Journal articles: 'Multipath fading'

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KRSTIĆ, DRAGANA, SUAD SULJOVIĆ, MIHAJLO STEFANOVIĆ, MUNEER MASADEH BANI YASSEIN, and 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 (June 28, 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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Zhang, Ping Hua, Xiu Liang Huang, and Zhong Yue He. "Research of Anti-Multipath Interference Capability in Direct Sequence Spread Spectrum Communication System by Simulation." Advanced Materials Research 846-847 (November 2013): 592–95. http://dx.doi.org/10.4028/www.scientific.net/amr.846-847.592.

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The effects of multipath fading with time delay longer or shorter than one chip interval on DSSS system are mathematically and experimentally researched. Simulation results indicate that DSSS system can efficiently overcome multipath fading in multipath Rayleigh Fading channels. And the spreading gain is not the higher the better, it must be chosen reasonably.

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Gajanada, I. Gede Arya Gangga, Nyoman Pramaita, and 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, no. 2 (August 31, 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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Wang, Jin Peng, Qi Ming Zhu, Fan Cao, Ping Li, and Nian Yu Zou. "A Study on Turbo Codes and Rake Received Mixed Algorithm in Multipath Fading Environment." Applied Mechanics and Materials 321-324 (June 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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Njemčević, Pamela, Adriana Lipovac, and Vlatko Lipovac. "Improved Model for Estimation of Spatial Averaging Path Length." Wireless Communications and Mobile Computing 2018 (July 12, 2018): 1–13. http://dx.doi.org/10.1155/2018/4704218.

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In mobile communication systems, the transmitted RF signal is subject to mutually independent deterministic path loss and stochastic multipath and shadow fading. As at each spatial location mostly the composite signal samples are measured, their components are distinguished by averaging out the multipath-caused signal level variations, while preserving just the ones due to shadowing. The prerequisite for this is the appropriateness of the local area averaging path length that enables obtaining the local mean (composed of mean path loss and shadow fading) and the multipath fading as difference between the composite signal sample and the local mean. However, the so far reported analytical approaches to estimation of the averaging path length are based on considering either the multipath or just the shadow fading, with applicability limited to only specific topologies and frequencies. Therefore, in this paper, the most widely used Lee analytical method is generalized and improved by considering multipath and shadowing concurrently, so providing the general closed-form elementary-function based estimation of the optimal averaging path length as a function of common multipath and shadow fading parameters characterizing particular propagation environment. The model enables recommendations for the optimal averaging length for all propagation conditions facing the mobile receiver.

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Yu, Xiao Lei, Yin Shan Yu, Yu Yu Ji, and Dong Hua Wang. "Communication Performance of RFID System and Anti-Interference in the Multipath Rayleigh Fading Channel." Applied Mechanics and Materials 239-240 (December 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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Widi Adnyana, Komang Gede, Nyoman Pramaita, and I. Made Oka Widyantara. "UNJUK KERJA KODE ORTHOGONAL M-SEQUENCE DALAM SISTEM DIRECT SEQUENCE SPREAD SPECTRUM MELALUI KANAL MULTIPATH FA." Jurnal SPEKTRUM 9, no. 4 (December 19, 2022): 1. http://dx.doi.org/10.24843/spektrum.2022.v09.i04.p1.

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Multipath and multi-user interference are the main challenges in wireless communication systems. This has become a driving force for the development of data transmission technology that is focused to overcome these problems, one of which is spread spectrum. Spread spectrum is applied to CDMA technology which has the limitations of MAI, so a spreading code is required with specifications that have a very low cross-correlation value as in the orthogonal m-sequence code. In this study, simulate the orthogonal m-sequence code with a length of 8 chips on a multipath fading channel using the Direct Sequence Spread Spectrum system with aims of assessing the performance of the orthogonal m-sequence code on a multipath fading channel, based on the effect of changes in the number of multipath components. The research method used is a Monte Carlo simulation on simulink with the output data in the form of a graph of the comparison value of BER with Eb/No. The results show that on the flat fading channel with the number of components multipath 1, the BER value of the simulation results is in accordance with the BER theory so that the simulation is valid and can be applied to frequency selective fading channels. In the frequency selective fading channel with the number of multipath components 4,6, and 8, the best performance was shown in the multipath 4 component with the smallest BER value, this was influenced by the ACF and CCF values so that the multipath 4 component had the lowest ISI and interference between users.

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Mohammed, Hasan Fadhil, and Ghanim Abdulkareem Mughir. "Performance evaluation of 4-quadrature amplitude modulation over orthogonal frequency division multiplexing system in different fading channels scenarios." International Journal of Electrical and Computer Engineering (IJECE) 12, no. 5 (October 1, 2022): 5123. http://dx.doi.org/10.11591/ijece.v12i5.pp5123-5135.

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Orthogonal frequency division multiplexing (OFDM) is a multicarrier modulation (MCM) technique that divides the wide bandwidth into parallel narrow bands, each of which is modulated by orthogonal subcarriers. Currently, OFDM is a high-spectral efficiency modulation technique that is used in a variety of wired and wireless applications. The transmitted signal in a wireless communication channel spreads from transmitter to receiver through multiple reflective paths. This triggers multipath fading, which causes variations in the received signal's amplitude and phase. Slow/fast and frequency-selective/frequency-nonselective are the main types of multipath fading channels. Therefore, in this paper, we proposed new models for modeling multipath fading channels, such as the exponential fading channel and the Gamma fading channel. In addition, new bit-error-rate (BER) derivations have been derived. The performance of the OFDM system over proposed channel models has been evaluated using Monte-Carlo simulation and compared to the Rayleigh fading channel model. The obtained results via simulations show that the exponential fading channel at a rate parameter (λ=0.5) outperforms the Rayleigh fading channel by 6 dB for all values of Eb/No, while the Gamma fading channel at (α=2) outperforms the Rayleigh fading channel by 3 dB for all values of Eb/No.

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Adi Wiguna Sanjaya, I. Kadek, Nyoman Pramaita, and I. Made Oka Widyantara. "DESAIN SIMULASI UNJUK KERJA KODE SMALL KASAMI PADA KANAL MULTIPATH FADING." Jurnal SPEKTRUM 8, no. 3 (October 1, 2021): 29. http://dx.doi.org/10.24843/spektrum.2021.v08.i03.p4.

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Telecommunication capable of handling interference, fading and no less importantissues regarding the confidentiality of user information is very much needed in the currenttechnological era, to overcome this spread spectrum technology is quite developed in theadvancement of telecommunication technology. In this study, the small kasami code was usedas the spreading code. The purpose of this study is to determine the performance of the smallkasami code with changes in the number of multipath components using multipath fadingchannels. The modulation technique uses digital modulation, namely binary phase shift keying(BPSK) with a small kasami code with a code length of 15 in the spreading and spreadingprocess. Analyzed based on BER (Bit Error Rate) versus EB/No (Energy Bit per Noise). In thesimulation of flat fading performance using 1 multipath component, flat fading serves as an idealreference where the simulation BER should resemble the theoretical BER as simulationvalidation so that it can be used on selective fading channels. Variation of multipathcomponents in frequency selective fading channel produces different BER because there isinterference of multipath signal to the desired signal. The number of multipath components asmany as 11 have the most interference signals resulting in the worst performance. The value ofcross correlation between users has poor performance, where the correlation value of user 1with 2, 3, and 4 is more than 0, this value shows that many signal levels experience interferencebetween users.

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Samosir, Pebri Yeni, Nyoman Pramaita, I. Gst A. Komang Diafari Djuni Hartawan, and 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, no. 1 (June 18, 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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Wu, Guilu, Fan Li, and Huilin Jiang. "Analysis of Multipath Fading and Doppler Effect with Multiple Reconfigurable Intelligent Surfaces in Mobile Wireless Networks." Wireless Communications and Mobile Computing 2022 (January 17, 2022): 1–15. http://dx.doi.org/10.1155/2022/5751316.

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The multipath fading and Doppler effect are well-known phenomena affecting channel quality in mobile wireless communication systems. Within this context, the emergence of reconfigurable intelligence surfaces (RISs) brings a chance to achieve this goal. RISs as a potential solution are considered to be proposed in sixth generation (6G). The core idea of RISs is to change the channel characteristic from uncontrollable to controllable. This is reflected by some novel functionalities with wave absorption and abnormal reflection. In this paper, the multipath fading and Doppler effect are characterized by establishing a mathematical model from the perspective of reflectors and RISs in different mobile wireless communication processes. In addition, the solutions that improve the multipath fading and Doppler effect stemming from the movement of mobile transmitter are discussed by utilizing multiple RISs. A large number of experimental results demonstrate that the received signal strength abnormal fluctuations due to Doppler effect can be eliminated effectively by real-time control of RISs. Meanwhile, the multipath fading is also mitigated when all reflectors deployed are coated with RISs.

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Marjanović, Zvezdan, Dejan N. Milić, and 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, no. 2 (September 7, 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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XIA, YONGXIANG, CHI K. TSE, FRANCIS C. M. LAU, and GÉZA KOLUMBÁN. "PERFORMANCE OF FREQUENCY-MODULATED DIFFERENTIAL-CHAOS-SHIFT-KEYING COMMUNICATION SYSTEM OVER MULTIPATH FADING CHANNELS WITH DELAY SPREAD." International Journal of Bifurcation and Chaos 15, no. 12 (December 2005): 4027–33. http://dx.doi.org/10.1142/s0218127405014465.

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Multipath performance is an important consideration for chaos-based communication systems. In this letter, the performance of the FM-DCSK communication system over multipath fading channels is evaluated by computer simulations. Both Rayleigh fading and Ricean fading are considered, and the low-pass equivalent model of the FM-DCSK system is used in the simulation. Based on this model, we analyze the bit error performance of the system and the effects of system parameters on the bit-error performance.

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M. Abd Elaziz, Nadir. "Radar Echo Signal Multipath Fading." IOSR Journal of Engineering 04, no. 12 (December 2014): 61–066. http://dx.doi.org/10.9790/3021-0412261066.

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Ng, Benjamin K., and Chan-Tong Lam. "Single-Carrier Rotation-Interleaved Space-Time Code for Frequency-Selective Fading Channels." Applied Sciences 12, no. 24 (December 13, 2022): 12803. http://dx.doi.org/10.3390/app122412803.

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A novel single-carrier-based space-time code construction scheme to exploit the advantages of a frequency-selective fading channel is investigated in this paper. The proposed construction scheme is based on multiplexing independent streams of phase-rotated space-time codes in a time-interleaved fashion. The advantage of such design is that it guarantees full space-time-multipath diversity by using traditional space-time codes or MIMO signaling schemes originally designed for flat fading channels as the constituent codes. Another advantage is that this approach incurs no loss in bandwidth efficiency and it alleviates the problem of high PAPR in OFDM-based space-time codes. By employing random or algebraic rotations, the design is potentially suitable for any number of transmit antennas or multipaths. The simulation results indicate that full space-time-multipath diversity is attained using this new approach, and comparisons with some existing space-time codes designed for frequency-selective channels are made to show its performance advantage.

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Keshvadi, Hatef, Ali Broumandan, and 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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Chen, Liang-wei. "Network Service Method under Cloud Environment of Wireless Sensor Networks in Disaster Situation." International Journal of Online Engineering (iJOE) 12, no. 11 (November 24, 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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Widi Arjana Yasa, I. Ketut, Nyoman Pramaita, and Ni Made Ary Esta Dewi Wirastuti. "DESAIN PROGRAM SIMULASI UNJUK KERJA KODE LARGE KASAMI PADA SISTEM KOMUNIKASI DIRECT SQUENCE SPREAD SPECTRUM MELALUI KANAL MULTIPATH FADING." Jurnal SPEKTRUM 8, no. 3 (October 31, 2021): 51. http://dx.doi.org/10.24843/spektrum.2021.v08.i03.p7.

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Selection of Pseudo Noise (PN) code in CDMA multiple access is needed to overcomeproblems related to interference. In this study, we simulate the large kasami code with the aimof knowing the performance of the large kasami code on flat fading channels and frequencyselective fading channels with variations in the number of multipath components. The receiversystem uses a correlation receiver to correlate the code used by each user. The simulationresults from the performance of the large kasami code through the flat fading channel show thatthe simulation carried out is valid, where the simulation BER value is close to the flat theoreticalBER value. The frequency selective fading channel shows different BER values from variationsin the number of multipath components, where the multipath 60 component produces the worstBER value. Auto correlation code large kasami has a value when the time is not equal to zerowhich can interfere with the desired signal and there is a cross-correlation signal level value thatwill interfere with each other's users.

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She, Feng, Hsiao Hwa Chen, and 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, no. 1 (January 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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Allanki Sanyasi Rao and Kallepelli Srikanth, Karthik Kumar Vaigandla,. "Study of Modulation Schemes over a Multipath Fading Channels." International Journal for Modern Trends in Science and Technology 7, no. 10 (October 31, 2021): 34–39. http://dx.doi.org/10.46501/ijmtst0710005.

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Communications systems concerted over wireless channels depend on the environment. Communications system can be more reliable and efficient by properly analyzing wireless channels. Today's most important features are a high data rate and reliable performance to exploiting viable networks during this new information age. The channel is not time-invariant in wireless communication, so the received signal exhibits amplitude, phase, and angle variations due to multipath fading. Increasing data rates and reducing bandwidth make Orthogonal Frequency Division Multiplexing (OFDM) an important component of wireless communication systems. The OFDM technique uses many carriers very efficiently. With this scheme, interference is robustly reduced, and fading scenarios are easily accommodated. Analyzing digital modulation schemes requires evaluating link performance with fading channels. The paper compares channel performance over varying fading environments using a variety of modulation schemes. We study the BER and SNR properties of the AWGN, Rician fading and Rayleigh fading channels modulated with BPSK, QPSK, and M-ary QAM.

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Medard, M., and R. G. Gallager. "Bandwidth scaling for fading multipath channels." IEEE Transactions on Information Theory 48, no. 4 (April 2002): 840–52. http://dx.doi.org/10.1109/18.992769.

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Yousef, Nabil R., Ali H. Sayed, and Nima Khajehnouri. "Detection of fading overlapping multipath components." Signal Processing 86, no. 9 (September 2006): 2407–25. http://dx.doi.org/10.1016/j.sigpro.2005.11.002.

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Chang Heon Lim and Jae Kwon Jeong. "Adaptive modulation using multipath fading compensation." Electronics Letters 34, no. 10 (1998): 940. http://dx.doi.org/10.1049/el:19980653.

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Abid, Zainab Majeed. "Performance of Different Concatenated Coding Schemes for CDMA System." Journal of Engineering 24, no. 12 (December 3, 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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BAI, ZHIQUAN, YUANQUAN XU, XIAOTONG LI, RONGKAI LI, DONGFENG YUAN, and KYUNGSUP KWAK. "MIMO DS-BPAM UWB SYSTEM WITH SRAKE RECEIVER OVER MULTIPATH FADING CHANNELS." Journal of Circuits, Systems and Computers 18, no. 06 (October 2009): 1075–80. http://dx.doi.org/10.1142/s021812660900554x.

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In this paper, we investigate the multiple input multiple output (MIMO) direct sequence bipolar pulse amplitude modulation (DS-BPAM) ultra wideband (UWB) system over indoor multipath fading channels based on the research of Alamouti space-time block codes (STBC) and DS-BPAM UWB system. Selective Rake (SRake) receiver is employed in this paper in order to deal with the multipath effects. Theoretical bit error probability of the MIMO DS-BPAM UWB system with SRake receiver is derived. Simulation results of the MIMO DS-BPAM UWB system with SRake receiver and conventional coherent receiver over multipath fading channels are provided. The results show the efficiency of the MIMO DS-BPAM UWB system with SRake receiver.

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Kumar, Sushil, and 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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Mudhoep, Debbi Irfan, Rukmi Sari Hartati, and Yoga Divayana. "Peningkatan Unjuk Kerja Pada Link Microwave Menggunakan Teknik Diversity Maximal Ratio Combining." Majalah Ilmiah Teknologi Elektro 19, no. 2 (December 31, 2020): 127. http://dx.doi.org/10.24843/mite.2020.v19i02.p01.

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Pada system komunikasi menggunakan gelombang microwave ( link microwave ), adanya noise serta multipath fading dapat mengurangi dan menurunkan kinerja system komunikasi. Perambatan gelombang mikro dipengaruhi beberapa hal pada system penerimaan selain harus LOS ( Line Of Sight ) terdapat sinyal pantulan dari permukaan yang sangat menimbulkan interferensi ( sinyal multipath ). Dengan menggunakan teknik diversity maximal ratio combining pada system yang terkena noise dan fading digunakan melalui analisa BER ( Bit Error Rate ). Penggunaan simulasi penelitian untuk mengetahui perbaikan system di penerima dengan membandingkan sebelum dan sesudah penggunaan teknik maximal ratio combining

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Fokin, G. "Modeling multi-beam radio channel." Telecom IT 9, no. 1 (March 31, 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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F. Mohammed, Hassan, and Ghanim A. Al-Rubaye. "BER PERFORMANCE ANALYSIS OF 4QAM/OFDM OVER DIFFERENT SCENARIOS OF LAPLACE FADING CHANNEL." Journal of Engineering and Sustainable Development 25, Special (September 20, 2021): 1–26. http://dx.doi.org/10.31272/jeasd.conf.2.1.4.

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Multicarrier transmission, also known as (OFDM) Orthogonal Frequency Division multiplexing, in wireless communications, it has been proven to be an essential technique for countering multipath fading. It has been used successfully for HF radio applications and has been selected as the interface for digital audio transmission, digital terrestrial TV broadcasting, and high-speed wireless local area networks in Europe. In this paper, we suggested a new design for modeling multipath fading channels, such as the Laplace fading channel, in order to discover new simulation results and effects. Furthermore, the variance of the Laplace fading channel has been computed and the new Bit Error Rate (BER) derivation is established, and the performance of (M-QAM), M-ary Quadrature Amplitude Modulation (with M=4 over OFDM system under Laplace fading channels in Additive White Gaussian Noise (AWGN) is discussed and compared to the conventional M-QAM/OFDM system Rayleigh fading channel in AWGN. All the simulation results are examined using the optimum signal detection based on the Euclidean distance and evaluated using Monte-Carlo simulation.

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Kurnia, Mohammad Andri, Eka Wahyudi, and Solichah Larasati. "Comparison of Hybrid Diversity and Space Diversity for Microwave Link Between Islands." CESS (Journal of Computer Engineering, System and Science) 5, no. 2 (July 6, 2020): 285. http://dx.doi.org/10.24114/cess.v5i2.18160.

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The development of telecommunications technology today, so that some islands are still not affordable from telecommunications technology. The considerable distance between islands requires the efficiency and flexibility of the technology used. The microwave communication system is a technology that is widely implemented as a cellular network backhaul network because it has advantages in the simplicity of installation and can reach remote areas that are difficult to reach. But on the receiving side, the signal received not only comes from the LOS (Line of Sight) signal but the signal is also reflected by the surface of the Earth. The signal from some of these reflections is called multipath, the signal will cause interference that can cause fading or changes in the electromagnetic waves received. To overcome multipath fading that is too high, it is necessary to optimize antenna diversity using hybrid diversity and space diversity techniques. At maximum optimization of hybrid diversity with 135λ and 300 MHz, RSL -34.54 dBm is obtained, the fading margin is 33.70 dB, and availability is 99.99987%, the optimization is better than space diversity at maximum optimization with 135λ. Optimization of hybrid diversity has met ITU-R standards, with RSL values below -30 dBm and availability above 99.900% - 99.9966%, for the value of fading margins still do not meet the standards but can overcome multipath fading problems.

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Sadrieh, Seyed Nima, Ali Broumandan, and Gérard Lachapelle. "Doppler Characterization of a Mobile GNSS Receiver in Multipath Fading Channels." Journal of Navigation 65, no. 3 (April 4, 2012): 477–94. http://dx.doi.org/10.1017/s037346331200015x.

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Global Navigation Satellite Systems (GNSS) Doppler measurements are commonly used for velocity-based relative positioning and aiding Inertial Navigation Systems (INS) in signal degraded environments. The aim of this paper is to characterise the Doppler measurements in GNSS harsh multipath environments. In multipath fading situations such as indoor and urban canyon environments, multipath components arrive to the receiver antenna from different paths and directions. These give rise to various Doppler shifts that cause errors in the velocity solution. In this work the Doppler measurements discrepancy characterised by Doppler spread in multipath environments is investigated. By assuming a ‘sphere of scatterers’ model and considering the antenna gain pattern, the theoretical Power Spectral Density (PSD) observed by a receiver is formulated. The theoretical findings are examined using two sets of measurements in dense multipath environments. Global Positioning System (GPS) live signals using non-isotropic antennas with different orientations are used for this purpose. Different motion directions are also examined using different data sets. An Assisted GPS (A-GPS) approach is utilised where the code phase and the navigation data bits are provided by a nearby outdoor antenna. By applying a ‘Block Processing’ technique, an epoch-by-epoch Doppler and velocity estimation is implemented. Herein, the Doppler and velocity measurements accuracy in addition to the Doppler spread characterization are studied. As shown both theoretically and experimentally, in harsh multipath environments the PSD of the observed signals is a function of the scatterers' geometry and the antenna gain pattern. The Doppler estimation accuracies in multipath and multipath-free cases are compared for different ranges of Carrier-to-Noise ratio (C/N0). Theoretical and experimental results revealed inaccurate Doppler estimation and poor Doppler-derived velocity solutions in dense multipath environments.

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Manhas, Pratima, and M. K. Soni. "Performance of OFDM System under Different Fading Channels and Channel Coding." Bulletin of Electrical Engineering and Informatics 6, no. 1 (March 1, 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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Wu, Ya Ting, Yan Zan Sun, and Xi Luo. "Delay-Locked Loop for Pseudorange Measurement over Frequency-Selective Fading Channels." Applied Mechanics and Materials 303-306 (February 2013): 2050–53. http://dx.doi.org/10.4028/www.scientific.net/amm.303-306.2050.

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A delay-locked loop is proposed for accurate code tracking over frequency-selective fading channels in this paper. Taking advantage of the shift-and-add property of maximum length pseudorandom spread-spectrum sequences, the differential multiplier is employed to separate each multipath component and reduce the effects of other multipath signals. The contribution of all the multipath signals is combined to enhance the error characteristic. Simulation results verify the performance improvement of the proposed loop.

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Tu, Pingzhou. "Performance of an Interleaved Spread Spectrum OFDM System over Multipath Fading Channels." ECTI Transactions on Electrical Engineering, Electronics, and Communications 7, no. 1 (June 25, 2007): 1–13. http://dx.doi.org/10.37936/ecti-eec.200971.171797.

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In this paper we propose an interleaved spread spectrum orthogonal frequency division multiplexing (ISS-OFDM) system and investigate its performance over frequency selective multipath fading channels. The purpose is to exploit frequency diversity capability, develop an e±cient spectrum spreading algorithm and improve the system performance over frequency selective multipath fading channels. At transmitter, a spectrum spread ISS-OFDM signal is generated by employing OFDM modulation and interleaving techniques. At the receiver, two solutions including serial demodulation and parallel demodulation for diversity combing are proposed, in which the received signals are combined by using a maximum ratio combining (MRC) technique. The simulation indicates that higher frequency diversity is achieved, and the Bit Error Rate (BER) and Peak-to-Average Power Ratio (PAR) performances of the proposed ISS-OFDM system over frequency selective multipath fading channels are improved signi¯cantly as compared with the conventional OFDM systems. Another unique characteristic is that the spectrum spreading factor and diversity order provided by the system are reconfigurable to achieve cognitive communications.

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Dio Gangga Saskara, I. Putu, Nyoman Pramaita, and I. Gusti Agung Komang Diafari Djuni H. "DESAIN SIMULASI UNJUK KERJA BARKER CODE PADA KANAL FREQUENCY SELECTIVE FADING." Jurnal SPEKTRUM 9, no. 3 (September 29, 2022): 8. http://dx.doi.org/10.24843/spektrum.2022.v09.i03.p2.

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The signal that arrives at the receiving end is the sum of the various transmissions passed by the signal (multipath) which is influenced by the channel so that there is signal interference. Many innovations have been made so that the received signal can have high security, one of which is spread spectrum with a dual access scheme to increase the ability of many spectrum users in a limited number without disturbing one another. This simulation was tested with the aim of spreading the spectrum with different code lengths for the same bit length of information, and observed from the change in the BER value obtained from the MATLAB 2018a simulation results to find out how the barker code performance on the frequency selective fading channel on a single user. The analysis of this research is obtained from the simulation results in the form of a graph that shows the BER value compared to Eb/No. The BER value shown by the barker code performance on the flat fading channel, which is compared based on the existing flat theory, shows the graph trend and the BER value generated from the simulation is close to the theoretical flat BER value. The performance of the barker code on the frequency selective fading channel is carried out by varying the number of multipath components 7, 5, and 3. The simulation results show that multipath 3 is the best with the smallest bit error value compared to multipath 7 and 5. Barker code performance is strongly influenced by the number of multipath components, the more the number of multipath components, the more performance of the barker code bit error, and vice versa.

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Pradana, Zein Hanni, and Ade Wahyudin. "Analisis Optimasi Space Diversity pada Link Microwave Menggunakan ITU Models." Jurnal Elektro dan Telekomunikasi Terapan 4, no. 2 (March 12, 2018): 586. http://dx.doi.org/10.25124/jett.v4i2.1148.

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Dalam sebuah Link Microwave, sinyal terima harus memenuhi syarat LOS (Line of Sight). LOS adalah perambatan radio gelombang mikro dari antena pengirim ke antena penerima dengan jalur transmisi bebas. Pada penerima, sinyal yang diterima tidak hanya berasal dari sinyal LOS tetapi sinyal yang dipantulkan dari permukaan bumi. Sinyal dari beberapa pantulan ini sering disebut dengan multipath. Penerimaan sinyal di penerima memang merupakan sinyal penambahan dari sinyal LOS dan juga sinyal multipath, namun sinyal-sinyal multipath ini justru akan menimbulkan interferensi yang dapat menyebabkan fading atau perubahan gelombang elektromagnetik yang diterima. Untuk menanggulangi fading ini maka diperlukan optimasi yang meningkatkan kualitas Link Microwave. Dengan menggunakan space diversity menggunakan ITU models, availability meningkat dari 99,96949% menjadi 99,98767%. Diversity Receive Signal tertinggi didapatkan pada 200l, dengan nilai Diversity Receive Signal adalah -83,94dBm.

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Alabi, Oluwaseun Yinka, and 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, no. 2 (August 1, 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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Zainul Halim, Muhamad, Nyoman Pramaita, and Pande Ketut Sudiarta. "SIMULASI KINERJA GOLD CODE PADA SISTEM KOMUNIKASI DIRECT SEQUENCE SPREAD SPECTRUM (DSSS) MELALUI KANAL MULTIPATH FADING." Jurnal SPEKTRUM 8, no. 2 (July 12, 2021): 257. http://dx.doi.org/10.24843/spektrum.2021.v08.i02.p29.

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The communication channel cannot be separated from noise, interference and fading.To minimize mutual interference, you can use a scatter code. This research uses Gold Codewith a code length of 31. This simulation aims to determine the effect of the number of multipathcomponents on the Gold Code performance of multipath fading channels. This simulation usesdigital modulation, namely BPSK (Binary Phase Shift Keying). In the simulation of flat fadingchannel with 1 multipath component number, the results of the comparison of simulated BERwith theoretical BER are almost the same so that the simulation results can be said to be validand can be used on selective fading channels. In the simulation of frequency selective fadingchannels with variations of multipath components have different values, this happens due tointerference. In this simulation, the number of multipath 27 components that have the mostdisruptive signals results in the worst performance. In multi-user cross-correlation, it has poorperformance, seen from the cross-correlation function, where the correlation value of user 1with 2, 3 and 4 is more than 0, this value indicates the user is being interfered with by otherusers.

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Asif, Muhammad, Abid Yahya, Othman Sidek, Farid Ghani, and Umair Soori. "Frequency Hopping Overcomes Multipath Fading using FEC." International Conference on Electrical Engineering 6, no. 6 (May 1, 2008): 1–9. http://dx.doi.org/10.21608/iceeng.2008.34215.

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Lindhé, Magnus, and Karl Henrik Johansson. "Exploiting multipath fading with a mobile robot." International Journal of Robotics Research 32, no. 12 (October 2013): 1363–80. http://dx.doi.org/10.1177/0278364913486845.

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Lindhe, M., and K. Johansson. "Using robot mobility to exploit multipath fading." IEEE Wireless Communications 16, no. 1 (February 2009): 30–37. http://dx.doi.org/10.1109/mwc.2009.4804366.

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Baronkin, V. M., Y. V. Zakharov, and T. C. Tozer. "Frequency estimation in slowly fading multipath channels." IEEE Transactions on Communications 50, no. 11 (November 2002): 1848–59. http://dx.doi.org/10.1109/tcomm.2002.805275.

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Koch, Tobias, and Amos Lapidoth. "On Multipath Fading Channels at High SNR." IEEE Transactions on Information Theory 56, no. 12 (December 2010): 5945–57. http://dx.doi.org/10.1109/tit.2010.2080995.

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Paparisto, G., and K. M. Chugg. "PSP array processing for multipath fading channels." IEEE Transactions on Communications 47, no. 4 (April 1999): 504–7. http://dx.doi.org/10.1109/26.764922.

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45

Zhang, Y. S., and D. B. Li. "Volterra adaptive prediction of multipath fading channel." Electronics Letters 33, no. 9 (1997): 754. http://dx.doi.org/10.1049/el:19970529.

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Song, Hyoung-kyu. "Frequency offset estimator for multipath fading channels." Electronics Letters 35, no. 5 (1999): 380. http://dx.doi.org/10.1049/el:19990304.

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Sayeed, A. M., A. Sendonaris, and B. Aazhang. "Multiuser detection in fast-fading multipath environments." IEEE Journal on Selected Areas in Communications 16, no. 9 (1998): 1691–701. http://dx.doi.org/10.1109/49.737638.

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Chiavaccini, E., and G. M. Vitetta. "GQR models for multipath Rayleigh fading channels." IEEE Journal on Selected Areas in Communications 19, no. 6 (June 2001): 1009–18. http://dx.doi.org/10.1109/49.926357.

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Novaković, Dejan M., and Miroslav L. Dukić. "Multistage multiuser detector for multipath fading channel." European Transactions on Telecommunications 12, no. 6 (November 2001): 471–78. http://dx.doi.org/10.1002/ett.4460120603.

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Krstic, Dragana, Petar Nikolic, Danijela Aleksic, Sinisa Minic, Dragan Vuckovic, and Mihajlo Stefanovic. "Product of Three Random Variables and its Application in Relay Telecommunication Systems in the Presence of Multipath Fading." Journal of Telecommunications and Information Technology 1 (March 29, 2019): 83–92. http://dx.doi.org/10.26636/jtit.2019.130018.

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In this paper, the product of three random variables (RVs) will be considered. Distribution of the product of independent random variables is very important in many applied problems, including wireless relay telecommunication systems. A few of such products of three random variables are observed in this work: the level crossing rate (LCR) of the product of a Nakagami-m random variable, a Rician random variable and a Rayleigh random variable, and of the products of two Rician RVs and one Nakagami-m RV is calculated in closed forms and presented graphically. The LCR formula may be later used for derivation of average fade duration (AFD) of a wireless relay communication radio system with three sections, working in the multipath fading channel. The impact of fading parameters and multipath fading power on the LCR is analyzed based on the graphs presented.

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Journal articles on the topic 'Multipath fading'

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