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Автор: Grafiati

Опубліковано: 6 вересня 2023

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1

Mattera, Davide, Mario Tanda, and Maurice Bellanger. "Comparing the performance of OFDM and FBMC multicarrier systems in doubly-dispersive wireless channels." Signal Processing 179 (February 2021): 107818. http://dx.doi.org/10.1016/j.sigpro.2020.107818.

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2

Abushattal, Abdelrahman, Salah Eddine Zegrar, Ayhan Yazgan, and Hüseyin Arslan. "A Comprehensive Experimental Emulation for OTFS Waveform RF-Impairments." Sensors 23, no. 1 (December 21, 2022): 38. http://dx.doi.org/10.3390/s23010038.

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The orthogonal time-frequency space (OTFS) waveform exceeds the challenges that face orthogonal frequency division multiplexing (OFDM) in a high-mobility environment with high time-frequency dispersive channels. Since radio frequency (RF) impairments have a direct impact on waveform behavior, this paper investigates the experimental implementation of RF-impairments that affect OTFS waveform performance and compares them to the OFDM waveform as a benchmark. Firstly, the doubly-dispersive channel effect is analyzed, and then an experimental framework is established for investigating the impact of RF-impairments, including non-linearity, carrier frequency offset (CFO), I/Q imbalances, DC-offset, and phase noise are considered. The experiments were conducted in a real indoor wireless environment using software-defined radio (SDR) at carrier frequencies of 2.4 GHz and 5 GHz based on the Keysight EXG X-Series devices. The comparison of the performances of OFDM and OTFS in the presence of RF-impairments reveals that OTFS significantly outperforms OFDM.

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3

Solyman, Ahmad AA, Hani Attar, Mohammad R. Khosravi, and Baki Koyuncu. "MIMO-OFDM/OCDM low-complexity equalization under a doubly dispersive channel in wireless sensor networks." International Journal of Distributed Sensor Networks 16, no. 6 (June 2020): 155014772091295. http://dx.doi.org/10.1177/1550147720912950.

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In this article, three novel systems for wireless sensor networks based on Alamouti decoding were investigated and then compared, which are Alamouti space–time block coding multiple-input single-output/multiple-input multiple-output multicarrier modulation (MCM) system, extended orthogonal space–time block coding multiple-input single-output MCM system, and multiple-input multiple-output system. Moreover, the proposed work is applied over multiple-input multiple-output systems rather than the conventional single-antenna orthogonal chirp division multiplexing systems, based on the discrete fractional cosine transform orthogonal chirp division multiplexing system to mitigate the effect of frequency-selective and time-varying channels, using low-complexity equalizers, specifically by ignoring the intercarrier interference coming from faraway subcarriers and using the LSMR iteration algorithm to decrease the equalization complexity, mainly with long orthogonal chirp division multiplexing symbols, such as the TV symbols. The block diagrams for the proposed systems are provided to simplify the theoretical analysis by making it easier to follow. Simulation results confirm that the proposed multiple-input multiple-output and multiple-input single-output orthogonal chirp division multiplexing systems outperform the conventional multiple-input multiple-output and multiple-input single-output orthogonal frequency division multiplexing systems. Finally, the results show that orthogonal chirp division multiplexing exhibited a better channel energy behavior than classical orthogonal frequency division multiplexing, thus improving the system performance and allowing the system to decrease the equalization complexity.

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4

Abenov, R. R., E. V. Rogozhnikov, Ya V. Kryukov, D. A. Pokamestov, and P. A. Abenova. "Experimental Study of a Transmission System Based on FBMC/OQAM." Journal of the Russian Universities. Radioelectronics 24, no. 6 (December 29, 2021): 16–26. http://dx.doi.org/10.32603/1993-8985-2021-24-6-16-26.

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Introduction. This paper investigates a transmission system based on FBMC/OQAM multiplexing. This system is characterized by a high spectral efficiency, thereby attracting interest as an alternative transmission method in future wireless mobile communication standards. However, a disadvantage of the system is the high complexity of signal processing. There are numerous publications that study the FBMC/OQAM system from a theoretical perspective. This paper presents an experimental study of a transmission system based on FBMC/OQAM.Aim. Verification of a transmission system based on FBMC/OQAM multiplexing in a wireless channel.Materials and methods. Computer simulation modeling in Matlab and experimental research using Keysight and Rohde & Schwarz certified measuring instruments.Results. A model of synthesis and signal processing was developed, and a frame structure was proposed. The processing included synchronization, since the study was carried out in a wireless double-dispersive channel. Time synchronization was provided by the method of time-domain correlation. A preamble consisting of two symbols was used for CFO compensation. Channel estimation in FBMC/OQAM was conducted by pilot symbols spread over the time-frequency domain, a method with an auxiliary pilot to compensate for intrinsic interference, as well as Zero Forcing and a linear interpolator. As a result, dependences of the bit error rate on the Eb/N0 in various channels were obtained. An error rate of 10−4 was achieved under the Eb/N0 equal to 13.4 dB, 15.3 dB and 20.9 dB in the first, second and third channel, respectively.Conclusion. A FBMC/OQAM-based transmission system with a linear equalizer can operate without a cyclic prefix in a multipath wireless channel, providing comparable noise immunity to OFDM-CP. Long frames should be used to obtain greater spectral efficiency, due to the presence of a transition zone at the beginning and end of the FBMC/OQAM frame.

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5

Ayadi, Raouia, Inès Kammoun, and Mohamed Siala. "Efficient Offline Waveform Design Using Quincunx/Hexagonal Time-Frequency Lattices." Wireless Communications and Mobile Computing 2017 (2017): 1–16. http://dx.doi.org/10.1155/2017/9207108.

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Conventional orthogonal frequency division multiplexing (OFDM) may turn to be inappropriate for future wireless cellular systems services, because of extreme natural and artificial impairments they are expected to generate. Natural impairments result from higher Doppler and delay spreads, while artificial impairments result from multisource transmissions and synchronization relaxation for closed-loop signaling overhead reduction. These severe impairments induce a dramatic loss in orthogonality between subcarriers and OFDM symbols and lead to a strong increase in intercarrier interference (ICI) and intersymbol interference (ISI). To fight against these impairments, we propose here an optimization of the transmit/receive waveforms for filter-bank multicarrier (FBMC) systems, with hexagonal time-frequency (TF) lattices, operating over severe doubly dispersive channels. For this, we exploit the Ping-pong Optimized Pulse Shaping (POPS) paradigm, recently applied to rectangular TF lattices, to design waveforms maximizing the signal-to-interference-plus-noise ratio (SINR) for hexagonal TF lattices. We show that FBMC, with hexagonal lattices, offers a strong improvement in SINR with respect to conventional OFDM and an improvement of around 1 dB with respect to POPS-FBMC, with rectangular lattices. Furthermore, we show that hexagonal POPS-FBMC brings more robustness to frequency synchronization errors and offers a 10 dB reduction in out-of-band (OOB) emissions, with respect to rectangular POPS-FBMC.

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6

Liu, K., T. Kadous, and A. M. Sayeed. "Orthogonal Time–Frequency Signaling Over Doubly Dispersive Channels." IEEE Transactions on Information Theory 50, no. 11 (November 2004): 2583–603. http://dx.doi.org/10.1109/tit.2004.836931.

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7

Bomfin, Roberto, Marwa Chafii, Ahmad Nimr, and Gerhard Fettweis. "A Robust Baseband Transceiver Design for Doubly-Dispersive Channels." IEEE Transactions on Wireless Communications 20, no. 8 (August 2021): 4781–96. http://dx.doi.org/10.1109/twc.2021.3062263.

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8

Kozek, W., and A. F. Molisch. "Nonorthogonal pulseshapes for multicarrier communications in doubly dispersive channels." IEEE Journal on Selected Areas in Communications 16, no. 8 (1998): 1579–89. http://dx.doi.org/10.1109/49.730463.

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9

Xiaoli Ma and G. B. Giannakis. "Maximum-diversity transmissions over doubly selective wireless channels." IEEE Transactions on Information Theory 49, no. 7 (July 2003): 1832–40. http://dx.doi.org/10.1109/tit.2003.813485.

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10

Buzzi, Stefano, Luca Venturino, Alessio Zappone, and Antonio De Maio. "Blind User Detection in Doubly Dispersive DS/CDMA Fading Channels." IEEE Transactions on Signal Processing 58, no. 3 (March 2010): 1446–51. http://dx.doi.org/10.1109/tsp.2009.2033001.

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11

Liu, Ying-nan, Wei Jiang, Shu-bo Ren, and Qing-lin Liang. "Least Square Estimation of Doubly Selective Wireless Fading Channels." Journal of Electronics & Information Technology 30, no. 9 (April 6, 2011): 2185–88. http://dx.doi.org/10.3724/sp.j.1146.2007.00301.

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12

Cano, A., X. Ma, and G. B. Giannakis. "Block-Differential Modulation Over Doubly Selective Wireless Fading Channels." IEEE Transactions on Communications 53, no. 12 (December 2005): 2157–66. http://dx.doi.org/10.1109/tcomm.2005.860038.

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13

Surabhi, G. D., Rose Mary Augustine, and A. Chockalingam. "On the Diversity of Uncoded OTFS Modulation in Doubly-Dispersive Channels." IEEE Transactions on Wireless Communications 18, no. 6 (June 2019): 3049–63. http://dx.doi.org/10.1109/twc.2019.2909205.

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14

Hunziker, T., and D. Dahlhaus. "Bounds on matched filter performance in doubly dispersive Gaussian WSSUS channels." Electronics Letters 37, no. 6 (2001): 383. http://dx.doi.org/10.1049/el:20010270.

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15

Wang, Xiaojie, and Stephan ten Brink. "SINR Analysis of Different OFDM-Inspired Waveforms Over Doubly Dispersive Channels." IEEE Transactions on Vehicular Technology 69, no. 9 (September 2020): 9459–68. http://dx.doi.org/10.1109/tvt.2020.3004570.

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16

Xiaoli Ma, G. B. Giannakis, and S. Ohno. "Optimal training for block transmissions over doubly selective wireless fading channels." IEEE Transactions on Signal Processing 51, no. 5 (May 2003): 1351–66. http://dx.doi.org/10.1109/tsp.2003.810304.

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17

Wang, Kun, Xuejun Sha, Lin Mei, and Xin Qiu. "Performance Analysis of Hybrid Carrier System with MMSE Equalization over Doubly-Dispersive Channels." IEEE Communications Letters 16, no. 7 (July 2012): 1048–51. http://dx.doi.org/10.1109/lcomm.2012.050112.120414.

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18

Benvenuto, Nevio, Federico Boccardi, and Giambattista Carnevale. "Frequency Domain Realization of Space-Time Receivers in Dispersive Wireless Channels." IEEE Transactions on Signal Processing 55, no. 1 (January 2007): 313–26. http://dx.doi.org/10.1109/tsp.2006.882110.

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19

Baas, N. J., and D. P. Taylor. "Matched filter bounds for wireless communication over Rayleigh fading dispersive channels." IEEE Transactions on Communications 49, no. 9 (2001): 1525–28. http://dx.doi.org/10.1109/26.950339.

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20

Thomas, J., and E. Geraniotis. "Soft iterative multisensor multiuser detection in coded dispersive CDMA wireless channels." IEEE Journal on Selected Areas in Communications 19, no. 7 (July 2001): 1334–51. http://dx.doi.org/10.1109/49.932701.

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21

Zhao, Yu, Xihong Chen, Lunsheng Xue, and Qun Zhang. "Design of Robust Pulses to Insufficient Synchronization for OFDM/OQAM Systems in Doubly Dispersive Channels." Mathematical Problems in Engineering 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/826192.

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This paper presents a pulse shaping method robust to insufficient synchronization in orthogonal frequency division multiplexing with offset quadrature amplitude modulation (OFDM/OQAM) systems over doubly dispersive (DD) channels. The proposed pulse is designed as a linear combination of several well localized Hermite functions. The coefficients optimization problem is modeled as a nonconvex constrained fractional programming problem based on the signal-to-interference ratio (SIR) maximization criterion. An efficient iterative algorithm is applied to simplify the problem to a series of quadratically constrained quadratic program (QCQP) problems which can be solved by semidefinite relaxation (SDR) method. Simulation results show that the proposed pulse is superior to traditional pulses with respect to SIR performance over DD channels in the presence of carrier frequency offset (CFO) and timing offset (TO).

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22

Sangirov, Gulomjon, Yong Qing Fu, and Ye Fang. "A MMSE Channel Estimation Method in QC-LDPC Coded OFDM Systems." Advanced Materials Research 989-994 (July 2014): 3759–62. http://dx.doi.org/10.4028/www.scientific.net/amr.989-994.3759.

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An orthogonal frequency division multiplexing (OFDM) is one of the effective techniques used in wireless communications. In OFDM systems, channel impairments due to multipath dispersive wireless channels can cause deep fades in wireless channels. The OFDM receiver also requires an accurate and computationally efficient channel state information when coherent detection is involved. Therefore, it needs a good robust estimation method of the channel in wireless communication for OFDM systems. And one of these channel estimation methods is minimum mean square error (MMSE) channel estimation. MMSE channel estimation one most used method in OFDM systems. In this work we enhanced robustness of MMSE channel estimation by using it in base of quasi-cyclic low density parity check (QC-LDPC) coded OFDM system.

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23

Idrees, Nazar Muhammad, Xianbin Yu, and Andreas Springer. "Optimal tracking of doubly-selective radio channels for OFDM based modern wireless systems." Physical Communication 35 (August 2019): 100739. http://dx.doi.org/10.1016/j.phycom.2019.100739.

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24

Mokhtari, Zahra, Maryam Sabbaghian, and Rui Dinis. "Downlink Sum-Rates of SC-FDP and OFDM Massive MIMO Systems in Doubly Dispersive Channels." IEEE Transactions on Vehicular Technology 69, no. 8 (August 2020): 8065–79. http://dx.doi.org/10.1109/tvt.2019.2959548.

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25

Tabatabaee, S. M. J. Asgari, and H. Zamiri-Jafarian. "Prototype filter design for FBMC systems via evolutionary PSO algorithm in highly doubly dispersive channels." Transactions on Emerging Telecommunications Technologies 28, no. 4 (June 8, 2016): e3048. http://dx.doi.org/10.1002/ett.3048.

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26

Fang-ming Han and Xian-da Zhang. "Wireless multicarrier digital transmission via weyl-heisenberg frames over time-frequency dispersive channels." IEEE Transactions on Communications 57, no. 6 (June 2009): 1721–33. http://dx.doi.org/10.1109/tcomm.2009.06.070406.

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27

Karl Strecker, Sabit Ekin, and John O'Hara. "M-ary quadrature amplitude modulation order optimization for terahertz wireless communications over dispersive channels." ITU Journal on Future and Evolving Technologies 2, no. 7 (September 30, 2021): 21–30. http://dx.doi.org/10.52953/gqxz9838.

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Highly accurate atmospheric models, based on molecular resonance information contained within the HITRAN database, were used to simulate the propagation of high capacity single-carrier quadrature amplitude modulated signals through the atmosphere for various modulation orders. For high-bandwidth signals such as those considered in this work, group velocity dispersion caused by atmospheric gases distorts the modulated waveform, which may produce bit errors. This leads to stricter Signal-To-Noise Ratio requirements for error-free operation, and this effect is more pronounced in high-order modulation schemes. At the same time, high-order modulation schemes are more spectrally efficient, which reduces the bandwidth required to maintain a given data rate, and thus reduces the total group velocity dispersion in the link, resulting in less distortion and better performance. Our work with M-ary quadrature amplitude modulated signals shows that optimal selection of modulation order can minimize these conflicting effects, resulting in decreased error rate, and reducing the performance requirements placed on any equalizers, other dispersion-compensating technologies, or signal processing hardware.

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28

Lottici, Vincenzo, Ruggero Reggiannini, and Michele Carta. "Pilot-Aided Carrier Frequency Estimation for Filter-Bank Multicarrier Wireless Communications on Doubly-Selective Channels." IEEE Transactions on Signal Processing 58, no. 5 (May 2010): 2783–94. http://dx.doi.org/10.1109/tsp.2010.2041872.

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29

Laraway, Stephen Andrew, and Behrouz Farhang-Boroujeny. "Performance Analysis of a Multicarrier Spread Spectrum System in Doubly Dispersive Channels With Emphasis on HF Communications." IEEE Open Journal of the Communications Society 1 (2020): 462–76. http://dx.doi.org/10.1109/ojcoms.2020.2986323.

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30

Zakrzewski, Zbigniew. "Optical Channel Selection Avoiding DIPP in DSB-RFoF Fronthaul Interface." Entropy 23, no. 11 (November 22, 2021): 1554. http://dx.doi.org/10.3390/e23111554.

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The paper presents a method of selecting an optical channel for transporting the double-sideband radio-frequency-over-fiber (DSB-RFoF) radio signal over the optical fronthaul path, avoiding the dispersion-induced power penalty (DIPP) phenomenon. The presented method complements the possibilities of a short-range optical network working in the flexible dense wavelength division multiplexing (DWDM) format, where chromatic dispersion compensation is not applied. As part of the study, calculations were made that indicate the limitations of the proposed method and allow for the development of an algorithm for effective optical channel selection in the presence of the DIPP phenomenon experienced in the optical link working in the intensity modulation–direct detection (IM-DD) technique. Calculations were made for three types of single-mode optical fibers and for selected microwave radio carriers that are used in current systems or will be used in next-generation wireless communication systems. In order to verify the calculations and theoretical considerations, a computer simulation was performed for two types of optical fibers and for two selected radio carriers. In the modulated radio signal, the cyclic-prefix orthogonal frequency division multiplexing (CP-OFDM) format and the 5G numerology were used.

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31

Sharma, Balajee, and Virendra Singh Chaudhary. "Channel Estimation and Equalization Using FIM for MIMO-OFDM on Doubly Selective Faded Noisy Channels." ECTI Transactions on Electrical Engineering, Electronics, and Communications 20, no. 1 (February 18, 2022): 74–82. http://dx.doi.org/10.37936/ecti-eec.2022201.246107.

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Orthogonal frequency division multiplexing (OFDM) plays an important role in wireless communication due to its high transmission rate. Information is conveyed across spatial and temporal dimensions through the space-time shift keying (STSK) technique which is basically used to handle multiplexing diversity and gains. On the other hand, index modulation integrated OFDM not only communicates information through conventional signal constellations as in classical OFDM, but also through indexes of the subcarriers. In index modulation, the subcarriers are transmitted over a particular index and can be implemented effectively. The active indices are selected and further information bits transmitted. In this paper, to handle such limitations, the deep neural network (DNN) has been proposed for end-to-end performance. Under the noisy and faded channel scenario, channel state information must be acquired to recover the transmitted signal correctly. To evaluate the channel distortion level, a deep learning model is trained offline from simulated data and then applied to online data to estimate and recover the channel state as well as the transmitted signal, respectively, in comparison to the traditional least minimum mean square error (LMMSE) channel estimation technique. The analysis results demonstrate superiority over the conventional LMMSE for channel estimation and signal detection in wireless communications with complex channel distortion and interference. The mean square error (MSE) is evaluated for carrying out performance information in each subcarrier block and to reduce the detector error rate.

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32

Lizeaga, Aitor, Pedro M. Rodríguez, Iñaki Val, and Mikel Mendicute. "Evaluation of 5G Modulation Candidates WCP-COQAM, GFDM-OQAM, and FBMC-OQAM in Low-Band Highly Dispersive Wireless Channels." Journal of Computer Networks and Communications 2017 (2017): 1–11. http://dx.doi.org/10.1155/2017/2398701.

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We analyse some of the candidates for modulations for 5G: FBMC-OQAM, GFDM-OQAM, and WCP-COQAM. Unlike most of the related bibliographies, which are oriented to mobile communications, our research is focused on 5G in cognitive radio based industrial wireless communications. According to the ultrareliability and low-latency requirements of industrial communications, we simulate the aforementioned modulations in low-band transmissions (carrier frequencies below 6 GHz and a bandwidth narrower than 100 MHz) through large indoor spaces and severe multipath channels that emulate industrial halls. Moreover, we give detailed information about WCP-COQAM and how the windowing affects the protection against multipath effect and reduces spectral efficiency compared to GFDM-OQAM. We also compare the aforementioned filtered multicarrier techniques and OFDM in terms of robustness against multipath channels, power spectral density, and spectral efficiency. Based on these results, we aim at providing an approximate idea about the suitability of 5G MCM candidates for industrial wireless communications based on CR.

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33

Wang, Kun, Xuejun Sha, and Lin Mei. "On Interference Suppression in Doubly-Dispersive Channels with Hybrid Single-Multi Carrier Modulation and an MMSE Iterative Equalizer." IEEE Wireless Communications Letters 1, no. 5 (October 2012): 504–7. http://dx.doi.org/10.1109/wcl.2012.071612.120359.

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34

Silva, Fábio, Rui Dinis, and Paulo Montezuma. "Estimation of the Feedback Reliability for IB-DFE Receivers." ISRN Communications and Networking 2011 (August 7, 2011): 1–7. http://dx.doi.org/10.5402/2011/980830.

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Анотація:

single-carrier (SC) modulation with frequency-domain equalization (FDE) combined with iterative (turbo) FDE schemes has been shown to be suitable for cyclic-prefix (CP)-assisted block transmission within broadband wireless systems. Its excellent performance in severely time-dispersive channels, makes it a promising candidate for future broadband wireless systems. In this paper we investigated the impact of the correlation factor estimation in the performance of iterative block decision feedback equalization (IB-DFE) receivers. Since the correlation factor represents a key parameter to ensure the good performance of these receivers, reliable estimates of this factor are needed in the feedback loop. We present several methods to estimate the correlation coefficient. We also propose a technique to compensate the inaccuracy of the estimation.

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35

Song, Lijun, Xia Lei, Maozhu Jin, and Zhihan Lv. "Joint Channel Estimation and Signal Detection for the OFDM System Without Cyclic Prefix Over Doubly-Selective Channels." International Journal of Bifurcation and Chaos 25, no. 14 (December 30, 2015): 1540028. http://dx.doi.org/10.1142/s0218127415400283.

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In the high-speed railway wireless communication, a joint channel estimation and signal detection algorithm is proposed for the orthogonal frequency division multiplexing (OFDM) system without cyclic prefix in the doubly-selective fading channels. Our proposed method first combines the basis expansion model (BEM) and the inter symbol interference (ISI) cancellation to overcome the situation that exists with the fast time-varying channel and the normalized maximum multipath channel exceeding the length of the cyclic prefix (CP). At first, the channel estimation and signal detection can be approximated without considering the ISI. Then, the channel parameters and signal detection are updated through ISI cancellation and circular convolution reconstruction from the frequency domain. The simulations show the algorithm can improve the performance of channel estimation and signal detection.

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36

Hamza, Anis Amazigh, Iyad Dayoub, Ihsen Alouani, and Abderrahmane Amrouche. "Enabling User Relaying in MCM-NOMA Under Doubly Selective Channels Using Iterative Interference Cancellation Schemes for Wireless IoT Networks." IEEE Sensors Letters 6, no. 3 (March 2022): 1–4. http://dx.doi.org/10.1109/lsens.2022.3148330.

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37

Tuzlukov, Vyacheslav. "Performance of Generalized Receiver Employed by Broadband Multicarrier DS-CDMA System Using Space-Time Spreading-Assisted Transmit Diversity." WSEAS TRANSACTIONS ON COMMUNICATIONS 20 (September 29, 2021): 152–71. http://dx.doi.org/10.37394/23204.2021.20.21.

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In this paper the multicarrier direct-sequence code-division multiple access (MC DS-CDMA) using space-time spreading assisted transmit diversity is investigated in the context of broadband wireless communi-cations systems constructed based on the generalized approach to signal processing in noise over frequency-se-lective Rayleigh fading channels. We consider the issue of parameter design for the sake of achieving high-ef-ficiency communications in various dispersive environments. In contrast to the conventional MC DS-CDMA wireless communication system employing the time (T)-domain spreading only, in the present paper the broad-band wireless MC DS-CDMA wireless communication schemes employ both the time (T)-domain and frequen-cy (F)-domain spreading, i.e., employ the TF-domain spreading. The bit-error rate (BER) performance of the space-time spreading assisted broadband MC DS-CDMA wireless communications system is investigated for down-link transmissions associated with the single user and multiuser generalized detectors and is compared with that of the single user correlation detector and the multiuser decorrelating detector. Our study demonstra-tes that with appropriately selecting the system parameters, the broadband MC DS-CDMA wireless communi-cation system using the space-time spreading assisted transmit diversity constitutes a promising downlink tran-smission scheme. This scheme is capable to support ubiquitous communications over diverse communication environments without the BER performance degradation

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38

Saengudomlert, Poompat. "On the Benefits of Pre-Equalization for ACO-OFDM and Flip-OFDM Indoor Wireless Optical Transmissions Over Dispersive Channels." Journal of Lightwave Technology 32, no. 1 (January 2014): 70–80. http://dx.doi.org/10.1109/jlt.2013.2286746.

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39

ZHANG, Yang, Qunfei ZHANG, Yingjie WANG, Chengbing HE, and Wentao SHI. "A low-complexity orthogonal time frequency space modulation method for underwater acoustic communication." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 39, no. 5 (October 2021): 954–61. http://dx.doi.org/10.1051/jnwpu/20213950954.

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Compared with the orthogonal frequency division multiplexing (OFDM) modulation, the orthogonal time frequency space(OTFS) modulation has a lower peak-to-average power ratio. It can effectively resist the time selective fading caused by the Doppler effect and has significant performance advantages over doubly dispersive channels. However, the conventional OTFS linear minimum mean square error (LMMSE) method has a high complexity and is not easy to process in real time. In order to solve this problem, we propose a low-complexity equalization algorithm with infinite norm constraints based on the optimal coordinate reduction. The equalization algorithm not only obtains the optimal solution through a certain number of iterations and avoids direct matrix inversion but also equalizes infinite norm constraints to improve the symbol detection performance gains. At the same time, the OTFS delay-Doppler channel matrix we utilize is sparse and the two-norm squares of each column vector equally reduces the complexity of optimal coordinate descent. Finally, the simulation in the underwater acoustic communication scenario we designed verify the effectiveness of the proposed equalization algorithm. The simulation results show that the performance of the proposed equalization algorithm is close to that of the LMMSE method, while its low complexity is ensured.

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40

Kumar Mohapatra, Pradyumna, Saroja Kumar Rout, Sukant Kishoro Bisoy, Sandeep Kautish, Muzaffar Hamzah, Muhammed Basheer Jasser, and Ali Wagdy Mohamed. "Application of Bat Algorithm and Its Modified Form Trained with ANN in Channel Equalization." Symmetry 14, no. 10 (October 6, 2022): 2078. http://dx.doi.org/10.3390/sym14102078.

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The transmission of high-speed data over communication channels is the function of digital communication systems. Due to linear and nonlinear distortions, data transmitted through this process is distorted. In a communication system, the channel is the medium through which signals are transmitted. The useful signal received at the receiver becomes corrupted because it is associated with noise, ISI, CCI, etc. The equalizers function at the front end of the receiver to eliminate these factors, and they are designed to make them work efficiently with proper network topology and parameters. In the case of highly dispersive and nonlinear channels, it is well known that neural network-based equalizers are more effective than linear equalizers, which use finite impulse response filters. An alternative approach to training neural network-based equalizers is to use metaheuristic algorithms. Here, in this work, to develop the symmetry-based efficient channel equalization in wireless communication, this paper proposes a modified form of bat algorithm trained with ANN for channel equalization. It adopts a population-based and local search algorithm to exploit the advantages of bats’ echolocation. The foremost initiative is to boost the flexibility of both the variants of the proposed algorithm and the utilization of proper weight, topology, and the transfer function of ANN in channel equalization. To evaluate the equalizer’s performance, MSE and BER can be calculated by considering popular nonlinear channels and adding nonlinearities. Experimental and statistical analyses show that, in comparison with the bat as well as variants of the bat and state-of-the-art algorithms, the proposed algorithm substantially outperforms them significantly, based on MSE and BER.

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41

Khan, Muhammad Bilal, Mubashir Rehman, Ali Mustafa, Raza Ali Shah, and Xiaodong Yang. "Intelligent Non-Contact Sensing for Connected Health Using Software Defined Radio Technology." Electronics 10, no. 13 (June 28, 2021): 1558. http://dx.doi.org/10.3390/electronics10131558.

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The unpredictable situation from the Coronavirus (COVID-19) globally and the severity of the third wave has resulted in the entire world being quarantined from one another again. Self-quarantine is the only existing solution to stop the spread of the virus when vaccination is under trials. Due to COVID-19, individuals may have difficulties in breathing and may experience cognitive impairment, which results in physical and psychological health issues. Healthcare professionals are doing their best to treat the patients at risk to their health. It is important to develop innovative solutions to provide non-contact and remote assistance to reduce the spread of the virus and to provide better care to patients. In addition, such assistance is important for elderly and those that are already sick in order to provide timely medical assistance and to reduce false alarm/visits to the hospitals. This research aims to provide an innovative solution by remotely monitoring vital signs such as breathing and other connected health during the quarantine. We develop an innovative solution for connected health using software-defined radio (SDR) technology and artificial intelligence (AI). The channel frequency response (CFR) is used to extract the fine-grained wireless channel state information (WCSI) by using the multi-carrier orthogonal frequency division multiplexing (OFDM) technique. The design was validated by simulated channels by analyzing CFR for ideal, additive white gaussian noise (AWGN), fading, and dispersive channels. Finally, various breathing experiments are conducted and the results are illustrated as having classification accuracy of 99.3% for four different breathing patterns using machine learning algorithms. This platform allows medical professionals and caretakers to remotely monitor individuals in a non-contact manner. The developed platform is suitable for both COVID-19 and non-COVID-19 scenarios.

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42

Trane, Gianpiero, Rito Mijarez, and Jesús Arturo Pérez-Díaz. "Automatic Guided Waves Data Transmission System Using an Oil Industry Multiwire Cable." Sensors 20, no. 3 (February 6, 2020): 868. http://dx.doi.org/10.3390/s20030868.

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Alternative wireless data communication systems are a necessity in industries that operate in harsh environments such as the oil and gas industry. Ultrasonic guided wave propagation through solid metallic structures, such as metal barriers, rods, and multiwire cables, have been proposed for data transmission purposes. In this context, multiwire cables have been explored as a communication media for the transmission of encoded ultrasonic guided waves. This work presents the proprietary hardware design and implementation of an automatic data transmission system based on the propagation of ultrasonic guided waves using as communication channels a high-temperature and corrosion-resistant oil industry multiwire cable. A dedicated communication protocol has been implemented at physical and data link layers, which involved pulse position modulation (PPM), digital signal processing (DSP), and an integrity validation byte. The data transmission system was composed of an ultrasonic guided waves PPM encoded data transmitter, a 1K22 MP-35N multiwire cable, a hardware preamplifier, a data acquisition module, a real-time (RT) DSP LabVIEW (National Instruments, Austin, TX) based demodulator, and a human-machine interface (HMI) running on a personal computer. To evaluate the communication system, the transmitter generated 60 kHz PPM energy packets containing three different bytes and their corresponding integrity validation bytes. Experimental tests were conducted in the laboratory using 1 and 10 m length cables. Although a dispersive solid elastic media was used as a communication channel, results showed that digital data transmission rates, up to 470 bps, were effectively validated.

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43

Beinert, Robert, Peter Jung, Gabriele Steidl, and Tom Szollmann. "Super-resolution for doubly-dispersive channel estimation." Sampling Theory, Signal Processing, and Data Analysis 19, no. 2 (October 13, 2021). http://dx.doi.org/10.1007/s43670-021-00016-0.

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AbstractIn this work we consider the problem of identification and reconstruction of doubly-dispersive channel operators which are given by finite linear combinations of time-frequency shifts. Such operators arise as time-varying linear systems for example in radar and wireless communications. In particular, for information transmission in highly non-stationary environments the channel needs to be estimated quickly with identification signals of short duration and for vehicular application simultaneous high-resolution radar is desired as well. We consider the time-continuous setting and prove an exact resampling reformulation of the involved channel operator when applied to a trigonometric polynomial as identifier in terms of sparse linear combinations of real-valued atoms. Motivated by recent works of Heckel et al. we present an exact approach for off-the-grid super-resolution which allows to perform the identification with realizable signals having compact support. Then we show how an alternating descent conditional gradient algorithm can be adapted to solve the reformulated problem. Numerical examples demonstrate the performance of this algorithm, in particular in comparison with a simple adaptive grid refinement strategy and an orthogonal matching pursuit algorithm.

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44

Tomasin, Stefano. "Efficient Bidirectional DFE for Doubly Selective Wireless Channels." EURASIP Journal on Advances in Signal Processing 2006, no. 1 (March 21, 2006). http://dx.doi.org/10.1155/asp/2006/70572.

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45

Hwang, Sung-Jun, and Philip Schniter. "Efficient Sequence Detection of Multicarrier Transmissions over Doubly Dispersive Channels." EURASIP Journal on Advances in Signal Processing 2006, no. 1 (August 13, 2006). http://dx.doi.org/10.1155/asp/2006/93638.

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46

"Block-Differential Modulation Over Doubly Selective Wireless Fading Channels." IEEE Transactions on Communications 53, no. 11 (November 2005): 1973. http://dx.doi.org/10.1109/tcomm.2005.858640.

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47

Bomfin, Roberto, Ahmad Nimr, Marwa Chafii, and Gerhard Fettweis. "A Robust and Low-Complexity Walsh-Hadamard Modulation for Doubly-Dispersive Channels." IEEE Communications Letters, 2020, 1. http://dx.doi.org/10.1109/lcomm.2020.3034429.

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48

Stojanović, Djuro, Igor Djurović, and Branimir R. Vojcic. "Multicarrier Communications Based on the Affine Fourier Transform in Doubly-Dispersive Channels." EURASIP Journal on Wireless Communications and Networking 2010, no. 1 (December 2010). http://dx.doi.org/10.1155/2010/868314.

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49

Pfadler, Andreas, Tom Szollmann, Peter Jung, and Slawomir Stanczak. "Estimation of Doubly-Dispersive Channels in Linearly Precoded Multicarrier Systems Using Smoothness Regularization." IEEE Transactions on Wireless Communications, 2023, 1. http://dx.doi.org/10.1109/twc.2023.3287948.

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50

Wang, Xuehan, Xu Shi, Jintao Wang, and Jian Song. "On the Doppler Squint Effect in OTFS Systems over Doubly-Dispersive Channels: Modeling and Evaluation." IEEE Transactions on Wireless Communications, 2023, 1. http://dx.doi.org/10.1109/twc.2023.3265989.

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