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 137 for “"Orthogonal Frequency Division Multiplexing (OFDM)"”.
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A comparison of timing methods in orthogonal frequency division multiplexing (OFDM) systems
Orthogonal frequency division multiplexing (OFDM) is being used by wireless local area network (WLAN) standards, such as IEEE 802.11a, and wireless metropolitan area network (MAN) standards, such as IEEE 802.16a. OFDM is a very efficient communications scheme for wireless ADHOC networks. However, …
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A Comparison Between Synchronous CDMA and Orthogonal Frequency Division Multiplexing (OFDM) for Fixed Broadband Wireless Access
… fixed broadband wireless access are Time Division Synchronous Code Division Multiple Access (TD-SCDMA) and Orthogonal Frequency Division Multiplexing (OFDM). This thesis aims to provide a preliminary study on using TD-SCDMA and OFDM for broadband wireless systems. Currently, there is not …
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Peak power reduction in orthogonal frequency division multiplexing transmitters
Orthogonal Frequency Division Multiplexing (OFDM) is a digital transmission method developed to meet the increasing demand for higher data rates in communications which can be used in both wired and wireless environments. This thesis describes the issue of the Peak to Average Power Ratio (PAPR) in …
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Ofdm system cyclic prefix characteristic analaysis for wimax technology
… for Microwave Access (WIMAX) system based on Orthogonal Frequency Division Multiplexing (OFDM) with different adaptive modulation techniques is currently the topic of discussion.WIMAX is the next generation of broadband wireless technology which offers a greater range and bandwidth compared to …
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Inter-carrier interference mitigation for underwater acoustic communications
… channel has a long delay spread, which makes orthogonal frequency division multiplexing (OFDM) an attractive communication scheme. However, the underwater acoustic channel is highly dynamic, which has the potential to introduce significant inter-carrier interference (ICI). This thesis explores …
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Pilot patterns and power loading in NC-OFDM cognitive radios
… radios is widely proposed through the use of Orthogonal Frequency Division Multiplexing (OFDM) modulation. In the special case of cognitive radios however, the OFDM modulation scheme cannot simply be implemented without modification due to the huge change in the basic laws of the transmission …
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Quantitative Interference and Capacity Analysis of Broadband Multi-Hop Relaying Networks
… analyzes the Bit Error Rate (BER) performance of Orthogonal Frequency Division Multiplexing (OFDM) systems in mobile multi-hop relaying channels. We consider the uplink scenario and quantify the effects of mobile channel impairments such as Doppler Shift due to user mobility per hop, high-power …
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Algorithms for channel impairment mitigation in broadband wireless communications
… and recent broadband wireless systems such as frequency hopping (FH) and orthogonal frequency division multiplexing (OFDM) ones, respectively. In particular, a novel maximum likelihood (ML)-based scheme is proposed for joint interference rejection and symbol detection in FH systems. For …
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Performance of orthogonal frequency division multiplexing in a high noise, low signal-to-noise ratio environment with co-channel interference
Orthogonal Frequency Division Multiplexing (OFDM) is fast becoming the signal modulation technique of choice for many commercial and military wireless applications. Its resilience to cochannel interference and bandwidth efficiency make it ideal for many different applications. With its increasing …
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Spread OFDM via carrier interferometry spreading codes: performance, throughput, and PAPR enhancement
Orthogonal Frequency Division Multiplexing (OFDM) has been an important technique in wireless communication architectures since the 1970's and 1980's. OFDM is now the protocol in the IEEE 802.11a and IEEE 802.1 lg Wireless Local Area Networks (WLANs) standards, as well as the IEEE 802.16 Fixed …
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A new data rotation syncrhonization scheme for CP based OFDM systems
… rotation scheme for symbol timing and carrier frequency offset (CFO) estimation of orthogonal frequency-division multiplexing (OFDM) systems. We first analyze Beeka??s cyclic prefix (CP) based joint ML estimator [2] and find that its performance can be improved when the average energy of the CP …
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PAPR reduction in OFDM communications with generalized discrete Fourier transform
… to design a wide selection of constant modulus orthogonal code sets, based on the desired performance metrics mimicking the engineering specs of interest. One of the main drawbacks of Orthogonal Frequency Division Multiplexing (OFDM) systems is the high Peak to Average Power Ratio (PAPR) value …
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Physical layer DSP design of a wireless gigabit/s indoor LAN
… National Information Infrastructure (U-NII) frequency band, and proposes a multipath-resistant transceiver design based on Orthogonal Frequency Division Multiplexing (OFDM) with adaptive multilevel Quadrature Amplitude Modulation (M-QAM). The proposed network design allows two-way …
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Generalized discrete Fourier transform with non-linear phase : theory and design
… including discrete multi-tone (DMT), orthogonal frequency division multiplexing (OFDM) and code division multiple access (CDMA) communications systems. Among these popular transforms, DFT is a linear phase transform and widely used in multicarrier communications due to its performance …
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Multicarrier Wireless Systems with Adaptive Decision Combining
Multicarrier Orthogonal Frequency Division Multiplexing (OFDM) systems with decision combining are considered in this thesis. It is shown that such systems can provide enhanced bit error rates. However, this occurs at the cost of data throughput of the system. The typical system considered …
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OFDM Channel Estimation with Artificial Neural Networks
<p>The use 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 …
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Implementation of Orthogonal Frequency Division Multiplexing with FPGA
… or IEEE802.11 wireless local area network. Orthogonal frequency division multiplexing (OFDM) has been widely used in IEEE802.11 wireless local area network and fourth generation network. This paper will focus on the design and implementation of an Orthogonal Frequency Division Multiplexing …
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Evaluation performance of OFDM system using the selected mapping technique for WIMAX technology
Orthogonal Frequency Division Multiplexing (OFDM) is a promising technique used in the wireless broadband communication systems these days. It is a form of multicarrier modulation technique with high spectral efficiency, robustness to channel fading, immunity to impulse interference, uniform …
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Peak to average power ratio reduction in the orthogonal frequency division multiplexing system using partial transmit sequence
Orthogonal frequency division multiplexing (OFDM) has been becoming more popular modulation technique in the high-speed wireless communication system. It is used especially in Long Term Evaluation technique (LTE) which depended from the fourth-generation (4G) of wireless communication system. OFDM …
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Analysis of Wavelet Based Alternatives for OFDM
… is to analyze wavelet based alternatives 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 …
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