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Dissertations / Theses on the topic 'Fast fading channels'
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1
WANG, YING. "PILOT SYMBOL-BASED WAVELET COMMUNICATIONS FOR WIDEBAND FAST-FADING CHANNELS." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1148319204.
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Taylor, Douglas. "Advanced demodulation techniques for digital audio broadcast signals over fast fading channels." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0020/MQ48185.pdf.
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Patenaude, François. "Timing recovery for continuous phase modulation transmitted over fast flat-fading channels." Thesis, University of Ottawa (Canada), 1990. http://hdl.handle.net/10393/5617.
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The problem of deriving symbol synchronization information from the received signal for a class of bandwidth efficient continuous phase modulation (CPM) schemes transmitted over a fast flat-fading channel is studied. The modulation class considered is M-ary CPM with a modulation index h = 1/M. A particular synchronizer structure which generates a tone at the symbol rate in a manner which automatically cancels the fading phase effects is proposed and analyzed in detail. The practical aspects of implementing this synchronizer using digital signal processing methods are discussed. Finally, simulation results showing the root mean square jitter produced by this synchronizer for a few well-known cases of modulation and fading channel parameters are presented to illustrate the performances of the system.
4
Green, Mary Ellen. "Performance of fast frequency-hopped self-normalized BFSK receivers over Ricean fading channels with multitone interference." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1995. http://handle.dtic.mil/100.2/ADA303228.
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Thesis (M.S. in Electrical Engineering) Naval Postgraduate School, June 1995.<br>Thesis advisor(s): R. Clark Robertson, Ralph Hippenstiel. "June 1995." Includes bibliographical references. Also available online.
5
Moon, Todd K., and Chet Lo. "Bandwidth Efficient Signaling Using Multiscale Wavelet Functions and its Performance in a Rician Fast Fading Channel Employing Differential Detection." International Foundation for Telemetering, 1999. http://hdl.handle.net/10150/608755.
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International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada<br>In this paper, orthogonal wavelets are employed to produce multiscale signaling. It is shown that signaling using these functions is bandwidth efficient compared other signaling schemes, including SFSK and GMSK. For signaling in Rician fast fading channel, it is also shown that scaling functions is superior in term of achieving low level of probability of error. Even for multiscale signaling, the level probability of error achieved by using wavelet is lower than conventional flat-top signaling. The benefits are largest for channels with small B(D)T , in which the degradation due to fading is most severe.
6
Riley, John F. "Performance of a fast frequency-hopped noncoherent MFSK receiver with ratio-statistic combining over Rician fading channels with partial-band interference." Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/30966.
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Approved for public release; distribution is unlimited<br>An error probability analysis is performed for a fast frequency- hopped, frequency-shift keyed noncoherent receiver with ratio-statistic combining for a Rician channel with partial-band interference. Results are obtained for binary and M-ary FSK receivers where M is 4, 8, or 16. Both envelope and square-law detectors were analyzed. The probability of bit error is examined for different levels of diversity, thermal noise, severity of fading, fractions of bandwidth jammed, and varying jamming power. Comparisons for the different parameters are done to determine when diversity should be used. For the special case when there is no diversity, an analytic expression for receiver performance is obtained, and the performance of a receiver using envelope detection is found to be identical to that of a receiver using square-law detection for this special case. The results show that, for diversities of three and four, the envelope detector performs better than the square-law detector. It is shown that, for low signal-to-jammer ratios, diversity is generally a disadvantage, and for high signal-to-jammer ratios, diversity is generally an advantage. The transition is dependent on thermal noise and the value of M. Ratio-Statistic Combining, Fast Frequency-Hopping, Rician Fading, FSK modulation, Partial-Band Interference.
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Sheltry, Joseph Francis. "Performance of a fast frequency-hopped noncoherent MFSK receiver over Rician fading channels with either partial-band interference or multi-tone interference." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA286168.
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Thesis (M.S. in Electrical Engineering) Naval Postgraduate School, September 1994.<br>Thesis advisor(s): R. Clark Robertson. "September 1994." Includes bibliographical references. Also available online.
8
Iwasaki, Hidetoshi. "Performance of a fast frequency-hopped noncoherent MFSK receiver with non-ideal noise normalization combining over Ricean fading channels with partial-band interference." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA284989.
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Thesis (M.S. in Electrical Engineering and M.S. in Systems Engineering) Naval Postgraduate School, September 1994.<br>Thesis advisor(s): R. Clark Robertson. "September 1994." Includes bibliographical references. Also available online.
9
Vece, Thomas W. "Effects of non-uniform windowing on the performance of a fast frequency-hopped noncoherent MFSK receiver over Rician fading channels with partial-band interference and Doppler shift." Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/28147.
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Approved for public release; distribution is unlimited<br>An error probability analysis is done for a DFT based, M-ary frequency-shift keying (MFSK) communications system employing fast frequency-hopped spread spectrum signals. A linear combination procedure referred to as noise-normalization is employed at the receiver to minimize the effects of partial-band interference, which is modeled as additive Gaussian noise. The performance of the receiver is studied as a function of signal Doppler shift and type of windowing used in the DFT. The use of fast frequency-hopped spread spectrum is found to improve the performance of the DFT based receiver in all but the most severe cases of Doppler shift. The use of a non-uniform window (i. e., a Hamming window) to improve receiver performance is effective only in the presence of large Doppler shifts. The amount of Doppler shift necessary to warrant the use of a non-uniform window depends on the amount of jamming noise power at the receiver, but is relatively insensitive to the frequency hop rate used
10
Pavlicek, Parker. "Semantic Security for the Fast Fading Wiretap Channel." Thesis, North Dakota State University, 2018. https://hdl.handle.net/10365/28742.
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We provide a set of semantically secure achievable rates for the fast fading wiretap channel. In particular, we do so for the cases where there is channel state information at the transmitter (CSIT) for both the main and eavesdropper channels (full CSIT), for only the main channel (partial CSIT), and for neither channel (statistical CSIT). In the case of partial CSIT and statistical CSIT fast-fading channels, we show that this coding scheme can achieve the best known achievable rates. In the case of full CSIT fast-fading wiretap channels, we show that this coding scheme can actually achieve the secrecy capacity. In particular, this implies that the semantic secrecy capacity for these channels is equivalent to the weak and strong secrecy capacities. Moreover, we achieve these rates in a way that is non-invasive to existing systems and also happens to be explicitly given as well as efficient in implementation.
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Bikhazi, Nicolas W. "MIMO Communication Capacity: Antenna Coupling and Precoding for Incoherent Detection." Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1600.pdf.
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Spilchen, Elizabeth Donna Carleton University Dissertation Engineering Systems and Computer. "Diversity combining for M-ary fast frequency hopping in a multiple- access AWGN and Rayleigh fading channel." Ottawa, 1996.
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Betancourt, R. Miguel A. "Coded performance of a fast frequency-hopped noncoherent BFSK ratio statistic receiver over a Rician fading channel with partial-band interference." Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/23568.
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Approved for public release; distribution is unlimited<br>A frequency-hopping binary frequency shift keying (BSFK) ratio-statistic receiver with multihops per data bit is an effective electronic counter-countermeasures (ECCM) system against partial-band jamming interference. Interference is modeled as Gaussian noise. Orthogonal binary signaling and independent fading diversity is considered over frequency-nonselective, slow fading Rayleigh, Rician, and Gaussian channels. A forward error correcting coding scheme is implemented for a 1/2 rate convolutional code algorithm. The probability of bit error is examined for different levels of diversity, thermal noise, severity of fading, fraction of bandwidth jammed, and jamming power. Uncoded and coded system comparisons are done to determine worst case performance.
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Wan, Ping. "Channel estimation for OFDM in fast fading channels." Thesis, 2011. http://hdl.handle.net/1828/3413.
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The increasing demand for high data rate transmission over broadband
radio channels has imposed significant challenges in wireless
communications. Accurate channel estimation has a major impact on
the whole system performance. Specifically, reliable estimate of the
channel state information (CSI) is more challenging for orthogonal
frequency division multiplexing (OFDM) systems in doubly selective
fading channels than for the slower fading channels over which OFDM
has been deployed traditionally. With the help of a basis expansion
model (BEM), a novel multivariate autoregressive (AR) process is
developed to model the time evolution of the fast fading channel.
Relying on pilot symbol aided modulation (PSAM), a novel Kalman
smoothing algorithm based on a second-order dynamic model is
exploited, where the mean square error (MSE) of the channel
estimator is near to that of the optimal Wiener filter. To further
improve the performance of channel estimation, a novel
low-complexity iterative joint channel estimation and symbol
detection procedure is developed for fast fading channels with a
small number of pilots and low pilot power to achieve the bit error
rate (BER) performance close to when the CSI is known perfectly. The
new channel estimation symbol detection technique is robust to
variations of the radio channel from the design values and
applicable to multiple modulation and coding types. By use of the
extrinsic information transfer (EXIT) chart, we investigate the
convergence behavior of the new algorithm and analyze the
modulation, pilot density, and error correction code selection for
good system performance for a given power level. The algorithms
developed in this thesis improve the performance of the whole system
requiring only low ratios of pilot to data for excellent performance
in fast fading channels.<br>Graduate
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Dinesh, Vaibhav. "Matched filter bounds for fast fading Rician channels." Thesis, 2002. http://hdl.handle.net/2429/12061.
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A new matched filter bound (MFB) for a dispersive Rician fading channel with
unrestricted normalized Doppler rate is presented. Analytical expressions are derived for BPSK
modulation.
The channel model is based on the standard linear time varying filter. The BER performance,
in general, is found to improve with an increase in the fading rate due to the inherent
diversity present within a single pulse. The shape of the transmitted pulse is shown to affect the
BER in fast fading conditions. It has been found that the specular component improves the BER at
lower fading rates; for very high fading rates, the implicit diversity effect becomes dominant in
diminishing the effect of fading.
Discrete (two and three beam) models are assumed for the dispersive channel. The error
bounds for the three-beam model are derived as a function of the inter-beam delay and correlation
parameters. In general, the delay spread was found to result in lowering the BER for both the slow
and fast fading cases when the fading in the beams is uncorrelated. In the two-beam frequency
selective case, the BER is very sensitive to the degree of beam overlap.
Finally, assuming errors in estimating the channel fading waveform, the BER for a non-ideal
receive filter is obtained. It was observed that, for the specified model, the system degradation
is higher for phase mismatches than for amplitude mismatches for a given error variance.
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Weng, Hao-Geng, and 翁浩耿. "Two-Step Channel Estimation Scheme for OFDM Systems over Fast Fading Channels." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/28422367471137400039.
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碩士<br>國立中興大學<br>電機工程學系所<br>100<br>In OFDM systems, channel state information is important is important for the receiver to recover transmitted data from channel degraded signals. In order to enable the receiver to obtain the channel information, known training symbols will be transmitted, and the number of training symbols increases with the Doppler frequency .However, the transmission of a large number of training symbols will reduce the transmission efficiency. Decision directed channel estimation (DDCE),has been proposed to reduce the number of training symbols by performing channel estimation based on the temporarily detected data, which can be obtained based on the latest channel estimate, The performance of DDCE is restricted by the turns of temporarily detected data, which may even propagate to affect succeeding data detection and channel estimation. In this thesis, we will investigate the error propagation problem of DDCE and propose methods to solve this problem. Previous researches on improving the performance of DDCE extract detected data of high reliability for channel estimation, instead of using all detection results. However the computation of probability of correctness for extracting detection results in previous researches still requires the transmission of pilot data to obtain initial channel information. We will propose a new method for extracting reliable detection results by incorporating channel prediction in the evaluation of correct detection probability. Simulation results demonstrate that at the same even detection probability, the proposed algorithm can detect a larger number of data for channel estimation, and thus has better performance than existing algorithms.
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魏鴻富. "Adaptive equalizer for fast time-varying multipath fading channels." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/22885189023963158769.
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Reader, David. "Blind maximum likelihood sequence detection over fast fading communication channels." 1996. http://arrow.unisa.edu.au:8081/1959.8/85004.
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Liu, Xiaoyu. "Optimal space time trellis code design for fast fading channels." 2007. http://etd.lib.fsu.edu/theses/available/etd-01052007-195522.
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Thesis (Ph. D.)--Florida State University, 2007.<br>Advisor: Bing W. Kwan, Florida State University, FAMU-FSU College of Engineering, Dept. of Electrical and Computer Engineering. Title and description from dissertation home page (viewed July 11, 2007). Document formatted into pages; contains ix, 81 pages. Includes bibliographical references.
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Tso, Ci-Ye, and 左啟業. "Iterative Interference Cancellation for MIMO Detection in Fast Fading Channels." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/19125163184821270554.
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碩士<br>國立清華大學<br>通訊工程研究所<br>97<br>In multiple-input-multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM)
systems, space-time block codes (STBC) and vertical Bell laboratories layered space-time
(V-BLAST) are popular techniques to get the diversity gains or multiplexing gains. STBCOFDM
system often relies on the assumption of quasistatic channels. For the time-varying
multipath channel, performance degrades seriously due to co-channel interference (CCI) and
inter-carrier interference (ICI). In this thesis, we propose an iterative interference cancellation
architecture to reduce both CCI and ICI jointly. In particular, a list successive interference
cancellation (List-SIC) algorithm is presented to obtain a candidate list to compute soft information
that is used in the CCI cancellation. Furthermore, an ICI cancellation algorithm
that uses prior List-SIC information from the preceding iteration is proposed. On the other
hand, V-BLAST OFDM also suer severe ICI in fast fading channels. Therefore, we generalize
iterative List-SIC to V-BLAST OFDM. The simulation results show that the proposed
scheme achieves near maximum likelihood (ML) error performance with lower complexity
for STBC-OFDM and V-BLAST OFDM in fast fading channels
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Lin, Chung-So, and 林仲鑠. "Investigation on the Rician Factor of Indoor Flat Fast Fading Radio Channels." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/53704735184541023302.
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碩士<br>國立交通大學<br>電信研究所<br>85<br>A newly developed hybrid model,composed of a two-
dimensional(2-D)site-specific model and a randomly scattered
model,is employed toinvestigation the Rician Factor of indoor
flat fast fading channels.In our model,the averaged scattered(
diffused)envelop,which has a significanteffect on the Rician
Distribution and is usually neglected,can be
effectivelyquantified by a ratio factor r. With a proper chosen
value of r,our model yields a reasonable prediction accuracy of
the Rician factor. It is foundthat a larger value of r
represents a stronger scattered field and yields a small value
of K,which is usually happened at the sites with heavy
surroundingclutters or in NLOS(non Line-Of-Sign)propagation
situations.
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Tan, Yin-Hung, and 談胤宏. "Differential BPSK Modulation for Cooperative Communication Systems in Fast Rayleigh Fading Channels." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/94100703683725423886.
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碩士<br>淡江大學<br>電機工程學系碩士班<br>101<br>In this thesis, we consider the amplify and forward relaying cooperative communication system employing differential binary phase shift keying modulation in fast Rayleigh fading channels. When channel gains are fast varying, it is well known that differential modulation can ease the channel estimation process and reduce the power and bandwidth overhead occurred in coherent modulation schemes. Unlike the previous work on this topic which always assumed the channel gains are the same over two adjacent symbol periods, we model the channel time selectivity exactly in our formulation and derive the optimal diversity combining weights for the amplify and forward relaying system based on the maximum likelihood criterion. Since the optimum combining rule depends on the channel gains of the relay to destination links which are usually unavailable in the context of differential modulation, we propose a suboptimal diversity combining rule which replaces the instantaneous channel gains by their second order statistics. Compared with the performance of the diversity combining rule without taking the time selectivity into account, computer simulation results show that the proposed diversity combining rule has superior performance for the amplify and forward relaying system in fast Rayleigh fading channels, especially when the relay and destination nodes have different Doppler spreads.
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Liao, Jung-Feng, and 廖榮豐. "A New Full-Diversity Blind Channel Estimation and Equalization over Fast Time-Varying ISI Fading Channels." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/03618834938194451196.
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博士<br>國立清華大學<br>電機工程學系<br>96<br>In this study, we propose a novel full-diversity combination algorithm for blind channel estimation and equalization, which takes advantage of the full-diversity gain of the multipath fading channel and executes a smoother filter operation to significantly improve the performance of the network Kalman-based blind equalizers. The proposed full-diversity blind equalizer based on the weighted Gaussian sum (WGS) technique and the network of extended Kalman filters, employs the prediction errors of network of Kalman filters to achieve the maximum likelihood (ML) solution. Therefore, the proposed algorithm can effectively estimate both the channel coefficients and the transmitted symbols over the fast time-varying inter-symbol interference (ISI) fading channels. The fast time-varying ISI fading channel is modeled by a second order autoregressive (AR(2)) process according to the Doppler frequency shift in cellular networks. Simulation results illustrate that the proposed blind equalizer based on the full-diversity combination algorithm can track the fast time-varying fading channel much more accurately than the conventional network Kalman-based blind equalizers. For symbol detection, the proposed diversity combination blind equalizers demonstrate a significant improvement compared with the conventional WGS-IMM (Interacting Multiple Model) blind equalizers in the bit error rate (BER) performance.
Besides, from the trade-off consideration between the performance and the computational complexity, the proposed modified 2-Diversity blind equalizer is a best choice for the WGS-based blind equalizer. Because the proposed 2-Diversity blind equalizer avoids the exponential growth of the computational complexity making it feasible for wireless communication systems.
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Chin-ChiYang and 楊錦記. "Iterative Frequency-Domain Equalizer in Fast Fading Channels for Single-Carrier Block Transmission." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/s5545e.
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碩士<br>國立成功大學<br>電腦與通信工程研究所<br>102<br>In fast fading channels, the single-carrier block transmission systems suffer from not only the inter-symbol interference (ISI) in the time domain, but also the virtual inter-carrier interference (virtual ICI) in the frequency domain. Therefore, equalization techniques originally designed for slow fading channels can’t be effectively applied for fast fading channels. In the literature, equalization algorithms that cope with fast fading channels include the time-domain minimum mean square error linear equalizer (MMSE-LE) and minimum mean square successive interference cancellation (MMSE-SIC). The former has a much lower complexity than the latter, at the cost of a poor bit error rate (BER) performance. In the thesis, in order to achieve a better trade-off between performance and complexity, we extend the iterative block decision feedback equalizer (IBDFE), originally designed for slow fading channels only, to fast fading channels. We design the equalizer according to the MMSE criterion. Since the equalizer coefficients require the knowledge of the correlation between the detected symbols and the transmitted symbols, methods of estimating the correlation are also investigated in the thesis.
Simulation results show that, compared with MMSE-LE, the proposed algorithm achieves a significant BER performance improvement with only a slight increase in complexity. Compared with MMSE-SIC, the proposed method has a worse BER performance in channels with a larger Doppler spread, but has a quite similar performance in channels with a smaller Doppler spread; but in both cases, the proposed algorithm has a much lower complexity.
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Chen, Ting-Wei, and 陳廷維. "Message Passing Algorithm for Space Time Block Coded MIMO Detection in Fast Fading Channels." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/73352970726853407031.
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碩士<br>國立清華大學<br>電機工程學系<br>98<br>It has been shown that space-time block coded orthogonal frequency-division multiplexing
(STBC-OFDM) system is capable to achieve full diversity in MIMO detection. The
STBC-OFDM system assumes a quasi-static block fading channel over the codeword. When
the channel is fast fading, the assumption is no longer valid. The co-channel interference
(CCI) and inter-carrier interference (ICI) in fast fading channel introduce severe performance
degradation. Several ICI cancellation methods have been proposed. However, performances
are still unsatisfactory even with considerable computation complexity. Recently, ICI selfcancellation
methods are proposed. Although these methods can mitigate ICI efficiently, the
techniques of ICI self-cancellation need to decrease the transmission rate or the bandwidth
efficiency by 50 percents. In this work, we propose an interleaved message passing algorithm
(MPA) with ICI cancellation for MIMO detection to achieve the CCI problem and reduce ICI
jointly. The MIMO channel model is represented as a factor graph, and the co-channel MPA
(CC-MPA) converges co-channel information with few inner iterations. An neighboring ICI
cancellation (NIC) uses the prior information to reduce neighboring ICI effect with outer
iteration. Interleaving channel structure can make CC-MPA obtain the received signal without
ICI earlier. Moreover, we develope a SR-controller to skip unnecessary computations.
The proposed scheme does not decrease any transmission rate or reduce the bandwidth efficiency.
Significant BER improvement is achieved through few iterations. The simulation
results show that the proposed scheme achieves near maximum likelihood sequence decoder error performance with low complexity for STBC-OFDM in fast fading channels.
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Eyceöz, Tugay. "Deterministic modeling and long range prediction of fast fading channels with applications to mobile radio systems." 2001. http://www.lib.ncsu.edu/etd/public/etd-43521431013931/etd.pdf.
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Yu-KunLiu and 劉昱琨. "Equalization Algorithms for Single-Carrier Block Transmission in Fast Fading Channels Using Poly-Diagonalization and Tree Search." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/89062161686298716782.
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碩士<br>國立成功大學<br>電腦與通信工程研究所<br>101<br>In Single-carrier block transmission (SCBT), equalizing the fast fading channel, in which channel variation within a transmitted block is not negligible, is a challenging task because many existing efficient methods targeted for slow fading channels are no longer easily applicable. In the literature, the linear equalizer (LE) usually performs poorly; on the other hand, successive interference cancellation (SIC) has a very high complexity. The QRD-M algorithm is a tree-search-based detector that achieves a better error-rate performance than LE and SIC; however, the complexity of the QR decomposition in the preprocessing stage is high. In this thesis, we focus on the tree-search-based approach. We poly-diagonalize the channel matrix in the preprocessing stage, so that, by exploiting the block format of SCBT and the structure of the poly-diagonalized channel matrix, tree search can be executed without QR decomposition. Furthermore, we investigate the detection performance of several criteria of poly-diagonalization. Simulation results show that, compared to the QRD-M algorithm, the proposed tree-search detector has slightly improved error-rate performance, at the cost of a higher complexity. In addition, the proposed algorithms outperforms the SIC with a lower complexity.
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Liang-SyunHuang and 黃亮勳. "Equalization for Single-Carrier Block Transmission in Fast-Varying Multipath Fading Channels Using Iterative Block Decision Feedback." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/03347947088553459868.
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碩士<br>國立成功大學<br>電腦與通信工程研究所<br>101<br>In doubly-selective channels, single-carrier block transmission suffers from not only inter-symbol interference (ISI) but also virtual inter-carrier interference (virtual ICI) because channel variation within a transmitted block can no longer be neglected. In this case, the detection performance deteriorates considerably if the equalizer does not account for time selectivity. In the literature, equalization algorithms that cope with time-varying channels include time-domain minimum mean squared error linear equalizer (MMSE-LE) and minimum mean squared error successive interference cancellation (MMSE-SIC). The latter has a better error-rate performance, but the former has a much lower complexity. In hopes of achieving a better trade-off between performance and complexity, we extend the low-complexity iterative block decision feedback equalizer (IBDFE), originally designed for frequency-selective channels only, to doubly-selective channels. To deal with the virtual ICI, the matrix feedback filter is adopted. We assume correct decisions to derive the equalizer coefficients; however, we feed back the actual decisions in simulations. Simulation results show that the proposed algorithm achieves a better performance than MMSE-LE with only a slight increase in complexity. Compared with MMSE-SIC, the proposed algorithm has a poorer performance, but a much lower complexity.
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Yi-ChungHuang and 黃逸中. "The Design of Frequency-Domain Iterative Block Decision Feedback Equalizer in Fast Fading Channels for Single-Carrier Block Transmission Systems." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/97724708538598627268.
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碩士<br>國立成功大學<br>電腦與通信工程研究所<br>104<br>In the thesis, we consider the problem of designing the frequency-domain iterative block decision feedback equalizer (IBDFE) in fast fading channels for the single-carrier block transmission (SCBT) system. In this situation, the IBDFE needs to deal with not only the inter-symbol interference (ISI) in the time domain, but also the virtual inter-carrier interference (virtual ICI) in the frequency domain. Since the conventional IBDFE was originally designed for slow fading channels in which no virtual ICI exists, it suffers from a considerable performance loss when directly applied in fast fading channels. Recently, the conventional IBDFE was modified for the fast fading channel. Compared to the minimum mean square error linear equalizer (MMSE-LE), it gives a much better detection performance with only a slight increase in complexity. The modified IBDFE in the literature adopts a different feedback filter (FBF) structure, but still uses the same feedforward filter (FFF) structure as the conventional IBDFE. Consequently, the virtual ICI is handled by the FBF, but not by the FFF. In this thesis, we consider a variation of the modified IBDFE by adopting a different FFF so that the FFF is capable of suppressing the virtual ICI. We study the performance-complexity tradeoff of the proposed IBDFE structure. Simulation results indicate that, in moderate-to-high signal-to-noise ratio (SNR) situations, the proposed IBDFE gives an improved detection performance over the existing IBDFEs in the literature, but at a cost of a much higher complexity.
30
Chih, Su Ch'ung, and 蘇崇智. "Error probabilities for uncoded and coded MFSK systems with diversity reception in shadowed fading channels : narrowband system and fast frequency hopped system." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/09745580222773937902.
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Yu, Tzu-Han, and 余子瀚. "FPGA Channel Generator of Fast Rayleigh Fading Channel." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/a4sn4r.
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Tsai, Wern-Fong, and 蔡文豐. "Adaptive Equalization for Fast Time-Varying Fading Channel." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/16180690768348297413.
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碩士<br>國立中正大學<br>電機工程學系<br>86<br>Both symbol-by-symbol and sequence equalization of
digital signaling on the time-varying multipath fading
channels are investigated here. Two methods for symbol-by-
symbol equalization, namely, Bayesian equalizer with
decision feedback (Bayesian DFE)and Bayesian equalizer with
recursive algorithm and one method for sequence
equalization,namely, maximum likelihood sequence
estimation(MLSE) equalizer have been considered inthis
thesis. These equalizers in conjunction with an adaptive
channel estimator consisting of a lest mean square(LMS)
estimator are considered. In this thesis, we also
consider a bi-directional adaptive equalization technique,
which uses information in the adjacent time slot in a TDMA
system and is able to estimate the location of a deep fade
within a time slot, to improve the overall digital
transmission systems performance over time varying land
mobile radio channels.
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Lee, Jie-Hao, and 李介豪. "Joint CFO and Channel Estimation over Fast-fading Channel for MIMO-OFDM Systems." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/50036397589033497335.
Full textAbstract:
碩士<br>國立交通大學<br>資訊科學與工程研究所<br>100<br>This thesis presents a cooperative carrier frequency offset (CFO) and decision-feedback tracking channel estimation scheme for MIMO-OFDM systems over time-variant frequency-selective fast-fading channels. LTE Downlink (DL) standard is targeted. It operates at 2GHz band with 10MHz bandwidth. 2 2 transceiver allocation with corresponded Space-Frequency Block Coding (SFBC) is the main consideration.
Two ITU channel models are applied to the simulation platform. One is the ITU-VehA model, and the other is the ITU-PedB model. The time-variant effect is achieved by the Rayleigh fading model.
The CFO estimation is processed in frequency domain, and evaluated by minimizing a cost function. For achieving the implementation, the estimation is decomposed into three steps. These three stages based on the effect of different scales of carrier frequency offset, using different ways to estimate.
The proposed CFO estimation can tolerate the CFO up to 25 ppm under the frequency selective channel at 1dB SNR for 2 2 MIMO-OFDM systems.
The decision-feedback tracking channel estimation contains three parts. First, the degree of channel varying will be estimated, and then the proposed channel estimation scheme is applied to the SFBC-decoded symbols in order to estimate the noisy time-variant channels. The last, a frequency domain filter is applied to each estimated noisy time-variant channel frequency response to decrease the Signal-to-Noise Ratio (SNR) requirements that this work needed.
The proposed algorithm achieves bit error rate under 120km/hr ITU-VehA model at 24dB SNR and under ITU-PedB model at 29dB for 2 2 MIMO-OFDM systems. And the memory buffer of the proposed algorithm is reduced to 10% , comparing with the conventional method.
Also this work joints these two estimation method. The estimation of fine fractional CFO is achieved by the degree of channel varying, which is in the channel estimation stage. And the residual CFO estimation and cancellation will be attained by the feedback of channel estimation result.
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Lee, Huang Chang, and 李晃昌. "Fast channel estimation methods of MIMO OFDM system over double selective fading channel." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/54094270200169824818.
Full textAbstract:
碩士<br>國立暨南國際大學<br>電機工程學系<br>92<br>Orthogonal frequency division multiplexing (OFDM) in combination with the multiple-input-multiple-output (MIMO) antennas has been proven as an efficient way to achieve high transmission capacity. Many wireless communication systems have chosen the MIMO-OFDM as transmission scheme, such as 802.11n, 802.16 and 802.20, etc. OFDM provides robust transmission in multi-path fading channel. Space-time block code (STBC) is a popular way to construct MIMO systems, since STBC can get transmission diversity gain as well as raise the channel capacity. However, these two key technologies are difficult to be applied to the high mobility transmission due to Doppler effects. The longer symbol time in OFDM systems becomes a disadvantage in fast changing channel. On the other hand, STBC requires channel response to be stable during several symbol times that make it unsuitable in mobile communication, too. The orthogonality between sub-carriers of OFDM will be destroyed if channel response changed in a symbol time, and ICI will be induced. Therefore, ICI canceller is required to maintain the orthogonality in OFDM. Precious channel response estimation has to be implemented before obtaining a perfect ICI canceller. In this thesis, a channel estimation method for OFDM systems in high mobility time varying environment is presented first. The method works well for MIMO channel, too. According to the similar idea in V-BLAST, a Tone-by-Tone signal detection method is also presented in combination with the fast channel estimation method. The Tone-by-Tone detection method can significantly improve system performance of MIMO-OFDM in time selective fading channel.
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Yeh, Che-hung, and 葉哲宏. "Joint LDPC Decoder and Channel Estimator for MIMO-OFDM Systems in Fast Fading Channel." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/77552901953575219516.
Full textAbstract:
碩士<br>國立中正大學<br>通訊工程研究所<br>95<br>Multiple input multiple output- orthogonal frequency division multiplexing (MIMO-OFDM) that is a highly efficient data transmission system does not increase any transmission power or bandwidth to improve the channel capacity. For exploiting the space, time and frequency diversity, the low density parity-check (LDPC) is used as a channel coding with a built-in interleaver. We used suboptimal soft demapping algorithms, linear minimum mean square error- soft interference cancellation (LMMSE-SIC), to reduce computational complexity caused a large constellation size and a lot of transmission antennas in the receiver.
In this thesis a jointed LDPC decoder and channel estimator algorithm was proposed. The algorithms applied soft bits information of LDPC to avoid estimate errors in low bits reliability during the demapping process. Finally, we used time domain channel correlation to enhance the accuracy of estimates.
Computer simulations under fast fading conditions and normalized Doppler frequency 0.01 show that performance of the proposed channel estimation algorithms are
0.12 dB worse than perfect channel estimation algorithms as packet error rate is 0.01.
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Lin, Kun-ming, and 林昆銘. "Joint LDPC Decoder and Frequency Domain Channel Estimator for OFDM Systems in Fast Fading Channel." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/95373205773616914700.
Full textAbstract:
碩士<br>國立中正大學<br>通訊工程研究所<br>95<br>In mobile wireless communications, the information signals are subjected to distortions caused by reflections and diffractions generated by the signals interacting with obstacles and terrain conditions. The distortions experienced by the communication signals include delay spread, attenuation in signal strength, and frequency broadening. When no line-of-sight component is available in a channel, the data transmission rate is very high, and the receiver is installed in a high-speed cruising vehicle, the channel will be ‘‘a frequency selective fast Rayleigh fading channel.’’ One of the main reasons to use orthogonal frequency-division multiplexing (OFDM) systems is to increase the robustness against frequency selective fading and narrowband interference. The equalization of the OFDM signal is usually done in the frequency domain with the inverse of the estimated channel frequency response. Therefore the channel impulse response or the channel frequency response has to be estimated.
In this thesis, an iterative receiver for a joint data-detection and channel-estimation scheme is presented for OFDM systems, which incorporates iterative decoding in the receiver. In the proposed scheme, a maximum a posteriori-based decoder and a channel estimator provide more reliable information for each other in an iterative processing. The iterative receiver under consideration employs the soft in/soft out (SISO) decoding process, which operates iteratively in conjunction with channel estimation for performing data detection and channel estimation at the same time.
Results of computer simulations under fast fading conditions and normalized Doppler frequency 0.01 show that performance of the proposed channel estimation algorithm is 1 dB better than no tracking channel estimation algorithms as packet error rate is 0.01.
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Wu, Kun-Zhan, and 吳昆展. "Adaptive MIMO-GFDM receiver over fast fading channel for next generation communications." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/10673194779521847665.
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Hsiao, Po-Hsiu, and 蕭博修. "Fast Fading MIMO Broadcast Channel with Rate Limited Feedback: Degrees of Freedom Analysis." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/yqbw8y.
Full textAbstract:
碩士<br>國立臺灣大學<br>電信工程學研究所<br>104<br>In this thesis, we study MIMO broadcast channel with rate limited feedback. For fast fading MIMO broadcast channel, it is well known that channel state information at receiver (CSIR) is not sufficient to provide significant increase of the throughput, namely, degrees of freedom gain. The transmitter needs the channel state information to carry out interference mitigation techniques such as beamforming to improve capacity. Typically, channel state state information at transmitter (CSIT) is obtained from feedback. Since rate-limited feedback creates delay and inaccuracy in CSIT, it is of fundamental interest to understand how such delayed imperfect CSIT can improve system performance.
First, we consider independent and identically distributed (i.i.d.) fast fading channel. A scheme based on network coding ideas, where the receivers feedback quantized channel gains through rate-limited feedback links and the transmitter uses these channel gains to reconstruct interference and sends the combined interference to create network coding opportunities. However, the feedback requirement of this scheme grows very large as the number of users increases, and hence it does not utilize feedback efficiently. We propose a novel scheme in which the receivers feedback quantized interference through rate-limited feedback links instead of channel gains. This method can utilize the feedback resource more efficiently. We show that our proposed scheme and feedback method can provide more degrees of freedom gain than baseline scheme.
After the analysis in i.i.d. fast fading channel, we extend our scheme to temporally correlated channel. Transmitter can estimate current CSIT from the feedback. We propose our transmission scheme which is suitable for our feedback-interference method. Our proposed feedback method and transmission scheme still has better performance than the best-known schemes in the literature.
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King-Tai, Yang. "Space-Time Processing for Mobile Communications with Multipath Fast Fading and Co-Channel Interference." 1997. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0009-0112200611363653.
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Hsiao, Yao-Shan, and 蕭樂山. "Fast Fading MIMO Broadcast Channel with Rate Limited Feedback and Impact of Local Channel State Information:Degrees of freedom analysis." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/28p855.
Full textAbstract:
碩士<br>國立臺灣大學<br>電信工程學研究所<br>105<br>In this thesis, we cope with some extra cost when we want to implement an optimal DoF-achievable scheme of MISO broadcast channel through utilizing delayed channel state information (DCSIT).
The seminal work by Maddah-Ali and Tse shows that DCSIT can increase the sum of degrees of freedom (DoF) in fast-fading MIMO BC regime. We call the optimal scheme ``MAT scheme".
The first cost of disseminating CSIR is investigated and we propose a model to capture the cost.
In a family of linear schemes, we find DCSIT is not useful to improve DoF region in a homogeneous DCSIT setting.
However, DCSIT is still useful in heterogeneous CSIT setting to improve DoF region while considering the cost.
The second cost is the CSI feedback.
We propose optimal strategies of two methods: feedback interference and feedback channel coefficients.
We characterize the mathematical optimization problem and solution. Moreover, we prove that the feedback-interference method outperforms the feedback-channel-coefficient method, which is a traditional method of feedback.
The feedback-interference method can provide more DoF gain.
Finally, we consider a two-cell interference channel and find a method which utilizes the channel diversity to reduce the exchanging quantity between two base station while implementing MAT scheme.
This method can help the base stations cooperate and use less resource to achieve the optimal sum of DoF of the broadcast channel.
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Liao, Wei-Ji, and 廖偉吉. "Robust Fast Time-Varying Multipath Fading Channel Estimation and Equalization for MIMO-OFDM System via Fuzzy Filter Method." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/69191154091058372803.
Full textAbstract:
碩士<br>國立清華大學<br>電機工程學系<br>98<br>Channel estimation is an important issue for wireless communication system.
A Channel estimation scheme using Takagi-Sugeno (T-S) fuzzy-based Kalman filter under the time-varying velocity of mobile station in a multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) system is proposed in this paper.
We consider the orthogonal space time block coding (OSTBC) scheme of MIMO system where the mobile radio channel is modeled as an autoregressive (AR) random process.
The parameters of the AR process and the channel gain are simultaneously estimated by the proposed T-S fuzzy-based Kalman filter to achieve robust nonlinear parameter estimation and prediction by interpolating several linear parameter systems at different mobile speeds to approximate the nonlinear parameter systems in MIMO-OFDM communication.
It is useful for the decision-directed channel tracking design, especially in fast fading channel due to time-varying velocity of mobile station.
The inherent delay problem of decision-directed scheme can also be compensated by a fuzzy Kalman-based channel prediction method.
Further, the robust MMSE equalization design can be achieved by the consideration of channel prediction error to improve the performance of symbol detection.
To confirm the performance of proposed method, several simulation results are given in comparison with other methods.
With consideration of time-varying velocity of the mobile station communicated in the MIMO-OFDM system, the enhanced equalizer based on the T-S fuzzy-based Kalman filter performs better than those based on the conventional channel estimators in symbol error rate.
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Su, Chien-Li, and 蘇建吏. "On the Secrecy Rate Region of a Fast Fading Multiple-Antenna Gaussian Broadcast Channel with Confidential Messages and Partial CSIT." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/84496919642921492310.
Full textAbstract:
碩士<br>國立臺灣大學<br>電信工程學研究所<br>100<br>In this thesis we consider the secure transmission over the fast fading multiple antenna Gaussian broadcast channel with confidential messages (FMGBC-CM), where a multiple-antenna transmitter sends independent confidential messages to two users with informa-tion theoretic secrecy and only the statistics of the receivers’ channel state information are
known at the transmitter. We first use the same marginal property of the FMGBC-CM to classify the non-trivial cases, i.e., both the two users have nonzero rates. We then derive the achievable rate region for the FMGBC-CM by solving the channel input covariance matrices and the inflation factor. Due to the complicated rate region formulae, we also resort
to low SNR analysis to investigate the characteristics of the channel. Finally, the numerical examples show that under the information-theoretic secrecy requirement both users can
achieve positive rates simultaneously.