Recent Submissions

Now showing 1 - 5 of 25
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    Software and Hardware Solutions for Channel Estimation based on Cyclic Golay Sequences
    (Společnost pro radioelektronické inženýrství, 2016-12) Csuka, Barna; Kollar, Zsolt
    This paper presents channel estimation methods based on cyclic complementary Golay sequences. First, the conventional Golay correlator is investigated, then a frequency domain approach using Discrete Fourier Transform (DFT) is provided. A complex valued fast Golay correlator is introduced which can be used for the estimation of complex valued channel impulse response. Furthermore, this paper presents the Recursive DFT (R-DFT), a signal processing architecture which may be beneficial compared to the well-known Fast Fourier Transform (FFT). The R-DFT is able to efficiently calculate a point-by-point block spectra of the input signal, which makes it suitable for hardware implementation. Throughout the paper, the R-DFT is applied and it is compared to the conventional estimation methods. Finally, the efficiency of the proposed schemes is compared through simulations based on the 60 GHz WiGig and the COST 207 standard, applying various channel models.
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    Improving 3D-Turbo Code's BER Performance with a BICM System over Rayleigh Fading Channel
    (Společnost pro radioelektronické inženýrství, 2016-12) Yao, Rugui; Zhu, Yongjia; Xu, Juan; Gao, Fangqi; Wang, Ling
    Classical Turbo code suffers from high error floor due to its small Minimum Hamming Distance (MHD). Newly-proposed 3D-Turbo code can effectively increase the MHD and achieve a lower error floor by adding a rate-1 post encoder. In 3D-Turbo codes, part of the parity bits from the classical Turbo encoder are further encoded through the post encoder. In this paper, a novel Bit-Interleaved Coded Modulation (BICM) system is proposed by combining rotated mapping Quadrature Amplitude Modulation (QAM) and 3D-Turbo code to improve the Bit Error Rate (BER) performance of 3D-Turbo code over Raleigh fading channel. A key-bit protection scheme and a Two-Dimension (2D) iterative soft demodulating-decoding algorithm are developed for the proposed BICM system. Simulation results show that the proposed system can obtain about 0.8-1.0 dB gain at BER of 10^{-6}, compared with the existing BICM system with Gray mapping QAM.
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    Predicting the Probability of Spectrum Sensing with LMS Process in Heterogeneous LTE Networks
    (Společnost pro radioelektronické inženýrství, 2016-12) Hachemi, Mohammed Hicham; Feham, Mohammed; Adardour, Harroun Errachid
    Mobile communication systems present an actuality subject in academic and industrial research activities due to several phenomena such as interferences, multipath, fading, and shadowing. All this lead to a severe perturbation on handover mechanism which depends on specific reports, essentially, reference signal received power (RSRP) and signal-to-interference and noise ratio(SINR). In this paper, we design a new technique in handover domain; it consists of combining energy detection method used in cognitive radio with least mean square (LMS) process in order to prognosticate the handover impact in a realistic scenario of heterogeneous LTE network. More exactly, technique sense of the word "triggering" will be changed to a probability of detection Pd. The proposed algorithm cycle follows two main steps; Firstly, predict at what time the absence of spectrum (primary user) will occur, using a predicted sensing probability Pˆd (t+p) . Secondly, search others spectrums in this time by calculating Pd(t) for each sensed signal and hand-off secondary user in the best spectrum. The results achieved of the simulation are evaluating, it shows that the proposed method predict the original Pd correctly with minimal errors and select the best spectrum successfully.
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    VLSI Implementation of Fixed-Point Lattice Wave Digital Filters for Increased Sampling Rate
    (Společnost pro radioelektronické inženýrství, 2016-12) Agarwal, Meenakshi; Rawat, Tarun Kumar
    Low complexity and high speed are the key requirements of the digital filters. These filters can be realized using allpass filters. In this paper, design and minimum multiplier implementation of a fixed point lattice wave digital filter (WDF) based on three port parallel adaptor allpass structure is proposed. Here, the second-order allpass sections are implemented with three port parallel adaptor allpass structures. A design-level area optimization is done by converting constant multipliers into shifts and adds using canonical signed digit (CSD) techniques. The proposed implementation reduces the latency of the critical loop by reducing the number of components (adders and multipliers). Three design examples are included to analyze the effectiveness of the proposed approach. These are implemented in verilog HDL language and mapped to a standard cell library in a 0.18 μm CMOS process. The functionality of the implementations have been verified by applying number of different input vectors. Results and simulations demonstrate that the proposed design method leads to an efficient lattice WDF in terms of maximum sampling frequency. The cost to pay is small area overhead. The postlayout simulations have been done by HSPICE with CMOS transistors.
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    Performance of Diversity System Output Signal in Mobile Cellular System in the Presence of α-μ Short Term Fading and Gamma Long Term Fading
    (Společnost pro radioelektronické inženýrství, 2016-12) Krstic, Dragana; Jaksic, Branimir; Gligorijevic, Milan; Stefanovic, Dusan; Stefanovic, Mihajlo
    In this paper, wireless mobile communication system with macrodiversity reception is considered. Macrodiversity system is consisting of macrodiversity selection combining (SC) receiver and three microdiversity SC receivers. Propagation channel suffers α-μ short term fading and Gamma long term fading resulting in system performance degradation. Analytical closed form expression for average level crossing rate (LCR) of macrodiversity SC receiver output signal envelope is obtained. Mathematical results are analyzed, presenting the influence of long term fading parameters and short term fading parameters on average level crossing rate. Obtained results can be used in the process of simulation and design of real-world environments mobile cellular telecommunication systems.