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China Communications 2019年第9期16卷 165-176页

作者： Xiaqing Miao Lu Tian School of Information and Electronics Beijing Institute of TechnologyBeijing 100081China China Academy of Electronics and Information Technology Beijing 100041China

Passive intermodulation(PIM)interference urgently needs to be solved in the satellite communication system,owing to degrading the whole performance.Mainstream research contributions to the Cancellation method for PIM were focused on the analog domain,however,the PIM distortion cannot be eliminated completely with the approaches.Meanwhile,some researchers attempt to tackle the problem through digital signal processing,nevertheless,the proposed methods were not suitable for the practical satellite communication scenario.In this paper,we present a general scheme for the adaptive feedforward PIM Cancellation.High-order PIM signals at baseband are estimated by modeling the PIM distortion with Hammerstein model in the digital domain.Based on the reconstructed PIM signal,we adopt the least mean square algorithm to adaptively mitigate the PIM interference for tracking the variation of PIM.The time and frequency synchronization of PIM are based on the correlation of the peak of received signals with the corresponding reconstructed PIM signal.Practical experimental results show that the scheme can effectively cancel the PIM interference,and achieve an interference suppression gain more than 20dB.

关键词： satellite communication passiveintermodulation interference digital Cancellation Hammerstein model

Approach to MAI Cancellation for micro-satellite clusters

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Journal of Systems Engineering and Electronics 2019年第5期30卷 823-830页

作者： HUANG Jiajun ZHANG Chaojie JIN Xiaojun Micro-Satellite Research Center Zhejiang University

With the development of micro-satellite technology,traditional monolithic satellites can be replaced by micro-satellite clusters to achieve high flexibility and dynamic reconfiguration capability.For satellite clusters based on the frequency division-code division multiple access(FD-CDMA)communication system,the inter-satellite ranging precision is usually constrained due to the influence ofmulti-address interference(MAI).Themulti-user detection(MUD)is a solution to MAI,which can be divided into two categories:the linear detector(LD)and the non-linear detector(NLD).The general idea of the LD is aiming to make a better decision during the symbol decision process by using the information of all channels.However,it is not beneficial for the signal phase tracking precision.Instead,the principle of the NLD is to rebuild the interference signal and cancel it from the original one,which can improve the ranging performance at the expense of considerable delays.In order to enable simultaneous ranging and communication and reduce multi-node ranging performance degradation,this paper proposes an NLD scheme based on a delay locked loop(DLL),which simplifies the receiver structure and introduces no delay in the decision process.This scheme utilizes the information obtained from the interference channel to reconstruct the interference signal and then cancels it from the original delayed signal.Therefore,the DLL input signal-to-interference ratio(SIR)of the desired channel can be significantly improved.The experimental results show that with the proposed scheme,the standard deviation of the tracking steady error is decreased from 5.59 cm to 3.97 cm for SIR=5 dB,and 13.53 cm to 5.77 cm for SIR=-5 dB,respectively.

关键词： micro-satellite satellite clusters multi-user detection(MUD) interference Cancellation inter-satellite ranging

Interference Cancellation in Device-to-Device Communications underlying MU-MIMO Cellular Networks

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China Communications 2019年第4期16卷 75-88页

作者： Yiyang Ni Yuxi Wang Hongbo Zhu Jiangsu Key Laboratory of Wireless Communications Nanjing University of Posts and Telecommunications Jiangsu Second Normal University

This paper investigates the device-to-device(D2 D) communication underlaying multi-user multi-input multi-output(MU-MIMO) cellular networks. It is assumed that D2 D users reuse the downlink time-frequency resources of cellular links, and the base station(BS) is assumed to be equipped with multiple antennas. We investigate the ergodic achievable sum rate of the system when the interference Cancellation(IC) precoding strategy is employed at the BS. The distributions of the received signal-to-interference-plus-noise ratio(SINR) for each link are firstly analyzed, and an exact ergodic achievable sum rate of the whole system with closedform expressions is then derived. Furthermore, we present novel upper and lower bounds with simpler expressions, which are later verified to be fairly close to the Monte-Carlo simulations. All the expressions we presented are suitable for arbitrary network topology and arbitrary number of antennas at BS. Based on the derived bounds, the influence of the antennas at BS on system performance is then analyzed. We reveal that the system performance increases along with the number of antennas at BS in a logarithmic way. The accuracy of our analytical results is validated via comparisons with Monte-Carlo simulations.

关键词： interference Cancellation D2D communication ergodic achievable sum rate MU-MIMO

A conducted emission mitigation method for software-defined radios through vector signal Cancellation

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中国航空学报:英文版 2023年第9期36卷 289-298页

作者： Siyu XIA Qi WU School of Electronics and Information Engineering Beihang UniversityBeijing 100191China

Recently,Software-Defined Radio(SDR)has gained great popularity owing to its attractive merits,such as flexible signals configuration in multiple channels.However,commercial SDR equipment also has large spurious emissions in the Transmitting(Tx)channel.This paper presents a cascaded model for the Conducted Emission(CE)properties of a general SDR platform,which captures all the key components with high precision.Based on a deeper understanding of the CE properties,a mitigation method is proposed for suppressing the spurious emissions of an SDR Tx channel.This method is based on an efficient vector signal Cancellation scheme,in which multiple SDR channels are adopted to suppress the second-and third-order harmonic signals simultaneously.A hardware prototype with dual SDR channels is built and measured for verification.Experimental results show that the suppression level of the third-order harmonic signal is 24 dB on average in the frequency range of 100 MHz to 3000 MHz.The theoretic limit of the suppression level is related to the magnitude and phase errors,and the suppression level may be further improved by calibrating each SDR channel.

关键词： Cancellation Conducted Emission(CE) Harmonic suppression SDR Spurious emission

Noise Cancellation of a multi-reference full-wave magnetic resonance sounding signal based on a modified sigmoid variable step size least mean square algorithm

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Journal of Central South University 2017年第4期24卷 900-911页

作者：田宝凤周媛媛朱慧蒋川东易晓峰 Key Laboratory of Geo-Exploration Instrumentation Ministry of Education (Jilin University)Changchun 130026 China College of Instrumentation and Electrical Engineering Jilin University Changchun 130026 China

Nano-volt magnetic resonance sounding(MRS) signals are sufficiently weak so that during the actual measurement, they are affected by environmental electromagnetic noise, leading to inaccuracy of the extracted characteristic parameters and hindering effective inverse interpretation. Considering the complexity and non-homogeneous spatial distribution of environmental noise and based on the theory of adaptive noise Cancellation, a model system for noise Cancellation using multi-reference coils was constructed to receive MRS signals. The feasibility of this system with theoretical calculation and experiments was analyzed and a modified sigmoid variable step size least mean square(SVSLMS) algorithm for noise Cancellation was presented. The simulation results show that, the multi-reference coil method performs better than the single one on both signal-to-noise ratio(SNR) improvement and signal waveform optimization after filtering, under the condition of different noise correlations in the reference coils and primary detecting coils and different SNRs. In particular, when the noise correlation is poor and the SNR<0, the SNR can be improved by more than 8 dB after filtering with multi-reference coils. And the average fitting errors for initial amplitude and relaxation time are within 5%. Compared with the normalized least mean square(NLMS) algorithm and multichannel Wiener filter and processing field test data, the effectiveness of the proposed method is verified.

关键词： magnetic resonance sounding signal multi-reference coils adaptive noise Cancellation sigmoid variable step size least mean square (SVSLMS)

Adaptive Noise Cancellation Algorithms Implemented onto FPGA-Based Electrical Impedance Tomography System

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Electrical Science & Engineering 2019年第2期1卷 15-25页

作者： Marlin R Baidillah Zengfeng Gao Al-Amin S Iman Masahiro Takei Graduate School of Science&Engineering Dept.Mechanical Eng.Div.Fundamental Eng.Chiba UniversityChiba 263-8522Japan

Electrical Impedance Tomography(EIT)as a non-invasive of electrical conductivity imaging method commonly employs the stationary-coefficient based filters(such as FFT)in order to remove the noise signal.In the practical applications,the stationary-coefficient based filters fail to remove the time-varying random noise which leads to the lack of impedance measurement sensitivity.In this paper,the implementation of adaptive noise Cancellation(ANC)algorithms which are Least Mean Square(LMS)and Normalized Least Mean Square(NLMS)filters onto Field Programmable Gate Array(FPGA)-based EIT system is proposed in order to eliminate the time-varying random noise signal.The proposed method was evaluated through experimental studies with biomaterial phantom.The reconstructed EIT images with NLMS is better than the images with LMS by amplitude response AR=12.5%,position error PE=200%,resolution RES=33%,and shape deformation SD=66%.Moreover,the Analog-to-Digital Converter(ADC)performances of power spectral density(PSD)and the effective number of bit ENOB with NLMS is higher than the performances with LMS by SI=5.7%and ENOB=15.4%.The results showed that implementing ANC algorithms onto FPGA-based EIT system shows significantly more accurate image reconstruction as compared without ANC algorithms implementation.

关键词： Electrical impedance tomography(EIT) Adaptive Noise Cancellation FPGA-based EIT system time-varying noise model adaptive filter

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一种改进的直接求解声回波消除算法

四川大学学报（自然科学版） 2009年第6期46卷 1714-1718页

作者：陈佐何培宇邵明义 Pei-Yu Ming-Yi 四川大学电子信息学院成都610065

在直接求解声回波消除法的基础上,提出一种改进的直接求解声回波消除算法.该算法将估计的输入信号自相关矩阵做平均处理近似为Toeplitz矩阵,从而可利用Toeplitz线性方程组的快速算法直接求解正则方程,大幅降低了原直接求解法的计算量.... 详细信息

在直接求解声回波消除法的基础上,提出一种改进的直接求解声回波消除算法.该算法将估计的输入信号自相关矩阵做平均处理近似为Toeplitz矩阵,从而可利用Toeplitz线性方程组的快速算法直接求解正则方程,大幅降低了原直接求解法的计算量.同时仿真表明该改进算法仍具有较好的声回波消除效果,尤其是在有强背景噪声时具有稳健的性能.

关键词：改进算法直接求解法回波消除算法 acoustic echo Cancellation solution improved algorithm Toeplitz matrix 声回波 fast algorithm Toeplitz矩阵 conventional performance application 自相关矩阵线性方程组 especially 正则方程输入信号平均处理快速算法

Uplink Performance Evaluation of CDMA Communication System with RAKE Receiver and Multiple Access Interference Cancellation

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International Journal of Communications, Network and System Sciences 2010年第6期3卷 540-547页

作者： Ayodeji J. Bamisaye Michael O. Kolawole Department of Electrical and Electronics Engineering the Federal University of Technology

In CDMA communication systems, all the subscribers share the common channel. The limitation factor on the system’s capacity is not the bandwidth, but multiuser interference and the near far problem. This paper models CDMA system from the perspective of mobile radio channels corrupted by additive white noise generated by multipath and multiple access interferences. The system’s receiver is assisted using different combining diversity techniques. Performance analysis of the system with these detection techniques is presented. The paper demonstrates that combining diversity techniques in the system’s receivers markedly improve the performance of CDMA systems.

关键词： CDMA Multipath Diversity Multiple Access Interference Cancellation Rake Receiver Parallel Interference Cancellation

Factors for Postponement or Cancellation of Operating Programs Set in the Orthopedics-Traumatology Department of Yalgado Ouédraogo University Teaching Hospital in Ouagadougou (Burkina Faso)

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Open Journal of Orthopedics 2022年第12期12卷 451-462页

作者： Mamoudou Sawadogo Alexandre Stanislas Korsaga Sayouba Tinto Anatole Ouedraogo Didier Denne Christian Darga Abdourahmane Ouangre Anne Valérie Kabore Orthopedic-Traumatology Department Yalgado Ouedraogo University Hospital Center Ouagadougou Burkina Faso Orthopedics-Traumatology Department Regional University Teaching Hospital Ouahigouya Burkina Faso

Objective: The purpose of this work was to study the factors of Cancellations or postponement of regulated operating programs of the Orthopedic-Traumatology unit of Yalgado Ouédraogo University Teaching Hospital. Materials and Methods: This was a prospective descriptive study over a period of six months. All interventions postponed or canceled during the study period were included. Patients who died or were lost to follow-up before surgery were not included. Results and Comments: the postponement/ Cancellation rate was 24.5%. Out of 83 operations cancelled, 72.3% of patients were under 50 years old [extreme 15 and 88 years old]. ASA classes I and II were dominant with 57% and 37% of patients canceled, respectively. There were more postponed interventions (67.5%) than definitive Cancellations (32.5%). The causes found were avoidable in 68.7% of cases. The most common was the unavailability of labile blood products (57%), the lack of financial means (36%) and the absence of the patient (28%). The results of our study show that 53% of the causes of Cancellations were related to the organization of the hospital. Conclusion: the Cancellation rate of orthopedic surgeries remains high at Yalgado Ouédraogo University Teaching Hospital. Most of the causes of Cancellations are potentially preventable and the vast majority of them are related to the organization of the hospital. Financial accessibility to care plays an important role in Cancellations.

关键词： Postponement Cancellation Settled Surgery Orthopedics-Traumatology Causes

Cancellation Causes of Elective Surgical Procedures in a Major Pediatric Surgery Department

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Open Journal of Pediatrics 2022年第1期12卷 131-136页

作者： Salsabil Mohamed Sabounji Mbaye Fall Cheikh Seye Mouhamadou Mansour Diene Gabriel Ngom Pediatric Surgery Department Albert Royer Children’s Hospital Dakar Senegal Pediatric Surgery Department Aristide Le Dantec Hospital Dakar Senegal Pediatric Surgery Department Heinrich Lubke Hospital Diourbel Senegal

Introduction: Cancellation of surgical operation is a surgical operation registered in the official schedule the day before or added to the list after and not carried out on the operating day. The purpose of this work was to determine the causes of Cancellation of elective surgical operations in a major pediatric surgery department in Senegal. Patients and methods: It was a prospective and descriptive study of 278 patients scheduled during a period of 13 weeks. The study took place between April 3rd, 2017, and January 31st, 2018. Mean age was 2.9 years with extremes of 3 days and 15 years. The age group of 29 days to 30 months was the most represented (62.2%). Sex ratio was 1.41. Causes of Cancellation were categorized into administrative and organizational causes, patient-related causes and staff-related causes. Results: Cancellation rate was 29.4%. Patient-related causes were most common (51.2%). Upper Respiratory tract infection (URTI) was commonest reason within this category (57.5%). Organizational causes (28.1%) came second and were mainly represented by the unavailability of the operating room (60.8%) related to breakdowns of anesthesia equipment. Finally, staff-related causes (20.7%) were due for most to the unavailability of the anesthesiologist (12 cases/17). Conclusion: Majority of causes that led to Cancellation of elective surgical operations in our Pediatric surgery department are related to intercurrent illnesses affecting the patient, in particular URTI.

关键词： Cancellation Elective Surgery URTI Pediatric Surgery Surgical Procedures