Dissertations / Theses: 'Multipath channels'

1

Ruprecht, Jürg. "Maximum likelihood estimation of multipath channels /." [S.l.] : [s.n.], 1989. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=8789.

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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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Landron, Orlando. "Microwave multipath resolution in microcellular channels." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-03032009-040639/.

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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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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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6

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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7

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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8

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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Cameron, Rick. "Performance analysis of CDMA systems in multipath channels." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-10312009-020344/.

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Boayue, Abraham. "Characterization of Underwater Acoustic Communication Channels : Statistical Characteristics of the Underwater Multipath Channnels." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for telematikk, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-23108.

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Underwater communication and networking have become very essential both for commer-cial and military purposes. The number of research conducted in this field has increased over the past few decades. The need to communicate between sensor nodes in sensor network requires the characterization of underwater acoustic channel. This project focuses on the statistical characterization of an underwater communication channel using real data. This kind of approach of characterizing a channel makes it possible to access the performance of modern digital systems before they are built. The main idea behind this thesis report is to be able to perform simulations on real data using matlab to get reasonable results that can be compared to existing research papers.

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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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Dmochowski, Pawel Adam. "Frequency domain equalization for high data rate multipath channels." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ59375.pdf.

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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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Çelebi, Hasan Basri. "Noise and Multipath Characteristics of Power Line Communication Channels." Scholar Commons, 2010. https://scholarcommons.usf.edu/etd/1594.

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With the recent developments in technology, information and communication technologies (ICTs) are becoming more widespread and one of the basic building blocks of every humans life. The increasing demand in broadband communication calls for new technologies. Power line communication (PLC) is one of the potential candidates for next generation ICTs. Although communication through power lines has been investigated for a long time, PLC systems were never taken into account seriously because of its harsh communication medium. However, with the development of more robust data transmission schemes, communication over the power lines is becoming a strong alternative technology because of the existence of the infrastructure and the ubiquity of the network. In order to establish reliable communication systems operating on power line networks (PLNs), characteristics of power line channels have to be investigated very carefully. Unpredictable characteristics of PLNs seriously affect the performance of communication systems. Similar to the other communication channels, PLC environment is affected by noise, attenuation, and multipath type of channel distortions. The level of noise in PLNs is much higher than any other type of communication networks. Furthermore, the frequency dependent attenuation characteristics of power lines and multipath stemming from impedance mismatches are the other distortion factors which have to be investigated in order to establish a reliable PLC system. In this thesis, we focus on modeling of noise, frequency dependent attenuation, and multipath characteristics of power line channels within the frequency range between 30kHz and 30MHz.

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Rice, Michael, Gaston David de, Adam Davis, Gus German, and Christian Bettwieser. "ARTM CHANNEL SOUNDING RESULTS – AN INVESTIGATION OF FREQUENCY SELECTIVE FADING ON AERONAUTICAL TELEMETRY CHANNELS." International Foundation for Telemetering, 1999. http://hdl.handle.net/10150/608746.

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International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada
Initial results of wideband channel sounding experiments sponsored by the Advanced Range Telemetry (ARTM) program are presented. Data collected at Edwards EAFB during the Winter 1998-1999, are analyzed in the frequency domain to estimate the number, strength, and delays of the significant multipath reflections observed during the experiments. We observe that the channel is adequately modeled using two or three multipath reflections. The multipath fade events are correlated with recorded bit error rates and transmitter location to provide a comprehensive overview of the channel characteristics. Summaries from two test flights are included where it is seen that the 2- and 3-ray channel models provide excellent models for the data. In general, the 3-ray model captures the essential features of the multipath interference. In this model the first multipath is a strong specular reflection with relative amplitude greater than 0.5 and relative delay in the 30 to 70 ns range. The second multipath is a much weaker reflection with relative amplitude less than 0.5 and relative delay in the 175 to 325 ns range.

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Kafaru, Olutumininu Olufolabomi. "An environment-dependent approach to wideband modelling and computer simulation of UHF mobile radio propagation in built-up areas." Thesis, University of Liverpool, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.253411.

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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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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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Kannappa, Sandeep Mavuduru. "Reduced Complexity Viterbi Decoders for SOQPSK Signals over Multipath Channels." International Foundation for Telemetering, 2010. http://hdl.handle.net/10150/604300.

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ITC/USA 2010 Conference Proceedings / The Forty-Sixth Annual International Telemetering Conference and Technical Exhibition / October 25-28, 2010 / Town and Country Resort & Convention Center, San Diego, California
High data rate communication between airborne vehicles and ground stations over the bandwidth constrained Aeronautical Telemetry channel is attributed to the development of bandwidth efficient Advanced Range Telemetry (ARTM) waveforms. This communication takes place over a multipath channel consisting of two components - a line of sight and one or more ground reflected paths which result in frequency selective fading. We concentrate on the ARTM SOQPSKTG transmit waveform suite and decode information bits using the reduced complexity Viterbi algorithm. Two different methodologies are proposed to implement reduced complexity Viterbi decoders in multipath channels. The first method jointly equalizes the channel and decodes the information bits using the reduced complexity Viterbi algorithm while the second method utilizes the minimum mean square error equalizer prior to applying the Viterbi decoder. An extensive numerical study is performed in comparing the performance of the above methodologies. We also demonstrate the performance gain offered by our reduced complexity Viterbi decoders over the existing linear receiver. In the numerical study, both perfect and estimated channel state information are considered.

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Harada, Koji. "Studies on Parameter Estimation of Multipath Channels without Utilizing Pilot Signals." 京都大学 (Kyoto University), 2012. http://hdl.handle.net/2433/157484.

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21

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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22

Lau, W. H. "Investigation of techniques for modelling telecommunication channels subject to multipath phenomena." Thesis, University of Portsmouth, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235295.

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23

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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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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Cowl, David J. "Performance of code division multiple access on multipath channels - an exact analysis." Thesis, University of Canterbury. Electrical and Electronic Engineering, 1994. http://hdl.handle.net/10092/5449.

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This thesis presents an exact analysis approach to the investigation of the average probability of error performance for a code division multiple access (CDMA) system operating over multipath fading channels. The system in question has K users transmitting direct sequence spread spectrum signals over the same bandwidth. The receiver employs a selection diversity algorithm to select the path with the strongest desired signal at any given time. Performance results are presented for three classes of channel model, those being the single path non-fading channel, the single path fading channel and the multiple path fading channel. The performance is also presented for a system where ideal power control is applied. The channel model for the single path fading channel is a single path whose gain has a Rayleigh distribution. The channel model for the multiple path fading channel is a tapped delay line model, where each tap is equally spaced in time, and has a gain with a Rayleigh distribution. The average gain for each tap is specified by an average delay profile. The exact analysis approach involves finding the probability density functions (pdf's) for the per-user multi-user interference and the inter-symbol interference from the desired user. These probability density functions are derived from the pdf's of each contributing factor to the interference, including the empirical cross-correlation function pdf. The characteristic functions of the per-user multi-user interference and the inter-symbol interference are found from the pdf's, and the characteristic function of the total interference is given by the product of the inter-symbol interference characteristic function and the K - 1 multi-user interference characteristic functions. The average probability of error is calculated using the characteristic function of the total interference. Conclusions on the performance of the selection diversity algorithm and the power control algorithm are drawn, based on the results.

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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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Lim, Hong Meng. "On the average capacity of MIMO channels in outdoor multipath urban environments." Thesis, University of Birmingham, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420409.

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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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Abd, El-Sallam Amar. "Low order channel estimation for CDMA systems." Thesis, Curtin University, 2005. http://hdl.handle.net/20.500.11937/2420.

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New approaches and algorithms are developed for the identification and estimation of low order models that represent multipath channel effects in Code Division Multiple Access (CDMA) communication systems. Based on these parsimonious channel models, low complexity receivers such as RAKE receivers are considered to exploit these propagation effects and enhance the system performance. We consider the scenario where multipath is frequency selective slowly fading and where the channel components including delays and attenuation coefficients are assumed to be constant over one or few signalling intervals. We model the channel as a long FIR-like filter (or a tapped delay line filter) with the number of taps related to the ratio between the channel delay-spread and the chip duration. Due to the high data rate of new CDMA systems, the channel length in terms of the chip duration will be very large. With classical channel estimation techniques this will result in poor estimates of many of the channel parameters where most of them are zero leading to a reduction in the system performance. Unlike classical techniques which estimate directly the channel response given the number of taps or given an estimate of the channel length, the proposed techniques in this work will firstly identify the significant multipath parameters using model selection techniques, then estimate these identified parameters. Statistical tests are proposed to determine whether or not each individual parameter is significant. A low complexity RAKE receiver is then considered based on estimates of these identified parameters only. The level of significance with which we will make this assertion will be controlled based on statistical tests such as multiple hypothesis tests. Frequency and time domain based approaches and model selection techniques are proposed to achieve the above proposed objectives.The frequency domain approach for parsimonious channel estimation results in an efficient implementation of RAKE receivers in DS-CDMA systems. In this approach, we consider a training based strategy and estimate the channel delays and attenuation using the averaged periodogram and modified time delay estimation techniques. We then use model selection techniques such as the sphericity test and multiple hypotheses tests based on F-Statistics to identify the model order and select the significant channel paths. Simulations show that for a pre-defined level of significance, the proposed technique correctly identifies the significant channel parameters and the parsimonious RAKE receiver shows improved statistical as well as computational performance over classical methods. The time domain approach is based on the Bootstrap which is appropriate for the case when the distribution of the test statistics required by the multiple hypothesis tests is unknown. In this approach we also use short training data and model the channel response as an FIR filter with unknown length. Model parameters are then estimated using low complexity algorithms in the time domain. Based on these estimates, bootstrap based multiple hypotheses tests are applied to identify the non-zero coefficients of the FIR filter. Simulation results demonstrate the power of this technique for RAKE receivers in unknown noise environments. Finally we propose adaptive blind channel estimation algorithms for CDMA systems. Using only the spreading code of the user of interest and the received data sequence, four different adaptive blind estimation algorithms are proposed to estimate the impulse response of frequency selective and frequency non-selective fading channels. Also the idea is based on minimum variance receiver techniques. Tracking of a frequency selective varying fading channel is also considered.A blind based hierarchical MDL model selection method is also proposed to select non-zero parameters of the channel response. Simulation results show that the proposed algorithms perform better than previously proposed algorithms. They have lower complexity and have a faster convergence rate. The proposed algorithms can also be applied to the design of adaptive blind channel estimation based RAKE receivers.

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Zeydan, Engin. "Channel Phase And Data Estimation In Slowly Fading Frequency Nonselective Channels." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607419/index.pdf.

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In coherent receivers, the effect of the multipath fading channel on the transmitted signal must be estimated to recover the transmitted data. In this thesis, the channel phase and data estimation problems are investigated in a transmitted data sequence when the channel is modeled as slowly fading, frequency non-selective channel. Channel phase estimation in a transmitted data sequence is investigated and data estimation is obtained in a symbol-by-symbol MAP receiver that is designed for minimum symbol error probability criterion. The channel phase is quantized in an interval of interest, the trellis diagram is constructed and Viterbi decoding algorithm is applied that uses the phase transition and observation models for channel phase estimation. The optimum coherent and noncoherent detectors for binary orthogonal and PSK signals are derived and the modulated signals in a sequence are detected in symbol-by-symbol MAP receivers.Simulation results have shown that the performance of the receiver with phase estimation is between the performance of the optimum coherent and noncoherent receiver.

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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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34

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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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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36

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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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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38

Zhao, Guangze. "Impact of multipath clustering on correlation and MIMO system performance in Rayleigh fading channels." Thesis, University of Ottawa (Canada), 2003. http://hdl.handle.net/10393/26552.

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This thesis extends single cluster of multipath channel model to multi-cluster one. This multi-cluster channel model, which is more accurate than single cluster, has a profound effect on MIMO channel correlation and system performances. Based on this multi-cluster channel model, closed-form expressions of channel correlation are derived. The results using multi-cluster channel model agree with those using single cluster one. The results of the derived equations are also in full agreement with the results obtained from Monte-Carlo simulations. Using two-cluster channel model, the MIMO channel correlation coefficient has an oscillatory behavior with respect to the antenna spacing. Besides the angular spread and mean angle of arrival of the 2nd cluster, the power allocation has a significant effect on MIMO channel correlation. Similar to the behavior of channel correlation, both the MIMO channel capacity and diversity gain also oscillates with respect to the antenna spacing because of the 2nd cluster. It is also demonstrated that it is possible to orient the antenna array in such a way that the correlation is minimized and the maximum capacity can be achieved provided that the minimum element spacing is respected.

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Zeng, Zong-Yang, and 曾宗揚. "Blind Adaptive Channel Shortening and Frequency Domain Equalizations in Multipath Fading Channels." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/47267017287840433475.

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碩士
國立中興大學
電機工程學系所
99
Cyclic prefix (CP) is widely used to communication systems, because it is useful and robust to cancel Inter-symbol interference (ISI). CP this technique it not only can cancel ISI, but also to reduce the channel with the Channel-Shortening Equalizer (CSE). This technique CSE is using this way that the length of channel is equal with the length of CP the last CP subtract the last symbol will be zero. Follow this way if other CPs with other copy symbols subtraction also zero or minimum to zero, the channel is equal to one tap channel for the transmission data. Using this way demodulate the transmission data, we can use the sample (one tap) frequency-domain equalization to restore it. And orthogonal frequency-division multiplexing (OFDM) and Code Division Multiple Access (CDMA) is a popular transmission format for emerging wireless communication systems, including satellite radio, various wireless local area network (LAN) standards, and digital broadcast television. So in this paper we also use the CSE in the DS-CDMA and the OFDM-CDMA system.

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Chang, Hao-hsun, and 張顥薰. "Pilot-Based Channel Estimation Methods for Wireless Relay Networks in Multipath Channels." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/06265408668929249952.

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碩士
國立中央大學
通訊工程學系
101
Recently, wireless communication technology and media application service grows faster than ever, providers and users all expect higher transmission rate and better Quality of Service (QoS). Because the conventional point-to-point communication is susceptible to channel fading, shadowing effect, and multipath channel effect, communication quality at cell edge or severe shadowing environments is low. Relay networks have been emerged as a promising technology to improve the link quality in severe channel fading and shadowing environments or increase the cell coverage by spatial diversity gain. In most of the existing literature, it is assumed that the perfect channel state information (CSI) of each link are available at the destination. However, the successful implementation of the relay networks relies on the accurate CSIs of each link. In this thesis, we propose time-domain channel estimators for relay networks in multipath channels. Based on the maximum likelihood (ML) and minimum mean square error (MMSE) criteria, two kinds of channel estimation methods, integrated and disintegrated, are investigated for estimating relay-to-destination (RD), source-to-relay (SR), or their cascaded channel links. A denoise-and-forward (DF) estimator is proposed to further improve the performance by imposing a denoising matrix to effectively suppress the noise enhancement effect at the relay node. Computer simulation is used to demonstrate the effectiveness of the proposed time-domain channel estimation methods.

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41

"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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42

Yen, Chien-Yi, and 顏健益. "Adaptive CDMA Multiuser Detection in Asynchronous Multipath Channels." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/58265375825446190839.

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碩士
國立中山大學
通訊工程研究所
92
The analysis of this thesis concerns various problems associated with adaptive CDMA multi-user detection in asynchronous multi-path channels. Starting with some simple concept of Wiener filtering and correlating detector, we construct a novel adaptive decorrelating transversal filter suitable for CDMA multi-user detection in uplink channels. Then, we make use of the LMS and RLS algorithms to replace the traditional decorrelating transversal filter (which is also called inverse matrix based decorrelating detector) to make the scheme work fully adaptively. In this way, a great advantage in terms of computation load reduction is made possible. To further improve the detection efficiency, we will also make use of RAKE receiver to enhance the overall decision reliability in the proposed adaptive CDMA MUD scheme. Although the focus of this thesis is put on analysis, we will also use computer simulations to counter-check the results obtained from theoretical analysis, showing a very good match between the two. In the last part of the thesis, we will also discuss the various issues on fully blind implementation of the proposed adaptive CDMA MUD scheme with some useful multipath channel delay and amplitude estimation algorithms.

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43

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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44

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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45

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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46

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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47

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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Huang, Jen-Sheng, and 黃振盛. "Adaptive Modulation Schemes for 3G WCDMA in Multipath Channels." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/59628826379583389854.

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碩士
國立雲林科技大學
電機工程系碩士班
92
People’s desire of seeking information and entertainments are unlimited. One day, when all mobile phones can connect to the Internet anytime wirelessly by broadband, the world we see will consist of services and information at hand, connecting tightly with our live. Therefore, WCDMA system is developed to deal with the contingency. After the WCDMA system has developed, many people got involved into its research in order to solve the incompatibility between its mantle and capacity efficiently, eliminate the interference, increase the system capacity, and satisfy the needs of its user. Thus, a lot of technologies are being created in its follow-up development. In order to increase the transmission throughput of the downlink system in WCDMA system, we bring up adaptive modulation schemes. In standard 3GPP R99, the modulation scheme use QPSK for transmission. Here, we add the 16QAM, 64QAM, and the original QPSK modulation schemes to select the modulation form according to the condition of the transmission channel, and also consider to transmit in multipath channels. We utilize Matlab Simulink for the simulation experiment, and then bring up the conclusion by the data comes out from the experiment.

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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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50

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 channels'

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