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 29 for “"frequency selective fading"”.
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Advanced receivers for space-time block-coded single-carrier transmissions over frequency-selective fading channels
… to combat the detrimental effects of channel fading. In addition to STBC, high-order modulation schemes will be used in future wireless communication systems aiming to provide ubiquitous-broadband wireless access. Hence, advanced receiver schemes are necessary to achieve high performance. In …
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Low-Complexity Iterative Receiver Design for Multi-Carrier Faster-Than-Nyquist Signaling Over Frequency-Selective Fading Channel
… minimum spacing of orthogonal subcarriers in the frequency domain for remarkably improving the spectral efficiency, which still occupies the same frequency bandwidth. However, time-frequency compression introduces severe inter-symbol interference and inter-carrier interference simultaneously, …
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An investigation into the performance of a power-of-two coefficient transversal equalizer in a 34Mbit/s QPSK digital radio during frequency-selective fading conditions
… differing length, results in the phenomenon of frequency-selective fading. This phenomenon manifests as a notch in the received spectrum and causes a severe degradation in the performance of a digital radio system. As the total power in the received bandwidth may be unaffected, the Automatic …
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Bit error simulation of FSK, BPSK, and pi/4 DQPSK in flat and frequency-selective fading mobile radio channels using two-ray and measurement- based impulse response models
… performance of digital mobile radio systems in fading channels. The simulation tool generates average bit error rate (BER) and bit-by-bit error patterns with user-specified parameters. The simulation tool can simulate various communication system parameters (i.e. modulation scheme, data rate, …
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I/Q imbalance mitigation for space-time block coded communication systems
… by exploiting the spatial diversity in fading channels. However, due to component imperfections, the in-phase/quadrature (I/Q) imbalance caused by the non-ideal matching between the relative amplitudes and phases of the I and Q branches always exists in the practical implementation of …
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Frequency Response of an Agricultural Fence and the Implications for Data Transmission
… has been conducted into determining the optimum frequency bands to transmit in to give optimum performance. We propose that the fence spectrum be split into three frequency bands. A Fence Pulse Guard Band which extends from DC to 10 kHz, a Low Frequency Channel which extends from 10 kHz to 250 …
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Channel modeling and resource allocation in OFDM systems
… plagued by multipath propagation, which causes frequency-selective fading in broadband signals. 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 …
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Reducing Multiple Access Interference in Broadband Multi-User Wireless Networks
… by means of spreading codes. However, in frequency selective fading channels, orthogonality among users can be destroyed leading to MAI. MAI represents the main obstacle to support large number of users in multi-user wireless systems. Consequently, MAI reduction becomes a main challenge …
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Hybrid Orthogonal Code Sequences for High-Density Synchronous CDMA Systems
… orthogonal m-sequence under Rayleigh flat and frequency selective fading channel conditions while having a significantly higher capacity than those orthogonal code sequences. The proposed HOVLS code sequence could support 134 different cells which is more than twice than that of orthogonal Gold …
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An analysis of a broadband multicarrier CDMA cellular communications system
… within the littoral environment will require fading resistant, high data rate, non-exploitable communications. The large volumes of video and data information, i.e. Internet access, video teleconferencing and data transfer, required to support the war fighter within a Joint Task Force demands …
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Performance Study of OFDM over Fading Channels for Wireless Communications
<p>Orthogonal Frequency Division Multiplexing (OFDM) is a very efficient multicarrier technique. OFDM is used more and more in recent wideband digital communications. It has numerous advantages such as the ability to handle severe channel conditions, efficient spectral usage, reduced inter symbol …
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Digital Transmission by Hermite N-Dimensional Antipodal Scheme
… over a radio link using either amplitude or frequency modulation. The bandwidth efficiency of the amplitude Hermite method is found to be as good as filtered BPSK in practice, while the bit error rates for both modulations are identical. Hermite Keying (HK), the FM modulation version of the …
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Antenna Array Systems: Propagation and Performance
… derived for space-time processing structures in frequency selective fading channels. The hardware and software of the MPRG Antenna Array Testbed (MAAT) is described. A literature review of previous antenna array propagation measurements is given. Antenna array measurement results obtained with …
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Novel multiuser detection and multi-rate schemes for multi-carrier CDMA
… systems. MC-CDMA is a hybrid of orthogonal frequency division multiplexing (OFDM) and code division multiple access (CDMA). The most salient feature of MC-CDMA is that the rate of transmission is not limited by the wireless channel's frequency-selective fading effects caused by multipath …
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Iterative Techniques Based on Energy Spreading Transform for Wireless Communications
… algorithms for communication systems over fading channels. They include channel equalization to combat intersymbol interference (ISI) and multiple input multiple output (MIMO) signal detection to deal with multiple access interference (MAI) from other transmit antennas. As the demand for …
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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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Frequency Domain Independent Component Analysis Applied To Wireless Communications Over Frequency-selective Channels
In wireless communications, frequency-selective fading is a major source of impairment for wireless communications. In this research, a novel Frequency-Domain Independent Component Analysis (ICA-F) approach is proposed to blindly separate and deconvolve signals traveling through …
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Null power reallocation for data rate improvement in a wireless multicarrier system
… by the IEEE 802.11 standards do not adapt to frequency-selective fading but simply choose a constant data modulation scheme and transmit power level for all sub carriers in the available signal bandwidth. Although these implementations maintain acceptable performance when channel conditions …
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Optimal Detection with Imperfect Channel Estimation for Wireless Communications
… systems transmitting data through unknown fading channels, traditional detection techniques are based on channel estimation (e.g., by using pilot signals), and then treating the estimates as perfect in a minimum distance detector. In this thesis, we derive and investigate an optimal …
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Optimum linear single user detection in direct-sequence spread-spectrum multiple access systems
… spread spectrum</i> (DS-SS) offers resistance to frequency selective fading and graceful degradation of the performance as the number of users increases. Orthogonality of the signals in time-division multiple access and frequency-division multiple access is inherent from the nature of the multiple …
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