Dissertations / Theses on the topic 'Codes orthogonaux'
To see the other types of publications on this topic, follow the link: Codes orthogonaux.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Codes orthogonaux.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Baechler, Brice. "Analyse et détermination de codes doublement orthogonaux pour décodage itératif." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0019/MQ57390.pdf.
Full text
2
Cardinal, Christian. "Décodage à seuil itératif sans entrelacement des codes convolutionnels doublement orthogonaux." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/NQ65537.pdf.
Full text
3
Ouadid, Abdelkarim. "Prototype micro-électronique d'un décodeur itératif pour des codes doublement orthogonaux." Mémoire, École de technologie supérieure, 2004. http://espace.etsmtl.ca/715/1/OUADID_Abdelkarim.pdf.
Full textAbstract:
Ce mémoire porte sur le prototypage microélectronique FPGA d'un décodeur itératif doublement orthogonal issu de récents travaux de recherche. Le nouvel algorithme est simple et présente un certain nombre d'avantages par rapport aux codes turbo très prisés actuellement dans le codage de canal. En effet, ces derniers outre la complexité de leur algorithme de décodage, souffrent d'un problème de latence qui les rend inadaptés pour certaines applications, comme la téléphonie par exemple. Le décodeur utilisé, est un décodeur itératif à quantification souple, basé sur le décodage seuil tel que présenté par Massey et amélioré par l'approximation de la probabilité a posteriori (AAPP). Grâce à cette approche, on arrive à concilier complexité, latence, performance en correction d'erreurs, et haut débit de fonctionnement. Le prototype vise à valider les résultats de simulation, ainsi que l'estimation de la complexité et de la fréquence maximale que l'on peut atteindre sur des FPGA Virtex-II XC2V6000 et ceci pour différentes structures du décodeur.
4
Dru, Frédéric. "Décodage à seuil itératif des codes convolutionnels doublement orthogonaux perforés et application aux modulations multiniveaux." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ65572.pdf.
Full text
5
Grandpierre, Benoît. "Produits automorphes, classification des réseaux et théorie du codage." Electronic Thesis or Diss., Lille 1, 2009. http://www.theses.fr/2009LIL10019.
Full textAbstract:
La fonction [Phi]12 de Borcherds, forme modulaire en 26 variables pour le groupe orthogonal O+(II2,26) et le caractère déterminant, de poids singulier 12, a été construite par R.E.Borcherds en 1994 avec la théorie des produits automorphes. Elle détermine la “Fake Monster Lie Algebra”, qui joue le rôle fondamental dans la preuve de la “Moonshine Conjecture”. [Phi]12 est aussi une forme modulaire réflexive (ses zéros sont des hyperplans définissant une réflexion orthogonale de O+(II2,26)). Beaucoup d’exemples ont été construits par Borcherds, et Nikulin a montré qu’il n’y a, en principe, qu’un nombre fini de formes modulaires réflexives. Gritsenko et Nikulin ont classifié les formes modulaires réflexives dans le cas des réseaux maximaux de signature (1,2) (1998 - 2002). Enfin, d’autres exemples importants de formes réflexives de poids singuliers ont été construits par N. Scheithauer (2000 - 2005). La classification des formes modulaires réflexives est un problème très important, de telles formes ont beaucoup d’applications dans différents domaines mathématiques et physiques : en théorie des algèbres de Kac-Moody, en géométrie algébrique, en théorie des cordes... Dans cette thèse, nous décrivons une nouvelle classe de formes modulaires réflexives associée à la fonction [Phi]12 de Borcherds. La signature des groupes orthogonaux considérés varie entre (2,3) et (2,25). Toutes les formes obtenues sont des quasi-restrictions de [Phi]12. Cette méthode, très arithmétique, nous donne plus de 60 formes modulaires réflexives, dont la première est la forme modulaire de Siegel de poids 35 construite par Igusa en 1964Borcherds’ [Phi]12 function is a modular form in 26 variables for the orthogonal group O+(II2,26) and the character determinant, of singular weight 12, it was constructed by Borcherds in 1994 together with the automorphic products theory. It determines the Fake Monster Lie Algebra, which plays the fundamental role in the proof of the Moonshine Conjecture. [Phi]12 is also a reflective form (its zeros are hyperplans of orthogonal reflections in O+(II2,26)). Many examples were constructed by Borcherds, and Nikulin has proved there is, in principle, only a finite number of reflective modular forms. Gritsenko and Nikulin classified reflective modular forms in the case of maximal lattices of signature (1,2) (1998-2002). Other important examples of reflective forms of singular weight were constructed by N. Scheithauer (2000 - 2005). The classification of reflective modular forms is a very important question, such forms have many applications in different fields of mathematics and physics : in the theory of Kac-Moody algebras, in algebraic geometry, in string theory... In this thesis, we describe a new class of reflective forms related to the Borcherds’function [Phi]12. The signature of the orthogonal groups we consider goes between (2,3) and (2,25). All the forms we obtain are quasi pull-back of [Phi]12. This arithmetic method gives more than 60 reflective modular forms, the first of them being the Siegel modular form of weight 35 constructed by Igusa in 1964
6
Grandpierre, Benoît. "Produits automorphes, classification des réseaux et théorie du codage." Thesis, Lille 1, 2009. http://www.theses.fr/2009LIL10019/document.
Full textAbstract:
La fonction [Phi]12 de Borcherds, forme modulaire en 26 variables pour le groupe orthogonal O+(II2,26) et le caractère déterminant, de poids singulier 12, a été construite par R.E.Borcherds en 1994 avec la théorie des produits automorphes. Elle détermine la “Fake Monster Lie Algebra”, qui joue le rôle fondamental dans la preuve de la “Moonshine Conjecture”. [Phi]12 est aussi une forme modulaire réflexive (ses zéros sont des hyperplans définissant une réflexion orthogonale de O+(II2,26)). Beaucoup d’exemples ont été construits par Borcherds, et Nikulin a montré qu’il n’y a, en principe, qu’un nombre fini de formes modulaires réflexives. Gritsenko et Nikulin ont classifié les formes modulaires réflexives dans le cas des réseaux maximaux de signature (1,2) (1998 - 2002). Enfin, d’autres exemples importants de formes réflexives de poids singuliers ont été construits par N. Scheithauer (2000 - 2005). La classification des formes modulaires réflexives est un problème très important, de telles formes ont beaucoup d’applications dans différents domaines mathématiques et physiques : en théorie des algèbres de Kac-Moody, en géométrie algébrique, en théorie des cordes... Dans cette thèse, nous décrivons une nouvelle classe de formes modulaires réflexives associée à la fonction [Phi]12 de Borcherds. La signature des groupes orthogonaux considérés varie entre (2,3) et (2,25). Toutes les formes obtenues sont des quasi-restrictions de [Phi]12. Cette méthode, très arithmétique, nous donne plus de 60 formes modulaires réflexives, dont la première est la forme modulaire de Siegel de poids 35 construite par Igusa en 1964Borcherds’ [Phi]12 function is a modular form in 26 variables for the orthogonal group O+(II2,26) and the character determinant, of singular weight 12, it was constructed by Borcherds in 1994 together with the automorphic products theory. It determines the Fake Monster Lie Algebra, which plays the fundamental role in the proof of the Moonshine Conjecture. [Phi]12 is also a reflective form (its zeros are hyperplans of orthogonal reflections in O+(II2,26)). Many examples were constructed by Borcherds, and Nikulin has proved there is, in principle, only a finite number of reflective modular forms. Gritsenko and Nikulin classified reflective modular forms in the case of maximal lattices of signature (1,2) (1998-2002). Other important examples of reflective forms of singular weight were constructed by N. Scheithauer (2000 - 2005). The classification of reflective modular forms is a very important question, such forms have many applications in different fields of mathematics and physics : in the theory of Kac-Moody algebras, in algebraic geometry, in string theory... In this thesis, we describe a new class of reflective forms related to the Borcherds’function [Phi]12. The signature of the orthogonal groups we consider goes between (2,3) and (2,25). All the forms we obtain are quasi pull-back of [Phi]12. This arithmetic method gives more than 60 reflective modular forms, the first of them being the Siegel modular form of weight 35 constructed by Igusa in 1964
7
Odhiambo, Michael Derrick. "Spatial data focusing using direct sequence spread spectrum modulation." Electronic Thesis or Diss., Sorbonne université, 2021. http://www.theses.fr/2021SORUS060.
Full textAbstract:
Ce travail propose la mise en œuvre de la focalisation spatiale de données (FSD) en utilisant des techniques de spectre étalé. La FSD a récemment été proposée comme alternative aux schémas classiques de focalisation de puissance dans des scenarios de geocasting (diffusion géolocalisée des données). Dans la FSD, ce sont de données à transmettre qui sont traitées de telle qu'elles ne peuvent être décodées qu'à un endroit prédéfini. Ce travail exploite la double orthogonalité due aux IQ et aux séquences orthogonales d'étalement Gold pour concevoir le schéma de focalisation spatiale de données basé sur le IQ et le spectre étalé (DSSS-SDF-IQ). Il est démontré que la FSD permet d’obtenir des faisceaux plus étroits par rapport aux scénarios de focalisation de puissance. La robustesse du schéma proposé est ensuite démontrée par sa mise en œuvre sur un modèle de canal à trajets multiples. Il est démontré que la FSD atteint une largeur de faisceau allant jusqu'à 1 degré avec un réseau de 4 antennes seulement. Le chapitre 1 introduit le concept de géocasting. Le chapitre 2 passe en revue les différentes techniques qui permettent d'obtenir des capacités directionnelles sur les stations de base. Le chapitre 3 présente les principes de l'étalement du spectre par séquence directe basé sur la FSD. Le chapitre 4 étudie l'influence du canal à trajets multiples sur le schéma proposé. Pour tous les cas étudiés ci-dessus, des simulations pertinentes sont mises en œuvre pour valider les discussions. Le chapitre 5 résume le travail avec une conclusion et une perspective sur les orientations possibles de la recherche futureThis work proposes the implementation of Spatial Data Focusing (SDF) using spread spectrum techniques. SDF was recently proposed as a candidate alternative to classical power focusing schemes in wireless geocasting applications. Unlike power focusing approaches where radiated power is directed to a defined direction, in SDF, it is the data to be transmitted that is processed in such a manner that it can only be decoded at a predefined location. This work exploits the dual orthogonality due to classical quadrature components and orthogonal Gold spreading sequences to design the IQ and spread spectrum based spatial data focusing (DSSS-SDF-IQ) scheme. It is demonstrated that SDF attains better spatial selectivity than classical power focusing for a given antenna array size. The robustness of the proposed scheme is subsequently demonstrated by implementing it over a classical Urban Canyon 6-ray multipath channel model, where it is shown that the scheme can exhibit beamwidth as narrow as 1 degree with only a 4-antenna array. In SDF, the beamwidth is defined as the area within which data can be decoded as opposed to classical half power beamwidth. Chapter 1 introduces the concept of geocasting. Chapter 2 reviews the different techniques that enable directional capabilities on base stations. Chapter 3 introduces the principles of direct sequence spread spectrum based SDF. Chapter 4 investigates the influence of multipath channel on DSSS-SDF scheme. For all the cases studied above, relevant simulations are implemeneted to validate the discussions. Chapter 5 summarizes the work with a conclusion and perspective on possible future research directions
8
Semerciler, Salih. "Coded orthogonal signaling." Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/23567.
Full text
9
Merensky, Alexander Mark. "A multi-dimensional code-division-multiplexed OFDMA modem using cyclic rotated orthogonal complete complementary codes." Diss., University of Pretoria, 2012. http://hdl.handle.net/2263/31146.
Full text
10
Boussebt, Amina. "Etude et mise en oeuvre de la technologie Li-Fi pour un lit de bébé connecté sans fil et sans radio." Electronic Thesis or Diss., Limoges, 2023. http://www.theses.fr/2023LIMO0091.
Full textAbstract:
Le domaine de la télésurveillance a connu un grand essor ces dernières décennies et concerne divers contextes par exemple en milieu hospitalier, en maison de retraite, chez les particuliers. La majorité des systèmes de télésurveillance existants aujourd’hui reposent sur la technologie des radiofréquences (RF). Nous proposons dans cette thèse, des travaux portant sur la télésurveillance dans un contexte nouveau qui concerne une crèche. Les RF présentant certains inconvénients, comme l’impact des interférences électromagnétiques, mais aussi des failles de sécurité, une solution alternative est la technologie de communication par optique sans fil. Ainsi, nous avons étudié l'utilisation de la technologie infrarouge pour la transmission simultanée de données issues de capteurs placés sur les pieds des lits de bébé mais aussi sur les bébés couchés dans leur lit au sein de la crèche. Le système de réception est constitué de photodiodes situées aux coins d'un panneau d'éclairage central au plafond de l'environnement. La simulation du canal réalisée grâce à la technique de lancer de rayons associés à la méthode de Monte-Carlo a permis de déterminer le gain du canal pour chaque dispositif. Plusieurs scénarios de déploiement ont été définis en considérant le caractère amovible ou fixe des dispositifs et l’interchangeabilité des lits dans la pièce. Le partage du canal utilise la technique d’accès multiple par répartition de codes (OCDMA) associée aux codes optiques orthogonaux (OOC) dont la principale limitation est l’interférence d’accès multiple (IAM). Les performances de la modulation binaire par position d’impulsion (2-PPM) avec OCDMA et un décodage souple en réception ont été établies théoriquement et par simulation pour les différents scénarios définis considérant un réseau de 11 utilisateurs constitué de 8 lits et 3 dispositifs portés par des bébés. Les résultats ont été obtenus avec des récepteurs conventionnels par corrélation sans et avec limiteur puis un récepteur à annulation parallèle d’interférence plus efficace pour réduire l’impact de l’IAM. De plus, la faisabilité de l’utilisation de la technique OCDMA pour la transmission simultanée en optique sans fil a été mise en évidence par des expérimentations menées grâce à un banc de test développé en radio logicielle. Le banc a été mis en place, en utilisant des USRP (Universal Software Radio Peripheral) et des front-ends optique sans fil développés spécifiquementThe field of the remote monitoring has experienced significant advancements in recent decades, and now covers different contexts, such as hospitals, retirement homes, and private homes also. The majority of existing systems are based on radio frequency technology (RF).We propose in this thesis, research focused on remote monitoring in a new context involving a nursery. Given the limitations of RF technology, including the impact of electromagnetic interference, and security vulnerabilities, an alternative solution is optical wireless communication technology. Therefore, we investigated the use of infrared technology for simultaneous transmission of data collected from sensors placed on the foot of baby beds, and also on the babies themselves lying in their beds within the nursery. The reception system consists of photodiodes positioned at the corners of a central lighting panel on the celling. The channel simulation carried out using ray-tracing and Monte-Carlo methods was used to determine the channel gain for each device. Several deployment scenarios were defined, considering the nature of the devices (removable or fixed) and the interchangeability of beds in the room. The channel sharing employs the code division multiple access (OCDMA) associated with the optical orthogonal codes (OOC) with the primary constraint being the137 multiple access interference (MAI). The performance of binary pulse position modulation (2- PPM) with OCDMA and soft decoding in reception was studied theoretically and by simulation involving the different scenarios. These scenarios consider a network of 11 users, consisting of 8 beds and 3 devices carried by babies. Results were obtained using the conventional correlation receiver without and with hard limiters, as well as a parallel interference cancellation receiver to reduce the impact of MAI. Additionally, the feasibility of implementing OCDMA technology for simultaneous optical wireless communication transmission was demonstrated through experimental work using a test bench developed in software-defined radio. The test bench was established using universal software radio peripheral (USRP), and specially designed wireless optical front-ends
11
Arlery, Fabien. "Formes d’ondes MSPSR, traitements et performances associés." Thesis, Evry, Institut national des télécommunications, 2017. http://www.theses.fr/2017TELE0005/document.
Full textAbstract:
Aujourd’hui, les systèmes MSPSR (Multi-Static Primary Surveillance Radar) passifs se sont installés de manière durable dans le paysage de la surveillance aérienne [1]. L’intérêt que suscitent ces nouveaux systèmes provient du fait qu’en comparaison aux radars mono-statiques utilisés actuellement, les systèmes MSPSR reposent sur une distribution spatiale d’émetteurs et de récepteurs offrant des avantages en termes de fiabilité (redondance), de coûts (absence de joints tournants et émetteurs moins puissants) et de performances (diversité spatiale). Toutefois, le défaut majeur du MSPSR passif réside en l’absence de formes d’ondes dédiées due à l’exploitation d’émetteurs d’opportunités tels que les émetteurs de radio FM (Frequency Modulation) et/ou de DVB-T (Digital Video Broadcasting-Terrestrial) [2]. Afin de pallier à ce défaut, il est envisagé d’utiliser des émetteurs dédiés permettant l’emploi de formes d’ondes optimisées pour une application radar, on parle alors de MSPSR actif. Cette thèse se place dans ce cadre et a pour objectif d’étudier et de définir la ou les formes d’ondes ainsi que les traitements associés permettant d’atteindre de meilleurs performances : une meilleure flexibilité sur la disposition du système (positionnement des émetteurs libres), une continuité de service (non dépendance d’un système tiers) et de meilleurs performances radars (e.g. en terme de précision des mesures, détections, …). Dans ce but, cette thèse étudie : - Les critères de sélection des codes : comportement des fonctions d’ambiguïtés, PAPR (Peak to Average Power Ratio), efficacité spectrale, etc... ; - Les formes d’ondes utilisées en télécommunication (scrambling code, OFDM) afin d’identifier leur possible réemploi pour une application radar ; - L’utilisation d’algorithmes cycliques pour générer des familles de séquences adaptées à notre problème ; - Une approche basée sur une descente de gradient afin de générer des familles de codes de manière plus efficiente ; - Et l’évaluation des performances de ces différents algorithmes à travers l’établissement d’une borne supérieure sur le niveau maximum des lobes secondaires et à travers le dépouillement des données enregistrées suite à des campagnes d’essaisNowadays, MSPSR (Multi-Static Primary Surveillance Radar) systems are sustainably settled in air surveillance program [1]. Compared to mono-static radar currently in use, an MSPSR system is based on a sparse network of transmitters (Tx) and receivers (Rx) interconnected to a Central Unit and offers advantages in terms of reliability, cost and performance.Two kinds of MSPSR systems exist: the Passive form and the Active one. While the Passive MSPSR uses transmitters of opportunity such as radio Frequency Modulation (FM) transmitters and/or Digital Video Broadcasting-Terrestrial (DVB-T) transmitters [2], the Active MSPSR uses dedicated transmitters, which emit a waveform that is controlled and designed for a radar application. Each receiver processes the signal coming from all transmitters and reflected on the targets; and the Central Unit restores the target location by intersecting “ellipsoids” from all (transmitter, receiver) pairs. Compared to passive MSPSR, the main advantages of the active MSPSR are the use of dedicated waveforms that allow reaching better performances (like a better association of the transmitters’ contributions at the receiver level); more flexibility in the deployment of transmitters and receivers station (in order to meet the requirements in localisation accuracy and in horizontal and altitude coverages); and the guarantee of having a service continuity. On this purpose, this thesis analyses the differents codes criteria such as the ambiguity function behaviour, the PAPR (Peak to Average Power Ratio), the spectrum efficiency, etc... . Then, in order to find dedicated waveforms for MSPSR systems, one solution is to find easily-constructed families of sequences. Thus building on the works carried out by the Telecommunication field for solving multi-user issues, this document investigates the application of spreading codes and OFDM signals in MSPSR concept. Besides, another solution is to directly generate a set of sequences. Based on cyclic algorithms in [3] we derive a new algorithm that allows to optimize sets of sequences. Similarly, using a gradient descent approach, we develop a more efficient algorithm than the cyclic one. Finally, in order to evaluate the performances of the different algorithms, this thesis generalizes the Levenshtein Bound, establishes new lower bounds on the PSLR (Peak Sidelobe Level Ratio) in mismatched filter case, and studies real data recorded during some trials
12
Arlery, Fabien. "Formes d’ondes MSPSR, traitements et performances associés." Electronic Thesis or Diss., Evry, Institut national des télécommunications, 2017. http://www.theses.fr/2017TELE0005.
Full textAbstract:
Aujourd’hui, les systèmes MSPSR (Multi-Static Primary Surveillance Radar) passifs se sont installés de manière durable dans le paysage de la surveillance aérienne [1]. L’intérêt que suscitent ces nouveaux systèmes provient du fait qu’en comparaison aux radars mono-statiques utilisés actuellement, les systèmes MSPSR reposent sur une distribution spatiale d’émetteurs et de récepteurs offrant des avantages en termes de fiabilité (redondance), de coûts (absence de joints tournants et émetteurs moins puissants) et de performances (diversité spatiale). Toutefois, le défaut majeur du MSPSR passif réside en l’absence de formes d’ondes dédiées due à l’exploitation d’émetteurs d’opportunités tels que les émetteurs de radio FM (Frequency Modulation) et/ou de DVB-T (Digital Video Broadcasting-Terrestrial) [2]. Afin de pallier à ce défaut, il est envisagé d’utiliser des émetteurs dédiés permettant l’emploi de formes d’ondes optimisées pour une application radar, on parle alors de MSPSR actif. Cette thèse se place dans ce cadre et a pour objectif d’étudier et de définir la ou les formes d’ondes ainsi que les traitements associés permettant d’atteindre de meilleurs performances : une meilleure flexibilité sur la disposition du système (positionnement des émetteurs libres), une continuité de service (non dépendance d’un système tiers) et de meilleurs performances radars (e.g. en terme de précision des mesures, détections, …). Dans ce but, cette thèse étudie : - Les critères de sélection des codes : comportement des fonctions d’ambiguïtés, PAPR (Peak to Average Power Ratio), efficacité spectrale, etc... ; - Les formes d’ondes utilisées en télécommunication (scrambling code, OFDM) afin d’identifier leur possible réemploi pour une application radar ; - L’utilisation d’algorithmes cycliques pour générer des familles de séquences adaptées à notre problème ; - Une approche basée sur une descente de gradient afin de générer des familles de codes de manière plus efficiente ; - Et l’évaluation des performances de ces différents algorithmes à travers l’établissement d’une borne supérieure sur le niveau maximum des lobes secondaires et à travers le dépouillement des données enregistrées suite à des campagnes d’essaisNowadays, MSPSR (Multi-Static Primary Surveillance Radar) systems are sustainably settled in air surveillance program [1]. Compared to mono-static radar currently in use, an MSPSR system is based on a sparse network of transmitters (Tx) and receivers (Rx) interconnected to a Central Unit and offers advantages in terms of reliability, cost and performance.Two kinds of MSPSR systems exist: the Passive form and the Active one. While the Passive MSPSR uses transmitters of opportunity such as radio Frequency Modulation (FM) transmitters and/or Digital Video Broadcasting-Terrestrial (DVB-T) transmitters [2], the Active MSPSR uses dedicated transmitters, which emit a waveform that is controlled and designed for a radar application. Each receiver processes the signal coming from all transmitters and reflected on the targets; and the Central Unit restores the target location by intersecting “ellipsoids” from all (transmitter, receiver) pairs. Compared to passive MSPSR, the main advantages of the active MSPSR are the use of dedicated waveforms that allow reaching better performances (like a better association of the transmitters’ contributions at the receiver level); more flexibility in the deployment of transmitters and receivers station (in order to meet the requirements in localisation accuracy and in horizontal and altitude coverages); and the guarantee of having a service continuity. On this purpose, this thesis analyses the differents codes criteria such as the ambiguity function behaviour, the PAPR (Peak to Average Power Ratio), the spectrum efficiency, etc... . Then, in order to find dedicated waveforms for MSPSR systems, one solution is to find easily-constructed families of sequences. Thus building on the works carried out by the Telecommunication field for solving multi-user issues, this document investigates the application of spreading codes and OFDM signals in MSPSR concept. Besides, another solution is to directly generate a set of sequences. Based on cyclic algorithms in [3] we derive a new algorithm that allows to optimize sets of sequences. Similarly, using a gradient descent approach, we develop a more efficient algorithm than the cyclic one. Finally, in order to evaluate the performances of the different algorithms, this thesis generalizes the Levenshtein Bound, establishes new lower bounds on the PSLR (Peak Sidelobe Level Ratio) in mismatched filter case, and studies real data recorded during some trials
13
Gallagher, Daniel. "ULTRA-WIDEBAND ORTHOGONAL FREQUENCY CODED SAW CORRELATORS." Master's thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3950.
Full textAbstract:
Ultra–wideband (UWB) communication new technology with ability to share the FCC allocated frequency spectrum, large channel capacity and data rate, simple transceiver architecture and high performance in noisy environments. Such communication advantages have paved the way for emerging wireless technologies such as wireless high definition video streaming, wireless sensor networks and more. This thesis examines orthogonal frequency coded surface acoustic wave (SAW) correlators for use in advanced UWB communication systems. Orthogonal frequency coding (OFC) and pseudo-noise (PN) coding provides a means for UWB spreading of data. The use of OFC spectrally spreads a PN sequence beyond that of CDMA because of the increased bandwidth; allowing for improved correlation gain. The transceiver approach is still very similar to that of the CDMA approach but provides greater code diversity. Use of SAW correlators eliminates many of the costly components that are needed in the IF block in the transmitter and receiver, and reduces much of the signal processing requirements. The OFC SAW correlator device consists of a dispersive OFC transducer and a wideband output transducer. The dispersive filter was designed using seven contiguous chip frequencies within the transducer. Each chip is weighted in the transducer to account for the varying conductance of the chips and to compensate for the output transducer apodization. Experimental correlator results of an OFC SAW correlation filter are presented. The dispersive filter is designed using seven contiguous chip frequencies within the transducer. SAW correlators with fractional bandwidth of approximately 29% were fabricated on lithium niobate (LiNbO3) having a center frequency of 250 MHz and the filter has a processing gain of 49. A coupling of modes (COM) model is used to predict the experimental SAW filter response. Discussion of the filter design, analysis and measurements are presented. Results are shown for operation in a matched filter correlator for use in an UWB communication system and compared to predictions.M.S.E.E.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering MSEE
14
Stevens, Janet Emerson, and Tri T. Ha. "Trellis coded modulation applied to orthogonal signals." Thesis, Monterey, California. Naval Postgraduate School, 1993. http://hdl.handle.net/10945/24242.
Full text
15
Karlsson, Andreas. "Simulation of a CDMA system based on optical orthogonal codes." Thesis, Linköping University, Department of Electrical Engineering, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2300.
Full textAbstract:
To take advantage of the high speed in an optic fiber, one of the basic concept in fiber optic communication is to allow several users to simultaneously transmit data over the channel. One technique that provides multiple access is it fiber optic-code division multiple access (FO-CDMA). In FO-CDMA each user is assigned one or more signature sequences called codewords, which are subsets of a type of optical orthogonal code (OOC). The channel input/output consists of the superposition of several users codewords and at the receiver end an optical correlator extracts the information.
In the parallel code constructions, presented in this report, each user j is assigned a subset Cj from a code C. The subsets are disjoint and their union is the whole set C. A new way to map the information bits is to insert up to L zeros before each codeword from Cj and let this represent information aswell. This gives high rates for active users but an investigation is needed to ensure that this does not compromise the systems wanted property of sending information with a small probability of errors for all users. Therefore a simulation environment has been implemented in Matlab.
The result from these simulations shows that BER for the L parallel codes is acceptable and not much higher than for the traditional constructions. Because of the higher rate these construction should be preferred but an analysis if a hardware implementation is possible.
16
Isaksson, Erica. "Cardinality for optical orthogonal codes with variable length and weight." Thesis, Linköping University, Department of Electrical Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-7672.
Full textAbstract:
To let many users benefit from the high speed communication in an optical fiber, a way to share the channel is needed. One way to share the channel between the users is the multiple access technique of Code Division Multiple Access, CDMA. This technique is based on coding. By assigning the users different codewords, the receiver is able to distinguish the information sent from each user. One family of codes suitable to use in a fiber optic network is the constant weight Optical Orthogonal Codes, OOC.
To influence the users interference tolerability it is possible to assign the users codewords of the same length but with different weights. By letting the users have codewords of different length it is possible to have different data rates in the system. These two versions of optical orthogonal codes, with variable length and weight, are investigated in this thesis for their cardinality. The variable weight and variable length codes were created by combining optical orthogonal codes with different parameters.
I have found that for variable length OOC:s of weight 2 it seems to be possible to increase the cardinality of a code, but for codes with higer weights than that, it is better that all users are assigned codewords of the same length. But since an upper bound for the cardinality of these types of codes has not been found, it is not possible to verify if this conclusion is correct. For variable weight OOC:s it is found that it is only possible to increase the cardinality of small, not optimal, codes. For codes including many codewords it is rarely possible to include more codewords without breaking the conditions on cross correlation between the codewords.
17
Lin, Rui. "Hybrid ARQ Schemes for Non-orthogonal Space-time Block Codes." Thesis, University of Canterbury. Electrical and Computer Engineering, 2007. http://hdl.handle.net/10092/1183.
Full textAbstract:
Automatic Repeat-reQuest (ARQ) schemes are extensively used in communication systems and computer networks to achieve reliable transmission. Using space-time codes (STCs) with multiple input multiple output (MIMO) or multiple input single output (MISO) systems is an effective way to combat multipath fading, which is the most severe impairment for wireless communication systems. STCs are designed to use the rich scattering multipath environment provided by using multiple transmit antennas. The work done in this thesis focuses on the use of ARQ schemes with non-orthogonal space-time block codes (NOSTBCs) based on Reed Solomon codes. The truncated-selective ARQ (TS-ARQ) scheme is considered and three novel hybrid ARQ (HARQ) schemes are proposed. Simulation results reveal that, compared to using TS-ARQ with orthogonal space-time block codes (OSTBCs), using NOSTBCs with any of the three proposed HARQ schemes can provide significant gains in terms of dropped packet rate and spectral efficiency at the cost of increased decoding complexity. The performance can be further improved by using the water filling principle to adaptively allocate transmit power among transmit antennas.
18
Mustapha, Mazlyn Mona. "Non-coherent optical fibre-based CDMS using optical orthogonal codes." Thesis, Cranfield University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435041.
Full text
19
Guan, Karen Min 1978. "Quadrature amplitude modulated codes for orthogonal frequency division multiplexing applications." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/87226.
Full text
20
Karacayir, Murat. "Space-time Codes." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612028/index.pdf.
Full textAbstract:
The phenomenon of fading constitutes a fundamental problem in wireless communications. Researchers have proposed many methods to improve the reliability of communication over wireless channels in the presence of fading. Many studies on this topic have focused on diversity techniques. Transmit diversity is a common diversity type in which multiple antennas are employed at the transmitter. Space-time coding is a technique based on transmit diversity introduced by Tarokh et alii in 1998.
In this thesis, various types of space-time codes are examined. Since they were originally introduced in the form of trellis codes, a major part is devoted to space-time trellis codes where the fundamental design criteria are established. Then, space-time block coding, which presents a different approach, is introduced and orthogonal spacetime block codes are analyzed in some detail. Lastly, rank codes from coding theory
are studied and their relation to space-time coding are investigated.
21
Sevelimedu, Veeravalli Vinodh. "Study of MIMO, orthogonal codes and core operator architecture design for ML decoder." Thesis, Linköping University, Department of Electrical Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-10155.
Full textAbstract:
In the high-end research process of wireless systems and in the race for the development of the new technologies, MIMO (Multiple Input, Multiple Output) is getting more attention now days. It has a high potential usage in the 3G and 4G communications and beyond. The MIMO based system has got the ability to increase the data throughput in spectrum-limited conditions. With the increase and complexity of wireless applications, the spectrum efficiency improvement in the physical layer will be saturated. MIMO is predicted to be one of the major features for the next generation wireless networking. This thesis work is a part of an ongoing project of the Generic MIMO decoder design carried out at the research laboratory, LESTER at Lorient, France. I was involved in the study of MIMO concepts, orthogonal and Space-time codes and later involved in the design and optimization of the architecture for the core operator for the ML decoder used in the reception of the MIMO system,which is presented in this report work.
22
Sawa, Masanori. "Optical Orthogonal Signature Pattern Codes with Maximum Collision Parameter 2 and Weight 4." IEEE, 2010. http://hdl.handle.net/2237/14501.
Full text
23
Kusuma, Josephine. "Z4-codes and their gray map images as orthogonal arrays and t-designs." Thesis, Queen Mary, University of London, 2009. http://qmro.qmul.ac.uk/xmlui/handle/123456789/566.
Full textAbstract:
This thesis discusses various connections between codes over rings, in par- ticular linear Z4-codes and their Gray map images as orthogonal arrays and t-designs. It also introduces the connections between VC-dimension of binary codes and the strengths of the codes as orthogonal arrays. The second chapter concerns codes over rings. It is known that if we have a matrix A over a eld F, whose rows form a linear code, such that any t columns of A are linearly independent then A is an orthogonal array of strength t. I shall begin with generalising this theorem to any nite commutative ring R with identity. The case R = Z4 is particularly important, because of the Gray map, an isometry from Zn 4 (with Lee weight) to Z2n 2 (with Hamming weight). I determine further connections that exist between the strength of a linear code C over Z4 as an orthogonal array, the strength of its Gray map image as an orthogonal array and the minimum Hamming and Lee weights of its dual C?. I also nd that the strength of a binary code as an orthogonal array is less than or equal to its strong VC-dimension. The equality holds for linear binary codes. Furthermore, the lower bound is also determined for the strength of the Gray map image of any linear Z4-code. 4 Moreover, I show that if a code over any alphabet is an orthogonal array with a certain constraint then the supports of the codewords of some Hamming weight form a t-design. Furthermore, I prove that if a linear Z2- code satis es the t-mixture condition, then such a code is an orthogonal array of strength t. I then investigate if such connection also exists for non- linear Gray map images of linear Z4-codes, and prove that it does for some values t.
24
Welling, Kenneth. "Coded Orthogonal Frequency Division Multiplexing for the Multipath Fading Channel." International Foundation for Telemetering, 1999. http://hdl.handle.net/10150/608525.
Full textAbstract:
International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, NevadaThis paper presents a mathematical model for Coded Orthogonal Frequency Division Multiplexing (COFDM) in frequency selective multipath encountered in aeronautical telemetry. The use of the fast Fourier transform (FFT) for modulation and demodulation is reviewed. Error control coding with interleaving in frequency is able to provide reliable data communications during frequency selective multipath fade events. Simulations demonstrate QPSK mapped COFDM performs well in a multipath fading environment with parameters typically encountered in aeronautical telemetry.
25
Potter, Chris, Kurt Kosbar, and Adam Panagos. "Hardware Discussion of a MIMO Wireless Communication System Using Orthogonal Space Time Block Codes." International Foundation for Telemetering, 2008. http://hdl.handle.net/10150/606194.
Full textAbstract:
ITC/USA 2008 Conference Proceedings / The Forty-Fourth Annual International Telemetering Conference and Technical Exhibition / October 27-30, 2008 / Town and Country Resort & Convention Center, San Diego, CaliforniaAlthough multiple-input multiple-output (MIMO) systems have become increasingly popular, the existence of real time results to compare with those predicted by theory is still surprisingly limited. In this work the hardware description of a MIMO wireless communication system using orthogonal space time block codes (OSTBC) is discussed for two antennas at both the transmitter and receiver. A numerical example for a frequency flat time correlated channel is given to show the impact of channel estimation.
26
Deng, Yunfei 1974. "Simplified decoding for a Quasi-Orthogonal space-time code family." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=81534.
Full textAbstract:
This thesis considers simplified decoding for a type of full-rate non-orthogonal complex space-time block codes (STBCs) over Rayleigh fading channels. More precisely, we propose a decision feedback symbol-by-symbol decoding algorithm for the Quasi-Orthogonal code family, that comprises the Quasi-Orthogonal code and the Improved Quasi-Orthogonal code, by using the QR decomposition. Compared to optimal joint decoding, this algorithm significantly reduces complexity. For performance evaluations of the simplified decoding algorithm for the Quasi-Orthogonal code family over Rayleigh fading channels, we derive upper and lower bounds for symbol error rate. Furthermore, by using high SNR asymptotics we investigate the diversity orders provided by different decoding algorithms. The analysis shows that because of the relative constellation rotation, the diversity order provided by optimal decoding for the Improved Quasi-Orthogonal code is 4. Also, because of the error propagation in the decision feedback, the diversity order provided by the simplified decoding for the Improved Quasi-Orthogonal code is reduced to 2. All analytical results match well the associated computer simulations. Finally, we compare the performances of the simplified and optimal decoding for the Improved Quasi-Orthogonal code over correlated Rayleigh fading channels by using the "one-ring" channel model. Through computer simulations we show that the relative performance loss between the simplified and optimal decoding decreases as channel correlation increases. Therefore, the simplified decoding algorithm is suitable for highly spatially correlated Rayleigh fading channels.
27
Pramaita, Nyoman. "Hybrid orthogonal code sequences for high-density synchronous CDMA systems." Thesis, Liverpool John Moores University, 2014. http://researchonline.ljmu.ac.uk/4592/.
Full textAbstract:
One of the primary tasks of the mobile system designers in order to support high density of devices in a CDMA system is to create a code sequence with a capacity for large number of spreading code sequences having low cross-correlation values between them, in order to ensure accommodation of large number of users and to minimise the effect of multiple access interference. In this research, the design for a novel hybrid orthogonal very large set (HOVLS) code sequence is proposed for high density mobile application scenarios. The design and development of both fixed and variable spreading factor code sequences are presented in this thesis. Both type of code sequences have been implemented via simulation using Matlab/Simulink. The performance of the code sequences has been evaluated and compared with that of existing code sequences. The proposed code sequences are more advantageous for high density mobile networks. The unique feature of the fixed length HOVLS code sequence is that its ACF, CCF, and BER performances are similar to that of orthogonal Gold code sequence and orthogonal m-sequence under Rayleigh flat and frequency selective fading channel conditions while having a significantly higher capacity than those orthogonal code sequences. The proposed HOVLS code sequence could support 134 different cells which is more than twice than that of orthogonal Gold code sequence and orthogonal m-sequence. To the knowledge of the author, this is the largest reported family size in the literature for an orthogonal code sequence for CDMA applications. In order to support variable data rate, fixed length HOVLS code sequence was developed into orthogonal variable spreading factor code sequence. It is shown that the proposed OVSF code sequence has slightly better CCF than those of OVSF Gold code sequence and m-sequence in terms of CM (correlation margin). The ACF of the proposed OVSF code sequence is similar to those of OVSF Gold code sequence and m-sequence. The proposed OVSF code sequence possesses comparable BER performance to those of orthogonal Gold code sequence and orthogonal m-sequence under flat fading channel condition. Whereas, the BER performance of the proposed OVSF code sequence is slightly better than that of Gold code sequence and OVSF m-sequence under frequency selective fading channel. Therefore, the proposed HOVLS code sequence is appropriate code sequence in CDMA systems than those of orthogonal Gold code sequence and orthogonal m-sequence for both fixed and variable rate high density network applications.
28
Willis, Julian C. W. "Developing new orthogonal tRNA/synthetase pairs for genetic code expansion." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/274057.
Full text
29
Hesse, Matthias. "L2-orthogonal space-time code design for continuous phase modulation." Nice, 2010. http://www.theses.fr/2010NICE4008.
Full textAbstract:
Orthogonal Space-Time block codes (STBC) have been a popular way to implement wireless communications systems with full diversity and simple decoupled maximum-likelihood decoding. However, all these codes rely on pointwise orthogonality which leads to a well-known degradation of data rate for more than two antennas. In this thesis, we introduce the concept of L2-orthogonality for non-linear Space-Time codes (STC). Our approach generalizes code design based on pointwise orthogonality. Hence, we are able to derive new codes with the same advantages as pointwise orthogonal STBC, i. E. Low decoding complexity and diversity gain. At the same time, we are no longer limited by the restrictions of pointwise orthogonal codes, namely the reduction in data rate. Actually, we show how to construct full rate codes for any arbitrary number of transmit antennas. More precisely, a family of codes for continuous phase modulation (CPM) is detailed. The L2-orthogonality of these codes is ensured by a bank of phase correction functions which maintains the phase continuity but also introduces frequency offsets. We prove that these codes achieve full diversity and have full rate. Moreover, these codes don't put any restriction on the CPM parametersLes codes spatio-temporels orthogonaux par blocs (OSTBC) sont devenus populaires en ce qu'ils permettent de construire des systèmes de communications sans-fil à diversité maximale et à décodage simplifié par maximum de vraisemblance découplé. Cependant, ces codes reposent en général sur une orthogonalité ponctuelle, ce qui entraîne une dégradation bien connue du débit de transmission pour les systèmes à plus de deux antennes d'émission. Nous introduisons dans cette thèse le concept d'orthogonalité L2 pour les codes spatio-temporel (STC). Cette approche permet de généraliser naturellement la propriété d'orthogonalité ponctuelle pour des systèmes à codages spatio-temporels non-linéaires. Il devient alors possible de construire de nouveaux systèmes multi-antennes (MIMO) à faible complexité de décodage et gain de diversité maximal. De plus, contrairement aux systèmes reposant sur des codes linéaires orthogonaux, ces nouveaux systèmes ne présentent plus de limitation du débit de transmission pour plus de deux antennes. Nous détaillons la construction générale de diverses familles de codes spatio-temporels L2 à débit maximal reposant sur des modulations de phase continue (CPM) et ceci pour n'importe quel nombre d'antennes d'émission. L'orthogonalité L2 des systèmes construits est obtenue par un banc de fonctions de correction de phase qui induit la diversité par décalage en fréquence tout en maintenant la continuité de la phase pour chaque antenne. L'étude de ces codes permet de démontrer que les systèmes MIMO à décodage simplifié ainsi obtenus sont à diversité maximale et débit optimal. Enfin, notons que la construction de ces codes n'introduit aucune contrainte supplémentaire sur les paramètres des modulations de phase continue utilisées
30
Saldanha, Nancy. "Modeling, design and fabrication of orthogonal and psuedo-orthogonal frequency coded SAW wireless spread spectrum RFID sensor tags." Doctoral diss., University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5025.
Full textAbstract:
Surface acoustic wave (SAW) sensors offer a wireless, passive sensor solution for use in numerous environments where wired sensing can be expensive and infeasible. Single carrier frequency SAW sensor embodiments such as delay lines, and resonators have been used in single sensor environments where sensor identification is not a necessity. The orthogonal frequency coded (OFC) SAW sensor tag embodiment developed at UCF uses a spread spectrum approach that allows interrogation in a multi-sensor environment and provides simultaneous sensing and sensor identification. The SAW device is encoded via proper design of multiple Bragg reflectors at differing frequencies. To enable accurate device design, a model to predict reflectivity over a wide range of electrode metallization ratios and metal thicknesses has been developed and implemented in a coupling of modes (COM) model. The high coupling coefficient, reflectivity and temperature coefficient of delay (TCD) of YZ LiNbO[sub3] makes it an ideal substrate material for a temperature sensor, and the reflectivity model has been developed and verified for this substrate. A new concept of pseudo-orthogonal frequency coded (POFC) SAW sensor tags has been investigated, and with proper design, the POFC SAW reduces device insertion loss and fractional bandwidth compared to OFC. OFC and POFC sensor devices have been fabricated at 250 MHz and 915 MHz using fundamental operation, and 500 MHz and 1.6 GHz using second harmonic operation. Measured device results are shown and compared with the COM simulations using the enhanced reflectivity model. Additionally, the first OFC devices at 1.05 GHz were fabricated on 128[superscript o] YX LiNbO[sub3] to explore feasibility of the material for future use in OFC sensor applications. Devices at 915 MHz have been fabricated on YZ LiNbO[sub3] and integrated with an antenna, and have then been used in a transceiver system built by Mnemonics, Inc. to wirelessly sense temperature.; The first experimental wireless POFC SAW sensor device results and predictions will be presented.ID: 029809657; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2011.; Includes bibliographical references (p. 148-152).
Ph.D.
Doctorate
Electrical Engineering and Computer Science
Engineering and Computer Science
31
Santos, Bianca Maria. "SAW REFLECTIVE TRANSDUCERS AND ANTENNAS FOR ORTHOGONAL FREQUENCY CODED SAW SENSORS." Master's thesis, University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3433.
Full textAbstract:
Passive sensors that vary its impedance per measured parameter may be used with surface acoustic wave (SAW) reflective transducers (SRT) for wireless acquisition of the measurand. The device is composed of two transducers, where one, which may be attached to an antenna, is used to launch the wave within the device substrate, and the other is where the sensor load is attached to. The latter is able to reflect the incident wave. How much power is reflected is determined by the attached sensor load. Amplitude variations as well as peak frequency variations of the SRT reflectivity response are explored in this thesis. SAW passive temperature sensors with an orthogonal frequency coded (OFC) time response were previously investigated and prove to be ideal for use in harsh environments. Each sensor is distinguishable from the other due to the OFC code embedded within its time response. However, this coding technique poses a difficulty in designing antennas for the sensor due to its inherently wide bandwidth, and capacitive, non-uniform input impedance. This work covers antenna design and testing for the 250MHz wireless temperature acquisition prototype with a 28% fractional bandwidth, and for the 912MHz system which has 10% fractional bandwidth. Apart from the tag, antennas for the transmitter and receiver were designed for 50 Ohm matching with the required bandwidth maintained. Wireless temperature acquisition runs for the 250MHz prototype were successfully performed and show good agreement with measurements made by a thermocouple. Since a transceiver for the 912MHz system is not complete, the performance of the antennas was gauged by observing the signal transmitted wirelessly by the SAW tag and by comparing this with the sensor time response measured directly by a vector network analyzer.M.S.E.E.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering MSEE
32
Rende, Deniz. "Bit-interleaved space-frequency coded modulation for orthogonal frequency-division multiplexing systems." [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0006420.
Full text
33
Renoult, Adrien Fijalkow Inbar. "Analyse des performances d'un système multi-utilisateurs OFDM codé sans accès orthogonal." [s.l.] : [s.n.], 2008. http://biblioweb.u-cergy.fr/theses/05CERG0264.pdf.
Full text
34
Alder, Frank A. "Symbol assignment and performance of simplex signaling in high dimensional trellis-coded modulation." Ohio : Ohio University, 1998. http://www.ohiolink.edu/etd/view.cgi?ohiou1177008035.
Full text
35
Ilunga, Lou. "Adaptive, Turbo-coded OFDM." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/34578.
Full textAbstract:
Wireless technologies, such as satellite, cellular, and wireless internet are now commercially driven by ever more demanding consumers, who are ready for seamless integration of communication networks from the home to the car, and into the office. There is a growing need to quickly transmit information wirelessly and accurately. Engineers have already combine techniques such as orthogonal frequency division
multiplexing (OFDM) suitable for high data rate transmission with forward error correction (FEC) methods over wireless channels.
In this thesis, we enhance the system throughput of a working OFDM system by adding turbo coding and adaptive modulation (AD). Simulation is done over a time varying, frequency selective Rayleigh fading channel. The temporal variations in the simulated wireless channel are due to the presence of Doppler, a sign of relative motion between transmitter and receiver. The wideband system has 48 data sub-channels, each is individually modulated according to channel state information acquired during the previous burst. The end goal is to increase the system throughput while maintaining system performance under a bit error
rate (BER) of 10-2. The results we obtained are preliminary. The lack of resources prevented us from producing detailed graphs of our findings.
Master of Science
36
Rice, Michael, and Kenneth Welling. "CODED OFDM FOR AERONAUTICAL TELEMETRY." International Foundation for Telemetering, 2000. http://hdl.handle.net/10150/606496.
Full textAbstract:
International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, CaliforniaThree Quadrature Phase Shift Keying (QPSK) mapped COFDM systems demonstrating a continuum of complexity levels are simulated over an evolving three ray model of the multipath fading channel with parameters interpolated from actual channel sounding experiments. The first COFDM system uses coherent QPSK and convolutional coding with interleaving in frequency, channel equalization and soft decision decoding; the second uses convolutional coding with interleaving in frequency, Differential Phase Shift Keying (DPSK) and soft decision decoding; the third system uses a quaternary BCH code with DPSK mapping and Error and Erasure Decoding (EED). All three systems are shown to be able to provide reliable data communication during frequency selective fade events. Simulations demonstrate QPSK mapped COFDM with reasonable complexity performs well in a multipath frequency selective fading environment under parameters typically encountered in aeronautical telemetry.
37
van, Wyk Jacques Herman. "Design of a Gigabit DSL modem using Super Orthogonal Complete Complementary Codes for MUI-free communication." Thesis, University of Pretoria, 2017. http://hdl.handle.net/2263/61097.
Full textAbstract:
The primary problem addressed in this thesis is to develop a Multi-carrier Code Division Multiple Access (MC-CDMA) Digital Subscriber Line (DSL) modem, capable of delivering 1 Gbps aggregated throughput over a 200 m single twisted-pair of 0.5 mm copper wire. A secondary problem is too much self-interference within Digital Subscriber Line (DSL) systems. Self-interference is defined as the disturbance or interference that is created by similar DSL technology (i.e. one VDSL service on another VDSL service) operating within the same frequency band. The interference, referred to as Crosstalk is due to magnetic cross-coupling of signals between adjacent twisted pairs. Far end crosstalk (FEXT) for short loops is still a huge problem. Current techniques like Vectoring makes use of pre-coding in downstream transmission and makes use of Multi-user Detection and interference Cancellation (MUD-IC) in upstream transmission. Overall these techniques (pre-coding and MUD-IC) have a high computational overhead. Using Super Orthogonal Complete Complementary (SOCC) spreading codes the effect of crosstalk is mitigated, since the SOCC spreading/despreading process inherently provide IC and does not require overhead for pre-coding and MUD-IC.
The designed GDSL modem provides Multi-user interference (MUI)-free communication in a highly crosstalk dominated environment (Near end crosstalk and Far-end crosstalk) by incorporating Super Orthogonal Complete Complementary (SOCC) spreading into the existing xDSL modem architecture.
A novel code allocation algorithm was also developed to provide all users with equal transfer ratios (i.e. transferred bits to offered bits), even with bad line profiles and a high amount of offered bits. Implementation and simulation of existing network characteristics, including attenuation, Near-end Crosstalk (NEXT) and Far-end Crosstalk (FEXT) used ITU and NIPPC standards as guidelines.
1 Gbps aggregate throughput was obtained for the GDSL system over a single pair of 0.5 mm diameter copper wire over a distance of 190 m with only GDSL modems present, or 185 m to 148 m, depending on whether ADSL2+ or VDSL2 Profile 30a bypass profiles are implemented. Performance analysis in a practical MIMO crosstalk environment showed that the GDSL system have acceptable BER performance for a fully loaded system of 64 users, even for very short loops severe FEXT).Thesis (PhD) --University of Pretoria, 2017.
Electrical, Electronic and Computer Engineering
PhD
Unrestricted
38
Sarvepalli, Pradeep Kiran. "Quantum stabilizer codes and beyond." Diss., Texas A&M University, 2008. http://hdl.handle.net/1969.1/86011.
Full textAbstract:
The importance of quantum error correction in paving the way to build a practical
quantum computer is no longer in doubt. Despite the large body of literature in quantum
coding theory, many important questions, especially those centering on the issue of "good
codes" are unresolved. In this dissertation the dominant underlying theme is that of constructing
good quantum codes. It approaches this problem from three rather different but
not exclusive strategies. Broadly, its contribution to the theory of quantum error correction
is threefold.
Firstly, it extends the framework of an important class of quantum codes - nonbinary
stabilizer codes. It clarifies the connections of stabilizer codes to classical codes over
quadratic extension fields, provides many new constructions of quantum codes, and develops
further the theory of optimal quantum codes and punctured quantum codes. In particular
it provides many explicit constructions of stabilizer codes, most notably it simplifies
the criteria by which quantum BCH codes can be constructed from classical codes.
Secondly, it contributes to the theory of operator quantum error correcting codes also
called as subsystem codes. These codes are expected to have efficient error recovery
schemes than stabilizer codes. Prior to our work however, systematic methods to construct
these codes were few and it was not clear how to fairly compare them with other classes of
quantum codes. This dissertation develops a framework for study and analysis of subsystem
codes using character theoretic methods. In particular, this work established a close
link between subsystem codes and classical codes and it became clear that the subsystem codes can be constructed from arbitrary classical codes.
Thirdly, it seeks to exploit the knowledge of noise to design efficient quantum codes
and considers more realistic channels than the commonly studied depolarizing channel.
It gives systematic constructions of asymmetric quantum stabilizer codes that exploit the
asymmetry of errors in certain quantum channels. This approach is based on a Calderbank-
Shor-Steane construction that combines BCH and finite geometry LDPC codes.
39
Spyridakis, Georgios George. "Antenna reduction techniques in MIMO systems and ad-hoc networks." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/antenna-reduction-techniques-in-mimo-systems-and-adhoc-networks(d6b8e0ab-cd13-4c65-9be6-efd9e22c7e39).html.
Full textAbstract:
In this thesis, an antenna reduction technique in Multiple Input Multiple Output (MIMO) systems, which is called Code Shift Keying (CSK) Modulation, is introduced. With the use of Walsh Hadamard orthogonal spreading codes, we overcome the biggest drawback of conventional Spatial Modulation (SM) which is the antenna index estimation errors due to channel correlation. Also SM fails to perform in non normalised channel conditions. The combination of orthogonal spreading codes and antenna devices, as a means to convey information at the receiver, results in a remarkable performance improvement at the receiver.Moreover, an improved scheme that uses half the amount of spreading codes so as to represent the total number of information bits has been introduced leading to an important reduction in bandwidth usage. By maintaining the net spreading levels of the system we attain remarkable performance improvements.A technique called Polarisation Assisted Space Shift Keying Modulation (PASSK) has also been proposed which manages to exploit the polarisation domain and it is able to outperform the conventional SM technique as well as the Maximal Ratio Receiver Combine (MRRC) and Vertical-Bell Laboratories Layered Space-Time (V-BLAST) schemes. A new precoding scheme that manages to either eliminate or exploit the cross polarisation effects has also been proposed as a complementary study of the PASSK scheme.As modern and future communications show a rising demand for higher data transmission rates, network coding is increasingly incorporated in wireless communication standards. In harmonisation with this trend, this thesis discusses the main state-of-art network coding schemes. The contribution here includes a number of innovative schemes that are able to further increase throughput. Finally, the employment of network coding is discussed in conjunction with CSK Modulation resulting to further improvement in terms of throughput as well as Bit Error Rate (BER) performance at the cost of increased bandwidth usage.
40
Larhzaoui, Thomas. "Fiabilisation de la technologie courant porteur en ligne en vue de piloter des actionneurs d’aéronefs." Thesis, Rennes, INSA, 2014. http://www.theses.fr/2014ISAR0009/document.
Full textAbstract:
Dans le cadre de l’avion plus électrique, les avionneurs cherchent à remplacer les commandes de vol hydrauliques par des commandes de vol électriques, avec pour intérêt de diminuer le poids, et d’améliorer la flexibilité des équipements aéronautiques. Sachant que sur un A380, la distance cumulée pour les câbles peut atteindre plus de 500 km, la solution consistant à faire cohabiter les transmissions de données et de puissances au sein de mêmes câbles grâce à la technologie CPL pourrait contribuer à réduire la masse de câble dans un avion. Cependant les câbles de puissance n’ont pas été dimensionnés pour transmettre un signal informationnel, et les équipements présents sur le réseau sont source de bruits. Dans ce contexte nous souhaitons montrer la faisabilité d’une transmission CPL soumise aux contraintes avioniques tout en respectant les normes aéronautiques. La première partie des travaux a consisté à mesurer le canal de propagation sur un banc de test représentatif d’un environnement aéronautique. Le canal de propagation est composé de deux coupleurs de type inductif ou capacitif dont le but est de connecter les câbles de télécommunication au réseau de puissance et d’une paire bifilaire torsadée de puissance d’une longueur de 32 m représentative d’un réseau HVDC ±270 V. Nous avons alors testé trois architectures différentes : l’architecture point-À-Point avec coupleur capacitif, l’architecture point-À-Point avec coupleur inductif et l’architecture point-À-Multipoints avec coupleur inductif. Le but de ces mesures a été d’évaluer la fonction de transfert du canal sur la bande [1 ; 100] MHz. Nous avons alors calculé les éléments caractéristiques du canal comme la bande de cohérence et l’étalement des retards. Après la caractérisation du canal de propagation, nous avons choisi et dimensionné les algorithmes de traitement du signal au regard des spécifications aéronautiques à savoir : un débit utile de 10 Mbit/s, un temps de latence de 167-334 μs, un TEB de 10-12 et le respect du gabarit de la DO-160 en émission conduite. Au regard de la fonction de transfert du canal, nous avons choisi d’utiliser l’OFDM comme technique de transmission. Ainsi, à l’aide de la caractérisation du canal de propagation nous avons au cours d’une étude paramétrique défini les paramètres de la transmission OFDM au regard des spécifications de débit et de temps réel. Dans un second temps, nous avons implanté les paramètres OFDM ainsi que la modélisation du canal de propagation dans une chaine de transmission Matlab. Cette chaine nous a alors permis de vérifier les paramètres issues de l’étude paramétrique ainsi que de définir le système de codage de canal (Reed-Solomon et code convolutif) pour respecter les spécifications aéronautiques. La dernière partie de cette thèse a consisté en l’étude du système de synchronisation. Du fait de la stabilité du canal de propagation, nous avons considéré une synchronisation fine du système lors d’une phase d’initialisation puis nous nous somme focalisé sur le dimensionnement d’un système de suivi dans le but de corriger le décalage de fenêtre FFT dû au défaut de fréquence d’échantillonnage. Pour limiter les pertes de débit lors de la phase de suivi, nous avons proposé une estimation de l’erreur de fréquence d’échantillonnage sur la phase des données reçues sur une période de 20 symboles OFDMIn the new aircrafts, hydraulic flight control systems are replaced by electric flight control systems. The main interests are a better flexibility of the aeronautical equipments and a decrease in maintenance costs and construction costs, but the major problem is the increasing of the wires length. In order to decrease this length, it has been proposed to use power line communications (PLC) technology for flight control systems. The decrease of wire will first decrease aircraft weight and therefore the consumption of kerosene and on the other hand will simplify maintenance and construction. The first part of this work is the measurement and the characterisation of the propagation channel on an aeronautic test bench (with HVDC supply and loads). This channel is composed of two couplers (inductive or capacitive) in order to connect the telecommunication system on the power wires with galvanic isolation and one twisted pair of 32 m longs. We have tested three architectures: the point-To-Point architecture with capacitive coupler, the point-To-Point architecture with inductive coupler and the point-To-Multipoint architecture with inductive coupler. The purpose of these measurements is to measured the transfer function on the [1 ; 100] MHz bandwidth. Then, we have computed the channel parameters like the coherence bandwidth and the delay spread. The second step was the design of the signal processing algorithm in order to satisfy the aeronautical specifications: a useful bite rate of 10 Mbit/s, a latency of 167- 334 μs, a BER of 10-12 and the respect of the DO-160 gauge in conducted emissions. For the transmissions, we have chosen the OFDM technology which has been use with success in other PLC systems. With the channel characterization, we have proposed a parametric study in order to define the OFDM parameters to satisfy the bite rate and the real time constraints. After, we compute digital simulations with Matlab to check the OFDM parameters. With these simulations, we have also defined the channel coding parameters (Reed-Solomon and convolutional coding) to satisfy the aeronautical specifications. The last part of this study was the design of the synchronisation system. Because of the channel stability, we considered a precise synchronisation after an initialisation period. Then, we focus on the estimation of the FFT shift, due to the sampling frequency shift, during a following-Up period. In order to avoid the decrease of the latency and the bitrate due to the pilot symbols or pilot sub-Carriers insertion, we proposed to correct the FFT shift with the receive data thanks to the maximal likelihood algorithm
41
Wilson, William. "Multifunctional Orthogonally-Frequency-Coded Saw Strain Sensor." VCU Scholars Compass, 2013. http://scholarscompass.vcu.edu/etd/3157.
Full textAbstract:
A multifunctional strain sensor based on Surface Acoustic Wave (SAW) Orthogonal Frequency Coding (OFC) technology on a Langasite substrate has been investigated. Second order transmission matrix models have been developed and verified. A new parameterizable library of SAW components was created to automate the layout process. Using these new tools, a SAW strain sensor with OFC reflectors was designed, fabricated and tested. The Langasite coefficients of velocity for strain (γS = 1.699) and Temperature (γT = 2.562) were experimentally determined. The strain and temperature characterization of this strain sensor, along with the coefficients of velocity, have been used to demonstrate both the ability to sense strain and the capability for temperature compensation. The temperature-compensated SAW OFC strain sensor has been used to detect anomalous strain conditions that are indicators of fastener failures during structural health monitoring of aircraft panels with and without noise on a NASA fastener failure test stand. The changes in strain that are associated with single fastener failures were measured up to a distance of 80 cm between the sensor and the removed fastener. The SAW OFC strain sensor was demonstrated to act as an impact sensor with and without noise on the fastener failure test stand. The average measured signal to noise ratio (SNR) of 50, is comparable to the 29.1 SNR of an acoustic emission sensor. The simultaneous use of a high pass filter for impact detection, while a low pass filter is used for strain or fastener failure, demonstrates the multifunctional capabilities of the SAW OFC sensor to act as both as a fastener failure detector and as an impact detector.
42
Lee, King F. "Space-time and space-frequency coded orthogonal frequency division multiplexing transmitter diversity techniques." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/14981.
Full text
43
Owojaiye, Gbenga Adetokunbo. "Design and performance analysis of distributed space time coding schemes for cooperative wireless networks." Thesis, University of Hertfordshire, 2012. http://hdl.handle.net/2299/8970.
Full textAbstract:
In this thesis, space-time block codes originally developed for multiple antenna systems are extended to cooperative multi-hop networks. The designs are applicable to any wireless network setting especially cellular, adhoc and sensor networks where space limitations preclude the use of multiple antennas. The thesis first investigates the design of distributed orthogonal and quasi-orthogonal space time block codes in cooperative networks with single and multiple antennas at the destination. Numerical and simulation results show that by employing multiple receive antennas the diversity performance of the network is further improved at the expense of slight modification of the detection scheme. The thesis then focuses on designing distributed space time block codes for cooperative networks in which the source node participates in cooperation. Based on this, a source-assisting strategy is proposed for distributed orthogonal and quasi-orthogonal space time block codes. Numerical and simulation results show that the source-assisting strategy exhibits improved diversity performance compared to the conventional distributed orthogonal and quasi-orthogonal designs.Motivated by the problem of channel state information acquisition in practical wireless network environments, the design of differential distributed space time block codes is investigated. Specifically, a co-efficient vector-based differential encoding and decoding scheme is proposed for cooperative networks. The thesis then explores the concatenation of differential strategies with several distributed space time block coding schemes namely; the Alamouti code, square-real orthogonal codes, complex-orthogonal codes, and quasiorthogonal codes, using cooperative networks with different number of relay nodes. In order to cater for high data rate transmission in non-coherent cooperative networks, differential distributed quasi-orthogonal space-time block codes which are capable of achieving full code-rate and full diversity are proposed. Simulation results demonstrate that the differential distributed quasi-orthogonal space-time block codes outperform existing distributed space time block coding schemes in terms of code rate and bit-error-rate performance. A multidifferential distributed quasi-orthogonal space-time block coding scheme is also proposed to exploit the additional diversity path provided by the source-destination link.A major challenge is how to construct full rate codes for non-coherent cooperative broadband networks with more than two relay nodes while exploiting the achievable spatial and frequency diversity. In this thesis, full rate quasi-orthogonal codes are designed for noncoherent cooperative broadband networks where channel state information is unavailable. From this, a generalized differential distributed quasi-orthogonal space-frequency coding scheme is proposed for cooperative broadband networks. The proposed scheme is able to achieve full rate and full spatial and frequency diversity in cooperative networks with any number of relays. Through pairwise error probability analysis we show that the diversity gain of the proposed scheme can be improved by appropriate code construction and sub-carrier allocation. Based on this, sufficient conditions are derived for the proposed code structure at the source node and relay nodes to achieve full spatial and frequency diversity. In order to exploit the additional diversity paths provided by the source-destination link, a novel multidifferential distributed quasi-orthogonal space-frequency coding scheme is proposed. The overall objective of the new scheme is to improve the quality of the detected signal at the destination with negligible increase in the computational complexity of the detector.Finally, a differential distributed quasi-orthogonal space-time-frequency coding scheme is proposed to cater for high data rate transmission and improve the performance of noncoherent cooperative broadband networks operating in highly mobile environments. The approach is to integrate the concept of distributed space-time-frequency coding with differential modulation, and employ rotated constellation quasi-orthogonal codes. From this, we design a scheme which is able to address the problem of performance degradation in highly selective fading environments while guaranteeing non-coherent signal recovery and full code rate in cooperative broadband networks. The coding scheme employed in this thesis relaxes the assumption of constant channel variation in the temporal and frequency dimensions over long symbol periods, thus performance degradation is reduced in frequencyselective and time-selective fading environments. Simulation results illustrate the performance of the proposed differential distributed quasi-orthogonal space-time-frequency coding scheme under different channel conditions.
44
Burwell, Alex. "Experimental Testing and Evaluation of Orthogonal Waveforms for MIMO Radar with an Emphasis on Modified Golay Codes." University of Dayton / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1405701478.
Full text
45
Zhang, Jingtao. "Frequency Generalized MC-CDMA Systems and Performance over Multiband Channels and with Multiple Level Orthogonal (MLO) Codes." Ohio University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1289279214.
Full text
46
Fiers, Guillaume. "Synthèse orthogonale de poly(triazole amide)s contenant des séquences codées synthétiques ou naturelles." Thesis, Strasbourg, 2018. http://www.theses.fr/2018STRAF022.
Full textAbstract:
Les poly(triazole amide)s sont une classe de polymères à séquences définies synthétisés par une approche « AB+CD » itérative, chimiosélective et supportée. Cette stratégie permet de contrôler parfaitement la séquence des monomères, puisque les unités constitutives sont ajoutées une à une. De plus, la chimiosélectivité des réactions de couplage permet de s’affranchir d’étapes de déprotection. En outre, l’utilisation d’un support solide minimise également le temps d’expérimentation et facilite les étapes de lavage, réduisant donc le temps total de synthèse. Cette voie de synthèse a été utilisée pour la préparation de différents types de polymères fonctionnels. Premièrement, plusieurs oligomères comme des structures composées de chaînes alkyles ou PEG ont été préparées, contenant des séquences de monomères non naturels qui forment un code binaire. Ces produits ont été analysés grâce à deux techniques de séquençage : la spectrométrie de masse en tandem et l’analyse de chaînes uniques par les nanopores. Une synthèse sans cuivre de ce type d’oligomères a également été considérée. Enfin, une nouvelle classe d’acides xénonucléiques (XNAs), les peptide triazole nucleic acids (PTzNAs), a été synthétisée et étudiée. En particulier, les propriétés d’hybridation de ces polymères contenant des séquences génétiques ont été examinéesPoly(triazole amide)s are a class of sequence-defined polymers synthesized via a chemoselective iterative “AB+CD” approach on a solid support. This strategy allows to perfectly control the sequence of monomers, since the building blocks are added one by one. Moreover, the chemoselectivity of the coupling reactions enables to avoid the use of deprotection steps and to save time. In addition, the use of a solid support also minimizes the experiment time and facilitates the cleaning steps, thus reducing the total synthesis time. This synthesis pathway was used for the synthesis of different types of functional polymers. First of all, several oligomers such as structures based on alkyl or PEG chains were prepared, containing sequences of non-natural monomers that form a binary code. Those products were analyzed with two sequencing techniques: tandem mass spectrometry and nanopore single-chain analysis. A copper-free synthesis of this type of oligomers was also considered. Then, a new class of xeno nucleic acids (XNAs), peptide triazole nucleic acids (PTzNAs) was synthesized and studied. In particular, the hybridization properties of those natural sequence-containing polymers were investigated
47
Chye, Chia Boon. "Implementation and performance evaluation of WiMAX STC for OFDMA." Thesis, Monterey, California. Naval Postgraduate School, 2010. http://hdl.handle.net/10945/55198.
Full textAbstract:
Approved for public release; distribution is unlimited.The major driver for broadband wireless communications has been reliable, high-data rate services. In wireless communication, the multipath fading constitutes a bottleneck for increasing data rates and causes performance degradation. To combat fading, we can use diversity. Wireless systems with multiple antennas at the transmitter and receiver have much larger capacity in fading channels than standard wireless systems. The objective of this thesis is to investigate the transmission scheme provided by matrix A and B in the 802.16 standard and show how it can be implemented. The research focuses on using maximal-ratio combining (MRC) to demodulate the transmitted symbols. Modifications to the existing matrix by using more frequency bands were introduced; this reduces the number of transmitting antennas and uses fewer time slots to transmit the same number of symbols. The modulator and demodulator design is also discussed. The performance of orthogonal and non-orthogonal space time codes (STC) are evaluated.
Civilian
48
Varakantham, Indrasena. "Investigation of Generalized DSSS Under Multiple Access and Multipath." Cleveland State University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=csu1245214261.
Full text
49
Hassan, Mohamed Abdulla S. "Channel Estimation and Equalisation for Multicarrier Systems Employing Orthogonal Space-Time Block Code." Thesis, University of Newcastle Upon Tyne, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.519490.
Full text
50
Kanj, Khalil. "Orthogonal short codes for code division multiple access networks." Thesis, 1995. http://spectrum.library.concordia.ca/3851/1/MM05133.pdf.
Full text