52 research outputs found
Joint Smoothed l0-Norm DOA Estimation Algorithm for Multiple Measurement Vectors in MIMO Radar
No full textDirection-of-arrival (DOA) estimation is usually confronted with a multiple measurement vector (MMV) case. In this paper, a novel fast sparse DOA estimation algorithm, named the joint smoothed l 0 -norm algorithm, is proposed for multiple measurement vectors in multiple-input multiple-output (MIMO) radar. To eliminate the white or colored Gaussian noises, the new method first obtains a low-complexity high-order cumulants based data matrix. Then, the proposed algorithm designs a joint smoothed function tailored for the MMV case, based on which joint smoothed l 0 -norm sparse representation framework is constructed. Finally, for the MMV-based joint smoothed function, the corresponding gradient-based sparse signal reconstruction is designed, thus the DOA estimation can be achieved. The proposed method is a fast sparse representation algorithm, which can solve the MMV problem and perform well for both white and colored Gaussian noises. The proposed joint algorithm is about two orders of magnitude faster than the l 1 -norm minimization based methods, such as l 1 -SVD (singular value decomposition), RV (real-valued) l 1 -SVD and RV l 1 -SRACV (sparse representation array covariance vectors), and achieves better DOA estimation performance
PAPR reduction using Huffman coding combined with clipping and filtering for OFDM transmitter
No full textExploiting LDPC Codes For Improving The Performance of Clipped-OFDM System
No full textOrthogonal Frequency Division Multiplexing (OFDM) is a multicarrier
transmission technique that becomes the best choice in wireless
high-data-rate transmission. The drawbacks of OFDM are high
Peak-to-Average Power Ratio (PAPR) and sensitivity to frequency offset.
High PAPR decreases the amplifier’s efficiency. The simplest PAPR
reduction method is clipping, but it gives in-band and out-of-band
distortion that degrades the performance of the system. There are
various types of clipping, such as classical clipping, deep clipping,
and smooth clipping. This paper analyses the use of low-density
parity-check (LDPC) codes as an error correction coding (ECC) for those
various types of clipping. The simulation results show that classical
clipping gives the best performance in PAPR reduction and error
probability
Portable Micro-Doppler Radar with Quadrature Radar Architecture for Non-Contact Human Breath Detection
No full textRecently, rapid advances in radio detection and ranging (radar) technology applications have been implemented in various fields. In particular, micro-Doppler radar has been widely developed to perform certain tasks, such as detection of buried victims in natural disaster, drone system detection, and classification of humans and animals. Further, micro-Doppler radar can also be implemented in medical applications for remote monitoring and examination. This paper proposes a human respiration rate detection system using micro-Doppler radar with quadrature architecture in the industrial, scientific, and medical (ISM) frequency of 5.8 GHz. We use a mathematical model of human breathing to further explore any insights into signal processes in the radar. The experimental system is designed using the USRP B200 mini-module as the main component of the radar and the Vivaldi antennas working at 5.8 GHz. The radar system is integrated directly with the GNU Radio Companion software as the processing part. Using a frequency of 5.8 GHz and USRP output power of 0.33 mW, our proposed method was able to detect the respiration rate at a distance of 2 m or less with acceptable error. In addition, the radar system could differentiate different frequency rates for different targets, demonstrating that it is highly sensitive. We also emphasize that the designed radar system can be used as a portable device which offers flexibility to be used anytime and anywhere
Rectangular Microstrip Array Feed Antenna for C-Band Satellite Communications: Preliminary Results
No full textThis paper proposes a rectangular array configuration of microstrip antennas combined with a parabolic reflector for C-band satellite communications. The antenna operates in the frequency range of 3.8–4.2 GHz. In particular, the proposed antenna is a 2 × 2 feed antenna on a parabolic system. It uses a multilayer microstrip array antenna with proximity coupling and coaxial probe techniques as a feeding technique. The fabricated antenna operates at 3.8–4.4 GHz and 12.1 dBi gain at frequency 4.148 GHz. Through simulation, combining the antenna with a 2.4 m parabolic reflector results in a gain of 33.1 dBi. In conclusion, the proposed antenna configuration achieves the expected high gain and narrow beamwidth for the E plane and the H plane
Differentially fed compact dual-band implantable antenna for biotelemetry
No full text© 2016 IEEE. A novel differentially fed dual-band planar antenna operating at the medical implant communication service (MICS) band (402-405 MHz) and the industrial, scientific and medical (ISM) bands (2400-2480 MHz) is presented. The measured 10-dB differential reflection coefficient bandwidth is 389-419 MHz (7.4%) at the lower band and 2395-2563 MHz (6.6%) at the upper band, respectively. The volume of the implantable antenna is only 642.62 mm3 (22mm×23mm×1.27mm)
Analyzing factors influencing global precious metal markets: A feature selection study
No full textPrecious metals are valuable commodities providing superior protection against risky financial exposure. Identifying factors influencing the market is crucial for anticipating changes. Forecast applications utilize stochastic models capable of learning from historical data to project future values. The dataset is a vital component for prediction tools since all estimations begin with constructing the appropriate information. Detecting the association between input and output is essential to filter data, as including unrelated variables could destabilize the response. Feature selection considers removing uncorrelated attributes before incorporating them as inputs to the predictor. This study employs three regression-based algorithms to examine 58 precious assets from gold, silver, platinum, and palladium markets against several variables cited in the literature. Relationships were detected using regressive feature selection methods, known as least absolute shrinkage and selection operator (LASSO), ridge, and elastic net (EN). Results demonstrate that the proposed algorithms achieved satisfactory performance on 42 assets, justified through a reliable fit and acceptable error. The remaining 16 assets exhibited large deviations with considerably poor regression quality, indicating considerable nonlinearity. Attributes were selected with a detailed emphasis on those exerting the most substantial impact on a particular metal. Based on computational analysis, most investments are susceptible to macroeconomic factors. Some assets may present hedging capabilities towards key features, including stock index, exchange rates, and bond yield. An assessment of common variables among each metal revealed that real GDP growth and interest rates are vital indicators for the precious metal market. Overall, the simulation outcomes show no consistent commonalities amongst attributes within the same asset class in a country. Feature selection from this research offers necessary information regarding time-series dynamics, serving as a basis to project trends. The filtered dataset is expected to enhance the reliability of nonlinear predictive algorithms by removing inaccurate correlations to lower computational load. Furthermore, the outcome provides information regarding correlations affecting global precious metal investments over five-year period. These discussions are necessary for investors considering such commodities as potential portfolio diversifiers
Cyclic shift resolution effects on OFDM system employing cyclic-SLM with delayed correlation and matched filter
No full text© 2017 IEEE. Large peak-to-average power ratio (PAPR) is the major issue in orthogonal frequency-division multiplexing (OFDM) systems. Selective mapping (SLM) has been commonly employed to reduce the PAPR. However, SLM requires side information (SI) which reduce the bandwidth efficiency. A low-complexity cyclic SLM (C-SLM) scheme without SI which uses delay correlation and matched filter, called C-SLM-DC-MF, has been proposed in the literature. This paper examines the effects of cyclic shift resolution of the OFDM system with C-SLM-DC-MF scheme on the system performance, in terms of PAPR reduction, accuracy, and bit error rate (BER). Simulation results show that higher resolution leads to lower PAPR reduction but better accuracy and BER performance
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