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 251 for “"OFDM"”.
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OFDM turbo transceivers
… of Orthogonal Frequency Division Multiplexing (OFDM). More explicitly, powerful turbo transceivers invoking Sphere Packing (SP) modulation are designed using EXtrinsic Information Transfer (EXIT) charts for both single-user and multi-user transmission. In order to provide an attractive suite of …
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Simulation of Adaptive Array Algorithms for OFDM and Adaptive Vector OFDM Systems
… Orthogonal frequency division multiplexing (OFDM) is well-known to be effective against multipath distortion. It is a multicarrier communication scheme, in which the bandwidth of the channel is divided into subcarriers and data symbols are modulated and transmitted on each subcarrier …
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Adaptive, Turbo-coded OFDM
… as orthogonal frequency division multiplexing (OFDM) suitable for high data rate transmission with forward error correction (FEC) methods over wireless channels. In this thesis, we enhance the system throughput of a working OFDM system by adding turbo coding and adaptive modulation (AD). …
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OFDM for Underwater Acoustic Communication
… Orthogonal Frequency Division Multiplexing (OFDM) signals, but will in principle work for other kinds of wideband signals also. The presented results — using MATLAB based simulations, and over-the-air experiments performed in such a way as to introduce the Doppler effect in the received …
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Outphase power amplifiers in OFDM systems
A trade-off between linearity and efficiency exists in conventional power amplifiers. The outphase amplifying concept overcomes this trade-off by enabling the use of high efficiency, non-linear power amplifiers for linear amplification. An amplitude modulated signal is first decomposed into two …
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Secure OFDM System Design for Wireless Communications
… for secure transmitter-receiver interaction in OFDM systems.
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Radio Resource Allocation in Wireless OFDM Systems
… radio resource allocation problems in wireless OFDM systems using both centralized optimization and game theoretic approaches. In our work we consider only integer numbers for bit-loading for practical purpose. The subcarrier, bit and power allocation (SBPA) problem in single-cell and multi-cell …
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Analysis of Wavelet Based Alternatives for OFDM
… for orthogonal frequency division multiplexing (OFDM) and find whether a better system performance is achieved when compared to the discrete Fourier transform (DFT)-based OFDM. We analyze DFT, discrete wavelet transform (DWT), and dual tree complex wavelet transform (DT-CWT) based systems in an …
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OFDM Channel Estimation with Artificial Neural Networks
… of orthogonal frequency-division multiplexing (OFDM) by wireless standards is often preferred due to its high spectral efficiency and ease of implementation. However, data transmission via OFDM still suffers when passing through a noisy channel. In order to maximize the abilities of OFDM, …
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Nonlinear Doppler Warp Correction for Acoustic OFDM
… uses Orthogonal Frequency Division Multiplexing (OFDM) to encode the data symbols, but the Doppler Correction technique will in principle work for other kinds of wideband signals as well. The results, which include MATLAB based simulations and over-the-air experiments, show that performance …
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Channel Estimation for OFDM Systems With Transmitter Diversity
Orthogonal Frequency-Division Multiplexing (OFDM) is now regarded as a feasible alternative to the conventional single carrier modulation techniques for high data rate communication systems, mainly because of its inherent equalisation simplicity. Transmitter diversity can effectively combat …
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Adaptive OFDM Radar for Target Detection and Tracking
… orthogonal frequency division multiplexing: OFDM) radar signal. The frequency diversity of the OFDM signal improves the sensing performance since the scattering centers of a target resonate variably at different frequencies. In addition, being a wideband signal, OFDM improves the range …
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Resilient Waveform Design for OFDM-MIMO Communication Systems
… the Orthogonal Frequency Division Multiplexing (OFDM) and the Multiple Input Multiple Output (MIMO) systems; the `de-facto' air-interface of most wireless broadband standards including LTE and WiMAX. The major contributions of this dissertation are: 1) developing jamming taxonomy, 2) proposing …
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Phase noise effects on OFDM : analysis and mitigation
Orthogonal frequency division multiplexing (OFDM) is a promising technique which has high spectrum efficiency and the robustness against channel frequency selectivity. One drawback of OFDM is its sensitivity to phase noise. It has been shown that even small phase noise leads to significant …
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Channel modeling and resource allocation in OFDM systems
… Orthogonal Frequency-Division Multiplexing (OFDM) is a modulation scheme specifically designed to facilitate high-speed data transmission over frequency-selective fading channels. The problem of channel modeling in the frequency domain is first investigated for the wideband and ultra wideband …
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Relay Diversity Techniques for OFDM and MC-CDMA
… relay cyclic delay diversity (RCDD) for OFDM and MC-CDMA<br/>systems. The performance analysis of the wireless relay networks under<br/>dierent protocols and fading channels are investigated. We derived<br/>the formulas for the symbol error rate (SER) of the investigated<br/>schemes in …
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Waveform design and processing techniques in OFDM radar
… One such direction is the recently investigated OFDM radar, which uses OFDM waveforms instead of the classic linear frequency mod- ulated waveforms. Being a wideband signal, the OFDM symbol offers spectral efficiency along with improved range resolution, two enticing characteristics for radar. …
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