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 32 for “"Modulation formats"”.
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Numerical modelling of advanced modulation formats and WDM transmission
… of the application of advanced modelling formats in high-speed fibre lightwave systems. The first part of this work focuses on numerical optimisation of dense wavelength division multiplexing (DWDM) system design. We employ advanced spectral domain filtering techniques and carrier pulse …
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Fast all-digital carrier synchronization techniques for linear modulation formats
… based on oversampling, suitable for linear modulation schemes ( M -ary phaseshift-keying ( M -PSK) and M -ary quadrature amplitude modulation ( M -QAM)). Carrier synchronization is studied because, in passband communications, carrier phase and frequency offsets, due to modem oscillator …
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High speed optical communication systems: From modulation formats to radically new fibres
… [1,2]. It is in this context that the work on modulation formats, contained in Chapter 3 of this thesis, was undertaken. The work investigates the proposed energy-efficient four-dimensional modulation formats. The work begins by studying a new visualisation technique for four dimensional …
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Improvement of Fiber Optic System Performance by Synchronous Phase Modulation and Filtering at the Transmitter
… of a novel variant of a return-to-zero (RZ) modulation format, based on square-wave phase modulation and filtering of a continuous-wave (CW) signal, is investigated and compared with various modulation formats considered in the literature. We call this modulation format continuous-wave …
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Digital Signal Processing for Front-end Non-idealities in Coherent Optical OFDM system
… in CO-OFDM system with non-constant amplitude modulation formats. Thirdly, we propose a decision-aided joint compensation method for Tx IQ mismatch and channel distortion. Lastly, we analytically derive new LLR with linear phase noise term for LDPC coded OFDM system with different modulation …
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Optical communications with a Geiger mode APD array
… capable of producing waveforms with OOK and PPM modulations at a variety of symbol rates and duty cycles. Using this pattern generator, I tested the receiver properties over a wide range of data rates and illumination levels, and was able to demonstrate the capability for error-free …
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Implications of Fiber Nonlinearities on Coherent Optical Fiber Communications
… this target by increasing the cardinality of modulation formats is at the expense of a reduced system tolerance to transmission impairments with the capacity ultimately limited by Kerr fiber nonlinearities. The research presented in this thesis focuses on exploring solutions to fulfill the …
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Μελέτη αλγορίθμων ψηφιακής επεξεργασίας σήματος για ομόδυνο δέκτη QPSK σε οπτικά συστήματα μεγάλων αποστάσεων υψηλής φασματικής απόδοσης
… the merits and implications of using multilevel modulation formats in optical communications systems. Following the trend in academia and industry, special focus is placed on quadrature phase-shift keying (QPSK), and specifically on polarization division multiplexed (PDM) QPSK. A special kind of …
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Defeating eavesdropping with quantum illumination
… for Alice, as well as various high-order modulation formats for the passive eavesdropping case. Finally, this thesis extends previous analysis to consider how Alice and Bob can minimize their vulnerability to Eve's doing active eavesdropping, i.e., when she injects her own light into the …
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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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Transceiver design and system optimization for ultra-wideband communications
… limited power spectral density, specific modulation formats, and a highly dispersive channel. The effect of self-interference (SI) and inter-symbol interference (ISI) on channel capacity is determined, and modulation formats that mitigate against this effect is identified. Spreading gains …
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DSP implementation of trellis coded modulation and distributed space time coding
Trellis coded modulation (TCM) combines convolutional coding with modulation, and offers approximately 2--3 dB of coding gain without requiring a corresponding bandwidth expansion. This thesis describes the process of encoding TCM, convolutional codes, decoding using the Viterbi Algorithm (VA), …
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40Gbit/s dispersion managed soliton transmission
… with varying channel separation. Three modulation formats are examined over the single mode fibre span. It is found that the dispersion managed soliton is not suitable for terrestrial style systems and that return-to-zero was the optimum format for the considered system.
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Multilevel Nyquist-WDM Ultra-Long-Haul Coherent Optical Transmission Systems
… to be coherent detection. Rather than intensity modulation direct detection systems, such solution enables to implement new multilevel transmission systems, allowing a more efficient use of the optical transmission bandwidth. These novel coherent optical communication systems have been made …
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High dimensionality carrierless amplitude phase modulation technique for radio over fiber system
Advanced modulation formats such as carrierless amplitude phase (CAP) modulation technique is one of the solutions to increase flexibility and high bit rates to support multi-level and multi-dimensional modulations with the absence of sinusoidal carrier. Recent work are focussing on the 2D CAP-64 …
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Modeling and performance evaluation of free space optical link for ground-to-train communications
… detection receiver, that utilize RZ and NRZ OOK modulation formats at 2.5 Gbps. In addition, multiple transmitters concept has been implemented to enhance the link performance, in which single, dual, triple, and quad transmitters have been developed. Furthermore, geometrical parameters have been …
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Design and Analysis of OFDM System for Powerline Based Communication
… environments. Coupled with advances in new modulation techniques, Orthogonal Frequency Division Multiplexing (OFDM) is a well-known digital multicarrier communication technique and one of the best methods of digital data transmission over a limited bandwidth. The main aim of this research is …
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Receivers for energy efficient optical interconnects
… growing bandwidth requirements. Both intensity modulation direct detection (IM-DD) optical links and coherent optical links are employed. The development of the optical interconnects is performed under tight power constraints due to inherent cooling limitations. Therefore, there has been a …
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Digital equalization techniques for the compensation of nonlinear impairments in long-haul coherent optical communication systems
… to the state-of-the-art binary intensity-modulation direct-detection receivers. A precursor to this development was the introduction in the early 2000 of differential phase shift keying in conjunction with a direct-detection using a delay interferometer. The advantages of latter modulation …
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Multi-impairment and multi-channel optical performance monitoring
… date for the bit-rate of 40Gbit/s with amplitude modulation formats.
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