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  • 1.
    Eriksson, Magnus
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Xu, Youzhi
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Packet-by-packet Radio Resource Management by means of Dynamic Single Frequency Networks: The 2000 International Conference on Broadband Wireless Access Systems (WAS'00), San Fransisco, U.S.A., December 4-6, 20002000Konferansepaper (Annet vitenskapelig)
    Abstract [en]

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

  • 2.
    Gidlund, Mikael
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Xu, Youzhi
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    An Improved ARQ Scheme with Applications to Multi-Level Modulation Techniques2004Inngår i: ISCIT 2004: Proceedings of International Symposium on Communications and Information Technologies 2004, IEEE , 2004Konferansepaper (Annet vitenskapelig)
  • 3.
    Gidlund, Mikael
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Xu, Youzhi
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Enhancement of Throughput and Range in HIPERLAN/2 System using Space-Time Coding2002Inngår i: IEEE European Conference on Wireless Technology (ECWT 2006), 2002Konferansepaper (Annet vitenskapelig)
  • 4.
    Gidlund, Mikael
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Xu, Youzhi
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Performance Evaluation of ARQ Error Control Schemes in HIPERLAN/2 Systems2002Konferansepaper (Annet vitenskapelig)
  • 5.
    Gidlund, Mikael
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Xu, Youzhi
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Performance of Enhanced ARQ Scheme Suitable for Multi-Level Modulation Techniques2004Inngår i: Proceedings of IEEE ISITA'04, Parma, Italy, October 2004, 2004Konferansepaper (Fagfellevurdert)
  • 6.
    Gidlund, Mikael
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Yang, Dong
    Beijing Jiatong University.
    Xu, Youzhi
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Shen, Wei
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Zhang, Tingting
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Wireless communication method and system with collision avoidance protocol2012Patent (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    The invention concerns a method for providing wireless communication between a source node and a destination node in a wireless network wherein said wireless network uses a time division multiple access (TDMA) protocol. One or more dedicated TDMA transaction timeslots (60-71) are arranged in a superframe. The superframe comprises at least one dedicated transaction slot forming a hybrid protocol with two or more shared transaction slots 50 per superframe. The method is of particular advantage when practised with a WirelessHART protocol wireless sensor network and when used for monitoring and control equipment and processes in an industrial installation. A computer program, and a wireless node and a wireless network using the inventive method are also disclosed.

  • 7.
    Huo, Hong-wei
    et al.
    Beijing Jiatong University.
    Xu, You-zhi
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier. Data Communication, School of Engineering, Jönköping University, Jönköping, Sweden.
    Gidlund, Mikael
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier. ABB Corporate Research.
    Zhang, Hong-ke
    School of Electronic and Information Engineering, Beijing Jiaotong University, Beijing 100044, China.
    Coexistence of 2.4 GHz sensor networks in home environment2010Inngår i: The Journal of China Universities of Posts and Telecommunications, ISSN 1005-8885, Vol. 17, nr 1, s. 9-18Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The IEEE 802.15.4 is one of the low-layer communication standards for personal area networks (PANs) and wireless sensor networks (WSNs), which may be interfered by other wireless devices in the industrial, scientific and medical (ISM) frequency bands, especially in home environment, such as devices of IEEE 802.11b, Bluetooth, cordless telephone, and microwave oven radiation. This article examines the mutual interference effects of 2.4 GHz devices widely deployed at home, via both theoretical analysis and real-life experiment. An analytical model is proposed to estimate the packet error rate (PER) of radio frequency (RF) coexistent networks. The model is verified through a series of experiments. The experimental results also show that Bluetooth has little impact of interference on IEEE 802.15.4 sensor networks, and that the effect of microwave oven radiation on IEEE 802.15.4 sensor devices is tolerable if the device is a few meters away from the oven. Whereas, IEEE 802.11b wireless networks can cause problems to IEEE 802.15.4, however the effects can be significantly reduced by a proper channel selection. This article also proposes the interference duration model, which will be helpful in modeling of coexistence simulation. Simulation results show that the stationary scenario obeys the experiments result very well.

  • 8.
    Norell, Håkan
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Oelmann, Bengt
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Xu, Youshi
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Spatio-Temporal Noise Reduction algorithm targeting Real-Time Video Processing2000Inngår i: Proceedings of IEEE International Symposium on Information Theory and Its Applications 2000, 2000Konferansepaper (Fagfellevurdert)
  • 9.
    Norell, Håkan
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Oelmann, Bengt
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Xu, Youshi
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Spatio-Temporal Noise Reduction ASIC for Real-Time Noise Reduction ASIC Processing2000Inngår i: Proceedings of 2000 IEEE Nordic Signal Processing Symposium, 2000Konferansepaper (Fagfellevurdert)
  • 10. Olsson, K
    et al.
    Andersson, Roger
    Zhang, TingTing
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Xu, Youshi
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    A Fast Implementation Scheme for 2-D Discrete Cosine Transform1997Patent (Annet (populærvitenskap, debatt, mm))
  • 11. Olsson, K
    et al.
    Andersson, Roger
    Zhang, TingTing
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Xu, Youshi
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Digital Video Temporal Noise Reduction1997Patent (Annet (populærvitenskap, debatt, mm))
  • 12.
    Olsson, Roger
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Sjöström, Mårten
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Xu, Youshi
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Evaluation of Combined Pre-processing and H.264-compression Schemes for 3D Integral Images2006Rapport (Annet vitenskapelig)
  • 13.
    Olsson, Roger
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Sjöström, Mårten
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Xu, Youzhi
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    A combined pre-processing and H.264-compression scheme for 3D integral images2006Inngår i: Proceedings International Conference on Image Processing, Vols 1-7, Atlanta, GA: IEEE , 2006, s. 513-516Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The next evolutionary step in enhancing video communication fidelity is taken by adding scene depth. 3D video using integral imaging (II) is widely considered as the technique able to take this step. However, an increase in spatial resolution of several orders of magnitude from todays 2D video is required to provide a sufficient depth fidelity. In this paper we propose a pre-processing method that aims to enhance the compression efficiency of integral images. We first transform a still integral image into a pseudo video sequence which is then compressed using a H.264 video encoder. The improvement in compression efficiency of using this combination of pre-processing and compression is evaluated and presented. An average PSNR increase of 6.9 dB or more, compared to JPEG2000, is observed on a set of reference images.

  • 14.
    Olsson, Roger
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Sjöström, Mårten
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Xu, Youzhi
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Evaluation of combined pre-processing and H.264-compression schemes for 3D integral images2007Inngår i: Visual Communications and Image Processing 2007, Pts 1 and 2, Bellingham, Wash.: SPIE , 2007, Vol. 6508, artikkel-id 65082CKonferansepaper (Fagfellevurdert)
    Abstract [en]

    Abstract Integral imaging is widely considered as a promising technique able to enhance video by adding scene depth, i.e. producing 3D video. However, an increase in spatial resolution of several orders of magnitude from todays 2D video is required to provide a sufficient depth fidelity. We have recently proposed a pre-processing and compression scheme for integral images showing good performance on a set of reference images. This scheme forms pseudo video sequences by transforming the static integral image into a set of orthoscopic projections, so called modified elementary images. The pseudo video sequence is then compressed using H.264 compression. In this paper we investigate how different orders of selecting the modified elementary images affect the schemes compression efficiency. Five different selection orders are evaluated on four reference images. The performance of each combination of selection order and reference image is presented. The obtained results indicate that for all but the most complex reference image, all selection order can provide a compression ratio of 320:1 or more, while keeping PSNR above 30 dB.

  • 15.
    Olsson, Roger
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Xu, Youzhi
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    A Ray-Tracing Based Simulation Environment for Generating Integral Imaging Source Material2005Inngår i: Radiovetenskap och Kommunikation, Linköping, Sverige, den 14 juni 2005 - den 16 juni 2005., 2005, s. 663-666Konferansepaper (Fagfellevurdert)
  • 16.
    Olsson, Roger
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Xu, Youzhi
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier. Dep. of Electrical and Computer Engineering, Jönköping Univ., Jönköping.
    An Interactive Ray-tracing based simulation environment for generating integral imaging video sequences2005Inngår i: Proceedings of SPIE - The International Society for Optical Engineering, Society of Photo-Optical Instrumentation Engineers , 2005, Vol. 6016, s. 60160F-1-60160F-8, artikkel-id 60160FKonferansepaper (Fagfellevurdert)
    Abstract [en]

    The next evolutionary step in enhancing video communication fidelity over wired and wireless networks is taken by adding scene depth. Three-dimensional video using integral imaging (II) based capture and display subsystems has shown promising results and is now in the early prototype stage. We have created a ray-tracing based interactive simulation environment to generate II video sequences as a way to assist in the development, evaluation and quick adoption of these new emerging techniques into the whole communication chain. A generic II description model is also proposed as the base for the simulation environment. This description model facilitate optically accurate II rendering using MegaPOV, a customized version of the open-source ray tracing package POV-Ray. By using MegaPOV as a rendering engine the simulation environment fully incorporate the scene description language of POV-Ray to exactly define a virtual scene. Generation and comparability of II video sequences adhering to different II-techniques is thereby greatly assisted, compared to experimental research. The initial development of the simulation environment is focused on generating and visualizing II source material adhering to the optical properties of different II-techniques published in the literature. Both temporally static as well as dynamic systems are considered. The simulation environment's potential for easy deployment of integral imaging video sequences adhering to different II-techniques is demonstrated.

  • 17.
    Timilsina, M.
    et al.
    Department of Electrical Engineering, Jönköping University, Sweden .
    Xu, Youzhi
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Gidlund, Mikael
    ABB Corporate Research, Sweden .
    Comparison between single mesh network and cell based mesh network2012Inngår i: 2012 International Conference on Wireless Communications, Networking and Mobile Computing, WiCOM 2012, IEEE conference proceedings, 2012, s. Art. no. 6478456-Konferansepaper (Fagfellevurdert)
    Abstract [en]

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

  • 18.
    Wang, Hongchao
    et al.
    Beijing Jiaotong Univ, Beijing, Peoples R China.
    Ma, Jian
    Beijing Jiaotong Univ, Beijing, Peoples R China.
    Xu, Youzhi
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för informationssystem och -teknologi.
    Yang, Dong
    Beijing Jiaotong Univ, Beijing, Peoples R China.
    Zhang, Hongke
    Beijing Jiaotong Univ, Beijing, Peoples R China.
    A Bandwidth-Efficient MAC Scheme for Mission-Critical Applications in Industrial Wireless Sensor Networks2018Inngår i: Journal of Internet Technology, ISSN 1607-9264, E-ISSN 2079-4029, Vol. 19, nr 3, s. 795-805Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Industrial wireless sensor networks (IWSNs) have the potential to contribute significantly to a variety of wireless sensing endpoints, such as cable replacement, mobility, flexibility and cost reduction. However, the harsh and varied industrial environment entails addressing severe challenges, such as dust, heat, electromagnetic interference (EMI) and radio frequency interference from the other heterogeneous networks. One of the important challenges is the link burstiness in industrial wireless environments, which has not been heavily researched. In this paper, we propose a new timeslot scheduling algorithm to address this problem. The algorithm allows transmissions on the same link to be separated at least by a minimum timeslot distance. Moreover, to provide a synergistic complement to the timeslot scheduling, we also propose a timeslot reuse scheme, which facilitates improved efficiency and reliability in the bandwidth utilization and retransmission and decreases the average delay of the packet arrival. We evaluate the proposed algorithm and scheme by a real implementation, targeting a specific industrial application. The experimental results generally indicate that the proposed media access control (MAC) scheme greatly improves the reliability and decreases the packet arrival delay. Compared with the existing popular methods, the execution of our scheme indicates a minimal link burstiness influence and possesses more efficient bandwidth utilization.

  • 19.
    Xu, Y S
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    CS-PRMA/AP: Carrier sense packet reservation multiple access with adaptive permission probability2000Inngår i: 2000 INTERNATIONAL CONFERENCE ON COMMUNICATION TECHNOLOGY PROCEEDINGS, VOLS. I & II / [ed] Ke G; Zhisheng N, BEIJING: PUBLISHING HOUSE ELECTRONICS INDUSTRY , 2000, s. 892-899, artikkel-id 889334Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In the paper a Carrier Sense Packet Reservation Multiple Access (CS-PRMA) protocol is proposed for Wireless Local Area Networks (WLAN). The proposed protocol can be viewed as a combination of CSMA with adaptive permission probability for contentions and TDMA for reserved transmissions. A mechanism for the sense of hidden transmitting terminals is described. As the original PRMA the CS-PRMA system has the properties of soft capacity, soft hand-over, and distributed slot assignment and selection. The basic feature that characterises CS-PRMA with respect to original PRMA is its very high channel efficiency. Simulation shows that a capacity of 2.50 conversations per slot is achievable for a broadband communication system with fast speech activity detectors. This capacity is close to the upper bound of the PRMA capacity, 2.78 conversations per slot. Furthermore the consecutive contention scheme is very flexible for different traffics with different priorities, such as voice, network control signals and data messages. This protocol is suitable for broadband WLANs, where a high degree of distributed system control is required.

  • 20. Xu, Youshi
    A modified Euclidean algorithm and the VLSI implementation1996Inngår i: 8th Mediterranean Electrotechnical Conference, 1996. MELECON '96., Bari, Italy, 13-16 May 1996. Vol. 3, 1996, s. 1324-1327Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The extended Euclidean algorithm is important in algebraic and symbolic computations, in error correcting codes, in code division multiple access and, in cryptology. We propose a modified algorithm and a recursive implementation. Both the time and space complexity of the implementation is better than conventional ones. The regular and modular construction implies that it can be implemented on VLSI chips. The implementation can be used in decoding BCH codes, RS codes and Goppa codes. A throughput of hundreds of megabits per second is achievable.

  • 21.
    Xu, Youshi
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Efficient integration of voice and data services in wireless local area networks2000Inngår i: EEE Vehicular Technology Conference, IEEE conference proceedings, 2000, Vol. 2, s. 1395-1399Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We propose a new scheme of mixing speech information, network control message and data information with different priority in PRMA. This proposed PRMA can be viewed as a combined protocol of voice-only PRMA for voice terminals, carrier sense (CS)-slotted ALOHA for network control and CS-TDMA for data terminals. A mechanism for the sensing of hidden transmitting terminals is described. The integrated control packets and data packets do not have any influence on voice transmission. Simulation results show that the delay of network control packets and the channel throughput can be significantly improved, compared to all the other integrated PRMA protocols. This protocol distributes major control to the terminals, which may be extremely useful and important in the future.

  • 22.
    Xu, Youshi
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Pure Binary BCH Concatenated Codes and the Applications for Fading Channels1996Inngår i: Radiovetenskap och Kommunikation, 3-5 June 1996, Luleå, Sweden, 1996Konferansepaper (Fagfellevurdert)
  • 23. Xu, Youshi
    et al.
    Nilsson, P
    Wiklund, H
    Packet Reservation Multiple Access for Joint Voice and Data1998Inngår i: 3rd International Symposium on Multi Dimensional Mobile Communications (MDMC'98), Menlo Park, CA, September 21, 1998, 1998Konferansepaper (Fagfellevurdert)
  • 24.
    Xu, Youshi
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Nilsson, Peter
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Wiklund, Håkan
    On the utilization of voice-unused resource for data transmission in PRMA systems1998Inngår i: IEEE 1998 International Conference on Universal Personal Communications, Florence, It., Oct 05-09, 1998. ICUPC '98. Vol. 2, IEEE , 1998, s. 1043-1047Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In the paper voice-unused resource in a voice-only PRMA system is analyzed. A mechanism for the detection of voice-unused resource is proposed. How to use the voice-unused resource for data transmission is proposed. Therefore, the voice subsystem is totally a voice-only PRMA system, and the existence of data transmission just improves the channel utilization efficiency, without any influence on the performance of voice communications. Simulation results show that a significant amount of data traffic can be supported by the voice-unused resource.

  • 25.
    Xu, Youshi
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Zhang, Tingting
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    A VLSI Design for Universal Reed-Solomon Erasure Decoder2002Inngår i: International Conference on Signal Processing Proceedings, ICSP, IEEE conference proceedings, 2002, s. 398-401, artikkel-id 1181074Konferansepaper (Fagfellevurdert)
  • 26.
    Xu, Youshi
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Zhang, Tingting
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    An implementation of coding scheme for packet loss protection2001Inngår i: Proceedings of the 11th International Packet Video Workshop, 2001Konferansepaper (Annet vitenskapelig)
  • 27.
    Xu, Youshi
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Zhang, Tingting
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Variable shortened-and-punctured Reed-Solomon codes for packet loss protection2002Inngår i: IEEE Transactions On Broadcasting, ISSN 0018-9316, Vol. 48, nr 3, s. 237-245Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, techniques of Reed-Solomon (RS) codes to recover lost packets in digital video/audio broadcasting and packet switched network communications are reviewed. Usually, different RS codes and their corresponding encoders/decoders are designed and utilized to meet different requirements for different systems and applications. We incorporate these techniques into a variable RS code and present an encoding and decoding algorithm suitable for the variable RS code. A mother RS code can be used to produce a variety of RS codes and the same encoder/decoder can be used for all the derivative codes with adding/detecting zeros, removing a part of parity symbols, and adding erasures. A VLSI implementation for erasure decoding of the proposed variable RS code is described and the achievable performance is quantitatively analyzed. A typical example shows that the signal processing speed is up to 2.5 Gbits/second and the processing delay is less than one millisecond, when integrating the decoder on a single chip. Therefore, the proposed algorithm and the encoder/decoder can universally be utilized for different applications with various requirements, such as transmission data rate, packet length, packet loss protection capacity, as well as layered protection and adaptive redundancy protection in DVB/DAB broadcasting, Internet and mobile Internet communications.

  • 28.
    Xu, Youzhi
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Zhang, Tingting
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    An adaptive redundancy technique for wireless indoor multicasting2000Inngår i: IEEE Symposium on Computers and Communications - Proceedings, Los Alamitos, Calif: IEEE Computer Society , 2000, s. 607-614Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper we present an adaptive technique that combines forward error correction (FEC) with channel state estimation (CSE) and automatic repeat request (ARQ) for packet loss recovery in wireless indoor multicast systems. The novel aspect of the technique is its ability to achieve significant packet throughput with high data reliability, to avoid feedback acknowledgement (ACK) implosion, as well as to reduce and flexibly to limit delay for real-time applications. We suggest a set of criteria to measure the multicast performance and simulate a simple two-state indoor channel model. The simulation results show that the proposed technique significantly improves the communication quality and channel efficiency, to compare with traditional FEC and ARQ techniques.

  • 29.
    Xue, Shang
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Xu, Youzhi
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Oelmann, Bengt
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Hybrid Golomb codes for a group of quantised GG sources2003Inngår i: IEE Proceedings - Vision Image and Signal Processing, ISSN 1350-245X, E-ISSN 1359-7108, Vol. 150, nr 4, s. 256-260Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The authors develop a class of codes for quantised generalised Gaussian (GG) sources. This new class of codes, that are called hybrid Golomb (HG) codes, are hybrids of Golomb-Rice (GR) codes and exp-Golomb (EG) codes. They integrate the properties of both GR and EG codes, which makes their performance more robust under variable source parameters. The efficiencies of the three classes of codes are compared and it is shown that the set of HG codes have efficiencies of approximately 70% or greater for a wide range of parameter values, whereas GR and EG codes can have efficiencies lower than 20%. The efficiencies of the set of HG codes are also compared with the set of EG codes that have the best performance under parameter scaling. It is shown that. this set of HG codes still achieve a higher efficiency.

  • 30.
    Yan, Hairong
    et al.
    Jönköping University.
    Huo, Hongwei
    Beijing Jiatong University.
    Xu, Youzhi
    Jönköping University.
    Gidlund, Mikael
    ABB Corporate Research.
    Wireless Sensor Network based e-health system - implementation and experimental results2010Inngår i: IEEE transactions on consumer electronics, ISSN 0098-3063, E-ISSN 1558-4127, Vol. 56, nr 4, s. 2288-2296Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    With the increasing number senior citizens, E-health is targeted for home use with the special requirements of being usable in everyday life and low cost. A wireless sensor network application is proposed here for 24 hour constant monitoring without disturbing daily activities of elderly people and their caretakers. In the system proposed, both fixed and body (mobile) sensors are used. Since not every elder likes to have a sensor board attached to him/her, and in many cases, he/she may not carry the sensor; the home sensor network independently would have the ability to monitor the health status and living environment based on the multisensor data analysis and fusion. A mixed positioning algorithm is proposed to determine where the elderly person is. The purpose of the positioning is to help the system to determine the person's activities and further to make decisions about his/her health status. The system could take care of two types of the basic needs of an elderly person: everyday needs as abnormal events and emergency alarms to doctors and caretakers through telephone, SMS and e-mail, and day to day requirements such as taking of medicine, having lunch, turn off the microwave oven, and so on. At same time, the system is sensitive to security and privacy issues.

  • 31.
    Yang, D
    et al.
    Beijing Jiatong University, PR China.
    Gidlund, Mikael
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för informations- och kommunikationssystem. ABB Corporate Research.
    Shen, Wei
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för informations- och kommunikationssystem.
    Xu, Youzhi
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för informations- och kommunikationssystem.
    Zhang, Tingting
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för informations- och kommunikationssystem.
    Zhang, Honke
    Beijing Jiatong University, PR China.
    CCA-Embedded TDMA Enabling Acyclic Traffic in Industrial Wireless Sensor Networks2013Inngår i: Ad hoc networks, ISSN 1570-8705, E-ISSN 1570-8713, Vol. 11, nr 3, s. 1105-1121Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A growing trend in the automation industry is to use wireless technologies to reduce cable costs and deployment time, unlock stranded information in deployed devices and enable wireless control applications. The WirelessHART protocol is the first open and interoperable industrial wireless sensor network standard, which proposes a combination of time division multiple access (TDMA) and channel hopping as a medium access control (MAC) protocol. TDMA is a schedule-based protocol, which is suitable for predictable cyclic traffic. However, for burst acyclic traffic, TDMA degenerates into an inefficient slotted ALOHA. In this article, we propose a complementary mechanism to TDMA, CCA-Embedded TDMA, which can be applied to improve the transmission efficiency and system stability of TDMA-based systems such as the WirelessHART protocol. A Markov model is proposed to evaluate the efficiency of system throughput and expected delay of CCA-Embedded TDMA. Furthermore, we show by analytical and simulation results that our proposed CCA-Embedded TDMA scheme can increase the throughput by 100% and reduce the expected delay by 75% for a common scenario. We also implement CCA-Embedded TDMA into an embedded system as a part of the WirelessHART MAC protocol. The experimental results verify the efficiency of CCA-Embedded TDMA and its backward compatibility with the WirelessHART protocol.

  • 32.
    Yang, Dong
    et al.
    Beijing Jiatong University.
    Gidlund, Mikael
    ABB Corporate Research.
    Xu, Youzhi
    Jönköping University.
    Performance Analysis on a New MAC DT-CSMA2011Inngår i: IECON 2011 - 37th Annual Conference on IEEE Industrial Electronics Society, IEEE conference proceedings, 2011, s. 3522-3527Konferansepaper (Fagfellevurdert)
    Abstract [en]

    TDMA has been resumed for industrial wireless sensor network (IWSN) like WirelessHART and ISA 100.11a recently, because TDMA is suitable for periodic traffic which is predictable to pre-assign. However, for random traffic TDMA degenerates to inefficient slotted ALOHA. In our previous work, we propose a new medium access control (MAC) scheme called discrete-time CSMA (DT-CSMA) that can be applied to improve the efficiency of TDMA-based system that transmits periodic and random traffic. In this paper, we give a model to evaluate system throughput for DT-CSMA. An analysis of typical scenario shows DT-CSMA improves the throughput by 100%. We also build a model to evaluate synchronization influence on DT-CSMA, which indicates that the influence is limited.

  • 33.
    Yang, Dong
    et al.
    Beijing Jiatong University, China.
    Ma, Jian
    Beijing Jiatong Univeristy, China.
    Xu, Youzhi
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för informationssystem och -teknologi.
    Gidlund, Mikael
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för informationssystem och -teknologi.
    Safe-WirelessHART: A Novel Framework Enabling Safety-Critical Applications Over Industrial WSNs2018Inngår i: IEEE Transactions on Industrial Informatics, ISSN 1551-3203, E-ISSN 1941-0050, Vol. 14, nr 8, s. 3513-3523Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Industrial wireless sensor networks (IWSNs) have mainly been used to monitor applications, but recently an interest in control and safety applications has emerged. Functional safety and communication in open transmission systems have been laid down in the IEC 61784-3-3 standard. The standard is based on a cyclic polling mechanism, which consumes a considerable amount of bandwidth; since existing IWSNs are very resource-constrained, this becomes a major challenge. To overcome this problem, this paper proposes a novel framework that uses an event-triggered failsafe mechanism based on synchronous wired polling and wireless time-slotted time division multiple access. We analytically derive the minimum and maximum bound for the most important metric for safety-critical applications, safety function response time (SFRT). A new metric, normal state interrupt time (NSIT), is proposed in this paper. Furthermore, we also implement the proposed framework by using the WirelessHART standard. The results are compared to the classical time-triggered approach used in the IEC 61784-3-3 standard. The obtained results show that the proposed framework can reduce the bandwidth usage by 90% and support safety-critical applications that require a SFRT less or equal to 150 ms.

  • 34.
    Yang, Dong
    et al.
    Beijing Jiaotong University, Beijing, China .
    Wang, Haochang
    Beijing Jiaotong University, Beijing, China .
    Zheng, Tao
    Beijing Jiaotong University, Beijing, China .
    Gidlund, Mikael
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för informations- och kommunikationssystem. ABB AB, Corporate Research, Västerås, Sweden.
    Xu, Youzhi
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för informations- och kommunikationssystem.
    Zhang, Honke
    Beijing Jiaotong University, Beijing, China .
    Applying Industrial Wireless Sensor Networks to Welder Machine System2014Inngår i: IPSN 2014 - Proceedings of the 13th International Symposium on Information Processing in Sensor Networks (Part of CPS Week), 2014, s. Art. no. 6835794-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Despite lots of research efforts in the area of Industrial Wireless Sensor Networks (IWSNs), there is a lack of really practical IWSN implementations, deployments and in-field experiments. This demo presents the design and implementation of an IWSN for welder machine systems based on the first IWSN standard WirelessHART. The goal of this work is to find the problems and challenges from IWSN standard to implementation, and motivate other designers to explore more IWSN applications.

  • 35.
    Yang, Dong
    et al.
    Beijing Jiatong University.
    Xu, Youzhi
    Jönköping University.
    Gidlund, Mikael
    ABB Corporate Research.
    Wireless Coexistence between IEEE 802.11 and IEEE 802.15.4-based Networks: A Survey2011Inngår i: International Journal of Distributed Sensor Networks, ISSN 1550-1329, E-ISSN 1550-1477Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    As more and more wireless devices use the 2.4 GHz radio spectrum, the coexistence of 2.4 GHz wireless devices operating in one place has become a hot topic. With low transmit power, the widely deployed IEEE 802.15.4-based networks are easily interfered with by other 2.4 GHz wireless networks, such as IEEE 802.11. IEEE 802.15.4-based wireless networks have paid great attention to the coexistence between themselves and with other non-IEEE 802.15.4 wireless networks. This problem has been further promoted by two new industry wireless standards, WirelessHART and ISA100, to meet special industry requirements. This paper surveys the studies on the coexistence between IEEE 802.11 and IEEE 802.15.4-based networks following the general analysis method of “question-analysis-solution.” Based on the survey study, we discuss about some open research issues and developments in this field.

  • 36.
    Yang, Dong
    et al.
    Beijing Jiaotong Univ, Beijing 100044, Peoples R China.
    Xu, Youzhi
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för informations- och kommunikationssystem.
    Wang, Hongchao
    Beijing Jiaotong Univ, Beijing 100044, Peoples R China.
    Zheng, Tao
    Beijing Jiaotong Univ, Beijing 100044, Peoples R China.
    Zhang, Hao
    Beijing Jiaotong Univ, Beijing 100044, Peoples R China.
    Zhang, Hongke
    Beijing Jiaotong Univ, Beijing 100044, Peoples R China.
    Gidlund, Mikael
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för informations- och kommunikationssystem.
    Assignment of Segmented Slots Enabling Reliable Real-Time Transmission in Industrial Wireless Sensor Networks2015Inngår i: IEEE transactions on industrial electronics (1982. Print), ISSN 0278-0046, E-ISSN 1557-9948, Vol. 62, nr 6, s. 3966-3977Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Industrial wireless sensor networks (IWSNs) have the potential to contribute significantly in areas such as cable replacement, mobility, flexibility, and cost reduction. Nevertheless, the industrial environment that the IWSNs operate in is very challenging because of dust, heat, water, electromagnetic interference, and interference from other wireless devices, which make it difficult for current IWSNs to guarantee reliable real-time communication. In this paper, we present a novel method based on the segmented slot assignment, fast slot competition, and free node concept that will improve the reliability and real-time communication significantly so that more advanced applications can be enabled. The main purpose of the algorithms is to improve the retransmission efficiency for time-division-multiple-access-based multihop IWSNs by using limited shared slot resources more efficiently. More importantly, the proposed algorithms support efficient slot rescheduling caused by link or node failure. We evaluate the proposed methods by using simulations and a real implementation targeting monitoring of welder machines. Our obtained results show that the proposed method outperforms the first published and most widely used IWSN standard called WirelessHART.

  • 37.
    Zhang, Tingting
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Jennehag, Ulf
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Xu, Youshi
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Numerical modeling of transmission errors and video quality of MPEG-22001Inngår i: Signal processing. Image communication, ISSN 0923-5965, E-ISSN 1879-2677, Vol. 16, nr 8, s. 817-825Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 38.
    Zhang, Tingting
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Jennehag, Ulf
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Xu, Youzhi
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Numerical modeling of transmission errors and video quality of MPEG-22000Inngår i: Packet Video 2000: Proceedings. 10th International Packet Video Workshop, Cagliari, Sardinia, Italy, May 1-2 2000, 2000Konferansepaper (Annet vitenskapelig)
  • 39.
    Zhang, Tingting
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Xu, Youshi
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Unequal Packet Loss Protection for Layered Video Transmission1999Inngår i: IEEE Transaction on Broadcasting, ISSN 0018-9316, Vol. 45, nr 2, s. 243-252Artikkel i tidsskrift (Fagfellevurdert)
  • 40.
    Zhang, Tingting
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Xu, Youzhi
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    General Modeling of Layered Packet Video for Multicast Systems1999Inngår i: Proceedings of the third World Multiconference on Systemics, Cybernetics and Informatics (SCI'99) and the Fifth International Conference on Information Systems Analysis and Synthesis (ISAS'99), Orlando, USA, July 31 August 4, 1999, 1999, s. 261-268Konferansepaper (Annet vitenskapelig)
  • 41.
    Zhang, Tingting
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Österberg, Patrik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Xu, Youzhi
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Multicast-Favorable Max-Min Fairness: a general definition of multicast fairness2005Inngår i: Proceedings - First International Conference on Distributed Frameworks for Multimedia Applications 2005, DFMA '05, IEEE Computer Society, 2005, s. 239-244, artikkel-id 1385208Konferansepaper (Fagfellevurdert)
    Abstract [en]

    As video-streaming services are becoming more common the benefit of multicast transmission is growing, because multicast is more bandwidth efficient than unicast in scenarios where many receivers simultaneously are interested in the same data. Of the same reason the concept of multicast fairness is starting to attract attention, it might be sensible to give multicast flows higher priority and thereby create an incentive for the use of multicast transmission. Allocating link bandwidth in proportion to the logarithm of the number of receivers of a flow, which favors multicast flows without totally starving unicast flows, has been proposed in [1]. That was however just as a bandwidth-allocation policy ran on the individual routers and not a definition of multicast fairness. To our knowledge no one has yet come up with a definition of multicast fairness which prioritizes multicast flows. In this paper we present a general multicast-fairness definition, named multicast-favorable max-min fairness (MFMF), which can be used together with any multicast-favorable function.

1 - 41 of 41
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