{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/69256"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/69256","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"A Study of Spread-Spectrum Multiple-Access Communications Over Fading Channels","abstract":"The performance of asynchronous direct-sequence (DS) and slow-frequency-hopped (SFH) spread-spectrum multiple-access (SSMA) communications over fading channels is investigated. Nonselective, wide-sense-stationary uncorrelated-scattering time- or frequency-selective, and specular multipath fading channels are considered. Thermal noise modeled as additive white Gaussian noise (AWGN) is also assumed to be present at the receiver.","abstract_html":"The performance of asynchronous direct-sequence (DS) and slow-frequency-hopped (SFH) spread-spectrum multiple-access (SSMA) communications over fading channels is investigated. Nonselective, wide-sense-stationary uncorrelated-scattering time- or frequency-selective, and specular multipath fading channels are considered. Thermal noise modeled as additive white Gaussian noise (AWGN) is also assumed to be present at the receiver.","abstract_has_math":false,"creators":["Geraniotis, Evaggelos A."],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Electrical Engineering","degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2014,"date_issued":"2014-12-15T19:04:32Z","date_published":"2014-12-15T19:04:32Z","updated_at":"2026-07-22T22:26:00Z","subjects":["Engineering, Electronics and Electrical"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["(UMI)AAI8324556"],"render_values":[{"text":"(UMI)AAI8324556","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/69256","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Geraniotis, Evaggelos A."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2014-12-15T19:04:32Z","10000-01-01","1983"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Electrical Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Engineering, Electronics and Electrical"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/69256","(UMI)AAI8324556"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["The performance of asynchronous direct-sequence (DS) and slow-frequency-hopped (SFH) spread-spectrum multiple-access (SSMA) communications over fading channels is investigated. Nonselective, wide-sense-stationary uncorrelated-scattering time- or frequency-selective, and specular multipath fading channels are considered. Thermal noise modeled as additive white Gaussian noise (AWGN) is also assumed to be present at the receiver.","For DS/SSMA systems with coherent demodulation, we develop a method for approximating the average probability of error, which has very satisfactory accuracy and required computational effort, growing linearly with the number of simultaneous transmitters and the length of the signature sequences. For the performance of DS/SSMA systems over AWGN and fading channels, we establish for all cases in which a strong stable path for the desired signal exists, that DS modulation discriminates against other signals or other paths and achieves a satisfactory performance at the expense of possibly increasing the length of the signature sequences. If there is no strong stable path then we find that the performance of DS/SSMA systems with conventional matched filter receivers is not satisfactory. Post-detection processing at the receiver or adaptive equalization look more promising but they lie beyond the scope of this thesis.","We first introduce a suitable model for SFH/SSMA systems. Then we develop several bounds and approximations on the average probability of error. These are easy to evaluate, and they apply to a variety of cases. Our study of the performance of SFH/SSMA communications via fading channels reveals that slow-frequency-hopping alone (with hopping rates no larger than the data rate) is not sufficient to provide multiple-access capability and combat nonselective or selective fading. Fortunately, the natural mechanism that frequency-hopping provides facilitates the use of error-control coding. Although coding is not treated in this thesis, the results can be utilized to determine the performance of error-control coding in SFH/SSMA systems. This is partly due to the fact that one of the techniques that we developed for the performance evaluation of uncoded SFH/SSMA systems is applicable to coded systems as well.","Made available in DSpace on 2014-12-15T19:04:32Z (GMT). No. of bitstreams: 1 8324556.pdf: 5378825 bytes, checksum: e2ebf60ca1ee72b74c47483392069e86 (MD5) Previous issue date: 1983","Embargo set by: Seth Robbins for item 69422 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","U of I Only","168 p.","Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1983."]},{"key":"dc:title","label":"Title","values":["A Study of Spread-Spectrum Multiple-Access Communications Over Fading Channels"]}]}],"canonical_facts":{"dc:creator":["Geraniotis, Evaggelos A."],"dc:date":["2014-12-15T19:04:32Z","10000-01-01","1983"],"dc:description":["The performance of asynchronous direct-sequence (DS) and slow-frequency-hopped (SFH) spread-spectrum multiple-access (SSMA) communications over fading channels is investigated. Nonselective, wide-sense-stationary uncorrelated-scattering time- or frequency-selective, and specular multipath fading channels are considered. Thermal noise modeled as additive white Gaussian noise (AWGN) is also assumed to be present at the receiver.","For DS/SSMA systems with coherent demodulation, we develop a method for approximating the average probability of error, which has very satisfactory accuracy and required computational effort, growing linearly with the number of simultaneous transmitters and the length of the signature sequences. For the performance of DS/SSMA systems over AWGN and fading channels, we establish for all cases in which a strong stable path for the desired signal exists, that DS modulation discriminates against other signals or other paths and achieves a satisfactory performance at the expense of possibly increasing the length of the signature sequences. If there is no strong stable path then we find that the performance of DS/SSMA systems with conventional matched filter receivers is not satisfactory. Post-detection processing at the receiver or adaptive equalization look more promising but they lie beyond the scope of this thesis.","We first introduce a suitable model for SFH/SSMA systems. Then we develop several bounds and approximations on the average probability of error. These are easy to evaluate, and they apply to a variety of cases. Our study of the performance of SFH/SSMA communications via fading channels reveals that slow-frequency-hopping alone (with hopping rates no larger than the data rate) is not sufficient to provide multiple-access capability and combat nonselective or selective fading. Fortunately, the natural mechanism that frequency-hopping provides facilitates the use of error-control coding. Although coding is not treated in this thesis, the results can be utilized to determine the performance of error-control coding in SFH/SSMA systems. This is partly due to the fact that one of the techniques that we developed for the performance evaluation of uncoded SFH/SSMA systems is applicable to coded systems as well.","Made available in DSpace on 2014-12-15T19:04:32Z (GMT). No. of bitstreams: 1 8324556.pdf: 5378825 bytes, checksum: e2ebf60ca1ee72b74c47483392069e86 (MD5) Previous issue date: 1983","Embargo set by: Seth Robbins for item 69422 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","U of I Only","168 p.","Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1983."],"dc:identifier":["http://hdl.handle.net/2142/69256","(UMI)AAI8324556"],"dc:subject":["Engineering, Electronics and Electrical"],"dc:title":["A Study of Spread-Spectrum Multiple-Access Communications Over Fading Channels"],"dc:type":["text"],"thesis:degree_discipline":["Electrical Engineering"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:26:00Z"}