2015/4

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    Video Tracking for Visual Degraded Aerial Vehicle with H-PMHT
    (Společnost pro radioelektronické inženýrství, 2015-12) Pakfiliz, Ahmet G.
    The work presented in this paper describes a novel approach for automatic video tracking of visual degraded air vehicles in daylight with sky background. The offered and applied video object tracking method is based on Histogram Probabilistic Multi Hypothesis Tracker algorithm. The H-PMHT is an expectation maximization based algorithm developed for tracking objects in intense clutter environment by using intensity modulated data streams. Basically H-PMHT algorithm is suitable for linear-Gaussian point spread function case. However, recent studies have indicated that the algorithm is also applicable for non-linear and non-Gaussian target shapes. Thus H-PMHT becomes a suitable alternative for tracking applications with sonar, high resolution radars,IR, UV sensors and cameras. In this work H-PMHT algorithm is used for video tracking of visual degraded air vehicles. For this purpose RGB video data is processed by using a reciprocal pixel intensity measurement for meeting the requirements of the tracking process. A simulation study is conducted in order to demonstrate the video tracking performance of H-PMHT against visual degraded air vehicles. Also the results obtained with H-PMHT algorithm are compared with the results of amplitude information added Interacting Multi Model Probabilistic Data Association algorithm.
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    Multi-Core DSP Based Parallel Architecture for FMCW SAR Real-Time Imaging
    (Společnost pro radioelektronické inženýrství, 2015-12) Gu, Chengfei; Chang, Wenge; Li, Xiangyang; Liu, Zhaohe
    This paper presents an efficient parallel processing architecture using multi-core Digital Signal Processor (DSP) to improve the capability of real-time imaging for Frequency Modulated Continuous Wave Synthetic Aperture Radar (FMCW SAR). With the application of the proposed processing architecture, the imaging algorithm is modularized, and each module is efficiently realized by the proposed processing architecture. In each module, the data processing of different cores is executed in parallel, also the data transmission and data processing of each core are synchronously carried out, so that the processing time for SAR imaging is reduced significantly. Specifically, the time of corner turning operation, which is very time-consuming, is ignored under computationally intensive case. The proposed parallel architecture is applied to a compact Ku-band FMCW SAR prototype to achieve real-time imageries with 34 cm x 51 cm (range x azimuth) resolution.
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    Cascade Structure of Digital Predistorter for Power Amplifier Linearization
    (Společnost pro radioelektronické inženýrství, 2015-12) Solovyeva, Elena B.
    In this paper, a cascade structure of nonlinear digital predistorter (DPD) synthesized by the direct learning adaptive algorithm is represented. DPD is used for linearization of power amplifier (PA) characteristic, namely for compensation of PA nonlinear distortion. Blocks of the cascade DPD are described by different models: the functional link artificial neural network (FLANN), the polynomial perceptron network (PPN) and the radially pruned Volterra model (RPVM). At synthesis of the cascade DPD there is possibility to overcome the ill conditionality problem due to reducing the dimension of DPD nonlinear operator approximation. Results of compensating nonlinear distortion in Wiener–Hammerstein model of PA at the GSM–signal with four carriers are shown. The highest accuracy of PA linearization is produced by the cascade DPD containing PPN and RPVM.
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    Cross-Layer Combining of Adaptive Modulation and Truncated ARQ in Multichannel Beamforming MIMO Systems
    (Společnost pro radioelektronické inženýrství, 2015-12) Ivanis, Predrag; Drajic, Dejan; Brkic, Srdan
    In this study the authors provide a cross-layer design of multiple-input-multiple-output (MIMO) systems, with the aim to maximize spectral efficiency. We consider MIMO systems based on a multichannel beamforming technique that combines an adaptive modulation and truncated automatic repeat request procedures, for the case of Rayleigh fading propagation and imperfect channel state information. Closed-form expressions for the average spectral efficiency and the packet loss rate are derived for arbitrary eigenchannel of multichannel beamforming systems, with any number of receiving and transmitting antennas. An analytical expression for the average time during which a particular constellation is used continuously, is also derived. We propose the method based on the optimization of the target packet error rate and the maximum number of retransmissions that outperforms the existing cross-layer combining procedures. Furthermore, we develop the numerical algorithm for optimization of the eigenchannel power allocation. The proposed cross-layer design results in higher average spectral efficiency, reduced maximum delay and increased energy efficiency. The analytical results are validated by Monte Carlo simulation.
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    Energy Efficient Power Allocation for Distributed Antenna System over Shadowed Nakagami Fading Channel
    (Společnost pro radioelektronické inženýrství, 2015-12) Wang, Ying; Yu, Xiangbin; Li, Yang; Wu, Binbin
    In this paper, the energy efficiency (EE) of downlink distributed antenna system (DAS) with multiple receive antennas is investigated over composite fading channel that takes the path loss, shadow fading and Nakagami-m fading into account. Our aim is to maximize EE which is defined as the ratio of the transmission rate to the total consumed power under the constraints of maximum transmit power of each remote antenna. According to the definition of EE and using the upper bound of average EE, the optimized objective function is provided. Based on this, utilizing Karush-Kuhn-Tucker (KKT) conditions and mathematical derivation, a suboptimal energy efficient power allocation (PA) scheme is developed, and closed-form PA coefficients are obtained. The developed scheme has the EE performance close to the existing optimal scheme. Moreover, it has relatively lower complexity than the existing scheme because only the statistic channel information and less iteration are required. Besides, it includes the scheme in composite Rayleigh channel as a special case. Simulation results show the effectiveness of the developed scheme.