Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 22 for “"multipath channel"”.
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Asynchronous bi-directional relay-assisted communication networks
… delays. Such a network can be viewed as a multipath channel which can cause inter-symbol-interference (ISI) in the signals received by the two transceivers. Hence, we model such a communication scheme as a frequency selective multipath channel which produces ISI at the two transceivers, …
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Techniques to Improve the Efficiency of Data Transmission in Cable Networks
… of the thesis is a technique to estimate the multipath channel for DOCSIS 3.1 cable networks. DOCSIS 3.1 is markedly different from prior generations of CATV networks in that OFDM/OFDMA is employed to create a spectrally-efficient signal. In order to effectively demodulate such a signal, it is …
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Hybrid Channel Coding for Error-Sensitive Class on DS-CDMA Air Interface
… system is provided on uplink and downlink. For a multipath channel environment, modeling techniques for AWGN and Rayleigh fading are illustrated. Comparisons are made concerning the performance of CDMA systems with hybrid data rates. The thesis proposes a technique for hybrid channel coding for …
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A hybrid-structure offset-QAM filter-bank multi-carrier MIMO system
… frequency domain equalization (FDE) to equalize multipath channel effects at the receiver, there is a computational complexity overhead when using PPN. A novel hybrid-structure OQAM/FBMC MIMO space-frequency block coding (SFBC) system is proposed, to achieve the lowest possible overall complexity …
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Sistemas de transmissão multiportadora aplicados em um canal acústico submarino na presença de efeito doppler
… We investigate system performance in a multipath channel and in the presence of Doppler effect. The use of OFDM technique allows high transmission rate, increasing the amount of information allocated in each transmitted block. On the other hand, the SCFDMA technique, besides allowing a …
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Iterative detection for overloaded OFDMA with spatial diversity
… to mitigate the effects of the wireless multipath channel but are limited in system capacity to available bandwidth. This shortcoming can be worked around through the process of "overloading," where users are additionally multiplexed in the spatial domain to each frequency resource. To …
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The impact of Rayleigh fading channel effects on the RF-DNA fingerprinting process
… the coefficients of an indoor Rayleigh fading channel. The performance of the Nelder-Mead estimator is compared to the Least Square estimator and is assessed with degrading signal-to-noise ratio. The Rayleigh channel coefficients set estimated by the Nelder-Mead estimator is used to remove the …
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Algorithms for indoor localization based on IEEE 802.15.4-2011 UWB and inertial sensors
… arrival measurements for ranging applications. A multipath propagation controlling technique is synthesized which considers the relationship between transmit power, transmission range and signal-to-noise ratio. The methodology includes a novel bilateral transmitter output power control algorithm …
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Analysis of CDMA cellular radio systems employing adaptive antennas
… expressions are further extended to accommodate multipath radio channels when omni-directional antennas, fixed directional antennas, or adaptive antennas are applied at either end of the link. This dissertation also develops a channel model which may be used to simulate the direction-of-arrival …
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Channel Estimation for OFDM Systems With Transmitter Diversity
… Transmitter diversity can effectively combat multipath channel impairments due to the dispersive wireless channel that can cause deep fades in some subchannels. The combination of the two techniques, OFDM and transmitter diversity, can further enhance the data rates in a frequency-selective …
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Channel estimation and signal enhancement for DS-CDMA systems
… space-time (S-T) transceiver design, and S-T channel parameter estimation for direct-sequence code-division multiple-access (DS-CDMA) systems. Using the Bayesian framework, various linear and simplified nonlinear multiuser detectors are proposed, and their performances are analyzed. The …
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Channel estimation for Gigabit Multi-user MIMO-OFDM Systems
The fundamental detection problem in fading channels involves the correct estimation of transmitted symbols at the receiver in the presence of Additive White Gaussian Noise (AWGN). Detection can be considered when the receiver is assumed not to know the channel (non-coherent detection), or …
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Radio Channel Measurements and Modeling for Smart Antenna Array Systems Using a Software Radio Receiver
… and software-defined radio development. A four-channel, wideband, software-defined receiver was developed to serve as a test bed for wideband measurements and antenna array experiments. This receiver was used to perform vector channel measurements in terrestrial and air-to-ground environments …
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A Ray-Based Investigation of the Statistical Characteristics and Efficient Representation of Multi-Antenna Communication Channels
… methods predict the behavior of wireless channels using a model of the propagation environment and are a low-cost alternative to direct measurements. We use ray tracing simulations to validate the statistical time and angle of arrival characteristics of an indoor multipath channel and …
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Radio-Location Techniques for Localization and Monitoring Applications. A study of localisation techniques, using OFDM system under adverse channel conditions and radio frequency identification for object identification and movement tracking
… to improve angle-of-arrival estimation in a multipath channel with high levels of additive white Gaussian noise. A new methodology is interpreted over the multi carrier modulation scheme in which the simulation results of the estimated channel improves the performance of OFDM signal by …
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Ultra-wideband technology for short-range wireless communication
… over additive white Gaussian noise (AWGN) and multipath channels. Starting from the known capacity of M-ary modulated signals, the computation of UWB capacity over the AWGN channel takes into account UWB specific constraints. The constraints are the power spectrum density limitation under …
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Turbo space-time coded modulation : principle and performance analysis
… however, cannot fully address the problem of multipath fading channel. Recent advances in information theory have revolutionized the traditional view of multipath channel as an impairment. New results show that high gains in capacity can be achieved through the use of multiple antennas at the …
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Underwater communication via particle velocity channels : principles, channel models, and system design
… and equalization in underwater particle velocity channels using acoustic vector sensors was developed. System equations for such a receiver were derived and channel equalization using these sensors was formulated. A multiuser system using vector sensors and space time block codes was also …
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Orthogonal Frequency Division Multiplexing Modelling
… be investigated using an ideal communication channel and replicated in a multipath fading channel. Using OFDM modulation techniques, a multipath channel was investigated for realistic simulations. In MATLAB, a picture was used as the input signal to identify the OFDM modulation method with the …
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Algorithms and Architectures for UWB Receiver Design
… UWB signals (e.g., improved timing resolution or multipath fading mitigation). However, most of the applications have focused on indoor environments where the UWB channel is characterized by tens to hundreds of resolvable multipath components. Such environments introduce tremendous complexity …
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