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  • 1.
    Jansson, Henrik
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Kozica, Eermin
    Scania CV.
    Sahlholm, Per
    Scania CV.
    Johansson, Karl Henrik
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Improved road grade estimation using sensor fusion2006Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A method for estimation of the road grade basedon standard mounted sensors in a heavy duty vehicle ispresented. The method combines information from a barometerand a GPS with velocity and torque measurements of conventionaltype. The sensor information is adaptively integratedusing extended Kalman filtering. This provides a systematicmethod for dealing with varying uncertainty in the sensors.The method can handle periods of missing or unreliable datafrom one or several sensors, e.g., occasions when the satellitecoverage is low or when the brakes are applied.

  • 2.
    Kozica, Ermin
    KTH, Skolan för elektro- och systemteknik (EES), Ljud- och bildbehandling.
    Paradigms for Real-Time Video Communication and for Video Distribution2011Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The use of new information technologies has drastically changed the way that we lead our lives. Communication technologies in particular have had a great impact on our day-to-day behavior. For example, it is now common to hear the voice and see the face of our loved-ones on another continents, or work with colleagues across the globe on a daily basis. With this change in behavior and the fast adoption of emerging technologies, new challenges in the telecommunications area are arising. This thesis is concerned with two such challenges: real-time video communication and video distribution.

    The latency constraint in real-time video communication is in essence incompatible with the uncertainty of best-effort networks, such as the Internet. The recent arrival of smart-phones has added another requirement to the application, in terms of the limited computational and battery power. The research community has invested a large amount of effort in developing techniques that allow a mobile sender to outsource video encoding complexity to an unconstrained receiver by means of a feedback channel. We question that approach with respect to real-time applications, arguing that long round-trip-times may render any feedback unusable at best, and costly in practice. We investigate the effect of channel round-trip-times on the popular distributed video coding setup, as well as on the traditional hybrid video coding architecture. Using a simple analytical framework, we propose the use of systems that adapt to the video content and the network in real- time. Our results show that substantial improvements in video quality can be achieved when the feedback channel is used correctly.

    The use of mobile devices has also a significant impact on the application of video distribution. In general, the multitude of devices that can be used to download and view video places new requirements on video distribution systems. The system must not only be able to scale to a large number of receivers in a bandwidth efficient manner, it must also support a wide range of network capacities and display capabilities. We address this problem by optimizing the set of rates that is used to provide video to receivers with heterogeneous requirements. Our approach is based on a favorable interpretation of the underlying mathematical problem, allowing the use of well-known quantization theoretic concepts. The resulting solution provides the possibility to design video distribution systems that adapt to changes in receiver characteristics online, with minimal delay.

  • 3.
    Kozica, Ermin
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Ljud- och bildbehandling.
    Kleijn, W. Bastiaan
    KTH, Skolan för elektro- och systemteknik (EES), Ljud- och bildbehandling.
    A Quantization Theoretic Perspective on Simulcast and Layered Multicast Optimization2012Inngår i: IEEE/ACM Transactions on Networking, ISSN 1063-6692, E-ISSN 1558-2566, Vol. 20, nr 2, s. 585-593Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We consider rate optimization in multicast systems that use several multicast trees on a communication network. The network is shared between different applications. For that reason, we model the available bandwidth for multicast as stochastic. For specific network topologies, we show that the multicast rate optimization problem is equivalent to the optimization of scalar quantization. We use results from rate-distortion theory to provide a bound on the achievable performance for the multicast rate optimization problem. A large number of receivers makes the possibility of adaptation to changing network conditions desirable in a practical system. To this end, we derive an analytical solution to the problem that is asymptotically optimal in the number of multicast trees. We derive local optimality conditions, which we use to describe a general class of iterative algorithms that give locally optimal solutions to the problem. Simulation results are provided for the multicast of an i.i.d. Gaussian process, an i.i.d. Laplacian process, and a video source.

  • 4.
    Kozica, Ermin
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Ljud- och bildbehandling (Stängd 130101).
    Kleijn, W. Bastiaan
    KTH, Skolan för elektro- och systemteknik (EES), Ljud- och bildbehandling (Stängd 130101).
    Analytical rate optimization for multicast2008Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We consider the problem of multicast rate optimization for a given number of multicast groups. The efficient solution of this problem is particularly relevant for video multicast. Motivated by practical considerations, such as the need for adaptivity to changing network conditions, we develop an analytical solution that minimizes the expected distortion of a receiver. Unlike previous work, we recognize variability in existing networks and model the receiver reception capacities by a continuous stochastic variable. Our analytical solution is optimal under the assumption of a large number of multicast groups. We investigate the distortion overhead when this assumption is not satisfied and find that it is low. We compare our results to the state of the art, iterative optimization for a realization of receiver reception capacities, and find that our analytical solution performs better for any number of multicast groups. copyright by EURASIP.

  • 5.
    Kozica, Ermin
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre. KTH, Skolan för elektro- och systemteknik (EES), Ljud- och bildbehandling.
    Kleijn, W. Bastiaan
    KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre. KTH, Skolan för elektro- och systemteknik (EES), Ljud- och bildbehandling.
    Joint optimization of the redundancy of multiple-description coders for multicast2009Inngår i: 2009 IEEE INTERNATIONAL CONFERENCE ON ACOUSTICS, SPEECH, AND SIGNAL PROCESSING, 2009, s. 2481-2484Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We consider the optimization of multicast over packet-switched communication networks with a non-zero packet-loss probability. For the system setup consisting of a number of multiple-description coders, we jointly optimize these coders. We propose an analytic solution, asymptotically optimal in the number of multiple-description coders. The analytic solution allows for fast system adaptation to changing network conditions. A locally optimal optimization algorithm that is useful when the number of multicast groups is small is derived. Simulations show that the utilization of the analytic solution incurs a low overhead on the performance when compared to the locally optimal solution, even for a small number of multiple-description coders.

  • 6.
    Kozica, Ermin
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Ljud- och bildbehandling.
    Kleijn, W. Bastiaan
    KTH, Skolan för elektro- och systemteknik (EES), Ljud- och bildbehandling.
    On Bandwidth-Efficient Video Distribution Through Multi-Rate Video Encoding2011Inngår i: IEEE transactions on multimedia, ISSN 1520-9210, E-ISSN 1941-0077Artikkel i tidsskrift (Annet vitenskapelig)
  • 7.
    Kozica, Ermin
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Ramchandran, Kannan
    Kleijn, W. Bastiaan
    KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    COMPLEXITY-OUTSOURCED LOW-LATENCY VIDEO ENCODING THROUGH FEEDBACK UNDER A SUM-RATE CONSTRAINT2010Inngår i: 2010 IEEE INTERNATIONAL CONFERENCE ON IMAGE PROCESSING , 2010, s. 973-976Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In live video communication, the quality of the video that is encoded on a mobile device is more often than not constrained by the available computational resources. We address this problem by allowing the encoder to "outsource" the encoding complexity to the decoder through the use of feedback, under a sum-rate constraint comprising the weighted sum of the forward and feedback rates. Analysis of such a complexity-outsourced framework using an analytically tractable video model reveals that the feedback rate should be optimally adapted to the video motion characteristics. Application of our framework to real-world video sequences reveals the efficacy of our proposed architecture, with experimental results validating that substantial gains in PSNR are achievable over state-of-the-art fast-search algorithms at a comparable level of complexity. These gains are significant even for mobile live video communication applications over the Internet.

  • 8.
    Kozica, Ermin
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Ljud- och bildbehandling.
    Ramchandran, Kannan
    University of California, Berkeley.
    Kleijn, W. Bastiaan
    KTH, Skolan för elektro- och systemteknik (EES), Ljud- och bildbehandling.
    Power-Constrained Low-Latency Video Encoding using Feedback2010Inngår i: IEEE transactions on circuits and systems for video technology (Print), ISSN 1051-8215, E-ISSN 1558-2205Artikkel i tidsskrift (Annet vitenskapelig)
  • 9.
    Kozica, Ermin
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Ljud- och bildbehandling (Stängd 130101).
    Zachariah, Dave
    KTH, Skolan för elektro- och systemteknik (EES), Ljud- och bildbehandling (Stängd 130101).
    Kleijn, W. Bastiaan
    KTH, Skolan för elektro- och systemteknik (EES), Ljud- och bildbehandling (Stängd 130101).
    Interlacing intraframes in multiple-description video coding2007Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We introduce a method to improve performance of multiple-description coding based on legacy video coders with pre- and postprocessing. The pre- and post-processing setup is general, making the method applicable to most legacy coders. For the case of two coders, a relative displacement of the intra-coding mode between the coders is shown to give improved robustness to packet loss. The optimal displacement of the intra-coding mode is found analytically, using a distortion minimization formulation where two independent Gilbert channels are assumed. The analytical results are confirmed by simulations. Tests with an H.263 coder show significant improvement in YPSNR over equivalent systems with no relative displacement of the intra-coding operation.

  • 10.
    Kozica, Ermin
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Ljud- och bildbehandling.
    Zhang, Hao
    University of California, Berkeley.
    Ramchandran, Kannan
    University of California, Berkeley.
    Frame-Bufferless Sum-Rate Constrained Video Encoding using Feedback2010Inngår i: IEEE International Conference on Image Processing, 2010, s. 797-800Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We investigate the design of a frame-bufferless and low-latency videocommunication system, where the encoder has no access to any previous frames and only one use of feedback communication from the decoder to the encoder is allowed in encoding each frame. This strict requirement on encoder complexity and system latency is of critical importance in designing low complexity realtime video communication systems, where the encoder is limited in storage and computing resources and the use of the feedback channel must not incur accumulated receiver playback delay. We propose a simple online statistical model that captures the time-varying video process and develop a general framework that explores how to best utilize the feedback and distributed source coding mechanisms to minimize the overall communicationrate. Our analysis and experimental results validate the efficiency of the proposed system and highlight its potential in practical system design.

  • 11.
    Sahlholm, Per
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Jansson, H.
    Kozica, Ermin
    Johansson, Karl Henrik
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    A sensor and data fusion algorithm for road grade estimation2007Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Emerging driver assistance systems, such as look-ahead cruise controllers for heavy duty vehicles, require high precision digital maps. This contribution presents a road grade estimation algorithm for fusion of GPS and vehicle real-time sensor data, with measurements from previous runs over the same road segment. The resulting road grade estimate is thus enhanced using measurements from additional traversals of known roads. Distributed data fusion is utilized to ensure that the storage requirement of known roads does not increase when additional measurements are processed. The implemented algorithm, which is based on extended Kalman filtering and smoothing, is described in detail. Experiments on a Scania test vehicle show the advantages and some of the challenges with the proposed approach.

  • 12.
    Zhong, Jianghua
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Hu, Xiaoming
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Kleijn, W. Bastiaan
    KTH, Skolan för elektro- och systemteknik (EES), Ljud- och bildbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Kozica, Ermin
    KTH, Skolan för elektro- och systemteknik (EES), Ljud- och bildbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Constructive camera pose control for optimizing multiview distributed video coding2008Inngår i: Proceedings of the IEEE Conference on Decision and Control, 2008, s. 3372-3379Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper camera pose control for optimizing multiview distributed video coding is considered. The scenario considered is that multiple agents with monocular cameras observe a common scene in a three dimensional world. To get a good video reconstruction under a transmission rate constraint, the camera closest to the center of the camera array is chosen as the reference camera. The poses of all other cameras are controlled and designed such that their images are maximally similar under a constraint on their separation. Based on the rigid motion allowed for the cameras, two cases are considered. For the case where the rigid motion only involves translation, translation control is designed. For the case where it involves both translation and rotation, both controls are constructed. Some simulated results are given to show the efficiency of the designed controllers.

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