Teses / dissertações sobre o tema "Fading multipath channel"
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Xiao, Heng. "On Modeling of a Mobile Multipath Fading Channel". PDXScholar, 1994. https://pdxscholar.library.pdx.edu/open_access_etds/5054.
Texto completo da fonteWelling, Kenneth. "Coded Orthogonal Frequency Division Multiplexing for the Multipath Fading Channel". International Foundation for Telemetering, 1999. http://hdl.handle.net/10150/608525.
Texto completo da fonteThis paper presents a mathematical model for Coded Orthogonal Frequency Division Multiplexing (COFDM) in frequency selective multipath encountered in aeronautical telemetry. The use of the fast Fourier transform (FFT) for modulation and demodulation is reviewed. Error control coding with interleaving in frequency is able to provide reliable data communications during frequency selective multipath fade events. Simulations demonstrate QPSK mapped COFDM performs well in a multipath fading environment with parameters typically encountered in aeronautical telemetry.
Rice, Michael, Gaston David de, Adam Davis, Gus German e 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.
Texto completo da fonteInitial 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.
Dye, Ricky G., e Lyman D. Horne. "PARAMETER CHARACTERIZATION ON A TELEMETRY CHANNEL INCLUDING THE EFFECTS OF THE SPECULAR RAY". International Foundation for Telemetering, 1995. http://hdl.handle.net/10150/608412.
Texto completo da fonteThe aeronautical channel model is a good candidate for modeling the effects of multipath interference of telemetry signals on test ranges. The aeronautical fading channel model is parameterized by the signal to noise ratio, the Doppler shift and time delay between the specular and direct components, the specular to direct power ratio, the direct to diffuse power ratio, and the bandwidth of the multipath fading process. Segments of weighting signal data measured during a test at Tyndall AFB provide data which can be used to determine typical values of the above parameters in a variety of telemetering environments. In this paper, the set of parameters which most closely model the actual telemetry channel using the Tyndall data is determined.
Paje, Vladimir I. "THE EFFECTS OF CARRIER FREQUENCY AND ANTENNA DIAMETER ON FREQUENCY SELECTIVE MULTIPATH FADING". International Foundation for Telemetering, 2000. http://hdl.handle.net/10150/606502.
Texto completo da fonteThis paper uses ARTM channel sounding data collected at Edwards Air Force Base to investigate the dependency between the characteristics of frequency selective multipath fading and carrier frequency and ground based received antenna diameter. Channel model parameters are obtained from data sets measured at different frequencies and various ground based antenna diameters. The analysis shows that the multipath characteristics do not statistically change between the L-band and S-band carrier frequencies, but do change with antenna diameter. Furthermore, Flight 18 data shows that antenna diversity may be a useful technique to reduce data loss from multipath fading.
Lo, Norm W. K. (Norman Wai Keung) Carleton University Dissertation Engineering Systems and Computer. "Adaptive equalization for a multipath fading channel in the presence of interference". Ottawa, 1994.
Encontre o texto completo da fonteZeydan, 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.
Texto completo da fonteDavis, Adam Todd. "DYNAMIC BEHAVIOR OF MULTIPATH INTERFERENCE IN ARTM CHANNEL SOUNDING DATA". International Foundation for Telemetering, 2000. http://hdl.handle.net/10150/606500.
Texto completo da fonteData collected during July 1999 at Edwards EAFB by the Advanced Range Telemetry (ARTM) program is examined to characterize the dynamic behavior of multipath interference in an aeronautical telemetry channel. Multipath fade events are analyzed in the frequency domain to show how these fades appear, evolve, and disappear from the channel. A channel model and examples from the channel sounding data are used to show the dynamic nature of these fade events. The Doppler power spectrum is used to quantify the exact time-varying nature of the multipath fade events. The coherence time, or the amount of time the channel can be viewed as unchanging, is obtained from the Doppler power spectrum and is calculated to be 100 ms in the data sets examined in this paper. This implies that adaptive multipath mitigation techniques must have an adaptation bandwidth of 10 Hz.
Sung-hoon, Jang, Han Sung-hee e Kim Heung-bum. "Auto-tracking antenna pattern effects on multipath channel model at test range". International Foundation for Telemetering, 2001. http://hdl.handle.net/10150/607672.
Texto completo da fonteTelemetry propagation channel is modeled to predict PCM/FM telemetry receiving signal level at APG(Anheung Proving Ground), ADD(Agency for Defense Development). Channel model is composed of direct wave and reflected wave in sea surface, so-called 2-ray model. Our 2-ray model includes transmitting antenna radiation pattern, auto-tracking antenna radiation pattern, sea surface reflection coefficient and phase depending on incident angle. Vertical and horizontal polarized receiving signal strength is obtained from pre-calculated flight trajectory of transmitter. Calculated results are compared with measured data in real flight test. 2-ray channel model can predict almost identical receiving signal level and calculate starting point of multi-path fading effect. Using these results, receiving system can be moved to more proper position before flight test.
Nelson, N. Thomas. "Probability of Bit Error on a Standard IRIG Telemetry Channel Using the Aeronautical Fading Channel Model". International Foundation for Telemetering, 1994. http://hdl.handle.net/10150/611662.
Texto completo da fonteThis paper analyzes the probability of bit error for PCM-FM over a standard IRIG channel subject to multipath interference modeled by the aeronautical fading channel. The aeronautical channel model assumes a mobile transmitter and a stationary receiver and specifies the correlation of the fading component. This model describes fading which is typical of that encountered at military test ranges. An expression for the bit error rate on the fading channel with a delay line demodulator is derived and compared with the error rate for the Gaussian channel. The increase in bit error rate over that of the Gaussian channel is determined along with the power penalty caused by the fading. In addition, the effects of several channel parameters on the probability of bit error are determined.
de, Gaston David E. "BIT ERROR PERFORMANCE ANALYSIS OF BPSK IN THE PRESENCE OF MULTIPATH FADING". International Foundation for Telemetering, 2000. http://hdl.handle.net/10150/606793.
Texto completo da fonteThe presence of multipath fading has been shown to degrade the performance of a wireless channel. This paper quantifies the effects of multipath interference on signal performance based on the estimated parameters of the multipath signal. Theoretical results are compared with actual results obtained through the Advanced Range Telemetry (ARTM) program.
Rice, Michael, Adam Davis e Christian Bettwieser. "A WIDEBAND CHANNEL MODEL FOR AERONAUTICAL TELEMETRY — PART 2: MODELING RESULTS". International Foundation for Telemetering, 2002. http://hdl.handle.net/10150/606289.
Texto completo da fonteThis paper is the second of two papers that present a multipath channel model for wideband aeronautical telemetry. Channel sounding data were collected at Edwards AFB, California at both L-Band and lower S-Band. Frequency domain analysis techniques were used to evaluate candidate channel models. The channel model is composed of three propagation paths: a line-of-sight path, and two specular reflections. The first specular reflection is characterized by a relative amplitude of 70% to 96% of the line-of-sight amplitude and and a delay of 10 – 80 ns. This path is the result of “ground bounces” off the dry lake bed at Edwards and is a typical terrain feature at DoD test ranges located in the Western USA. The amplitude and delay of this path are defined completely by the flight path geometry. The second path is a much lower amplitude path with a longer delay. The gain of this path is well modeled as a zero-mean complex Gaussian random variable. The relative amplitude is on the order of 2% to 8% of the line-of-sight amplitude. The mean excess delay is 155 ns with an RMS delay spread of 74 ns.
Ndzi, David Lorater. "Statistical characterization of a wideband transhorizon link at 11.64 GHz". Thesis, University of Portsmouth, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242520.
Texto completo da fonteLandon, David. "DOPPLER BANDWIDTH CHARACTERIZATION OF ARTM CHANNEL SOUNDING DATA". International Foundation for Telemetering, 1999. http://hdl.handle.net/10150/608760.
Texto completo da fonteData from ARTM channel sounding test flights is examined to characterize the dynamic channel behavior of aeronautical telemetry channels. The dynamic behavior is characterized using the Doppler power spectrum. The width of the Doppler power spectrum is the Doppler bandwidth of the channel which indicates the required bandwidth of adaptive detection techniques such as adaptive equalization, adaptive modulation, adaptive channel selection and adaptive error control coding. Data collected from ARTM Flight 11 suggest a Doppler bandwidth exceeding 6.7 Hz for the channel, but greater accuracy and resolution will only be possible with more data.
Rice, Michael, Adam Davis e Christian Bettwieser. "A WIDEBAND CHANNEL MODEL FOR AERONAUTICAL TELEMETRY — PART 1: GEOMETRIC CONSIDERATIONS AND EXPERIMENTAL CONFIGURATION". International Foundation for Telemetering, 2002. http://hdl.handle.net/10150/606288.
Texto completo da fonteThis paper is the first of two papers that present a multipath channel model for wideband aeronautical telemetry. Channel sounding data, collected at Edwards AFB, California at both L-Band and lower S-Band, were used to generate channel model. In Part 1, analytic and geometric considerations are discussed and the frequency domain modeling technique is introduced. In Part 2, the experimental results are summarized and a channel model composed of three propagation paths is proposed.
Montaquila, Roberto V., Ivan Iudice e Vittorio U. Castrillo. "Design of a Radio channel Simulator for Aeronautical Communications". International Foundation for Telemetering, 2012. http://hdl.handle.net/10150/581633.
Texto completo da fonteThe goal of this paper is to implement a model of multipath fading in a radio channel simulator for aeronautical applications. When developing a wireless communications system, it is useful to perform simulations of the radio context in which the system has to operate. A radio link is substantially composed by three parts: transmitting segment, transmission channel and receiving segment. We focus our attention on the radio channel propagation. We proposed two geometrical models of a territory corresponding to a determined flight area and, after importing the data needed to estimate our parameters, we compared our results with the channel soundings in literature, obtaining comparable values.
Teal, Paul D., e p. teal@irl cri nz. "Real Time Characterisation of the Mobile Multipath Channel". The Australian National University. Research School of Information Sciences and Engineering, 2002. http://thesis.anu.edu.au./public/adt-ANU20020722.085502.
Texto completo da fonteCalatrava, Helena, e 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.
Texto completo da fonteNu 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
Mwangi, Patricia A. W., Amr Haj-Omar e Kishan Montaque. "SIMULATION OF THE AERONAUTICAL RADIO CHANNEL FOR TELEMETRY APPLICATIONS". International Foundation for Telemetering, 2006. http://hdl.handle.net/10150/604033.
Texto completo da fonteThe aeronautical channel is an air to ground channel characterized by multipath, high doppler shifts, Rayleigh fading and noise. Use of a channel sounder ensures proper estimation of the parameters associated with the impulse response of the channel. These estimates help us to characterize the radio channels associated with aeronautical telemetry. In order to have a satisfactory channel characterization, the amplitudes, phase shifts and delays associated with each multipath component in the channel model must be determined.
Landon, David. "PARAMETRIC ESTIMATION OF THE SCATTERING FUNCTION FOR ARTM CHANNEL SOUNDING DATA". International Foundation for Telemetering, 2000. http://hdl.handle.net/10150/608249.
Texto completo da fonteParameterized data from ARTM channel sounding test flights are used to derive a parameter-based estimate of the scattering function. The Doppler bandwidth and Doppler spread, important measures of channel dynamics, can be estimated from such a scattering function. Data collected from ARTM Flight 11 suggest that the Doppler bandwidth is larger than 6.7 Hz. Even for very small collections of parameterized data, surprising agreement is shown to non-parametric scattering function estimates. This confirms modeling assumptions and offers a way to achieve significant reductions of storage requirements.
Abd, El-Sallam Amar. "Low order channel estimation for CDMA systems". Curtin University of Technology, Department of Electrical and Computer Engineering, 2005. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=16299.
Texto completo da fonteThe 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.
Pirinen, P. (Pekka). "Effective capacity evaluation of advanced wideband CDMA and UWB radio networks". Doctoral thesis, University of Oulu, 2006. http://urn.fi/urn:isbn:9514282701.
Texto completo da fonteSmallcomb, Joseph Michael. "Spread spectrum communication over a fading multipath HF channel using transform domain signal processing and a transmitted reference signal". Ohio : Ohio University, 1992. http://www.ohiolink.edu/etd/view.cgi?ohiou1173756311.
Texto completo da fonteCeballos, Emmanuel Gonzales. "A Novel Adaptive Multilevel - Quadrature Amplitude Modulation (M-QAM) Receiver Using Machine Learning to Mitigate Multipath Fading Channel Effects". Thesis, California State University, Long Beach, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10784157.
Texto completo da fonteThe demand for faster speed and greater signal strength of today’s wireless broadband technology evolved signaling techniques to improve spectral bandwidth efficiency. In wireless digital communications, higher-order of M-QAM technique has been employed to improve bandwidth and channel efficiency of the signaling. However, wireless broadband communications such as mobile phones and wireless access networks are prone to multipath fading channel. Higher-order M-QAM is very susceptible to this fading channel because it affects both the amplitude and carrier phase of the transmitted signal as it induces non-linearity.
In this study, an innovative approach in M-QAM demodulation technique has been proposed. This thesis investigated the performance of a proposed modified Costas Loop M-QAM receiver that employed Machine Learning using multi-layer perceptron (MLP) with error-back propagation (EBP) as an adaptive amplitude fading estimator and, using fuzzy logic as loop filter in the phase lock loop (PLL) circuit that estimated the distorted carrier phase of a received signal. A computer simulation of the proposed receiver was developed to investigate the performance of the receiver’s signal recovery over Rayleigh fading channel. The results showed that the ML algorithm tracked well the phase noise and the bit-error rate (BER) were comparable to the theoretical M-QAM curve on certain values of signal-to-noise (SNR) levels.
Shang, Lei, e 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.
Texto completo da fonteHorne, Lyman D., e Ricky G. Dye. "AN INEXPENSIVE DATA ACQUISITION SYSTEM FOR MEASURING TELEMETRY SIGNALS ON TEST RANGES TO ESTIMATE CHANNEL CHARACTERISTICS". International Foundation for Telemetering, 1995. http://hdl.handle.net/10150/608407.
Texto completo da fonteIn an effort to determine a more accurate characterization of the multipath fading effects on telemetry signals, the BYU telemetering group is implementing an inexpensive data acquisition system to measure these effects. It is designed to measure important signals in a diversity combining system. The received RF envelope, AGC signal, and the weighting signal for each beam, as well as the IRIG B time stamp will be sampled and stored. This system is based on an 80x86 platform for simplicity, compactness, and ease of use. The design is robust and portable to accommodate measurements in a variety of locations including aircraft, ground, and mobile environments.
Paje, Vladimir Ignacio. "Equalization Techniques For Multipath Mitigation in Aeronautical Telemetry". Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd774.pdf.
Texto completo da fonteGao, Wei, Shih-Ho Wang e Kamilo Feher. "TESTS AND EVALUATIONS OF ADAPTIVE FEHER EQUALIZERS FOR A LARGE CLASS OF SYSTEMS, INCLUDING FQPSK". International Foundation for Telemetering, 2000. http://hdl.handle.net/10150/606772.
Texto completo da fonteDesign and performance evaluation of a low-complexity equalizer for recently standardized spectral efficient Feher patented quadrature phase shift keying (FQPSK) system [1] over multipath fading channel is presented. The implementation based on a Feher patented equalizer (FE) [1] is of a structure with three branches, which are individually used to compensate for a moving fade notch with different locations. These branches are switched by the control signal that is generated based on pseudo-error on-line detection technique. It is demonstrated that for typical aeronautical telemetry RF frequency selective fading channels, having delay spreads in 20 – 200 ns range, the adaptive FE reduces the number of statistical outages by more than 60% without the need for training bits and without increasing the receiver synchronization time.
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.
Texto completo da fonteFirst, 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.)
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.
Texto completo da fonteSng, Sin Hie. "Radio channel modeling for mobile ad hoc wireless networks". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Jun%5FSng.pdf.
Texto completo da fonteThesis advisor(s): Murali Tummala, Roberto Cristi. Includes bibliographical references (p. 71). Also available online.
Chang, Ihn Kiel. "Antijam spread-spectrum communications over multipath-fading channels". Diss., Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/15453.
Texto completo da fonteSamuel, 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.
Texto completo da fonteZhang, Tingting. "Space time transceiver design over multipath fading channels". Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/11964.
Texto completo da fonteSaid, 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.
Texto completo da fonteSilva, Vanderlei Aparecido da. "Modelagem computacional de canais de comunicação móvel". Universidade de São Paulo, 2004. http://www.teses.usp.br/teses/disponiveis/3/3142/tde-19112004-172238/.
Texto completo da fonteComputational modelling is a powerful and widely used tool for research in mobile communication systems. In such systems, the communication channel modelling is an indispensable factor, because its mobility and propagation characteristics can cause distortion over the transmitted waveform. This work contains the main mathematical and computing communication channel models. A historical cover is provided, which presents the nature of the problem and the initial modelling of the fading phenomenon. On the other hand, recent models are presented, which are mathematically effective and computationally efficient. One contribution of this work is the proposal of a new fading channel computational model, which was suitably tested and validated. The presented models were mathematically analyzed through its statistical properties. From numerical and computational point of view, the models were analyzed through several simulations. The main conclusion, from analytical and simulated results, shows that two models using frequency filtering are the best choice for the generation of multiple uncorrelated Rayleigh fading waveforms, where one of them is the new proposed model. This work can help mobile communications researchers to suitably model the communication channel in a computer simulation.
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.
Texto completo da fonteMella, 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.
Texto completo da fonteMultipath 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.
Zeng, Zong-Yang, e 曾宗揚. "Blind Adaptive Channel Shortening and Frequency Domain Equalizations in Multipath Fading Channels". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/47267017287840433475.
Texto completo da fonte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.
Wu, Yi-Cheng, e 吳翼丞. "Interleaver design for IDMA system under multipath fading channel". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/91078144521377616687.
Texto completo da fonte中原大學
電子工程研究所
103
Interleave-division multiple access (IDMA) is a new wireless communication technique which has been recently discussed in the research field of communications. In IDMA system, interleavers play a key role. Such as code-division multiple access (CDMA) system which different users use different spreading codes, for the IDMA system, different users employ user- specific interleaver to distinguish different users. IDMA system inherits a number of advantages from CDMA system. Recent studies indicate that the performance of IDMA system is better than that of CDMA system. In this paper, we compare the performance of different kinds of interleavers for IDMA system. Besides, we design a new interleaving scheme to enhance the system performance. We also consider the size of interleaver which influences the system performance. Furthermore, the IDMA receiver uses a low cost iterative chip-by-chip multiuser detection algorithm. Finally, we will show the performance results by simulation under the multipath fading channel.
YEN, TSO-CHIUNG, e 葉作瓊. "Adaptive Diversity and Decision feedback MAPSD at multipath fading channel". Thesis, 1998. http://ndltd.ncl.edu.tw/handle/14989294236614333384.
Texto completo da fonteChang, Chi-Lung, e 張吉隆. "Vector Channel Estimation and Data Detection for Multiuser MIMO CDMA in Multipath Fading Channels". Thesis, 2004. http://ndltd.ncl.edu.tw/handle/31322645504317285353.
Texto completo da fonte國立臺北科技大學
電腦通訊與控制研究所
92
Recently, a training-based vector channel estimation scheme has been proposed in [5] for single-user long-code [10] CDMA systems. In this thesis, we extend it to multiuser MIMO CDMA systems where both the transmitter and receiver have multiple antennas. We use the MMSE multiuser detector to suppress multiuser interference and multiple transmit antennas take turns to deliver the training sequences to get good initial channel estimation. In the data transmission period, we combine the MMSE multiuser detector with the maximum likelihood (ML) MIMO detector for multiuser MIMO CDMA systems. The simulation results show that the vector channel estimator outperforms scalar channel estimation in multiuser MIMO CDMA systems.
Chen, Li-Mei, e 陳麗美. "Adaptive Multiuser DFE with Channel Estimation for DS-CDMA Systems in Fading Multipath Channels". Thesis, 2000. http://ndltd.ncl.edu.tw/handle/18595638268373486404.
Texto completo da fonte國立清華大學
電機工程學系
89
The adaptive detector design problem for the direct sequence code division multiple access (DS-CDMA) systems in fading multipath channels is addressed in this dissertation. An adaptive multiuser detector with decision-feedback equalizer (DFE) architecture has been proposed to perform in the fading multipath channels. A tapped-delay-line filter with time-varying tap coefficients is used to model the fading multipath channels and each tap coefficient is modeled as a Rayleigh fading process. The fading multipath channels are estimated by some channel estimation algorithm. Then, the estimates are used for the multiuser DFE design. The main results are summarized as follows: Firstly, a symbol detection equation and channel estimation equation of DS-CDMA systems are given for the purposes of detector design and channels estimation, respectively. The channel estimation equation as well as the dynamics of fading multipath channels forms a novel state-space equation which is utilized to estimate the fading multipath channels precisely. Three situations about the fading multipath channels, including the known channel model, the partially known channel model and the unknown channel model, are considered. Secondly, we discuss two kinds of adaptive multiuser DFEs. One is the directly adaptive multiuser DFE via a one-stage recursive least-squares (RLS) design algorithm. The other is the channel-estimation-based adaptive multiuser DFE via a two-stage channel-estimator/minimum-mean-square-error (CE/MMSE) design algorithm, in which the tap weights of the DFE are adjusted by a channel estimator. For the case of the known channel model, a Kalman channel estimation algorithm is presented for the fading multipath channel estimation. We take not only the estimates of channel but also the statistics of the channel estimation errors into consideration of the DFE design. For the case of partially known channel model, an H_infty channel estimation algorithm is proposed to treat the uncertainties of channel parameters. For the case of unknown channel model, a weighted RLS (WRLS) channel estimation algorithm is proposed to estimate the fading multipath channels. Then, the estimates of channels are used to design the adaptive multiuser DFE via an MMSE criterion. Thirdly, we make a comparison among the directly, the channel-estimation based adaptive multiuser DFE and the optimal MMSE DFE via an abstract analysis. The optimal MMSE DFE means that the time-varying channel response are well-known for the equalizer. We also show that the directly and the channel-estimation-based adaptive multiuser DFEs are different realizations of the optimal MMSE DFE. Owing to their implementations, the proposed two-stage channel-estimation-based adaptive multiuser DFE has better tracking ability for the time-variations of fading channels and performs better than the directly adaptive one. The signal-to-interference-and-noise-ratio (SINR) performance and the bit-error-rate (BER) performance are also presented with the consideration of the impact of the imperfect channel estimation. Finally, two computer simulations examples are given. One is simulated under the land-mobile fading channel model and the other is simulated under the Butterworth fading channel model. The BER performance are investigated with the influences of channel SNR, the length of time-dispersive channel, the number of users, the fading rate of channels, the sensitivity to the uncertainties of channel parameters.
Chang, Cheng-Hseng, e 張正炫. "Timing Recovery on Multipath Fading Channel Using Digital Phase Locked Loop". Thesis, 1998. http://ndltd.ncl.edu.tw/handle/00107591466109502103.
Texto completo da fonteCheng, Shun-Wun, e 鄭舜文. "Estimation of Multipath Fading Channels for Carrier Aggregation OFDM Systems Based on Parametric Channel Modeling". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/22638160667139159899.
Texto completo da fonte國立臺灣大學
電信工程學研究所
100
In order to overcome the multipath fading, channel estimation plays a very important role on the wireless communication systems. Besides, we usually apply orthogonal frequency division multiplexing (OFDM) systems in wireless transmissions because of its advantage in lessening the effect of the multipath fading. Carrier aggregation (CA) is recently a direct solution for providing users with wider transmission bandwidth. Thus, pilot-aided channel estimation for CA OFDM systems is considered in this thesis. We proposed a pilot-aided channel estimation based on parametric channel modeling for CA OFDM systems. Our approach is based on the parametric channel estimator. Specifically, we first use the minimum description length (MDL) criterion to determine the number of paths in the channel. Then, we exploit the estimation of signal parameters by rotational invariance techniques (ESPRIT) to estimate the multipath time delays. With information of the multipath time delays, a minimum mean-square-error (MMSE) estimator is used to estimate the multipath gains. In the above-mentioned process, we combine it with the cooperation between different transmission bands and the compensation of path underestimation for improving the channel estimation performance and reducing the computational complexity. Finally, simulation results show that the proposed method outperforms previously reported methods when the channel model is properly chosen and is time-invariant.
Liu, Jing-Yi, e 劉靜宜. "Design and Implementation of a channel estimation and block equalization system over multipath fading channels". Thesis, 2002. http://ndltd.ncl.edu.tw/handle/28290472892686299569.
Texto completo da fonte國立雲林科技大學
電子與資訊工程研究所碩士班
90
In this thesis, we propose a block based channel equalizer design suitable for wireless communication over ISI and Rayleigh fading channels. The proposed design consists of a Match Filter (MF), a Channel Estimator (CE) and a Block based Decision Feedback Equalizer (BDFE). The channel estimator is based on a semi-blind scheme using RLS algorithm. The estimated channel information is then used in both match filtering and the coefficient update in BDFE. The BDFE is composed of a noise whitener, a maximum-likelihood block detector and a symbol detector. The coefficient update, obtained by Cholesky factorization of the channel matrix, is performed in a block-by-block basis. This will not only reduce the computing complexity when compared with the symbol-based approach, but also enhance the computing concurrency for the possible hardware implementation. We also conduct a wide range of simulations over various channel models containing both ISI and Rayleigh fading effects. Based on the simulation results, the channel equalizer architecture is revised and an efficient systolic array design is derived for hardware implementation in FPGAs. For the channel estimator design, two versions of QRD-RLS algorithm are actually implemented, one as the conventional one and the other as division and square root free. For the BDFE design, we take advantage of the Toeplitz matrix property and adopt a modified Schur algorithm to solve the Cholesky factorization problem. An efficient systolic array design, scalable to any matrix size, is also derived. Finally, all the developed designs are implemented in Xilinx Virtex series FPGAs to verify the hardware performance. The results indicate a channel equalizer system capable of working at 35MHz and processing over 3 million symbols per second.
Chen, Tsung-wang, e 陳宗旺. "Performance Analyses of OCHM Systems Using Perfect Sequences in Multipath Fading Channel". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/46208568695181415233.
Texto completo da fonte國立中山大學
通訊工程研究所
95
In this thesis, the perfect sequence is adopted for the multi-path interference cancellation in orthogonal code hopping multiplexing (OCHM) systems. In traditional OCHM systems, Walsh-Hadamard sequences are adopted for signal spreading. Unfortunately, orthogonality of the Walsh-Hadamard sequences is lost in multi-path fading channels, leading to significant increase in interference. On the other hand, perfect sequences maintain their orthogonality even if synchronization is lost in multi-path fading channels. In this thesis, the signal to interference ratio (SIR) is analyzed mathematically for systems with multiple users. In addition, simulation experiments are conducted to obtain the bit error rate.
Yao-Cheng, Shih, e 施耀程. "A Signal-Processing Antenna Array for Wireless CDMA on Multipath Fading Channel". Thesis, 1998. http://ndltd.ncl.edu.tw/handle/67555113093780377396.
Texto completo da fonte國立臺灣科技大學
電子工程技術研究所
86
This thesis proposes a base station antenna array receiver applied inthe code division multiple access (CDMA) mobile communication systems.The proposed receiver basically consists of a front-end beam-former associatedwith a Gamma-filter based equalizer. This technique isused to reduce thedegradation due to multipath fading channel and the correlation of fadingsignals at antenna elements. The Rayleigh fading channel problem causedby user travelling is considered. We concentrate on real-time trackingthe first-arrived signals from the desired user. A recursive, and numericallystable algorithm is employed to estimate the array response vector and theoptimum beam-forming weights. On the other hand, the recursive least square(RLS)algorithm is used to implement the equalizer. The computer simulations examinethe performance under various Doppler shift and scattering angle and the resultsof the proposed scheme are compared with those of the conventional 2-D RAKEreceiver and the transversal filter.
Wang, Shao-Yu, e 王卲郁. "Performance Analysis of OFDM Over Multipath Fading Channel for Mobile Communication System". Thesis, 2002. http://ndltd.ncl.edu.tw/handle/57704604282126098928.
Texto completo da fonte國立海洋大學
航運技術研究所
90
The performance of OFDM in wireless wideband communication system has been investigated in this project, in terms of bit error rate, through multipath fading channel. However, in wireless data communication systems, orthogonal phase modulation schemes are selected, whereas a loss of orthogonality due to the multipath fading channel, which leads to the transmitted signal bears the effect of frequency-selective fading channel. Although OFDM is a widely recognized method for combating the effect of frequency-selective fading, this paper also evaluates the performance using various number of subcarriers and symbol sampling rate to suppress the inter-subcarrier interference. Design of various roll-off factor of root raised cosine filter is also used. Both system designs and implementation of channel modeling were realized by using ADS system simulation tool for inter-subcarrier interference analysis, with specific orthogonality constraints.
陳怡雯. "A Study on Multi-Carrier CDMA System in Multipath Rayleigh Fading Channel". Thesis, 2001. http://ndltd.ncl.edu.tw/handle/45718456584642935615.
Texto completo da fonte中華大學
電機工程學系碩士班
89
In wireless communication systems, all spread spectrum signals will undergo the frequency-selective fading channel. In order to reduce the effect of this type of fading on system performance, the multicarrier code division multiple access (MC-CDMA) system is developed. The MC-CDMA system utilizes orthogonal frequency division multiplexing (OFDM) to divide the channel into many narrowband subchannels, such that each subchannel only undergoes flat fading, this in turn can also reduce the receiver complexity. This thesis simulates the BER performance of MC-CDMA system with four different combining strategies which include orthogonality restoring combining (ORC), equal gain combining (EGC), maximum ratio combining (MRC), and minimum mean square error combining (MMSEC). The results show that MMSEC is the optimum combining method in the MC-CDMA system. We also simulate the traditional Direct-Sequence (DS) CDMA system for comparison. Our results demonstrate that MC-CDMA outperforms the DS-CDMA system. In addition, we also consider the effect of intersymbol interference (ISI). The results show that as long as the signal duration is larger than the delay spread, ISI influence is insignificant.