Dissertations / Theses: 'Multipath fading'

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Menemenlis, Nickie. "Stochastic models for multipath fading channels." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=38505.

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The main contribution of this work is to extend the present multi-path fading channel (MFC) models in two directions.
First, the wireless communication system is viewed as a dynamical system where the channel constitutes the main plant of such a system. The random variables characterizing the magnitude of each multi-path component are generalized to random processes with time-varying statistics. It is claimed that the dynamics of both the log-normal shadowing and short-term fading channels is captured by the use of stochastic diffusion processes which emerge from mean-reverting Ornstein-Uhlenbeck processes, implying that signal envelope variations can be modeled using stochastic differential equations. Explicit expressions for signal envelope distributions and second order statistics of the received signal are derived.
Further, the short-term dynamical model is cast into a state-space representation and a nominal model is derived, based on which robust analysis and design can be performed in order to capture additional channel uncertainties.
The dynamical channel models introduced here are in accordance of the physical principles of electromagnetic wave propagation, they are parametric and able to describe diverse propagation environments.
Second, a unified statistical analysis framework is introduced in order to compute the various statistics, second-order properties and densities of the overall received signal of the MFC's. To this end, the MFC model is formulated as a general shot-noise process brought forward by Rice. By extending and adapting the shot-noise analysis to complex signals the statistics of the overall received signal are derived, with explicit computations of the various moments and second-order statistics. The analysis includes the case of moving scatters (i.e. rain droplets) which it is shown to affect the dynamical temporal characteristics of the channel. It is also shown here that samples of the received signal approach a jointly Gaussian density, as certain parameters tend to their limits. Further, when the density of the received signal does not approach the Gaussian density, the Edgeworth series expansion is employed to compute the non-Gaussian density. This analysis brings forward the parameters responsible for Gaussianity of the received signal, parameters which designers can use in order to tailor their transmitter/receiver design. (Abstract shortened by UMI.)

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Jefferis, Robert. "IN-SERVICE DETECTION OF MULTIPATH FADING." International Foundation for Telemetering, 2002. http://hdl.handle.net/10150/605607.

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International Telemetering Conference Proceedings / October 21, 2002 / Town & Country Hotel and Conference Center, San Diego, California
Multipath (MP) fading is the dominant channel impairment in many aeronautical telemetry links. One product of a recent multipath mitigation study is the discovery of a simple technique for detecting its presence over a useful range of conditions. The technique also detects significant random noise levels in the channel. This paper describes the “Signal Degradation Indicator” (SDI) and its application to FQPSK-B and SOQPSK [2] modulation. Laboratory emulation data is presented and implementation considerations are discussed.

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Zhou, Bin. "Mobile velocity estimation in multipath fading channels." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0005/MQ42710.pdf.

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Lei, Qiang, and Michael Rice. "Iterative Equalization for SOQPSK in Multipath Fading." International Foundation for Telemetering, 2008. http://hdl.handle.net/10150/606195.

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ITC/USA 2008 Conference Proceedings / The Forty-Fourth Annual International Telemetering Conference and Technical Exhibition / October 27-30, 2008 / Town and Country Resort & Convention Center, San Diego, California
This paper investigates the application of iterative equalization techniques to overcome multipath fading for shaped offset QPSK (SOQPSK) in aeronautical telemetry. Two iterative equalization techniques for turbo encoded SOQPSK are presented. The first is the optimal-MAP turbo equalizer for OQPSK. The second equalizer is the adaptive decision feedback equalizer. Simulation shows that in the presence of frequency selective multipath typically encountered in aeronautical telemetry, both of these equalizers exhibit impressive performance.

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Samuel, Rajkumar. "Modeling of multipath fading channels for network simulation." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1293.

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Chang, Ihn Kiel. "Antijam spread-spectrum communications over multipath-fading channels." Diss., Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/15453.

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7

Zhang, Tingting. "Space time transceiver design over multipath fading channels." Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/11964.

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The objective of the study is to develop novel space-time transceivers for OS-COMA (DirectSequence Code Division Multiple Access) arrayed MIMO (Multiple-Input Multiple-Output) systems operating in multiple-access multipath fading channels. The ever increasing demand for performance and capacity in cellular wireless systems has prompted the development of OS-COMA MIMO systems. Unlike other reported research on MIMO systems which often .assumes the use of multiple antennas, in this thesis, arrayed MIMO system frameworks are proposed, which, by harnessing the geometrical information of the antenna arrays and received signals, provide a richer description of the channel characteristics and additional degrees offreedom in designing communication systems. Firstly, the framework of MIMO arrayed system in a OS-COMA system is developed. Subspace type blind channel estimator and receiver based on Doppler Spatial-Temporal Array (Doppler-STAR) are developed for time varying frequency selective fading channels, providing the system with more accurate channel estimation, higher resolution and superior interference cancellation capabilities. Secondly, joint transmitter and receiver optimisation in multipath and multiple access downlink system is studied. The two dimensional Spatio-Temporal Array manifold matrix (STAR matrix) is introduced. An iterative and a closed-form solution are proposed to solve the optimisation problem of minimising the MSE over the entire network. The proposed schemes offer a performance advantage over transmitter only (Tx-beamforming) and receiver only (Rx-beamforming) beamforming techniques under the system framework. Finally, the framework of an OFOM-CDMA arrayed system is developed. With the aid of Circular Spatial-Temporal ARray (C-STAR) manifold vector, two types of receivers (Le. preFFT and post.;FFT) are proposed-to eliminate the effect of multiple access interference (MAl) and inter-symbol interference (lSI) in a comp,letely blind way.

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Xiao, Heng. "On Modeling of a Mobile Multipath Fading Channel." PDXScholar, 1994. https://pdxscholar.library.pdx.edu/open_access_etds/5054.

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Multipath fading is one of the major practical concerns in wireless communications. A multipath transmission takes place when a transmitted signal arrives at a receiver by two or more paths of different delay. Such multiple paths may be due to atmospheric reflection or refraction, or reflections from buildings or other objects. A multipath fading channel is usually modeled as a time-variant tapped delay system. RAKE receiver can be used to detect the signal from the multipath fading channel. However, the number of delay taps, the time delay of each path, and the tap weight for each delay path need to be determined. The objective of this thesis is to explore the possibility of using the advance signal processing algorithms to estimate the number of delays, the time delay of each path, and the tap weight for each delay path in multipath channels and to investigate the performance of the RAKE receiver based on chip rate channel estimates in a realistic mobile environment. Simulations show that the new approach outperforms the existing approaches.

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吳萬雄 and Man-hung Ng. "Bandwidth-efficient pilot-symbol-aided techniques for fading estimation in multipath fading channels." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31242212.

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Ng, Man-hung. "Bandwidth-efficient pilot-symbol-aided techniques for fading estimation in multipath fading channels." Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk/hkuto/record.jsp?B22582174.

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Mella, Kristian. "Theory, Simulation and Measurement of Wireless Multipath Fading Channels." Thesis, Norwegian University of Science and Technology, Department of Electronics and Telecommunications, 2007. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-8713.

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Multipath fading is a very common phenomenon in signal transmission over wireless channels. When a signal is transmitted over multipath channels, it is subject to reflection, diffraction and refraction. This results in multiple versions of the same signal to arrive at the receiver, each of which has suffered from various path loss, time-delay, phase shift and often also frequency shift. The latter is a result of Doppler shifts, which is experienced whenever a relative movement between the receiver and transmitter or scatterers is present. The communication environment changes quickly over location or time, thus introducing uncertainties to the channel response. Such channels result in increased system complexity, and the propagation effects need to be identified in order to predict the channel behaviour. Path loss is experienced in all types of radio channels, and its metrics are often determined by empirical path loss models. The path loss effects the mean received signal level, whereas large-scale fading (Shadowing) results in large-scale fluctuations of this received level. These variations are superimposed by the small-scale fluctuations, or small-scale fading, caused by multipath reception and Doppler shifts. Small-scale fading is simulated to gain a better understanding of these effects. In order to observe these effects satisfactory, the whole digital radio communication system chain must be simulated. Simulations are also performed for estimating the data capacity over both mobile and fixed multipath channels, and the resulting capacity of multipath reception exceeds the capacity of a flat channel due to increased received energy. In order to classify the effect of multipath channels on signal transmission, the profile of the channel for a given scenario has to be known, i.e. channel metrics such as the RMS delay spread is essential for a successful radio system design. A multipath channel profile and its RMS delay spread can be derived from a vast number of channel measurements performed for a given scenario. Measurements on the multipath channel impulse response have been performed, RMS delay spread has been calculated, and the procedure of the channel measurement process itself is simulated in Matlab.

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Abboud, Nagi N. "Receiver structures and performance analysis for fading multipath channels." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=69781.

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In this research, we introduce a model for a fading multipath channel. The channel impulse response consists of an infinite series of $ delta$-functions whose amplitude has a Ricean probability density function and whose phases are randomly distributed. The arrival times of the various pulses follow a non-homogeneous Poisson process. This model is well structured and quite flexible for characterization of mobile and indoor radio environment. A Bayesian decision approach is employed for the derivation of the optimal receiver for this channel model with additive white Gaussian noise (AWGN). Simplified forms of the receiver are presented under assumption of high and low SNR. The performance of the system is investigated for the high SNR case when the intensity of the Poisson process is constant. In this case, the performance of this system is compared to what has been found for differential phase shift keying (DPSK) when using diversity reception. A performance analysis is also done for a more realistic situation when the rate of the Poisson process is a decaying oscillatory function. This non-homogeneous Poisson process generates the observed phenomenon of ray clustering.

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Yang, Jie. "Spreading sequence design for relay networks under multipath fading." Diss., Wichita State University, 2014. http://hdl.handle.net/10057/10946.

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Multipath frequency-selective fading can degrade the performance of a wireless communication system significantly as the data rate increases, e.g., when the data rate is as high as those of systems beyond long-term evolution (LTE)-Advanced. An effective method to combat multipath fading is a code division multiple access (CDMA) scheme. The objective of this dissertation is to present an effective method in designing nonbinary, secure, and optimum spreading and despreading pseudo noise (PN) sequences for CDMA multi-relay networks under frequency-selective fading by employing a maximum signal-to-interference-plus-noise ratio (SINR) criterion. This dissertation assumes that channel state information (CSI) is known at a central station such as a cloud radio access network (CRAN), which computes the optimum PN sequences and forwards them to both sources and destinations. This dissertation considers both partially and fully connected relay networks consisting of multiple sources, multiple relays, and multiple destinations. Direct links from sources to destinations are available in fully connected relay networks, whereas they are not available in partially connected relay networks. This dissertation also finds the optimum PN spreading and despreading sequences jointly and iteratively using the proposed novel method for multiple sources and destinations. Furthermore, it examines the sensitivity of the proposed schemes to imperfect CSI and wideband jamming. Simulation results verify that the proposed method can effectively improve system performance and can converge much faster in finding optimum PN sequences jointly for multiple sources and destinations than existing schemes under the same environment.
Thesis (Ph.D.)-- Wichita State University, College of Engineering, Dept. of Electrical Engineering and Computer Science

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Noon, David P. Jr. "Performance of a wideband CDMA system under multipath fading." Thesis, Virginia Tech, 1987. http://hdl.handle.net/10919/45825.

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The objective of this thesis is to determine the average probability of bit error of an asynchronous, noncoherent, direct-sequence, code-division multiple-access (CDMA) system using wideband M-ary FSK as bandpass modulation. The immediate analysis and determination of the average probability of bit error is made inherently more difficult because of two random effects. The first disturbance encountered in the analysis is the existence of additive, white, Gaussian noise and multi-user noise. The second disturbance, which is more difficult to analyze, is the effect of multipath fading, which is caused by reflections of the transmitted signal through the propagating medium to the receiver.

Master of Science

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Said, Nezar Ali. "Performance analysis of multi-carrier code division multiple access system in multipath fading channels." Ohio : Ohio University, 1998. http://www.ohiolink.edu/etd/view.cgi?ohiou1176401917.

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Rice, Michael, and Eugene Law. "AERONAUTICAL TELEMETRY FADING SOURCES AT TEST RANGES." International Foundation for Telemetering, 1997. http://hdl.handle.net/10150/609809.

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International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada
This paper describes the two main causes of fading encountered at test ranges. The first cause of fading results from nulls in the transmit antenna gain pattern. Variations in the received signal level are a result of changes in the gain pattern as the spatial relationship between transmitter and receiver change. The second cause of fading is due to multipath interference. This occurs when multiple copies of the transmitted signal with different delays arrive at the receiver and are phased relative to each other so that destructive interference occurs.

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Conder, Phillip. "Using multipath fading to increase performance of wireless communication systems." Access electronically, 2005. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20061005.155049/index.html.

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Katz, Ettie. "Trellis codes for multipath fading ISI channels with sequential detection." Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/13908.

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19

CASTELLANOS, PEDRO VLADIMIR GONZALEZ. "MODELING ATMOSPHERIC MULTIPATH FADING IN LINE-OF-SIGHT MICROWAVE LINKS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2003. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=4106@1.

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Os desvanecimentos por multipercurso atmosférico são a principal causa de degradação do desempenho de enlaces rádio digitais de alta capacidade, acentuando os efeitos do ruído térmico e da interferência intersimbólica na taxa de bits errados. A previsão da distribuição cumulativa de probabilidades destes desvanecimentos em função de parâmetros do enlace e características rádio climáticas da região é de fundamental importância no projeto de sistemas rádio digitais terrestres. Existem na literatura técnica métodos para previsão do desvanecimento em enlaces individuais, mas não para um tronco de microondas formado por vários enlaces. Medidas realizadas no Brasil indicam que a usual suposição de decorrelação total entre desvanecimentos profundos em enlaces consecutivos em um mesmo tronco é pessimista, podendo levar a uma indisponibilidade combinada maior do que a real. Neste trabalho foram analisados dados experimentais de 15 enlaces na região centro-oeste do Brasil e 5 enlaces no Japão e desenvolvido um modelo empírico de previsão da distribuição conjunta do desvanecimento por multipercurso atmosférico conjunta em enlaces adjacentes. O modelo apresenta boa concordância com os resultados experimentais e fornece uma nova expressão para o cálculo da indisponibilidade em troncos de microondas formados por vários enlaces. Os dados experimentais foram utilizados ainda para modelar a duração de eventos de atenuação por multipercurso em enlaces em visibilidade. Mostrou-se que a distribuição de duração de eventos é bem caracterizada por distribuições de Weibull. Esta caracterização permite a distinção entre eventos de perda de qualidade (duração inferior a 10 segundos) e de indisponibilidade (duração superior a 10 segundos).
Multipath fading is the main cause of performance degradation in high capacity line-of-sight microwave links, increasing enhancing the effects of the thermal noise and intersymbol interference in the bit error rate. Tested methods are available in the literature for the prediction of cumulative probability distribution multipath fading in individual link but not in a microwave network formed by several tandem links. Measurements carried out in Brazil indicate that the usual assumption that deep fade events in consecutive links are totally uncorrelated may be pessimistic for tropical regions and may lead to the prediction excessive multihop links unavailability. Experimental data obtained in measurements of multipath fading in 15 pairs of tandem links located in the center- western region of Brazil were analyzed to provide cumulative distributions of attenuation in each pair. Similar results are available in the literature for 5 pairs of links in Japan. Based on these results, an empirical model was developed for the prediction of the joint probability distribution the multipath fading in adjacent links was developed. The attenuation simultaneously exceeded in both links for given percentage of time can be predicted as a function of the equiprobable values of attenuation exceeded in the individual links, path lengths and operation frequency. The predicted distributions show good agreement with the experimental results and provide an expression for the calculation of unavailability of line-of- sight tandem links. The experimental data had been used still to model the duration of events of attenuation for multipath of links in visibility. One revealed that the distribution of duration of events well is characterized by distributions of Weibull. This characterization allows the distinction between events of loss of quality (lowest duration at 10 seconds) and of non-availability (higher duration the 10 seconds).

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COSTA, FRANCISCO ANTONIO TARDIN. "ERFORMANCE OF DIGITAL RADIO SYSTEMS IN VIEW OF MULTIPATH FADING." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1986. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=9474@1.

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É desenvolvido um modelo para sistemas rádio-digitais que inclui os tipos de modulação mais usuais como PSK-4, PSK- 8, QAM-16, com recepção coerente. Neste modelo é considerado um canal linear e um meio de propagação sujeito a desvanecimento por multipercursos, sendo analisadas algumas alternativas para sua representação, em particular os chamados modelos de dois e três raios. Neste contexto é considerado o problema do cálculo de desempenho, especialmente o cálculo da confiabilidade dos sistemas. Utilizando-se um critério de probabilidade de erro, calculada numericamente pelo método da Quadratura de Gauss, ou um critério de fechamento de olho, são implementados algoritmos para cálculo de Assinaturas dos diversos sistemas. A partir destas assinaturas os sistemas são comparados, analisando-se os efeitos da margem do enlace e da largura de faixa. Alguns métodos de cálculo de confiabilidade são analisados e aplicados ao estudo comparativo dos sistemas.
It´s developed a model for digital-radio systems which includes the most usual ones as PSK-4, PSK-8, QAM-16, with coherent detection. This model considers a linear channel and a propagation medium subject to multipath fadings, being analyzed some of it´s possible representations, particularly the so called two paths and three paths models. It is specially considered the computation of the systems´ outage probability. Using an error probability criterium numerically computed by the Gauss Quadrature Rule or an eye-closure one, algorithms are implemented to calculate Systems´ Signatures. Based on these signatures systems are compared considering their bandwidths and link´s flat fading margin. Some methods for outage probability calculation are analyzed and applied to systems´ comparations.

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Lun, Desmond S. (Desmond Siu Men) 1979. "Error exponents for multipath fading channels : a strong coding theorem." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/16891.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.
Includes bibliographical references (leaves 43-45).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
We derive upper and lower bounds on the probability of error (the exponents of which are the error exponents) with "peaky" signaling -- the signaling strategy that achieves the capacity of the multipath fading channel under an average power constraint in the limit of infinite bandwidth. These bounds constitute a strong coding theorem for the channel as they not only delimit the range of achievable rates, but also give us a relationship among the error probability, data rate, bandwidth, "peakiness", and fading parameters such as the coherence time. They can be used to compare peaky signaling to other large bandwidth systems over fading channels, such as ultrawide band (UWB) radio and wideband CDMA. We first derive an upper bound for general fading, then specialize to the case of Rayleigh fading where we obtain upper and lower bounds that are exponentially tight and therefore yield the reliability function. We study the behavior of the reliability function and the upper and lower error probability bounds numerically.
by Desmond S. Lun.
S.M.

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Welling, Kenneth. "Coded Orthogonal Frequency Division Multiplexing for the Multipath Fading Channel." International Foundation for Telemetering, 1999. http://hdl.handle.net/10150/608525.

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International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada
This paper presents a mathematical model for Coded Orthogonal Frequency Division Multiplexing (COFDM) in frequency selective multipath encountered in aeronautical telemetry. The use of the fast Fourier transform (FFT) for modulation and demodulation is reviewed. Error control coding with interleaving in frequency is able to provide reliable data communications during frequency selective multipath fade events. Simulations demonstrate QPSK mapped COFDM performs well in a multipath fading environment with parameters typically encountered in aeronautical telemetry.

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Law, Eugene L. "PERFORMANCE OF PCM/FM DURING FREQUENCY SELECTIVE FADING." International Foundation for Telemetering, 1995. http://hdl.handle.net/10150/608409.

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International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, Nevada
This paper will discuss the performance of pulse code modulation (PCM)/frequency modulation (FM) during frequency selective fading. Frequency selective fading occurs when the attenuation in part of the frequency band of interest is much greater than in the rest of the band of interest. The frequency selective fading model used in this paper assumes that two paths with different delays exist between the transmitter and receiver (multipath). The two-path model was simulated in the laboratory and the effects of frequency selective fading on the radio frequency (RF) spectrum and on the waveforms at the output of the FM demodulator were measured. A mathematical model was also used to predict the effects of frequency selective fading. The predicted waveshapes are compared with the laboratory data. A simple demodulator which alleviates the effects of frequency selective fading on PCM/FM at moderate signal-to-noise ratios (SNRs) will be described. This demodulator is created by detuning the telemetry receiver by a frequency equal to approximately one-half of the intermediate frequency (IF) bandwidth and using the receiver’s amplitude modulation (AM) detector output rather than the FM detector output. The performance of this offset AM demodulator will be compared with the performance of an FM demodulator. Frequency selective fades measured in real-world environments will be also presented.

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Dye, Ricky G., and Lyman D. Horne. "PARAMETER CHARACTERIZATION ON A TELEMETRY CHANNEL INCLUDING THE EFFECTS OF THE SPECULAR RAY." International Foundation for Telemetering, 1995. http://hdl.handle.net/10150/608412.

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International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, Nevada
The aeronautical channel model is a good candidate for modeling the effects of multipath interference of telemetry signals on test ranges. The aeronautical fading channel model is parameterized by the signal to noise ratio, the Doppler shift and time delay between the specular and direct components, the specular to direct power ratio, the direct to diffuse power ratio, and the bandwidth of the multipath fading process. Segments of weighting signal data measured during a test at Tyndall AFB provide data which can be used to determine typical values of the above parameters in a variety of telemetering environments. In this paper, the set of parameters which most closely model the actual telemetry channel using the Tyndall data is determined.

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Povey, Gordon J. R. "Spread spectrum receiver architectures for mobile channels subject to multipath fading." Thesis, University of Edinburgh, 1992. http://hdl.handle.net/1842/12133.

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Recently there has been considerable interest in spread spectrum techniques for use in commercial communication systems. One particular area where there may be considerable benefit is in mobile radio systems. Many of the difficulties presented by mobile radio communications result from the multipath fading which is present on the channel. This can lead to large reductions in the available channel capacity if measures are not taken to combat its effects. The use of diversity is highly effective in ameliorating the effects of fading. This research is concerned with an anti-multipath receiver architecture, the RAKE receiver, which uses the inherent multipath diversity of the received spread spectrum signal. As a precursor to this work we describe a spread spectrum correlator architecture, the serial-parallel receiver, which is capable of resolving the multipath diversity signals which are subsequently used in the RAKE receiver. A digital serial-parallel correlator is developed which has negligible implementation loss, fast PN code synchronisation, and can provide very large processing gains. The performance obtained from this spread spectrum receiver architecture is demonstrated using a DSP based implementation, and is shown to improve upon previous analogue implementations in most respects. It is particularly attractive for mobile communications since it can resolve the multipath signal components without the need for a large time-bandwidth product matched filter, or multiple active correlators. The performance of an adaptive RAKE receiver, using simple alpha tracker profile estimation filters, is analysed for a simulated UFG mobile channel (vehicular and hand-held) for a typical urban environment. Bit error rate graphs indicate that the performance approaches the theoretical upper bound when the signal fading is slow relative to the bit rate of the system (e.g. hand-held operation).

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Kelly, Joseph Michael. "Fading multipath bias errors in global positioning system receiver tracking loops." Ohio University / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1173973833.

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Zhao, Qiang. "New Results on Selection Diversity over Fading Channels." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/31363.

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This thesis develops a mathematical framework for analyzing the average bit error rate performance of five different selection diversity combining schemes over slow, frequency non-selective Rayleigh, Nakagami-m and Ricean fading channels. Aside from the classical selection diversity, generalized selection combining and the â maximum outputâ selection methods, two new selection rules based on choosing the branch providing the largest magnitude of log-likelihood ratio for binary phase shift keying signals (with and without phase compensation in the selection process) are also investigated. The proposed analytical framework is sufficiently general to study the effects of dissimilar fading parameter and unequal mean received signal strengths across the independent diversity paths. The effect of branch correlation on the performance of a dual-diversity system is also studied. The accuracies of our analytical expressions have been validated by extensive Monte-Carlo simulation runs. The proposed selection schemes based on the log-likelihood ratio are attractive in the design of low-complexity rake receivers for wideband CDMA and ultra wideband communication systems.
Master of Science

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Khan, Noor Muhammad Electrical Engineering &amp Telecommunications Faculty of Engineering UNSW. "Modeling and characterization of multipath fading channels in cellular mobile communication systems." Awarded by:University of New South Wales. School of Electrical Engineering and Telecommunications, 2006. http://handle.unsw.edu.au/1959.4/26999.

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Due to the enormous capacity and performance gains associated with the use of antenna arrays in wireless multi-input multi-output (MIMO) communication links, it is inevitable that these technologies will become an integral part of future systems. In order to assess the potential of such beam-oriented technologies, direct representation of the dispersion of multipath fading channel in angular and temporal domains is required. This representation can only be achieved with the use of spatial channel models. This thesis thus focuses on the issue of spatial channel modeling for cellular systems and on its use in the characteri- zation of multipath fading channels. The results of this thesis are presented mainly in five parts: a) modeling of scattering mechanisms, b) derivation of the closed-form expressions for the spatio-temporal characteristics, c) generalization of the quantitative measure of angular spread, d) investigation of the effect of mobile motion on the spatio-temporal characteris- tics, and e) characterization of fast fading channel and its use in the signature sequence adaptation for direct sequence code division multiple access (DS-CDMA) system. The thesis begins with an overview of the fundamentals of spatial channel modeling with regards to the specifics of cellular environments. Previous modeling approaches are dis- cussed intensively and a generalized spatial channel model, the 'Eccentro-Scattering Model' is proposed. Using this model, closed-form mathematical expressions for the distributions of angle and time of multipath arrival are derived. These theoretical results for the picocell, microcell and macrocell environments, when compared with previous models and available measurements, are found to be realistic and generic. In macrocell environment, the model incorporates the effect of distant scattering structures in addition to the local ones. Since the angular spread is a key factor of the second order statistics of fading processes in wireless communications, the thesis proposes a novel generalized method of quantifying the angular spread of the multipath power distribution. The proposed method provides almost all parameters about the angular spread, which can be further used for calculating more accurate spatial correlations and other statistics of multipath fading channels. The degree of accuracy in such correlation calculations can lead to the computation of exact separation distances among array elements required for maximizing capacity in MIMO systems or diversity antennas. The proposed method is also helpful in finding the exact standard deviation of the truncated angular distributions and angular data acquired in measurement campaigns. This thesis also indicates the significance of the effects of angular distribution truncation on the angular spread. Due to the importance of angular spread in the fading statistics, it is proposed as the goodness-of-fit measure in measurement campaigns. In this regard, comparisons of some notable azimuthal models with the measurement results are shown. The effect of mobile motion on the spatial and temporal characteristics of the channel is also discussed. Three mobile motion scenarios are presented, which can be considered to be responsible for the variations of the spatio-temporal statistical parameters of the multipath signals. Two different cases are also identified, when the terrain and clutter of the mobile surroundings have an additional effect on the temporal spread of the channel during mobile motion. The effect of increasing mobile-base separation on the angular and temporal spreads is elaborated in detail. The proposed theoretical results in spatial characteristics can be extended to characterizing and tracking transient behavior of Doppler spread in time-varying fast fading channels; likewise the proposed theoretical results in temporal characteristics can be utilized in designing efficient equalizers for combating inter-symbol interference (ISI) in time-varying frequency-selective fading channels. In the last part of the thesis, a linear state-space model is developed for signature sequence adaptation over time-varying fast fading channels in DS-CDMA systems. A decision directed adaptive algorithm, based on the proposed state-space model and Kalman filter, is presented. The algorithm outperforms the gradient-based algorithms in tracking the received distorted signature sequence over time-varying fast fading channels. Simulation results are presented which show that the performance of a linear adaptive receiver can be improved significantly with signature tracking on high Doppler spreads in DS-CDMA systems.

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Nebat, Yoav. "Wireless networks in non-ergodic multipath fading capacity and relaying performance analysis /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2007. http://wwwlib.umi.com/cr/ucsd/fullcit?p3258826.

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Thesis (Ph. D.)--University of California, San Diego, 2007.
Title from first page of PDF file (viewed June 8, 2007). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 111-115).

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Danilo, Florence A. "Detection techniques and performance analysis for fading multipath channels with unresolved components." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36800.

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Personal communication services (PCS) is one of the fastest growing sectors in telecommunications. PCS can be provided by wireless cellular communication systems, that operate in radio environments characterized as multipath fading channels. This thesis addresses the subject of signal detection and performance analysis over multipath Ricean/Rayleigh fading channels, when the multipath delays are known and the path resolvability assumption is not satisfied. The path resolvability condition asserts that the signal autocorrelation function vanishes ("strict") or it is small ("approximate") at inter-path delays. The strict path resolvability assumption is rarely satisfied, and even the approximate path resolvability condition is not always satisfied in practice. For example, the approximate path resolvability is not satisfied for narrow-band systems such as GSM, IS136, or their third generation derivatives and it is neither satisfied for wide-band systems, such as IS95 or W-CDMA, in indoors due to the relatively small multipath delays of these environments.
Existing demodulation schemes for multipath fading channels, such as Rake receivers, provide diversity gains but they are based on the path resolvability assumption. This thesis shows the severe limitations of the classical Rake receiver over unresolved multipath fading channels, and generalizes the Rake concept to improve performance. The optimal receiver that assumes knowledge of the specular component (specular coherent), and the optimal scheme that assumes knowledge of the specular component magnitudes only (non-coherent), are derived for unresolved Ricean multipath fading channels. It is shown that both include an orthogonalization (or decorrelation) stage that vanishes when the multipath is resolved. This thesis presents explicit forms of the Minimum Mean-Square Error estimator of the likelihood ratio estimator-correlator forms, and shows that the decorrelation operation is present in the estimation process. Based on the insight provided by these optimal schemes, suboptimal receivers more suitable for implementation are proposed.
Performance analysis results, for several binary modulation formats, demonstrate the importance of the decorrelation operation in yielding diversity gains and eliminating error floors under multipath unresolvability conditions. It is also shown that the knowledge of the specular component phase does not provide significant gains at high SNR for orthogonal FSK. Finally, it is shown that SNR gains can be obtained by exploiting the knowledge of the specular component magnitude.

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劉慶強 and Hing-keung Lau. "Pilot-symbol-aided techniques for spectrally efficient signals in multipath-fading channels." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1997. http://hub.hku.hk/bib/B31237198.

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de, Gaston David E. "BIT ERROR PERFORMANCE ANALYSIS OF BPSK IN THE PRESENCE OF MULTIPATH FADING." International Foundation for Telemetering, 2000. http://hdl.handle.net/10150/606793.

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International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California
The presence of multipath fading has been shown to degrade the performance of a wireless channel. This paper quantifies the effects of multipath interference on signal performance based on the estimated parameters of the multipath signal. Theoretical results are compared with actual results obtained through the Advanced Range Telemetry (ARTM) program.

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Lo, Norm W. K. (Norman Wai Keung) Carleton University Dissertation Engineering Systems and Computer. "Adaptive equalization for a multipath fading channel in the presence of interference." Ottawa, 1994.

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Lau, Hing-keung. "Pilot-symbol-aided techniques for spectrally efficient signals in multipath-fading channels /." Hong Kong : University of Hong Kong, 1997. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19669161.

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Ketcham, Richard. "Characterization and Mitigation of Hyper-Rayleigh Fading." ScholarWorks @ UVM, 2007. http://scholarworks.uvm.edu/graddis/121.

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Due to the unprecedented spatial and temporal resolution they offer, wireless sensor networks are considered an enabling technology for the distributed monitoring of industrial, military, and natural environments. As these systems migrate into vastly different and novel applications, new constraints are discovered that affect network reliability and utility. For example, wireless sensors are typically statically deployed and, unlike mobile systems, cannot move to a new location for better radio reception. As a result, the signal fades caused by non-optimal environmental conditions can increase the outage probability of the system, potentially rendering the network unreliable and ineffectual. Stochastic models that quantify link reliability and the effectiveness of diversity methods are often employed to understand the impact of such fading. However, the performance of these models applied to wireless sensor networks is entirely dependent on the appropriateness of the model with respect to the environment. This work first presents an empirical study of the propagation environment for a wingless, rotary aircraft, showing that the wireless environment within exhibits frequency-selective fading much more severe than predicted by current worst-case models (i.e., Rayleigh). An analysis is then given of the effectiveness of several diversity methods operating within such environments (referred to as hyper-Rayleigh). These fade mitigation techniques are simple enough to be employed for use with low-complexity wireless sensor hardware, and include spatial diversity, polar diversity, two-element passive combining, and two-element phased combining. Two-element phased combining is further developed by examining the effect that smaller element spacing has on diversity gain. A demonstration of a wireless

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Chadney, A. G. "Diversity techniques for leaky feeders." Thesis, University of Surrey, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375156.

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Paje, Vladimir I. "THE EFFECTS OF CARRIER FREQUENCY AND ANTENNA DIAMETER ON FREQUENCY SELECTIVE MULTIPATH FADING." International Foundation for Telemetering, 2000. http://hdl.handle.net/10150/606502.

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International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California
This paper uses ARTM channel sounding data collected at Edwards Air Force Base to investigate the dependency between the characteristics of frequency selective multipath fading and carrier frequency and ground based received antenna diameter. Channel model parameters are obtained from data sets measured at different frequencies and various ground based antenna diameters. The analysis shows that the multipath characteristics do not statistically change between the L-band and S-band carrier frequencies, but do change with antenna diameter. Furthermore, Flight 18 data shows that antenna diversity may be a useful technique to reduce data loss from multipath fading.

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Victory, Charles W. "Soft decision diversity coded DS/DPSK systems in pulse-jammed multipath-fading channels." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1999. http://handle.dtic.mil/100.2/ADA361319.

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Dissertation (Ph.D. in Electrical Engineering) Naval Postgraduate School, March 1999.
"March 1999". Dissertation supervisor(s): Charles W. Therrien, Tri T. Ha. Includes bibliographical references (p. 175-177). Also available online.

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Althaus, Frank. "A new low-cost approach to wireless communication over severe multipath fading channels /." Berlin : Logos-Verl, 2003. http://www.gbv.de/dms/ilmenau/toc/36641478X.PDF.

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Gao, Wei, Shih-Ho Wang, and Kamilo Feher. "BLIND EQUALIZATION FOR FQPSK AND FQAM SYSTEMS IN MULTIPATH FREQUENCY SELECTIVE FADING CHANNELS." International Foundation for Telemetering, 1999. http://hdl.handle.net/10150/607298.

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International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada
Blind adaptive equalization with application for Non-Linearly Amplified (NLA) quadrature amplitude modulation (QAM) systems in multipath selective fading channels is presented. With an offset sampling strategy in the receiver, the proposed blind equalization using Constant Modulus Algorithm (CMA) exhibits a fast convergent speed for a family of quadrature modulated systems in NLA and multipath fading channels. Feher’s patented Quadrature Phase Shift Keying (FQPSK) and Feher’s Quadrature Amplitude Modulation (FQAM) which correspond respectively to 4-state and 16-state QAM are used due to their higher Radio Frequency (RF) power and spectral efficiency in NLA channel. It has been shown that blind adaptive equalization can significantly open the eye signals in multipath frequency selective fading channels.

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Rice, Michael D., and Daniel H. Friend. "Reed-Solomon Coding as a Multipath Fading Countermeasure for PCM/FM Aeronautical Telemetry." International Foundation for Telemetering, 1998. http://hdl.handle.net/10150/609666.

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International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, California
This paper evaluates the use of Reed-Solomon error correcting codes as a countermeasure for the bursty errors caused by multipath fading seen in aeronautical telemetry channels. The tradeoff between code rate and interleaving depth is analyzed and an equation for predicting the code rate given a fixed burst length and interleaving depth is presented. Close agreement is found between predictions made by this equation and simulated results.

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Calatrava, Helena, and Mimmi Lindgren. "Simulation, Analysis and Detection of Indoor Multipath Fading Channels Using an SVM Classifier." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-297677.

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Nowadays, identification of fake data is an elaboratechallenge that calls for the use of machine learning techniques.This is due to the huge amount of data and its complexity makesthe differences indistinguishable even for the trained eye. In thisproject we use the MATLAB wlanTGnChannel System objectto simulate multipath fading channels that are comparable toreal impulse response measurements made by Ericsson AB of anindoor8×8MIMO (Multiple Input Multiple Output) system.We use an SVM classifier to compare the eigenvalues of theircorrelation covariance matrices, obtaining an accuracy of 84%.Comparing their power delay profiles (PDPs) happens to bea classification task of low complexity due to time resolutionlimitation in the real measurements. We suggest that the proposedMATLAB model strongly differs from the real data we have beenprovided with.
Nu för tiden så är identifiering av fejkad data en svår utmaning som ofta kräver maskininlärningstekniker. Detta beror på den stora mängden data och att komplexiteten i datat gör att skillnaderna kan vara svår att se även för ett tränat öga. I det här projektet använder vi oss av MATLABs systemobjekt wlanTGnChannel för att simulera flervägs fädningskanaler som kan jämföras med riktiga impulssvarsmätningar gjorda av Ericsson AB av ett innomhus 8 X 8 MIMO(Multiple Input Multiple Output) system. Vi använde en SVM (stödvektormaskins) klassificerare för att jämföra egenvärdena av deras korrelationskovariansmatriser, vilket erhåller en noggranhet på 84%. Att jämföra deras power delay profiles (PDP) råkar vara ett klassificeringsproblem av låg svårighetsgrad på grund av tidsupplösningsbegränsningar för de riktiga mätningarna. Vi vill påstå att den tilltänkta MATLAB- modellen aviker mycket från den givna datan.
Kandidatexjobb i elektroteknik 2020, KTH, Stockholm

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"Residual noise after stripping on fading multipath channels." Massachusetts Institute of Technology, Laboratory for Information and Decision Systems], 1994. http://hdl.handle.net/1721.1/3376.

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Huang, Yih-Jinn, and 黃益進. "Adaptive Estimation and Equalization of Multipath Fading Channels." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/99524864001182776734.

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博士
國立清華大學
電機工程學系
91
This dissertation proposes two channel-estimation based adaptive decision feedback equalizers (DFEs) to treat the estimation and equalization problems for multipath fading channels. The tap coefficients of such a fading channel are modeled as complex Gaussian stochastic processes. In the proposed design methods, the design procedure is divided into two steps. First, Kalman filtering algorithm which can achieve minimum variance estimator is developed to track the time-varying tap coefficients. Then based on the estimated tap coefficients and error covariance, two adaptive DFEs, which are constructed to minimize the mean square error (MSE) function in the frequency and time domain respectively, are designed to reconstruct the transmitted sequence. Since the information of channel dynamics (the state space equation of channel model) is employed to track the time-varying tap coefficients, the proposed adaptive DFEs exhibit a better reconstruction performance than the conventional adaptive equalizer. To demonstrate the superior performance of the proposed adaptive DFEs, some illustrative simulations are presented. Furthermore, performance analysis about minimum mean square error (MMSE) achieved by the proposed design methods is also discussed in this study.

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Lin, Yue Hsiang, and 林裕翔. "A Receiver with Oversampling for Multipath Fading Channels." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/80828242661517091311.

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碩士
國立清華大學
電機工程研究所
82
A signal transmitted through a multipath fading channel will be distroied by the nonideal effects of the channels. It is difficult for the receiver to detect the received signals correctly. In this thesis, we will introduce a reconstructive over- sampling receiver structure consist of a preproce- ssor, a estimator, a postprocessor and a detector. In this reconstructive receiver structure, the pr- eprocessor will extract the sufficient statistics of the channels and the estimator will use these sufficient ststistics to estimate the fading gains of the channel. The postprocessor will reconstruct or compensate the received signal by the estimated channel gains and the detector can detect the sig- nal infomations by the reconstructive signals. In this receiver structure we try to implement the o- versampling techinques in the preprocessor. After applying oversampling on the preprocessor, The re- ceiver will extract more sufficient statistics fr- om the fading chennls. If the oversampling rate is fast enough the resolution of the delay paths of the multipath fading channel caused by multipath effect will increase. In the other word, it is an- other wind-band technique implementation. In this thesis, we will introduce some early works about the receivers for multipath fading channels in ch- apter 1. In chapter 2, we will introduce the char- acteristics of the multipath fading channels. In chapter 3, the influences for implementing oversa- mpling techniques in the receiver will be discuss- ed. In chapter 4, we will design a practical over- sampling receiver structure. We will derive a bit error probability upper bound by doing the perfor- mance analysis of that practical receiver. in cha- pter 5 and design a program simulator of the prac- tical receiver and show some simulation results. We give a conclusion about this oversampling rece- iver in chapter 7.

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Chi-chang, Chen, and 陳啟昌. "On Adaptive Sequence Estimation for Multipath Fading Channels." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/66014130636492871095.

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Jan, Da-Shang, and 簡大翔. "Performance of Turbo Codes in Multipath Fading Channels." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/17613315689352163385.

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碩士
國立交通大學
電信研究所
85
AbstractA class of powerful error-correcting codes called parallel concatenated codes, or turbo codes, has been proposed recently. Such a code consists of two or more parallel recursive systematic convolutional codes, each "subcode" is used to encode the same but independently interleaved data sequence. Together with a maximum a posteriori probability (MAP) iterative decoding rule, turbo codes have been shown to achieve bit error rate performance close to the Shannon's AWGN limit. The performance and behavior of turbo codes in practical multipath fading channels, however, remains to be determined. The fading effect usually incurs burst errors that greatly hinder a channel code's error correcting capability. Modification of the decoder structure is needed to account for the influence of multipath fading. The purpose of this thesis is to investigate the impacts of channel conditions and various system design alternatives on the overall system performance. Channel models used are: independent and correlated Rayleigh fading channels and those based on Jakes' model. Given the channel model we then study how the channel state information is derived and such information can be used to help decoding. Computer simulation is employed to quantify various system behavior and to provide numerical examples that give us system solutions.

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魏鴻富. "Adaptive equalizer for fast time-varying multipath fading channels." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/22885189023963158769.

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Chung, Nai-Chi, and 鍾乃騏. "Performance Analysis of OMM Families in Multipath Fading Channels." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/49857021417749744162.

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碩士
國立臺灣大學
電信工程學研究所
95
The orthogonally multiplexed modulation (OMM) families are studied for the multipath fading channels. The OMM families include four different modulation schemes—OMOAM, OMOPM, OMO2AM, and OMO2PM, which provide a multitude of new multidimensional modulations by setting appropriate parameters and basis sets. Orthogonal frequency division multiplexing (OFDM) is one of the specific examples. In this thesis, by different basis assignments, the OMM signals are mapped to the OFDM signals to suit for fast Fourier transform implementation. Because of various applications of the multidimensional modulations in practical wireless communications, we analysis the error performance of OMM signals in multipath fading channels. Based on the maximum-likelihood decision rule, the upper bounds and approximated upper bounds of the bit error probability are analyzed and verified by the simulation. Finally, the error performance and the spectral efficiency of the OMM families with two types of basis assignments are discussed in terms of different multipath fading channels, and some specific modulation formats are shown to provide good choices of power and spectral efficiencies.

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Wang, Shung-Yuan, and 王聲遠. "Simplified Sequence Detection on Frequency-selective Multipath Fading Channels." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/31373691897578889548.

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Dissertations / Theses on the topic 'Multipath fading'

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