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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Bandwidth efficient reduced-complexity MT-DS-SS via reduced subcarrier frequency spacing /

Sen, Indranil. January 2004 (has links)
Thesis (M.S.)--Ohio University, June, 2004. / Includes bibliographical references (p. 94-95).
52

Analysis of the probability of error in frequency hopping multiple access system /

Shin, Hong-Sup. January 1997 (has links)
Thesis (Ph. D.)--University of Washington, 1997. / Vita. Includes bibliographical references (leaves [116]-119).
53

Determination of maximal-length sequences by weight distribution analysis.

Faulkner, Sean (Sean Anthony), Carleton University. Dissertation. Engineering, Electrical. January 1989 (has links)
Thesis (M. Eng.)--Carleton University, 1989. / Also available in electronic format on the Internet.
54

Composite sequences for rapid acquisition of direct-sequence spread spectrum signals.

Faulkner, Sean (Sean Anthony), Carleton University. Dissertation. Engineering, Electrical. January 1992 (has links)
Thesis (Ph. D.)--Carleton University, 1992. / Also available in electronic format on the Internet.
55

Kalman filtering of narrowband interference from direct sequence spread spectrum communications systems.

Kozminchuk, Brian William, Carleton University. Dissertation. Engineering, Electrical. January 1992 (has links)
Thesis (Ph. D.)--Carleton University, 1993. / Also available in electronic format on the Internet.
56

Ultra wide bandwidth spread spectrum impulse radio for wireless multi-access communications /

Boubaker, Nejib. January 2005 (has links)
Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2005. / Includes bibliographical references (leaves 103-109). Also available in electronic version.
57

Bandwidth efficient reduced-complexity MT-DS-SS via reduced subcarrier frequency spacing

Sen, Indranil. January 2004 (has links)
Thesis (M.S.)--Ohio University, June, 2004. / Title from PDF t.p. Includes bibliographical references (p. 94-95)
58

Performance of multitone direct sequence speread [sic] spectrum in the presence of imperfect carrier synchronization

Li, Hongxiang. January 2004 (has links)
Thesis (M.S.)--Ohio University, August, 2004. / Title from PDF t.p. Includes bibliographical references (p. 81-83)
59

Enhanced Implementations for Arbitrary-Phase Spread Spectrum Waveforms

Fletcher, Michael John 18 June 2019 (has links)
The use of practically non-repeating spreading codes to generate sequence-based spread spectrum waveforms is a strong method to improve transmission security, by limiting an observers opportunity to cross-correlate snapshots of the signal into a coherent gain. Such time-varying codes, particularly when used to define multi-bit resolution arbitrary-phase waveforms, also present significant challenges to the intended receiver, which must synchronize correlator processing to match the code every time it changes. High-order phase shift keying (PSK) spread modulations do, however, provide an overall whiter spectral response than legacy direct sequence spread spectrum (DSSS) signals. Further, the unique ability to color the output signal spectrum offers new advantages to optimize transmission in a non-white frequency channel and to mitigate observed interference. In high data rate applications, the opportunity to inject a time-aligned co-channel underlay-based watermark for authentication at the receiver is an effective method to enhance physical layer (PHY) security for virtually any primary network waveform. This thesis presents a series of options to enhance the implementation of arbitrary-phase chaotic sequence-based spread spectrum waveforms, including techniques to significantly reduce fallthrough correlator hardware resources in low-power sensing devices for only minor performance loss, capabilities for programming chosen frequency domain spectra into the resulting spread spectrum signal, and design considerations for underlay watermark-based PHY-layer firewalls. A number of hardware validated prototypes were built on an Intel Arria 10 SoC FPGA to provide measurable results, achieving substantial computational resource gains and implementation flexibility. / Master of Science / This thesis presents a series of options for enhancing the implementation of arbitrary-phase spread spectrum waveforms, a highly-secure class of wireless technologies, in order to reduce design complexity with minimal loss, provide methods for real-time performance adaptations, and extend the traditional application space for increased security of communications in other networks. A number of enhanced hardware prototypes were implemented to provide measurable results, achieving substantial computational resource gains and design flexibility. Given the computational resources and power constraints of devices in the Internet of Things (IoT), the signal detection loss of 2.10 dB for reducing the hardware logic utilization of the brute force fallthrough correlator by more than 76% (and eliminating the need to dedicate computationally-expensive embedded multipliers) is a very reasonable trade. While the waveform is fundamentally designed for increased security, adapting to widespread and/or commercial use may allow some sacrifice of the signal’s ability to avoid interception/detection to improve performance in undesirable operating conditions. In a similar, yet reversed, case, injecting a watermarking signature at the physical layer (PHY) of less-secure wireless technologies for receiver-side authentication also proves to be beneficial.
60

Performance of a wideband CDMA system under multipath fading

Noon, David P., Jr. 17 November 2012 (has links)
The objective of this thesis is to determine the average probability of bit error of an asynchronous, noncoherent, direct-sequence, code-division multiple-access (CDMA) system using wideband M-ary FSK as bandpass modulation. The immediate analysis and determination of the average probability of bit error is made inherently more difficult because of two random effects. The first disturbance encountered in the analysis is the existence of additive, white, Gaussian noise and multi-user noise. The second disturbance, which is more difficult to analyze, is the effect of multipath fading, which is caused by reflections of the transmitted signal through the propagating medium to the receiver. / Master of Science

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