Cancellation Method Research Articles

Real-Time Ventricular Cancellation in Unipolar Atrial Fibrillation Electrograms.

Unipolar atrial fibrillation (AF) electrograms (EGMs) require far-field ventricle cancellation to recover hidden atrial activations. Current methods cannot achieve real-time cancellation because of the temporal delay they introduce. We propose a new real-time ventricular cancellation (RVC) method based on causal implementation optimized for real-time functioning. The method is similar to the classical average beat subtraction (ABS) method but it computes the ventricular contribution before the ventricular activation finishes. We compare the proposed method to the ABS on synthetic and real EGM databases for the time and frequency domains. All parameters and their optimal values are analyzed and validated. The RVC method provides a good reconstruction of the unipolar EGMs and a better local activation time detection than the classical approach with average F1scores 0.7307 and 0.7125, respectively. The spectral analysis shows that the average power after ventricular cancellation is reduced for frequency bands between 3 and 5.5 Hz, demonstrating that the proposed method removes the ventricular component present in the unipolar EGM signals compared to the ABS method. The phase mapping analysis on the RVC method presented lower error when comparing the annotated EGM cycles with the phase inversion intervals. In terms of performance ABS and RVC behave similarly, but the real-time capability of the latter justifies its preference over the offline implementations. In the clinical environment other online investigations, e.g., rotational activity assessment, dominant frequency or local activation time mapping, might benefit from the real-time potential of the proposed cancellation method.

Mainlobe jamming suppression with polarimetric multi-channel radar via independent component analysis

Mainlobe jamming will reduce the capabilities of modern radar significantly. Conventional independent component analysis (ICA)-based methods will suffer from the ineffectiveness when the angle of the target is same as that of the jammer. In this paper, exploring polarization characteristics, we propose an approach based on ICA for polarimetric multi-channel radar to suppress mainlobe interference. Specifically, the signal model of polarimetric multi-channel radar accounting for the target and jamming signals is derived. Then, the approach based on ICA is utilized to separate the target component and jamming component while achieving the mainlobe jamming suppression. Finally, the effectiveness and capacities of proposed method are demonstrated by simulations, and the results indicate that different kinds of mainlobe jammings can be effectively suppressed and the proposed method outperforms conventional jamming cancellation methods.

Illusion thermotics with topology optimization

Illusion thermotics, which aims at creating temperature fields to mislead a thermal detector, encompasses many thermal functionalities. It has attracted significant attention due to the increasing number of promising applications. Transformation thermotics and scattering cancellation methods are frequently adopted for illusion devices, though they have inherent defects such as anisotropic thermal properties and complicated fabrication methods. Here, we present a general framework for topology optimization, which can be used to design the structure of an illusion device automatically. The optimized configuration can camouflage the thermal exterior of an illusion device so that it is identical to a reference. The original heat source can drive the virtual heat source despite the structure being simply composed of natural materials. To establish an effective topology optimization model, a volume constraint was imposed on the total volume of iron and a prescribed objective function was used to evaluate the difference between the reference temperature and the temperature field during the topology optimization. The flexibility of the method presented was successfully validated by changing the total volume of iron, the number and locations of the thermal illusions, the types of composite materials, and the original heat sources. Topology optimization is a new and flexible approach for designing thermal metamaterials and metadevices for diverse thermal functionalities and beyond.

Optimal Antenna Arrangement for Self-Interference Cancellation in Short-Range Full-Duplex MIMO

A self-interference cancellation (SIC) method is presented for short-range full-duplex multiple-input-multiple-output (MIMO) communication. The proposed SIC consists of the following steps. First, each peer has multiple transmitting (Tx) and receiving (Rx) antennas optimally arranged to form a one-rank self-interference (SI) matrix between Tx and Rx. The optimal antenna arrangement is derived using a geometric model. Second, null steering is performed by eigenmode beamforming excluding the primary eigenmode of the SI matrix. This realizes powerful SIC at the cost of processing just a single degree of freedom. The effectiveness of the proposed SIC is evaluated by electromagnetic simulations. The results confirm that it reduces the SI level by 22.76 dB. In addition, it is shown the proposal offers achievable rates 1.50 times those of the half-duplex scheme in line-of-sight (LOS).

Artificial neural networks applied to the measurement of lateral wheel-rail contact force: A comparison with a harmonic cancellation method

This paper presents a method for the experimental measurement of the lateral wheel-rail contact force based on Artificial Neural Networks (ANN). It is intended to demonstrate how an Artificial Intelligence (AI) method proves to be a valid alternative to other approaches based on sophisticated mathematical models when it is applied to the wheel-rail contact force measurement problem. This manuscript addresses the problem from a computational and experimental approach. The artificial intelligence algorithm has been experimentally tested in a real scenario using a 1:10 instrumented scaled railway vehicle equipped with a dynamometric wheelset running on a 5-inch-wide track. The obtained results show that the ANN approach is an easy and computationally efficient method to measure the applied lateral force on the instrumented wheel that requires the use of fewer sensors.

Hybrid Passive Cancelation Method for Reducing Common-Mode Noise in Isolated Power Converters

The shielding technique is an effective method for reducing the common-mode (CM) electromagnetic interference in an isolated power converter. However, the interwinding capacitance between the shielding layer and its adjacent winding provides the path for CM noise current. This CM noise current can be suppressed by making the averaged electric potential (AEP) of the shielding layer and its adjacent winding be equal. In this article, a balancing winding is introduced to be connected with the shielding layer for adjusting the AEP of the shielding layer to be equal to that of its adjacent winding and, thus, canceling the CM noise current. Furthermore, the hybrid passive cancelation (HPC) method is proposed in which the balancing winding is reused as the compensation winding to generate the compensation voltage for canceling the noise current flowing through the parasitic capacitance between the high dv / dt node in the primary circuit and protective earth. The proposed shielding technique with balancing winding and the HPC method are verified by the experimental results.

Adaptive Self-Interference Suppression for Full Duplex Filter-and-Forward Relaying

This letter proposes a self-interference (SI) suppression method for in-band full duplex relaying. SI is suppressed by using a feedforward linear FIR filter which is adaptively adjusted in a blind manner. Simulation results show that the proposed method can suppress SI successfully and is less sensitive to transceiver hardware imperfections than the conventional SI cancellation methods using feedback filters.

An Enhanced Second Carrier Harmonic Cancellation Technique for Dual-Channel Enhanced Power Generation Centre Applications in More-Electric Aircraft

The more-electric aircraft concept has made the extraction of electrical power from both high-pressure shaft and low-pressure shaft of the aircraft engine essential for future aircraft. With each shaft driving one electrical generation channel, an advanced dual-channel enhanced power generation system can be formed. This article aims to address the power quality issues of this dual-channel power generation system, specifically focusing on the reduction of harmonics on a common dc bus. A simplified model to estimate second carrier harmonic of dc current in two-level converters is developed and reveals the fact that while this second carrier harmonic component magnitude can be determined by modulation index and dc-link current, its phase angle is solely dependent on the angle of carrier signals. Based on the developed model and these key findings, a new harmonic cancellation method is proposed through active power sharing and phase angle shifting of the carrier signals within different power sources. The method has demonstrated high robustness and is effective under different fundamental frequencies and power sharing ratio. Both simulation and experimental results are presented in this article to validate the proposed harmonic model and the enhanced cancellation method.

Performance Analysis of OFDM With Peak Cancellation Under EVM and ACLR Restrictions

This paper presents performance analysis of an adaptive peak cancellation method to reduce the high peak-toaverage power ratio (PAPR) for OFDM systems, while keeping the out-of-band (OoB) power leakage as well as an in-band distortion power below the pre-determined level. In this work, the increase of adjacent leakage power ratio (ACLR) and error vector magnitude (EVM) are estimated recursively using the detected peak amplitude. We present analytical framework for OFDM-based systems with theoretical bit error rate (BER) representations and detection of optimum peak threshold based on predefined EVM and ACLR requirements. Moreover, the optimum peak detection threshold is selected based on the oretical design to maintain the predefined distortion level. Thus, their degradations are automatically restricted below the pre-defined levels which correspond to target OoB radiation. We also discuss the practical design of peak-cancellation (PC) signal with target OoB radiation and in-band distortion through optimizing the windowing size of the PC signal. Numerical results show the improvements with respect to both achievable bit error rate (BER) and PAPR with the PC method in eigen-beam space division multiplexing (E-SDM) systems under restriction of OoB power radiation. It can also be seen that the theoretical BER shows good agreements with simulation results.

Development of an inductive noise cancellation method for quench detection of the KSTAR CS coils by introducing improved plasma modeling

An inductive noise cancellation method, CDA+MIK, has been developed for better performance of KSTAR (Korea Superconducting Tokamak Advanced Research) CS (Central Solenoid) coils’ quench detection. The CDA+MIK method was evaluated in real operations of the KSTAR superconducting coils. An analysis of this evaluation considering mutual inductances only among CS and PF (Poloidal Filed) coils showed insufficient reduction of the inductive noise in the quench detection signal. On the other hand a supplementary analysis taking into account of eddy currents induced on conductive structures and dynamic plasma evolutions capable to induce voltages showed better reduction even though the inductive noise was under-estimated. This paper describes an improved plasma modelling by considering plasma’s volume and shape, and also application of the model to the experimental results

Adjacent Channel Interference Cancellation in FDM Transmissions

Interference between users in adjacent channels negatively affects throughput of mobile networks. In this paper we aim at cancellation of interference caused by a nonlinear power amplifier in a generalized orthogonal frequency division system. We propose an interference cancellation method to subtract these out-of-band emissions from the received signal. In contrast to state-of-the-art methods, our proposed method employs over-the-air estimation of power amplifier model parameters together with a particular frequency domain filtering method that allows to generate the required training data. The proposed interference cancellation method is also verified by an experiment on a software defined radio test bench.

Iterative Interference Cancellation for Non‐orthogonal Multiple Access System

Non-orthogonal multiple access (NOMA) makes multiple users to overload the same wireless resources by utilizing the superposition coding principle, so that it can improve the system capacity and spectral efficiency. Various NOMA schemes are proposed, including the Power-domain NOMA (PD-NOMA). Most of them are using Successive interference cancellation (SIC) for detection, which limits the promised performance gain brought by NOMA due to the error propagation. An Iterative SIC and parallel interference cancellation (ISP) method is proposed for the PD-NOMA system. The MaxLog-MAP (MLM) algorithm (MAP is short for Maximum a posteriori) and SIC are used for performance comparison. Simulation results show that the Bit error rate (BER) performance of ISP is much better than that of SIC, and is close to that of MLM. It can perform even better than MLM at low signal to noise ratio for the user with lower power allocation. The ISP can obtain the promised performance gain brought by NOMA.

LPI performance optimisation strategy for a JRCS

In this study, the problem of the low probability of intercept (LPI) performance optimisation for a joint radar-communications system (JRCS) is investigated, which can simultaneously estimate surveillance channel parameters from the target returns and decode the received communications signals. The primary purpose of the proposed LPI performance optimisation strategy is to improve the LPI performance of a JRCS by optimising the energy spectral density of radar waveform design and the communications power allocation while maintaining a predetermined mutual information threshold for parameter estimation and a certain communications data rate for information delivery. The traditional isolated sub-band (TISB) situation, radar isolated sub-band (RISB) situation, and communications isolated sub-band (CISB) situation are analysed. Subsequently, the technique of Lagrange multipliers and the Karush-Kuhn-Tuckers optimality conditions are employed to solve the resulting optimisation problems. Moreover, the successive interference cancellation method is adopted to process the received radar-communications compound signal. Finally, several numerical simulations are conducted to demonstrate the theoretical calculations and to validate the effectiveness of the proposed LPI performance optimisation strategy. It is also shown that the achievable LPI performance in RISB and CISB situations is much better than that in TISB situation.

A Novel Primary-Side Regulation Control Scheme for CCM and DCM LLC LED Driver Based on “Magnetizing Current Cancellation Method”

In this article, the primary-side regulation (PSR) technique to achieve accurate output current in an LLC resonant converter has been studied. A novel PSR control scheme for an LLC light-emitting diode (LED) driver based on the “magnetizing current cancellation method” is proposed. The proposed “magnetizing current cancellation method” can effectively eliminate the effect of magnetizing current in the sampled primary resonant current under both the continuous conduction mode and the discontinuous conduction mode. Thus, the accurate output current can be estimated on the primary side of the LLC resonant converter. The magnetizing current cancellation method for the LLC LED driver with symmetric primary resonant current and asymmetric primary resonant current has been analyzed in detail. Some design considerations have also been presented. Then, an LLC PSR control circuit has been designed based on the theoretical analysis. Finally, a 48-to-78-V/1.3-A laboratory prototype for the LED driver has been built up, and experimental results show that good output current regulation has been obtained.

Common-Mode Voltage Cancellation for Reducing the Common-Mode Noise in DC–DC Converters

Common-mode (CM) noise cancellation method is an attractive approach to reduce the original CM noise in power converters, which helps to shrink the size of electromagnetic interference filter. Traditional CM noise cancellation method cancels the CM noise current by adding a branch consisted of a compensation voltage source and a compensation capacitor, which generates a cancellation current and nullifies the noise current. As the duality, the voltage cancellation method is also feasible for reducing the CM noise, which has not been investigated in dc–dc converters. In this article, a common-mode voltage cancellation (CMVC) method is proposed, which cancels the CM voltage of the converter by inserting compensation voltage source into the input power cord. The requirement for achieving CMVC is that the cancellation voltage and the parasitic capacitances in the circuit are matched. The applications of CMVC method in basic nonisolated and isolated dc–dc converters are presented, and the considerations for practical applications of this method are discussed. Finally, a buck converter and a half-bridge LLC resonant converter prototype are built, and the proposed method is verified by experiment, respectively.

Exploiting Spatial–Temporal Joint Sparsity for Underwater Acoustic Multiple-Input–Multiple-Output Communications

Multiple-input–multiple-output (MIMO) system offers a promising way for high data rate communication over bandwidth-limited underwater acoustic channels. However, MIMO communication not only suffers from intersymbol interference, but also introduces the additional co-channel interference, which brings challenge for underwater acoustic MIMO channel estimation and for channel equalization. In this article, we propose novel interference cancellation (IC) methods for handling this co-channel interference problem in the design of both channel estimation and channel equalization. Our method for channel estimation utilizes the spatial joint sparsity and the temporal joint sparsity in the multipath structure to estimate sparse channels with common delays under distributed compressed sensing framework. In this way, we enhance channel estimates with common delays, thus, suppress co-channel interference. Meanwhile, to address the case of multipath arrivals with different delays, which are estimated as noise under simultaneous orthogonal matching pursuit (SOMP) algorithm, we introduce forward–reverse strategy to SOMP algorithm, which is referred to as the FRSOMP algorithm. Our proposed FRSOMP algorithm performs the SOMP algorithm to achieve the initial channel estimates, performs the forward-add process, which attempts to add promising candidates into support sets, and performs the reverse-fetch process to check if the candidates in the support set are retained or removed. The purpose of channel estimation is to directly calculate the filter coefficients for channel-estimation-based decision feedback equalization (CE-DFE). In this article, we also propose a novel CE-DFE receiver with IC component. We design IC filters based on the traditional CE-DFE, and we derive the coefficients of the feedforward filters, feedback filters, and IC filters based on the channel estimate metric obtained by the FRSOMP algorithm, so the co-channel interference will be suppressed both in channel estimation and channel equalization. We demonstrate the performance of our approach by numerical simulation, lake experiment, and sea experiment. Results are provided to demonstrate the effectiveness of the proposed methods, which show that the proposed methods obtain higher output signal-to-noise ratio, lower bit error rate, and more separated constellations compared with the traditional compressed sensing channel estimation method and the traditional CE-DFE method.

Design Analysis of Inductorless Active Loaded Low Power UWB LNA Using Noise Cancellation Technique

AbstractThis paper includes a design analysis of an inductorless low-power (LP) low-noise amplifier (LNA) with active load for Ultra Wide Band (UWB) applications. The proposed LNA consists of two parallel paths, one is the common source (CS) path and second is the CG path. The CG path has the edge advantage of improving overall Noise figure (NF) due to wide band impedance matching in UWB, while the CS path provides high power gain. A method for noise cancellation is adopted, to reduce the noise of CS path with the help of CG path. The proposed LNA successfully simulated in 90 nm CMOS technology. The results of proposed work indicate optimization at frequency 5.70 GHz with 3 dB bandwidth of 4.3 GHz–8.9 GHz. All simulations have been done for a range of frequency 03 GHz–13 GHz in Cadence virtuoso software. The results quoted 1.15 dB NF, −18.12 dB S11, 13.7 dB S21, maximum operating power gain (GP) 11.756 dB at frequency 5.7 GHz and available power gain (GA) is 10.17 dB at frequency 8.61 GHz, with 0.6 V, 0.92 mW broad band LNA.

High-Gain High-Efficiency IPOS LLC Converter With Coupled Transformer and Current Sharing Capability

In this paper, an input-parallel output-series (IPOS) LLC resonant converter with a coupled transformer and current sharing capability is proposed for high-gain high-efficiency applications such as the renewable energy grid connection. The coupled transformer is utilized to reduce the core size and core loss by implementing the magnetic flux cancellation method, which achieves a natural balance of output voltage simultaneously. The current sharing between the converter modules is achieved by a bridge wire that interconnects the resonant tanks of different modules. Furthermore, the current sharing inside a module is also achieved by the proposed compensation current based on the coordination of compensation inductor and delay control. A 200 kHz 100 V/1.2 kV 3.6 kW two-module IPOS LLC resonant converter prototype is built to verify the proposed method. The peak efficiency can reach as high as 97.5%, and the current sharing between modules and inside a module are well presented.

New Side Lobe Cancellation Method of Linear Frequency Modulated Radar Signals

Pulse Compression (PC) technique has many advantages in signal processing of radar systems which enhances the radar performance. For a long pulse, the range detection capability can be increased with PC while maintain the advantage of resolution in range for uncompressed pulse. There are many PC techniques such as Binary and Linear Frequency Modulation (LFM) Codes, which can be utilize in radar. The radar detection performance is affected by unwanted signals, which called side lobes that may mask the weaker useful signals, which are present near to strong signals. Pulse compression that uses LFM code is discussed and contrasted with matched filter keep tracked of Hamming windowing filter technique to eliminate the level effect of side lobes. In the present paper, a proposed optimum filter is introduced to enhance both the radar detection capability and resolution in range. The proposed optimum filter representation is evaluated and compared with the classical matched filter response associated with Hamming windowing filter according to the representation of radar detection through Receiver Operating Characteristics (ROC) curves and resolution performance.

An iterative ITI cancellation method for multi-head multi-track bit-patterned magnetic recording systems

Bit-Patterned Magnetic Recording (BPMR) is one of the emerging data storage technologies, which promises an Areal Density (AD) of about 4 Tb/in2. However, a major problem practically encountered in a BPMR system is Inter-Track Interference (ITI) that can deteriorate the overall system performance, especially at high ADs. This paper proposes an iterative ITI cancellation method for an m-head m-track BPMR system, which uses m heads to read m adjacent tracks and decodes them simultaneously. To cancel the ITI, we subtract the weighted readback signals of adjacent tracks, acting as the ITI signals, from the readback signal of the target track, before passing the refined readback signal to a turbo decoder. Then, the decoded data will be employed to reconstruct the ITI signal for the next turbo iteration. Experimental results indicate that the proposed system performs better than the conventional system that uses one head to read one data track. Furthermore, we also find out that the proposed system is more robust to media noise and track misregistration than the conventional system.