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In this paper, a hybrid genetic algorithm (GA) is proposed for thinning a two-dimensional planar array by combining the conventional GA with moving least squares (MLS). This enhances the convergence rate and the global search performance. The MLS method is used to estimate local interpolation functions from non-uniform sample data (the population and the value of the objective function in the GA), and to find new and better populations from the interpolated functions. By incorporating these improved populations into the next generation, the MLS-GA achieves improved search performance of the global optimum and a faster convergence rate compared to conventional GA alone. Moreover, a nonlinear chirp function is used for an efficient thinning design. To verify the proposed MLS-GA, it is applied to a test function and the results are compared to that of the GA. The algorithm is then applied to thin an array with a rectangular grid and circular boundary. The design objectives are to minimize the peak side-lobe level and gain loss while satisfying a given thinning coefficient and to compare the results with the GA.

The accurate estimation of clutter covariance matrix (CCM) is essential in designing a radar detector/filter to suppress sea clutter. This estimation might not be easily accomplished because of the scarcity of valid training vectors adjacent to the range cell under test (CUT). We propose a new CCM estimation algorithm that is derived by modeling time-series clutter returns into a clutter Doppler spectrum in the frequency domain and exploiting mutual independence among spectral components. To justify its excellence over the conventional sample covariance matrix (SCM) algorithm, we design two filters—a maximum signal-to-interference-plus-noise ratio (SINR)-based filter and a whitening filter—that use the estimated CCMs and compare their performance in a numerically simulated sea clutter scenario. Comparisons are made by showing the eigenvector spectra of the estimated CCMs and the frequency responses and outputs of the filters. Moreover, SINRs at the target Doppler bin are examined and compared with a theoretical, analytically derived SINR.

This study presents a novel computationally efficient method for estimating the direction of departure (DOD) and direction of arrival (DOA) of targets and discriminates the DOA of jammer signals for a bistatic multiple-input, multiple-output (MIMO) radar system. Using properly designed projection filters, the proposed method replaces expensive exhaustive two-dimensional angle search with several one-dimensional angle search algorithms. The proposed method estimates DOD–DOA pairs of targets and discriminates jamming signals successfully regardless of the jamming signal strength. The performance of the proposed method is confirmed by simulation results.

A knowledge-aided space-time adaptive processing (STAP) is a quite useful technique to suppress non-stationary and heterogeneous clutter. It estimates a covariance matrix by combining a conventional covariance matrix based on secondary data with a synthesised one by prior information. A new combining method is presented, where weight vectors, rather than constant weights, are used to combine two covariance matrices. In this method, the weight vectors are derived in a way to maximise clutter-to-noise ratio of the combined covariance matrix. A numerical simulation is conducted for a bistatic radar scenario where clutter non-stationarity and heterogeneity can be assumed and the performance of the proposed method is demonstrated in terms of clutter suppression and target detection.

RFID based applications that combine radar techniques to obtain the location and the ID of a tag have widely been investigated. In this paper, we analyze a recently proposed RFID system that can extract the tag IDs and their velocities using signals transmitted from the tag attached moving objects and verify its performance. In the proposed system, a beacon transmits triggering signal at regular intervals into a monitoring area and the tag receiving the triggering signal backscatters the FMCW(frequency modulation continuous wave) signal modulated by the tag ID. The reader system demodulates this FMCW signal using predefined two reference signals to obtain not only the tag ID but its velocity. In this paper, we show that the proposed system works properly and analyze the degree of performance degradation in cases when the synchronization error between the transmitting signal and the reference signal occurs, and even when sampling rate is lowered for implementation purpose. Finally, the analytical results are verified by simulation.

In this paper we propose a waveform design algorithm that localizes the maximum output power in the target direction. We extend existing monostatic radar optimal waveform design schemes to bistatic multiple-input multiple-output (MIMO) radar systems. The algorithm simultaneously calculates the direction of departure (DoD) and the direction of arrival (DoA) using a two-dimensional multiple signal classification (MUSIC) method, and successfully localizes the maximum transmitted power to the target locations by exploiting the calculated DoD. The simulation results confirm the performance of the proposed algorithm.

In this paper, we apply the 2-D Matrix Pencil Method(MPM) to the estimation of the direction of arrival(DOA) of multiple signals of interest(SOIs) in bistatic MIMO radar. The 2-D MPM shows remarkable performance under a low SNR environment and low computational complexity to estimate the DOA of multiple SOIs. Also, it is possible to estimate the direction of departure(DOD) which is an angle from transmitter to target. To verify the proposed algorithm, we applied the proposed algorithm to a uniformly spaced linear array(ULA) and compared the RMSE(Root Mean Square Error) of DOA and DOD under the various SNR with those of the 2-D Capon algorithm.Key words: MIMO Radar, DOA/DOD, 2-D Matrix Pencil Method O0FP QRSMTPMU0FV6W %TPXYWZV [\]0F^_QRM2012`+abcUNNdU[0F- e)345fghij .k abcUNlmnopUM(Department of Electronic Convergence Engineering, Kwangwoon University) * qcUNrs_t pUu(Division of Computer and Communications Engineering, Korea University)**TPMU0FV(Agency for Defense Development)Manuscript received May 8, 2014 ; Revised May 30, 2014 ; Accepted June 2, 2014. (ID No. 20140508-043)Corresponding Author: Young-Seek Chung (e-mail: yschung@kw.ac.kr)

A monopulse based on maximum likelihood(ML) in jamming scenario can suppress jamming signal using an inverse matrix of a covariance matrix. In order to achieve adequate suppression of jamming signal, the sufficient number of snapshots is required. However, this is not possible in high PRF scenario, which hinders a real-time tracking. Moreover, even with the large number of snapshots, the estimation accuracy of the target direction is decreased in low JNR(Jammer to Noise Ratio) due to insufficient jammer suppression. In this paper, we propose a monopulse algorithm that doesn`t degrade performance significantly with a small number of snapshots and in low JNR. We show its derivation that exploits noise-jammer subspace of a covariance matrix, along with its performance through simulation.

A novel dual-band compact patch wireless fidelity (Wi-Fi) antenna using μ-negative (MNG) transmission lines (TLs) for the smart helmet is presented. In the smart helmet scenario, rescue agent is able to communicate with the other rescue agents, control centre, and drones via the helmet by Wi-Fi dual bands. For the smart helmet communication, the antenna, which consists of two MNG-TL loops located on the outside and inside, is devised. The dual-band corresponds to the zeroth-order resonance (ZOR) and second-positive-order resonance (SPOR) of the outer MNG-TL. The ZOR frequency of the outer MNG-TL is near the Wi-Fi 2.4 GHz band, and the SPOR frequency of the outer MNG-TL, excited by the coupling between the inner and outer MNG-TL loops, is the Wi-Fi 5 GHz band. The prototype of the proposed antenna has been fabricated and measured. The bandwidth of the antenna includes Wi-Fi 2.4 and 5 GHz bands with high radiation efficiencies of >49% and a compact size of 27.6 mm × 27.6 mm × 1.27 mm (1/4.5 λ × 1/4.5 λ × 1/98.4 λ at the lowest operating frequency).

To successfully accomplish a bit synchronization, a synchronizer should exploit a preamble pattern. A MFM (modified frequency modulation) flag is uses as a preamble in a PJM (phase jitter modulation) mode RFID standard. In the recent work, a synchronizer for a PJM mode tag was proposed, which is composed of several correlators. In this paper, we present a new bit synchronizer in which a coarse synchronization is done as in the previous work while a fine synchronization is performed via exploiting a violation bit included in the MFM flag. We show that the proposed synchronizer can significantly reduce the overall hardware complexity at the expense of slight burden to a demodulator structure. Through simulation, we also show that its performance is comparable to that of the previous system despite its hardware simplicity.

In order to execute coherent Doppler processing in a high range-rate scenario, whether it is for detection, estimation or imaging, range walk embedded in target return should be compensated first. In case of a bistatic radar geometry where a transmitter, a receiver and a target can be all moving, the extent of range walk depends on their relative positions and velocities. This paper presents a coherent Doppler processing algorithm to achieve target detection and Doppler frequency estimation of a target under a bistatic radar geometry. This algorithm is based on the assumption that a target has constant Doppler frequency during a coherent processing interval (CPI). Thus, we first show under what condition the assumption could be valid. We next develop an algorithm, along with its implementation procedures where the region of range walk, called a window, is manipulated. Finally, the performance of a proposed algorithm is examined through simulations.

In this paper, we propose the algorithm which considers applying recently proposed clock synchronization techniques with quite high accuracy in a few wireless sensor networks researches to time synchronization algorithm for multi-static radar system and especially overcomes the limitation of previous theory, cannot be applied between nodes in non-line of sight (NLOS). Proposed scheme estimates clock skew and clock offset using recursive robust least M-estimator with information of time stamp observations. And we improve the performance of algorithm by tracking and suppressing the time delays difference caused by NLOS system. Futhermore, this paper derive the mean square error (MSE) to present the performance of the proposed estimator and comparative analysis with previous methods.

The performance of a monopulse estimator is depend on its monopulse ratio(MR) curve. To improve its performance, a mathematical expression of the MR curve that is associated with an array the parameters is needed. In this paper, we present a novel monopulse estimator that uses the inverse function of a MR curve for the Maximum Likelihood (ML)-based monopulse estimator. It is shown that the proposed method can extend the linear region of the MR curve, which in turn improve the estimation accuracy. Moreover, it`s performance is compared with the ML-based method through simulation.

In this paper, we propose the optimization of subarray configurations for linear array to minimize the side lobe level (SLL) in sum beam pattern based on the genetic algorithm. The operations of genetic algorithm are modified to be applied to subarray configurations. Using the proposed method, we construct subarray structure with 16 irregular subarray elements from 40 linear array elements to minimize the SLL in sum beam pattern in case of applying the adaptive beamforming(ABF) to suppress the jamming power, whose the SLL is 10 dB lower than that of regular subarray configuration.

Range walk has been a major problem in achieving correct Doppler processing. This frequently occurs when range variation is severe just like in a bistatic radar or in high speed target scenario. This paper presents a range walk compensated range-Doppler processing algorithm applicable to the bistatic radar. In order for the compensation, a range-domain interpolation is applied for range compressed signal so that Doppler processing is performed along the evenly time-spaced range bins that contain target returns. Under a bistatic radar scenario, the proposed algorithm including a range domain pulse compression is mathematically described. Finally, the validity of the algorithm is demonstrated by simulation results showing the superiority of a SCDP(Squint Cross-range Doppler Processing) over an uncompensated Doppler processing.

In this paper, we propose a coordinator-based reader protocol that can avoid reader collisions in a passive RFID system. In a proposed protocol, unlike conventional protocols that a reader itself selects its own slot randomly to communicate with tags such as DCS, Colorwave, a coordinator reader allocates an unused slot to a reader to participate in the network and sends a current slot number. A reader allocated a slot can communicate with tags. The proposed protocol can adaptively modified to apply for multiple coordinator readers environment in a wide area. This causes reader collision problem, but can be alleviated partly by applying the frequency planning. In this way, we verifies that a RFID system using the proposed protocol is three to five times better than existing systems through the simulation.

This paper presents the mathematical derivation of a maximum likelihood(ML)-based monopulse ratio(MR) curve. The derived form is, with the linear array assumed, shown to be the function of the number of array elements and the elements` spacing. Through some simulations, the acquired form is equivalent to the expected MR curve. Furthermore, we show the form, which consists of several terms, can be simplified by one tangent function.

In this paper, we have proposed a M&S tool for analyzing detection coverage and target localization in bistatic radar system. The detection coverage determined by radar parameters is meaningful when it satisfies the clear line-of-sight condition. We improved the method to find the minimum altitudes of transmitter and receiver for meeting the condition by considering three-dimensional coverage. Its computational burden is not problematic because the calculation is for maximizing the performance of the radar and does not demand a real-time operation. In addition, target localization on three-dimensional earth model based on the information of the height, longitude, and latitude is proposed instead of the previous unpractical calculation on two-dimensional bistatic plane. Its precalculated result can reduce its computation burden and it is suitable for real-time estimation of target location.

In this paper, we propose the design procedure of a digital IF system for the OFDM based WLAN system and examine its performances. Along with the decision procedure of ADC sample rate, NCO frequency and the required decimation ratio, we show the decimation ratio is accomplished through the use of a CIC filter and a MHBF. We also show that the amplitude distortion occurred in the decimation filters can effectively be compensated by a ISOP filter and an additional FIR filter, which leads to the reduction of the overall hardware complexity. Finally, we examine the BER performance of the proposed system and compare it with a theoretical one that excludes filter non-linearities.

This paper proposes a M & S Tool for simulating the detection performance in the bistatic radar system. After examing the interrelationship among the bistatic radar parameters, (probability of detection), (probability of false alarm) and ��SNR of the received signal, we analyze the range of the bistatic radar range product and range sum. We derive the number of integration of the received pulses that satisfies the required detection performance of the bistatic radar system, along with the analysis of the performance degradation in the jammer scenario. Finally, the analyzed results are implemented in the M & S Tool which consists of 4 modules.

This paper presents a time-domain based asynchronous IR-UWB ranging system. This system accomplishes the ranging by detecting peaks from the outputs of a correlator implemented by a FIR filter. To discriminate the peaks due to a signal component, we use windowing for the correlated data within which the data are sorted in amplitude-ascending order and the noise level is calculated. Comparing with the recently presented frequency-domain based ranging system, we show the system structure and explain how it operates for ranging. Moreover, through the simulations, the proposed system is compared with the frequency-domain based system in terms of performance.

In this paper, we propose an asynchronous IR-UWB ranging system based on the two-way ranging protocol. The periodic pulse sequence is used to measure a distance between two devices. At the receiver, a received signal is first transformed into a frequency-domain signal using an analog correlator bank and digital signal processing is followed in the frequency-domain. This make it possible for the system to use an ADC with a conversion speed of pulse rate. The proposed algorithm at the receiver side includes a peak detection procedure using mutipath channel compensation and matched filtering, and retransmits a pulse sequence synchronized with the detected peak. The validity of the proposed algorithm is verified from simulation results where the CM1 channel is assumed.

In this paper, we propose the simplified and improved system of One Color Detector to protect color distortion of simple color images in the processed of Auto White Balance (AWB). The proposed One Color Detector is based on Grayworld algorithm which controls color compensation except one color in simple image and widely applies for mobile phone camera because of high efficiency. This system can be suitable for diverse image size, and let user control the threshold in diverse size and environments compared with conventional system. Also the hardware size of the proposed system is reduced by 80% over that of the conventional one.

This paper presents a coordinator-based TDMA reader protocol that can avoid the reader collision in a passive RFID system. In the proposed protocol, the coordinator can not only minimize the number of empty slots by efficiently allocating slots to readers incoming in Poisson distribution, but reduce latency time through the limited frame size. The proposed protocol can be implemented in either mobile or fixed mode through the slot structure to be described in the context. The simulation results show it works as suggested and the frame size limitation as well as the statistical distribution of incoming readers has a great impact on the overall slots and the average latency time.

본 논문은 얼굴을 관심 영역(ROI)으로 사용하는 자동 초점(AP, Auto Focusing) 시스템을 위한 얼굴 검출 기능(Face Detection)의 얼굴 추적 향상방법에 관한 것이다. 피부색을 바탕으로 얼굴을 검출하는 기존의 얼굴 검출 기능에서는 얼굴을 추적하기 위하여 이전 프레임에 검출된 얼굴 영역에 대하여 현재 프레임의 스킨 픽셀 비율을 사용한다. 이 방법은 동영상에서 얼굴영역의 안정성은 뛰어나지만, 얼굴추적 성능은 다소 떨어진다. 따라서 얼굴추적 성능을 향상시키기 위하여, 이전프레임에 검출된 얼굴영역과 현재 프레임에 검출된 얼굴영역의 겹침을 조사하여 겹치는 영역의 면적을 이용하여 얼굴을 추적 하는 방법을 제안하였다. 검증을 위하여 FPGA 보드와 모바일 폰 카메라용 CIS를 이용하여 실시간으로 열굴 검출을 촬영하였고, 검출된 얼굴의 이동 궤적을 이용하여 성능을 검증하였다.

This letter presents a new TR-UWB receiver exploiting frequency components of UWB pulses. This is accomplished by separating frequency-components of UWB pulses into real and imaginary parts, independently correlating and effectively combining them. We analytically show this scheme improves the output SNR compared with a conventional one using complex correlation. This will also be justified by simulation results.

This paper presents a simulation based method to predict the amount of frequency interference in a passive type RFID system. To judge occurrence of frequency interference, we use a parameter POI (probability of interference) that depends on several factors such as multiple access method, emission mask, the number of channel, etc. Due to its dependence on several factors, a Monte-carlo based simulation is suitably used. Through the simulation, we draw minimum separation distance between two readers and examine performance degradation due to aggregate interfering readers. Moreover, we present a reader deployment strategy based on the average POI of active readers operating in some area.

The methods of bandwidth measurement in the field environments are notified in ITU-R spectrum monitoring(SM) documents. But, these methods for terrestrial DTV and T-DMB are not informed yet. The x-dB bandwidth is the most suitable method fer the bandwidth measurement of terrestrial digital broadcasting signals. So, we proposed the suitable x-dB value for x-dB bandwidth measurement of the digital broadcasting signal that is not notified in ITU-R SM documents. As a result, we derived the x dB value of -12 dB and -8 dB that can be used fer estimation of occupied bandwidth of DTV and T-DMB signals respectively by x dB bandwidth measurement in field environments.

This paper presents a compact antenna geometry to realize an radio frequency (RF) system in package (SIP) and discusses an antenna-integrated package for an IEEE 802.11a application. The proposed compact antenna is similar to a modified U-shaped slot antenna; however, its electrical properties are quite different. A fabricated antenna demonstrates bandwidth of 180 MHz at a center frequency of 5.8 GHz, and it may be used to implement antenna-integrated packages. An antenna-integrated package is proposed consisting of the antenna placed on the top surface, internal space for integration of other IC components, a conducting layer placed between the antenna and the internal space, and finally a bottom layer. In addition, from the parametric studies it is found that the size of the package, dielectric thickness of the antenna, package height, and the number as well as the position of via holes, are critical factors of antenna characteristics