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  • 1.
    Ahmad, Shabir
    et al.
    Jeju National University, Jeju, South Korea.
    Hussain, Ishfaq
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Fayaz, Muhammad
    Jeju National University, Jeju, South Korea.
    Kim, Do-Hyeun
    Jeju National University, Jeju, South Korea.
    A Distributed Approach towards Improved Dissemination Protocol for Smooth Handover in MediaSense IoT Platform2018In: Processes, ISSN 2227-9717, E-ISSN 1099-5862, Vol. 6, no 5, article id 46Article in journal (Refereed)
    Abstract [en]

    Recently, the Internet has been utilized by many applications to convey time-sensitive messages. The persistently expanding Internet coverage and its easy accessibility have offered to ascend to a problem which was once regarded as not essential to contemplate. Nowadays, the Internet has been utilized by many applications to convey time-sensitive messages. Wireless access points have widely been used but these access points have limitations regarding area coverage. So for covering a wider space, various access points need to be introduced. Therefore, when the user moves to some other place, the devices expected to switch between access points. Packet loss amid the handovers is a trivial issue. MediaSense is an Internet of Things distributed architecture enabling the development of the IoT application faster. It deals with this trivial handover issue by utilizing a protocol called Distributed Context eXchange Protocol. However, this protocol is centralized in nature and also suffers in a scenario when both sender and receiver address change simultaneously. This paper presents a mechanism to deal with this scenario and presents a distributed solution to deal with this issue within the MediaSense platform. The proposed protocol improves dissemination using retransmission mechanism to diminish packet loss. The proposed protocol has been delineated with a proof of concept chat application and the outcomes have indicated a significant improvement in terms of packet loss.

  • 2.
    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.
    LPED: Channel Diagnostics in WSN Through Channel Coding and Symbol Error Statistics2014In: IEEE ISSNIP 2014 - 2014 IEEE 9th International Conference on Intelligent Sensors, Sensor Networks and Information Processing, Conference Proceedings, Singapore: IEEE Sensors Council, 2014, p. 1-6Conference paper (Refereed)
    Abstract [en]

    Three major obstacles to wireless communication are electromagnetic interference, multipath fading and signal attenuation. The former stems mainly from collocated wireless systems operating in the same frequency band, while the latter two originate from physical properties of the environment. Identifying the source of packet corruption and loss is crucial, since the adequate countermeasures for different types of threats are essentially different. This problem is especially pronounced in industrial monitoring and control applications, where IEEE 802.15.4 communication is expected to deliver data within tight deadlines, with minimal packet loss. This work presents the Lightweight Packet Error Discriminator (LPED) that distinguishes between errors caused by multipath fading and attenuation, and those inflicted by IEEE 802.11 interference. LPED uses Forward Error Correction to determine the symbol error positions inside erroneously received packets and calculates the error density, which is then fed to a discriminator for error source classification. The statistical constituents of LPED are obtained from an extensive measurement campaign in two different types of industrial environments. The classifier incurs no overhead and in ≥90% of cases a single packet is sufficient for a correct channel diagnosis. Experiments show that LPED accelerates link diagnostics by at least 190%, compared to the relevant state-of-the-art approaches.

  • 3.
    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. ABB Corp Res, S-72178 Vasteras, Sweden.
    Zhang, Tingting
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Scrutinizing Bit- and Symbol-Errors of IEEE 802.15.4 Communication in Industrial Environments2014In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 63, no 7, p. 1783-1794Article in journal (Refereed)
    Abstract [en]

    The knowledge of error nature in wireless channels is an essential constituent of efficient communication protocol design. To this end, this paper is the first comprehensive bit- and symbol-level analysis of IEEE 802.15.4 transmission errors in industrial environments. The intention with this paper is to extract the error properties relevant for future improvements of wireless communication reliability and coexistence of radio systems in these harsh conditions. An extensive set of bit-error traces was collected in a variety of scenarios and industrial environments, showing that error behavior is highly dependent on the cause of packet corruption. It is shown that errors inflicted by multipath fading and attenuation exhibit different properties than those imposed by IEEE 802.11 interference. The statistical behavior of these two patterns is concurrently investigated in terms of differences in bit-error distribution, error burst length, channel memory length, and the scale of packet corruption. With these conclusions at hand, abiding to the computational constraints of embedded sensors and the statistical properties of bit-errors, a Reed-Solomon $(15,k)$ block code is chosen to investigate the implications of bit-error nature on practical aspects of channel coding and interleaving. This paper is concluded by a number of findings of high practical relevance, concerning the optimal type, depth, and meaningfulness of interleaving.

  • 4.
    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)
  • 5. Barkowsky, M
    et al.
    Brunnström, Kjell
    Acreo ICT Swedish AB.
    Ebrahimi, T
    Karam, L
    Lebreton, P
    Le Callet, P
    Perkis, A
    Raake, A
    Subedar, M
    Wang, Kun
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Xing, L
    You, J
    Subjective and Objective Visual Quality Assessment in the Context of stereoscopic 3DTV2013In: 3DTV System with Depth-Image-Based Rendering / [ed] Yu, L., Tanimoto, M., and Zhu, C., Springer, 2013, p. 413-437Chapter in book (Refereed)
    Abstract [en]

    Subjective and objective visual quality assessment in the context of stereoscopic three-dimensional TV (3D-TV) is still in the nascent stage and needs to consider the effect of the added depth dimension. As a matter of fact, quality assessment of 3D-TV cannot be considered as a trivial extension of two-dimensional (2D) cases. Furthermore, it may also introduce negative effects not experienced in 2D, e.g., discomfort or nausea. Based on efforts initiated within the cost action ICT 1003 QUALINET, this chapter discusses current challenges in relation to subjective and objective visual quality assessment for stereo-based 3D-TV. Two case studies are presented to illustrate the current state of the art and some of the remaining challenges. © Springer Science+Business Media New York 2013. All rights are reserved.

  • 6.
    Barkowsky, M
    et al.
    University of Nantes, France.
    Masala, E
    Politecnico di Torino, Italy.
    Van Wallendael, G
    Ghent University - iMinds, Belgium.
    Brunnström, Kjell
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems. Acreo Swedish ICT AB, Sweden .
    Staelens, N
    Ghent University - iMinds, Belgium.
    Le Callet, P
    University of Nantes, France.
    Objective Video Quality Assessment - Towards large scale video database enhanced model development.2015In: IEICE transactions on communications, ISSN 0916-8516, E-ISSN 1745-1345, Vol. E98-B, no 1, p. 2-11Article in journal (Refereed)
    Abstract [en]

    The current development of video quality assessment algorithms suffers from the lack of available video sequences for training, verification and validation to determine and enhance the algorithm's application scope. The Joint Effort Group of the Video Quality Experts Group (VQEG-JEG) is currently driving efforts towards the creation of large scale, reproducible, and easy to use databases. These databases will contain bitstreams of recent video encoders (H.264, H.265), packet loss impairment patterns and impaired bitstreams, pre-parsed bitstream information into files in XML syntax, and well-known objective video quality measurement outputs. The database is continuously updated and enlarged using reproducible processing chains. Currently, more than 70,000 sequences are available for statistical analysis of video quality measurement algorithms. New research questions are posed as the database is designed to verify and validate models on a very large scale, testing and validating various scopes of applications, while subjective assessment has to be limited to a comparably small subset of the database. Special focus is given on the principles guiding the database development, and some results are given to illustrate the practical usefulness of such a database with respect to the detailed new research questions.

  • 7.
    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.
    Modelling of EnergyConsumption in IEEE 802.11.ah Networks for M2M Traffic2016In: Proceedings of SNCNW 2016: The 12th Swedish National Computer Networking Workshop, 2016, p. 38-41Conference paper (Refereed)
    Abstract [en]

    IEEE 802.11ah is a sub-1 GHz standard designed to meet the requirements of future machine-to-machine (M2M) communications. The standard should be able to support use cases for the M2M communications with thousands of stations capable of generating both periodic and aperiodic traffic for a single access point. In some cases, like environmental and agricultural monitoring. the nodes are typically powered by battery or through energy harvesting. For this application it is important for the communication to be energy efficient. IEEE 802.11ah introduces new energy saving mechanisms and a novel channel access mechanism to achieve this objective even for networks with a large nodes number. This work proposes a mathematical model to compute the energy consumption of an IEEE 802.11ah network.

  • 8.
    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%.

  • 9. Brotherton, M.D
    et al.
    Huynh-Thu, Q
    Hands, D
    Brunnström, Kjell
    Subjective Multimedia Quality Assessment.2006In: IEICE Transactions on Fundamentals of Electronics Communications and Computer Sciences, ISSN 0916-8508, E-ISSN 1745-1337, Vol. E89-A, no 11, p. 2920-2932Article in journal (Refereed)
  • 10.
    Brunnström, K
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    3D user experience and display performance2013In: Proceedings, 2013Conference paper (Refereed)
  • 11.
    Brunnström, K
    ACREO AB.
    Percieved QoS and Test suites: keynote2008In: ETSI Workshop on Effects of transmission Performance on Multimedia QoS, Prague, 2008Conference paper (Refereed)
  • 12.
    Brunnström, K
    et al.
    Acreo AB, Sweden.
    Hands, D
    BT Innovate, UK.
    Speranza, F
    Communications Research Centre, Canada.
    Webster, A
    NTIA/ITS, United States.
    VQEG Validation and ITU Standardisation of Objective Perceptual Video Quality Metrics2009In: IEEE signal processing magazine (Print), ISSN 1053-5888, E-ISSN 1558-0792, Vol. 26, no 3, p. 96-101Article in journal (Refereed)
    Abstract [en]

    For industry, the need to access accurate and reliable objective video metrics has become more pressing with the advent of new video applications and services such as mobile broadcasting, Internet video, and Internet Protocol television (IPTV). Industry-class objective quality- measurement models have a wide range of uses, including equipment testing (e.g., codec evaluation), transmission- planning and network-dimensioning tasks, head-end quality assurance, in- service network monitoring, and client-based quality measurement. The Video Quality Experts Group (VQEG) is the primary forum for validation testing of objective perceptual quality models. The work of VQEG has resulted in International Telecommunication Union (ITU) standardization of objective quality models designed for standard- definition television and for multimedia applications. This article reviews VQEG's work, paying particular attention to the group's approach to validation testing.

  • 13.
    Brunnström, K
    et al.
    Acreo, Stockholm, Sweden.
    Nordström, L
    Andrén, B
    Visual experience of quality degradation when viewing computer and notebooks displays from an oblique angle2011In: Journal of the Society for Information Display, ISSN 1071-0922, E-ISSN 1938-3657, Vol. 19, no 5, p. 387-397Article in journal (Refereed)
    Abstract [en]

    This study focused on evaluating the user experience of the viewing-angle-dependent quality of computer and notebook displays. The tests were performed in a test lab using a notebook with a prismatic display and a computer monitor with a conventional LCD. The notebook display was tilted and turned during an image-quality test and tilted during an acuity test. On the computer monitor, the turn and tilt was simulated in the image-quality test, for checking the TCO requirements. The results from the image-quality test show that the parameter used in the TCO requirement, luminance ratio, would be a reasonable predictor of image quality. However, the experiment with the notebook display shows that, in general, this is not the case, especially for larger viewing angles where the physical characteristics do not show a gradual variation in luminance. Therefore, the luminance ratio in TCO requirements shall be used with caution. In addition, the results for the notebook display show that the visual acu ity decreased faster with increasing viewing angle than predicted from the luminance decrease alone. This means that it will be harder to resolve small details and will, therefore, have a negative influence on the visual ergonomics.

  • 14.
    Brunnström, K
    et al.
    Acreo AB, Stockholm, Sweden.
    Schenkman, B
    Jacobsen, B
    Object Detection in Cluttered Infrared Images.2003In: Optical Engineering: The Journal of SPIE, ISSN 0091-3286, E-ISSN 1560-2303, Vol. 42, no 2, p. 388-399Article in journal (Refereed)
    Abstract [en]

    Implementation of the Johnson criteria for infrared images is the probabilities of a discrimination technique. The inputs to the model are the size of the target, the range to it, and the temperature difference against the background. The temperature difference is calculated without taking the background structure into consideration, but it may have a strong influence on the visibility of the target. We investigated whether a perceptually based temperature difference should be used as input. Four different models are discussed: 1. a probability of discrimination model largely based on the Johnson criteria for infrared images, 2. a peak signal-to-noise ratio model, 3. a signal-to-clutter ratio model, and 4. two versions of an image discrimination model based on how human vision analyzes spatial information. The models differ as to how much they try to simulate human perception. To test the models, a psychophysical experiment was carried out with ten test persons, measuring contrast threshold detection in five different infrared backgrounds using a method based on a two-alternative forced-choice methodology. Predictions of thresholds in contrast energy were calculated for the different models and compared to the empirical values. Thresholds depend on the background, and these can be predicted well by the image discrimination models, and better than the other models. Future extensions are discussed.

  • 15.
    Brunnström, K
    et al.
    Acreo AB, Stockholm, Sweden.
    Schenkman, B.N
    Acreo AB, Stockholm, Sweden.
    Comparison of the predictions of a spatio-temporal model with the detection of distortion in small moving images2002In: Optical Engineering: The Journal of SPIE, ISSN 0091-3286, E-ISSN 1560-2303, Vol. 41, no 3, p. 711-722Article in journal (Refereed)
  • 16.
    Brunnström, K
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems. Acreo Swedish ICT AB.
    Wang, K
    Acreo Swedish ICT AB.
    Andrén, B
    Acreo Swedish ICT AB.
    Simulator sickness analysis of 3D video viewing on passive 3DTV2013In: Stereoscopic Displays and Applications XXIV / [ed] Woods, A. J., Holliman, N. S., and Favalora, G. E., Bellingham, WA, USA: SPIE - International Society for Optical Engineering, 2013, p. 864802-Conference paper (Refereed)
  • 17.
    Brunnström, Kjell
    et al.
    Kungliga tekniska högskolan.
    Eklund, Jan-Olof
    Kungliga tekniska högskolan.
    Uhlin, Tomas
    Kungliga tekniska högskolan.
    Active fixation for scene exploration1996In: International Journal of Computer Vision, ISSN 0920-5691, E-ISSN 1573-1405, Vol. 17, no 2, p. 137-162Article in journal (Refereed)
    Abstract [en]

    It is well-known that active selection of fixation points in humans is highly context and task dependent. It is therefore likely that successful computational processes for fixation in active vision should be so too. We are considering active fixation in the context of recognition of man-made objects characterized by their shapes. In this situation the qualitative shape and type of observed junctions play an important role. The fixations are driven by a grouping strategy, which forms sets of connected junctions separated from the surrounding at depth discontinuities. We have furthermore developed a methodology for rapid active detection and classification of junctions by selection of fixation points. The approach is based on direct computations from image data and allows integration of stereo and accommodation cues with luminance information. This work form a part of an effort to perform active recognition of generic objects, in the spirit of Malik and Biederman, but on real imagery rather than on line-drawings.

  • 18.
    Brunnström, Kjell
    et al.
    Kungliga tekniska högskolan.
    Eklundh, Jan-Olof
    Kungliga tekniska högskolan.
    Lindeberg, Tony
    Kungliga tekniska högskolan.
    On scale and resolution in active analysis of local image structure1990In: Image and Vision Computing, ISSN 0262-8856, E-ISSN 1872-8138, Vol. 8, no 4, p. 289-296Article in journal (Refereed)
    Abstract [en]

    Focus-of-attention is extremely important in human visual perception. If computer vision systems are to perform tasks in a complex, dynamic world they will have to be able to control processing in a way that is analogous to visual attention in humans. Problems connected to foveation (examination of selected regions of the world at high resolution) are examined. In particular, the problem of finding and classifying junctions from this aspect is considered. It is shown that foveation as simulated by controlled, active zooming in conjunction with scale-space techniques allows for robust detection and classification of junctions.

  • 19.
    Brunnström, Kjell
    et al.
    Acreo.
    Josefsson, Katarina
    Acreo.
    Andrén, Börje
    Acreo.
    The effects of glossy screens on the visual ergonomics of flat panel displays.2008In: Journal of the Society for Information Display, ISSN 1071-0922, E-ISSN 1938-3657, Vol. 16, no 10, p. 1041-1049Article in journal (Refereed)
    Abstract [en]

    The TCO requirements provide well-known and recognized quality labels for displays.For these requirements to remain useful, they must continuously be reviewed and updated when nec-essary. The study described here was performed in response to the market trend of designing flat-paneldisplays and notebooks with glare panels. The purpose of this study was to investigate subjectiveresponses to display screens of different gloss levels for office workers working on different tasks undernormal office-lighting conditions. The study consisted of three parts, one where the users should setan acceptable reflex level, one where the user should rate their disturbance on a category scale, andone where the visual acuity of the users were investigated whether they were affected by glare or not.The results show that increasing gloss and increasing luminance levels had negative effects on theacceptance and the disturbance of reflexes. There were statistically significant differences in theacceptance and the disturbance levels between screens with low gloss and screens with high gloss,which suggests that screens with the highest gloss levels should be avoided. The study did not showan effect on the performance based on acuity testing.

  • 20.
    Brunnström, Kjell
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems. Acreo Swedish ICT AB, Kista, Sweden.
    Wang, Kun
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems. Acreo Swedish ICT AB, Kista, Sweden.
    Andrén, Börje
    Acreo Swedish ICT AB, Kista, Sweden.
    Kulyk, Valentin
    Ericsson Research, Sweden.
    Tavakoli, Samira
    Universidad Politécnica de Madrid, Spain.
    Hedberg, Christer
    Acreo Swedish ICT AB, Kista, Sweden.
    Ananth, Indirajith Vijai
    Acreo Swedish ICT AB, Kista, Sweden.
    Hussein, Mahir
    Acreo Swedish ICT AB, Kista, Sweden.
    Folkesson, Mats
    Ericsson Research, Sweden.
    Barkowsky, Marcus
    Acreo Swedish ICT AB, Kista, Sweden.
    3D Video Quality of Experience - Influence of Scale and Crosstalk Invited2014In: Proceedings of the 8th International Workshop on Video Processing and Quality Metrics for Consumer Electronics VPQM-2014, Scottsdale, AZ, USA, 2014Conference paper (Refereed)
    Abstract [en]

    This paper gives an overview of three recent studies by the authors on the topic of 3D video Quality of Experience (QoE). Two of studies [1,2] investigated different psychological dimension that may be needed for describing 3D video QoE and the third the visibility and annoyance of crosstalk[3]. The results shows that the video quality scale could be sufficient for evaluating S3D video experience for coding and spatial resolution reduction distortions. It was also confirmed that with a more complex mixture of degradations more than one scale should be used to capture the QoE in these cases. The study found a linear relationship between the perceived crosstalk and the amount of crosstalk.

  • 21.
    Brunnström, Kjell
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems. Acreo Swedish ICT AB.
    Wang, Kun
    Acreo Swedish ICT AB.
    Tavakoli, Samira
    Universidad Politécnica de Madrid, Spain.
    Andrén, Börje
    Acreo Swedish ICT AB.
    Symptoms analysis of 3D TV viewing based on Simulator Sickness Questionnaires2017In: Quality and User Experience, ISSN 2366-0147, Vol. 2, no 1Article in journal (Refereed)
    Abstract [en]

    Stereoscopic 3D TV viewing puts different visual demands on the viewer compared to 2D TV viewing. Previous research has reported on viewers' fatigue and discomfort and other negative effects. This study is to investigate further how severe and what symptoms may arise from somewhat longish 3D TV viewing.

    The MPEG 3DV project is working on the next-generation video encoding standard and in this process, MPEG issued a call for proposal of encoding algorithms. To evaluate these algorithms a large scale subjective test was performed involving Laboratories all over the world[1, 2]. For the participating Labs, it was optional to administer a slightly modified Simulator Sickness Questionnaire (SSQ) before and after the test. One of the SSQ data sets described in this article is coming from this study. The SSQ data from the MPEG test is the largest data set in this study and also contains the longest viewing times. Along with the SSQ data from the MPEG test, we have also collected questionnaire data in three other 3D TV studies. We did two on the same 3D TV (passive film pattern retarder) as in the MPEG test, and one was using a projector system. As comparison SSQ data from a 2D video quality experiment is also presented. 

    This investigation shows a statistically significant increase in symptoms after viewing 3D TV primarily related to the visual or Oculomotor system. Surprisingly, 3D video viewing using projectors did not show this effect.

  • 22.
    Butun, Ismail
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Pereira, Nuno
    Polytechnic Institute of Porto, Porto, Portugal .
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Analysis of LoRaWAN V1.1 Security2018In: Proceedings of the 4th ACM MobiHoc Workshop on Experiences with the Design and Implementation of Smart Objects (SMARTOBJECTS '18)., ACM Digital Library, 2018Conference paper (Refereed)
    Abstract [en]

    LoRa and the LoRaWAN specification is a technology for Low Power Wide Area Networks (LPWAN) designed to allow connectivity for connected objects, such as remote sensors. Several previous works revealed various weaknesses regarding the security of LoRaWAN v1.0 (the official 1st draft) and these led to improvements included in LoRaWAN v1.1, released on Oct 11, 2017. In this work, we provide the first look into the security of LoRaWAN v1.1. We present an overview of the protocol and, importantly, present several threats to this new version of the protocol. Besides, we propose our own ramification strategies for the mentioned threats, to be used in developing next version of LoRaWAN. The threats presented were not previously discussed, they are possible even within the security assumptions of the specification and are relevant for practitioners implementing LoRa-based applications as well researchers and the future evolution of the LoRaWAN specification.

  • 23.
    Dadash Pour Khalkhali, Mohammad Mehdi
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    User Experience Enhancement in 3D Video Conferencing2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    3D video conferencing is continuously evolving to make the visual experience realistic. The main advantage of 3D video conferencing deals with the addition of depth perception which enhances the user experience. The configuration of capturing and rendering equipments and the location of scene objects play an essential role in the quality of the user experience. An incorrect configuration of equipment parameters or an inconsistent distribution of scene components could cause an uncomfortable user experience, yielding in user sickness and dizziness.

    The aim of this thesis is therefore to provide the tools and methods to assure a comfortable user experience when using Ericsson’s stereoscopic 3D video conferencing system. To achieve this goal, an investigation on the capturing and rendering systems has been performed to identify possible conflicts. This investigation has shown that accommodation-convergence rivalry, comfortable viewing range and stereo framing violation are the major sources of user discomfort in 3D video conferencing.

    An algorithm for continuous analysis of produced stereoscopic content has been proposed. In particular, it detects wrong equipment configuration and problematic content in real time by means of automatic adjustments or user interaction, either at initiation phase or during the call session at capturing side. To validate and evaluate the efficiency of the implemented solution, a subjective test with participation of the 3D experts has been carried out. It has been shown that the proposed solution can detect targeted problems with high accuracy and apply corrective actions. It is important to note that manual solutions are not immune to problems. Nevertheless, it has also been shown that automatic solutions can considerably compensate manual methods inconsistency and provide a comfortable user experience. 

  • 24.
    De Moor, K
    et al.
    NTNU, Trondheim, Norway.
    Andrén, B
    Acreo Swedish ICTAB, Kista, Sweden.
    Yi, G
    Acreo Swedish ICTAB, Kista, Sweden.
    Brunnström, Kjell
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems. Acreo Swedish ICTAB, Kista, Sweden.
    Wang, K
    Acreo Swedish ICTAB, Kista, Sweden.
    Drott, A
    Volvo Cars AB, Gothenburg, Sweden.
    Hermann, D
    Volvo Cars AB, Gothenburg, Sweden.
    Influence of high ambient illuminance and display luminance on readability and subjective preference2015In: Proceedings of SPIE - The International Society for Optical Engineering / [ed] Rogowitz, B., Pappas, T. N., and de Ridder, H., Bellingham, WA, USA: SPIE - International Society for Optical Engineering, 2015, Vol. 9394, p. Art. no. 93941E-Conference paper (Refereed)
    Abstract [en]

    Many devices, such as tablets, smartphones, notebooks, fixed and portable navigation systems are used on a (nearly) daily basis, both in in- and outdoor environments. It is often argued that contextual factors, such as the ambient illuminance in relation to characteristics of the display (e.g., surface treatment, screen reflectance, display luminance...) may have a strong influence on the use of such devices and corresponding user experiences. However, the current understanding of these influence factors is still rather limited. In this work, we therefore focus in particular on the impact of lighting and display luminance on readability, visual performance, subjective experience and preference. A controlled lab study (N=18) with a within-subjects design was performed to evaluate two car displays (one glossy and one matte display) in conditions that simulate bright outdoor lighting conditions. Four ambient luminance levels and three display luminance settings were combined into 7 experimental conditions. More concretely, we investigated for each display: (1) whether and how readability and visual performance varied with the different combinations of ambient luminance and display luminance and (2) whether and how they influenced the subjective experience (through self-reported valence, annoyance, visual fatigue) and preference. The results indicate a limited, yet negative influence of increased ambient luminance and reduced contrast on visual performance and readability for both displays. Similarly, we found that the self-reported valence decreases and annoyance and visual fatigue increase as the contrast ratio decreases and ambient luminance increases. Overall, the impact is clearer for the matte display than for the glossy display.

  • 25.
    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.

  • 26.
    Eriksson, Magnus
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Mahmud, Arif
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Transmitter Macrodiversity in Multihopping: SFN based algorithm for improved node reachability and robust routing2010In: World Academy of Science, Engineering and Technology (WASET) International Conference on Computer Science and Technology (ICCST’10), Rome, Italy, 28-30 April 2010, Rome, Italy, 2010, p. 404-408Conference paper (Refereed)
    Abstract [en]

    A novel idea presented in this paper is to combine multihop routing with single-frequency networks (SFNs) for a broadcasting scenario. An SFN is a set of multiple nodes that transmit the same data simultaneously, resulting in transmitter macrodiversity. Two of the most important performance factors of multihop networks, node reachability and routing robustness, are analyzed. Simulation results show that our proposed SFN-D routing algorithm improves the node reachability by 37 percentage points as compared to non-SFN multihop routing. It shows a diversity gain of 3.7 dB, meaning that 3.7 dB lower transmission powers are required for the same reachability. Even better results are possible for larger networks. If an important node becomes inactive, this algorithm can find new routes that a non-SFN scheme would not be able to find. Thus, two of the major problems in multihopping are addressed; achieving robust routing as well as improving node reachability or reducing transmission power.

  • 27.
    Eriksson, Magnus
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Rahman, S. M. Hasibur
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Fraile, Francisco
    Universitat Politècnica de València, Spain .
    Sjöström, Mårten
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Efficient Interactive Multicast over DVB-T2: Utilizing Dynamic SFNs and PARPS2013In: IEEE International Symposium on Broadband Multimedia Systems and Broadcasting, BMSB, IEEE conference proceedings, 2013, p. Art. no. 6621700-Conference paper (Refereed)
    Abstract [en]

    In the terrestrial digital TV systems DVB-T/H/T2, broadcasting is employed, meaning that all TV programs are sent over all transmitters, also where there are no viewers. This is inefficient utilization of spectrum and transmitter equipment. Applying interactive multicasting over DVB-T2 is a novel approach that would substantially reduce the spectrum required to deliver a certain amount of TV programs. Further gain would be achieved by Dynamic single-frequency network (DSFN) formations, which can be implemented using the concept of PARPS (Packet and Resource Plan Scheduling). A Zipf-law heterogeneous program selection model is suggested. For a system of four coordinated transmitters, and certain assumptions, IP multicasting over non-continuous transmission DSFN gives 1740% increase in multiuser system spectral efficiency (MSSE) in (users∙bit/s)/Hz/site as compared to broadcasting over SFN.

  • 28.
    Farag, Hossam
    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.
    Österberg, Patrik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    PR-CCA MAC: A Prioritized Random CCA MAC Protocol for Mission-Critical IoT Applications2018In: IEEE International Conference on Communications (ICC'18), Kansas, USA, May 2018., 2018Conference paper (Refereed)
    Abstract [en]

    A fundamental challenge in Mission-Critical Internetof Things (MC-IoT) is to provide reliable and timely deliveryof the unpredictable critical traffic. In this paper, we propose an efficient prioritized Medium Access Control (MAC) protocol for Wireless Sensor Networks (WSNs) in MC-IoT control applications. The proposed protocol utilizes a random Clear Channel Assessment (CCA)-based channel access mechanism to handlethe simultaneous transmissions of critical data and to reduce thecollision probability between the contending nodes, which in turn decreases the transmission latency. We develop a Discrete-Time Markov Chain (DTMC) model to evaluate the performance of the proposed protocol analytically in terms of the expected delay and throughput. The obtained results show that the proposed protocolcan enhance the performance of the WirelessHART standard by 80% and 190% in terms of latency and throughput, respectively along with better transmission reliability.

  • 29.
    Farag, Hossam
    et al.
    Aswan University, Egypt.
    Mohamed, Ehab
    Osaka University, Japan.
    An Efficient Dynamic Thresholds Energy Detection Technique for Cognitive Radio Spectrum Sensing2014In: 10th International Computer Engineering Conference: Today Information Society What's Next?, ICENCO 2014, IEEE, 2014, p. 1623-1628Conference paper (Refereed)
    Abstract [en]

    Cognitive Radio (CR) is an intelligent technique for opportunistic access of idle resources. In CR, Spectrum sensing is one of its important key functionalities. It is used to sense the unused spectrumin an opportunistic manner. Energy detection constitutes a preferred approach for spectrum sensing in cognitive radio due to its simplicity and applicability. The conventional energy detection technique, which is based upon fixed threshold, is sensitive to noise uncertainty which is unavoidable in practical cases. This noise uncertainty gets the fixed threshold energy detector un-optimized in its performance. In this paper, an efficient energy detector is proposed for optimal CR performance. The proposed scheme is based upon a dynamic threshold energy detection algorithm, in which, the decision threshold is toggled between two levels based upon the average energy received from the primary user (PU) during a specified period of observation. Thresholds evaluations are based upon estimating the noise uncertainty factor. These thresholds are used to maximize the probability of detection (Pd) and minimize the probability of false alarm (Pfa). Theoretical analysis and simulation results show the effectiveness of the proposed scheme in comparison to the conventional energy detection method with less increase in complexity.

  • 30.
    Farag, Hossam
    et al.
    Aswan University, Egypt.
    Mohamed, Ehab M.
    Aswan University, Egypt.
    Dynamic Threshold Hard Decision Cooperative Spectrum Sensing Using Two-Stage Censoring2016In: 23rd International Conference on Telecommunications, ICT 2016, IEEE, 2016, p. 38-42Conference paper (Refereed)
    Abstract [en]

    In hard decision cooperative spectrum sensing (CSS), each secondary user (SU) or simply cognitive radio user (CR) senses the primary user (PU) activity via a Sensing channel (S-channel) and forwards its own binary decision to a fusion center (FC) via a Reporting channel (R-channel) to make a final decision regarding PU existence. In practical scenarios, both S-channels and R-channels are contaminated with noise, fading and shadowing effects. Thus, the FC may receive faulty decisions from the CRs, which in turn degrades the overall sensing performance of the cognitive radio networks (CRNs). In this paper, an efficient hard decision CSS with two-stage censoring is proposed for boosting the sensing performance of CRNs against noise uncertainty inherent in the S-channels and erroneous inherent in the R-channels. In the first stage, CRs with low quality R-channels are censored by the FC, hence only CRs with high quality R-channels are selected for the next stage of censoring. In the second stage, the low confident CRs with high noise uncertainty factors of their S-channels are censored by the FC, i.e., the FC selects the candidate CRs with the highest quality R-channels and the lowest noisy S-channels. For boosting the sensing decisions made by the CRs, a double dynamic threshold (DDT) is utilized by each CR based on an estimated value of the noise uncertainty factor of its S-channel. The new detection and false alarm probabilities are evaluated mathematically for the proposed scheme. Moreover, numerical analysis is used to confirm the high potency of the proposed scheme over some existing hard decision CSS schemes.

  • 31.
    Farag, Hossam
    et al.
    Aswan University, Egypt.
    Mohamed, Ehab M.
    Osaka University, Japan.
    Hard Decision Cooperative Spectrum Sensing Based on Estimating the Noise Uncertainty Factor2015In: Proceedings - 2015 10th International Conference on Computer Engineering and Systems, ICCES 2015, IEEE, 2015, p. 217-222Conference paper (Refereed)
    Abstract [en]

    Spectrum Sensing (SS) comprises the most important component in Cognitive Radio (CR) systems. Cooperative Spectrum Sensing (CSS) is proposed as an effective approach to improve detection performance in fading environments. This paper introduces an efficient energy detection based hard decision CSS algorithm to alleviate the noise uncertainty effect. In the proposed algorithm, the decision threshold is dynamically switched between two levels based on a prior prediction of the Primary User (PU) activity. The two threshold levels are evaluated using an estimated value of the noise uncertainty factor to maximize the probability of detection and minimize the probability of false alarm. The proposed algorithm is studied theoretically to deduce the enhanced detection and false alarm probabilities. Moreover, simulation analysis is used to confirm the theoretical claims and prove the high potency of the proposed scheme compared to the conventional CSS using different fusion rules.

  • 32.
    Farag, Hossam
    et al.
    Aswan University, Egypt.
    Mohamed, Ehab M.
    Osaka University, Japan.
    Improved Cognitive Radio Energy Detection Algorithm Based upon Noise Uncertainty Estimation2014In: National Radio Science Conference, NRSC, Proceedings, IEEE, 2014, p. 107-115Conference paper (Refereed)
    Abstract [en]

    Cognitive Radio (CR) is a regulated technique for opportunistic access of idle resources. In CR, Spectrum sensing is one of its important key functionalities. It is used to sense the unused spectrum in an opportunistic manner. Energy detection constitutes a preferred approach for spectrum sensing in cognitive radio due to its simplicity and applicability. The traditional energy detection technique, which is based upon fixed threshold, is sensitive to noise uncertainty which is unavoidable in practical cases. This noise uncertainty gets the fixed threshold energy detector un-optimized in its performance. In this paper, an efficient energy detector is proposed for optimal CR performance. The proposed scheme is a dynamic threshold energy detection algorithm, in which, two threshold levels are utilized based upon the average energy received from the primary user (PU) during a specified period of observation. Thresholds evaluations are based upon estimating the noise uncertainty factor. These thresholds are used to maximize the probability of detection (Pd) and minimize the probability of false alarm (Pfa). Theoretical analysis and simulation results show the effectiveness of the proposed scheme in comparison to the traditional energy detection method with less increase in complexity.

  • 33.
    Farag, Hossam
    et al.
    Aswan University, Egypt.
    Mohamed, Ehab M.
    Osaka University, Japan.
    Soft Decision Cooperative Spectrum Sensing Based Upon Noise Uncertainty Estimation2015In: 2015 IEEE International Conference on Communication Workshop, ICCW 2015, IEEE, 2015, p. 1623-1628Conference paper (Refereed)
    Abstract [en]

    Spectrum Sensing (SS) constitutes the most critical task in Cognitive Radio ( CR) systems for Primary User (PU) detection. Cooperative Spectrum Sensing (CSS) is introduced to enhance the detection reliability of the PU in fading environments. In this paper, we propose a soft decision based CSS algorithm using energy detection by taking into account the noise uncertainty effect. In the proposed algorithm, two threshold levels are utilized based on predicting the current PU activity, which can be successfully expected using a simple successive averaging process with time. The two threshold levels are evaluated based on estimating the noise uncertainty factor. In addition, they are toggled in a dynamic manner to compensate the noise uncertainty effect and to increase the probability of detection and decrease the probability of false alarm. Theoretical analysis is performed on the proposed algorithm to evaluate its enhanced false alarm and detection probabilities over the conventional soft decision CSS using different combining schemes. In addition, simulation results show the high efficiency of the proposed scheme compared to the conventional soft decision CSS, with high computational complexity enhancements.

  • 34.
    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.

  • 35.
    Forsström, Stefan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Österberg, Patrik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Kanter, Theo
    Department of Computer and System Sciences Stockholm University.
    Evaluating Ubiquitous Sensor Information Sharing on the Internet-of-Things2012In: Proc. of the 11th IEEE Int. Conference on Trust, Security and Privacy in Computing and Communications, TrustCom-2012: 11th IEEE Int. Conference on Ubiquitous Computing and Communications, IUCC-2012, IEEE conference proceedings, 2012, p. 1454-1460Conference paper (Refereed)
    Abstract [en]

    Next generation context-aware mobile applicationswill require a continuous update of relevant information about auser’s surroundings, in order to create low latency notificationsand high quality of experience. Existing mobile devices alreadycontain a large number of built in sensors which are capableof producing huge amounts of sensor data, exceeding boththe capacity of the local storage and the Internet connection.Therefore, we will in this paper study the limits when sharingcontextual information from mobile devices, as well as finding theimpact of this information overload for the Internet-of-Things.Furthermore, we present an evaluation model for assessing theeffort required to present applications with relevant contextinformation. In conclusion, the model shows that one feasiblesolution for the future Internet-of-Things is a peer-to-peer basedsolution which can control the flow of information without anycentralized authority, to circumvent earlier limitations.

  • 36. Fuchs, Harald
    et al.
    Doehla, Stefan
    Jennehag, Ulf
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thoma, Herbert
    Faerber, Nikolaus
    Encoder and method for generating a stream of data2010Patent (Other (popular science, discussion, etc.))
  • 37.
    Gamukama, Elly
    et al.
    Dept. of Computer and Systems Sciences, Stockholm University.
    Larsson, Aron
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems. Dept. of Computer and Systems Sciences, Stockholm University.
    Popov, Oliver
    Dept. of Computer and Systems Sciences, Stockholm University.
    Mugisha, Joseph Y. T.
    Department of Mathematics, College of Natural Sciences, Makerere University, Uganda.
    The Decision Model for the Internet Services in the Context of Development2015In: Procedia Computer Science / [ed] Luiz Flavio Autran Monteiro Gomes, Raul Colcher, Peter Wolcott, Enrique Herrera-Viedma and Yong Shi, Elsevier, 2015, Vol. 55, p. 622-631Conference paper (Refereed)
    Abstract [en]

    The Internet Services in the Context of Development (ISCD) model is structured in four levels of hierarchy based on the Analytical Hierarchy Processes (AHP) theory. The model provides a formal approach of establishing the relative importance of Internet services in the context of fostering national development. This paper presents the fundamental conceptsof themodel. Pairwise Comparisons (PCs) technique the cornerstone of the AHP theory is used as the baseline technique for measuring the intensity of preference between the Internet traffic classes (therein their respective services they deliver to end users) in the process of formulating the judgment matrix. The ISCD model is modelled to process data obtained from a group of individual decision makers that are independent from each other. Hence decision makers are weighted in the process of aggregating their priority vectors and the normalized weighted geometric mean method (NWGMM) is used to compute the group's priority vector, which is the final output of the model.

  • 38.
    Gamukana, Elly Amani
    et al.
    Dept. of Computer and Systems Sciences, Stockholm University.
    Popov, Oliver
    Dept. of Computer and Systems Sciences, Stockholm University.
    Larsson, Aron
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    A Descriptive Model for Aligning the Goals of the Internet Stakeholders in LDCs2014Conference paper (Refereed)
    Abstract [en]

    The Internet as a platform for services provision and delivery is adopted world over. To least developed countries it is further perceived as a medium for fostering development. A perception that is likely not to be easily achieved because the decisions that led to its existence in such countries never addressed the need of aligning the stakeholders’ goals which inherit the misalignments in present Internet architectural model. We present a model based on AHP theory that lays strategies through which informed decisions for aligning stakeholders’ goals can be made to use the Internet as medium for enhancing national development initiatives.

  • 39.
    Garcia, M.-N
    et al.
    Technische Universitat Berlin, Germany.
    de Simone, F
    Télécom ParisTech, France.
    Tavakoli, S
    Universidad Politécnica de Madrid, Spain.
    Staelens, N
    Ghent University/iMinds, Belgium.
    Egger, S
    Austrian Institute of Technology/ Innovation Systems Department/Technology Experience, Austria.
    Brunnström, Kjell
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Raake, A
    Technische Universitat Berlin, Germany.
    Quality of Experience and HTTP adaptive streaming: A review of subjective studies2014In: Vol: Proc. 6th International Workshop on Quality of Multimedia Experience (QoMEX 2014), Singapore, 2014Conference paper (Refereed)
    Abstract [en]

    HTTP adaptive streaming technology has become widely spread in multimedia services because of its ability to provide adaptation to characteristics of various viewing devices and dynamic network conditions. There are various studies targeting the optimization of adaptation strategy. However, in order to provide an optimal viewing experience to the end-user, it is crucial to get knowledge about the Quality of Experience (QoE) of different adaptation schemes. This paper overviews the state of the art concerning subjective evaluation of adaptive streaming QoE and highlights the challenges and open research questions related to QoE assessment.

  • 40.
    Gidlund, Mikael
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Han, Song
    University of Connecticut, USA.
    Sisinni, Emiliano
    University of Brescia, Italy.
    Saifullah, Abusayeed
    Wayne State University, USA.
    Jennehag, Ulf
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Guest Editorial From Industrial Wireless Sensor Networks to Industrial Internet of Things2018In: IEEE Transactions on Industrial Informatics, ISSN 1551-3203, E-ISSN 1941-0050, Vol. 4, no 5, p. 2194-2198Article in journal (Refereed)
  • 41.
    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.

  • 42.
    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

  • 43.
    Guntupalli, Lakshmikanth
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Farag, Hossam
    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.
    Priority-Oriented Packet Transmissions in Internet of Things: Modeling and Delay Analysis2018In: IEEE International Conference on Communications (ICC'18), Kansas, USA, May 2018, 2018Conference paper (Refereed)
    Abstract [en]

    Priority-oriented packet transmission (PPT) has been a promising solution for transmitting time-critical packets in timely manner during emergency scenarios in Internet ofThings (IoT). In this paper, we develop two associated discrete time Markov chain (DTMC) models to analyze performance of the PPT in an IoT network. Using the proposed DTMC models, we investigate the effect of traffic prioritization interms of average packet delay for a synchronous medium access control (MAC) protocol. Furthermore, the results obtained from analytical models are validated via discrete-event simulations. Numerical results prove the accuracy of the models and reveal the behavior of priority based packet transmissions.

  • 44.
    Guntupalli, Lakshmikanth
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Ghose, Debasish
    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 Efficient Consecutive Packet Transmissions in Receiver-initiated Wake-up Radio Enabled WSNs2018In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 18, no 11, p. 4733-4745Article in journal (Refereed)
    Abstract [en]

    In wake-up radio (WuR)-enabled wireless sensor networks, data communication among nodes is triggered in an on-demand manner, by either a sender or a receiver. For receiver-initiated WuR (RI-WuR), a~receiving node wakes up sending nodes through a wake-up call. Correspondingly sending nodes transmit packets in a traditional way by competing with one another multiple times in a single operational cycle. In~this paper, we propose a receiver-initiated consecutive packet transmission WuR (RI-CPT-WuR) medium access control (MAC) protocol, which eliminates multiple competitions to achieve higher energy efficiency. Furthermore, we develop two associated discrete time Markov chains (DTMCs) for evaluating the performance of RI-CPT-WuR and an existing RI-WuR MAC protocol. Using the solutions from the DTMC models, closed-form expressions for network throughput, average delay, packet reliability ratio, energy consumption and lifetime, and energy efficiency for both protocols are obtained. Numerical results demonstrate the superiority of the RI-CPT-WuR protocol.

  • 45.
    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. 

  • 46.
    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.
    Li, Frank Y.
    University of Agder, Norway.
    An On-Demand Energy Requesting Scheme for Wireless Energy Harvesting Powered IoT Networks2018In: IEEE Internet of Things Journal, ISSN 2327-4662Article in journal (Refereed)
    Abstract [en]

    Energy harvesting (EH) delivers a unique technique for replenishing batteries in Internet of Things (IoT) devices. Equipped with an energy harvesting accessory, EH-enabled sensor nodes/IoT devices extract energy from ambient resources such as solar or radio frequency (RF) signals. Relying on residual battery or/and harvested energy, sensor nodes in an IoT network perform data exchange activities. Otherwise, the delivery of sensed data would be delayed until sufficient energy is harvested. In this paper, we propose an on-demand energy requesting (OER) mechanism for improving the delay performance of a wireless EH-powered IoT network. The proposed scheme acquires energy when necessary from an energy transmitter that is capable of transmitting energy via directed RF signals. Furthermore we develop two associated discrete time Markov chain (DTMC) models to analyze the performance of the OER scheme, targeting at a generic synchronous medium access control (MAC) protocol. Using the proposed DTMC models, we evaluate OER with respect to average packet delay, network throughput, packet loss probability, and packet reliability ratio by employing a specific synchronous MAC protocol. Numerical results obtained from both analysis and discrete-event simulations coincide with each other, indicating the accuracy of the models and revealing the behavior of EH based packet transmissions.

  • 47.
    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.

  • 48.
    Hansson, Karin
    et al.
    Institutionen för data- och systemvetenskap, Stockholms universitet.
    Ekenberg, Love
    Institutionen för data- och systemvetenskap, Stockholms universitet.
    Danielson, Mats
    Institutionen för data- och systemvetenskap, Stockholms universitet.
    Larsson, Aron
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Gustafsson Fürst, Johanna
    Liljenberg, Thomas
    Prototyping for Participatory Democracy: Fine Arts as Means for the Study of Multi-modal Communication in Public Decision Making2011In: Interactive Media Arts Conference: The Unheard Avantgarde, 2011Conference paper (Refereed)
    Abstract [en]

    We present a thematic art project in a suburb of Stockholm as a means to generate problem areas in focus for a research project on multimodal communication and democratic decision-making. Through art we play with different techniques and ideas about democracy in a particular location in order to obtain a better understanding of the citizens and their environments. Artists' actions, installations and mediations create a direct confrontation with the place and its inhabitants, and explore the dynamic relationships that constitute its context. The common denominator for the invited artists is that they work with situation-specific emancipatory art that in various ways relates to the physical and mediated public sphere. The art project is a collaborative process where the artists develop the project and take part in the contextualization in collaboration with researchers. This is achieved partly through a shared memory work on the theme of power / powerlessness. From this feminist research practice notions of democracy is examined in order to investigate, expose, enhance and / or remodel relations of the site. The aim with the art project is to put the site and the individual in a web of geographical, social and economic contexts. The aim is also to contribute to a debate on artistic research by showing how art can be viewed as a qualitative method. Through the practice of the memory work method we contribute to the development of this methodology, and map out a space for art in the field of science.

  • 49.
    Hansson, Karin
    et al.
    Dept. of Computer and Systems Sciences, Stockholm University.
    Karlström, Petter
    Dept. of Computer and Systems Sciences, Stockholm University.
    Larsson, Aron
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Verhagen, Harko
    Dept. of Computer and Systems Sciences, Stockholm University.
    Actory: A Tool for Visualizing Reputation as a Meansto Formalize Informal Social Behavior2011In: Proceedings of the 2011 International Conference on Reputation, 2011Conference paper (Refereed)
    Abstract [en]

    In order to investigate and challenge a normative liberal democraticview of participation, we propose an experimental system based on differencesin reputation and user activity. Based on democratic meeting techniques andsocial media, basic principles for a groupware are formulated containing typicaldemocratic features such as voting and discussion, but taking reputation intoaccount and clarifying the individual's activities in relation to the group. Theprototype stands in contrast to commonly used internet forums by highlightingdifferences in reputation and activity and making these visible and changeableby its users thus shedding some light on status and reputation issues in internetforums and groupware.

  • 50.
    Hansson, Karin
    et al.
    Dept. of Computer and Systems Sciences, Stockholm University.
    Karlström, Petter
    Dept. of Computer and Systems Sciences, Stockholm University.
    Larsson, Aron
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Verhagen, Harko
    Dept. of Computer and Systems Sciences, Stockholm University.
    Reputation, inequality and meeting techniques: Visualising user hierarchy to support collaboration2014In: Computational and mathematical organization theory, ISSN 1381-298X, E-ISSN 1572-9346, Vol. 20, no 2, p. 155-175Article in journal (Refereed)
    Abstract [en]

    Equality within groups is ordinarily taken for granted when technology for e-democracy is conceived and developed. However, inequality in online communication is just as common as in other social contexts. Therefore, we have developed a groupware with the express purpose of illuminating imbalance of power. Inequalities are measured and made visible to users of the system, and they change dynamically as actions are taken by users. The system is based on democratic meeting techniques and is reminiscent of a strategy game based on social media. Each participant’s score within the game is dynamically calculated and reflects that user’s activity, others’ reactions to that activity and reactions to others’ activities. The calculations and weighing mechanisms are open to inspection and change by the users, and hierarchical roles reflecting game levels may be attached to system rights belonging to individual users and user groups. The prototype we present stems from the question of how to conceive of groupware based on diversity and is the result of combining social theory with algorithms for modelling and visualising user hierarchy and status. Empirical user tests suggest improvements to the prototype’s interface, which will be implemented and further evaluated by embedding the algorithms in a system for e-participation.

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