Dissertations / Theses: 'Fading'

1

Hernandez, Jose H. "Digital communications over non-fading and fading channels." Thesis, Monterey, Calif. : Naval Postgraduate School, 2008. http://edocs.nps.edu/npspubs/scholarly/theses/2008/Sept/08Sep%5FHernandez.pdf.

Full text

Abstract:

Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, September 2008.
Thesis Advisor(s): Robertson, Clark R. "September 2008." Description based on title screen as viewed on November 5, 2008. Includes bibliographical references (p. 75). Also available in print.

APA, Harvard, Vancouver, ISO, and other styles

2

Middleton, Neil 1977. "Fading points." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=81476.

Full text

Abstract:

Fading Points is a piece of music for large wind ensemble. The work is concerned with time perception and is designed to convey to the listener a long temporal progression from slow music to fast music. To this end, the work is written using musical gestures specifically designed for their portrayal of musical time. The work consists of four sections, each of which is described in detail in the analytical part of the thesis. The analysis also describes the rhythmic language, which is created around short rhythmic cells. These cells are based on ratios and are used in all levels of the piece from the surface rhythm to the large formal divisions. The harmonic language is also described. The vertical harmony is derived from a dense chord presented at the beginning of the piece. The horizontal pitch material is created from small pitch cells, also taken from the opening chord. These cells are used in isolation but are also combined to create modes, which are the focus of the latter parts of the piece.

APA, Harvard, Vancouver, ISO, and other styles

3

Shang, Lei, and lei shang@ieee org. "Modelling of Mobile Fading Channels with Fading Mitigation Techniques." RMIT University. Electrical and Computer Engineering, 2006. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20061222.113303.

Full text

Abstract:

This thesis aims to contribute to the developments of wireless communication systems. The work generally consists of three parts: the first part is a discussion on general digital communication systems, the second part focuses on wireless channel modelling and fading mitigation techniques, and in the third part we discuss the possible application of advanced digital signal processing, especially time-frequency representation and blind source separation, to wireless communication systems. The first part considers general digital communication systems which will be incorporated in later parts. Today's wireless communication system is a subbranch of a general digital communication system that employs various techniques of A/D (Analog to Digital) conversion, source coding, error correction, coding, modulation, and synchronization, signal detection in noise, channel estimation, and equalization. We study and develop the digital communication algorithms to enhance the performance of wireless communication systems. In the Second Part we focus on wireless channel modelling and fading mitigation techniques. A modified Jakes' method is developed for Rayleigh fading channels. We investigate the level-crossing rate (LCR), the average duration of fades (ADF), the probability density function (PDF), the cumulative distribution function (CDF) and the autocorrelation functions (ACF) of this model. The simulated results are verified against the analytical Clarke's channel model. We also construct frequency-selective geometrical-based hyperbolically distributed scatterers (GBHDS) for a macro-cell mobile environment with the proper statistical characteristics. The modified Clarke's model and the GBHDS model may be readily expanded to a MIMO channel model thus we study the MIMO fading channel, specifically we model the MIMO channel in the angular domain. A detailed analysis of Gauss-Markov approximation of the fading channel is also given. Two fading mitigation techniques are investigated: Orthogonal Frequency Division Multiplexing (OFDM) and spatial diversity. In the Third Part, we devote ourselves to the exciting fields of Time-Frequency Analysis and Blind Source Separation and investigate the application of these powerful Digital Signal Processing (DSP) tools to improve the performance of wireless communication systems.

APA, Harvard, Vancouver, ISO, and other styles

4

Choi, Seung-Ho. "Severely Fading MIMO Channels." Thesis, University of Canterbury. Electrical and Computer Engineering, 2007. http://hdl.handle.net/10092/1190.

Full text

Abstract:

In most wireless communications research, the channel models considered experience less severe fading than the classic Rayleigh fading case. In this thesis, however, we investigate MIMO channels where the fading is more severe. In these environments, we show that the coefficient of variation of the channel amplitudes is a good predictor of the link mutual information, for a variety of models. We propose a novel channel model for severely fading channels based on the complex multivariate t distribution. For this model, we are able to compute exact results for the ergodic mutual information and approximations to the outage probabilities for the mutual information. Applications of this work include wireless sensors, RF tagging, land-mobile, indoor-mobile, ground-penetrating radar, and ionospheric radio links. Finally, we point out that the methodology can also be extended to evaluate the mutual information of a cellular MIMO link and the performance of various MIMO receivers in a cellular scenario. In these cellular applications, the channel itself is not severely fading but the multivariate t distribution can be applied to model the effects of intercellular interference.

APA, Harvard, Vancouver, ISO, and other styles

5

Felber, Werner, and Thomas Reuster. "The Fading of Psychosis." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-134488.

Full text

APA, Harvard, Vancouver, ISO, and other styles

6

Felber, Werner, and Thomas Reuster. "The Fading of Psychosis." Karger, 2001. https://tud.qucosa.de/id/qucosa%3A27570.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

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.

Full text

APA, Harvard, Vancouver, ISO, and other styles

8

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.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

Caine, Michael Andrew. "Fading of carbonless copying paper." Thesis, University of Central Lancashire, 1990. http://clok.uclan.ac.uk/20342/.

Full text

Abstract:

The reactions of crystal violet lactone (CVL) (1) and carbazolyl blue (S-RB) (2) were studied on the acid activated clay Fulacolor. The colourless leuco dye CVL (1) undergoes lactone cleavage, when adsorbed on Fulacolor, to give a blue zwitterion. CVL (1) was also shown to adsorb as the unchanged lactone which could be photochemically ring opened. The zwitterion could be displaced readily by water vapour. When a high surface acidity was kept, the zwitterion was more resistant to displacement, the humidity and any exchanged cations being important factors. Prolonged exposure to light causes fading of the zwitterion, the products from which are mainly demethylated species. It was shos.jn that the fading mechanism involves singlet oxygen production, by the dyestuff itself, which subsequently attacks the dye. Singlet oxygen quenchers retarded the fading process. The slow developing dye S-RB (2) was found to have a rate constant for photo-oxidation (at 30 ° C) of approximately twice that of benzoyl leuco methylene blue (BU€) (4), a previously commonly used dye. Addition of the Lewis acid aluminium chloride, - greatly enhanced the rate of production of the dye from S-RB (2),f whereas the weaker Lewis acid boron trifluoride, did in fact retard the dye development. A coordination complex with a different ,tmax for 1absorptionwas detected with boron trifluoride and S-RB (2). The oxIdation of S-RB (2) on Fulacolor was shown to occur at two distinct sites: iron atoms in the aluininosilicate lattice and at aluminium Lewis acid lattice edge sites. A method was devised for promoting the migration of Fe 3 cations back into the damaged octahedral layer of the acid activated montmorillonite Fulacolor, and thus of increasing the rate of S-RB (2) dye development.

APA, Harvard, Vancouver, ISO, and other styles

10

Huang, Guojun. "Signal fading on microwave links." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq21089.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

Raison, Philippe. "Le processus psychique du fading." Paris 7, 2008. http://www.theses.fr/2008PA070047.

Full text

Abstract:

En certaines occurrences liées à la pathologie, maintenir un certain quantum d'excitation à l'intérieur de l'appareil psychique semble impossible. Ce sont ces circonstances que nous tentons de relever, au travers de ce phénomène particulier qu'est le fading. Ce processus psychique est référé à l'inhibition, l'acte et la discordance D'un point de vue psychanalytique, nous remarquons, en séance, que repérer son image dans (l'image de) l'autre échoue. Nous décrivons également, phénoménologiquement (à partir notamment de la notion de "synthèse passive") comment le patient est bien en deçà de toute forme "logicio -eidétique". Qu'est ce qui amène, alors, à cette défaillance au sein des Vorstellungen (représentations) et là où sont en cause ce que Freud a nommé Vorstellungrepraesentanzen (tenants lieu de représentation)? Enfin, nous remarquons au fil des exemples cliniques ce questionnement sur la perception des chose en elles mêmes ainsi que la manifestation de points de violence qui indiquent un certain pouvoir de l'Autre
In some occurrences linked to the pathology, maintaining a certain quantum of excitations inside the mental apparatus seems impossible. We try to note down these circumstances, through this particular phenomenon that fading is. This psychological process is referred to inhibition, act and discordance. From psychoanalytical point of view, in session, we note that to spot our image in (image of) other one fails. We describe, also, from a phenomenological point o view (from notably the notion of ' passive synthesis ") how the patient is well within every "logicio-éidétique" form Then, what lead to the failure inside the "Vorstellungen"(representations) and where are in cause, what Freud had named "Vorstellung repraesentanzen" (supporters place of representations)? Finally, we observe, in the course of clinical examples, this question setting on the perception of the things themselves and also the demonstration of points o violence noting down a certain power of the other One

APA, Harvard, Vancouver, ISO, and other styles

12

Johansson, Gustav. "Concreteness fading for teaching programming." Thesis, Högskolan i Skövde, Institutionen för informationsteknologi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-17372.

Full text

Abstract:

This dissertation presents a study that explores a specific implementation of concreteness fading used in a serious game that teaches programming. Concreteness fading consists of first presenting concepts with concrete representations before swapping them gradually with their concrete, normal counterparts. The goal is to figure out how concreteness fading should be applied to a programming game to have it increase learning. Expert interviews are performed to discuss different aspects of how the technique is utilized in the game Reduct. Participants also play through the game before discussing it. Results show that some found the individual representations of mechanics within the game to be the biggest flaw while others pointed to how it handled the fading aspect. These generally come down to a lack of clarity, and should be considered when developing future games of this style.

APA, Harvard, Vancouver, ISO, and other styles

13

Springer, Michael Leicester. ""Form fading among fading forms" death, language and madness in the novels of Samuel Beckett." Thesis, Rhodes University, 2008. http://hdl.handle.net/10962/d1002240.

Full text

Abstract:

The primary thesis of this dissertation is that the development of narrative strategy and technique through the course of Samuel Beckett’s fictional oeuvre enacts a parody of the Cartesian method of doubt, in which the search for first principles, instead of providing grounds for certainty, is a hopeless, grotesque quest for a self which eludes any and every assertion. My chief concerns are thus, firstly, to explicate and elucidate the nature of such narrative strategies and techniques, and how these can be said to parody epistemological procedure; and secondly, to interrogate the implications of this parody for the epistemological and interpretative endeavour of which the human sciences are comprised. These two issues are explored by way of an examination of Beckett’s earliest novel, Murphy, and the narrative impasse that arises from the contradiction between this work’s largely realist form and quasi-postmodern content. I thereafter argue that the later fiction, most particularly the Trilogy, achieves formal and stylistic solutions to the aesthetic and epistemological challenges raised by the earlier work. Beckett’s fictional oeuvre, I contend, can best be construed as an attempt to attain that which exceeds and escapes narrative in and through narrative, namely madness or death. The achievement of either would entail the obliteration of the possibility of narrating at all, and the novels, engaging in a self-deconstructing endeavour, thus occupy a profoundly paradoxical position. Any attempt to interpret a body of work of this nature can only respond in an analogous manner, by trying to make meaning of the subversion of meaning, and deconstructing the assumptions that inform its procedures. This dissertation argues that it is precisely in the way in which it necessitates such selfreflexive discursive analysis that the import of Samuel Beckett’s fiction lies, and extrapolates the significance of this for an understanding of discourse, literary criticism, and epistemological procedure.

APA, Harvard, Vancouver, ISO, and other styles

14

Chakraborty, Kaushik. "Reliable communication over optical fading channels." College Park, Md. : University of Maryland, 2005. http://hdl.handle.net/1903/2855.

Full text

Abstract:

Thesis (Ph. D.) -- University of Maryland, College Park, 2005.
Thesis research directed by: Electrical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

APA, Harvard, Vancouver, ISO, and other styles

15

Kim, Thanh Tùng. "Quantized Feedback for Slow Fading Channels." Licentiate thesis, KTH, School of Electrical Engineering (EES), 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3952.

Full text

Abstract:

Two topics in fading channels with a strict delay constraint and a resolution-constrained feedback link are treated in this thesis.

First, a multi-layer variable-rate single-antenna communication system with quantized feedback, where the expected rate is chosen as the performance measure, is studied under both short-term and long-term power constraints. Iterative algorithms exploiting results in the literature of parallel broadcast channels are developed to design the system parameters. A necessary and sufficient condition for single-layer coding to be optimal is derived. In contrast to the ergodic case, it is shown that a few bits of feedback information can improve the expected rate dramatically. The role of multi-layer coding, however, reduces quickly as the resolution of the feedback link increases.

The other part of the thesis deals with partial power control systems utilizing quantized feedback to minimize outage probability, with an emphasis on the diversity-multiplexing tradeoff. An index mapping with circular structure is shown to be optimal and the design is facilitated with a justified Gaussian approximation. The diversity gain as a function of the feedback resolution is analyzed. The results are then extended to characterize the entire diversity-multiplexing tradeoff curve of multiple-antenna channels with resolution-constrained feedback. Adaptive-rate communication is also studied, where the concept of minimum multiplexing gain is introduced. It is shown that the diversity gain of a system increases significantly even with coarsely quantized feedback, especially at low multiplexing gains.

APA, Harvard, Vancouver, ISO, and other styles

16

Tan, Christopher Chiu-Hur. "On Markov modeling of fading channels." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0004/MQ28259.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Kerr, Ronald W. "Convolutional ring codes for fading channels." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ32751.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Cheng, Cuifen. "A Nakagami-m fading channel simulator." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq55894.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Kim, Thanh Tùng. "Quantized feedback for slow fading channels /." Stockholm : Communication Theory Laboratory, School of Electrical Engineering, Royal Institute of Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3952.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

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.

Full text

Abstract:

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.)

APA, Harvard, Vancouver, ISO, and other styles

21

Beirouti, Patrick. "Automatic repeat request on fading channels." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61226.

Full text

Abstract:

Automatic repeat request (ARQ) is a widespread technique for error control in data communication systems. This research examines the performance of conventional ARQ schemes over fading channels. The basic Gilbert-Elliott two-state Markov model is used to represent these channels. This basic model is recursively extended to a 2$ sp{n}$-state Markov chain suitable for n-bit block codes. Using this 'Extended Gilbert-Elliot' model, an approximation of the throughput efficiency of the conventional ARQ schemes is derived. This approximation is particularly valid for slow fading channels. Furthermore, performance plots are obtained, showing the effects of channel fading on throughput efficiency: ARQ performance deteriorates with slower fading, or alternatively, higher channel memory. Consequently, frequency-hopped codeword transmission is explored, a technique by which channel memory can be reduced. Throughput performance of frequency-hopped ARQ systems is derived, which shows significant potential improvements over systems with no frequency hopping.

APA, Harvard, Vancouver, ISO, and other styles

22

Baas, Nicholas J. "Decomposition of Rayleigh Fading dispersive channels." Thesis, University of Canterbury. Electrical and Electronic Engineering, 2001. http://hdl.handle.net/10092/5448.

Full text

Abstract:

This thesis identifies, develops and applies methods for the decomposition of fading dispersive channels. Such channels arise in wireless communication as a result of multipath and relative motion of the transmitter, scatterers and receiver. The decompositions considered are the f-power series and Karhunen-Loève (KL) expansions. For the KL expansion generalisations to rapid time variation are possible with the separate options of single spread and double spread decomposition. The single spread decomposition involves a model of the instantaneous channel transfer function with time variation supported by sample spaced coefficients. The double spread decomposition employs a model of each received pulse and requires symbol spaced coefficients. The decompositions are applied to pulse shaping, channel modelling for equalisation and the determination of performance limits for linear modulation over fading dispersive channels. The results on pulse shaping show that, with moderate bandwidth expansion and appropriate design, it is possible to significantly lower the complexity of a mobile receiver. The approach suggests a way to move complexity and power consumption away from the mobile unit and into the base station. The effects of diversity on performance are investigated by assuming a single pulse from a linear modulation format. This removes the need to consider intersymbol interference and allows conclusions about the impact of fading and dispersion on the probability of error and the average mutual information.

APA, Harvard, Vancouver, ISO, and other styles

23

Leon, Wing Seng. "Equalization and estimation for fading channels." Thesis, University of Canterbury. Electrical and Electronic Engineering, 2003. http://hdl.handle.net/10092/6039.

Full text

Abstract:

The main contribution of this thesis is the development of high performing, reduced complexity receivers for fading channels. Three different receiver structures are proposed and they operate without the need of any channel statistics. First, a double filtering receiver for systems employing DPSK modulation on channels with small delay and Doppler spreads is presented. BER performance results obtained via simulations and analysis show that the proposed structure outperforms the conventional matched filtering DPSK detector. Second, a polynomial predictor based sequence detector for flat-fading channels is presented. The receiver consists of a bank of polynomial least squares FIR predictors. The proposed receiver is not restricted only to systems using constant envelope modulation schemes. Analytical and simulated BER results are presented. In some cases, the proposed receiver performs only a few dB worse than an MLSE receiver with known channel statistics. Third, a sequence detector employing the polynomial based GRLS channel estimator is presented. The GRLS estimator is a generalization of the standard RLS algorithm and it requires a state space model of the channel to operate. It is shown that by using a polynomial or t-power series of the channel coefficients, a justifiable state space model may be derived without the need for any channel statistics. An analytical technique to evaluate the tracking performance of the GRLS estimator is also presented. The new analytical method may also be applied to the standard RLS algorithm with improved results. Simulated and analytical results show that in some cases, the tracking performances of the proposed channel estimator is almost as good as that of an optimal Kalman based channel estimator. BER results also indicate that the sequence detector using the proposed GRLS estimator performs just as well as one using a Kalman based estimator.

APA, Harvard, Vancouver, ISO, and other styles

24

van, Nobelen Robert. "Coding for the Rayleigh fading channel." Thesis, University of Canterbury. Electrical and Electronic Engineering, 1996. http://hdl.handle.net/10092/6060.

Full text

Abstract:

The problem of effective coding for the Rayleigh fading channel is addressed. A signal transmitted over the Rayleigh fading channel experiences quasi-periodic deep fades in the signal amplitude, and random phase shifts. The fades in signal amplitude are the cause of error events and limit the bit error rate of an uncoded system to about 10-4 at a signal-to-noise ratio of 30 dB. For applications where a lower error rate is desired, more sophisticated methods of transmission and detection are required. We present an extensive generalised analysis of the probability of error of maximum likelihood sequence estimation techniques for the Rayleigh fading channel This analysis provides the criteria for good code design for the Rayleigh fading channel and we extend the recently developed area of geometrically uniform (GU) codes for the AWGN channel, to the Rayleigh fading channel, and present the results of searches for good GU trellis codes. The concept of geometric uniformity is extended to set of points to form geometrically uniform partitions of signal sets. The GU partitions readily allow powerful multi-level codes to be defined with good distance properties. Multi-level codes have the advantage of outperforming trellis codes in terms of decoding complexity at the cost of greater decoding delay. Good multi-level codes over GU partitions are presented and compared with similarly performing trellis codes. Finally a system is presented which combines the techniques of multiple symbol differential detection (MSDD) with multi-level coding to obtain a good probability of error performance without assuming coherent detection, or ideal channel state information.

APA, Harvard, Vancouver, ISO, and other styles

25

Brown, Colin. "Reduced complexity equalisation for fading channels." Thesis, University of York, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251806.

Full text

APA, Harvard, Vancouver, ISO, and other styles

26

Hinton, Danielle A. (Danielle Ayodele) 1978. "Turbo coding in correlated fading channels." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/87214.

Full text

Abstract:

Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.
Includes bibliographical references (leaves 46-47).
by Danielle A. Hinton.
M.Eng.

APA, Harvard, Vancouver, ISO, and other styles

27

Yeh, Edmund Meng 1971. "Multiaccess and fading in communication networks." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/16789.

Full text

Abstract:

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2001.
Includes bibliographical references (p. 159-163).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Two fundamental issues in the design of wireless communication networks are the interference among multiple users and the time-varying nature of the fading wireless channel. We apply fundamental techniques in information theory and queueing theory to gain insights into the structure of these problems. In a terrestrial cellular or space network, multi-user interference arises naturally as different users in the same cell or region attempt to transmit to the base station or satellite at the same time and in the same frequency range. We first examine the impact of this interference on the design of error correction codes for reliable data transmission. At the physical layer of the wireless network, the phenomenon of multi-user interference is captured by the multiaccess (many-to-one) channel model. The set of all data rates at which reliable communication can take place over this channel is characterized via information theory by the so-called multiaccess capacity region. A basic problem is developing coding schemes of relatively low complexity to achieve all rates in this capacity region. By exploiting the underlying geometrical structure of the capacity region, we develop a method of reducing the multi-user coding problem to a set of single-user coding problems using the ideas of time-sharing and successive decoding. Next, we investigate the effect of multi-user interference on higher-layer quality-of-service issues such as packet delay. Under certain conditions of symmetry, we find that the structure of the multiaccess capacity region can again be used to obtain a "load-balancing" queue control strategy which minimizes average packet delay for Poisson data sources.
(cont.) Due to the mobility of users and constantly changing multipath environments, wireless channels are inherently time-varying, or fading. Any sensible design of wireless networks must take into account the nature of this fading and the ability of the system to track channel variations. We consider a wireless system in which a single user sends time-sensitive data over a slowly varying channel. Information regarding the state of the channel is fed back with some delay to the transmitter, while the receiver decodes messages within some fixed and finite amount of time. Under these conditions, we demonstrate a provably optimal transmission strategy which maximizes the average data rate reliably sent across the wireless channel. The strategy is based on the information-theoretic idea of "successive refinement," whereby the decoder decodes at different rates according to the observed channel state.
by Edmund Meng Yeh.
Ph.D.

APA, Harvard, Vancouver, ISO, and other styles

28

Abou, Faycal Ibrahim C. (Ibrahim Chafik). "Reliable communication over Rayleigh fading channels." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/10648.

Full text

Abstract:

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996.
Includes bibliographical references (p. 73-74).
by Ibrahim C. Abou Faycal.
M.S.

APA, Harvard, Vancouver, ISO, and other styles

29

Asyhari, Agustian Taufiq. "Nearest neighbour decoding for fading channels." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610448.

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

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

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

31

Shukla, Parveen Kumar. "Adaptive equalization of fading radio channels." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47660.

Full text

APA, Harvard, Vancouver, ISO, and other styles

32

Kaltakis, D. "Fundamental limits of GCMAC with fading." Thesis, University of Surrey, 2009. http://epubs.surrey.ac.uk/843695/.

Full text

Abstract:

The scientific field of information theory provides a mathematical framework which aims to quantify the maximum achievable data rate over a communication channel. The underlying mathematical concepts to predict the capacity of a single communication link were developed by Shannon more than half a century ago. The first important attempt to study the capacity of a cellular system was carried out in the last decade. That work by Wyner introduced the concept of Base Station co-operation. The available information theoretic findings are not directly usable to provide realistic estimates for the capacity of practical systems since they cannot model the effect of changes in physical parameters in the environment like path loss exponent and the distance between the adjacent cell sites. The objective of this work is to extend the known formulations for the capacity of the Gaussian Cellular Multiple Access Channel (GCMAC) with joint processing by incorporating path loss and other channel conditions that represent a real communication system and thus to provide a more realistic analytical upper bound for the capacity of the wireless cellular network. In this direction, the available GCMAC model with joint processing and small scale fading is extended by adding multiple antennas at the Base Stations (BSs) and User Terminals (UTs) and by removing the assumption that UTs are co-located at the BS position. Since it is concluded that the available GCMAC model is not sufficient to analyse more complex systems a new model is built which enables the evaluation of the achievable capacity of more realistic systems. Based on this model a new geometric and mathematical model is also developed which enables the study of fairness and user rate distribution in joint processing systems with small and large scale fading. The analysis provides several achievable capacity formulae and some very useful insights on the behavior of the sum rate as well as the fairness, when certain system parameters change, are derived. The formulae can be used to evaluate the achievable sum rate of practical systems employing full BS co-operation, given the parameters that control that capacity.

APA, Harvard, Vancouver, ISO, and other styles

33

Coronel, Pedro E. "Diversity-multiplexing tradeoff in selective-fading channels /." Zürich : ETH, 2008. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17896.

Full text

APA, Harvard, Vancouver, ISO, and other styles

34

Ponce, Testino Ramón. "Ethical Fading and Biased Assessments of Fairness." Thesis, Linköping University, Centre for Applied Ethics, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-9757.

Full text

Abstract:

In this thesis I present and discuss the phenomenon of ethical fading, and its association with biased assessment of a fair action. Ethical fading is an intuitive, self-deceptive, unconscious mechanism by which even morally competent agents are lead to disregard the ethical consequences of a particular choice. In engaging in this psychological mechanism, I argue, agents are also presupposing a biased assessment of entitlement. This biased assessment of fairness is intentionally dubious, and to be found in decision frames and reinforced by contexts. In the final part of the work I present an applied ethics case to show how ethical fading may be a quite prevalent pattern of behavior.

APA, Harvard, Vancouver, ISO, and other styles

35

Li, Xin. "State space estimation of wireless fading channels." Thesis, University of Ottawa (Canada), 2002. http://hdl.handle.net/10393/6096.

Full text

Abstract:

This thesis presents a state space approach to optimal estimation of channel processes, such as inphase, quadrature, square envelope, phase, etc., of wireless fading channels. The models are derived from the Doppler power spectral density using factorization and realization techniques. Several simulations are performed when the channel is Rayleigh and Ricean distributed under both flat and frequency-selective fading assumptions. The simulation studies illustrate the tracking properties of the inphase, quadrature and square envelope estimators for various received signal-to-noise ratios.

APA, Harvard, Vancouver, ISO, and other styles

36

Pokorska, Joanna. "Relationship fading in business-to-consumer context." Thesis, Aston University, 2016. http://publications.aston.ac.uk/28879/.

Full text

Abstract:

The objective of this thesis is to develop a better understanding of the relationship fading phenomenon in business-to-consumer context. Fading relates to a gradual decline in consumer’s willingness to continue a relationship with a company. Therefore, understanding the fading process may help to elucidate the ‘unexplained’ relationship dissolution and customer defection. Led by an assumption that a relationship between a consumer and a brand is like the one between individuals, the thesis proposes that the trajectory of relationship fading reflects the disaffection processes similar to the ones suggested in marital and romantic relationships between individuals. The approach taken to answering this research question is a multi-study approach. This type of approach allows addressing each individual research question independently, using the most appropriate research methods. As a result, the thesis comprises three adjacent studies. All three studies are linked and together contribute to a better understanding of the relationship fading process, which is the main topic of the thesis. Based on the results from the first study, a set of boundary conditions of relationship fading is identified. The results of the second study suggest that predictors of relationship fading stage can be uncovered. Thirdly, different restoration techniques are explored, aiming to describe their effectiveness in various relationship fading stages. Individual objectives of the three studies are accomplished. All three studies contribute to achieving the overall objective of the thesis, namely to developing a better understanding of the phenomenon of relationship fading.

APA, Harvard, Vancouver, ISO, and other styles

37

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.

Full text

APA, Harvard, Vancouver, ISO, and other styles

38

Bradley, Martin James. "Adaptive equalisation for fading digital communication channels." Thesis, Durham University, 1996. http://etheses.dur.ac.uk/5177/.

Full text

Abstract:

This thesis considers the design of new adaptive equalisers for fading digital communication channels. The role of equalisation is discussed in the context of the functions of a digital radio communication system and both conventional and more recent novel equaliser designs are described. The application of recurrent neural networks to the problem of equalisation is developed from a theoretical study of a single node structure to the design of multinode structures. These neural networks are shown to cancel intersymbol interference in a manner mimicking conventional techniques and simulations demonstrate their sensitivity to symbol estimation errors. In addition the error mechanisms of conventional maximum likelihood equalisers operating on rapidly time-varying channels are investigated and highlight the problems of channel estimation using delayed and often incorrect symbol estimates. The relative sensitivity of Bayesian equalisation techniques to errors in the channel estimate is studied and demonstrates that the structure's equalisation capability is also susceptible to such errors. Applications of multiple channel estimator methods are developed, leading to reduced complexity structures which trade performance for a smaller computational load. These novel structures are shown to provide an improvement over the conventional techniques, especially for rapidly time-varying channels, by reducing the time delay in the channel estimation process. Finally, the use of confidence measures of the equaliser's symbol estimates in order to improve channel estimation is studied and isolates the critical areas in the development of the technique — the production of reliable confidence measures by the equalisers and the statistics of symbol estimation error bursts.

APA, Harvard, Vancouver, ISO, and other styles

39

Ibanez, Marc B. (Marc Benedict). "Cellular power control in a fading environment." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/11297.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

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

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

41

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

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

42

Mohanty, Nirode. "Phase Tracking Error in a Fading Channel." International Foundation for Telemetering, 1987. http://hdl.handle.net/10150/615322.

Full text

Abstract:

International Telemetering Conference Proceedings / October 26-29, 1987 / Town and Country Hotel, San Diego, California
The phase tracking error of the reception of a QPSK signal transmitted in a severe fading environment is derived. The phase estimate derived from the phase lock loop (PLL) will be used by a binary phase shift keying (BPSK) receiver for the recovery of the data. The resultant probability of bit error is analyzed, and is shoen to be significantly improved when the phase of the transmitted signal is tracked by a PLL separately and utilized in the coherent detection.

APA, Harvard, Vancouver, ISO, and other styles

43

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

Full text

Abstract:

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

APA, Harvard, Vancouver, ISO, and other styles

44

Kowalski, Shelley. "Fading light : the case of Doris Ulmann /." view abstract or download file of text, 2000. http://wwwlib.umi.com/cr/uoregon/fullcit?p9977907.

Full text

Abstract:

Thesis (Ph. D.)--University of Oregon, 2000.
Typescript. Includes vita and abstract. Includes bibliographical references (leaves 232-242). Also available for download via the World Wide Web; free to University of Oregon users. Address: http://wwwlib.umi.com/cr/uoregon/fullcit?p9977907.

APA, Harvard, Vancouver, ISO, and other styles

45

Kauffman, Amy Lynne. "Stimulus fading within check-in/check-out." Thesis, University of Oregon, 2008. http://hdl.handle.net/1794/8580.

Full text

Abstract:

xi, 111 p. ; ill. (some col.) A print copy of this title is available through the UO Libraries. Search the library catalog for the location and call number.
To address the growing academic and social needs of students, schools must utilize efficient and effective methods of behavior support. Targeted interventions support students who are at-risk for developing more severe problem behaviors. These interventions are implemented similarly across a group of students, and thus serve as an efficient and cost effective method of behavior support. Check in Check out (CICO) is a targeted group intervention that has a growing research base supporting its efficacy (Crone & Horner, 2003; Todd, Campbell, Meyer, & Horner, 2008). Although there is a growing research base, no studies have examined maintenance of reductions in problem behavior upon fading. The present study examines (1) if a functional relation exists between CICO and reductions in problem behavior, and (2) which components of CICO can be successfully faded with reductions in problem behavior maintaining. In addition, this study examines if teacher attention varies across phases of the study, and predicts successful fading procedures. A reversal design was used to evaluate the efficacy of CICO and subsequent fading phases in four elementary school aged boys. Results indicated that CICO was functionally related to reductions in classroom problem behavior in all four participants. In addition, a functional relation was established with CICO and increases in academic achievement in three participants. Fading procedures were mildly successful, with only some intervention components being removed with reductions in problem behavior maintaining. The amount of adult attention did not vary across study phases, however adult attention became less dependent on problem behavior during the CICO and first fading phase. Clinical and conceptual implications, as well as future research will be discussed.
Adviser: Cynthia Anderson

APA, Harvard, Vancouver, ISO, and other styles

46

Menon, Rekha. "Impact of Channel Estimation Errors on Space Time Trellis Codes." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/36490.

Full text

Abstract:

Space Time Trellis Coding (STTC) is a unique technique that combines the use of multiple transmit antennas with channel coding. This scheme provides capacity benefits in fading channels, and helps in improving the data rate and reliability of wireless communication. STTC schemes have been primarily designed assuming perfect channel estimates to be available at the receiver. However, in practical wireless systems, this is never the case. The noisy wireless channel precludes an exact characterization of channel coefficients. Even near-perfect channel estimates can necessitate huge overhead in terms of processing or spectral efficiency. This practical concern motivates the study of the impact of channel estimation errors on the design and performance of STTC.

The design criteria for STTC are validated in the absence of perfect channel estimates at the receiver. Analytical results are presented that model the performance of STTC systems in the presence of channel estimation errors. Training based channel estimation schemes are the most popular choice for STTC systems. The amount of training however, increases with the number of transmit antennas used, the number of multi-path components in the channel and a decrease in the channel coherence time. This dependence is shown to decrease the performance gain obtained when increasing the number of transmit antennas in STTC systems, especially in channels with a large Doppler spread (low channel coherence time). In frequency selective channels, the training overhead associated with increasing the number of antennas can be so large that no benefit is shown to be obtained by using STTC.

The amount of performance degradation due to channel estimation errors is shown to be influenced by system parameters such as the specific STTC code employed and the number of transmit and receive antennas in the system in addition to the magnitude of the estimation error. Hence inappropriate choice of system parameters is shown to significantly alter the performance pattern of STTC.

The viability of STTC in practical wireless systems is thus addressed and it is shown that that channel estimation could offset benefits derived from this scheme.

Master of Science

APA, Harvard, Vancouver, ISO, and other styles

47

Mendu, Arjun. "A New Simulation of Multi-State Fading Channels." Ohio University / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1061239558.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

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.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

Yang, Fan. "Free-space optical communication systems over fading channels." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/56495.

Full text

Abstract:

Free-space optical (FSO) communication systems can provide larger bandwidth and rapid deployment for communication links. Such systems do not interfere with existing radio frequency (RF) systems and can make communication more secure. However, the performance of FSO communication systems is highly dependent on its channel conditions. The atmospheric channels can impose attenuation and scintillation effects on the communication link, and these effects can hinder the correct detection of information on receiver side. In this thesis, we focus on the performance analysis of terrestrial FSO systems over atmospheric fading channels. One successful channel model to fit the experiment data is the lognormal-Rician model, but its widely adoption is impeded by its analytically intractable probability density function (PDF). Therefore we use Padé approximants method to obtain accurate approximations of the PDF, cumulative density function, and moment generating function of lognormal-Rician distribution. Simple closed-form bit-error rate (BER) expression are obtained for binary phase-shift keying (BPSK) modulation with maximum ratio combining (MRC) reception and for binary differential phase-shift keying (DPSK) with selection combing (SC) reception. Asymptotic error rate analysis for BPSK and DPSK is also presented to reveal the performance behavior in large signal-to-noise ratio regimes. The pointing error effects in FSO systems can also contribute to channel impairments. In order to study the influence of pointing error on system performance, we propose a statistical model for pointing error with nonzero boresight error, which takes into account of laser beamwidth, detector aperture size, and jitter variance. A novel closed-form PDF is derived for this pointing error model. Furthermore, we obtain closed-form PDF and series PDF, respectively, for the composite lognormal and Gamma-Gamma turbulence channels with nonzero boresight pointing errors. We conduct error rate analysis of on-off keying signaling with intensity modulation and direct detection over the lognormal and Gamma-Gamma fading channels. The BER results are presented in highly accurate converging series. Asymptotic error rate analysis and outage probability of such a system are also presented based on the derived composite PDFs. It is shown that the boresight error can only affect the coding gain, while the diversity order is determined by either the atmospheric fading effect or the pointing error effect, depending on which effect is more dominant. For subcarrier intensity modulated FSO systems, the carrier phase estimation error (CPE) would degrade the system performance. We study the BER performance of subcarrier M-ary phase-shift keying systems with carrier phase errors (CPE) in lognormal turbulence channels. The CPE is modeled as a Tikhonov random variable. The CPE induced asymptotic noise reference losses for the studied systems are quantified analytically by introducing the lognormal-Nakagami fading as an auxiliary channel model. One effective counter fading technique is spatial diversity, which requires multiple apertures at transmitter or receiver side. We first conduct a diversity analysis on single-branch FSO systems over atmospheric fading channels. We find that the diversity order of an FSO system is usually determined by small scale effects in its fading channels when the irradiance fluctuation can be modeled as a modulation process (K, lognormal-Rician, Gamma-Gamma and M distribution). Based on this observation and the fact that lognormal channel does not have valid diversity order, we propose a lognormal-Nakagami model to facilitate asymptotic analysis on lognormal channels. Using such an approach, we study different multi-branch FSO systems over correlated lognormal fading channels that may have nonidentical variance. We discover that the correlation among the lognormal channels can impose large signal-to-noise ratio (SNR) penalty to system bit-error rate performance, compared to that of a similar system with independent lognormal channels. This property is not shared with the other commonly used fading channels. In addition, we also derive a compact expression for the asymptotic relative diversity order (ARDO) between an L-branch combining system over correlated lognormal channels and a single-branch system. It is found that the ARDO is related to the number of diversity branches as well as entry-wise norm of the covariance matrix of the logarithm of the lognormal channel states. While maximal ratio combing (MRC), equal gain combining (EGC) and selection combining (SC) result in the same ARDO, we find that the coding gain difference between MRC and EGC is negligible, but SC suffers a 10log(L) dB loss.
Applied Science, Faculty of
Engineering, School of (Okanagan)
Graduate

APA, Harvard, Vancouver, ISO, and other styles

50

Curry, Elam. "PERFORMANCE OF DIRECTIONAL MODULATION SYSTEMS IN FADING CHANNELS." International Foundation for Telemetering, 2017. http://hdl.handle.net/10150/627013.

Full text

Abstract:

Physical layer security techniques have received increasing interests in recent years due to their ability to provide additional security and their ability to be combined with conventional higher layer security measures. One such physical layer security technique is the directional modulation (DM), where the goal is to provide unhindered communication in an intended direction while hindering the communication in unintended directions. In this paper, we study the effect of Rician fading on a system employing a DM technique that minimizes the intersymbol distance in unintended directions. The performance of the system is investigated for varying ratios of the line-of-sight and scattered signal power, or Rician K-factors. The effect of Rician fading on the bit error rate (BER) performance in intended and unintended directions is studied.

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Fading'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles