Two-electrode biopotential measurements: power line interference analysis

In this paper, an analysis of power line interference in two-electrode biopotential measurement amplifiers is presented. A model of the amplifier that includes its input stage and takes into account the effects of the common mode input impedance Z(C) is proposed. This approach is valid for high Z(C) values, and also for some recently proposed low-Z(C) strategies. It is shown that power line interference rejection becomes minimal for extreme Z(C) values (null or infinite), depending on the electrode-skin impedance's unbalance deltaZ(E). For low deltaZ(E) values, minimal interference is achieved by a low Z(C) strategy (Z(C) = 0), while for high deltaZ(E) values a very high Z(C) is required. A critical deltaZ(E) is defined to select the best choice, as a function of the amplifier's Common Mode Rejection Ratio (CMRR) and stray coupling capacitances. Conclusions are verified experimentally using a biopotential amplifier specially designed for this test.     

An improved adaptive power line interference canceller for electrocardiography

Power line interference may severely corrupt a biomedical recording. Notch filters and adaptive cancellers have been suggested to suppress this interference. We propose an improved adaptive canceller for the reduction of the fundamental power line interference component and harmonics in electrocardiogram (ECG) recordings. The method tracks. the amplitude, phase, and frequency of all the interference components for power line frequency deviations up to about 4 Hz. A comparison is made between the performance of our method, former adaptive cancellers, and a narrow and a wide notch filter in suppressing the fundamental power line interference component. For this purpose a real ECG signal is corrupted by an artificial power line interference signal. The cleaned signal after applying all methods is compared with the original ECG signal. Our improved adaptive canceller shows a signal-to-power-line-interference ratio for the fundamental component up to 30 dB higher than that produced by the other methods. Moreover, our method is also effective for the suppression of the harmonics of the power line interference.     

Pacemaker interference by magnetic fields at power line frequencies

Human exposure to external 50/60-Hz electric and magnetic fields induces electric fields within the body. These induced fields can cause interference with implanted pacemakers. In the case of exposure to magnetic fields, the pacemaker leads are subject to induced electromotive forces, with current return paths being provided by the conducting body tissues. Modern computing resources used in conjunction with millimeter-scale human body conductivity models make numerical modeling a viable technique for examining any such interference. In this paper, an existing well-verified scalar-potential finite-difference frequency-domain code is modified to handle thin conducting wires embedded in the body. The effects of each wire can be included numerically by a simple modification to the existing code. Results are computed for two pacemaker lead insertion paths, terminating at either atrial or ventricular electrodes in the heart. Computations are performed for three orthogonal 60-Hz magnetic field orientations. Comparison with simplified estimates from Faraday's law applied directly to extracorporeal loops representing unipolar leads underscores problems associated with this simplified approach. Numerically estimated electromagnetic interference (EMI) levels under the worst case scenarios are about 40 microT for atrial electrodes, and 140 microT for ventricular electrodes. These methods could also be applied to studying EMI with other implanted devices such as cardiac defibrillators.     

Coexistence of broadband power line communication systems

es and the radiation field are finally determined.     

直扩超宽带信号在移动通信系统中的干扰功率分析

对直扩超宽带(DS UWB)信号分别于时域和频域进行描述,并对其功率谱密度进行了详细研究.在干扰功率计算中,选择现有3G移动标准宽带码分多址(WCDMA)、码分多址2000(CDMA2000)和时分同步码分多址(TD SCDMA)作为被干扰系统.与UWB信号带宽相比,被干扰系统的带宽相对较窄,因此假设在接收端频谱是平坦的.研究结果表明,可以通过调整DS UWB脉冲波形和脉冲成形因子α来减少干扰功率.通过权衡和比较,脉冲成形因子小于0.3 n s的三阶高斯脉冲是一个最优选择     

A nonlinear adaptive method of elimination of power line interference in ECG signals

A new method of elimination of power line noise in electrocardiogram signals is presented. The proposed method employs, as its main building block, a recently developed signal processing algorithm capable of extracting a specified component of a signal and tracking its variations over time. Design considerations and performance of the proposed method are presented with the aid of computer simulations. Superior performance is observed in terms of effective elimination of noise under conditions of varying powerline interference frequency. The proposed method presents a simple and robust structure which complies with practical constraints involved in the problem such as low computational resource availability and low sampling frequency.     

共道干扰下多入多出系统功率分配最优化问题

多输入多输出(MIMO)技术可以极大地提高系统容量和频带利用率,是下一代移动通信网和宽带无线网络的核心技术。在实际情况中,尤其是在多用户情况下,MIMO链路间存在的共道干扰将会对其容量性能产生严重影响,此时需要对MIMO系统功率分配方案进行优化设计。给出了共道干扰MIMO系统的信号模型,从最大化互信息角度分析共道MIMO系统容量,提出在干扰噪声比-信噪比(R_IN-R_SN)空间将系统优化问题归为4种情况,并给出可行的功率分配优化方案,同时分析了方案的适用性,指出亟待解决的主要问题和进一步的研究方向。     

抑制OFDM系统载波间干扰的sinc功率脉冲优化

针对由多普勒扩展和收发机本振频率漂移引起的OFDM系统载波频率偏移从而导致子载波间干扰的问题,提出了一个抑制OFDM系统载波间干扰的sinc功率脉冲优化方法。该方法以sinc功率脉冲为基础,通过优化参数对旁瓣电平进行优化,以降低OFDM系统载波间干扰的强度。仿真结果表明,与sinc功率脉冲相比,采用优化的sinc功率脉冲的OFDM系统更能适应高速移动环境,当归一化频偏为0.3、误比特率等于10-5时,采用新方法的OFDM系统可获得约3 dB性能的提升。     

Wavelet-based OFDM-CDMA high speed power line communication systems

This letter derives the Equivalent M-band Discrete Wavelet(EMDW) transmission mode of Orthogonal Frequency Division Multiplexing(OFDM) transmission systems, and presents a new Quadrature M-band Discrete Wavelet(QMDW) based OFDM-CDMA(Code Division Multiple Access) communication systems for high speed Power Line Communication (PLC) channels,This system gives much better robustness to Inter-Channel Interference (ICI), Multi-User Interference (MUI) and noise interference, which is verified by simulation.     

An adaptive canceller of cochannel interference for spread-spectrummultiple-access communication networks in a power line

The authors propose and investigate an adaptive canceller of intersymbol and cochannel interference due to channel distortion and cross-correlation among pseudonoise sequences assigned to individual users of a DS-SSMA (direct-sequence spread-spectrum multiple-access) system. In order to implement a local area network (LAN) by using a power line installed in a building wall as a transmission channel, the authors have investigated utilization of DS-SSMA which has advantages such as robustness against narrow-band interference and noise and realization of asynchronous code division multiple access. In a power line, however, restriction of transmission bandwidth for communications makes it difficult to suppress cochannel interference and the channel is also time-varying due to fluctuation of loads. Since the proposed canceller adaptively eliminates cochannel interference as well as intersymbol interference, it can facilitate synchronization and increase the number of the simultaneously accessing users on a power line with restricted processing gain. The error probability in the output of the canceller is theoretically calculated for the steady-state case by using a Markov model. Computer simulations illustrate stable convergence properties of the canceller     

一种抑制低压电力线载波通信干扰的方法

以低压电力线作为媒介进行数据传输时,提高其传输的可靠性对低压电力线载波通信有重要意义。针对低压电力线信道所具有的时变性和强干扰性,提出了新的抗干扰方案,即采用卷积码直接序列扩频通信方案,并使用MATLAB对该方案的抗干扰性能进行了仿真验证。结果表明,该方案能较好地抑制低压电力线信道中的干扰,满足低压电力线通信要求。     

High power broadcasting skywave transmitters interference analysisfor navigation and communication systems

The operation of high-power broadcasting transmitters (Tx) can strongly interfere with collocated and even remote radio communication and navigation systems on broad frequency ranges. In these cases, extensive analysis and computation method developments are essential in order to assess the feasibility of reliable operation of indispensable radio communication links. The magnitudes of the interference effects are computed, based on specifications of 500 kW skywave Tx parameters and the important airborne VHF radio navigation and communication systems. The critical interference (i.e. desensitization or blocking of the victim airborne receivers) and other interference modes are analyzed using semiempirical state-of-the-art computation methods. Limits for victim receiver distances and frequency intervals for no-interference situations and optimal reception conditions are obtained     

传输线的反射干扰

在数字信号处理系统中,时钟信号和数字信号传输因传输始端和终端阻抗不匹配而引起反射干扰,使传输信号的波形出现上冲、下降和振荡。为了抑制这种因阻抗不匹配引起的反射,本文首先从产生这种反射的原因和造成的重大危害分析,提出了反射干扰这一亟待解决的问题;接着从传输线的阻抗特性以及阻抗匹配原理出发,提出了始端和终端阻抗匹配原则,最后给出了几种减小和抑制反射干扰的方法,实践证明使用阻抗匹配这一方法在减小反射干扰是十分有效的。     

Broadband PLC access systems and field deployment in European power line networks

Data communications over low voltage power distribution networks provide an alternative and cost-effective last mile access technology. It offers data and voice services to users in residential and business areas. Currently, many field trials with different broadband power line communications systems are running worldwide. This article describes one of these systems for the last mile application in European power line networks. It addresses major field deployment aspects, such as range, coverage, coupling, and intercell interference.     

Intersymbol interference in duobinary systems

An upper bound for the error probability due to intersymbol interference and Gaussian noise is calculated for duobinary signalling systems. The duobinary system with twice the binary signalling speed has an error rate in excess of that of a binary system using identical filters.     

一种改进的电力线通信系统脉冲噪声抑制方法

为了抑制脉冲噪声对电力线正交频分复用（OFDM）通信系统的影响,最常用的方法之一是在接收端OFDM解调器之前前置一个置零非线性单元,即传统置零法。然而,由于引入了非线性失真,其性能并不理想。针对传统置零法引起的非线性失真问题,提出了一种基于迭代消除非线性失真的改进置零法。首先,对接收到的时域OFDM信号进行脉冲噪声检测和置零处理;然后,在频域利用已检测的符号来重构时域置零处理引入的非线性失真,并通过迭代提高重构的准确性;最后,从频域接收信号中减去重构的非线性失真。仿真结果表明,所提改进算法与传统置零法相比,有非常大的性能提升,增强了电力线OFDM通信系统对脉冲噪声的抵抗能力。     

Broadband hybrid model for relay-aided cooperative MIMO power line communication systems

A hybrid model for broadband multiple-input multiple-output (MIMO) relay-aided indoor power line communications (PLC) system was proposed in this paper. The proposed model combines the top-down and bottom-up approaches and extends to a two-hop relay-aided cooperative system with variable gain relay in amplify-and-forward (AF) mode. Based on the proposed PLC model and generated channel, the channel statistical characteristics are further investigated in 2MHz - 100MHz bandwidth. Simulated results show that the proposed model overcomes the difficulties that the existing models need a lot of topological information of the network or measurements information. It provides a practical simulation analysis method for cooperative relay MIMO-PLC system. The results also show that cooperative MIMO relaying communications can improve the indoor PLC performances and communication reliability.     

Low-complexity uplink scheduling algorithms with power control in successive interference cancellation based wireless mud-logging systems

Wireless Networks - Wireless mud-logging systems have been employed in petroleum exploration to guarantee efficiency and safety in well-drilling. For the wireless networks in well-drillings, the...     

Compressive sensing power control for interference management in D2D underlaid massive MIMO systems

This paper introduces a sparsity controlled multiple random access scheme for efficient user scheduling in Device-to-Device (D2D) underlaid massive MIMO systems. In order to both avoid collision and enhance the Energy Efficiency (EE) of two-tier Heterogeneous Cellular Networks (HCNs), a unified Compressed Sensing (CS) based interference management strategy is proposed which guarantees concurrent cellular and D2D multi-user transmissions without collision. Specifically, supposing the natural sparsity in practical fifth generation (5G) scenarios and employing the sparse signal processing techniques, an analytical random access based model is adopted where provides several user scheduling and channel gain constraints to permit user identification, channel estimation and data decoding simultaneously. Furthermore, by developing a tractable tradeoff between the total power consumption and overall throughput of D2D tier, the transmission power is optimized such that the EE of D2D tier is maximized. Numerical simulations demonstrate the effectiveness of suggested approach to improve the collision avoidance capability and EE of D2D underlaid massive MIMO systems, even for crowded scenarios where the sparsity constraint does not meet sufficiently.