T), wide-area asymmetric Internet access can be achieved, with a downlink peak bit rate of 10-20Mbps. In this paper, we study dynamic resource management on a packet-by-packet basis for this broadband downlink. A model for best-effort traffic is proposed, which simplifies the evaluation of maximum throughput and fairness. Dynamic Single Frequency Networks (DSFN) are evaluated, which exploits the macrodiversity capability of the OFDM modulation scheme. The transmitters are divided into single frequency networks (SFNs), i.e. groups of transmitters that send the same information at the same channel frequency simultaneously. An algorithm changes the SFN grouping from timeslot to timeslot, and schedules the packets. DSFN is a way of introducing timeslots and Dynamic Channel Allocation into DVB-T, without keying of the transmitter power. Thus, receiver and transmitter circuits existing on the market today can be used, and only software modifications are required. A spectrum efficiency of 0.45 bit/s/Hz/site is achieved with omni-directional antennas under certain conditions. This is a capacity improvement of 170% in comparison to a Fixed Channel Allocation solution with static handover.

  • 16.
    Ferrari, P.
    et al.
    University of Brescia, Italy.
    Flammini, A.
    University of Brescia, Italy.
    Rizzi, M.
    University of Brescia, Italy.
    Sisinni, Emiliano
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology. University of Brescia, Italy.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    On the evaluation of LoRaWAN virtual channels orthogonality for dense distributed systems2017In: 2017 IEEE International Workshop on Measurement and Network (M&N), IEEE, 2017, p. 85-90, article id 8078371Conference paper (Refereed)
    Abstract [en]

    Internet of Things (IoT) aims at collecting data from billions of devices connected altogether. Despite there is no one technology able to cope with all possible scenarios, LPWAN solutions are emerging as viable technologies for implementing private, low-cost cellular like wireless networks. Distributed systems could leverage this approach as a driving technology for services as smart environment sensing, pervasive sensing and soon. In the considered scenario, the capacity of the network is of main importance; even if communication is sporadic for most of the time, an event observed by many nodes results in a huge amount of simultaneous transmissions. Are the IoT technologies usable to this end? In this paper LoRaWAN technology is investigated, with the aim of evaluating the orthogonality of virtual channels permitted by the LoRa physical layer. In particular, measurements demonstrated that overlapping transmissions having the same power at the receiver can be correctly decoded if occurring with different spreading factors, whereas co-spread messages require at least 4ms spacing.

  • 17.
    Gidlund, Mikael
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Lennvall, Tomas
    RISE SICS Västerås.
    Åkerberg, Mikael
    ABB Corporate Research.
    Will 5G Become Yet Another Wireless Technologyfor Industrial Automation?2017In: Proceedings of the 2017 IEEE International Conference on Industrial Technology (ICIT), IEEE, 2017, p. 1319-1324, article id 7915554Conference paper (Refereed)
    Abstract [en]

    With the growing interest in adoption of wireless technologies in industrial automation and the continuous search for new revenue streams new players are entering the arena in order to make their business grow further. One of the emerging wireless technologies aiming to support industrial automation applications is 5G, targeting anything from extreme throughput (>10 Gbit/s) to extreme low latency (< 1 ms) to ultra high reliability (>99.999%). In this article we intend to discuss the potential and challenges of adopting 5G in real industrial environments and give a more balanced picture compared to previous articles mainly written by telecom researchers and vendors as a way to promote their technology. Specifically, this article will discuss and provide some real industrial requirements, describe the main technical features of 5G and try to assess what applications it will support that are not by already supported by existing technologies. In the end, the success of 5G will depend on appealing business models and scalability, i.e., whether or not the same equipment can be deployed worldwide without any changes and spectrum rules, and the migration paths beyond 5G for reasonable business risks.

  • 18.
    Grimaldi, Simone
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Mahmood, Aamir
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    An SVM-Based Method for Classification of External Interference in Industrial Wireless Sensor and Actuator Networks2017In: Journal of Sensor and Actuator Network, ISSN 2224-2708, Vol. 6, no 2, article id 9Article in journal (Refereed)
    Abstract [en]

    In recent years, the adoption of industrial wireless sensor and actuator networks (IWSANs) has greatly increased. However, the time-critical performance of IWSANs is considerably affected by external sources of interference. In particular, when an IEEE 802.11 network is coexisting in the same environment, a significant drop in communication reliability is observed. This, in turn, represents one of the main challenges for a wide-scale adoption of IWSAN. Interference classification through spectrum sensing is a possible step towards interference mitigation, but the long sampling window required by many of the approaches in the literature undermines their run-time applicability in time-slotted channel hopping (TSCH)-based IWSAN. Aiming at minimizing both the sensing time and the memory footprint of the collected samples, a centralized interference classifier based on support vector machines (SVMs) is introduced in this article. The proposed mechanism, tested with sample traces collected in industrial scenarios, enables the classification of interference from IEEE 802.11 networks and microwave ovens, while ensuring high classification accuracy with a sensing duration below 300 ms. In addition, the obtained results show that the fast classification together with a contained sampling frequency ensure the suitability of the method for TSCH-based IWSAN

  • 19.
    Guntupalli, Lakshmikanth
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Multiple Packet Transmissions in Duty Cycling WSNs: A DTMC Based Throughput Analysis2017In: IEEE Wireless Communications Letters, ISSN 2162-2337, E-ISSN 2162-2345Article in journal (Refereed)
    Abstract [en]

    Multiple packet transmissions (MPT) improve performance by transmitting multiple packets in a single operational cycle. Asynchronous duty cycling (DC) medium access control (MAC) protocols such as receiver initiated MAC protocol (RI-MAC) transmit multiple packets in one cycle. In this paper, we develop two associated discrete time Markov chain (DTMC) models to model MPT that can be achieved via multiple node competitions. Furthermore, we present the way of incorporating those developed models with each other for evaluating performance of RI-MAC with MPT. Using the solution of DTMC models, network throughput of MPT is calculated and compared with the one achieved by single packet transmission MAC (e.g., S-MAC) protocol. Validation of analytical results through discrete-event simulations confirms the accuracy of modeling and discloses the operation of MPT in RI-MAC protocol. 

  • 20.
    Guntupalli, Lakshmikanth
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology. University of Agder, Norway.
    Li, Frank
    University of Agder, Norway.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Energy Harvesting Powered Packet Transmissions in Duty-cycled WSNs: A DTMC Analysis2017In: Proc. of IEEE GLOBECOM'17, Singapore, Dec. 2017, IEEE, 2017Conference paper (Refereed)
    Abstract [en]

    Energy harvesting (EH) promises an extended lifetime for wireless sensor networks (WSNs), supplying sensor nodes with accumulated energy from natural sources. Different from battery powered sensors, nodes in EH-enabled WSNs are equipped with an energy harvesting accessory in order to extract energy from surrounding sources. Based upon the harvested energy, sensor nodes perform data exchange activities. In this paper, we develop two discrete time Markov chain (DTMC)models to analyze the performance of packet transmissionsin such a WSN while employing a generic medium access control (MAC) protocol. Using the proposed DTMC models, we investigate the effect of EH over a synchronous MAC protocol with respect to average packet delay and network throughput. Furthermore, the analytical results are validated via discrete event simulations. Numerical results indicate the accuracy of the models and reveal the behavior of packet transmissions relying on harvested energy.

  • 21.
    Gustavsson, Klas
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Olsson, Leif
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Andersson, U
    SOS Alarm Sverige AB, Stockholm, Sweden.
    Simulating traffic management strategies at the Swedish emergency call centerIn: Article in journal (Refereed)
    Abstract [en]

    In telecommunication research, the assessment of strategic and operational performance has gained a lot of interest. So far, the variability within the operational research of telecommunication derives from the stochastic nature of call arrivals, call duration and abandonments. This study extends the stochastic drivers to capacity by incorporating agent behavior. In this study, we model a Discrete-Event-Simulation model of the Swedish emergency call service provider to assist the strategic issue of skills-based routing. Because of the pull system, we designed skills-based routing using an event-dependent overflow setting with a fixed waiting time threshold, where calls become visible to extended agent classes after a threshold value, providing an advantage to primary idle agents to answer before idle secondary agents. Our model mimics the tail of waiting times better than conventional methods. Because of the accompanied calculation opportunities, the model has assisted both strategic and operational issues in the organization. In addition to practical implications, the study proves that the stochastic nature of agent behavior is crucial. From a queueing theory perspective, the study provides interesting routing effects for an event-dependent overflow setting using a fixed waiting time threshold in a combined “X-N-design”, previously unexplored in research.

  • 22.
    Jason, Johan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Fibre-Optic Displacement and Temperature Sensing Using Coupling Based Intensity Modulation and Polarisation Modulation Techniques2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Optical fibre sensors are employed in the measurements of a number of different physical properties or for event detection in safety and security systems. In those environments which suffer from electromagnetic disturbance, in harsh environments where electronics cannot survive and in applications in favour of distributed detection, fibre-optic sensors have found natural areas of use. In some cases they have replaced conventional electronic sensors due to better performance and long-term reliability, but in others they have had less success mainly due to the higher costs which are often involved in fibre-optic sensor systems.

    Intensity modulated fibre-optic sensors normally require only low-cost monitoring systems principally based on light emitting diodes and photodiodes. The sensor principle itself is very elemental when based on coupling between fibres, and coupling based intensity modulated sensors have been utilised over a long period of time, mainly within displacement and vibration sensing. For distributed sensing based on intensity modulation, optical time domain reflectometer (OTDR) systems with customised sensor cables have been used in the detection of heat, water leakage and hydrocarbon fluid spills.

    In this thesis, new concepts for intensity modulated fibre-optic sensors based on coupling between fibres are presented, analysed, simulated and experimentally verified. From a low-cost and standard component perspective, alternative designs are proposed and analysed using modulation function simulations and measurements, in order to find an improved performance. Further, the development and installation of a temperature sensor system for industrial process monitoring is presented, involving aspects with regards to design, calibration, multiplexing and fibre network installation. The OTDR is applied as an efficient technique for multiplexing several coupling based sensors, and sensor network installation with blown fibre in microducts is proposed as a flexible and cost-efficient alternative to traditional cabling.

    As a solution to alignment issues in coupling based sensors, a new displacement sensor configuration based on a fibre to a multicore fibre coupling and an image sensor readout system is proposed. With this concept a high-performance sensor setup with relaxed alignment demands and a large measurement range is realised. The sensor system performance is analysed theoretically with complete system simulations, and an experimental setup is made based on standard fibre and image acquisition components. Simulations of possible error contributions show that the experimental performance limitation is mainly related to differences between the modelled and the real coupled power distribution. An improved power model is suggested and evaluated experimentally, showing that the experimental performance can be improved down towards the theoretical limit of 1 μm.

    The potential of using filled side-hole fibres and polarisation analysis for point and distributed detection of temperature limits is investigated as a complement to existing fibre-optic heat detection systems. The behaviour and change in birefringence at the liquid/solid phase transition temperature for the filler substance is shown and experimentally determined for side-hole fibres filled with water solutions and a metal alloy, and the results are supported by simulations. A point sensor for on/off temperature detection based on this principle is suggested. Further the principles of distributed detection by measurements of the change in beat length are demonstrated using polarisation OTDR (POTDR) techniques. It is shown that high-resolution techniques are required for the fibres studied, and side-hole fibres designed with lower birefringence are suggested for future studies in relation to the distributed application.

  • 23.
    Jason, Johan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Nilsson, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Arvidsson, Bertil
    Fiberson AB, Fibervagen 2, Hudiksvall SE-824 11, Sweden.
    Larsson, Anders
    Fiberson AB, Fibervagen 2, Hudiksvall SE-824 11, Sweden.
    Robustness analysis of an intensity modulated fiber-optic position sensor with an image sensor readout system2013In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 52, no 16, p. 3876-3883Article in journal (Refereed)
    Abstract [en]

    An intensity modulated fiber-optic position sensor, based on a fiber to bundle coupling and a readout system using a CMOS image camera together with fast routines for position extraction and calibration, is presented and analyzed. The proposed system eliminates alignment issues otherwise associated with coupling based fiber-optic sensors, still keeping the sensing point free from detector electronics. In this study the robustness of the system is characterized through simulations of the system performance, and the outcome is compared with experimental results. It is shown that knowledge of the shape of the coupled power distribution is the single most important factor for high performance of the system. Further it is experimentally shown that the position extraction error can be improved down to the theoretical limit by employing a modulation function model well fitted to the real coupled power distribution.

  • 24.
    Jason, Johan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design. Fiberson AB, SE-82450 Hudiksvall, Sweden.
    Rugeland, Patrik
    Acreo Swedish ICT AB, SE-16440 Stockholm, Sweden.
    Tarasenko, Oleksandr
    Acreo Swedish ICT AB, SE-16440 Stockholm, Sweden.
    Margulis, Walter
    Acreo Swedish ICT AB, SE-16440 Stockholm, Sweden.
    Nilsson, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Temperature characteristics of the birefringence properties of filled side-hole fibers2013In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 52, no 21, p. 5208-5215Article in journal (Refereed)
    Abstract [en]

    The temperature characteristics of the birefringence of side-hole fibers filled with liquids or metal are investigated, aiming at providing a basis for on/off temperature sensing. Short pieces of fiber are filled and the change in birefringence is registered using measurements in reflective mode of the transmitted power through a linear polarizer at 1550 nm. The rapid change in the birefringence behavior of the fiber at the temperature of the phase transition of the filler substance is shown, and from the measurement data the phase transition temperatures can be determined as well as an estimation of the birefringence change with temperature. The experimental results are supported by numerical simulations.

  • 25.
    Kandukuri, Somasekhar Reddy
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Power Control Mechanisms on WARP Boards2013Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    In recent years, a number of power control concepts have been studied and implementedeither in simulation or in practice for different communication systems. It is still the case that a great deal of research is being conducted within the area of energyefficient power control mechanisms for future wireless communication networksystems. However, only a limited amount of practical work has been implemented onreal test beds environment. The main goal of this thesis is to propose and develop newprototype Transmit Power Control Mechanisms (TPCM) on WARP (Wireless Open-Access Research Platform) boards for point-to-point communications, which are to bedeveloped and tested in an indoor environment. This work mainly focuses on the automaticpower control nodes, transmission and reception over-the-air. In this thesis, wehave designed and developed TPCM to adjust the power levels on a transmitter nodeby following the feedback (ACK) approach. In this case, the destination (receiver)node always sends the feedback (ACK) to transmitter node during every successfultransmission of message signal and the main focus is on a reduction in the packetloss rate (PLR), an increase in the packet reception rate (PRR) and the capacity ofthe nodes. In this real work, we have developed and measured the results based ontwo functions namely, with and without packet window function power control mechanisms.

    According to the measurements section, both with and without function powercontrol mechanisms proved to have better performances for different tunable parameters.If both functions are compared, then the with window function power controlmechanism was shown to produce better performances than the without windowpower control mechanism and it also converged faster than the without window function.If consideration was given to controlling a reduction in packet loss rate, thenthe with widnow function offered higher performances than those without the windowfunction. In this regard, it was found that the with window function has acheived amaximum packet reception rate than that for the without window function for differenttunable parameters. In relation to the power consumption scenario, it was determinedthat the without window fuction proved to produce energy saving performances thanthe with window function. There are several interesting aspects of the transmit powercontrol mechanisms highlighted in the results and discussion chapter.

  • 26.
    Lennvall, Tomas
    et al.
    ABB Corporate Research.
    Frey, Jan-Erik
    ABB AB, Substation Automation.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Wireless Sensor Networks for Automation2014In: Industrial Communication Technology Handbook / [ed] R. Zurawski, CRC Press, 2014, 2Chapter in book (Refereed)
  • 27.
    Lennvall, Tomas
    et al.
    ABB Corporate Research.
    Landernäs, Krister
    ABB Corporate Research.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Åkerberg, Johan
    ABB Corporate Research.
    Industrial WSN Standards2013In: Industrial Wireless Sensor Networks: Applications, Protocols, and Standards / [ed] V. C. Güngör and G. P. Hancke, USA: CRC Press, 2013Chapter in book (Refereed)
  • 28.
    Li, Yun
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Sjöström, Mårten
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Olsson, Roger
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Coding of plenoptic images by using a sparse set and disparities2015In: Proceedings - IEEE International Conference on Multimedia and Expo, IEEE conference proceedings, 2015, p. -Art. no. 7177510Conference paper (Refereed)
    Abstract [en]

    A focused plenoptic camera not only captures the spatial information of a scene but also the angular information. The capturing results in a plenoptic image consisting of multiple microlens images and with a large resolution. In addition, the microlens images are similar to their neighbors. Therefore, an efficient compression method that utilizes this pattern of similarity can reduce coding bit rate and further facilitate the usage of the images. In this paper, we propose an approach for coding of focused plenoptic images by using a representation, which consists of a sparse plenoptic image set and disparities. Based on this representation, a reconstruction method by using interpolation and inpainting is devised to reconstruct the original plenoptic image. As a consequence, instead of coding the original image directly, we encode the sparse image set plus the disparity maps and use the reconstructed image as a prediction reference to encode the original image. The results show that the proposed scheme performs better than HEVC intra with more than 5 dB PSNR or over 60 percent bit rate reduction.

  • 29.
    Li, Yun
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Sjöström, Mårten
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Olsson, Roger
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Jennehag, Ulf
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Coding of focused plenoptic contents by displacement intra prediction2016In: IEEE transactions on circuits and systems for video technology (Print), ISSN 1051-8215, E-ISSN 1558-2205, Vol. 26, no 7, p. 1308-1319, article id 7137669Article in journal (Refereed)
    Abstract [en]

    A light field is commonly described by a two-plane representation with four dimensions. Refocused three-dimensional contents can be rendered from light field images. A method for capturing these images is by using cameras with microlens arrays. A dense sampling of the light field results in large amounts of redundant data. Therefore, an efficient compression is vital for a practical use of these data. In this paper, we propose a displacement intra prediction scheme with a maximum of two hypotheses for the compression of plenoptic contents from focused plenoptic cameras. The proposed scheme is further implemented into HEVC. The work is aiming at coding plenoptic captured contents efficiently without knowing underlying camera geometries. In addition, the theoretical analysis of the displacement intra prediction for plenoptic images is explained; the relationship between the compressed captured images and their rendered quality is also analyzed. Evaluation results show that plenoptic contents can be efficiently compressed by the proposed scheme. Bit rate reduction up to 60 percent over HEVC is obtained for plenoptic images, and more than 30 percent is achieved for the tested video sequences.

  • 30.
    Li, Yun
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Sjöström, Mårten
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Olsson, Roger
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Jennehag, Ulf
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Scalable coding of plenoptic images by using a sparse set and disparities2016In: IEEE Transactions on Image Processing, ISSN 1057-7149, E-ISSN 1941-0042, Vol. 25, no 1, p. 80-91, article id 7321029Article in journal (Refereed)
    Abstract [en]

    One of the light field capturing techniques is the focused plenoptic capturing. By placing a microlens array in front of the photosensor, the focused plenoptic cameras capture both spatial and angular information of a scene in each microlens image and across microlens images. The capturing results in significant amount of redundant information, and the captured image is usually of a large resolution. A coding scheme that removes the redundancy before coding can be of advantage for efficient compression, transmission and rendering. In this paper, we propose a lossy coding scheme to efficiently represent plenoptic images. The format contains a sparse image set and its associated disparities. The reconstruction is performed by disparity-based interpolation and inpainting, and the reconstructed image is later employed as a prediction reference for the coding of the full plenoptic image. As an outcome of the representation, the proposed scheme inherits a scalable structure with three layers.The results show that plenoptic images are compressed efficiently with over 60 percent bit rate reduction compared to HEVC intra, and with over 20 percent compared to HEVC block copying mode.

  • 31.
    Lo Bello, Lucia
    et al.
    University of Catania, Italy.
    Åkerberg, Johan
    ABB Corporate Research, Sweden.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Uhlemann, Elisabeth
    Mälardalen University.
    Guest Editorial Special Section on New Perspectives on Wireless Communications in Automation: From Industrial Monitoring and Control to Cyber-Physical Systems2017In: IEEE Transactions on Industrial Informatics, ISSN 1551-3203, E-ISSN 1941-0050, Vol. 13, no 3, p. 1393-1397, article id 7938563Article in journal (Refereed)
  • 32.
    Ma, Jian
    et al.
    Beijing Jiatong University, China.
    Yang, Dong
    Beijing Jiatong University, China.
    Zhang, Honke
    Beijing Jiatong University, China.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    A Reliable Handoff Mechanism for Mobile Industrial Wireless Sensor Networks2017In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 17, no 8, article id 1797Article in journal (Refereed)
    Abstract [en]

    With the prevalence of low-power wireless devices in industrial applications, concerns about timeliness and reliability are bound to continue despite the best efforts of researchers to design Industrial Wireless Sensor Networks (IWSNs) to improve the performance of monitoring and control systems. As mobile devices have a major role to play in industrial production, IWSNs should support mobility. However, research on mobile IWSNs and practical tests have been limited due to the complicated resource scheduling and rescheduling compared with traditional wireless sensor networks. This paper proposes an effective mechanism to guarantee the performance of handoff, including a mobility-aware scheme, temporary connection and quick registration. The main contribution of this paper is that the proposed mechanism is implemented not only in our testbed but in a real industrial environment. The results indicate that our mechanism not only improves the accuracy of handoff triggering, but also solves the problem of ping-pong effect during handoff. Compared with the WirelessHART standard and the RSSI-based approach, our mechanism facilitates real-time communication while being more reliable, which can help end-to-end packet delivery remain an average of 98.5% in the scenario of mobile IWSNs.

  • 33.
    Mahmood, Aamir
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Renewal-theoretic Packet Collision Modeling under Long-tailed Heterogenous Traffic2017In: 28th Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC'17), Montreal, Canada, Oct. 2017., IEEE, 2017Conference paper (Refereed)
    Abstract [en]

    Internet-of-things (IoT), with the vision of billions of connected devices, is bringing a massively heterogeneouscharacter to wireless connectivity in unlicensed bands. The heterogeneity in medium access parameters, transmit power and activity levels among the coexisting networks leads to detrimental cross-technology interference.The stochastic traffic distributions, shaped under CSMA/CA rules, of an interfering network and channel fading makes it challenging to model and analyze the performanceof an interfered network. In this paper, to study the temporal interaction between the traffic distributions of two coexisting networks, we develop a renewal-theoretic packet collision model and derive a generic collision-time distribution (CTD) function of an interfered system. The CTD function holds for any busy- and idle-time distributions of the coexisting traffic. As the earlier studies suggesta long-tailed idle-time statistics in real environments, the developed model only requires the Laplace transform of long-tailed distributions to find the CTD. Furthermore,we present a packet error rate (PER) model under the proposed CTD and multipath fading of the interfering signals. Using this model, a computationally efficient PERapproximation for interference-limited case is developed to analyze the performance of an interfered link.

  • 34.
    Mahmood, Aamir
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Hossain, M. M. Aftab
    KTH Royal Institute of Technology.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Cross-Layer Optimization of Wireless Links under Reliability and Energy Constraints2018Conference paper (Refereed)
    Abstract [en]

    The vision of connecting billions of battery operated devices to be used for diverse emerging applications calls for a wireless communication system that can support stringent reliability and latency requirements. Both reliability and energy efficiency are critical for many of these applications that involve communication with short packets which undermine the coding gain achievable from large packets. In this paper, we study a cross-layer approach to optimize the performance of low-power wireless links. At first, we derive a simple and accurate packet error rate (PER) expression for uncoded schemes in block fading channels based on a new proposition that shows that the waterfall threshold in the PER upper bound in Nakagami-m fading channels is tightly approximated by the m-th moment of an asymptotic distribution of PER in AWGN channel. The proposed PER approximation establishes an explicit connection between the physical and link layers parameters, and the packet error rate. We exploit this connection for cross-layer design and optimization of communication links. To this end, we propose a semi-analytic framework to jointly optimize signal-to-noise ratio (SNR) and modulation order at physical layer, and the packet length and number of retransmissions at link layer with respect to distance under the prescribed delay and reliability constraints.

  • 35.
    Mahmood, Aamir
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Jäntti, Riku
    Aalto University, School of Science and Technology, Department of Communications and Networking, Finland .
    Packet Error Rate Analysis of Uncoded Schemes in Block-Fading Channels using Extreme Value Theory2017In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 21, no 1, p. 208-211, article id 7583696Article in journal (Refereed)
    Abstract [en]

    We present a generic approximation of the packet error rate (PER) function of uncoded schemes in the AWGN channel using extreme value theory (EVT). The PER function can assume both the exponential and the Gaussian Q-function bit error rate (BER) forms. The EVT approach leads us to a best closed-form approximation, in terms of accuracy and computational efficiency, of the average PER in block-fading channels. The numerical analysis shows that the approximation holds tight for any value of SNR and packet length whereas the earlier studies approximate the average PER only at asymptotic SNRs and packet lengths.

  • 36.
    Mahmud, Arif
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
     Transmitter macrodiversity in WSAN and MANET: Energy consumption algorithms for wireless multihop networks2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Three of the most important factors with regards to wireless multi-hop networks, namely reachability, energy consumption and network stability are considered in our transmitter macrodiversity supported broadcasting routing algorithms. Broadcasting applications are not only used to send routing table, queries, programming logic, any specific request etc. to all the nodes from access point but are also capable of playing a vital role in wireless TV distributions and visual sensor networks. All the algorithms are simulated in the MATLAB environment in which the nodes are random and are battery driven on a multi-hop randomized topology. Four new single frequency network (SFN) based algorithms (SFN-A, SFN-B, SFN-C and SFN-D) are formed in order to work over multi-hopping and where three of the algorithms SFN-A, SFN-B and SFN-D bear more or less the same amount of reachability. These three algorithms are able to reach more than 90% of reachability in only Tx power -8dBm whereas non-SFN requires -4dBm and SFN-C requires -2dBm and, in addition can achieve a maximum of 29 percentage points more reachability than the non-SFN algorithm. However, the best algorithm SFN-D consumes a maximum of 58.76% less energy than the SFN-A and a maximum of 14.28% less energy than the SFN-B. The SFN-D algorithm achieves a maximum 3.43 dB diversity gain together with the maximum 37.33% energy consumption gain in comparison to the non-SFN algorithm.

  • 37.
    Olsson, Roger
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Synthesis, Coding, and Evaluation of 3D Images Based on Integral Imaging2008Doctoral thesis, monograph (Other academic)
    Abstract [en]

    In recent years camera prototypes based on Integral Imaging (II) have emerged that are capable of capturing three-dimensional (3D) images. When being viewed on a 3D display, these II-pictures convey depth and content that realistically change perspective as the viewer changes the viewing position.

    The dissertation concentrates on three restraining factors concerning II-picture progress. Firstly, there is a lack of digital II-pictures available for inter alia comparative research and coding scheme development. Secondly, there is an absence of objective quality metrics that explicitly measure distortion with respect to the II-picture properties: depth and view-angle dependency. Thirdly, low coding efficiencies are achieved when present image coding standards are applied to II-pictures.

    A computer synthesis method has been developed, which enables the production of different II-picture types. An II-camera model forms a basis and is combined with a scene description language that allows for the describing of arbitrary complex virtual scenes. The light transport within the scene and into the II-camera is simulated using ray-tracing and geometrical optics. A number of II-camera models, scene descriptions, and II-pictures are produced using the presented method.

    Two quality evaluation metrics have been constructed to objectively quantify the distortion contained in an II-picture with respect to its specific properties. The first metric models how the distortion is perceived by a viewer watching an II-display from different viewing-angles. The second metric estimates the depth-distribution of the distortion. New aspects of coding-induced artifacts within the II-picture are revealed using the proposed metrics.

    Finally, a coding scheme for II-pictures has been developed that inter alia utilizes the video coding standard H.264/AVC by firstly transforming the II-picture into a pseudo video sequence. The properties of the coding scheme have been studied in detail and compared with other coding schemes using the proposed evaluation metrics. The proposed coding scheme achieves the same quality as JPEG2000 at approximately 1/60th of the storage- or distribution requirements.

  • 38.
    Qureshi, Bilal Hasan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Directional Spectrum Sensing and Transmission Using a Sector Antenna2012Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    Spectrum sensing plays a key role for radio resource awareness in cognitive radio. To enhance the capabilities of cognitive radio nodes, exploiting the spatial resource in addition to frequency and time re-sources seems reasonable. This thesis investigates the possibility of exploiting the spatial resources during sensing and transmission using sector antennas which is also termed as directional spectrum sensing and transmission. The measured radiation patterns from fabricated antenna and radiation patterns obtained from analytical expressions representing circular array of dipole are used for performance analysis. A ray tracer tool is used for modelling the urban environment as well as for wave propagation simulation. The power angular profiles obtained at different locations are further processed in MATLAB using measured and analytical radiation patterns to evaluate the performance in terms of spatial opportunity and detection of weak primary signals. The results show that exploiting the spatial dimension in spectrum sensing using sector antennas increase the opportunities for secondary communication and also improves the detection of primary signals as compared with an omni-directional antenna. Additionally, directional sensing and trans-mission are studied together using analytical radiation patterns. The results show that the service probability as well as range of communica-tion increases with an increase in number of sectors but saturation is achieved when nine sectors are used, indicating that six sectors antenna is the optimum choice for exploring the spatial resource in cognitive radio in a typical multipath urban environment.

  • 39.
    Rizzi, Mattia
    et al.
    University of Brescia, Italy.
    Ferrari, Paolo
    University of Brescia, Italy.
    Flammini, Alessandra
    University of Brescia, Italy.
    Sisinni, Emiliano
    University of Brescia, Italy.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Using LoRa for Industrial Wireless Networks2017In: 2017 IEEE 13th International Workshop on Factory Communication Systems (WFCS), IEEE, 2017, article id 7991972Conference paper (Refereed)
    Abstract [en]

    The new concept of Industry 4.0 has been developed: it includes both Internet of Things (IoT) structure and the local networks that are still needed to carry out real-time tasks. However, forecasts of mass application of consumer IoT system have stimulated the development of new wireless technologies that may also be interesting for industry. In this paper, the LoRa technology is investigated for the implementation of industrial wireless networks suitable for sensors and actuators of the Industry 4.0 era. After a brief overview of LoRa and LoRaWAN, the paper deals with the discussion about using LoRa for industrial applications compared to traditional industrial wireless systems. With only very light modifications to the upper layer of LoRaWAN communication stack, a time slot channel hopping schema is possible. The experimental results show the feasibility of the proposed approach, which is compatible with requirements of soft real-time applications in process industry. In particular, proper time, frequency, and spreading factor planning may allow 6000 nodes accessed up to one minute cycle time.

  • 40.
    Rondón, Raúl
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Landernäs, Krister
    ABB Corporate Research, Sweden.
    Evaluating Bluetooth Low Energy Suitability for Time-Critical Industrial IoT Applications2017In: International Journal of Wireless Information Networks, ISSN 1068-9605, E-ISSN 1572-8129, Vol. 24, no 3, p. 278-290Article in journal (Refereed)
    Abstract [en]

    In recent years, integration of wireless sensornetworks in industrial environments has greatly increased. With this trend, new fields such as industrial IoT have arisen, which in turn have opened the doors to new possibilities that are shaping the future of industrial automation. In contrast to regular wireless networks, however, industrial applications of WSN are characterized for being time-critical systems with highly stringent requirements that challenge all available technologies. Because of its ultra-low energy properties, compatibility with most mobile units, reduced production costs, robustness and hight hroughput, Bluetooth low energy (BLE) is a potential candidate for these settings. This article explores thepotential of BLE of meeting the real-time demands foundin the domain of industrial process automation and industrial IoT. In order to evaluate the suitability of the protocol for these scenarios, the effect of adaptations in the retransmission scheme on the reliability and timeliness performance are thoroughly studied. Three retransmission schemes are evaluated and simulation results proved that by optimally modifying the BLE retransmission model, a maximum delay below 46 ms and a packet loss rate in the order of 105 can be obtained, enabling BLE to fulfill the requirements of even the most demanding cases within the considered range of applications.

  • 41.
    Rondón, Raúl
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Landernäs, Krister
    ABB Corporate Research.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    An Analytical Model of the Effective Delay Performance for Bluetooth Low Energy2016In: IEEE 27th International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC'17), Valencia, Spain, Sept. 2016., IEEE, 2016, p. 6-11, article id 7794553Conference paper (Refereed)
    Abstract [en]

    With the uprising trend of the integration of wireless sensing systems in fields such as health care and industrial processes, where information exchange between power-limited devices is required, lower energy consumption and Quality of Service demands are becoming more stringent. Bluetooth LowEnergy is a promising technology that provides, besides ultra-low energy properties, compatibility with most mobile units. However,apart from power efficiency, opportune and reliable information delivery is mandatory in time-critical applications. In this paper we propose an analytical model of the delay performance of Bluetooth Low Energy for connection-oriented applications under different bit error conditions. In addition to the physical over-the-air latency, we also analyze the effect of the occurrence time of an Application Layer event on the effective transmission delay. We highlight the impact of the device’s processing speed and the timing configuration of the connectionon the final measured latency. Simulation results validate the accuracy of the model for all the analyzed cases.

  • 42.
    Stöggl, Thomas
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. Department of Sport Science and Kinesiology, University of SalzburgHallein/Rif, Austria .
    Holst, Anders
    School of Computer Science and Communication, Royal Institute of Technology, Stockholm, Sweden .
    Jonasson, Arndt
    Swedish Institute of Computer Science, Kista, Sweden.
    Andersson, Erik
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Wunsch, Thomas
    Department of Sport Science and Kinesiology, University of SalzburgHallein/Rif, Austria .
    Norström, Christer
    Swedish Institute of Computer Science, Kista, Sweden .
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. Swedish Olympic Committee, Stockholm, Sweden .
    Automatic classification of the sub-techniques (gears) used in cross-country ski skating employing a mobile phone2014In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 14, no 11, p. 20589-20601Article in journal (Refereed)
    Abstract [en]

    The purpose of the current study was to develop and validate an automatic algorithm for classification of cross-country (XC) ski-skating gears (G) using Smartphone accelerometer data. Eleven XC skiers (seven men, four women) with regional-to-international levels of performance carried out roller skiing trials on a treadmill using fixed gears (G2left, G2right, G3, G4left, G4right) and a 950-m trial using different speeds and inclines, applying gears and sides as they normally would. Gear classification by the Smartphone (on the chest) and based on video recordings were compared. Formachine-learning, a collective database was compared to individual data. The Smartphone application identified the trials with fixed gears correctly in all cases. In the 950-m trial, participants executed 140 ± 22 cycles as assessed by video analysis, with the automatic Smartphone application giving a similar value. Based on collective data, gears were identified correctly 86.0% ± 8.9% of the time, a value that rose to 90.3% ± 4.1% (P < 0.01) with machine learning from individual data. Classification was most often incorrect during transition between gears, especially to or from G3. Identification was most often correct for skiers who made relatively few transitions between gears. The accuracy of the automatic procedure for identifying G2left, G2right, G3, G4left and G4right was 96%, 90%, 81%, 88% and 94%, respectively. The algorithm identified gears correctly 100% of the time when a single gear was used and 90% of the time when different gears were employed during a variable protocol. This algorithm could be improved with respect to identification of transitions between gears or the side employed within a given gear.

  • 43.
    Søgaard, Jacob
    et al.
    Technical University of Denmark.
    Shahid, Muhammad
    BTH.
    Pokhrel, Jeevan
    Montimage, Paris, France.
    Brunnström, Kjell
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems. Acreo Swedish ICT AB.
    On subjective quality assessment of adaptive video streaming via crowdsourcing and laboratory based experiments2017In: Multimedia tools and applications, ISSN 1380-7501, E-ISSN 1573-7721, Vol. 76, no 15, p. 16727-16748Article in journal (Refereed)
    Abstract [en]

    Video streaming services are offered over the Internet and since the service providers do not have full control over the network conditions all the way to the end user, streaming technologies have been developed to maintain the quality of service in these varying network conditions i.e. so called adaptive video streaming. In order to cater for users’ Quality of Experience (QoE) requirements,HTTP based adaptive streaming solutions of video services have become popular.However, the keys to ensure the users a good QoE with this technology is still not completely understood. User QoE feedback is therefore instrumental inimproving this understanding. Controlled laboratory based perceptual quality experiments that involve a panel of human viewers are considered to be the most valid method of the assessment of QoE. Besides laboratory based subjective experiments,crowdsourcing based subjective assessment of video quality is gaining popularity as an alternative method. This article presents insights into a study that investigates perceptual preferences of various adaptive video streaming scenarios through crowdsourcing based and laboratory based subjective assessment.The major novel contribution of this study is the application of Paired Comparison based subjective assessment in a crowdsourcing environmen. The obtained results provide some novel indications, besides confirming the earlier published trends, of perceptual preferences for adaptive scenarios of video streaming. Our study suggests that in a network environment with fluctuations in the bandwidth,a medium or low video bitrate which can be kept constant is the best approach. Moreover, if there are only a few drops in bandwidth, one can choose a medium or high bitrate with a single or few buffering events.

  • 44.
    Tavakoli, Samira
    et al.
    Universidad Politécnicade Madrid, Spain.
    Brunnström, Kjell
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems. Acreo Swedish ICT AB, Sweden.
    Gutiérrez, Jesús
    Universidad Politécnicade Madrid, Spain.
    Quality of Experience of adaptive video streaming: Investigation in service parameters and subjective quality assessment methodology2015In: Signal processing. Image communication, ISSN 0923-5965, E-ISSN 1879-2677, Vol. 39, p. 432-443Article in journal (Refereed)
    Abstract [en]

    The usage of HTTP adaptive streaming (HAS) has become widely spread in multimedia services. Because it allows the service providers to improve the network resource utilization and user's Quality of Experience (QoE). Using this technology, the video playback interruption is reduced since the network and server status in addition to capability of user device, all are taken into account by HAS client to adapt the quality to the current condition. Adaptation can be done using different strategies. In order to provide optimal QoE, the perceptual impact of adaptation strategies from point of view of the user should be studied. However, the time-varying video quality due to the adaptation which usually takes place in a long interval introduces a new type of impairment making the subjective evaluation of adaptive streaming system challenging. The contribution of this paper is two-fold: first, it investigates the testing methodology to evaluate HAS QoE by comparing the subjective experimental outcomes obtained from ACR standardized method and a semi-continuous method developed to evaluate the long sequences. In addition, influence of using audiovisual stimuli to evaluate the video-related impairment is inquired. Second, impact of some of the adaptation technical factors including the quality switching amplitude and chunk size in combination with high range of commercial content type is investigated. The results of this study provide a good insight toward achieving appropriate testing method to evaluate HAS QoE, in addition to designing switching strategies with optimal visual quality.

  • 45.
    Tavakoli, Samira
    et al.
    Universidad Politécnicade Madrid, Spain.
    Egger, S.
    Austrian Institute of Technology, Vienna, Austria.
    Seufert, M.
    University of Würzburg, Würzburg, Germany.
    Schatz, R.
    Austrian Institute of Technology, Vienna, Austria.
    Brunnström, Kjell
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology. Acreo Swedish ICT AB.
    Garcia, N.
    Universidad Politécnica de Madrid, Madrid, Spain.
    Perceptual Quality of HTTP Adaptive Streaming Strategies: Cross-Experimental Analysis of Multi-Laboratory and Crowdsourced Subjective Studies2016In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 34, no 8, p. 2141-2153, article id 7485884Article in journal (Refereed)
    Abstract [en]

    Today's packet-switched networks are subject to bandwidth fluctuations that cause degradation of the user experience of multimedia services. In order to cope with this problem, HTTP adaptive streaming (HAS) has been proposed in recent years as a video delivery solution for the future Internet and being adopted by an increasing number of streaming services, such as Netflix and Youtube. HAS enables service providers to improve users' quality of experience (QoE) and network resource utilization by adapting the quality of the video stream to the current network conditions. However, the resulting time-varying video quality caused by adaptation introduces a new type of impairment and thus novel QoE research challenges. Despite various recent attempts to investigate these challenges, many fundamental questions regarding HAS perceptual performance are still open. In this paper, the QoE impact of different technical adaptation parameters, including chunk length, switching amplitude, switching frequency, and temporal recency, are investigated. In addition, the influence of content on perceptual quality of these parameters is analyzed. To this end, a large number of adaptation scenarios have been subjectively evaluated in four laboratory experiments and one crowdsourcing study. A statistical analysis of the combined data set reveals results that partly contradict widely held assumptions and provide novel insights in perceptual quality of adapted video sequences, e.g., interaction effects between quality switching direction (up/down) and switching strategy (smooth/abrupt). The large variety of experimental configurations across different studies ensures the consistency and external validity of the presented results that can be utilized for enhancing the perceptual performance of adaptive streaming services.

  • 46.
    Timilsina, M.
    et al.
    Department of Electrical Engineering, Jönköping University, Sweden .
    Xu, Youzhi
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Gidlund, Mikael
    ABB Corporate Research, Sweden .
    Comparison between single mesh network and cell based mesh network2012In: 2012 International Conference on Wireless Communications, Networking and Mobile Computing, WiCOM 2012, IEEE conference proceedings, 2012, p. Art. no. 6478456-Conference paper (Refereed)
    Abstract [en]

    Industrial wireless applications have stringent requirements of safety, data update rate, time delay, reliability, failure tolerance, and security. In this paper, a concept of cellbased mesh networks is proposed, and the performance is evaluated by computer simulations. The results show that the average number of hops from sensor nodes to the backbone routers and the average route cost are significantly reduced with a comparison to a conventional mesh topology in multipath fading environments. It is also shown that the cell-based mesh networks can tolerate failures of links, notes and backbone routers. All those imply that the cell-based mesh networks are suitable for industrial wireless sensor networks with stringent requirements of data update rate, time delay, and reliability and failure tolerance.

  • 47.
    Wang, K.
    et al.
    KTH.
    Gavler, A.
    Acreo Swedish ICT.
    Machuca, M.
    Technische Universitýt Mýnchen.
    Wosinska, L.
    KTH.
    Brunnström, K
    Acreo Swedish ICT AB.
    Chen, J.
    KTH.
    Migration Strategies for FTTx Solutions based on Active Optical Networks2016In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 54, no 2, p. 78-86, article id 7402265Article in journal (Refereed)
    Abstract [en]

    AON, one of the most deployed fiber access solutions in Europe, needs to be upgraded in order to satisfy the ever growing bandwidth demand driven by new applications and services. Meanwhile, network providers want to reduce both capital expenditures and operational expenditures to ensure that there is profit coming from their investments. This article proposes several migration strategies for AON from the data plane, topology, and control plane perspectives, and investigates their impact on the total cost of ownership.

  • 48.
    Wang, Yun
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Jiang, Wenxuan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Statistical Processing of IEEE 802.15.4 Data Collected in Industrial Environment2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Wireless sensor network, which is constitute of autonomous sensors, is used for monitoring physical or environmental conditions like temperature, sound, pressure, and so on. The dispersed sensors or nodes will respectively pass their data through the network to the main location. Currently, several standards are ratified or in developing for wireless sensor network, like Wireless Hart, ISA, 100.11a, WIA-PAA, IEEE 802.15.4, etc. Among the standards, Zigbee is often used in industrial applications that require short-range and low-rate wireless transfer. In the research, all the data is collected under industrial environment using IEEE 802.15.4 compliant physical layer, some packets are interfered only by multi-path fading while others are also interfered by Wi-Fi interference. The goal of the thesis is to find out the dependence between the received power (RSS), correlation value (CORR) and bit error rate (BER) of the received message, and their distribution in situations both when the packet is lost or not. Besides, the performance of bit error rate such as the distribution and the features of burst error length under Wi-Fi interference or not will also be tested. All of them are based on a precise statistical processing. 

  • 49.
    Yu, Kan
    et al.
    Mälardalen University.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Åkerberg, Johan
    ABB Corporate Research, Sweden.
    Björkman, Mats
    Mälardalen University, Sweden.
    Performance Evaluations and Measurements of the REALFLOW Routing Protocol in Wireless Industrial Networks2017In: IEEE Transactions on Industrial Informatics, ISSN 1551-3203, E-ISSN 1941-0050, Vol. 13, no 3, p. 1410-1420, article id 7506102Article in journal (Refereed)
    Abstract [en]

    Industrial wireless sensor and actuator networks (IWSANs) offer significant advantages to industria lautomation. However, high-reliability demands and hard communication deadlines pose challenges to its practical applications. To achieve this goal, flooding is considered as a promising approach due to multipath diversity and simplicity. In this paper, an enhanced version of REALFLOW, a flooding-based routing protocol for IWSANs is presented. Compared to the original REALFLOW, network management and network stability are improved. REALFLOW is compared with four other flooding protocols via simulations. The simulation results show that REALFLOW has better performance in terms of reliability and consecutive transmission errors when considering deadlines. Compared with normal flooding, REALFLOW achieves comparable reliability performance with decreased redundancy. Measurements from a prototype implementation conducted in an industrial manufacturing workshop reveal that high-reliability and low-application failure rates can be achieved, giving more confidence in providing reliable wireless sensing and actuating for industrial automation.

  • 50.
    Åkerberg, Johan
    et al.
    ABB Corporate Research.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Lennvall, Tomas
    ABB Corporate Research.
    Landernäs, Krister
    ABB Corporate Research.
    Björkman, Mats
    Mälardalen University.
    Design Challenges and Objectives in Industrial Wireless Sensor Networks2013In: Industrial Wireless Sensor Networks: Applications, Protocols, Standards, and Products / [ed] V. C. Gungor and G. P. Hancke, CRC Press, 2013Chapter in book (Refereed)
1 - 50 of 50
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