Articoli di riviste: "FADING ENVIRONMENTS"

1

Frolik, Jeff. "A Practical Metric for Fading Environments". IEEE Wireless Communications Letters 2, n. 2 (aprile 2013): 195–98. http://dx.doi.org/10.1109/wcl.2013.011713.120853.

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2

Kim, Minhyuk, e Sekchin Chang. "A real-time locating system for localization of high-speed mobile objects". International Journal of Distributed Sensor Networks 14, n. 5 (maggio 2018): 155014771877447. http://dx.doi.org/10.1177/1550147718774475.

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Abstract (sommario):

This article addresses a novel real-time locating system for localization of high-speed mobile objects in fading environments. The proposed locating system exploits time difference of arrival measurements based on ultra-wideband signals. However, the ultra-wideband signals cause a frequency-selective fading due to their short time duration, which induces severe inter-symbol interference. Moreover, high-speed objects cause fast fading due to large Doppler spread. Therefore, the fading cases considerably reduce the localization performance. The presented locating system relies on a new localization approach in order to overcome the fading issues, which utilizes a modification of extended Kalman filtering. Especially, the suggested locating method works well even in the zero time difference of arrival case, which occurs due to a very deep fading. Experiment results verify that the proposed real-time locating system gives excellent localization performance in severe fading environments. The results also exhibit that the presented locating system is superior to the conventional locating systems in the localization of high-speed mobile objects under fading environments.

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Bhutto, Zuhaibuddin, e Wonyong Yoon. "Dual-Hop Cooperative Relaying with Beamforming Under Adaptive Transmission in κ–μ Shadowed Fading Environments". Electronics 8, n. 6 (11 giugno 2019): 658. http://dx.doi.org/10.3390/electronics8060658.

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In this paper, we analyze the performance of a dual-hop cooperative decode-and-forward (DF) relaying system with beamforming under different adaptive transmission techniques over κ − μ shadowed fading channels. We consider multiple antennas at the source and destination, and communication takes place via a single antenna relay. The published work in the literature emphasized the performance analysis of dual-hop DF relaying systems, in conjunction with different adaptive transmission techniques for classical fading channels. However, in a real scenario, shadowing of the line-of-sight (LoS) signal is caused by complete or partially blockage of the LoS by environmental factors such as trees, buildings, mountains, etc., therefore, transmission links may suffer from fading as well as shadowing, either concurrently or separately. Hence, the κ − μ shadowed fading model was introduced to emulate such general channel conditions. The κ − μ shadowed fading model is a general fading model that can perfectly model the fading and shadowing effects of the wireless channel in a LoS propagation environment, and it includes some classical fading models as special cases, such as κ − μ , Rician, Rician-shadowed, Nakagami- m ^ , One-sided Gaussian, and Rayleigh fading. In this work, we derive the outage probability and average capacity expressions in an analytical form for different adaptive transmission techniques: (1) optimal power and rate adaptation (OPRA); (2) optimal rate adaptation and constant transmit power (ORA); (3) channel inversion with a fixed rate (CIFR); and (4) truncated channel inversion with a fixed rate (TIFR). We evaluate the system performance for different arrangements of antennas and for different fading and shadowing parameters. The obtained analytical expressions are verified through extensive Monte Carlo simulations.

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Chen, Joy Iong-Zong, Kai-Chih Chuang, Ching-Chuan Chiu e Deng-Jyi Juang. "On Two-Tier Femtocell over Fading Environments". Engineering 03, n. 03 (2011): 292–99. http://dx.doi.org/10.4236/eng.2011.33034.

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Ferreira, Manuel M., Slawomir J. Ambroziak, Filipe D. Cardoso, Jaroslaw Sadowski e Luis M. Correia. "Fading Modeling in Maritime Container Terminal Environments". IEEE Transactions on Vehicular Technology 67, n. 10 (ottobre 2018): 9087–96. http://dx.doi.org/10.1109/tvt.2018.2855413.

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6

Chen, Yen-Chih, e Yu Su. "MIMO channel estimation in correlated fading environments". IEEE Transactions on Wireless Communications 9, n. 3 (marzo 2010): 1108–19. http://dx.doi.org/10.1109/twc.2010.03.081603.

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7

Sayeed, A. M., A. Sendonaris e B. Aazhang. "Multiuser detection in fast-fading multipath environments". IEEE Journal on Selected Areas in Communications 16, n. 9 (1998): 1691–701. http://dx.doi.org/10.1109/49.737638.

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8

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, n. 10 (31 ottobre 2021): 34–39. http://dx.doi.org/10.46501/ijmtst0710005.

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Abstract (sommario):

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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Joo, Jung Suk. "On the Use of Polar Code for LoRa PHY". International Research Journal of Computer Science 10, n. 01 (31 gennaio 2023): 01–03. http://dx.doi.org/10.26562/irjcs.2023.v1001.01.

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LoRa (long range) PHY adopts simple hamming codes with maximum one-bit error correction capacity, which is one of the main causes of poor performance in fading environments. As one approach to improve performance in fading environments, in this paper, we will investigate the use of a polar code for LoRa. Specifically, through computer simulations, we will compare the performance gain in Rician fading channels according to the application of a polar code with code rate 0.5 instead of the original (8,4) hamming code in LoRa PHY.

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10

Cheng, Weijun, e Teng Chen. "Dual-Hop Fixed Gain Relaying Transmissions with Semi-Blind in Asymmetric Multipath/Shadowing Fading Channels". Open Electrical & Electronic Engineering Journal 9, n. 1 (18 marzo 2015): 82–90. http://dx.doi.org/10.2174/1874129001509010082.

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In this paper, we investigate the end-to-end performance of a dual-hop fixed gain relaying system with semiblind relay under asymmetric fading environments. In such environments, the wireless links of the considered system undergo asymmetric multipath/shadowing fading conditions, where one link is subject to only the Nakagami-m fading, the other link is subject to the composite Nakagami-lognormal fading which is approximated by using mixture gamma fading model. First, the cumulative distribution function (CDF), the moment generating function (MGF) and the moments of the end-to-end signal-to-noise ratio (SNR) are derived under two asymmetric scenarios. Then, novel closed-form expressions of the outage probability, the average end-to-end SNR, the symbol error rate and the ergodic capacity for the dual-hop system are obtained based on the CDF and the MGF, respectively. Finally, some numerical and simulation results are shown and discussed to validate the accuracy of the analytical results under different scenarios, such as varying average SNR, fading parameters per hop, the choice of the semi-blind gain and the location of relaying nodes.

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11

Ebrahimzadeh, Ataollah, e Gholam Reza Ardeshir. "A New Signal Type Classifier for Fading Environments". Journal of Computing and Information Technology 15, n. 3 (2007): 257. http://dx.doi.org/10.2498/cit.1000874.

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12

Al-Semari, S. A., e M. Guizani. "Capacity of slotted ALOHA in generalised fading environments". Electronics Letters 32, n. 22 (1996): 2046. http://dx.doi.org/10.1049/el:19961395.

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13

Ghasemi, Amir, e Elvino Sousa. "Fundamental limits of spectrum-sharing in fading environments". IEEE Transactions on Wireless Communications 6, n. 2 (febbraio 2007): 649–58. http://dx.doi.org/10.1109/twc.2007.05447.

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14

Lee, Gun-Ho, e Eui-Rim Jeong. "Split Channel Two-Tone On-Off Keying for Internet of Things Communication in Fading Channel". Journal of Computational and Theoretical Nanoscience 17, n. 7 (1 luglio 2020): 3207–11. http://dx.doi.org/10.1166/jctn.2020.9162.

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In medical treatment, healthcare and home appliances, the demand for Internet of Things (IoT) services is increasing in urban areas. However, in fading environments of urban area, the existing IoT communication system can degrade severely. The purpose of this paper is to develop a new IoT communication technology that improves communication performance in fading channels. IoT communication systems are aiming at low power long distances. In addition, the amount of data transmission is small due to the service requirements. To achieve this goal, existing IoT communication modems are designed with narrowband signals. However, narrowband signals may cause performance degradation in a frequency selective fading channel environments in urban area. In this paper, we propose a split channel two tone OOK (SC-TT-OOK) that implements on-off keying (OOK) using two tones. Unlike the existing OOK by using one tone, SC-TT-OOK uses spaced two tones to improve communication performance in fading channels. The conventional OOK method has a similar characteristic to that of the existing IoT modems with a narrow bandwidth spectrum. The proposed SC-TT-OOK is OOK using two separated tones. Since the proposed modulation uses two tones, it requires twice the frequency resources of the conventional OOK. However, if the frequencies of the two tones are sufficiently spaced apart, frequency diversity gain can be achieved in the frequency selective fading channels, and communication reliability can be improved in urban environments. The proposed SC-TT-OOK is examined through computer simulation. The simulation results show that the proposed scheme outperforms the conventional scheme in the frequency selective fading channel. Therefore, the proposed method can be used as an alternative technique for IoT modem in urban environments.

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15

Chaikalis, Costas. "Efficient TTI for 3G Multimedia Applications". Advances in Multimedia 2007 (2007): 1–7. http://dx.doi.org/10.1155/2007/95474.

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Time transmission interval (TTI) or outer block interleaving is an important task for the implementation of UMTS turbo coding in flat Rayleigh fading environment. An efficient TTI choice can save computational complexity. However, different multimedia scenarios are investigated using the maximum UMTS frame length, and simulation results are presented for the four possible outer block interleaver configurations in the case of flat Rayleigh fading channel. It is shown that different operating environments require an appropriate TTI in terms of bit error rate (BER) performance for the following data rates: 28.8 kbps, 64 kbps, 144 kbps, 384 kbps, and 2 Mbps.

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16

Valenzuela-Valdes, J. F., M. F. Manzano e L. Landesa. "Evaluation of True Polarization Diversity in Rician-Fading Environments". IEEE Antennas and Wireless Propagation Letters 11 (2012): 775–78. http://dx.doi.org/10.1109/lawp.2012.2205550.

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17

Valenzuela-Valdes, J. F., A. M. Martinez-Gonzalez e D. A. Sanchez-Hernandez. "Emulation of MIMO Nonisotropic Fading Environments With Reverberation Chambers". IEEE Antennas and Wireless Propagation Letters 7 (2008): 325–28. http://dx.doi.org/10.1109/lawp.2008.928488.

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18

Kambara, Keiichi, Hiroshi Nishimoto, Toshihiko Nishimura, Takeo Ohgane e Yasutaka Ogawa. "Subblock processing in MMSE-FDE under fast fading environments". IEEE Journal on Selected Areas in Communications 26, n. 2 (2008): 359–65. http://dx.doi.org/10.1109/jsac.2008.080212.

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19

Kurien, Binoy G. "Collaborative and Passive Channel Gain Estimation in Fading Environments". IEEE Transactions on Cognitive Communications and Networking 5, n. 4 (dicembre 2019): 863–72. http://dx.doi.org/10.1109/tccn.2019.2922315.

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20

Mota, Kim Moraes, Wanessa de Alvarenga Silva, Luan Carlos de S. M. Ozelim, Leticia Moreira Vale, Ugo Silva Dias e Pushpa Narayan Rathie. "Spectrum sharing systems capacity under η-μ fading environments". Journal of the Franklin Institute 356, n. 12 (agosto 2019): 6741–56. http://dx.doi.org/10.1016/j.jfranklin.2019.05.037.

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21

PHUA, VALANCE, e AMITAVA DATTA. "A LINK STATE DEPENDENT TDMA PROTOCOL FOR INDUSTRIAL WIRELESS SENSOR NETWORK APPLICATIONS IN PERIODICALLY CHANGING ENVIRONMENTS". Journal of Interconnection Networks 09, n. 03 (settembre 2008): 231–54. http://dx.doi.org/10.1142/s0219265908002254.

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Existing TDMA-based MAC protocols for wireless sensor networks are not specifically built to consider communication channels that are prone to fading. We describe the impact of periodically changing environment on small-scale fading effects in industrial indoor wireless networks. Using a site-specific ray tracer, we show that the position of nodes and the periodic movements of objects with constant velocities in the environment have significant impact on signal fading. Finding that fading is approximately periodic, we propose a TDMA-based MAC protocol for wireless sensor networks built for industrial applications that uses link state dependent scheduling. In our approach, nodes gather samples of the channel quality and generate prediction sets from the sample sets in independent slots. Using the prediction sets, nodes only wake up to transmit/receive during scheduled slots that are predicted to be clear and sleep during scheduled slots that may potentially cause a transmitted signal to fade. We simulate our proposed protocol and compare its performance with the well published Z-MAC protocol. We found that our protocol significantly improves packet throughput and energy consumption as compared to Z-MAC. We also found that in conditions which are not perfect under our assumptions, the performance of our protocol degrades gracefully.

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22

Wang, Jun Feng, Yue Cui, Jian Fu Teng e Xiu Rong Ma. "Doppler Shift Estimation for TD-SCDMA System over Railway Environments". Applied Mechanics and Materials 195-196 (agosto 2012): 115–20. http://dx.doi.org/10.4028/www.scientific.net/amm.195-196.115.

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In this paper, a new Doppler shift estimator is proposed for Time Division-Synchronous Code Division Multiple Access (TD-SCDMA) over railway environments. Different from other existing methods, which commonly assume that the fading channel coefficients are available for the Doppler estimators, the proposed estimator is developed based on the signals which contain unknown frequency selective fading channel coefficients, unknown Rice factor and random receiver noise; it contains three steps. The statistical properties of the training symbols which are called near independent identically distributed (i.i.d.) training sequences, i.e., midamble, are first analyzed. Afterwards, by the help of a training sequence, the second-order and fourth-order statistics of the received signals are calculated. Then, by exploiting these statistical results, the Doppler shift estimator is obtained. The proposed estimator employs a smoothing function with corrective factor. By optimizing the corrective factor, an accuracy solution is acquired within the Doppler shift range of possibilities. Simulation results indicate that the proposed estimator is greatly reliable and effective to estimate Doppler shift up to 400 Hz.

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23

Ashraf, Umer, e Ghulam Rasool Begh. "BER ANALYSIS IN NON-HOMOGENEOUS FADING ENVIRONMENTS WITH IMPULSIVE NOISE". Progress In Electromagnetics Research M 101 (2021): 197–206. http://dx.doi.org/10.2528/pierm21020801.

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24

Qin, Dong, Yuhao Wang e Tianqing Zhou. "Average SEP of AF Relaying in Nakagami-m Fading Environments". Wireless Communications and Mobile Computing 2018 (2018): 1–7. http://dx.doi.org/10.1155/2018/6581827.

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This paper is devoted to an investigation of an exact average symbol error probability (SEP) for amplify and forward (AF) relaying in independent Nakagami-m fading environments with a nonnegative integer plus one-half m, which covers many actual scenarios, such as one-side Gaussian distribution (m=0.5). Using moment generating function approach, the closed-form SEP is expressed in the form of Lauricella multivariate hypergeometric function. Four modulation modes are considered: rectangular quadrature amplitude modulation (QAM), M-ary phase shift keying (MPSK), M-ary differential phase shift keying (MDPSK), and π/4 differential quaternary phase shift keying (DQPSK). The result is very simple and general for a nonnegative integer plus one-half m, which covers the same range as integer m. The tightness of theoretical analysis is confirmed by computer simulation results.

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25

Mathar, R., J. Mattfeldt e R. Hager. "Analysis of mobile packet radio networks in Rayleigh fading environments". IEEE Transactions on Vehicular Technology 43, n. 4 (1994): 1112–17. http://dx.doi.org/10.1109/25.330175.

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26

Svasti-Xuto, U., Qiang Wang e V. K. Bhargava. "Capacity of an FH-SSMA system in different fading environments". IEEE Transactions on Vehicular Technology 47, n. 1 (1998): 75–83. http://dx.doi.org/10.1109/25.661034.

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27

Đošić, Danijel, Časlav Stefanović, Dejan Milić e Mihajlo Stefanović. "System performances of SC reception in asymmetric multipath fading environments". University Thought - Publication in Natural Sciences 9, n. 2 (2019): 56–62. http://dx.doi.org/10.5937/univtho9-21769.

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28

Karasawa, Y., e H. Iwai. "Formulation of spatial correlation statistics in Nakagami-Rice fading environments". IEEE Transactions on Antennas and Propagation 48, n. 1 (2000): 12–18. http://dx.doi.org/10.1109/8.827380.

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29

Musavian, L., e S. Aïssa. "Outage-constrained capacity of spectrum-sharing channels in fading environments". IET Communications 2, n. 6 (2008): 724. http://dx.doi.org/10.1049/iet-com:20070477.

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30

Sipal, V., J. Gelabert, B. Allen, C. Stevens e D. Edwards. "Frequency-selective fading of ultrawideband wireless channels in confined environments". IET Microwaves, Antennas & Propagation 5, n. 11 (2011): 1328. http://dx.doi.org/10.1049/iet-map.2010.0511.

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31

Rao, Anlei, e Mohamed-Slim Alouini. "Performance of Cooperative Spectrum Sensing over Non-Identical Fading Environments". IEEE Transactions on Communications 59, n. 12 (dicembre 2011): 3249–53. http://dx.doi.org/10.1109/tcomm.2011.082911.100222.

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32

Zummo, S. A., e W. E. Stark. "Error probability of coded STBC systems in block fading environments". IEEE Transactions on Wireless Communications 5, n. 5 (maggio 2006): 972–77. http://dx.doi.org/10.1109/twc.2006.1633348.

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33

Jayakrishnan, Sarma Sandeep, e Vidhyacharan Bhaskar. "Performance analysis of MIMO–OFDM in various outdoor fading environments". AEU - International Journal of Electronics and Communications 66, n. 10 (ottobre 2012): 797–805. http://dx.doi.org/10.1016/j.aeue.2012.01.013.

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34

Kim, Yoora, e Sungoh Kwon. "Capacity Analysis of Opportunistic Scheduling in Nakagami- $m$ Fading Environments". IEEE Transactions on Vehicular Technology 64, n. 11 (novembre 2015): 5379–84. http://dx.doi.org/10.1109/tvt.2014.2378282.

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35

Siddakatte, Ranjeeth Kumar, Ali Broumandan e Gérard Lachapelle. "Enhanced GNSS Signal Tracking in Fading Environments using Frequency Diversity". Navigation 64, n. 2 (giugno 2017): 213–29. http://dx.doi.org/10.1002/navi.193.

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36

Le, Khoa N., e Kishor P. Dabke. "Channel capacity of OFDM systems employing diversity in fading environments". Wireless Communications and Mobile Computing 12, n. 17 (1 febbraio 2011): 1493–516. http://dx.doi.org/10.1002/wcm.1078.

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37

Hussain, Arif, Hina Magsi, Arslan Ahmed, Hadi Hussain, Zahid Hussain Khand e Faheem Akhtar. "The effects of using variable lengths for degraded signal acquisition in GPS receivers". International Journal of Electrical and Computer Engineering (IJECE) 11, n. 4 (1 agosto 2021): 3201. http://dx.doi.org/10.11591/ijece.v11i4.pp3201-3211.

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The signal acquisition in GPS receivers is the first and very crucial process that may affect the overall performance of a navigation receiver. Acquisition program initiates a searching operation on received navigation signals to detect and identify the visible satellites. However, signal acquisition becomes a very challenging task in a degraded environment (i.e, dense urban) and the receiver may not be able to detect the satellites present in radio-vicinity, thus cannot estimate an accurate position solution. In such environments, satellite signals are attenuated and fluctuated due to fading introduced by Multipath and NLOS reception. To perform signal acquisition in such degraded environments, larger data accumulation can be effective in enhancing SNR, which tradeoff huge computational load, prolonged acquisition time and high cost of receiver. This paper highlights the effects of fading on satellite signal acquisition in GPS receiver through variable data lengths and SNR comparison, and then develops a statistical relationship between satellite visibility and SNR. Furthermore it also analyzes/investigates the tradeoff between computation load and signal data length.

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Rodrigo-Peñarrocha, Vicent M., Juan Reig, Lorenzo Rubio, Herman Fernández e Susana Loredo. "Analysis of Small-Scale Fading Distributions in Vehicle-to-Vehicle Communications". Mobile Information Systems 2016 (2016): 1–7. http://dx.doi.org/10.1155/2016/9584815.

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This work analyzes the characteristics of the small-scale fading distribution in vehicle-to-vehicle (V2V) channels. The analysis is based on a narrowband channel measurements campaign at 5.9 GHz designed specifically for that purpose. The measurements were carried out in highway and urban environments around the city of Valencia, Spain. The experimental distribution of the small-scale fading is compared to several analytical distributions traditionally used to model the fast fading in wireless communications, such as Rayleigh, Nakagami-m, Weibull, Rice, andα-μdistributions. The parameters of the distributions are derived through statistical inference techniques and their goodness-of-fit is evaluated using the Kolmogorov-Smirnov (K-S) test. Our results show that theα-μdistribution exhibits a better fit compared to the other distributions, making its use interesting to model the small-scale fading in V2V channels.

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Sadowski, Jaroslaw. "Measurement of Coherence Bandwidth in UHF Radio Channels for Narrowband Networks". International Journal of Antennas and Propagation 2015 (2015): 1–11. http://dx.doi.org/10.1155/2015/985892.

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This paper presents results of investigation on the coherence bandwidth of narrowband radio channels in 430 MHz band. The coherence bandwidth values were estimated from a power delay profile obtained by recording CDMA2000 forward channel signals during real-field measurements in various environments: medium city, flat terrain, and hilly terrain in northern Poland. The results of measurements are compared with characteristic parameters of UHF radio channel models defined for exemplary narrowband digital system from the TETRA standard. In all of the tested environments, the coherence bandwidth values during most of an observation time were much higher than 25 kHz. Therefore, the fading in tested UHF narrowband channels should be classified as flat fading.

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Zhou, Tao, Cheng Tao, Liu Liu e Zhenhui Tan. "A Semiempirical MIMO Channel Model in Obstructed Viaduct Scenarios on High-Speed Railway". International Journal of Antennas and Propagation 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/287159.

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A semiempirical multiple-input multiple-output (MIMO) channel model is proposed for high-speed railway (HSR) viaduct scenarios. The proposed MIMO model is based on the combination of realistic single-input single-output (SISO) channel measurement results and a theoretical geometry-based stochastic model (GBSM). Temporal fading characteristics involvingK-factor and Doppler power spectral density (PSD) are derived from the wideband measurement under an obstructed viaduct on Zhengzhou-Xi’an HSR in China. The GBSM composed of a one-ring model and an elliptical model is employed to describe the entire propagation environment. Environment-related parameters in the GBSM are determined by the measured temporal fading properties. And a close agreement is achieved between the model results and measured data. Finally, a deterministic simulation model is established to perform the analysis of the space-time correlation function, the space-Doppler PSD, and the channel capacity for the measured scenario. This model is more realistic and particularly beneficial for the performance evaluation of MIMO systems in HSR environments.

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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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Sadrieh, Seyed Nima, Ali Broumandan e Gérard Lachapelle. "Doppler Characterization of a Mobile GNSS Receiver in Multipath Fading Channels". Journal of Navigation 65, n. 3 (4 aprile 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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KAMBARA, Keiichi, Hiroshi NISHIMOTO, Toshihiko NISHIMURA, Takeo OHGANE e Yasutaka OGAWA. "Subblock Processing for Frequency-Domain Turbo Equalization under Fast Fading Environments". IEICE Transactions on Communications E92-B, n. 5 (2009): 1466–74. http://dx.doi.org/10.1587/transcom.e92.b.1466.

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Zhang, Lingwen, Chang Liu, Jiayi Zhang, Faen Wu e Wenkao Yang. "Performance of relay networks in fading environments with dominant specular components". China Communications 13, n. 12 (dicembre 2016): 69–78. http://dx.doi.org/10.1109/cc.2016.7897556.

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Wilson, D. Keith, Rafael Bey‐Hernandez e Vladimir E. Ostashev. "Statistical models for fading and coherence of sound in urban environments". Journal of the Acoustical Society of America 120, n. 5 (novembre 2006): 3336–37. http://dx.doi.org/10.1121/1.4781306.

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Hoang, Duong, e Ronald A. Iltis. "Performance evaluation of multi-hop csma/ca networks in fading environments". IEEE Transactions on Communications 56, n. 1 (gennaio 2008): 112–25. http://dx.doi.org/10.1109/tcomm.2008.050045.

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Sanchez-Heredia, Juan D., Juan F. Valenzuela-Valdes, Antonio M. Martinez-Gonzalez e David A. Sanchez-Hernandez. "Emulation of MIMO Rician-Fading Environments With Mode-Stirred Reverberation Chambers". IEEE Transactions on Antennas and Propagation 59, n. 2 (febbraio 2011): 654–60. http://dx.doi.org/10.1109/tap.2010.2096185.

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Xu, Feng, e Dian Wu Yue. "Analytical performance evaluation of dual-hop cooperative communication under fading environments". International Journal of Systems, Control and Communications 3, n. 1 (2011): 19. http://dx.doi.org/10.1504/ijscc.2011.039223.

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Broumandan, A., J. Nielsen e G. Lachapelle. "Signal detection performance in Rayleigh fading environments with a moving antenna". IET Signal Processing 4, n. 2 (2010): 117. http://dx.doi.org/10.1049/iet-spr.2009.0050.

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Soni, Sanjay Kumar, Priyanka Jain e Pappu Kumar Verma. "Modelling and performance evaluation over Nakagami-m/log-normal fading environments". International Journal of Communication Networks and Distributed Systems 23, n. 4 (2019): 452. http://dx.doi.org/10.1504/ijcnds.2019.10024113.

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