Cancellation Method Research Articles

A New Method for Offline Compensation of Phase Discrepancy in Measuring the Core Loss With Rectangular Voltage

Nowadays accurate characterization of the magnetic component losses becomes increasingly important in the design stage of power converters. As the main challenge in characterizing a magnetic component, the core loss is commonly measured through the two winding B-H loop measurement method that is susceptible to the phase discrepancy error, especially for low-permeability, low-loss cores. This paper, therefore, proposes a new offline method to compensate the phase discrepancy error in high-frequency core loss measurement under rectangular voltage excitation. In the post-processing of measured waveforms, the phase discrepancy is compensated by shifting the measured current horizontally to align with a reference phase angle, which is found from an offline impedance sweep on the component-under-test and FFT analysis. As a result, the testing voltage and current waveforms can be measured without considering deskew at the time of measuring. Additionally, this method is more accurate than calibration methods considering a fixed frequency response (e.g., a deskew fixture), because it considers the frequency response across the whole spectrum. The proposed approach can be well applied for typical PWM converters with switching frequencies up to hundreds of kilohertz, for which the effective voltage harmonics extend to a few megahertz range that can be well evaluated with an impedance analyzer. The presented method is experimentally verified against the existing partial cancellation method which is immune to phase discrepancy error.

Channel Estimation Based on Interference Cancellation Method for FBMC-PON

Based on the traditional orthogonal frequency division multiplexing passive optical network (OFDM-PON) system, filter bank multi-carrier passive optical network (FBMC-PON) eliminates the CP by introducing a prototype filter, dramatically improving spectral efficiency. Meanwhile, thanks to its excellent bit error rate (BER) performance, FBMC-PON becomes one of the significant alternatives to OFDM-PON. In previous practical cases, the interference approximation method (IAM) based channel estimation algorithm, which mainly enhances the power of train sequence, plays superior in FBMC-PON. However, the interference cancellation method (ICM) channel estimation method is a better choice due to the self-cancellation of imaginary interference, especially for short-distance optical fiber access channels. We analyze the different train sequences and consider that in the short fiber channel of PON, it is more vital to suppress the imaginary interference rather than improve the train sequence’s power. The simulation results show that the performance of FBMC-PON based on ICM is one order of magnitude higher than that of OFDM-PON and half an order of magnitude higher than that of IAM in the case of 20km fiber. Our proposed channel estimation algorithm only changes the structure of the train sequence and does not increase any additional computational complexity.

A miniaturized giant magnetic resistance system for quantitative detection of methamphetamine.

Point-of-care testing (POCT) systems have been greatly developed in recent years. Among them, lateral flow immunoassay (LFIA) based on magnetic nanoparticles (MNPs) is widely used in various fields due to the advantages of small background noise and good biocompatibility. This paper designed an ultra-sensitive giant magnetic resistance (GMR) system for the quantitative detection of methamphetamine (MET). The system uses GMRs to detect the distribution of the magnetic field intensity of MNPs captured by the test (T) and control (C) lines on LFIA. A special external interference cancellation (EIC) method and a weak-signal waveform reconstruction method were used to improve the accuracy of the detection. Finally, the T/C ratio was calculated to realize the quantitative detection of MET. The result showed good linear performance with a detection limit of 0.1 ng mL-1. The system can also be used in other fields such as disease detection, food analysis, and environmental testing.

Noise cancellation for continuous wave mud pulse telemetry based on empirical mode decomposition and particle swarm optimization

Mud pulse telemetry (MPT) is the most widely implemented communication method in measurement while drilling (MWD) systems. However, the signal-to-noise ratio of received signals on surface in MPT systems is relatively low because of the various background noises the signals have been exposed to during the drilling process. Due to the reciprocating action of the mud pump, pump noise could be the most detrimental factor to the mud pulse signal. Hence, pump noise cancellation plays an important role in the mud pulse telemetry. This paper presents a novel approach for pump noise cancellation by making use of the optimal signal reconstruction based on the combination of the empirical mode decomposition (EMD) and the particle swarm optimization (PSO). The proposed method comprises the pump noise recovery and the pump noise subtraction. The pump noise recovery is implemented by EMD decomposing the pump noise into a series of subcomponents and by PSO searching for the optimal weights to reconstruct the pump noise. Then the pump noise is subtracted from the received signal. To validate the effectiveness of the proposed method, both simulation tests and field experiment were carried out. The noise cancellation results of the simulation tests showed a good agreement with the modulated signal. In the experiment, the downhole information data was successfully demodulated after the implementation of the EMD-PSO based noise cancellation method. Meanwhile, the proposed method could achieve a lower bit error rate than the pump noise filter method. The findings of this study indicate that the optimal signal reconstruction has a promising application in MPT systems in the future.

Theoretical assessment and application of modern GNSS signals acquisition performance

The application of the Global Navigation Satellite System (GNSS) is extensive and has widely infiltrated the national economy and social development in various fields. As critical part of the satellite navigation system design process, GNSS signals performance assessment has received tremendous attention for a long period of time. The mathematical model of GNSS signal detection is built based on single point detection test. An improved acquisition performance assessment method that considers the modulation type, code search step-size, and acquisition algorithms is proposed herein. This study investigates the performance of the overall detection and main/side peak detection for Binary Offset Carrier (BOC), Multiplexed Binary Offset Carrier (MBOC), and Alternative BOC (AltBOC) signals using matched and unambiguous acquisition methods, and obtains quantitative results. With a fixed code search step-size, the multi-peaks of the autocorrelation functions of BOC, MBOC, and AltBOC signals will degrade the acquisition performance. The higher the sub-carrier rate, the more serious is the degradation. Although signal-power loss occurs to some extent, Binary Phase-Shift Keying-like (BPSK-like) and Sub Carrier Phase Cancelation (SCPC) methods significantly improve the acquisition performance.

An Advanced Non-Orthogonal Multiple Access Security Technique for Future Wireless Communication Networks

The future wireless communication systems demand much more enhanced security and reliability compared to currently deployed systems. In this work, we propose a much simpler yet more efficient physical layer security (PLS) technique for achieving reliable and secure communication in the multiple-input single-output non-orthogonal multiple access (MISO-NOMA) systems. This system is capable of providing enhanced confidential communication as well as inter-user interference cancellation without using the successive interference cancellation (SIC) method. The conventional NOMA was previously adopted under the name of multi-user superposition transmission (MUST) in release 13 of 3GPP but recently excluded from 3GPP-release 17 due to its performance degradation. In this work, we analyze the drawbacks in conventional NOMA and present a new kind of NOMA with more improved performance metrics. The proposed algorithm combines the benefit of pre-coder matrices with simultaneous transmission using antenna diversity to provide simple, reliable, and secure communication without complex processing at the receivers in downlink scenarios. The effectiveness of the proposed algorithm is verified and proven by extensive analysis and numerical simulations.

Self-adaptive query-broadcast in wireless ad-hoc networks using fuzzy best worst method

Various broadcasting schemes have been proposed for a unified routing approach in Wireless Adhoc Networks. In their efforts, the researchers mostly aim to minimize the routing-overheads including overfilling of query, routing delay and energy-drain. The routing overheads are minimized using either repeated broadcast or canceling the query-broadcast. On one hand broadcast cancellation methods work based on query-chasing, which creates an extra routing-overhead. On the other hand routing cache based query-broadcast techniques are not adaptive with mobility of target nodes giving rise to unreachability problem. Both types of approaches pose the increased energy-drain and ultimately slow down the route-discovery . These limitations in particular, have motivated us to propose a dynamic request-zone approach for query-broadcasting based on routing-cache. In order to counter the destination unreachability problem, a combined weight metric is used, which is defined as a multi-criteria decision making problem. Later defined problem is solved to compute the weights using extended fuzzy best-worst method. Furthermore the performance of proposed approach is evaluated in terms of query-diffusion, route-latency, and energy-saving.

NOMA-aided generalized pre-coded quadrature spatial modulation for downlink communication systems

Generalised pre-coding quadrature spatial modulation (GPQSM) is recently proposed to increase the spectral efficiency (SE) of GPSM, which extends the transmitted symbols into in-phase/quadrature domains. In this paper, a novel scheme named non-orthogonal multiple access (NOMA)-aided GPQSM (NOMA-GPQSM), which incorporates the GPQSM scheme into the multi-user communication networks with assist of NOMA, is proposed to further improve the SE and system performance. In NOMA-GPQSM, one base station (BS) is set to serve K users, where user 1 is closest to the BS, and user K is farthest from the BS. In addition, a low-complexity detection method is proposed to reduce the high detection complexity of the maximum-likelihood (ML) detection in successive interference cancellation (SIC) method for all users by NOMA-GPQSM. The theoretical analysis of the BER performance for all users is also derived. Simulation results show that near users achieve relatively good performance, and far users achieve acceptable performance by adjusting power factors for all users in NOMA-GPQSM.

EMI Noise Reduction of DC-DC Switching Converters with Automatic Output Ripple Cancellation

This paper proposes new EMI reduction technologies and automatic output voltage ripple cancellation method for the PWM buck converter with voltage-mode or current-mode and the ripple-controlled converters. Genenrally, modfying the clock frequeny is effective to reduce the EMI noise, but it may increase the output ripple substantially. We have developed techniques to cancel the increased ripple by modifying the slope of the saw-tooth signal or current of the ripple injection circuit. The EMI spectrum of the operating frequency is reduced by more than 15dB and the modified large ripple is canceled to the stable level.

Searching for anomalous polarization modes of the stochastic gravitational wave background with LISA and Taiji

The vector and scalar polarization modes of gravitational waves do not exist in General Relativity, and their detection would have significant impacts on fundamental physics. In this paper, we explored the detectability of these anomalous polarization modes in a gravitational wave background around 1 mHz with the future LISA-Taiji network. The inherent geometrical symmetry of the network largely simplifies the correlation analysis. By taking a suitable linear combination of the correlated outputs, the contribution of the standard tensor modes can be canceled algebraically, and the anomalous modes can be exclusively examined. We provide concise expressions for the signal-to-noise ratios of the anomalous modes with this cancellation method. We also discuss the possibility of separately estimating the amplitudes of the vector and scalar modes, using the overall frequency dependence of the associated overlap reduction functions.

Decoupling Between Extremely Closely Spaced Patch Antennas by Mode Cancellation Method

In this article, an inductance-based decoupling scheme is proposed to reduce the mutual coupling between extremely closely spaced microstrip antennas. The original strong coupling can be effectively suppressed by simply inserting a lumped inductance in between. To offer a systemic design guideline for this decoupling strategy, a mode cancellation method, based on the synthesis of common mode (CM) and differential mode (DM), is proposed. The inserted inductance plays a role of tuning CM and DM impedances to a similar status, which has an equivalent decoupling effect according to the theory of microwave network. Alternatively, the lumped inductance could also be replaced by an inductive connecting strip for a concise topology. To validate the proposed decoupling concept, a prototype is simulated, fabricated, and measured. The experimental results show that the poor isolation of 5 dB is improved to better than 15.4 dB across the entire matched bandwidth of 2.394-2.530 GHz, with an extremely close edge-to-edge distance of 0.016 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> and center-to-center distance of 0.44 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> . Furthermore, the validation of extending to large-scale 1-D and 2-D arrays is also discussed. Featuring simple structure, compressed dimension, strong-coupling suppression, and good radiation performance, the proposed decoupling scheme possesses promising potential for antenna array applications.

PK-Yay: A Black-Box Method Using Density Functional Theory and Implicit Solvation Models to Compute Aqueous pKa Values of Weak and Strong Acids.

The concept of pKa is very important in chemistry and biology. Over the past two decades, electronic structure calculations have made huge strides toward becoming reliable counterparts to experiments in determining solution-phase pKa values. However, invariably, the computation of pKa values involves the use of methods whose error bars are intrinsically larger (definitely >2 kcal/mol with density functionals) than the accuracy desired for the estimation of pKa values (<1 or 1.5 pKa units). This scenario presents an ample scope for innovation in developing systematic error cancellation methods even today. In this work, we have developed the pK-Yay method. It is a user-friendly black-box method used to compute aqueous pKa values of strong and weak acids employing routinely used and computationally inexpensive density functionals and implicit solvation models. It does not require the use of any explicit solvent molecule or modifying any other parameter in an electronic structure program. As part of evaluating the method, a comprehensive test set of 26 weak and strong organic and mineral acids covering 35 pKa units (20 to -15) was assembled. The detailed description of the method, its performance with different functionals (ωB97X-D performed best for organic acids with a mean absolute error (MAE) of 0.8 pKa units, and B2-PLYP performed best for strong acids with an MAE of 1.6 pKa units), the strengths and limitations in the present version, and a future scope to improve the accuracy and reduce its empirical nature are presented herein.

A 40 nm 16 Gb/s differential transmitter with far-end crosstalk cancellation using injection timing control for high-density flexible flat cables

In some long-reach high-density wires such as flexible flat cables, the crosstalk signal from the aggressor to the victim lanes exhibits the time shift that depends on the cables. This paper proposes a far-end crosstalk (FEXT) cancellation method with controllable injection timing of the crosstalk cancellation (XTC) signals into the victim lanes. The proposed method uses a delay-line-based digital-to-time converter for delay tuning and generates the XTC signals at the transmitter, then inject it to cancel the FEXT effectively on these cables. The proposed XTC circuit is implemented in the differential transmitter so that the XTC signal is generated from the digital data signal from the aggressor. The transmitter circuit with the proposed XTC technique is designed in a 40 nm bulk CMOS process, and its feasibility is verified through the post-layout simulation at a data rate of 16 Gb/s.

Passive Intermodulation in Simultaneous Transmit–Receive Systems: Modeling and Digital Cancellation Methods

This article presents novel solutions for suppressing passive intermodulation (PIM) distortion in frequency-division duplexing (FDD)-based radio transceivers, stemming from nonlinear radio frequency (RF) components and simultaneous transmission and reception, with special emphasis on modern carrier aggregation networks. With certain transmission band combinations in, e.g., long-term evolution (LTE) or the emerging 5G new radio (NR) mobile radio systems, the nonlinear distortion produced by the passive components of the transceiver RF front end can result in intermodulation (IM) distortion that falls within one of the configured reception bands. While the traditional solution to mitigate this problem is to reduce the transmit power, we take an alternative approach and seek to cancel such PIM in the transceiver digital front end by using the original transmit data as a reference. To generate as accurate cancellation signal as possible, we derive different advanced signal models for the observable IM distortion at own receiver band that incorporates also the power amplifier (PA) nonlinearities, together with the passive component nonlinearities and the frequency-selective responses of the duplex filters. The performance and the processing complexity of the devised digital cancellation and parameter estimation solutions are evaluated with real-life RF measurements, where an actual LTE-Advanced user equipment (UE)-type transceiver system is utilized. The obtained results show that the proposed cancellers are implementation feasible and can suppress the self-interference by over 20 dB, canceling the distortion nearly perfectly up to UE transmit powers of +24 dBm. The results also indicate that, in many cases, it is necessary to model the nonlinear distortion effects produced by the PAs, even if the individual component carriers are combined after the amplification stage.

Processing of Underground Nuclear Magnetic Resonance Data for Underground River Detection: A Case Study in Doumo Tunnel, Guizhou, China

Underground nuclear magnetic resonance (NMR) is introduced to detect the risk of groundwater-induced disasters in the underground engineering such as tunnels and mines. However, underground NMR is in practice often limited to the extremely low signal-to-noise ratios (SNRs). On the one hand, small coils are necessary to be used to detect water in the narrow underground space, which decreases the amplitude of the excited signal. On the other hand, the weak signal is submerged in quite serious electromagnetic noise which is generated from the electrical installations. The low SNRs emphasize the importance of using an optimal post-processing strategy to obtain the reliable underground NMR data. The objective of this paper is to explain the processing of underground NMR data taking the detection of the underground river in Doumo Tunnel as an example. We have evaluated the noise condition in Doumo Tunnel and the noise level of 0.6760 nV/m2 was found in this area. At such a high noise level, the reliable underground NMR signal is difficult to be extracted and the credible depth profile of water content is unable to be provided. Then, we have analyzed the noise interference. Although de-spiking algorithm and reference-based noise cancellation method were applied to remove the major noise sources, the underground NMR signal is still invisible. There is still a lot of additive noise remained, so time-frequency peak filtering method is further used to suppress the remaining noise. The performance of the proposed post-processing strategy is tested on the underground NMR data from the underground river. The result was consistent with the geological structure, which is demonstrated to be able to directly provide a security pre-warning of the underground engineering.

Design of Time-Frequency Packed WDM Superchannel Transmission Systems

We consider time and frequency-packing (TFP) wavelength division-multiplexing (WDM) superchannel systems for longhaul optical fiber communication. Employing very high baud rates in conjunction with higher-order modulation formats is challenging due to practical constraints. TFP superchannels therefore become an attractive choice to facilitate high data rates with improved spectral efficiency. However, TFP introduces inter-symbol interference (ISI) and/or inter-carrier interference (ICI) that necessitate efficient interference handling techniques. Moreover, phase noise (PN) due to wide laser linewidth (LLW) may cause significant signal distortion in WDM transmission, and the presence of ISI and ICI in TFP systems further complicates carrier phase recovery (CPR). In this article, we propose a spectrally efficient TFP superchannel design equipped with powerful interference cancellation and PN mitigation techniques, targeting Terabit-per-second (Tbps) data rates. First, we propose a joint ISI and ICI channel estimation algorithm coupled with polarization-recovery and a coarse PN cancellation method. Second, we investigate two iterative CPR algorithms to mitigate the distortion due to the residual PN. Third, a combination of successive and parallel interference cancellation methods for ICI mitigation is investigated in tandem with turbo ISI equalization. The effectiveness of the proposed algorithms is demonstrated through computer simulations of a coded TFP superchannel system in the presence of linear fiber impairments, targeting a throughput of 1.2 Tbps. Numerical results suggest that the proposed TFP design offers more than 2 dB performance gains and as high as 960 km transmission distance improvement over existing competitive super-Nyquist designs. Simulation results also indicate that the proposed design exhibits excellent tolerance to high LLWs and aggressive optical filtering stemming from cascaded reconfigurable optical add-drop multiplexers in the fiber link.

Performances of OSIC Detector of an UpLink OFDM Massive-MIMO System in Rayleigh and Ricain Fading Channels

This paper presents a least squares channel estimation for Massive-Multiple-Input Multiple- Output (Massive-MIMO) systems in next generation of wireless communications denominated 5G, combined with Orthogonal Frequency Division Multiplexing (OFDM) and 64-QAM modulation. In this paper, after determining the estimated channel, we first consider one OFDM symbol and presented the flat fading and the frequency-selective fading in the case when channel taps equal to one and strictly superior to one respectively. In addition to that, we consider the uplink transmission where the transmitter antenna equal to $$N_t=50$$ and a Base Station (BS) equipped with several antenna superior to that of transmitter, in the same way the data detected using a linear detectors Zero-Forcing and Minimum Mean Square Error. Moreover we improve their performance by an ordered successive interference cancellation (OSIC) method. Using two channels fading namely the Rayleigh and the Ricain respectively and evaluate their performance with a system of Massive-MIMO antenna. Increasing the number of channel taps increase the inter-symbol interference allows to degrade the performance of the system both the Rayleigh and Rician channel, even we used a pilot sequence equipowered, equispaced and phase shift orthogonal. Hence increasing the number of antennas arrays at the receiver (i.e BS) decreases more the Bit Error Rate, consequently increasing the performance of the system. the OSIC methods provide a best performance when the number of antenna grow in a smaller range of Signal-to-Noise Ratio.

Hawking flux from a black hole with nonlinear supertranslation hair

We study the Hawking flux from a black hole with soft hair by the anomaly cancellation method proposed by Robinson and Wilczek. Unlike the earlier studies considering the black hole with linear supertranslation hair, our study takes into account the supertranslation hair to the quadratic order, which then yields the angular dependent horizon. As a result, highly nontrivial kinetic-mixings appear among the spherical Kaluza-Klein modes of the (1+1)d near-horizon reduced theory, which obscures the traditional derivation of the Hawking flux. However, after a series of field re-definitions, we can disentangle the mode-mixings into canonical normal modes, but the reduced metrics for these normal modes are mode-dependent. Despite of this, the resultant Hawking flux turns out to be mode-independent and remains the same as the Schwarzschild's one. Thus, one cannot tell the black holes with nonlinear supertranslation hairs from the Schwarzschild's one by examining the Hawking flux, so that the nonlinear soft hairs can be thought as the microstates.

Two‐stage clutter and interference cancellation method in passive bistatic radar

Target echoes are inevitably contaminated by the direct-path signal, multipath signal and possible interference in passive bistatic radar (PBR). Cancellation performance is deteriorated as the interference signal is irrelevant to the transmitted signal and the target echoes are submerged by in the sidelobe of the spread clutter echoes. In this study, the cancellation problem is addressed, involving clutter and interference. In this method, the spread clutter echoes are cancelled by constructing a tailored clutter subspace. Besides, the interference is also cancelled by constructing a tailored interference subspace. The sample of the interference signal is obtained from the beam channel after clutter cancellation. The performance of the proposed method is first verified by the simulation result. Then its effectiveness is also demonstrated with the application of the real data collected from an experimental PBR system.

Motion artifact cancellation from a single channel SCG using adaptive forgetting factor recursive least square filter

This work proposes a novel filter for motion artifact cancellation from a single channel seismocardiography (SCG) data recorded by a tri-axis accelerometer. A real time adaptive forgetting factor recursive least square filter (AFFRLSF) was developed and embedded in our designed single channel SCG recorder system (SCSRS) for motion artifact cancellation, heartbeat signal extraction, and heart rate calculation. This SCSRS was placed on the chest wall of 24 subjects who were asked to perform standing, walking, jogging, and jumping movements on a treadmill. We recorded the single channel SCG signal and the standard Electrocardiogram (ECG) lead I signal by placing one electrode on the right arm (RA) and another on the left arm (LA) of the subjects. The heartbeat signals were extracted and heart rates were calculated from the output of AFFRLSF. The graphs of the extracted heartbeat signals were very clear under all the standing, walking, jogging, and jumping motions. The results indicate an average correlation coefficient of up to 0.9878 between heart rates estimated from SCG and ECG of all the 24 subjects. This observation shows that the proposed AFFRLSF could be an effective method for motion artifact cancellation from recorded single channel SCG signals.