Artigos de revistas: "Fading multipath channel"

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Gajanada, I. Gede Arya Gangga, Nyoman Pramaita e I. Gusti Agung Komang Diafari Djuni Hartawan. "Design of Orthogonal Variable Spreading Factor (OVSF) Performance Simulation Program in Multipath Fading Channels". Journal of Electrical, Electronics and Informatics 4, n.º 2 (31 de agosto de 2020): 64. http://dx.doi.org/10.24843/jeei.2020.v04.i02.p05.

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The characteristics of wireless channel are determined by multipath propagation. The transmitted signal will be scattered so that it produces fading. Fading influenced by multipath component will cause delay spread which damages the signal. Thus, spread spectrum technology is used by using a bandwidth that is greater than the original signal. The objective of this study was to determine the effect of the number of multipath components on orthogonal variable spreading factor (OVSF) codes on multipath fading channels viewed from values and Bit Error Rate (BER) graphs versus Energy Bits per Noise (Eb/No). This study would compare the performance of OVSF code communication system on multipath channels by varying multipath components of 4, 8, 12, 16 and the length of OVSF codes used of 16, 8 and 4. The simulation results showed an increase in BER values when the number of multipath components was added. The more the number of multipath components used, the more the number of reflected signals that will interfere with the desired signal in the receiver. The length of the OVSF code influences the performance of the OVSF code on the multipath fading channel, because each code has a different processing gain value that is affected by the length of the code used

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Manhas, Pratima, e M. K. Soni. "Performance of OFDM System under Different Fading Channels and Channel Coding". Bulletin of Electrical Engineering and Informatics 6, n.º 1 (1 de março de 2017): 54–61. http://dx.doi.org/10.11591/eei.v6i1.591.

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Orthogonal frequency division multiplexing (OFDM) is a type of multicarrier modulation (MCM) technique in which larger bandwidth is divided into parallel narrow bands each of which is modulated by different subcarriers. All the subcarriers are orthogonal to each other and hence it reduces the interference among various subcarriers. OFDM technique is an efficient modulation technique used in certain wired and wireless application.In a wireless communication channel, the transmitted signal can travel from transmitter to receiver over multiple reflective paths. This results to multipath fading which causes fluctuations in amplitude, phase and angle of arrival of the received signal. For example, the signal which is transmitted from BTS (base transceiver station) may suffer multiple reflections from the buildings nearby, before reaching the mobile station. Such multipath fading channels are classified into slow fading/fast fading and frequency-selective/flat fading channels. This paper discusses the performance of OFDM system using various fading channels and channel coding. The parameter which is known as Bit error rate (BER) is calculated under different fading channels (AWGN, Rayleigh and Rician) for different digital modulation (BPSK, QPSK and QAM) and Channel coding (linear/Cyclic coding). Matlab Simulink tool is used to calculate the BER parameter.

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Yu, Xiao Lei, Yin Shan Yu, Yu Yu Ji e Dong Hua Wang. "Communication Performance of RFID System and Anti-Interference in the Multipath Rayleigh Fading Channel". Applied Mechanics and Materials 239-240 (dezembro de 2012): 1022–26. http://dx.doi.org/10.4028/www.scientific.net/amm.239-240.1022.

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With the communication environment of RFID system developing from near field communication to long distance communication, Rayleigh fading with Doppler frequency shift emerges from multipath effect between the readers and electronic tags. A systemic study was focused on modeling and analysis of channel transmission for Type A tag signals in the multipath Rayleigh fading channel. Furthermore, the OFDM system was added to the RFID tag signals to improve the sensitivity of SNR in the Rayleigh fading channel. The SNR of tag signal is not sensitive in the multipath Rayleigh fading channel. However, the sensitivity increases after OFDM is added to the RFID system and the anti-interference ability is highly improved.

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Marjanović, Zvezdan, Dejan N. Milić e Goran T. Đorđević. "On Numerical Evaluation of Packet-Error Rate for Binary Phase-Modulated Signals Reception over Generalized-K Fading Channels". Facta Universitatis, Series: Mathematics and Informatics 33, n.º 2 (7 de setembro de 2018): 203. http://dx.doi.org/10.22190/fumi1802203m.

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We present a numerical evaluation of packet error rate (PER) for digital binary phase modulations over wireless communication channels. The analysis is valid for a quasistatic fading communication channel, where multipath fading and shadowing appear simultaneously. The approach is based on numerical evaluation of signal-to-noise ratio threshold that is further used in PER computation. We analyze the threshold and PER dependence on signal power, multipath fading and shadowing severity, as well as packet length.

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Samosir, Pebri Yeni, Nyoman Pramaita, I. Gst A. Komang Diafari Djuni Hartawan e Ni Made Ary Esta Dewi Wirastuti. "Performance Analysis of MIMO STBC System in Flat Fading and Frequency Selective Fading Channels". Journal of Electrical, Electronics and Informatics 3, n.º 1 (18 de junho de 2019): 19. http://dx.doi.org/10.24843/jeei.2019.v03.i01.p04.

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Multiple Input Multiple Output (MIMO) technology is a technique that can be used to overcome multipath fading. The multipath fading is caused by signals coming from several paths that experience different attenuations, delays and phases. In a multipath condition, an impulse that sent by the transmitter, will be received by the recipient not as an impulse but as a pulse with a spread width that called delay spread. Delay spread can cause intersymbol interference (ISI) and bit translation errors from the information received. To determine the effect of delay spread on the MIMO system, then MIMO system performance research was performed on flat fading and frequency selective fading channels using the Space Time Block Code (STBC) coding technique. This research was conducted using MatLab 2018a software. The simulation results show that the MIMO STBC system performance on flat fading channels is better than the MIMO STBC system performance on the frequency selective fading channel. This result is analyzed based on the value of BER vs. Eb/No and eye diagram.

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Wang, Jin Peng, Qi Ming Zhu, Fan Cao, Ping Li e Nian Yu Zou. "A Study on Turbo Codes and Rake Received Mixed Algorithm in Multipath Fading Environment". Applied Mechanics and Materials 321-324 (junho de 2013): 2877–82. http://dx.doi.org/10.4028/www.scientific.net/amm.321-324.2877.

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In this paper, a Turbo codes and Rake received mixed algorithm in multipath fading environment is proposed to solve the problems in signal reception in a fading environment of the mobile communication system. Compared to the traditional multi-path reception methods, the advantage of the algorithm can significantly improve system performance; reduce the system error rate by approximately 2.5dB. Moreover, the performance of the system will be improved a lot if the antenna power is equal. Firstly a mixed algorithm in AWGN channel and multipath fading channel is introduced and derived theoretically and then a computer simulation is carried out and the impact of various parameters on network performance is anglicized. The results show that the algorithm can effectively reduce the effects of multipath fading environment on the transmission power attenuation, lower bit error rate, and improve the effectiveness to resistance to multipath fading significantly.

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Fokin, G. "Modeling multi-beam radio channel". Telecom IT 9, n.º 1 (31 de março de 2021): 59–78. http://dx.doi.org/10.31854/2307-1303-2021-9-1-59-78.

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In this work, a simulation model of a radio channel with fading is implemented for use in research of the multipath channel, as well as for assessing the noise immunity of transmission, recep-tion and processing systems in modern and future mobile communication and radio access networks. Formalization of mathematical models of a radio channel with fading, including the Rayleigh amplitude distribution, uniform phase distribution and a given Doppler spectrum, made it possible to visualize the time-frequency and probabilistic characteristics of a radio channel with fading. The implementation of the procedures for delaying and attenuating copies of signals in a multipath radio channel made it pos-sible to reproduce scenarios of flat and frequency selective fading, which are widely used in practice in assessing the noise immunity of signals with given frequency and time characteristics.

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KRSTIĆ, DRAGANA, SUAD SULJOVIĆ, MIHAJLO STEFANOVIĆ, MUNEER MASADEH BANI YASSEIN e DANIJELA ALEKSIĆ. "New Results and Applications about the Level Crossing Rate of SC Receiver output Signal in the Presence of Gamma Shadowing and k-μ or Rician Multipath Fading". WSEAS TRANSACTIONS ON CIRCUITS AND SYSTEMS 20 (28 de junho de 2021): 118–27. http://dx.doi.org/10.37394/23201.2021.20.15.

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In this paper,the wireless communication system with dual SC receiver operating over shadowed multipath fading channel is considered. The multipath fadingis k-μor Rician.The received signal experiences the short term fading which is resulting in SC receiver envelope variation and Gamma long term fading resulting in SC receiver envelope power variation. The closed form expressions for joint probability density functions of SC receiver output signal envelope and their first derivative of SC receiver output signal envelope are calculated for both, k-μand Rician fading. These expressions are used for evaluation of average level crossing rate of SC receiver output signal envelopes. The numerical expressions are plotted to show the effect of Rician fading severity parameter and Gamma shadowing severity parameter on the average level crossing rate of SC receiver output signal envelope.

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Keshvadi, Hatef, Ali Broumandan e Gérard Lachapelle. "Spatial Characterization of GNSS Multipath Channels". International Journal of Antennas and Propagation 2012 (2012): 1–15. http://dx.doi.org/10.1155/2012/236464.

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There is a growing interest in detecting and processing Global Navigation Satellite System (GNSS) signals in indoors and urban canyons by handheld devices. To overcome the signal attenuation problem in such adverse fading environments, long coherent integration is normally used. Moving the antenna arbitrarily while collecting signals is generally avoided as it temporally decorrelates the signals and limits the coherent integration gain. This decorrelation is a function of the antenna displacement and geometry of reflectors and angle of arrival of the received signal. Hence, to have an optimum receiver processing strategy it is crucial to characterize the multipath fading channel parameters. Herein, Angle of Arrival (AoA) and Angle Spread (AS) along with signal spatial correlation coefficient and fading intensity in GNSS multipath indoor channels are defined and quantified theoretically and practically. A synthetic uniform circular array utilizing a right-hand circular polarized (RHCP) antenna has been used to measure the spatial characteristics of indoor GNSS fading channels. Furthermore, rotating effect of a circular polarized antenna on the synthetic array processing and AoA estimation has been characterized. The performance of the beamforming technique via array gain is also assessed to explore the advantages and limitations of beamforming in fading conditions.

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A. Rida, Jafaar Fahad. "Improvement for performance radio frequency in wireless communication based on impulse signal". Indonesian Journal of Electrical Engineering and Computer Science 18, n.º 2 (1 de maio de 2020): 903. http://dx.doi.org/10.11591/ijeecs.v18.i2.pp903-916.

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This research presents the improved performance of mobile wireless communication channel is based on non-line of sight because the mobile propagation channel is very hard to work with direct path between the transmitter and mobile receiver because of city-based area has objects such as rise building, trees, surround structures, and other objects. The mobile wireless spread radio channels have radio propagation mechanisms as a reflection, diffraction, and scattering effect on radio signal as lessening, and distortion or spread time. The most important thing to make real is that the wireless channel is a multipath radio channel. Multipath copies of the same signal with distinct amplitudes, stages and delay times for all multipaths between the transmitter and the receiver. The multipath fading is defined by its impulse response, which includes the facts about the relative time of the recipient's arrival of various indices of multipath additives. The impulse response expresses great characteristics in the time domain such the large bandwidth frequencies and the amplitude output only the value impulse response δ(t) equal to one when the value of time t=0, otherwise, the value impulse response δ(t) equal to zero in all values of the time. Over a time period reaction, the cellular radio channel could be designed as a linear filter with various impulses.

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Xia, Wenhe, Wenting Guan, Zujun Jiang, Yingfeng Meng e Bo Tang. "Modeling and measurement of microwave propagation multipath channels in drill pipe bore". International Journal of Microwave and Wireless Technologies 11, n.º 3 (28 de setembro de 2018): 220–26. http://dx.doi.org/10.1017/s1759078718001277.

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AbstractIn this paper, the characteristics of microwave propagation channels in drill pipe bore are analyzed by regarding the drill pipe as an irregular lossy cylindrical waveguide. An attenuation law is modeled using multipath propagation theory and an experimental statistical method. It is shown from physical measurement results that 5″ and $5^{1/2 \prime \prime} $ drill pipe bores, widely applied in the field of air drilling, can be used as 2.4 GHz band microwave channels with the caveat that the numerous reflective surfaces in the joint section of the drill pipe produce a great deal of reflected waves. Hence, the drill pipe bore has the characteristics of a dual cluster multipath channel, and multipath fading and delay are the primary factors affecting propagation quality. The study's constructed microwave attenuation model, based on multipath channels, can be regarded as the average attenuation of the unit length in the drill pipe bore, and can be used as the basis for simulation and analysis of the longer drill pipe string. In addition, a large delay between the two clusters leads to a significant increase of the root mean square delay spread. Consequently, multipath fading and delay are the main factors affecting the channel transmission rate.

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Leftah, Hussein A., e Huda N. Alminshid. "Channel capacity and performance evaluation of precoded MIMO-OFDM system with large-size constellation". International Journal of Electrical and Computer Engineering (IJECE) 9, n.º 6 (1 de dezembro de 2019): 5024. http://dx.doi.org/10.11591/ijece.v9i6.pp5024-5030.

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Multiple input-multiple output (MIMO) is a multipath diversity exploring approach which is emerged with orthogonal frequency division multiplexing (OFDM) to produce MIMO-OFDM that is widely used in wireless communications. This paper presents a discrete Hart-ley transform (DHT) precoded MIMO-OFDM system over multipath frequency-selective fading channel with large-size quadrature amplitude modulation (16-QAM, 64-QAM and 256-QAM). A mathematical models for the BER and channel capacity over mutlipath fading channels are also derived in this paper. Average Bit-error-rate (BER) and channel capacity of the presented system is considered and compared with that of the traditional MIMO-OFDM. Simulation results shows that the transmission performance and channel capacity of the proposed schemes is better than that of the traditional MIMO-OFDM without a pre-coder.

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Novaković, Dejan M., e Miroslav L. Dukić. "Multistage multiuser detector for multipath fading channel". European Transactions on Telecommunications 12, n.º 6 (novembro de 2001): 471–78. http://dx.doi.org/10.1002/ett.4460120603.

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Zhang, Y. S., e D. B. Li. "Volterra adaptive prediction of multipath fading channel". Electronics Letters 33, n.º 9 (1997): 754. http://dx.doi.org/10.1049/el:19970529.

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Abid, Zainab Majeed. "Performance of Different Concatenated Coding Schemes for CDMA System". Journal of Engineering 24, n.º 12 (3 de dezembro de 2018): 60–72. http://dx.doi.org/10.31026/j.eng.2018.12.06.

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In this paper different channel coding and interleaving schemes in DS/CDMA system over multipath fading channel were used. Two types of serially concatenated coding were presented. The first one composed of Reed-Solomon as outer code, convolutional code as inner code and the interleaver between the outer and inner codes and the second consist of convolutional code as outer code, interleaved in the middle and differential code as an inner code. Bit error rate performance of different schemes in multipath fading channel was analyzed and compared. Rack receiver was used in DS/CDMA receiver to combine multipath components in order to enhance the signal to noise ratio at the receiver.

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Chen, Liang-wei. "Network Service Method under Cloud Environment of Wireless Sensor Networks in Disaster Situation". International Journal of Online Engineering (iJOE) 12, n.º 11 (24 de novembro de 2016): 16. http://dx.doi.org/10.3991/ijoe.v12i11.6231.

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The sensor networks are characterized by tiny, inexpensive, and advanced communication technology. However, wireless ad-hoc sensor networks (WASNs) have some issues such as the limited amount of energy, multipath fading, and some other issues when they applied in disaster situations. For reducing power consumption, we show mathematical analysis of energy saving, and enhanced error symbol probability. The simulation results prove our analysis. As for the multipath fading, we also show the mathematical analysis of fading channel characteristics and channel model, as well as how to mitigate the multipath fading by modulation and diversity techniques. From the simulation results, we prove the proposed system with amplify-and-forward (AF) relaying can achieve a 2.5 dB performance gain the BER 10-4 whereas the achievable improvement is almost a 4 dB at the BER 10-5 when using maximal ratio combining.

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Wang, Shilian, e Zhili Zhang. "Multicarrier chaotic communications in multipath fading channels without channel estimation". AIP Advances 5, n.º 1 (janeiro de 2015): 017139. http://dx.doi.org/10.1063/1.4906984.

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Shukla, P. K., e L. F. Turner. "Channel-estimation-based adaptive DFE for fading multipath radio channels". IEE Proceedings I Communications, Speech and Vision 138, n.º 6 (1991): 525. http://dx.doi.org/10.1049/ip-i-2.1991.0070.

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Alabi, Oluwaseun Yinka, e Michael Kolawole. "Mitigating the Effects of Intereference in a Multipath Prone Environment for a DVB-T Transmission". International Journal of Informatics and Communication Technology (IJ-ICT) 4, n.º 2 (1 de agosto de 2015): 86. http://dx.doi.org/10.11591/ijict.v4i2.pp86-89.

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This paper develops a novel simulation method that seeks to mitigate the effects of interference in a multipath prone environment for a DVB-T transmission by using the AWGN and the Multipath Rayleigh Fading Channel. The channel parameters were optimized until desired result was obtained. The reception performance of the DVB-T system shows that interference though not totally eliminated, can be minimized while transmitting in a multipath prone environment.

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Cuu, Ho Van, Hoang Hiep Le e Nguyen Thi Thu-Hang. "EFFICIENT ANALYSIS OF MIMO-OFDM SYSTEM IN NAKAGAMI-m FADING CHANNEL". Vietnam Journal of Science and Technology 54, n.º 6 (7 de dezembro de 2016): 698. http://dx.doi.org/10.15625/0866-708x/54/6/8311.

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Bit error rate (BER) and symbol error rate (SER) performance response fading parameter for multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) system over Nakagami-m fading channel would be provided in this study. Some channel simulations and evaluations were for 2×2 MIMO-OFDM system in which data are sent from two transmit antennas to two receive antennas. In this study, authors have used binary phase-shift keying (BPSK) and quadrature phase-shift keying (QPSK) modulation techniques to modulate the data stream. In addition, numerical results have been presented and compared for several different environmental propagations such as Nakagami-m, Rician, Rayleigh multipath fading channels, and non-fading additive white Gaussian noise (AWGN) channel. Based on such obtained presentation and comparison, the paper would discuss further about relation between value of paramater m and quality of system.

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Somasekhar, B., Ch Mohana Krishna e Y. Murty. "Investigations on wavelet and Fourier transform based channel estimation in MIMO-OFDM system". International Journal of Engineering & Technology 7, n.º 2.21 (20 de abril de 2018): 228. http://dx.doi.org/10.14419/ijet.v7i2.21.12178.

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In this paper channel estimation methods for MIMO-OFDM system are investigated based on Fourier Transform and Wavelet Transform. The channel estimation algorithm based on Discrete Fourier Transform (DFT) cause energy leakage in multipath channel with non-sample-spaced time delays. Discrete Cosine Transform (DCT) based channel estimator can mitigate the drawback of Discrete Fourier Transform based channel estimator, when the non-sample spaced path delays are available in multipath fading channels. Wavelet based systems provide better spectral efficiency because of no cyclic prefix requirement, with narrow side lobes and also exhibit improved BER performance. Simulation results reveal that the DWT based transform outperforms the conventional DFT and DCT based channel estimator in terms of bit error rate and mean square error.

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Ahmed, Aliyu, e Adeyemi Abel Ajibesin. "Performance of Modulation Techniques over AWGN and Multipath Fading Channels". Advances in Science and Technology 107 (28 de junho de 2021): 182–93. http://dx.doi.org/10.4028/www.scientific.net/ast.107.182.

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The essence of my paper is to intricately look at data transfer with various modulation techniques over various communication channels. And run simulations to uncover the Bit Error Rate (BER) of various relevant scenarios. I will evaluate the performance of modulation techniques from Binary Phase Shift Keying (BPSK or 2PSK) to 16PSK and other modulation techniques with the consideration of time. Their performance will be evaluated and analyzed by calculating their probability of bit error rate (BER) versus the Energy per bit to spectral noise density (Eb/No) over various wireless channel models such as the Additive White Gaussian Noise (AWGN), Rayleigh channel and Ricean channel. My simulation results will graphically display the effective performance of each communication scenario; it will give us a better understanding of why performances of data communications techniques.

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Zhou, Yu Ying. "Improved Channel Estimation for OFDM Systems by Exploiting Ordered Space". Applied Mechanics and Materials 271-272 (dezembro de 2012): 1317–22. http://dx.doi.org/10.4028/www.scientific.net/amm.271-272.1317.

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In this paper, we propose an improved channel estimation method for orthogonal frequency division multiplexing (OFDM) systems in sparse multipath fading channels. The proposed method transforms the channel estimates into an ordered space and uses the minimum description length (MDL) criterion to estimate the number of paths and the path positions. Simulation results demonstrated that an improved channel estimation performance is obtained due to the reduction of signal space.

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Rummler, W., R. Coutts e M. Liniger. "Multipath fading channel models for microwave digital radio". IEEE Communications Magazine 24, n.º 11 (novembro de 1986): 30–42. http://dx.doi.org/10.1109/mcom.1986.1092972.

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Costa, Lucas, Dayan Guimarães, Rausley de Souza e Roberto Bomfin. "Cooperative Spectrum Sensing with Coded and Uncoded Decision Fusion under Correlated Shadowed Fading Report Channels". Sensors 19, n.º 1 (23 de dezembro de 2018): 51. http://dx.doi.org/10.3390/s19010051.

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This article addresses the impact of forward error correction when applied to the report channel transmissions of a centralized decision fusion cooperative spectrum sensing scheme designed to detect idle orthogonal frequency division multiple access (OFDMA) subchannels. The OFDMA signal is transmitted over slow frequency-selective multipath Rayleigh fading channels and sensed using the maximum eigenvalue detection test statistic. The decisions on the OFDMA subchannel occupancy are transmitted to a fusion center over report channels represented by a shadowed fading model combining a three-dimensional spatially correlated shadowing with a slow and flat multipath Rayleigh fading. Binary Bose-Chaudhuri-Hochquenghem (BCH) and Repetition codes are used to protect these decisions. Results show that shadowing correlation severely deteriorates the overall spectrum sensing performance and that error correction may not be able to protect the report channel transmissions. It can be even worse with respect to the system performance especially at low signal-to-noise regimes. In the situations in which error correction is effective, the Repetition code is capable of outperforming the BCH, meaning that the diversity gain may be more relevant than the coding gain when the spectrum sensing decisions are subjected to correlated shadowing.

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Kumar, Sushil, e D. K. Lobiyal. "Sensing Coverage Prediction for Wireless Sensor Networks in Shadowed and Multipath Environment". Scientific World Journal 2013 (2013): 1–11. http://dx.doi.org/10.1155/2013/565419.

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Sensing coverage problem in wireless sensor networks is a measure of quality of service (QoS). Coverage refers to how well a sensing field is monitored or tracked by the sensors. Aim of the paper is to have a priori estimate for number of sensors to be deployed in a harsh environment to achieve desired coverage. We have proposed a new sensing channel model that considers combined impact of shadowing fading and multipath effects. A mathematical model for calculating coverage probability in the presence of multipath fading combined with shadowing is derived based on received signal strength (RSS). Further, the coverage probability derivations obtained using Rayleigh fading and lognormal shadowing fading are validated by node deployment using Poisson distribution. A comparative study between our proposed sensing channel model and different existing sensing models for the network coverage has also been presented. Our proposed sensing model is more suitable for realistic environment since it determines the optimum number of sensors required for desirable coverage in fading conditions.

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She, Feng, Hsiao Hwa Chen e Hongyang Li. "Joint Angular and Time Diversity of Multi-Antenna CDMA Systems in Wireless Fading Channels". International Journal of Wireless Networks and Broadband Technologies 1, n.º 1 (janeiro de 2011): 1–14. http://dx.doi.org/10.4018/ijwnbt.2011010101.

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In this paper, a multi-antenna based receiver structure for direct sequence code division multiple access (DS/CDMA) system is proposed. The proposed scheme exploits the excellent time resolution of a CDMA RAKE receiver and uses an antenna array beamforming structure to resolve multipath returns in both angular and time domains. A much higher diversity gain than that based only on the time domain diversity can be achieved. This work suggests a new space-time diversity paradigm, namely angular-time diversity, which differs from traditional Alamouti-type space-time coded schemes. The impairments caused by multipath and multiuser interference are analyzed. The performance of the proposed receiver in multipath fading channel is explicitly evaluated. An expression for uncoded system bit error probability is derived. Simulation results show the performance improvement in terms of BER due to the use of multi-antenna in the receiver, and the results illustrate that the multi-antenna based receiver works effectively in resolving multipaths in both angular and time domains to achieve performance improvement due to angular and time diversity gain provided by the multi-antenna system.

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Yang, Yi Huai. "A Novel Prediction Model for WBAN Frequency Nonselective Fading Channel". Applied Mechanics and Materials 513-517 (fevereiro de 2014): 729–33. http://dx.doi.org/10.4028/www.scientific.net/amm.513-517.729.

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The prediction of the frequency non-selective WBAN fading channel behaviors is investigated. An novel WBAN prediction channel model is implemented based on Suzuki fading channel and Rice method and the parameters of the proposed model has been adjusted through MEA, MEDS, Jakes and Monte Carlo multipath simulation method. The performance evaluation for the adaptive WBAN channel model based on simulations is given. The validity of the proposed prediction model is confirmed by comparison of the first order statistics of the measured data.

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Baoguo Yang, K. B. Letaief, R. S. Cheng e Zhigang Cao. "Channel estimation for OFDM transmission in multipath fading channels based on parametric channel modeling". IEEE Transactions on Communications 49, n.º 3 (março de 2001): 467–79. http://dx.doi.org/10.1109/26.911454.

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Ndzi, David L., Nick Savage e Boris Gremont. "Spatial and Temporal Variation of Wideband Indoor Channels". International Journal of Antennas and Propagation 2010 (2010): 1–11. http://dx.doi.org/10.1155/2010/735434.

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Extensive studies of the impact of temporal variations induced by people on the characteristics of indoor wideband channels are reported. Singular Value Decomposition Prony algorithm has been used to compute the impulse response from measured channel transfer functions. The high multipath resolution of the algorithm has allowed a detailed assessment of the shapes of individual multipath clusters and their variation in time and space in indoor channels. Large- and small-scale analyses show that there is a significant dependency of the channel response on room size. The presence of people in the channel has been found to induce both signal enhancements and fading with short-term dynamic variations of up to 30 dB, depending on the number of people and their positions within the room. A joint amplitude and time of arrival model has been used to successfully model measured impulse response clusters.

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Diki Andriasmika, I. Wayan, I. G. A. K. Diafari Djuni H e N. M. A. E. Dewi Wirastuti. "ANALISIS INTERCARRIER INTERFERENCE (ICI) SISTEM OFDM-MIMO STBC PADA KANAL FREQUENCY SELECTIVE FADING". Jurnal SPEKTRUM 6, n.º 1 (10 de maio de 2019): 90. http://dx.doi.org/10.24843/spektrum.2019.v06.i01.p13.

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Wireless telecommunications requires high-speed access. One technique used tooWireless telecommunications requires high-speed access. One technique used toovercome multipath fading is Ortoghonal Frequency Division Multiplexing (OFDM). Theweakness of OFDM occurs on the mobile channel due to time variations in the channel, givingrise to intercarrier interference (ICI). The aim of the study is to determine the effect ofnormalized carrier frequency offset on ICI and the effect of frequency selective fading tapchannel. The simulation results show the system performance in calculating the Eb / N0 5 dBvalue that the greater the normalized carrier frequency offset (?), the worse the signal. Thesimulation results show the OFDM-MIMO system performance in calculating the Eb / N0 5 dBvalue that the greater the tap on the channel the worse the signal.vercome multipath fading is Ortoghonal Frequency Division Multiplexing (OFDM). Theweakness of OFDM occurs on the mobile channel due to time variations in the channel, givingrise to intercarrier interference (ICI). The aim of the study is to determine the effect ofnormalized carrier frequency offset on ICI and the effect of frequency selective fading tapchannel. The simulation results show the system performance in calculating the Eb / N0 5 dBvalue that the greater the normalized carrier frequency offset (?), the worse the signal. Thesimulation results show the OFDM-MIMO system performance in calculating the Eb / N0 5 dBvalue that the greater the tap on the channel the worse the signal.

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32

Jaime-Rodríguez, José Jimmy, Carlos Antonio Gómez-Vega, Carlos A. Gutiérrez, José Martín Luna-Rivera, Daniel Ulises Campos-Delgado e Ramiro Velázquez. "A Non-WSSUS Channel Simulator for V2X Communication Systems". Electronics 9, n.º 8 (24 de julho de 2020): 1190. http://dx.doi.org/10.3390/electronics9081190.

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This paper presents a simulator of non-wide sense stationary uncorrelated scattering (non-WSSUS) multipath fading channels for the performance analysis of vehicle-to-everything (V2X) communication systems. The proposed simulator is constructed with the combination of the Monte Carlo and sum-of-cisoids (SOC) principles, and it is suitable for multicarrier transmission schemes such as those defined for dedicated short-range communications (DSRC) and cellular-based V2X (C-V2X) communications. The channel simulator provides an accurate and flexible solution to reproduce the time and frequency (TF) correlation properties of non-WSSUS vehicular channels under arbitrary isotropic and non-isotropic scattering conditions. Furthermore, the proposed simulator allows velocity variations and non-linear trajectories of the mobile stations (MSs). To demonstrate the practical value of the presented simulator, we evaluate the bit error rate (BER) performance of two channel estimation techniques that are considered for IEEE 802.11p transceivers, namely the least squares (LS) estimator and the spectral temporal averaging (STA) technique. The BER performance of both channel estimators was analyzed by considering three propagating scenarios for road safety applications. Our results show that the non-stationary characteristics of the vehicular multipath fading channel have nearly no effects on the LS estimator’s BER performance. In contrast, the performance of the STA estimator is significantly affected by the channel’s non-stationary characteristics. A variation of the original STA technique that applies only a temporal averaging is introduced in this work to improve the system’s BER in non-WSSUS channels.

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Uddin, Jia, Mohammed Faisal, Md Facihul Azam e A. F. M. Muzahidur Rahman. "Performance Analysis of Multicarrier Code Division Multiple Access over Rayleigh Fading Channel". Advanced Materials Research 457-458 (janeiro de 2012): 985–88. http://dx.doi.org/10.4028/www.scientific.net/amr.457-458.985.

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Recently, multi-carrier transmission schemes have been introduced into Code Division Multiple Access (CDMA) systems to gain advantages for high data rate transmission as well as security. Due to pseudorandom code there is no chance to Inter Symbol Interference (ISI). There are different techniques to mitigate multipath fading. One of the method is to transmit identical narrowband direct-sequence (DS) waveforms in parallel over a number of sub-channels using frequency diversity. Implementation this multi-carrier modulation technique in CDMA system is known as multi-carrier CDMA (MC-CDMA). In Rayleigh fading channel, due to multi-carrier modulation, when one subcarrier goes deep fade another subcarrier may remain safe. Therefore it combats multi-path fading and signal can be received in low bit error rate.

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34

Suyoto, Suyoto, Iskandar Iskandar, Sugihartono Sugihartono e Adit Kurniawan. "Improved Timing Estimation Using Iterative Normalization Technique for OFDM Systems". International Journal of Electrical and Computer Engineering (IJECE) 7, n.º 2 (1 de abril de 2017): 905. http://dx.doi.org/10.11591/ijece.v7i2.pp905-911.

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Conventional timing estimation schemes based on autocorrelation experience performance degradation in the multipath channel environment with high delay spread. To overcome this problem, we proposed an improvement of the timing estimation for the OFDM system based on statistical change of symmetrical correlator. The new method uses iterative normalization technique to the correlator output before the detection based on statistical change of symmetric correlator is applied. Thus, it increases the detection probability and achieves better performance than previously published methods in the multipath environment. Computer simulation shows that our method is very robust in the fading multipath channel

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35

Ahmad, Rafik, Devesh Pratap Singh e Mitali Singh. "Ergodic Capacity of MIMO Channel in Multipath Fading Environment". International Journal of Information Engineering and Electronic Business 5, n.º 3 (1 de setembro de 2013): 41–48. http://dx.doi.org/10.5815/ijieeb.2013.03.05.

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36

Sinha, Hemlata, M. R. Meshram e G. R. Sinha. "Performance of Linear Block Coding for Multipath Fading Channel". International Journal of Information Technology and Computer Science 4, n.º 8 (16 de julho de 2012): 51–56. http://dx.doi.org/10.5815/ijitcs.2012.08.06.

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Brayer, K. "Guest Editorial: Fading and Multipath Channel Communications--A Roadmap". IEEE Journal on Selected Areas in Communications 5, n.º 2 (fevereiro de 1987): 65–67. http://dx.doi.org/10.1109/jsac.1987.1146535.

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38

Cozzo, C., e B. L. Hughes. "Space diversity in presence of discrete multipath fading channel". IEEE Transactions on Communications 51, n.º 10 (outubro de 2003): 1629–32. http://dx.doi.org/10.1109/tcomm.2003.818101.

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Novaković, D. M., e M. L. Dukić. "Multistage multiuser detector for DS-CDMA multipath fading channel". Electronics Letters 34, n.º 11 (1998): 1068. http://dx.doi.org/10.1049/el:19980808.

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40

Hendre, Vaibhav S., M. Murugan e Sneha Kamthe. "Performance Analysis of Transmit Antenna Selection with MRC in MIMO for Image Transmission in Multipath Fading Channels Using Simulink". International Journal of Electrical and Computer Engineering (IJECE) 5, n.º 1 (1 de fevereiro de 2015): 119. http://dx.doi.org/10.11591/ijece.v5i1.pp119-128.

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Multiple antenna configurations can be used to increase the data throughput reducing the effects of multipath fading and interference when channel bandwidth is limited. Orthogonal Space Time Block Codes along with Transmit antenna selection can improve the performance of multiple input multiple output systems. In this paper, we present the Transmit Antenna Selection (TAS) technique based on the Maximal Ratio Combining (MRC) scheme with single antenna selection for image transmission. The performance analysis of the system was carried out under different fading channels i.e. Rayleigh and Rician channel for image input. We design end to end TAS/MRC system in Simulink with advancements in the channel designs and receive diversity techniques along with the feedback models. The Bit Error Rate (BER) analysis was performed for the combinations of number of transmit and receive antennas for TAS/MRC system for various fading environments.

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41

Bandjur, Milos, Dragan Radenkovic, Vladeta Milenkovic, Suad Suljevic e Danijel Djosic. "Second order statistics of SC receiver over k-μ multipath fading channel". Serbian Journal of Electrical Engineering 11, n.º 3 (2014): 391–401. http://dx.doi.org/10.2298/sjee140303028b.

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In this paper wireless communication system with dual branch selection combining (SC) diversity receiver operating over k-? multipath fading environment is considered. Closed form expressions for average level crossing rate of SC receiver output signal envelope and average fade duration of proposed system are evaluated. Numerical results are presented graphically to show the influence of Rican factor k and fading severity ? on average level crossing rate and average fade duration.

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42

Istikmal, Istikmal, Adit Kurniawan e Hendrawan Hendrawan. "Joint Routing and Congestion Control in Multipath Channel based on Signal to Noise Ratio with Cross Layer Scheme". International Journal of Electrical and Computer Engineering (IJECE) 8, n.º 4 (1 de agosto de 2018): 2207. http://dx.doi.org/10.11591/ijece.v8i4.pp2207-2219.

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Routing protocol and congestion control in Transmission Control Protocol (TCP) have important roles in wireless mobile network performance. In wireless communication, the stability of the path and successful data transmission will be influenced by the channel condition. This channel condition constraints come from path loss and the multipath channel fading. With these constraints, the algorithm in the routing protocol and congestion control is confronted with the uncertainty of connection quality and probability of successful packet transmission, respectively. It is important to investigate the reliability and robustness of routing protocol and congestion control algorithms in dealing with such situation. In this paper, we develop a detailed approach and analytical throughput performance with a cross layer scheme (CLS) between routing and congestion control mechanism based on signal to noise ratio (SNR) in Rician and Rayleigh as multipath fading channel. We proposed joint routing and congestion control TCP with a cross layer scheme model based on SNR (RTCP-SNR). We compare the performance of RTCP-SNR with conventional routing-TCP and routing-TCP that used CLS with routing aware (RTCP-RA) model. The analyses and the simulation results showed that RTCP-SNR in a multipath channel outperforms conventional routing-TCP and RTCP-RA.

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43

Chengtao Cao, Lihua Xie, Huanshui Zhang e Shoulie Xie. "A robust channel estimator for DS-CDMA systems under multipath fading channels". IEEE Transactions on Signal Processing 54, n.º 1 (janeiro de 2006): 13–22. http://dx.doi.org/10.1109/tsp.2005.861097.

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Zheng, Zi Wei. "Iterative Channel Estimation for the Chinese Digital Television Terrestrial Broadcasting Systems with the Multiple-Antenna Receivers". Advanced Engineering Forum 6-7 (setembro de 2012): 439–44. http://dx.doi.org/10.4028/www.scientific.net/aef.6-7.439.

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Orthogonal frequency division multiplexing is an effective against multipath fading and high data throughput wireless channel transmission technology. Assistance with the inverse fast Fourier transform and fast Fourier transform operation, orthogonal frequency division multiplexing modulation and demodulation operations of the system convenient and convenient hardware implementation, orthogonal frequency division multiplexing, so in the modern digital television terrestrial broadcasting the system is widely used to support high performance bandwidth-efficient multimedia services. Broadband multi-carrier orthogonal frequency division multiplexing with multi-antenna and multi-antenna receiving system, to increase the diversity gain and improve the capacity of the system in different multipath fading channel. Accurate channel estimation in a simple channel equalization and decoding of broadband multi-carrier orthogonal frequency division multiple-antenna receiver and channel estimation accuracy and multiplexing system is very important, is the key to the performance of the overall broadband multi-carrier orthogonal frequency division multiplexing system in the multi-antenna receiver bit error rate. In this paper, iterative channel estimation to plan for digital terrestrial television broadcasting broadband multi-carrier orthogonal frequency division multiple antenna receiver multiplexing system proposal.

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45

Yang, Chang-Yi, e Bor-Sen Chen. "Robust MC-CDMA Channel Tracking for Fast Time-Varying Multipath Fading Channel". IEEE Transactions on Vehicular Technology 59, n.º 9 (novembro de 2010): 4658–64. http://dx.doi.org/10.1109/tvt.2010.2079962.

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Guo, Yinjing, Jianhua Zhang, Yuanyuan Ju e Xiaohan Guo. "A Theoretical Investigation of Channel Wave Multipath Propagation in a Coal Seam". Mathematical Problems in Engineering 2019 (3 de novembro de 2019): 1–7. http://dx.doi.org/10.1155/2019/4314582.

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This study investigates the mechanism of channel wave multipath propagation to determine features of a channel wave in a coal seam. For this purpose, deduction formulas were used for different time delays and propagation paths and, subsequently, a multipath fading channel wave pattern was built. MATLAB software was used to simulate the model. To this end, the characteristics of the coal seam and the surrounding rock were considered. The simulation results were compared with results obtained from the model contained in COMSOL software to verify the accuracy of the model. According to the results obtained from the simulation, the proposed model shows a good match with the COMSOL model, which is a common simulation comparison standard. In addition, the channel wave energy approximates to exponential decay at a constant distance from the source, and the multipath propagation considerably affects its energy attenuation. Furthermore, the multipath reflections’ travel time derivation is accomplished properly in the coal seam.

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Zhang, Gang, Chuan gang Wang, Guo quan Li e Jin zhao Lin. "Design and Performance Analysis of MISO-ORM-DCSK System over Rayleigh Fading Channels". International Journal of Antennas and Propagation 2016 (2016): 1–8. http://dx.doi.org/10.1155/2016/8459109.

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A novel chaotic communication system, named Orthogonality-based Reference Modulated-Differential Chaos Shift Keying (ORM-DCSK), is proposed to enhance the performance of RM-DCSK. By designing an orthogonal chaotic generator (OCG), the intrasignal interference components in RM-DCSK are eliminated. Also, the signal frame format is expanded so the average bit energy is reduced. As a result, the proposed system has less interference in decision variables. Furthermore, to investigate the bit error rate (BER) performance over Rayleigh fading channels, the MISO-ORM-DCSK is studied. The BER expressions of the new system are derived and analyzed over AWGN channel and multipath Rayleigh fading channel. All simulation results not only show that the proposed system can obtain significant improvement but also verify the analysis in theory.

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Obite, Felix, Jafri Din, Kamaludin Mohammad Yusof e Basliza M. Noor. "Investigation of HAPs Propagation Channel for Wireless Access in a Tropical Region at Ka-Band". International Journal of Electrical and Computer Engineering (IJECE) 7, n.º 3 (1 de junho de 2017): 1204. http://dx.doi.org/10.11591/ijece.v7i3.pp1204-1211.

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In the last few years, High Altitude Platforms (HAPs) have attracted considerable effort due to their ability to exploit the advantages of satellite and terrestrial-based systems. Rain attenuation is the most dominant atmospheric impairment, especially at such frequency band. This paper addresses the modelling of rain attenuation and describes a propagation channel model for HAPs at Ka-band to provide efficient and robust wireless access for tropical regions. The attenuation due to rain is modeled based on three years measured data for Johor Bahru to estimate the actual effect of rain on signals at Ka band. The radio propagation channel is usually characterized as a random multipath channel. Specifically, a statistical derivation of probability distribution function for Rayleigh and Rician fading channels are presented. The model consists of multiple path scattering effects, time dispersion, and Doppler shifts acting on the HAPs communication link. Simulation results represent the fading signal level variations. Results show perfect agreement between simulation and theoretical, thereby conforming to the multipath structures. The information obtained will be useful to system engineers for HAPs link budget analysis in order to obtain the required fade margin for optimal system performance in tropical regions.

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Chen, Jiajing, Xuefeng Yin, Li Tian, Nan Zhang, Yongyu He, Xiang Cheng, Weiming Duan e Silvia Ruiz Boqué. "Measurement-Based LoS/NLoS Channel Modeling for Hot-Spot Urban Scenarios in UMTS Networks". International Journal of Antennas and Propagation 2014 (2014): 1–12. http://dx.doi.org/10.1155/2014/454976.

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A measurement campaign is introduced for modeling radio channels with either line-of-sight (LoS) or non-line-of-sight (NLoS) connection between user equipment (UE) and NodeB (NB) in an operating universal mobile telecommunications system. A space-alternating generalized expectation-maximization (SAGE) algorithm is applied to estimate the delays and the complex attenuations of multipath components from the obtained channel impulse responses. Based on a novel LoS detection method of multipath parameter estimates, channels are classified into LoS and NLoS categories. Deterministic models which are named “channel maps” and fading statistical models have been constructed for LoS and NLoS, respectively. In addition, statistics of new parameters, such as the distance between the NB and the UE in LoS/NLoS scenarios, the life-distance of LoS channel, the LoS existence probability per location and per NB, the power variation at LoS to NLoS transition and vice versa, and the transition duration, are extracted. These models are applicable for designing and performance evaluation of transmission techniques or systems used by distinguishing the LoS and NLoS channels.

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Alzamil, A. A. "Assessment of Uplink Massive MIMO in Scattering Environment". Engineering, Technology & Applied Science Research 10, n.º 5 (26 de outubro de 2020): 6290–93. http://dx.doi.org/10.48084/etasr.3743.

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This paper investigates the performance of massive MIMO systems under the effect of multipath propagation environment. Linear Minimum Mean Squared Error (MMSE) is considered to assess the performance of BPBK/OFDM based uplink massive MIMO transmission. Bit Error Rate (BER) and channel capacity in Non Line Of Site (NLOS) multipath fading environment are presented. The results show a correlation between the number of antennas and the performance of the system.

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