2017/3

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FPGA-based Low Latency Inverse QRD Architecture for Adaptive Beamforming in Phased Array Radars
(Společnost pro radioelektronické inženýrství, 2017-09) Irfan, Raafia; Rasheed, Haroon Ur; Toor, Waqas Ahmed
The main objective of this paper is to facilitate the adaptive beamforming which is one of the most challenging task in phased array radars receivers. Recursive least square (RLS) is considered as the most well suited adaptive algorithm for the applications where beamforming is mandatory, because of its good numerical properties and convergence rate. In this paper, some RLS variants are discussed and the most numerically suitable algorithm Inverse QRD is selected for efficient adaptive beamforming. A novel architecture for IQRD RLS is also presented, which offers low latency and low area occupation for Field Programmable Gate Array (FPGA) implementation. This approach reduces the computations by utilizing the standard pipelining methodology. Hence, efficient adder and multipliers and LUT based solution for square root and division, has highly enhanced the performance of the algorithm. The proposed IQRD RLS architecture has been coded in Verilog and analyze its performance in terms of throughput, hardware resources and efficiency.
Wireless Powered Relaying Networks Under Imperfect Channel State Information: System Performance and Optimal Policy for Instantaneous Rate
(Společnost pro radioelektronické inženýrství, 2017-09) Dinh-Thuan Do; Hoang-Sy Nguyen; Voznak, Miroslav; Thanh-Sang Nguyen
In this investigation, we consider wireless powered relaying systems, where energy is scavenged by a relay via radio frequency (RF) signals. We explore hybrid time switching-based and power splitting-based relaying protocol (HTPSR) and compare performance of Amplify-and-Forward (AF) with Decode-and-Forward (DF) scheme under imperfect channel state information (CSI). Most importantly, the instantaneous rate, achievable bit error rate (BER) are determined in the closed-form expressions under the impact of imperfect CSI. Through numerical analysis, we evaluate system insights via different parameters such as power splitting (PS) and time switching (TS) ratio of the considered HTPSR which affect outage performance and BER. It is noted that DF relaying networks outperform AF relaying networks. Besides that, the numerical results are given to prove the optimization problems of PS and TS ratio to obtain optimal instantaneous rate.
A Blind Adaptive Color Image Watermarking Scheme Based on Principal Component Analysis, Singular Value Decomposition and Human Visual System
(Společnost pro radioelektronické inženýrství, 2017-09) Imran, Muhammad; Harvey, Bruce A.
A blind adaptive color image watermarking scheme based on principal component analysis, singular value decomposition, and human visual system is proposed. The use of principal component analysis to decorrelate the three color channels of host image, improves the perceptual quality of watermarked image. Whereas, human visual system and fuzzy inference system helped to improve both imperceptibility and robustness by selecting adaptive scaling factor, so that, areas more prone to noise can be added with more information as compared to less prone areas. To achieve security, location of watermark embedding is kept secret and used as key at the time of watermark extraction, whereas, for capacity both singular values and vectors are involved in watermark embedding process. As a result, four contradictory requirements; imperceptibility, robustness, security and capacity are achieved as suggested by results. Both subjective and objective methods are acquired to examine the performance of proposed schemes. For subjective analysis the watermarked images and watermarks extracted from attacked watermarked images are shown. For objective analysis of proposed scheme in terms of imperceptibility, peak signal to noise ratio, structural similarity index, visual information fidelity and normalized color difference are used. Whereas, for objective analysis in terms of robustness, normalized correlation, bit error rate, normalized hamming distance and global authentication rate are used. Security is checked by using different keys to extract the watermark. The proposed schemes are compared with state-of-the-art watermarking techniques and found better performance as suggested by results.
Discrete Frequency and Phase Coding Waveform for MIMO Radar
(Společnost pro radioelektronické inženýrství, 2017-09) Chang, Guanghong; Yu, Xiaoxi; Yu, Changjun
In multi-input multi-output (MIMO) radar system, good orthogonality between transmitting waveforms will fairly simplify the signal processing, along with improve the targets detection as well as the parameters estimation performance of the system. In this paper, a discrete frequency and phase coding waveform (DFPCW), which attains good orthogonality by varying the carrier frequency and initial phase of each pulse in the pulse train, is designed. The theoretical derivations of ambiguity function (AF) and cross ambiguity function (CAF) of the DFPCW are also given. After then, a generic algorithm (GA) is applied by optimizing the carrier frequency code sequence and initial phase code sequence to minimize both the auto-correlation sidelobe peaks (ASP) and cross-correlation peaks (CP) of the waveforms. The simulation results demonstrate that DFPCW has better orthogonality and sidelobe property compared with the traditional discrete frequency coding waveform and widely employed frequency modulated continuous wave (FMCW), henceforth this new waveform may become to an alternative option for MIMO radar.
Promotion of GM-PHD Filtering Approach for Single-Target Tracking in Raw Data of Synthetic Aperture Radar in Spotlight Imaging Mode
(Společnost pro radioelektronické inženýrství, 2017-09) Daryasafar, Navid; Sadeghzadeh, Ramazanali; Naser-Moghadasi, Mohammad
So far multi-antenna techniques have been used in Synthetic Aperture Radar (SAR) to track moving targets. These techniques carry out the tracking of moving targets in an imaging area, using a combination of the data received by two or several antennas. The aim of this paper is single-target tracking in SAR Spotlight imaging mode based on the promoted PHD filter. In most applications, target tracking in densely cluttered environment using radar system demands robust filtering so as to increase the tracking efficiency. Therefore, tracking of moving targets in the presence of high density clutters in environment, as the particular capability of the PHD filter, has turned it into a robust approach in SAR to track moving targets. Also as the simulation results show, using Range Cell Migration Compensation (RCMC) on SAR raw data before tracking, makes it possible to track a moving target with high quality.

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