Journal articles: 'Multi-user detector'

1

Xiao, P., and R. Liu. "Multi-user detector for multi-carrier CDMA systems." Electronics Letters 44, no. 23 (2008): 1366. http://dx.doi.org/10.1049/el:20082130.

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Bar-Ness, Y., and J. B. Punt. "Adaptive ?Bootstrap? CDMA multi-user detector." Wireless Personal Communications 3, no. 1-2 (1996): 55–71. http://dx.doi.org/10.1007/bf00333923.

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TAM, WAI MAN, FRANCIS C. M. LAU, and CHI K. TSE. "AN APPROACH TO CALCULATE THE BIT ERROR RATES OF MULTIPLE ACCESS CHAOTIC-SEQUENCE SPREAD-SPECTRUM COMMUNICATION SYSTEMS EMPLOYING MULTI-USER DETECTORS." International Journal of Bifurcation and Chaos 14, no. 01 (January 2004): 183–206. http://dx.doi.org/10.1142/s0218127404009181.

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In a multiple access spread-spectrum communication system, the bit error performance is usually limited by the mutual interference between users. The use of multi-user detection is an effective method to reduce such interference. In this paper, we consider two linear multi-user detectors, namely, decorrelating detector and minimum mean-square-error detector, applied to a multiple access chaotic-sequence spread-spectrum communication system. An approach to calculate the bit error rate (BER) for such systems is presented. The calculated BERs are compared with those obtained using brute-force computer simulations which give the true system performance.

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AZMI, PAEIZ. "MULTIUSER INTERFERENCE SUPPRESSION TECHNIQUES FOR DIRECT-SEQUENCE CDMA COMMUNICATION SYSTEMS." Fluctuation and Noise Letters 08, no. 03n04 (December 2008): L323—L332. http://dx.doi.org/10.1142/s0219477508005094.

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In this paper, several techniques for multi-user interference suppression from power-controlled direct-sequence CDMA systems are proposed and the emphasis is on the one-shot structure. The proposed schemes arise from the optimum detector that takes into account the existence of power-controlled chip-synchronous multi-user interference and white Gaussian noise. Restricting the multi-user interference to the power-controlled chip-synchronous case strongly reduces the complexity of the optimum detector. For more reduction in the complexity, some approximations of the obtained techniques are also considered. It is shown that in asynchronous CDMA systems and in the presence of white Gaussian noise, the proposed detectors outperform the correlator with comparable complexity

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ARAI, YOSHIKAZU, KIYOMI IGARASHI, ATSUSHI FUKASAWA, and YUMI TAKIZAWA. "MULTI-USER DETECTION TO ENHANCE THE CAPACITY OF W-CDMA BASED ON THE CONJUGATE GRADIENT METHOD." Journal of Circuits, Systems and Computers 13, no. 02 (April 2004): 313–23. http://dx.doi.org/10.1142/s0218126604001386.

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Multiple users communicate with individually-assigned codes on a single radio carrier frequency in a DS-CDMA system. Mutual interference among codes limits the capacity of the system. Conventional detectors of receivers are designed for a single-user neglecting the mutual interference. Multi-user detection is expected to enhance the capacity by removing the interference factors. In this paper, a new scheme is proposed corresponding to solving a huge matrix equation under multiple access interference (MAI) environments. This scheme is obtained by the mathematical approach to solve a huge matrix equation. The modeling of multi-user detection is shown, and the algorithm is given based on mathematical approach: the Conjugate Gradient Method (CGM). The characteristics of the proposed scheme are evaluated with comparison to the conventional single-user detector. The proposed scheme has been shown to be three times in capacity against single user detection with reduced complexity comparing conventional technologies based on serial and parallel configurations.

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van der Merwe, Johannes Rossouw, Alexander Rügamer, and Wolfgang Felber. "Blind Spoofing GNSS Constellation Detection Using a Multi-Antenna Snapshot Receiver." Sensors 19, no. 24 (December 10, 2019): 5439. http://dx.doi.org/10.3390/s19245439.

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Spoofing of global navigation satellite system (GNSS) signals threatens positioning systems. A counter-method is to detect the presence of spoofed signals, followed by a warning to the user. In this paper, a multi-antenna snapshot receiver is presented to detect the presence of a spoofing attack. The spatial similarities of the array steering vectors are analyzed, and different metrics are used to establish possible detector functions. These include subset methods, Eigen-decomposition, and clustering algorithms. The results generated within controlled spoofing conditions show that a spoofed constellation of GNSS satellites can be successfully detected. The derived system-level detectors increase performance in comparison to pair-wise methods. A controlled test setup achieved perfect detection; however, in real-world cases, the performance would not be as ideal. Some detection metrics and features for blind spoofing detecting, with an array of antennas, are identified, which opens the field for future advanced multi-detector developments.

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Mitra, Rangeet, and Vimal Bhatia. "Kernel-based parallel multi-user detector for massive-MIMO." Computers & Electrical Engineering 65 (January 2018): 543–53. http://dx.doi.org/10.1016/j.compeleceng.2017.02.005.

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Ranga Rao, Md. "Multi User Detector in CDMA Using Elliptic Curve Cryptography." International Journal of VLSI Design & Communication Systems 3, no. 1 (February 29, 2012): 51–67. http://dx.doi.org/10.5121/vlsic.2012.3105.

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Bani, Kavita, and Vaishali Kulkarni. "Comparison of Single User with Multi User Cooperative Spectrum Sensing for Energy Detector at Low SNR Wall." Journal of Physics: Conference Series 2070, no. 1 (November 1, 2021): 012083. http://dx.doi.org/10.1088/1742-6596/2070/1/012083.

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Abstract With rapidly increasing demand in wireless communication, available licensed spectrum resources should be utilized efficiently and actively. Cognitive radio is a device which learns from surrounding environment and transmit its signal when license spectrum is unutilized. Spectrum sensing is the need for Cognitive radio. In this paper, Energy detector is implemented though MATLAB software for single and multiusers. Region of Convergence (ROC) curve is plotted for both normal ED and Cooperative spectrum sensing ED. Results show while increasing number of samples from 1k to 100k, probability of detection is also achieved 0.9 maximum. Increasing SNR from -20dB, -15dB to -10 dB, probability of detection is improved in ROC curve. Also cooperative spectrum sensing with OR rule gives good probability of detection 0.9 to 1.

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Partibane, B., V. Nagarajan, K. S. Vishvaksenan, and R. Kalidoss. "Performance of Multi-User Transmitter Pre-Processing Assisted Multi-Cell IDMA System for Downlink Transmission." Fluctuation and Noise Letters 14, no. 03 (June 29, 2015): 1550030. http://dx.doi.org/10.1142/s0219477515500303.

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In this paper, we present the performance of multi-user transmitter pre-processing (MUTP) assisted coded-interleave division multiple access (IDMA) system over correlated frequency-selective channels for downlink communication. We realize MUTP using singular value decomposition (SVD) technique, which exploits the channel state information (CSI) of all the active users that is acquired via feedback channels. We consider the MUTP technique to alleviate the effects of co-channel interference (CCI) and multiple access interference (MAI). To be specific, we estimate the CSI using least square error (LSE) algorithm at each of the mobile stations (MSs) and perform vector quantization using Lloyd's algorithm, and feedback the bits that represents the quantized magnitudes and phases to the base station (BS) through the dedicated low rate noisy channel. Finally we recover the quantized bits at the BS to formulate the pre-processing matrix. The performance of MUTP aided IDMA systems are evaluated for five types of delay spread distributions pertaining to long-term evolution (LTE) and Stanford University Interim (SUI) channel models. We also compare the performance of MUTP with minimum mean square error (MMSE) detector for the coded IDMA system. The considered TP scheme alleviates the effects of CCI with less complex signal detection at the MSs when compared to MMSE detector. Further, our simulation results reveal that SVD-based MUTP assisted coded IDMA system outperforms the MMSE detector in terms of achievable bit error rate (BER) with low signal-to-noise ratio (SNR) requirement by mitigating the effects of CCI and MAI.

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Liang, Sheng, Yong Xie, Gao Feng Pan, Jun Xue, and Xin Feng Yu. "Simulation and Analysis of Linear Multiple User Detection Based on Simulink." Applied Mechanics and Materials 263-266 (December 2012): 354–59. http://dx.doi.org/10.4028/www.scientific.net/amm.263-266.354.

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In order to study the feasibility of linear Multiple User Detection (MUD) used in multi-objective spread spectrum TT&C, mathematical models of Decorrelation Algorithm (DEC) and Minimum Mean Square Error Algorithm (MMSE) are built. Simulation framework based on Simulink is given. Two algorithms are compared with traditional single user detector. The results of simulation show the two linear MUDs are better than traditional single user detection.

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Yang, Xuezhi, and Branka Vucetic. "A Frequency Domain Multi-User Detector for TD-CDMA Systems." IEEE Transactions on Communications 59, no. 9 (September 2011): 2424–33. http://dx.doi.org/10.1109/tcomm.2011.062111.090546.

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13

LIU, Ting, Liyi ZHANG, Weiwei BAO, and Kang ZOU. "Multi-user detector based on improved binary artificial bee colony algorithm." Journal of Computer Applications 33, no. 1 (September 23, 2013): 171–74. http://dx.doi.org/10.3724/sp.j.1087.2013.00171.

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14

Dua, A. "Adaptive implementation of polynomial expansion detector for multi-user detection in DS-CDMA systems." Electronics Letters 37, no. 23 (2001): 1384. http://dx.doi.org/10.1049/el:20010960.

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15

Sridhar, Bommidi, and Srinivasulu Tadisetty. "Efficient Recursive Least Square Technique for Spectrum Sensing in Cognitive Radio Networks." International Journal of Business Data Communications and Networking 15, no. 2 (July 2019): 1–14. http://dx.doi.org/10.4018/ijbdcn.2019070101.

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Cognitive radio-based systems rely on spectrum sensing techniques to detect whitespaces to exploit. Cognitive radio (CR) is an attractive approach to face the shortage in the electromagnetic spectrum resources and improve the overall spectrum utilization. However, Energy detectors perform far from optimally by affecting the performance of the underlying system. In this article, two spectrum-sensing techniques are considered for CR networks; one based on energy detection and the other based on multi-taper spectral estimation (MSE). This article proposes a new method to optimize the overall performance in cooperative spectrum sensing in cognitive radio (CR) networks. An efficient recursive least square (ERLS)-based approach is proposed in order to optimize the overall performance to monitor the primary user active or inactive stage with use of secondary user while receiving data. An energy detector (ED) and multi-taper (MTM) spectrum sensing techniques are examined as local spectrum sensing techniques. Finally, a genetic algorithm is compared with the proposed system to show the system effectiveness.

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Alami, Fadoua Thami, Noura Aknin, Najat Erradi, and Ahmed El Moussaoui. "Capacity Enhancement by Using a Multi-User Detector on Uplink Synchronous Mode." International Journal of Information Technology and Computer Science 8, no. 6 (June 8, 2016): 21–27. http://dx.doi.org/10.5815/ijitcs.2016.06.03.

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17

Amiri, Kiarash, Joseph R. Cavallaro, Chris Dick, and Raghu Mysore Rao. "A High Throughput Configurable SDR Detector for Multi-user MIMO Wireless Systems." Journal of Signal Processing Systems 62, no. 2 (April 8, 2009): 233–45. http://dx.doi.org/10.1007/s11265-009-0360-5.

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Boudaa, Ahmed. "Combining SFBC_OFDM Systems with SVD Assisted Multiuser Transmitter and Multi user Detector." IOSR Journal of Electronics and Communication Engineering 6, no. 6 (2013): 24–28. http://dx.doi.org/10.9790/2834-0662428.

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19

Huang, Yung-Fa, Tan-Hsu Tan, Chia-Hsin Cheng, Wei-Chen Lai, and Hsing-Chung Chen. "Performance of a novel evolutionary genetic-based multi-user detector for multi-carrier CDMA communication systems." Soft Computing 21, no. 4 (August 19, 2015): 1031–39. http://dx.doi.org/10.1007/s00500-015-1838-7.

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20

Del Re, E., R. Fantacci, S. Morosi, and A. Pugi. "Advanced blind adaptive multi-user detector for communications in nonstationary multipath fading channel." IEEE Transactions on Vehicular Technology 50, no. 6 (2001): 1497–506. http://dx.doi.org/10.1109/25.966580.

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21

Tomita, Mitsuhiro, Noriyoshi Kuroyanagi, Satoru Ozawa, and Naoki Suehiro. "A multi-user CDMA receiver utilizing decorrelating detector with additional dummy pilot response." International Journal of Communication Systems 16, no. 3 (2003): 249–71. http://dx.doi.org/10.1002/dac.586.

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22

Yakhelef, Mohammed, and L. Saidi. "A LINEAR HYBRID MULTI-USER DETECTOR BASED ON SUCCESSIVE INTERFERENCE CANCELLATION AND DECORRELATOR DETECTOR FOR DS/CDMA SYSTEM." Telecommunications and Radio Engineering 79, no. 1 (2020): 39–45. http://dx.doi.org/10.1615/telecomradeng.v79.i1.40.

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23

Zhang, Xu, Peng, Lu, and Zhang. "Rateless Coded Uplink Transmission Design for Multi-User C-RAN." Sensors 19, no. 13 (July 5, 2019): 2978. http://dx.doi.org/10.3390/s19132978.

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Cloud radio access network (C-RAN) is a promising technology for the Internet of Things (IoT). In C-RAN, the remote radio head (RRH) and baseband unit (BBU) in the conventional base station are separated, and each BBU is backward centralized into a virtual BBU pool. In this paper, we consider the uplink transmission for the two-user C-RAN with two RRHs under a block fading channel. A novel rateless coded transmission scheme is designed. During each transmission round, each user keeps transmitting to the RRHs using Raptor code until the BBU pool feeds back an acknowledgement (ACK). With the proposed scheme, each user does not require the instant channel state information, which greatly reduces the system overhead. We also design the quantizer at the RRHs and the iterative multi-user detector and decoder at the BBU pool, based on the belief propagation (BP) algorithm. For the Raptor code applied at each user, we optimize the corresponding output node degree profile, based on extrinsic information transfer (EXIT) analysis for the decoding process at the BBU pool. The resulted degree profiles are optimal in an average sense under all possible channel states. The simulation results show that the rateless coded transmission scheme with the optimized degree profiles outperforms the benchmark degree profile in both bit error rate and average system throughput. Moreover, the achieved performance is close to the theoretical limit.

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Jia Dongli, and Zheng Guoxin. "Memetic Differential Evolution Assisted Minimum Bit Error Rate Detector for Multi-user MIMO System." International Journal of Digital Content Technology and its Applications 5, no. 2 (February 28, 2011): 224–29. http://dx.doi.org/10.4156/jdcta.vol5.issue2.26.

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Kerouédan, Sylvie, Makram Touzri, Patrick Adde, and Samir Saoudi. "A Turbo Decoder Included in a Multi-User Detector: A Solution to be Retained." International Journal of Communications, Network and System Sciences 03, no. 10 (2010): 826–34. http://dx.doi.org/10.4236/ijcns.2010.310112.

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Hatsui, Takaki, Shun Ono, Togo Kudo, Kazuo Kobayashi, Takashi Kameshima, Kyosuke Ozaki, Yoichi Kirihara, Motohiko Omodani, and Nobukazu Teranishi. "Detector Development Status and Outlook of the SACLA/SPring-8 Site." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C686. http://dx.doi.org/10.1107/s2053273314093139.

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X-ray Free-Electron Laser facility, SACLA has been operational for more than 2 years. During the user runs, multi-port charge coupled device (MPCCD) detectors has been extensively used to deliver novel scientific results. In order to strengthen the facility capability, we are developing new variants of the MPCCD detectors[1]. Because some of the features such as high peak signal detection cannot be implemented by CCD technology, novel monolithic process based on silicon-on-insulator (SOI) sensor technology is under development. By employing the novel process, we are developing SOPHIAS sensor targeting the peak signal of 40000 photons at 7 keV within 100 micrometer square[2]. The SPring-8 site has proposed an upgrade of the storage ring to SPring-8 II. After the upgrades, we will obtain brighter x-rays, for example, 10^13 photons/second within a diameter of 100 nanometer. With this kind of bright X-ray sources, X-ray imaging detector with higher count rate, higher frame rate, and higher quantum efficiency up to 20-30 keV region is required. Detector development plan toward these targets are also discussed.

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Arora, Mehul, Sarthak Naithani, and Anu Shaju Areeckal. "A web-based application for face detection in real-time images and videos." Journal of Physics: Conference Series 2161, no. 1 (January 1, 2022): 012071. http://dx.doi.org/10.1088/1742-6596/2161/1/012071.

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Abstract Face detection is widely used in the consumer industry such as advertising, user interfaces, video streaming apps and in many security applications. Every application has its own demands and constraints, and hence cannot be fulfilled by a single face detection algorithm. In this work, we developed an interactive web-based application for face detection in real-time images and videos. Pretrained face detection algorithms, namely Haar cascade classifier, HOG-based frontal face detector, Multi-task Cascaded Convolutional Neural Network (MTCNN) and Deep Neural Network (DNN), were used in the web-based application. A performance analysis of these face detection algorithms is done for various parameters such as different lighting conditions, face occlusion and frame rate. The web app interface can be used for an easy comparison of different face detection algorithms. This will help the user to decide on the algorithm that suits their purpose and requirements for various applications.

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Sarasti-Zambonino, Sebastián, Tania Barahona, and Santos Roque. "Simulation of a HPGe Detector with GEANT4." Revista Politécnica 50, no. 2 (August 4, 2022): 7–14. http://dx.doi.org/10.33333/rp.vol50n2.01.

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Gamma spectroscopy is an analytic technique that identifies isotopes through gamma rays. Currently, gamma spectroscopy is widely used in several science fields, for instance, the study of the hydrodynamics of soils and other applications. Considering the development of computers, it has been developed Monte-Carlo simulation packages, in order to estimate the response of gamma spectroscopy detectors. This work aims to develop a GEANT4 application to estimate the full energy peak efficiency for a HPGe detector and determine the deviation with experimental data. It was carried out measurements of the next radioactive sources, Am-241, Eu-152, Cs-137, and Co-60. These measurements were made at different distances, they were at 0, 5, 10, 20, and 25 cm from the detector’s cover layer. Meanwhile, the simulation was carried out through user action classes to extract energy deposited in the sensitive detector. It was determined full energy peak efficiency of experimental data, through these results, it was estimated a detection factor that measures the deviation between experimental and simulated data. A reason for the deviation was that the simulation did not include the electronic chain of acquisition. Finally, it was suggested that future works should develop a more accurate simulation for multi-emitters isotopes.

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Zhou, Liqing, Henry Leung, Peng Xu, Guobao Ru, Quansheng Zhao, and Da Xu. "The Kalman Filtering Blind Adaptive Multi-user Detector Based on Tracking Algorithm of Signal Subspace." Information 6, no. 1 (January 20, 2015): 3–13. http://dx.doi.org/10.3390/info6010003.

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Cao, Wen-Fei, Yi-Zheng Zhen, Yu-Lin Zheng, Shuai Zhao, Feihu Xu, Li Li, Zeng-Bing Chen, Nai-Le Liu, and Kai Chen. "Open-Destination Measurement-Device-Independent Quantum Key Distribution Network." Entropy 22, no. 10 (September 26, 2020): 1083. http://dx.doi.org/10.3390/e22101083.

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Quantum key distribution (QKD) networks hold promise for sharing secure randomness over multi-partities. Most existing QKD network schemes and demonstrations are based on trusted relays or limited to point-to-point scenario. Here, we propose a flexible and extensible scheme named as open-destination measurement-device-independent QKD network. The scheme enjoys security against untrusted relays and all detector side-channel attacks. Particularly, any users can accomplish key distribution under assistance of others in the network. As an illustration, we show in detail a four-user network where two users establish secure communication and present realistic simulations by taking into account imperfections of both sources and detectors.

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31

Kumar, N. Sathish, and K. R. Shankar Kumar. "Performance Analysis of a Successive Interference Cancellation for Multi-user Detector with VBLAST MIMO wireless Channel." i-manager's Journal on Future Engineering and Technology 5, no. 3 (April 15, 2010): 49–53. http://dx.doi.org/10.26634/jfet.5.3.1144.

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Wang, Jieling, Hong Yang, Xiaolin Hu, and Xianbin Wang. "An Adaline Neural Network-Based Multi-User Detector Improved by Particle Swarm Optimization in CDMA Systems." Wireless Personal Communications 59, no. 2 (January 19, 2010): 191–203. http://dx.doi.org/10.1007/s11277-009-9912-z.

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Yekhlef, Mohammed, and Lamir Saidi. "A low complexity multi‐user detector based on G‐SIC and PIC for DS/CDMA systems." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 31, no. 6 (November 9, 2012): 1815–34. http://dx.doi.org/10.1108/03321641211267137.

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Kumar, Indrajeet, and Ritesh Kumar Mishra. "An Investigation of Spectral Efficiency in Linear MRC and MMSE Detectors with Perfect and Imperfect CSI for Massive MIMO Systems." Traitement du Signal 38, no. 2 (April 30, 2021): 495–501. http://dx.doi.org/10.18280/ts.380229.

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In this paper, the performance of two linear detectors in multi-user (MU) multiple-input multiple-output (MIMO) systems is investigated. The uplink sum rate and lower bound of channel capacity is derived for both maximum-ratio combination (MRC) and minimum mean square error (MMSE) schemes considering imperfect and perfect channel state information (CSI) conditions. Results show that linear detector performance improves dramatically when the number of base station (BS) users is smaller than that of BS antennas. It is being demonstrated that in the case of imperfect CSI and the number of BS antennas in the conditions of perfect CSI the transmitting power of users can be decreased by the square root of the number of BS antennas. Simulation results show that the MMSE detector outperforms the MRC detector. The results indicated that the system's uplink sum rate is increased by using significantly larger antenna arrays as opposed to just one antenna system. The findings of the Monte-Carlo simulation are very close to the analytical results.

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Nazrul Islam, A. K. M., and S. P. Majumder. "Effect of Pointing Error on BER Performance of a Multi-wavelength OCDMA FSO System with SIK Dual Detector Receiver." Journal of Optical Communications 40, no. 3 (July 26, 2019): 247–53. http://dx.doi.org/10.1515/joc-2017-0047.

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Abstract A novel analytical approach is presented to evaluate the bit error rate (BER) performance of a multi-wavelength optical code division multiple access (MW-OCDMA) free space optical (FSO) system using optical domain encoder and sequence inverse keying (SIK) balanced photodetector direct detection receiver taking the effect of pointing errors into considerations. The analysis is carried out to find the expression for the signal, multi-access interference (MAI) and crosstalk at the output of the SIK receiver in presence of pointing error. The BER performance results are evaluated for different values of standard deviation of pointing error, code length, number of simultaneous user and other system parameters. It is found that, MW-OCDMA system offers improved BER performance over single wavelength OCDMA FSO system. However, the performance of an MW-OCDMA system is degraded due to the effect of pointing error between the laser transmitter and optical receiver and the system suffers significant power penalty at a given BER of 10−9. The penalty is found to be 11.0 dB, 24.0 dB and 30 dB for jitter standard deviation of 1.3, 1.8 and 2.5 respectively when code length is 512 and number of user is 8 for number of wavelength 8. Further, the penalty can be greatly reduced by increasing the code length for a given number of user and number of wavelength.

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Botsinis, Panagiotis, Soon Xin Ng, and Lajos Hanzo. "Quantum Search Algorithms, Quantum Wireless, and a Low-Complexity Maximum Likelihood Iterative Quantum Multi-User Detector Design." IEEE Access 1 (2013): 94–122. http://dx.doi.org/10.1109/access.2013.2259536.

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Hashesh, Amira Osama, Heba A. Tag El-Dien, Ahmad A. Aziz El-Banna, and Adly Tag El-Din. "Spectrum sensing in single channel and multi-channel cognitive radio networks." Indonesian Journal of Electrical Engineering and Computer Science 16, no. 2 (November 1, 2019): 812. http://dx.doi.org/10.11591/ijeecs.v16.i2.pp812-817.

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<p>Sensing the existence or absence of primary user is the major chore of cognitive radio networks. Nevertheless, Spectrum sensing is the core process of cognitive radio and with target to find idle channels.Various detection techniques exist, however, energy detection is considered as the most used detector because of its lower computational cost. In this paper, we proposed a study of throughput for a cognitive radio system. We had two scenarios, in the first scenario; a study of throughput against probability of false alarm was done; where, only one channel is sensed, to maximize the individual channel throughput. In the second scenario, multi-channel is sensed to maximize the overall system capacity. In addition, different number of channels is considered with different sensing times and at different throughput costs.The performance of the network has been investigated in terms of maximum throughput for optimal number of CR channels. </p>

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Sinclair, N. W., S. J. Turneaure, Y. Wang, K. Zimmerman, and Y. M. Gupta. "The fast multi-frame X-ray diffraction detector at the Dynamic Compression Sector." Journal of Synchrotron Radiation 28, no. 4 (June 2, 2021): 1216–28. http://dx.doi.org/10.1107/s1600577521003775.

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A multi-frame, X-ray diffraction (XRD) detector system has been developed for use in time-resolved XRD measurements during single-event experiments at the Dynamic Compression Sector (DCS) at the Advanced Photon Source (APS). The system is capable of collecting four sequential XRD patterns separated by 153 ns, the period of the APS storage ring in the 24-bunch mode. This capability allows an examination of the temporal evolution of material dynamics in single-event experiments, such as plate impact experiments, explosive detonations, and split-Hopkinson pressure bar experiments. This system is available for all user experiments at the DCS. Here, the system description and measured performance parameters (detective quantum efficiency, spatial and temporal resolution, and dynamic range) are presented along with procedures for synchronization and image post-processing.

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Hakimi, Walid, and Ammar Mahmoud. "Performance Evaluation of Space-Time and Harq Diversity in MIMO HSDPA." International Journal of Mobile Computing and Multimedia Communications 4, no. 3 (July 2012): 71–86. http://dx.doi.org/10.4018/jmcmc.2012070105.

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Multi-antenna techniques can be used to achieve improved system performance, including improved system capacity (more users per cell) and improved coverage (possibility for larger cells), as well as improved service provisioning, for example, higher per-user data rates. This study provides an overview of space-time diversity technique using Alamouti codes applied to the 3G evolution. The delays introduced by HARQ retransmission decrease the performance of the HSDPA system. Multi-antenna techniques are specifically applied to HSDPA to avoid HARQ retransmissions. The authors demonstrate that space-time Rake detector in MIMO 2x2 based on Alamouti code without HARQ process could give better performances than MIMO 2x1 taking into account the HARQ context. In the case of MIMO 2x2,they also observed that the limit of retransmissions affects the system performance and efficiency. Using the generalized Alamouti coding technique in MIMO 4x4 with Multipath Parallel Interference Canceller (MPIC) detector, we achieve notable improvement of performance under the same channel and signal to-Noise Ratio (SNR) conditions.

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Pazzi, Bianca Maria, Dario Pistoia, and Giancarla Alberti. "RGB-Detector: A Smart, Low-Cost Device for Reading RGB Indexes of Microfluidic Paper-Based Analytical Devices." Micromachines 13, no. 10 (September 23, 2022): 1585. http://dx.doi.org/10.3390/mi13101585.

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A user-friendly, low-cost detector able to read the RGB indexes of microfluidic paper-based analytical devices (µPADs) was developed. The RGB-detector was built with 3D printing using PLA+ and reused Li-ion batteries. It is Arduino-based, which provides an easy interface between the sensor TCS3200, which reads the quadratic wave of the times corresponding to the RGB numbers, the Arduino itself, whose software translates the times into RGB values, and the touchscreen display, NX3224T028, which shows the results. This detector permits multi-sample analysis since it has a sample holder that can keep up to six µPADs simultaneously and rotate after the display’s request. This work shows how the readings of the RGB indexes by the proposed RGB-detector implement the measurements’ reproducibility. As a proof-of-concept, the RGB-detector application to a green array of µPADs for pH measurement coupled with chemometric analysis allowed us to achieve good results in terms of precision and agreement with the pH values measured by a classical pH-meter.

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Suneela, B., E. V. Krishna Rao, Sarat K. Kotamaraju, and K. CH Sri Kavya. "Multi User-Multiple Input Multiple Output Detector Capacity Enhancement by Resource Allocation in Transmission of Physical Layer Network." Journal of Computational and Theoretical Nanoscience 16, no. 5 (May 1, 2019): 2488–94. http://dx.doi.org/10.1166/jctn.2019.7920.

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Kucur, Oğuz, and Guillermo E. Atkin. "Performance of Haar wavelet based scale-code division multiple access (HW/S-CDMA) using decorrelating multi-user detector." Computers & Electrical Engineering 31, no. 7 (October 2005): 468–84. http://dx.doi.org/10.1016/j.compeleceng.2005.07.004.

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Suchomel, Matthew, Gregory Halder, and Lynn Ribaud. "Synchrotron powder diffraction simplified; management of an APS mail-in program." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C789. http://dx.doi.org/10.1107/s2053273314092109.

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Synchrotrons have revolutionized powder diffraction. They enable rapid collection of data with tremendous angular resolution and exceptional statistics. High resolution powder diffraction beamlines employing multiple single crystal analyzer detectors routinely reveal subtle crystallographic distortions undetectable on other powder instruments, and are an important tool at most modern synchrotrons for structural studies of a diverse range of materials. Beamline 11-BM at the Advanced Photon Source (APS) is a dedicated high resolution (ΔQ/Q ~2×10-4) powder diffraction instrument which uses vertical and horizontal beam focusing capabilities and a counting system consisting of twelve perfect crystal analyzers paired with scintillator detectors. This APS beamline supports both traditional on-site experiments and a highly successfully rapid access mail-in program mode. This mail-in program has greatly simplified access for a growing user community (> 250 in 2013) to world-class synchrotron quality powder data for their research and resulting publications (> 100 11-BM citations in 2013). The presentation will provide an overview of 11-BM's unique mail-in program. It will be presented both from the view of an external remote user, and will also highlight the numerous alignment, calibration, correction and merging software routines needed to efficiently and accurately reduce the numerous multi-bank detector datasets associated with a high throughput user program. An integrated web interface has been developed to serve as a user-friendly relational database interface for tracking of samples and datasets throughout all stages of the measurements; from the initial user request to sample disposal. The database and software tools critical for this high-throughput synchrotron powder diffraction program will be discussed in detail. More information about the 11-BM and its mail-in program can be found on the beamline webpage: http://11bm.xray.aps.anl.gov

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Blanchet, Clement E., Alexey V. Zozulya, Alexey G. Kikhney, Daniel Franke, Peter V. Konarev, Weifeng Shang, Robbert Klaering, et al. "Instrumental setup for high-throughput small- and wide-angle solution scattering at the X33 beamline of EMBL Hamburg." Journal of Applied Crystallography 45, no. 3 (May 4, 2012): 489–95. http://dx.doi.org/10.1107/s0021889812013490.

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A setup is presented for automated high-throughput measurements of small-angle X-ray scattering (SAXS) from macromolecular solutions on the bending-magnet beamline X33 of EMBL at the storage ring DORIS-III (DESY, Hamburg). A new multi-cell compartment allows for rapid switching between in-vacuum and in-air operation, for digital camera assisted control of cell filling and for colour sample illumination. The beamline is equipped with a Pilatus 1 M-W pixel detector for SAXS and a Pilatus 300 k-W for wide-angle scattering (WAXS), and results from the use of the Pilatus detectors for scattering studies are reported. The setup provides a broad resolution range from 100 to 0.36 nm without the necessity of changing the sample-to-detector distance. A new optimized robotic sample changer is installed, permitting rapid and reliable automated sample loading and cell cleaning with a required sample volume of 40 µl. All the devices are fully integrated into the beamline control software system, ensuring fully automated and user-friendly operation (attended, unattended and remote) with a throughput of up to 15 measurements per hour.

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Dudak, J., and J. Zemlicka. "Multi bin energy-sensitive micro-CT using large area photon-counting detectors Timepix." Journal of Instrumentation 17, no. 01 (January 1, 2022): C01028. http://dx.doi.org/10.1088/1748-0221/17/01/c01028.

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Abstract X-ray micro-CT has become a popular and widely used tool for the purposes of scientific research. Although the current state-of-the-art micro-CT is on a high technology level, it still has some known limitations. One of the relevant issues is an inability to clearly identify and quantify specific materials. The mentioned drawback can be solved by the energy-sensitive CT approach. Dual-energy CT, which is already frequently used in human medicine, offers the identification of two different materials; for example, it differentiates an intravenous contrast agent from bone or it can indicate the composition of urinary stones. Resolving a larger number of material components within a single object is beyond the capabilities of dual-energy CT. Such an approach requires a higher number of measurements using different photon energies. A possible solution for multi bin, or so-called spectral CT, is the application of photon-counting detectors. Photon counting technology offers an integrated circuitry capable of resolving the energy of incoming photons in each pixel. Therefore, it is possible to collect data in user-defined energy windows. This contribution evaluates the applicability of the large-area photon-counting detector Timepix for multi bin energy-sensitive micro-CT. It presents an experimental phantom study focused on the simultaneous K-edge-based identification and quantification of multiple contrast agents within a single object. The paper describes the collection of multiple energy bins using the Timepix detector operated in the photon counting mode, explains the data processing, and demonstrates the results obtained from an in-house implemented basis material decomposition algorithm.

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Lee, Ki-Hun, and Bang Chul Jung. "A Novel Expectation-Maximization-Based Blind Receiver for Low-Complexity Uplink STLC-NOMA Systems." Sensors 22, no. 20 (October 21, 2022): 8054. http://dx.doi.org/10.3390/s22208054.

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In this paper, we revisit a two-user space-time line coded uplink non-orthogonal multiple access (STLC-NOMA) system for Internet-of-things (IoT) networks and propose a novel low-complexity STLC-NOMA system. The basic idea is that both IoT devices (stations: STAs) employ amplitude-shift keying (ASK) modulators and align their modulated symbols to in-phase and quadrature axes, respectively, before the STLC encoding. The phase distortion caused by wireless channels becomes compensated at the receiver side with the STLC, and thus each STA’s signals are still aligned on their axes at the access point (AP) in the proposed uplink STLC-NOMA system. Then, the AP can decode the signals transmitted from STAs via a single-user maximum-likelihood (ML) detector with low-complexity, while the conventional uplink STLC-NOMA system exploits a multi-user joint ML detector with relatively high-complexity. We mathematically analyze the exact BER performance of the proposed uplink STLC-NOMA system. Furthermore, we propose a novel expectation-maximization (EM)-based blind energy estimation (BEE) algorithm to jointly estimate both transmit power and effective channel gain of each STA without the help of pilot signals at the AP. Somewhat interestingly, the proposed BEE algorithm works well even in short-packet transmission scenarios. It is worth noting that the proposed uplink STLC-NOMA architecture outperforms the conventional STLC-NOMA technique in terms of bit-error-rate (BER), especially with high-order modulation schemes, even though it requires lower computation complexity than the conventional technique at the receiver.

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Brik, Vladimir, Patrick Meade, Gonzalo Merino, Jan Oertlin, David Schultz, and Heath Skarlupka. "IceCube File Catalog." EPJ Web of Conferences 214 (2019): 04055. http://dx.doi.org/10.1051/epjconf/201921404055.

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IceCube is a cubic kilometer neutrino detector located at the south pole. Metadata for files in IceCube have traditionally been handled on an application by application basis, with no user-facing access. There has been no unified view of data files, and users often query the filesystem to locate files. Recently effort has been put into creating a unified view in a central metadata catalog. Going for a simple solution, we created a userfacing REST API backed by a NoSQL database. All major data producers add their metadata to this central catalog. Schema generation is identified as an important aspect of multi-application metadata services.

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Isca, Agostino, Nader Alagha, Riccardo Andreotti, and Marco Andrenacci. "Recent Advances in Design and Implementation of Satellite Gateways for Massive Uncoordinated Access Networks." Sensors 22, no. 2 (January 12, 2022): 565. http://dx.doi.org/10.3390/s22020565.

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This paper provides an overview of recent results of a design, development and performance evaluation study of satellite gateways to receive and manage the traffic from a large population of uncoordinated user terminals. In particular, direct satellite access scenarios for machine-to-machine communications and the Internet of Things have been targeted. Tests were carried out in a representative laboratory environment emulating realistic system scenarios. Performance results, as presented in this paper indicate that the proposed gateway architecture, based on an efficient access protocol, is capable of managing a very high number of uncoordinated terminals transmitting short messages with a low duty cycle. The applicability of the proposed solution to both geostationary and non-geostationary satellite systems has also been examined. The key concept of the gateway is based on a novel receiver architecture that implements the linear minimum mean square error (MMSE) spread spectrum signal detection and successive interference cancellation techniques. The receiver uses features such as a multi-stage detector together with a robust preamble detection. The end-to-end solution includes also the use of a new waveform with a quasi-constant envelope at the terminal to modulate and transmit data packets to be received and detected by the gateway via a satellite link.

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Lam, Mark H. C., and David A. Jans. "Choosing Between Confocal Microscopes : A Fly-Eye's View." Microscopy Today 8, no. 3 (April 2000): 8–9. http://dx.doi.org/10.1017/s1551929500061022.

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We have recently been shopping for a confocal microscope and have found a simple way to test the capabilities of the various units that have been demonstrated to us. Some of the important aspects that we were looking for in our “ideal” multi-user system were:1)Ease of use.2)The ability to obtain good X-Y, X-Z and hence X-Y-Z resolution, and the accurate display of these images.3)The depth within the sample at which the system can resolve structures (this of course depends mostly on the lenses used), but is still an important criteria as it reflects on the system as a whole.4)“extras” such as a transmission detector and reconstruction/ analysis/image manipulation software.

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Okabe, Satoshi, Michihiro Nagao, Takeshi Karino, Satoshi Watanabe, Tomohiro Adachi, Hirohiko Shimizu, and Mitsuhiro Shibayama. "Upgrade of the 32 m small-angle neutron scattering instrument SANS-U." Journal of Applied Crystallography 38, no. 6 (November 12, 2005): 1035–37. http://dx.doi.org/10.1107/s0021889805029201.

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The small-angle neutron scattering instrument, SANS-U, owned by the Institute for Solid State Physics, The University of Tokyo, has been upgraded. The SANS-U is a 32 m SANS instrument installed in 1991 at the guide hall of the JRR-3M research reactor of the Japan Atomic Energy Research Institute, and has been serving for inter-university cooperative research use since 1993. The major upgrades include (i) replacement of the two-dimensional area detector by a multi-wire type position-sensitive proportional counter, (ii) renewal of the operating system from a VAX and sequencers to an integrated PXI system controlled byLabVIEW-RTsoftware, (iii) a focusing collimation system, and (iv) a variety of accessory equipment. These upgrades provide a wide dynamic range of neutron counting, user-friendly operation and real-time circular averaging of two-dimensional data.

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Journal articles on the topic 'Multi-user detector'

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