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 43 for “"direct-sequence spread spectrum"”.
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An eigenstructure technique for direct sequence spread spectrum synchronization
An important aspect of all spread spectrum receivers is synchronization. The harsh radio environment has necessitated the development of fast and robust techniques. Current techniques for direct sequence spread spectrum (DSSS) synchronization, although rapid, are not robust to multiple access …
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Acquisition of pseudonoise sequences in direct-sequence spread-spectrum systems
… for the acquisition of a pseudonoise (PN) sequence in a baseband direct sequence spread-spectrum (DS/SS) system are investigated. First, we consider acquisition schemes for receivers with chip synchronization, that is, the chips of the transmitter and receiver PN sequence generator are …
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Sequence Synchronisation in Chaos-based Direct Sequence Spread Spectrum Communication Systems
… into the modelling and performance of sequence synchronisation in Chaos-based Direct Sequence Spread Spectrum (CDS-SS) communication systems with the aims of identifying the existing gaps in research and suggesting a new and accurate modelling approach. The CDS-SS systems offer physical …
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Investigation into variable shift keying using direct sequence spread spectrum techniques
… Phase Shift Keying) and the use of DSSS (Direct Sequence Spread Spectrum) techniques to achieve carrier synchronization and hence coherent demodulation in the receiver. VPSK is a new and relatively unknown modulation scheme in which data bits are encoded using patented algorithms designed …
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Interference characterization and suppression for multiuser direct-sequence spread-spectrum system
… techniques, multicode (MCD) and variable-spreading-gain (VSG), under the presence of multiple-access (user-to-user) interferences (MAI) and multipath interferences. The uniqueness of our study is that in bit-error-rate evaluation, instead of approximating the interference as Gaussian noise …
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Serial acquisition of PN sequences in direct sequence spread spectrum communication systems
… for the acquisition of a pseudo-noise (PN) sequence in a direct-sequence spread-spectrum (DS/SS) communication system. Serial search acquisition schemes are by far the most commonly used class of acquisition schemes, due to the ease with which they are implemented. The main assumptions …
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Multi-dimensional direct-sequence spread spectrum multiple-access communication with adaptive channel coding
… of a Multi-User (MU), adaptive channel coded Direct Sequence Spread Spectrum Multiple Access (DS/SSMA) communication system. This study firstly presents and utilizes a complex Base Band(BB) DS/SSMA transmitter model, aimed at user data diversity [6] in order to realize the MU input data to the …
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Performance Analysis of Direct-Sequence Spread-Spectrum Multiple-Access Communication via Fading Channels
Made available in DSpace on 2014-12-12T20:55:03Z (GMT). No. of bitstreams: 1 8008984.pdf: 6012025 bytes, checksum: c524b9916e9e8cda650c091d5d8a6516 (MD5) Previous issue date: 1979
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Optimum linear single user detection in direct-sequence spread-spectrum multiple access systems
… asynchronous operation of the users, CDMA <i>direct-sequence 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 …
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Techniques and adaptation algorithms for direct-sequence spread-spectrum CDMA single-user detection
The capacity of a direct-sequence spread-spectrum code division multiple access (DSSS-CDMA) system is limited by multiple access interference (MAJ) and the near-far problem. There are two approaches to mitigating these problems: multiuser detection and single-user detection techniques. Multiuser …
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The Performance of Direct-Sequence Spread-Spectrum Communications With Selective Fading Channels and Rake Reception
The performance of a direct-sequence spread-spectrum communication system is evaluated for selective fading channels and rake reception. Several issues are examined that influence the probability of error of the system, and closed-form expressions are obtained for the probability of error. The …
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Feasibility of Spectrum Sharing Between Airborne Weather Radar and Wireless Local Area Networks
… the last 10 years. The shortage of available spectrum exists due to increasing demand for wireless services and current spectrum allocation regulations. To alleviate this shortage, Research aims to improve spectral efficiency and to allow spectrum sharing between separately managed and …
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Physical Layer Design for a Spread Spectrum Wireless LAN
… thesis presents a physical layer design for a direct sequence spread spectrum ISM band radio LAN system. This radio system employs spread spectrum communication technology and a differential binary phase shift keying/quadrature phase shift keying (BPSK/QPSK) non-coherent receiver to overcome …
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Range Adaptive Protocols for Wireless Multi-Hop Networks
… multi-user interference cancellation and direct-sequence spread-spectrum functionality, by encouraging multiple simultaneous connections and adaptively changing communication parameters on a per-packet basis. Through its environment characterization techniques, the adaptive direct sequence …
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DSSS detection and direction finding methods for a DSP-based small aperture DF system
… an investigation into methods for detection and direction finding of direct-sequence spread-spectrum signals (DSSS), appropriate for a particular DSP-based direction finding platform. Relevant details on DSSS and radio direction finding are presented. These are used as the theorectical basis for …
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Compressive Measurement of Spread Spectrum Signals
Spread Spectrum (SS) techniques are methods used in communication systems where the spectra of the signal is spread over a much wider bandwidth. The large bandwidth of the resulting signals make SS signals difficult to intercept using conventional methods based on Nyquist sampling. Recently, a …
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On the instrumentation of the Omniscope
… ever built-including the digital correlator, the direct sequence spread spectrum channel encoding system and powerful system and data analysis software.
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Broadband Fading Channels: Signal Burstiness and Capacity
… that for wideband fading channels the nonbursty direct-sequence spread spectrum signals have small values of fourthegy per unit energy; therefore, such signals can only achieve small rates of reliable information transfer. This result holds in general for diffuse WSSUS fading channels as well as …
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Adaptive reception for underwater communications
… scattering function by processing the received Direct Sequence Spread Spectrum (DSSS) acoustic signal. This information is used by an innovative receiver introduced for usage in the underwater environment. The research also involves the development of a robust acquisition system for the acoustic …
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