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  • 1.
    Beltramelli, Luca
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Guntupalli, Lakshmikanth
    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.
    Jennehag, Ulf
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Modeling of Enhanced Distributed Channel Access with Station Grouping: A Throughput Analysis2018In: Proc. IEEE 88th Vehicular Technology Conference (VTC'18-fall), Chicago, USA, Aug. 2018., IEEE conference proceedings, 2018, article id 8690814Conference paper (Refereed)
    Abstract [en]

    Machine to Machine (M2M) communication networksare expected to connect a large number of power constrained devices in long range applications with differentquality of service (QoS) requirements. Medium access control with QoS support such as the Enhanced Distributed Channel Access (EDCA) defined by IEEE 802.11e provides traffic differentiation and corresponding priority classes, which guarantees QoSaccording to the needs of applications. In this paper, we employa station grouping mechanism for enhancing the scalability of EDCA to handle the massive number of access attempts expected in large M2M networks. Furthermore, we develop a discrete time Markov chain (DTMC) model to analyze the performance of EDCA with station grouping. Using the developed DTMC model, we calculate throughput for each access category as well as for different combinations of grouping and EDCA parameters. Thenumerical results show that the model can precisely reveal the behavior of EDCA mechanism. Moreover, it is demonstrated that employing the proposed grouping mechanism for EDCA increasesthe normalized throughput significantly for all classes of priority.

  • 2.
    Beltramelli, Luca
    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.
    Jennehag, Ulf
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Interference Modelling in a Multi-Cell LoRa System2018In: 2018 14th International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob), IEEE, 2018Conference paper (Refereed)
    Abstract [en]

    As the market for low-power wide-area network (LPWAN) technologies expands and the number of connected devices increases, it is becoming important to investigate the performance of LPWAN candidate technologies in dense deployment scenarios. In dense deployments, where the networks usually exhibit the traits of an interference-limited system, a detailed intra- and inter-cell interference analysis of LPWANs is required. In this paper, we model and analyze the performance of uplink communication of a LoRa link in a multi-cell LoRa system. To such end, we use mathematical tools from stochastic geometry and geometric probability to model the spatial distribution of LoRa devices. The model captures the effects of the density of LoRa cells and the allocation of quasi-orthogonal spreading factors (SF) on the success probability of the LoRa transmissions. To account for practical deployment of LoRa gateways, we model the spatial distribution of the gateways with a Poisson point process (PPP) and Matèrn hard-core point process (MHC). Using our analytical formulation, we find the uplink performance in terms of success probability and potential throughput for each of the available SF in LoRa’s physical layer. Our results show that in dense multi-cell LoRa deployment with uplink traffic, the intercell interference noticeably degrades the system performance.

  • 3.
    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%.

  • 4.
    Conti, Caroline
    et al.
    University of Lisbon, Portugal.
    Soares, Luis Ducla
    University of Lisbon, Portugal.
    Nunes, Paulo
    University of Lisbon, Portugal.
    Perra, Cristian
    University of Cagliari, Italy.
    Assunção, Pedro Amado
    Institute de Telecomunicacoes and Politecenico de Leiria, Portugal.
    Sjöström, Mårten
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Li, Yun
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Olsson, Roger
    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.
    Light Field Image Compression2018In: 3D Visual Content Creation, Coding and Delivery / [ed] Assunção, Pedro Amado, Gotchev, Atanas, Cham: Springer, 2018, p. 143-176Chapter in book (Refereed)
  • 5.
    Ferrari, Nico
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Gebremichael, Teklay
    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.
    Lightweight Group-Key Establishment Protocol for IoT Devices: Implementation and Performance Analyses2018In: 2018 Fifth International Conference on Internet of Things: Systems, Management and Security, IEEE, 2018Conference paper (Refereed)
    Abstract [en]

    In the context of Internet of Things (IoT), groupcommunication is an efficient and fast way of broadcastinggroup messages. The message needs to be sent securely tomaintain confidentiality of data and privacy of users. Estab-lishing cryptographically secure communication links betweena group of transceivers requires the pre-agreement upon somekey, unknown to an external attacker. Complex and resource-intensive security schemes are infeasible for devices with limitedcomputational capabilities. In this paper, we implement alightweight and computationally secure group key establish-ment scheme suitable for resource constrained IoT networks.The proposed scheme is based on elliptic curve cryptographyand cryptographic one-way accumulators. We analyze its fea-sibility by implementing it in the Contiki operating system andsimulating it with the Cooja simulator. The simulation resultsdemonstrate the feasibility of the scheme and its computationaland communication costs are also comparable with otherexisting approaches, with an energy consumption of only 109mJ per node for group key establishment.

  • 6.
    Forsgren, Daniel
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Jennehag, Ulf
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Österberg, Patrik
    Objective End-to-End QoS Gain from Packet Prioritization and Layering in MPEG-2 Streaming2002In: International Packetvideo workshop 2002, 2002Conference paper (Other academic)
    Abstract [en]

    Layered video coding as well as prioritized packet scheduling are two well-known methods that may improve the quality of service level in real-time applications with high bandwidth requirements, and are used over packet switched networks. However, it is often difficult to get an idea of, and to quantify, the actual gains that may be achievable, especially from an end-to-end perspective.In this paper, we present some experimental results from using temporally layered MPEG-2 video combined with basic per-layer IP packet prioritization. The goal has been to find out if a basic scheme is useful at all in combination with this particular source coding method, and if so, how much the objective video quality can be increased during bandwidth-constrained periods. The quality is measured in terms of PSNR and the results are compared to the case of equal packet priority. Also, different packet sizes as well as packet queuing disciplines are used. We conclude that using even a relatively simple temporal layering strategy in combination with packet prioritization can quite significantly improve the end-to-end quality of MPEG-2 video, especially in moderately bandwidth constrained situations. Furthermore, packet size and queuing discipline is found to have an impact.

  • 7.
    Forsström, Stefan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Butun, Ismail
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Eldefrawy, Mohamed
    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.
    Challenges of Securing the Industrial Internet of Things Value Chain2018In: 2018 Workshop on Metrology for Industry 4.0 and IoT, MetroInd 4.0 and IoT 2018 - Proceedings, IEEE, 2018, p. 218-223, article id 8428344Conference paper (Refereed)
    Abstract [en]

    We see a shift from todays Internet-of-Things (IoT)to include more industrial equipment and metrology systems,forming the Industrial Internet of Things (IIoT). However, thisleads to many concerns related to confidentiality, integrity,availability, privacy and non-repudiation. Hence, there is a needto secure the IIoT in order to cater for a future with smart grids,smart metering, smart factories, smart cities, and smart manufacturing.It is therefore important to research IIoT technologiesand to create order in this chaos, especially when it comes tosecuring communication, resilient wireless networks, protectingindustrial data, and safely storing industrial intellectual propertyin cloud systems. This research therefore presents the challenges,needs, and requirements of industrial applications when it comesto securing IIoT systems.

  • 8.
    Forsström, Stefan
    et al.
    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.
    A Performance and Cost Evaluation of Combining OPC-UAand Microsoft Azure IoT Hub into an Industrial Internet-of-Things System2017In: GIoTS 2017 - Global Internet of Things Summit, Proceedings, IEEE, 2017, p. 327-332, article id 8016265Conference paper (Refereed)
    Abstract [en]

    The expected monetary costs and response time performance is important information to know before deploying an industrial Internet-of-Things system. The system investigated in this paper is built up by combining the Open Plant Communication Universal Architecture and the Microsoft Azure Internet-of-Things Hub. We consider a real life industrial scenario that remotely monitors a piece of industrial equipment consisting of 1500 sensors, of which 600 update their values every second. The measured results show that the response times for a fiber based Internet connection was on average 770 ms with a standard deviation of 330 ms and the same measurements on a mobile internet connection was on average 1150 ms with a standard deviation of 340 ms. Cost wise, the investigated scenario fits within the most expensive price plan for the IoT hub and ends in a total of just over \$5000 per month for the whole cloud service.

  • 9.
    Forsström, Stefan
    et al.
    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.
    An Implemented Open Source Blockchain Market for Smart Grids and Microgrids Using Autonomous Agents2019In: COINS '19 Proceedings of the International Conference on Omni-Layer Intelligent Systems, ACM Digital Library, 2019, Vol. F148162, p. 116-121Conference paper (Refereed)
    Abstract [en]

    This article presents a system for creating an implemented open energy market for future smart grid systems, microgrids, the Internet of Things, and the Industrial Internet of Things. We also investigate and analyze different aspects of blockchain technologies for this purpose in order to choose the appropriate methods, technologies, and approaches for realizing and implementing the system as an open source project. Based on this analysis, we present our resulting functional implementation of this energy market. Including measurements and a quantitative evaluation of the implementation itself. Showing the potential of the approach, where this implantation can be applied, showing its drawbacks, and finally our planned future work.

  • 10.
    Forsström, Stefan
    et al.
    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.
    Österberg, Patrik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Kardeby, Victor
    Rise Acreo, Hudiksvall.
    Lindqvist, Jonas
    Rise Acreo, Hudiksvall.
    Surveying and Identifying the Communication Platforms of the Internet of Things2018In: 2018 Global Internet of Things Summit (GIoTS), IEEE, 2018, p. 121-126, article id 8534556Conference paper (Refereed)
    Abstract [en]

    Research and industry invest time and resources in producing Internet of Things-based services, and the concept of Internet of Things platforms is climbing in the hype cycle for emerging technologies. Consequently, there is a vast number of enabling technologies, making it difficult to find the most suitable platform. The aim and goal of this article is to list and identify the currently available communication platforms for the Internet of Things. In this work, we surveyed the area and found over \numTot different platforms for communication of data between things and services, out of which \numProm fulfilled our listed basic requirements for being an IoT communication platform.

  • 11.
    Forsström, Stefan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Kardeby, Victor
    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.
    Österberg, Patrik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    A Flexible Sensor and Actuator Gateway for Internet-of-Things Applications2015Conference paper (Refereed)
    Abstract [en]

    There is currently a vast amount of sensors, actuators, and other devices intended to create the Internet-of-Things. However, most of these only operate within a particular manufacturer’s ecosystem and with a limited set of compatible hardware. In response to this we present a general sensor and actuator gateway for the Internet-of-Things, which provides the flexibility to easily exchange sensor and actuator hardware. The gateway is implemented as a proof-of-concept prototype that is verified to be compatible with a wide range of commercial off the shelf hardware. It is also shown to be able to run the SensibleThings platform, a fully distributed and open communication platform for Internet-Things applications.

  • 12.
    Forsström, Stefan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Kardeby, Victor
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Österberg, Patrik
    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.
    Challenges when Realizing a Fully Distributed Internet-of-Things - How we Created the SensibleThings Platform2014In: ICDT 2014, The Ninth International Conference on Digital Telecommunications / [ed] Constantin Paleologu, University Politehnica of Bucharest, Romania Andy Snow, Ohio University, USA, 2014, p. 13-18Conference paper (Refereed)
    Abstract [en]

    The SensibleThings platform is an open source architecturefor enabling Internet-of-Things based applications.During its development, multiple problems have been faced andsolved, for example issues related to networking, information dissemination,sensors, and application access. This paper describesthese problems and the technical solutions that are implementedin the platform. We also present the current progress and aseries of demonstrator applications, which show the wide rangeof possibilities enabled by the platform. Finally, we present futurework and how it will be used in future research endeavors andcommercial interests.

  • 13. 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.))
  • 14. 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
    Reducing a tune-in delay into a scalable encoded data stream2010Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A method for reducing a tune-in delay upon tuning into a scalable encoded data stream is described, wherein the scalable encoded data stream is provided by an encoder and comprises a base layer stream and at least one enhancement layer stream. The base layer stream and the enhancement layer stream are provided from the encoder to a decoder with substantially the same encoder-to-decoder delay.

  • 15. Fuchs, Harald
    et al.
    Döhla, Stefan
    Jennehag, Ulf
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Method and encoder for providing a tune- in stream for an encoded video stream and method and decoder for tuning into an encoded video stream2010Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    For an encoded video stream (200) a tune-in stream (202) is provided. The encoded video stream comprises a plurality of intra-coded pictures and a plurality of inter-coded pictures, wherein each picture comprises a plurality of macroblocks. The encoded video stream (200) comprises a plurality of frames, and the plurality of macroblocks of an intra-coded picture are spread among a plurality of the frames. The tune-in stream is provided and comprises a plurality of tune-in pictures (20212024), wherein a tune-in picture (2021-2024) is provided for a frame of the encoded video stream (200) that comprises an intra-coded macroblock of an intra-coded picture, wherein the tune-in picture (2021-2024) comprises the remaining intra-coded macroblocks of the intra-coded picture. Also, an encoder for providing such a tune-in stream as well as a method and a decoder for tuning into an encoded video stream are described.

  • 16.
    Fuchs, Harald
    et al.
    Fraunhofer IIS, Erlangen.
    Jennehag, Ulf
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thoma, Herbert
    Fraunhofer IIS, Erlangen.
    Subjective evaluation of low resolution tune-in streams for IPTV fast channel change2009In: IEEE International Symposium on Broadband Multimedia Systems and Broadcasting, 2009. BMSB '09., IEEE conference proceedings, 2009, p. 1-5Conference paper (Refereed)
  • 17.
    Fuchs, Harald
    et al.
    Fraunhofer IIS, Erlangen.
    Jennehag, Ulf
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thoma, Herbert
    Fraunhofer IIS, Erlangen.
    Döhla, Stefan
    Fraunhofer IIS, Erlangen.
    Färber, Niko
    Scalable video coding for IPTV fast channel change2009In: Dortmunder Fernsehseminar, 2009Conference paper (Refereed)
  • 18.
    Gebremichael, Teklay
    et al.
    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.
    Lightweight IoT Group Key Establishment Scheme from the One Time Pad2019In: 2019 7th IEEE International Conference on Mobile Cloud Computing, Services, and Engineering (MobileCloud), IEEE, 2019Conference paper (Other academic)
    Abstract [en]

    Secure group communication in the Internet ofThings (IoT) entails the establishment and management of one or more group keys to provide group security services such as confidentiality of group messages. The main challenges in establishing a group key consist in designing a group key establishment scheme that is feasible for nodes with limited computational capabilities. In this paper, we propose a lightweight group key establishment scheme based on fast symmetric-key encryption. We show a mechanism for designing a lightweight and secure IoT group key establishment and management scheme whose security is underpinned by the perfect secrecy provided by the One-time-pad. We then argue that the scheme is convenient for IoT group applications where nodes are resource-constrained. We prove that our scheme is secure under a threat model where the attacker has sufficiently large computational power. We also prove that the scheme provides desired group security properties such as confidentiality, key secrecy and independent group session keys generation.

  • 19.
    Gebremichael, Teklay
    et al.
    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.
    Lightweight IoT Group Key Establishment Scheme Using One-way Accumulator2018In: 2018 International Symposium on Networks, Computers and Communications (ISNCC), IEEE, 2018, article id 8531034Conference paper (Refereed)
    Abstract [en]

    Group communication in the context of Internetof Things (IoT) is an efficient and fast way of broadcasting group messages. A message needs to be sent securely to maintain confidentiality of data and privacy of users. The main challenges in sharing group keys consist in designing and implementing a group key establishment scheme that is feasible for devices with limited computational capabilities. Existing group establishment schemes do not offer a good solution for resource-constrained IoTdevices, a solution that provides secure group key management procedures when new nodes join or leave the group without com-promising the security of the system. In this paper, we propose a light weight and computationally secure group key establishment scheme suitable for resource constrained IoT networks. The proposed scheme is based on elliptic curve cryptography and cryptographic one-way accumulators. We show how to combine the aforementioned concepts to design a group key establishment scheme that guarantees both forward and backward secrecy. Finally, we show how the established group key is updated when the group size dynamically changes and how the proposed solution can be used with block and stream ciphers.

  • 20.
    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)
  • 21.
    Jennehag, Ulf
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Bandwidth Efficient IPTV Distribution: On Error Resilience and Fast Channel Change2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Television is now changing its traditional distribution forms to being distributed digitally over broadband networks. The recent development of broadband Internet connectivity has made the transition to Internet Protocol Television (IPTV) possible. When changing distribution technique of an existing service, it is important that the new technique does not make the service worse from the user’s point of view. Although a broadband network offers high capacity and has excellent performance there will be occasional packet losses and delays which could negatively influence the user experience of the delivered broadband service. Since bandwidth is a key constraint for video distribution there is a strong incentive for finding schemes to increase bandwidth utilization, especially when distributing high bandwidth IPTV services. In digital video coding it is common to use predictive coding to remove temporal redundancy in video sequences. This technique greatly increases the coding efficiency but makes the sequence more sensitive to information loss or delay. In addition, the use of predictive coding also introduce a inter frame dependency which could make the channel change significantly slower.

    This thesis addresses two important areas related to bandwidth efficient IPTV distribution, namely error resilience and fast channel change. A method to numerically estimate the decoded objective video quality of scalable coded video is presented and evaluated. The method can be used to estimate objective video quality for a scalable video transmission system subject to packet-loss. The quality gain of temporally scalable video in a priority packet dropping environment is also investigated and quantified. Synchronization Frames for Channel Switching (SFCS) is proposed as a method to code and distribute video with IP-multicast, which can be used to efficiently combat packet-loss, increase bandwidth utilization, and offer a channel change speed up. The performance of SFCS is analyzed and bandwidth estimation expressions are formulated, analytical results are complemented with computer simulations. The results show that SFCS deployed in an IPTV delivery system can significantly lower the bandwidth consumption and speed up the channel change.

  • 22.
    Jennehag, Ulf
    Kungliga Tekniska Högskolan.
    Video streaming over multicast enabled wired IP networks2005Licentiate thesis, comprehensive summary (Other academic)
  • 23.
    Jennehag, Ulf
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Dohla, S.
    Fraunhofer IIS, Erlangen, Germany.
    Fuchs, H.
    Fraunhofer IIS, Erlangen, Germany.
    Thoma, H.
    Fraunhofer IIS, Erlangen, Germany.
    Gradual tune-in pictures for fast channel change2011In: 2011 IEEE Consumer Communications and Networking Conference, CCNC'2011, IEEE conference proceedings, 2011, p. 766-770Conference paper (Other academic)
    Abstract [en]

    This paper presents a novel approach for fast channel change based on tune-in streams. The presented solution is based on gradual decoder refresh (GDR) with H.264 for the main and for the tune-in stream. In normal GDR mode a receiver would have to wait for several received NAL units of multiple frames before it can render a complete frame without visible GDR artifacts. We propose an additional tune-in stream that fills the missing regions of a partially complete frame. Our simulation results show that the solution is at least as bitrate-efficient as previous tune-in solutions but offers the advantages of a bitstream with less variable bitrate and a consistent gradual improvement of picture quality. © 2011 IEEE.

  • 24.
    Jennehag, Ulf
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Forsström, Stefan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Fiordigigli, Federico V.
    Low delay video streaming on the internet of things using raspberry Pi2016In: Electronics (Switzerland), ISSN 2079-9292, Vol. 5, no 3, article id 60Article in journal (Refereed)
    Abstract [en]

    The Internet of Things is predicted to consist of over 50 billion devices aiming to solve problems in most areas of our digital society. A large part of the data communicated is expected to consist of various multimedia contents, such as live audio and video. This article presents a solution for the communication of high definition video in low-delay scenarios (<200 ms) under the constraints of devices with limited hardware resources, such as the Raspberry Pi. We verify that it is possible to enable low delay video streaming between Raspberry Pi devices using a distributed Internet of Things system called the SensibleThings platform. Specifically, our implementation transfers a 6 Mbps H.264 video stream of 1280 × 720 pixels at 25 frames per second between devices with a total delay of 181 ms on the public Internet, of which the overhead of the distributed Internet of Things communication platform only accounts for 18 ms of this delay. We have found that the most significant bottleneck of video transfer on limited Internet of Things devices is the video coding and not the distributed communication platform, since the video coding accounts for 90% of the total delay.

  • 25.
    Jennehag, Ulf
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Pettersson, Stefan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    On Synchronization Frames for Channel Switching in a GOP-based IPTV Environment2008In: 2008 5TH IEEE CONSUMER COMMUNICATIONS AND NETWORKING CONFERENCE, VOLS 1-3, New York: IEEE conference proceedings, 2008, p. 638-642Conference paper (Refereed)
    Abstract [en]

    Traditionally, Group of Pictures (GOP) is used to solve IPTV channel tune-in issues. However, channel changes issued by a TV viewer are quite rare which indicates it is redundant to solve channel tune-in with GOP. In this paper we extend our earlier work on Synchronization Frames for Channel Switching (SFCS) for reducing bandwidth utilization in IPTV networks to include encoding/decoding standards not supporting SI/SP-frames. We propose modifications to SFCS to work with MPEG-2. Channel tune-in quality and synchronization stream generation is also addressed. We provide bandwidth estimation expressions which are verified with an experimental simulation. Results show that SFCS adapted to MPEG-2 can reduce the bandwidth utilization with 9% compared to a traditional GOP system with equal steady state quality.

  • 26.
    Jennehag, Ulf
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Zhang, Tingting
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Increasing bandwidth utilization in next generation IPTV networks2004In: ICIP: 2004 INTERNATIONAL CONFERENCE ON IMAGE PROCESSING, VOLS 1- 5, IEEE conference proceedings, 2004, p. 2075-2078Conference paper (Refereed)
    Abstract [en]

    In this paper we present a novel idea regarding transmission of next generation IPTV content. Today IPTV systems utilize a COP structure tu provide stream synchronization points for the clients, these are used when a channel switch occur. Since channel switches made by TV audiences are quite rare it is redundant to send synchronization opportunities in a GOP manner. The proposed design, synchronization frames fur channel switching (SFCS), only requests synchronization frames when needed. We present a network traffic analysis model and compare it with simulations. SFCS increases bandwidth utilization compared to traditional COP system under the presented transmission environment.

  • 27.
    Jennehag, Ulf
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Zhang, Tingting
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Pettersson, Stefan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Improving transmission efficiency in H.264 based IPTV systems2007In: IEEE transactions on broadcasting, ISSN 0018-9316, E-ISSN 1557-9611, Vol. 53, no 1, p. 69-78Article in journal (Refereed)
    Abstract [en]

    In this paper, a novel proposal regarding the transmission of the next generation of live-TV content in an IPTV environment is presented. Today live-TV IP transmission systems utilizes a Group Of Pictures (GOP) structure in order to provide stream synchronization points for the clients. Synchronization points are used when a TV-channel switch occurs. The number of channel switches made by TV audiences have been shown to be rather rare. It is therefore redundant to send synchronization events in a GOP manner. Our proposal, Synchronization Frames for Channel Switching (SFCS), only requests synchronization points when required. Due to channel popularity distributions and the number of connected users, the total number of synchronization requests for a popular channel can increase to a level that makes SFCS less effective than GOP. Therefore, we introduce an SFCS-GOP hybrid. A complete network traffic analysis model, verified by a simple simulation environment, is also presented and the results show that the SFCS-GOP hybrid significantly increases the bandwidth utilization compared to a traditional GOP system

  • 28.
    Kanter, Theo
    et al.
    Department of Computer and System Sciences Stockholm University.
    Forsström, Stefan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Kardeby, Victor
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Walters, Jamie
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Jennehag, Ulf
    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.
    MediaSense – an Internet of Things Platform for Scalable and Decentralized Context Sharing and Control2012Conference paper (Refereed)
    Abstract [en]

    Research in Internet-of-Things infrastructures hasso far mainly been focused on connecting sensors and actuatorsto the Internet, while associating these devices to applicationsvia web services. This has contributed to making the technologyaccessible in areas such as smart-grid, transport, health, etc.These early successes have hidden the lack of support forsensor-based applications to share information and limitationsin support for applications to access sensors and actuatorsglobally. We address these limitations in an novel open-sourceplatform, MediaSense. MediaSense offers scalable, seamless,real-time access to global sensors and actuators via hetero-geneous network infrastructure. This paper presents a setof requirements for Internet-of-Things applications support,an overview of our architecture, and application prototypescreated in order to verify the approach in a test bed withusers connected from heterogeneous networks.

  • 29.
    Kardeby, Victor
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Forsström, Stefan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Österberg, Patrik
    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.
    Fully Distributed Ubiquitous Information Sharing on a Global Scale for the Internet-of-Things2014In: International Journal On Advances in Telecommunications, ISSN 1942-2601, E-ISSN 1942-2601, Vol. 7, no 3 & 4, p. 69-81Article in journal (Refereed)
    Abstract [en]

    The Internet-of-Things will require ubiquitous informationsharing between connected things on a global scale, whichexisting systems do not offer. Most current efforts focus on solutionsfor information dissemination, which induce single pointsof failure and introduce unnecessary communication delays. Tothis end we propose the SensibleThings platform, which is afully distributed open source architecture for Internet-of-Thingsbased applications. This article describes the major problems thatInternet-of-Things platforms must address, our technical solutionto these problems, and an evaluation thereof. We also present thecurrent progress and a series of demonstrators, which show thewide range of applications enabled by the platform. Finally, wepresent how the platform will be used in our future research andpotential spin off companies.

  • 30.
    Kardeby, Victor
    et al.
    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.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Overlay Enhanced Mobility for the Internet of Things2015In: Journal of Networks, ISSN 1796-2056, E-ISSN 1796-2056, Vol. 10, no 7, p. 420-430Article in journal (Refereed)
    Abstract [en]

    One of the major challenges to realize the Internet of Things is to support IP mobility for the large amount of connected entities when they move between different locations and access methods. Current solutions for mobility are host centric, requiring support from the infrastructure, or breaks backwards compatibility, which will take a long time or high economic motivation to implement. Solutions for context information exchange are created for specific, small, or localized scenarios with centralized coordination that do not scale well. There is therefore a need for a solution which both scales well, and support IP mobility, without additional demands on current or future Internet infrastructure.We propose the use of a dual-overlay network structure for both information dissemination and as an alternative to current IP mobility technologies. It separates identities from location by introducing a second overlay network where the identity-to-location association is stored. We show analytically that the proposed solution provide logarithmic latency for localization and reduces the overall workload when the number of sensors per host increases beyond seven, with a workload reduction of 15 percentage points at fifteen sensors per host.

  • 31.
    Kardeby, Victor
    et al.
    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.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Power consumption for global information dissemination in the Internet of Things2015In: 2015 IEEE 10th International Conference on Intelligent Sensors, Sensor Networks and Information Processing, ISSNIP 2015, 2015, p. Art. no. 7106933-Conference paper (Refereed)
    Abstract [en]

    The Internet of Things is a research topic, where billions of things, both sensing and actuating, connect to the Internet, interact, exchange information and enable intelligent services. Current resource consumption models are adapted to information distribution where the cost of information gathering is neglected. However, the emerging Internet of Things will contain billions of sensors that are capable of producing information in real-time, which both demand more resources, and is of interest to fewer users. In this paper, we present an analytical power model for both information collection and distribution in order to find the total power consumption of the Internet of Things. We apply the model to both a centralized and a distributed scenario where billions of devices produce and consume sensor information continuously. We find through analysis that there is a reduced power consumption for content traffic in distributed solutions when compared with centralized solutions for equal numbers of devices, sensors, and users. Thus, we conclude that a fully distributed solution for information gathering and dissemination is preferable to centralized solutions for retrieving the current version of information that changes often.

  • 32.
    Kardeby, Victor
    et al.
    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.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Surveying indexing methods for the Internet of things2016In: Internet of Things. IoT Infrastructures: Second International Summit, IoT 360° 2015, Rome, Italy, October 27-29, 2015, Revised Selected Papers, Part II, Springer, 2016, Vol. 170, p. 282-291Conference paper (Refereed)
    Abstract [en]

    The Internet of Things is expected to expand several magnitudes in the coming decade surpassing over 50 billion devices. In the Internet of Things there is a need to support complex queries on the massive amount of information that will be made available. The scalability of the indexes used to support the queries is therefore critical. This paper therefore investigate what type of index that could scale to the size required by the Internet of Things. We find that range query is an approach that support continuously changing information and fast updates with the lowest increase in signaling per participating device.We find that a Chord-based distributed hash table hosting a NUBL range query indexing scheme will scale to the required size while supporting multidimensional range queries.

  • 33.
    Lavassani, Mehrzad
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Forsström, Stefan
    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.
    Zhang, Tingting
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Combining Fog Computing with Sensor Mote Machine Learning for Industrial IoT2018In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 18, no 5, article id 1532Article in journal (Refereed)
    Abstract [en]

    Digitalization is a global trend becoming ever more important to our connected and sustainable society. This trend also affects industry where the Industrial Internet of Things is an important part, and there is a need to conserve spectrum as well as energy when communicating data to a fog or cloud back-end system. In this paper we investigate the benefits of fog computing by proposing a novel distributed learning model on the sensor device and simulating the data stream in the fog, instead of transmitting all raw sensor values to the cloud back-end. To save energy and to communicate as few packets as possible, the updated parameters of the learned model at the sensor device are communicated in longer time intervals to a fog computing system. The proposed framework is implemented and tested in a real world testbed in order to make quantitative measurements and evaluate the system. Our results show that the proposed model can achieve a 98% decrease in the number of packets sent over the wireless link, and the fog node can still simulate the data stream with an acceptable accuracy of 97%. We also observe an end-to-end delay of 180 ms in our proposed three-layer framework. Hence, the framework shows that a combination of fog and cloud computing with a distributed data modeling at the sensor device for wireless sensor networks can be beneficial for Industrial Internet of Things applications.

  • 34.
    Li, Yun
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Sjöström, Mårten
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Jennehag, Ulf
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Olsson, Roger
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    A Scalable Coding Approach for High Quality Depth Image Compression2012In: 3DTV-Conference, IEEE conference proceedings, 2012, p. Art. no. 6365469-Conference paper (Refereed)
    Abstract [en]

    The distortion by using traditional video encoders (e.g. H.264) on the depth discontinuity can introduce disturbing effects on the synthesized view. The proposed scheme aims at preserving the most significantdepth transition for a better view synthesis. Furthermore, it has a scalable structure. The scheme extracts edge contours from a depth image and represents them by chain code. The chain code and the sampleddepth values on each side of the edge contour are encoded by differential and arithmetic coding. The depthimage is reconstructed by diffusion of edge samples and uniform sub-samples from the low quality depthimage. At low bit rates, the proposed scheme outperforms HEVC intra at the edges in the synthesized views, which correspond to the significant discontinuities in the depth image. The overall quality is also better with the proposed scheme at low bit rates for contents with distinct depth transition. © 2012 IEEE.

  • 35.
    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.
    Jennehag, Ulf
    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.
    Depth Image Post-processing Method by Diffusion2013In: Proceedings of SPIE-The International Society for Optical Engineering: 3D Image Processing (3DIP) and Applications, SPIE - International Society for Optical Engineering, 2013, p. Art. no. 865003-Conference paper (Refereed)
    Abstract [en]

    Multi-view three-dimensional television relies on view synthesis to reduce the number of views being transmitted.  Arbitrary views can be synthesized by utilizing corresponding depth images with textures. The depth images obtained from stereo pairs or range cameras may contain erroneous values, which entail artifacts in a rendered view. Post-processing of the data may then be utilized to enhance the depth image with the purpose to reach a better quality of synthesized views. We propose a Partial Differential Equation (PDE)-based interpolation method for a reconstruction of the smooth areas in depth images, while preserving significant edges. We modeled the depth image by adjusting thresholds for edge detection and a uniform sparse sampling factor followed by the second order PDE interpolation. The objective results show that a depth image processed by the proposed method can achieve a better quality of synthesized views than the original depth image. Visual inspection confirmed the results.

  • 36.
    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.
    Jennehag, Ulf
    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.
    Depth Map Compression with Diffusion Modes in 3D-HEVC2013In: MMEDIA 2013 - 5th International Conferences on Advances in Multimedia / [ed] Philip Davies, David Newell, International Academy, Research and Industry Association (IARIA), 2013, p. 125-129Conference paper (Refereed)
    Abstract [en]

    For three-dimensional television, multiple views can be generated by using the Multi-view Video plus Depth (MVD) format. The depth maps of this format can be compressed efficiently by the 3D extension of High Efficiency Video Coding (3D-HEVC), which has explored the correlations between its two components, texture and associated depth map. In this paper, we introduce two modes for depth map coding into HEVC, where the modes use diffusion. The framework for inter-component prediction of Depth Modeling Modes (DMM) is utilized for the proposed modes. They detect edges from textures and then diffuse an entire block from known adjacent blocks by using Laplace equation constrained by the detected edges. The experimental results show that depth maps can be compressed more efficiently with the proposed diffusion modes, where the bit rate saving can reach 1.25 percentage of the total depth bit rate with a constant quality of synthesized views.

  • 37.
    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.
    Jennehag, Ulf
    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.
    Tourancheau, Sylvain
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Subjective Evaluation of an Edge-based Depth Image Compression Scheme2013In: Proceedings of SPIE - The International Society for Optical Engineering: Stereoscopic Displays and Applications XXIV, SPIE - International Society for Optical Engineering, 2013, p. Art. no. 86480D-Conference paper (Refereed)
    Abstract [en]

    Multi-view three-dimensional television requires many views, which may be synthesized from two-dimensional images with accompanying pixel-wise depth information. This depth image, which typically consists of smooth areas and sharp transitions at object borders, must be consistent with the acquired scene in order for synthesized views to be of good quality. We have previously proposed a depth image coding scheme that preserves significant edges and encodes smooth areas between these. An objective evaluation considering the structural similarity (SSIM) index for synthesized views demonstrated an advantage to the proposed scheme over the High Efficiency Video Coding (HEVC) intra mode in certain cases. However, there were some discrepancies between the outcomes from the objective evaluation and from our visual inspection, which motivated this study of subjective tests. The test was conducted according to ITU-R BT.500-13 recommendation with Stimulus-comparison methods. The results from the subjective test showed that the proposed scheme performs slightly better than HEVC with statistical significance at majority of the tested bit rates for the given contents.

  • 38.
    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.

  • 39.
    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.
    Efficient Intra Prediction Scheme For Light Field Image Compression2014In: ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings, IEEE conference proceedings, 2014, p. Art. no. 6853654-Conference paper (Refereed)
    Abstract [en]

    Interactive photo-realistic graphics can be rendered by using light field datasets. One way of capturing the dataset is by using light field cameras with microlens arrays. The captured images contain repetitive patterns resulted from adjacent mi-crolenses. These images don't resemble the appearance of a natural scene. This dissimilarity leads to problems in light field image compression by using traditional image and video encoders, which are optimized for natural images and video sequences. In this paper, we introduce the full inter-prediction scheme in HEVC into intra-prediction for the compression of light field images. The proposed scheme is capable of performing both unidirectional and bi-directional prediction within an image. The evaluation results show that above 3 dB quality improvements or above 50 percent bit-rate saving can be achieved in terms of BD-PSNR for the proposed scheme compared to the original HEVC intra-prediction for light field images.

  • 40.
    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.

  • 41.
    Pau, Giovanni
    et al.
    Kore University of Enna, Enna, Italy.
    Ferrero, Renato
    Politecnico di Torino, Italy.
    Jennehag, Ulf
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Zhang, Haijun
    University of Science and Technology Beijing, China.
    Emerging applications through low-power wireless technologies for Internet of Things2019In: International Journal of Distributed Sensor Networks, ISSN 1550-1329, E-ISSN 1550-1477, Vol. 15, no 3Article in journal (Refereed)
  • 42.
    Qureshi, Umair Mujtaba
    et al.
    City University of Hong Kong.
    Hancke, Gerhard Petrus
    City University of Hong Kong.
    Gebremichael, Teklay
    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.
    Forsström, Stefan
    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.
    Survey of Proximity Based Authentication Mechanisms for the Industrial Internet of Things2018In: IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society, IEEE, 2018Conference paper (Refereed)
    Abstract [en]

    In this paper we present an overview of the variousproximity based authentication mechanisms that can be usedin the Industrial Internet of Things (IIoT). We seek to identifyand highlight from a holistic point of view which mechanismscan enable proximity based authentication for the IndustrialInternet of Things. In addition, we identify which upcomingproximity authentication mechanisms are most important for theproliferation of the Industrial Internet of Things, and highlightmajor obstacles that remain unsolved with regard to authen-tication. In answering this, we present seven mechanisms forproximity based authentication (i.e. wire, radio, acoustics, light,image, gesture and biometrics) and discuss each mechanism inperspective of their vulnerability to different kind of attacks (suchas eavesdropping, impersonation and denial of service attacksetc.) and their usability (such as proximity range, hardwarerequirement and ease of use) in terms of the practicality in IIoTenvironment in the light of which we present two typical IIoTuse cases that require proximity based authentication.

  • 43.
    Sisinni, Emiliano
    et al.
    University of Brescia.
    Saifullah, Abusayed
    Wayne State University, USA.
    Han, Song
    University of Connecticut, USA.
    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.
    Industrial Internet of Things: Challenges, Opportunities, and Directions2018In: IEEE Transactions on Industrial Informatics, ISSN 1551-3203, E-ISSN 1941-0050, Vol. 14, no 11, p. 4724-4734Article in journal (Refereed)
    Abstract [en]

    Internet of Things (IoT) is an emerging domain that promises ubiquitous connection to the Internet, turning common objects into connected devices. The IoT paradigm is changing the way people interact with things around them. It paves the way to creating pervasively connected infrastructures to support innovative services and promises better flexibility and efficiency. Such advantages are attractive not only for consumer applications, but also for the industrial domain. Over the last few years, we have been witnessing the IoT paradigm making its way into the industry marketplace with purposely designed solutions. In this paper, we clarify the concepts of IoT, Industrial IoT, and Industry 4.0. We highlight the opportunities brought in by this paradigm shift as well as the challenges for its realization. In particular, we focus on the challenges associated with the need of energy efficiency, real-time performance, coexistence, interoperability, and security and privacy. We also provide a systematic overview of the state-of-the-art research efforts and potential research directions to solve Industrial IoT challenges.

  • 44.
    Zanni, Alessandro
    et al.
    University of Bologna, Italy.
    Forsström, Stefan
    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.
    Bellavista, Paolo
    University of Bologna, Italy.
    Elastic Provisioning of Internet of Things Services using Fog Computing: an Experience Report2018In: 2018 6th IEEE International Conference on Mobile Cloud Computing, Services, and Engineering (MobileCloud), IEEE, 2018, p. 17-22Conference paper (Refereed)
    Abstract [en]

    The adoption of cloud and fog computing techniquesfor elastic provisioning of quality-constrained industrial Internet of Things (IoT) services is largely envisioned as very promising, but experience reports and lessons learned from real deployment still lack. To fill this gap, this paper presents andreports the evaluation of a system consisting of virtual services in a combined fog, cloud, and IoT setting, made up of multiple devices with varying computation capabilities. In particular,we have utilized and integrated off-the-shelf solutions into our architecture and have experimentally investigated the benefits of virtualization to move and redeploy mobile components to the fog nodes closest to the targeted end devices. In addition, the paper proposes an original solution to dynamically scale and provision the resources for the fog computing layer by using geometric monitoring. The reported results show the feasibility and efficiency of the proposed exploitation of both fog and cloud virtualized resources to enable scalability in the domain of IoT-assisted mobile presence services.

  • 45.
    Zhang, Tingting
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Jennehag, Ulf
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Xu, Youshi
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Numerical modeling of transmission errors and video quality of MPEG-22001In: Signal processing. Image communication, ISSN 0923-5965, E-ISSN 1879-2677, Vol. 16, no 8, p. 817-825Article in journal (Refereed)
    Abstract [en]

    To efficiently combat the signal loss of MPEG-2 transmission over unreliable networks, priority encoding transmission, unequal packet loss protection and priority dropping techniques have been studied in many papers. Those studies are based on the qualitative analysis of different importance of signals, without quantitative investigation of signal loss effect on video quality. In this paper, MPEG-2 packet loss effect on video quality is quantitatively investigated, a temporal layered signal model is described and evaluated, a quality measure for reconstructed pictures called macroblock impairment ratio is suggested and defined. The investigation and the model are specified for MPEG-2, but the principles and the methods are suitable for any layered video. These are useful for the development of efficient schemes and protocols for packet video transmission over unreliable networks.

  • 46.
    Zhang, Tingting
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Jennehag, Ulf
    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.
    Numerical modeling of transmission errors and video quality of MPEG-22000In: Packet Video 2000: Proceedings. 10th International Packet Video Workshop, Cagliari, Sardinia, Italy, May 1-2 2000, 2000Conference paper (Other academic)
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