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 83 for “"direct sequence"”.
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Channel-coded time-hopping and direct-sequence ultrawideband systems
… propose an EXIT chart aided iteratively detected Direct-Sequence (DS) Code Division Multiple Access (CDMA) system, which uses 2-stage concatenation of an inner and outer encoders, with their corresponding decoders exchanging extrinsic information for the sake of enhancing the attainable system …
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An eigenstructure technique for direct sequence spread spectrum synchronization
… and robust techniques. Current techniques for direct sequence spread spectrum (DSSS) synchronization, although rapid, are not robust to multiple access interference. This is because they require the spreading codes of the multiple access network to have very good cross correlation properties. …
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Cooperative diversity aided direct-sequence code-division multiple-access systems
In relay-assisted direct-sequence code-division multiple-access (DS-CDMA) systems, the distance between the relay and the destination receiver may be significantly shorter than that between the source transmitter and the destination receiver. Therefore, the transmission power of the relay may be …
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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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Capacity improvements for a direct-sequence code division multiple access network
… with techniques which enhance the capacity of a Direct-Sequence Code-Division-Multiple-Access (DS-CDMA) mobile telephone network. The capacity of both Private Mobile Radio (PMR) and cellular networks are derived and the many techniques which are currently available are reviewed. Areas which may …
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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
In this thesis we investigate efficient modulation and detection techniques for the uplink (i.e. transmission from mobile to base station) of a DS-CDMA network. Specifically, the thesis contains three parts. In the first part, we focus on the mobile transmitter. In particular, we evaluate and …
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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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Effects of Fading on a Multi-User Spread Spectrum System Using Direct Sequence Modulation
Made available in DSpace on 2014-12-12T20:54:39Z (GMT). No. of bitstreams: 1 7726725.pdf: 4315633 bytes, checksum: c601d8b58db1352991c5ac05952dddf9 (MD5) Previous issue date: 1977
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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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Development and Analysis of Adaptive Interference Rejection Techniques for Direct Sequence Code Division Multiple Access Systems
The inadequacy of conventional CDMA receivers in a multiple access interference-limited mobile radio environment has spurred research on advanced receiver technologies. This research investigates the use of adaptive receivers for single user demodulation to overcome some of the deficiencies of a …
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Study of Ds/ssma Receivers in the Low Frequency Band (Communications, Detection, Direct-Sequence, Multiple-Access, Spread-Spectrum)
Embargo set by: Seth Robbins for item 69513 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs
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Feasibility of Spectrum Sharing Between Airborne Weather Radar and Wireless Local Area Networks
… types of wireless local area networks, but a direct sequence spread spectrum scheme could share spectrum with airborne weather radar. Bit errors in wireless local area network links caused by airborne weather radar interference do not significantly decrease the performance of the wireless …
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