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 21 for “"Adaptive Modulation"”.
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Channel Prediction for Adaptive Modulation in Wireless Communications
This thesis examines the benefits of using adaptive modulation and coding in terms of spectral efficiency and probability of bit error. Specifically, we examine the performance enhancement made possible by using linear prediction along with channel estimation in conjunction with adaptive …
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Stochastic optimization algorithms for adaptive modulation in software defined radio
Adaptive modulation has been actively researched as a means to increase spectral efficiency of wireless communications systems. In general, analytic closed form models have been derived for the performance of the communications system as a function of the control parameters. However, in systems …
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On the Impact of Channel and Channel Quality Estimation on Adaptive Modulation
… wireless systems are designed by choosing a modulation scheme to meet worst case conditions and thus rely on power control to adapt to changing channel conditions. Adaptive modulation, however, exploits these channel variations to improve the spectral efficiency of wireless communications by …
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Real-time sub-carrier Adaptive Modulation and Coding in wideband Orthogonal Frequency Division Multiplexing wireless systems
… at a low additional complexity. Sub-carrier Adaptive Modulation and Coding (AMC) exploits the high frequency diversity in wideband Orthogonal Frequency Division Multiplexing (OFDM) channels to obtain higher data rates. While prior work has discussed the value of sub-carrier AMC from a …
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An adaptive Orthogonaly Division Multiplexing baseband modem for wideband wireless communication
… Multiplexing base-band modem with Frequency Adaptive Modulation protocol for a wideband indoor wireless channel. The baseband modem is implemented on a Field Programmable Gate Array and uses 294,939 2-input NAND gates with a clock frequency of 128 MHz. The Frequency Adaptive Modulation …
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Ofdm system cyclic prefix characteristic analaysis for wimax technology
… 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 the other available broadband wireless access technologies such …
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A Study of the Effects of Scintillation on Digital Satellite Communication Systems
… results show that the higher the order of the modulation that is being used, the larger is the effect of scintillation on the bit error rate performance of the link.<br/><br/>In the third part of the thesis, fade mitigation techniques to overcome the effects of scintillation fading are …
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Adaptive, Turbo-coded OFDM
… a working OFDM system by adding turbo coding and adaptive modulation (AD). Simulation is done over a time varying, frequency selective Rayleigh fading channel. The temporal variations in the simulated wireless channel are due to the presence of Doppler, a sign of relative motion between …
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Cross-Layer Capacity Optimization In OFDMA Systems: WiMAX And LTE
… qos requirements as constraints is presented. An adaptive modulation and coding (amc)-based cross-layer scheme has also been proposed in this thesis by adopting an amc scheme together with the cross-layer scheme to realize a more practical and viable resource allocation. The optimization does not …
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Link adaption with limited feedback for future wireless networks
… signal-to-noise ratio so that scheduling and adaptive modulation and coding scheme (MCS) can be performed to optimise the system performance. The received SNR is measured by the mobile users in the downlink transmission and converted to channel state information (CSI), which is sent via …
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Value function approximation architectures for neuro-dynamic programming
… the network utility maximization (NUM) and adaptive modulation (AM) are combined to balance the network performance and transmission power. In these applications, we show how to model the real problems by using the MDP model with reasonable assumptions and necessary approximations. …
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Optimizing resource allocation in large communications satellite constellations
… phased array antennas, on-board processing, and adaptive modulation and coding schemes. Several approaches have been proposed to deal with the complexity of the added flexibilities at the spacecraft level. Nevertheless, how to address the flexibilities at the constellation level, critical to …
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Different Multiple Input Multiple Output Systems
… and SVD-based MIMO systems. The application of adaptive modulation in the SVD-based system and the introduction of a new effcient decoding method for the VBLAST system are also included. Simulation results are reported with comments and conclusions.
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Performance evaluation of cross-layer energy-efficient transmit antenna selection for spatial multiplexing systems
… is then introduced and analyzed. Additionally, adaptive modulation is incorporated into the proposed cross-layer scheme to enhance system performance. Cross-layer energyefficient transmit antenna selection for underlay CR MIMO systems, where interference constraints now come into play, is then …
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Cross-Layer Optimization: System Design and Simulation Methodologies
… in wireless communication technologies, such as adaptive modulation and adaptive antenna algorithms, demand a cross layer perspective to this problem in order to provide a sufficient level of fidelity. However, a full simulation of both layers often results in excessively burdensome simulation …
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Link Adaptation for Mitigating Earth-to-Space Propagation Effects on the NASA SCaN Testbed
… high link margins and static, lower rate, modulation formats. This thesis first characterizes the propagation environment experienced by a software-defined radio on the NASA SCaN Testbed through a full link-budget analysis. Then, the following chapters propose, design, and model a link …
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Perspectives of Jamming, Mitigation and Pattern Adaptation of OFDM Pilot Signals for the Evolution of Wireless Networks
… jamming strategy leverages the dependence of the adaptive modulation and coding (AMC) schemes on the CQI estimate in LTE. Lastly, we investigate the idea of pilot pattern adaptation for SISO- and spatial multiplexing MIMO-OFDM systems. We present a generic heuristic algorithm to predict the …
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Efficient radio resource management for future generation heterogeneous wireless networks
… Lastly, a joint radio resource allocation with adaptive modulation and coding scheme is proposed to minimize the total transmit power across femtocells by considering the location and the service requirements of each user in the network. The performance of the proposed algorithms is evaluated by …
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Channel modeling and resource allocation in OFDM systems
… 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 wireless …
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Effects on Campostoma oligolepis Digestive Morphology and Gut Microbiota Composition across a Gradient of Urbanization
<p><em>Campostoma oligolepis</em>, the Largescale Stoneroller, is a species of minnow native to northwest Georgia. This study investigated the impacts of urbanization on gut length and gut microbiota community composition in <em>C. oligolepis</em> from four small watersheds within the Etowah River …
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