2012/2

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    Watermarking FPGA Bitfile for Intellectual Property Protection
    (Společnost pro radioelektronické inženýrství, 2012-06) Zhang, Jiliang; Lin, Yaping; Wu, Qiang; Che, Wenjie
    Intellectual property protection (IPP) of hardware designs is the most important requirement for many Field Programmable Gate Array (FPGA) intellectual property (IP) vendors. Digital watermarking has become an innovative technology for IPP in recent years. Existing watermarking techniques have successfully embedded watermark into IP cores. However, many of these techniques share two specific weaknesses: 1) They have extra overhead, and are likely to degrade performance of design; 2) vulnerability to removing attacks. We propose a novel watermarking technique to watermark FPGA bitfile for addressing these weaknesses. Experimental results and analysis show that the proposed technique incurs zero overhead and it is robust against removing attacks.
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    Downlink Video Streaming for Users Non-Equidistant from Base Station
    (Společnost pro radioelektronické inženýrství, 2012-06) Pejoski, Slavche; Kafedziski, Venceslav
    We consider multiuser video transmission for users that are non-equidistantly positioned from base station. We propose a greedy algorithm for video streaming in a wireless system with capacity achieving channel coding, that implements the cross-layer principle by partially separating the physical and the application layer. In such a system the parameters at the physical layer are dependent on the packet length and the conditions in the wireless channel and the parameters at the application layer are dependent on the reduction of the expected distortion assuming no packet errors in the system. We also address the fairness in the multiuser video system with non-equidistantly positioned users. Our fairness algorithm is based on modified opportunistic round robin scheduling. We evaluate the performance of the proposed algorithms by simulating the transmission of H.264/AVC video signals in a TDMA wireless system.
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    A novel JPEG steganography method based on modulus function with histogram analysis
    (Společnost pro radioelektronické inženýrství, 2012-06) Banoci, Vladimir; Bugar, Gabriel; Levicky, Dusan; Klenovicova, Zita
    In this paper, we present a novel steganographic method for embedding of secret data in still grayscale JPEG image. In order to provide large capacity of the proposed method while maintaining good visual quality of stego-image, the embedding process is performed in quantized transform coefficients of Discrete Cosine transform (DCT) by modifying coefficients according to modulo function, what gives to the steganography system blind extraction predisposition. After-embedding histogram of proposed Modulo Histogram Fitting (MHF) method is analyzed to secure steganography system against steganalysis attacks. In addition, AES ciphering was implemented to increase security and improve histogram after-embedding characteristics of proposed steganography system as experimental results show.
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    Third-order Intermodulation Reduction in Mobile Power Amplifiers by the First Stage Bias Control
    (Společnost pro radioelektronické inženýrství, 2012-06) Jung, Jonghun; Kwak, Cholho; Lee, Jongsoo
    In this paper, the third order intermodulation distortion (IMD3) of three-stage power amplifier (PA) is analyzed using the Volterra series. The analysis explains how the total IMD3 of the three-stage power amplifier can be reduced by the first-stage bias condition. The three-stage PA, which is fabricated using InGaP/GaAs hetero-junction bipolar transistor (HBT), operates with an optimized first driver stage bias for higher P1dB and good gain flatness. The power amplifier has been designed for 1626.5 MHz~1660.5 MHz satellite mobile communications. With π/4 DQPSK modulation signals, this PA can deliver a highly linear output power of 33 dBm from 3.6V supply voltage. At 33 dBm output power, it shows a gain of 31.9 dB, a power-added efficiency (PAE) of 39.8%, an adjacent channel power ratio (ACPR) of -28.2 dBc at a 31.25 KHz offset frequency.
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    A Modified Bipolar Translinear Cell with Improved Linear Range and Its Applications
    (Společnost pro radioelektronické inženýrství, 2012-06) Merz, Naruemol; Kiranon, Wiwat; Wongtachathum, Chariya; Pawarangkoon, Prajuab; Narksarp, Wipavan
    This paper presents a technique to extend the linear input voltage range of a sinh mixed translinear cell proposed by Fabre [1]. This technique extends the linear operation range of the circuit by inserting common-anode-connected pairs into the mixed translinear cell. Then the relationship between the output current and the input voltage is developed to be linear. The transconductance gain can be adjusted electronically while keeping its linearity. The performance of the proposed circuit is verified by mathematical analysis and by SPICE simulations. Finally, applications of the proposed cell in a floating resistor and a CCCII for designing an instrumentation amplifier are presented.