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Dissertations / Theses on the topic 'Radio communication signals'
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Mansfield, Thomas Oliver. "Data communication signals of opportunity for navigation." Thesis, University of Plymouth, 2017. http://hdl.handle.net/10026.1/10169.
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Mobile devices with wireless networking capabilities are used in a wide range of environments. Geolocation information increases the value of the data generated by a device and is vital in the development of a wide range of applications from autonomous vehicles to the Internet of things. Systems that generate signals specifically for geolocation have become widely adopted but, due to fundamental constraints, lack coverage and accuracy in complex urban and indoor environments. In addition to this, the reliance on a single signal source is not desirable in many applications that value the integrity of the geolocation estimate. A direction of research aiming to improve geolocation in indoor and urban environments measures signals of opportunity in order to generate a more robust estimate. While this approach improves signal availability, the unpredictable nature of these variable and uncontrolled signals leads to poor geolocation estimates, which are typically not suitable for use in many applications. This project aims to improve on the accuracy, resilience and integrity of a geolocation estimate obtained from signal of opportunity measurements in indoor and urban environments while reducing hardware requirements. This has been achieved by efficiently coupling signals of opportunity within the radio environment with other system signals, such as those from an inertial measurement unit. Research has been carried out to optimise the coupling of these data sources resulting in techniques to allow the identification and removal of key error drivers from both the radio environment and other system sensors. This thesis proposes a specifically designed extended Kalman filter to improve on the signal coupling. The filter aims to optimise the accuracy of radio environment measurements while also providing the ability to identify signal error sources in urban and indoor environments, leading to both greater accuracy and resilience of the geo-location estimate. Further, the proposed extended Kalman filter may use the radio environment as a source of geolocation data. The ability of the filter to recognise and mitigate leading radio environment error sources such as multipath and interference allowed the design of filters to obtain detailed and accurate signal strength and time of arrival information. The thesis also presents a thorough set of simulation and modelling experiments to investigate and optimise the efficiency of the proposed solutions in a range of environments. Validation testing confirmed that in the urban and indoor environments, the average error of geo-location estimates has been reduced from 10 m to 3 m without improvement to the hardware surrounding infrastructure. The improvements presented in this thesis allow networked devices to improve the value of their data by incorporating the context that comes from increased geolocation accuracy and resilience. In turn, this allows the development of a wide range of new location based applications for mobile devises in indoor and urban environments.
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April, Eric. "Blind adaptive sensor-array processing techniques for extracting highly corrupted radio communication signals." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq20900.pdf.
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Lau, Hing-keung. "Pilot-symbol-aided techniques for spectrally efficient signals in multipath-fading channels /." Hong Kong : University of Hong Kong, 1997. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19669161.
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Slosman, Brian D. "Design of discrete time radio receiver for the demodulation of power-separated co-channel satellite communication signals." Thesis, Monterey, California: Naval Postgraduate School, 2013. http://hdl.handle.net/10945/37719.
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Approved for public release; distribution is unlimited<br>This thesis has two purposes: 1) to document the design of a discrete-time radio receiver for the coherent detection of a QPSK signal in the presence of additive white Gaussian noise; and 2) further research into the performance of representative receivers in the successive demodulation of power-separated, co-channel satellite communications signals. Several commercial companies are offering satellite modulators and demodulators that allow frequency reuse over satellite communications links. There are two methods to demodulate these co-channel signals. The first method requires a priori knowledge of one of the two signals linearly superimposed in the satellite downlink. With this knowledge, the known signal is cancelled using subtraction to reveal the unknown co-channel signal. A second method of recovering both signals is possible if adequate power separation of the two signals allows recovery of the strong signal. After recovery of the strong signal, the data can be re-modulated and then cancelled from the composite signal to reveal the weak signal. This method has the advantage of not requiring a priori information which widens the applications for layered modulation techniques to simplex, broadcast, and multi-cast network architectures.
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Pourbahri, Babak. "Erbium-doped fibre amplifiers and their effects on the phase noise of optical carriers and radio-over-fibre signals." Thesis, University of Kent, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369689.
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劉慶強 and Hing-keung Lau. "Pilot-symbol-aided techniques for spectrally efficient signals in multipath-fading channels." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1997. http://hub.hku.hk/bib/B31237198.
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Chen, Cheng. "Simultaneous transmission of baseband signal and in band RF signal." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708805.
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Chen, Wei. "Signal processing for optical performance monitoring and impairment mitigation." Connect to thesis, 2006. http://repository.unimelb.edu.au/10187/1713.
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Optical performance monitoring is essential for managing optical networks. One important quantity to monitor is the optical signal-to-noise ratio (OSNR). And in high bit rate fiber optical systems operating at 10 Gb/s or beyond, compensating optical impairments becomes important. In this thesis, we investigate OSNR monitoring using beat noise and present two new OSNR monitoring techniques. We propose an OSNR monitoring technique using uncorrelated beat noise and show by experiment for a 10 Gb/s system that in the OSNR range from 10 dB to 30 dB, the proposed OSNR monitoring scheme has a measurement error of less than 0.5 dB. Then, we propose and experimentally demonstrate for the first time an OSNR monitoring technique using beat noise for optical packet switched networks which performs monitoring on a packet basis. The response time of the OSNR monitor can be around 10 ns and the OSNR measurement error is found to be less than 0.6 dB for OSNR from 10 dB to 30 dB. We also explore chromatic dispersion and polarization-mode dispersion (PMD) mitigation using Viterbi equalization in 10 Gb/s nonreturn-to-zero differential phase-shift keying (NRZ-DPSK) and differential quadrature phase-shift keying (NRZ-DQPSK) systems. We show through simulations that using Viterbi equalizers improves the performance of NRZ-OOK, NRZ-DPSK and NRZ-DQPSK receivers. For NRZ-DQPSK receiver with a Viterbi equalizer, the chromatic dispersion tolerance is about 5048 ps/nm and the PMD tolerance is about 160 ps at 3 dB OSNR penalty.
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Sharif, Bayan. "Signal processing and optimisation algorithms for acoustic and radio communications." Thesis, University of Newcastle Upon Tyne, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627730.
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Chu, Xiaoli. "Ultra-wideband direct-sequence impulse radio wireless communications /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202005%20CHU.
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Hao, Wu, and Zheng Zhibin. "CDMA SATELLITE MOBILE COMMUNICATION SYSTEM MULTI-SIGNAL RECEIVING AND SOFTWARE IMPLEMENTATION." International Foundation for Telemetering, 2000. http://hdl.handle.net/10150/606499.
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International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California<br>This paper presents one new type CDMA multi-signal receiving protocol, which is suitable for satellite
mobile communication systems. Then it gives the principle analysis and describes the realization of
this protocol. Meanwhile, it gives the software protocol implementation scheme. From the long point
of view, it will more increase the system flexibility, which is easier to update; and will solve the
interoperability and integration application problems. Finally, the simulation results conclude that
software implementation of CDMA multi-signal receiving in satellite mobile communication system
is feasible, and it may be used in other wireless communication systems.
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Iversen, Alexander. "Novelty detection by auto-association with application to radio communication signal recognition." Thesis, Heriot-Watt University, 2007. http://hdl.handle.net/10399/76.
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Noel, Allen L. "Performance study of a Marine Expeditionary Force radio system." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA238486.
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Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, September 1990.<br>Thesis Advisor(s): Ha, Tri T. Second Reader: Myers, Glen A. "September 1990." Description based on title screen as viewed on March 22, 2010. DTIC Identifier(s): Marine Corps Equipment, Theses. Author(s) subject terms: VHF radio, HF radio, Single channel radio, Circuit switching, Voice Communication, Engset distribution. Includes bibliographical references (p. 63). Also available in print.
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Nabavi, Neda. "Digital Signal Processing in Coherent Optical Radio Over Fiber Systems." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36664.
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Coherent communication systems became practical with the advent of integrated electronic circuits capable of supporting Digital Signal Processing (DSP) at speeds compatible with line rates. Much of the complexity and expense of the functions required in a coherent receiver to compensate for optical channel uncertainties and impairments could be transferred to DSP algorithms. The aim of the research presented in this thesis is to develop radical breakthrough DSP algorithms and design new architectures for the digital coherent optical receiver within the RF-Cité system and optical fiber network supported distributed millimeter wave wireless antenna system.
The model of an optical channel is fundamental for understanding phase and polarization drift, chromatic dispersion, polarization mode dispersion and other drawbacks of the fiber optic systems in order for the signal processing algorithm to compensate these effects. In this thesis firstly an evaluation of the optical channel model that accurately describes the single mode fiber as a coherent transmission medium is reviewed through analytical, numerical and experimental analysis.
Secondly, an original approach to the design of a digital coherent optical receiver is proposed which can adapt to random time-varying state of polarization (SOP) for both the local oscillator and signal. To address the problem, two different methods of polarization diverse recovery of the modulation with carrier phase estimation and elimination of sign ambiguity are performed and verified by numerical simulations. The results show the accurate recovery of the modulation and error-free constellation demodulation.
Furthermore, inspired by former investigations, the theoretical analysis of a novel microwave photonic integrated circuit (MPIC) implementations of various building blocks used within the RF-Cité architecture is presented. The application of the proposed circuit in RoF systems is demonstrated by computer simulations using the Virtual Photonics Inc. software and OptiSuite packages. The performance of the proposed MPIC in a RoF system is assessed through advance modulation format techniques that have been employed in many wireless communication standards owing to their high spectral efficiency. In the DSP module, delay compensation is applied to synchronize the received signal, and the system performance is evaluated by measuring the error vector magnitude of the received signal using single-mode fiber. This scheme removes the temperature control requirement; an undesirable feature in terms of energy consumption considerations.
Also, a modified polarization demultiplexing algorithm is employed to classify the input polarizations that transmit two independent channels that are mixed randomly as the light is propagating in the optical fiber. This novel technique enables blind algorithms to accurately track polarization channel alignment, through achieving accurate polarization de-multiplexing obtained by numerical simulations and experiments.
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Truong, Tuyen Phong. "Simulation and compiler support for communication and mobility for environment sensing." Thesis, Brest, 2018. http://www.theses.fr/2018BRES0048/document.
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Les transmissions radio à longue portée et basse énergie ouvrent de nouveaux champs d'application pour les capteurs, en particulier pour la surveillance de l'environnement. Le protocole radio LoRa permet, par exemple, de connecter des capteurs à une distance pouvant aller jusqu'à dix kilomètres en ligne de visée. Cependant, la grande surface couverte amène plusieurs difficultés, telles que le placement spatial en regard de la topologie géographique, ou la variabilité de la latence des communications. Le positionnement dans I'environnement comporte également des contraintes liées à I'intérêt des points de mesure du phénomène physique. Les critères de conception de ces réseaux tranchent donc avec les méthodes existantes (disques) quand on s'attaque aux terrains complexes. Cette thèse décrit des techniques de simulation basées sur I'analyse géographique cellulaire pour calculer les couvertures radio à longue portée et déduire les caractéristiques radios dans ces situations. Comme la propagation radio n'est qu'un cas particulier de phénomènes physiques, on montre qu'une approche unifiée cellulaire permet de caractériser beaucoup de comportements physiques potentiels. Le cas des fortes pluies et des inondations est étudié. L'analyse de la géographie est réalisée en utilisant des outils de segmentation pour produire des systèmes cellulaires qui sont à leur tour traduits en code pour des calculs de haute performance. La thèse fournit des résultats d'expériences de terrain complexes pratiques en utilisant LoRa, permettant de qualifier l'exactitude de la simulation des couvertures, et les caractéristiques d'ordonnancement des communications. Nous produisons des tables de performance pour les simulations sur les unités de traitement graphique (GPUs) qui montrent que le choix d'une algorithmique parallèle est pertinent sur ces problèmes<br>Long-range radio transmissions open new sensor application fields, in particular for environment monitoring. For example, the LoRa radio protocol enables to connect remote sensors at distance as long as ten kilometers in a line-of-sight. However, the large area covered also brings several difficulties, such as the placement of sensing devices in regard to topology in geography, or the variability of communication latency. Sensing the environment also carries constraints related to the inlerest of sensing points in relation with a physical phenomenon. Thus criteria for designs are evolving a lot from the existing methods, especially in complex terrains. This thesis describes simulation techniques based on geography analysis to compute long-range radio coverages and radio characteristics in these situations. As radio propagation is just a particular case of physical phenomena, it is shown how a unified approach also allows to characterize the behavior of potential physical risks. The case of heavy rainfall and flooding is investigated. Geography analysis is achieved using segmentation tools to produce cellular systems which are in turn translated into code for high-þerformance computations. The thesis provides results from practical complex terrain experiments using LoRa which confirm the accuracy of the simulation, and scheduling characteristics for sample networks. Performance tables are produced for these simulations on current Graphics Processing Units (GPUs)
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Gollbo, Simon, and Adam Sköld. "Base stations for communication in obstructed environments." Thesis, Uppsala universitet, Signaler och System, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-255243.
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The purpose of this project was to produce signal relay stations that could receive information via 2.4 GHz radio and relay the information to a designated target station. If a relay station was located outside of signal range for the target station it was supposed to utilize other relay stations to transfer the information to the target station, so called multi-hop. The would-be application of the relay stations was orienteering. When an orienteer punches a checkpoint the signal stations would relay information of who punched the control, when it was punched and the checkpoint that was punched to the speaker tower in the goal area. The work resulted in prototypes which fulfilled the statement of purpose and was tested at an orienteering competition with satisfactory results. The performance of the prototypes was tested and found adequate for the would-be application.
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Banh, Dennis V. "A ring model for local mobile radio communications with variable packet length." Thesis, Monterey, California: Naval Postgraduate School, 1990. http://hdl.handle.net/10945/27549.
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Approved for public release; distribution unlimited.<br>This thesis presents an analysis of the performance of a local mobile radio communications system utilizing the Aloha random access protocol with variable length packets. The capture phenomenon due to the nearfar effect that enhances the performance of the system is investigated. A tagged packet will capture the base station if its signal-to-interference ratio exceeds a threshold gamma sub zero. Because of the nearfar effect, users near the base station typically have a stronger signal than those farther away. A multiple ring model is used to alleviate this problem. Users in one ring employ different retransmission strategy from those in other rings. A shorter retransmission delay is allocated to users in rings farther from the base station than those closer to the base station in order to achieve approximately the same average delay throughout the network regardless of location.
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Pelteku, Altin E. "Adaptive Suppression of Interfering Signals in Communication Systems." Digital WPI, 2013. https://digitalcommons.wpi.edu/etd-dissertations/138.
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The growth in the number of wireless devices and applications underscores the need for characterizing and mitigating interference induced problems such as distortion and blocking. A typical interference scenario involves the detection of a small amplitude signal of interest (SOI) in the presence of a large amplitude interfering signal; it is desirable to attenuate the interfering signal while preserving the integrity of SOI and an appropriate dynamic range. If the frequency of the interfering signal varies or is unknown, an adaptive notch function must be applied in order to maintain adequate attenuation. This work explores the performance space of a phase cancellation technique used in implementing the desired notch function for communication systems in the 1-3 GHz frequency range. A system level model constructed with MATLAB and related simulation results assist in building the theoretical foundation for setting performance bounds on the implemented solution and deriving hardware specifications for the RF notch subsystem devices. Simulations and measurements are presented for a Low Noise Amplifer (LNA), voltage variable attenuators, bandpass filters and phase shifters. Ultimately, full system tests provide a measure of merit for this work as well as invaluable lessons learned. The emphasis of this project is the on-wafer LNA measurements, dependence of IC system performance on mismatches and overall system performance tests. Where possible, predictions are plotted alongside measured data. The reasonable match between the two validates system and component models and more than compensates for the painstaking modeling efforts. Most importantly, using the signal to interferer ratio (SIR) as a figure of merit, experimental results demonstrate up to 58 dB of SIR improvement. This number represents a remarkable advancement in interference rejection at RF or microwave frequencies.
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Zheng, Rong. "Photonic RF signal processors." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2004. https://ro.ecu.edu.au/theses/812.
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The purpose of this thesis is to explore the emerging possibilities of processing radiofrequency (RF) or microwave signals in optical domain, which will be a key technology to implement next-generation mobile communication systems and future optical networks. Research activities include design and modelling of novel photonic architectures for processing and filtering of RF, microwave and millimeter wave signals of the above mentioned applications. Investigations especially focus on two basic functions and critical requirements in advanced RF systems, namely: • Interference mitigation and high Q tunable filters. • Arbitrary filter transfer function generation. The thesis begins with a review on several state-of-the-art architectures of in-fiber RF signal processing and related key optical technologies. The unique capabilities offered by in-fiber RF signal processors for processing ultra wide-band, high-frequency signals directly in optical domain make them attractive options for applications in optical networks and wide-band microwave signal processing. However, the principal drawbacks which have been demonstrated so far in the in-fiber RF signal processors arc their inflexible or expensive schemes to set tap weights and time delay. Laser coherence effects also limit sampling frequency and introduce additional phase-induced intensity noise.
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Saideh, Michel. "Contributions on radio access techniques for future railway communications system." Thesis, Lille 1, 2019. http://www.theses.fr/2019LIL1I092.
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Avec l’automatisation croissante des fonctions de contrôle commande dans le domaine ferroviaire, on assiste aujourd’hui à une augmentation drastique des échanges d’information. Ces échanges sont cruciaux pour le déploiement du train autonome, la réduction des coûts d'exploitation et de maintenance, l’amélioration de la sécurité. En même temps, de nombreux nouveaux services d’information et de divertissement s’appuyant sur des systèmes de communication sont proposés aux passagers. Pourtant, il n’y a pas aujourd’hui de technologie unique qui puisse satisfaire tous les besoins exigeants en termes de performances. En conséquence, différents projets de recherche industrielle et académique sont en cours aux niveaux européen et international pour développer le système de communication mobile ferroviaire de demain (ou Future Railway Mobile Communication Système – FRMCS). Ce système s’appuiera sur la technologie IP et sera adaptatif, agnostique à la technologie radio et résilient aux évolutions technologiques. En outre, il devra offrir des débits de données élevés, une faible latence, une large bande passante et une utilisation efficace du spectre. Le FRMCS devra être en mesure de choisir en temps réel entre différentes technologies d’accès radio disponibles en fonction des besoins des applications et de l’environnement ferroviaire. Parmi les technologies d’accès disponibles, on peut citer le Wi-Fi, le LTE, les satellites et le standard 5G NR en cours de développement. Ainsi, les contributions de cette thèse de doctorat s’inscrivent dans le cadre du développement d’un système de communication adaptatif (ACS- Adaptable Communication System) pour le ferroviaire en considérant des technologies de pointe du futur standard 5G NR et au-delà. Différentes technologies clef ont récemment été proposées dans le cadre de la standardisation 5G et au-delà. Parmi celles-ci, les techniques d'accès radio jouent un rôle majeur sur les métriques clés, telles que l'utilisation efficace du spectre disponible, les débits de données élevés et la complexité du système émetteur-récepteur. Une des évolutions technologiques majeure dans ce domaine consiste en l’introduction de différentes techniques de modulation multi-porteuses (MCM- Multi-Carrier Modulation) et des techniques d’accès multiple non orthogonales (NOMA- Non-Orthogonal Multiple Access).Dans ce mémoire de thèse de doctorat, nous commençons par étudier les techniques MCM dans le contexte des défis posés par la grande vitesse ferroviaire. Une évaluation des performances est réalisée en considérant différents systèmes multi porteuses dans différents scénarios. La forme d'ondes FBMC (Filtered Bank Multi-Carrier) offre une grande robustesse dans des scénarios de forte mobilité tout en exploitant efficacement le spectre disponible. Cependant, les avantages de la modulation FBMC s'accompagnent d'interférences intrinsèques supplémentaires qui remettent en question les techniques de conception des émetteurs-récepteurs traditionnels. Ainsi, nous proposons différentes contributions qui concernent les techniques d’estimation et d’égalisation du canal pour la forme d’onde FBMC. Les contributions visent à augmenter les performances finales au prix d’une complexité supplémentaire négligeable si on compare à la littérature existante<br>Nowadays, a huge amount of data exchanges is needed in the railway system. This is particularly to support autonomous train, reduce operation and maintenance costs, increase safety and security. In the same time, many new services are offered to passengers. There is no unique technology that can satisfy all these needs. Consequently, different industrial and academical research projects are on-going at European and International levels to develop the Future Railway Mobile Communications System (FRMCS). FRMCS will be IP-based, adaptable, agnostic to radio technology and resilient to technological evolutions. In addition, it should support high data rate, low latency, large bandwidth, and efficient spectrum utilization. The FRMCS is expected to be able to choose in real time between different available radio access technologies in function of applications needs and the surrounding railway environment. Among these technologies, we can mention the Wi-Fi, LTE, satellites and the 5G NR standard in development. Thus, the contributions of this PhD thesis are part of the development of an Adaptable Communication System (ACS) for the railway by considering cutting-edge technologies of the future 5G NR system and beyond. Different key enabling technologies have been proposed recently under the umbrella of 5G and Beyond communication systems. Among which, radio access techniques play major role over key metrics, such as the efficient utilization of the available spectrum, the high data rates, and the computational complexity of the transceiver system. One of the major technological evolution in that domain concerns the introduction of different Multi-Carrier Modulation (MCM) and Non-Orthogonal Multiple Access (NOMA) techniques. In this Ph.D thesis, we start by considering the MCM technology in the context of high speed railway. A performance evaluation study is conducted where different MCM schemes are highlighted in different scenarios. The Filtered Bank Multi-Carrier (FBMC) waveform presents high robustness to high mobility scenarios while exploiting the available spectrum efficiently. However, FBMC advantages come with additional built-in interference that challenges traditional transceiver design techniques. Thereby, we propose different contributions that handle the channel estimation and equalization aspects of the FBMC waveform. The contributions aims to assure better performance at the cost of negligible additional complexity compared with the literature
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Ma, Jian. "The impact of radio signal strength on the design of wireless sensor networks /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?CSED%202007%20MA.
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Sawada, Manabu, Masaaki Katayama, Takaya Yamazato, and Akira Ogawa. "Effect of Nonlinear Amplification on a Spread Spectrum Signal and Receiver Configurations." IEICE, 1994. http://hdl.handle.net/2237/7201.
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Gong, Yi. "Space-time coding for high data-rate wireless communications over space and frequency selective fading channels /." View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202002%20GONG.
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Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2002.<br>Includes bibliographical references (leaves 105-114). Also available in electronic version. Access restricted to campus users.
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Boviz, Dora. "Communications multi-utilisateurs dans les réseaux d’accès radio centralisés : architecture, coordination et optimisation." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLC035/document.
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Dans les réseaux mobiles du future, un déploiement plus dense des points d’accés radio est prévu pour satisfaire la demande accrue de débit, mais les terminaux utilisateurs peuvent être affectés par une interférence inter-cellulaire plus forte. Par chance, la centralisation des traitements de signal en bande de base dans l’achitecture Cloud RAN (C-RAN) offre la possibilité de la coordination et du traitement conjoint de plusieurs cellules. Pour réellement permettre de déployer ces techniques, une étude bout-à-bout du CRAN est nécessaire selon plusieurs aspects, notamment l’architecture fonctionnelle, la stratégie de coordination, l’implémentation du traitement de signal multiutilisateur et les optimisations possibles pour un fonctionnement plus efficace.Dans cette thèse, nous proposons en premier une architecture qui définit le placement des fonctions du traitement en bande de base entre les unités distribuées et le serveur central. Le but de ce design est de permettre la réalisation des fonctions multi-utilisateurs en transmettant avec la moins de débit possible sur les liens de fronthaul reliant les différentes entités. Dans un second temps, nous présentons comment il est possible de coordiner les différentes cellules servies par le C-RAN en utilisant le concept de réseaux définis par logiciels adapté pour les réseaux d’accès radio. Nous avons mis en place un prototype démontrant la faisabilité de la méthode de contrôle proposée. Finalement, nous étudions l’allocation adaptative du débit sur les liens de fronthaul transportant les symboles numériques quantifiés des utilisateurs en besoin de traitement multi-cellulaire sur la voie montante pour exploiter l’interférence entre eux. Nous proposons un modèle d’optimisation qui inclut le coût des transmissions fronthaul pour maximiser ainsi le gain obtenu par l’opérateur du réseau où la communication multiutilisateur a lieu. Nous réalisons l’optimisation pour différents modèles de coût et en utilisants deux types de données: d’abord les estimations de canal supposées parfaites et disponibles en temps réel, puis seulement les statistiques du canal. Nous montrons que la méthode d’optimisation proposée permet d’exploiter plus efficacement les liens de fronthaul dans l’architecture précedemment définie<br>In future mobile networks denser deployment of radio access points is planned to satisfy demand of higher throughput, but an increased number of mobile users can suffer from inter-cell interference. Fortunately, the centralization of base-band processing offered by Cloud Radio Access Network (C-RAN) architecture enables coordination and joint physical layer processing between cells. To make practical deployment of these techniques possible, we have to study C-RAN in an end-to-end view regarding several aspects: the functional architecture of a deployment, the multi-cell coordination strategy, the implementation of multi-user signal processing and possibilities for optimization to increase operational efficiency.In this thesis, first, we propose an architecture defining the placement of base-band processing functions between the distributed remote units and the central processing unit. The aim of this design is to enable multi-cell processing both on the uplink and the downlink while requiring low data rate between the involved entities. Secondly, we study how low latency coordination can be realized inside the central unit using software defined networking adapted to radio access networks. Our demonstration through a real-time prototype deployment shows the feasibility of the proposed control framework. Finally, we investigate adaptive allocation of fronthaul rate that is used for transferring quantized base-band symbols for users participating in uplink multi-cell reception in order to exploit interference between them. We propose an optimization model that includes the cost of fronthaul tranmissions and aims to maximize the gain of network operators from multi-user transmissions in C-RAN. We solve the optimization problem for different fronthaul pricing models, in a scenario where real-time and accurate channel estimates are available and in another where only channel statistics are exploited. Using our method - fitting in the architecture that we have defined - cost efficiency of fronthaul usage can be significantly improved
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Collins, Travis Fredrick. "Implementation and Analysis of Spectral Subtraction and Signal Separation in Deterministic Wide-Band Anti-Jamming Scenarios." Digital WPI, 2013. https://digitalcommons.wpi.edu/etd-theses/297.
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With the increasing volume of wireless traffic that military operations require, the likelihood of transmissions interfering with each other is steadily growing to the point that new techniques need to be employed. Furthermore, to combat remotely operated improvised explosive devices, many ground convoys transmit high-power broadband jamming signals, which block both hostile as well as friendly communications. These wide-band jamming fields pose a serious technical challenge to existing anti-jamming solutions that are currently employed by the Navy and Marine Corps. This thesis examines the feasibility of removing such deterministic jammers from the spectral environment, enabling friendly communications. Anti-jamming solutions in self-jamming environments are rarely considered in the literature, principally due to the non-traditional nature of such jamming techniques. As a result, a combination of approaches are examined which include: Antenna Subset Selection, Spectral Subtraction, and Source Separation. These are combined to reduce environmental interference for reliable transmissions. Specific operational conditions are considered and evaluated, primarily to define the limitations and utility of such a system. A final prototype was constructed using a collection of USRP software defined radios, providing solid conclusions of the overall system performance.
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Gorcin, Ali. "Multidimensional Signal Analysis for Wireless Communications Systems." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4680.
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Wireless communications systems underwent an evolution as the voice oriented applications evolved to data and multimedia based services. Furthermore, current wireless technologies, regulations and the un-
derstanding of the technology are insufficient for the requirements of future wireless systems. Along with the rapid rise at the number of users, increasing demand for more communications capacity to deploy multimedia applications entail effective utilization of communications resources. Therefore, there is a need for effective spectrum allocation, adaptive and complex modulation, error recovery, channel estimation, diversity and code design techniques to allow high data rates while maintaining desired quality of service, and reconfigurable and flexible air interface technologies for better interference and fading management. However, traditional communications system design is based on allocating fixed amounts of resources to the user and does not
consider adaptive spectrum utilization.
Technologies which will lead to adaptive, intelligent, and aware wireless communications systems are expected to come up with consistent methodologies to provide solutions for the capacity, interference, and
reliability problems of the wireless networks. Spectrum sensing feature of cognitive radio systems are a step forward to better recognize the problems and to achieve efficient spectrum allocation. On the other hand, even though spectrum sensing can constitute a solid base to achieve the reconfigurability and awareness goals of next generation networks, a new perspective is required to benefit from the whole dimensions of the available electro hyperspace. Therefore, spectrum sensing should evolve to a more general and comprehensive awareness providing a mechanism, not only as a part of CR systems which provide channel occupancy information but also as a communication environment awareness component of dynamic spectrum access paradigm which
can adapt sensing parameters autonomously to ensure robust identification and parameter estimation for the signals over the monitored spectrum. Such an approach will lead to recognition of communications opportunities in different dimensions of spectrum hyperspace, and provide necessary information about the air interfaces, access techniques and waveforms that are deployed over the monitored spectrum to accomplish adaptive resource management and spectrum access.
We define multidimensional signal analysis as a methodology, which not only provides the information that the spectrum hyperspace dimension in interest is occupied or not, but also reveals the underlaying information regarding to the parameters, such as employed channel access methods, duplexing techniques and other parameters related to the air interfaces of the signals accessing to the monitored channels and more. To achieve multidimensional signal analysis, a comprehensive sensing, classification, and a detection approach is required at the initial stage. In this thesis, we propose the multidimensional signal analysis procedures
under signal identification algorithms in time, frequency. Moreover, an angle of arrival estimation system for wireless signals, and a spectrum usage modeling and prediction method are proposed as multidimensional signal analysis functionalities.
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Tsuda, Hirofumi. "Study on Communication System From the Perspective of Improving Signal-to-Noise Ratio." Kyoto University, 2019. http://hdl.handle.net/2433/242440.
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Tao, Meixia. "Space-time coding schemes for wireless communications over flat fading channels /." View Abstract or Full-Text, 2003. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202003%20TAO.
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Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2003.<br>Includes bibliographical references (leaves 111-118). Also available in electronic version. Access restricted to campus users.
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Cui, Xian. "Efficient radio frequency power amplifiers for wireless communications." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1195652135.
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Saibi, Fadi. "Traitement du signal pour les communications optiques à haute efficacité spectrale." Phd thesis, Télécom ParisTech, 2005. http://pastel.archives-ouvertes.fr/pastel-00001045.
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Les travaux de recherche présentés dans cette thèse s'intéressent à l'application de techniques de modulation et de traitement du signal numérique aux communications optiques. Ils se concentrent sur la conception d'un système de communication optique sur courte distance à 40Gb/s. Pour une longueur d'onde optique donnée, l'accroissement du débit binaire s'obtient généralement en repoussant les limites technologiques afin d'augmenter la vitesse des modulations simples du type "on-off keying". Cette méthode ne satisfait cependant pas les exigences économiques des applications à haut débit sur courte distance. La combinaison du multiplexage de porteuses électriques et d'une modulation à plusieurs niveaux permet de réduire le support fréquentiel et la vitesse de modulation du signal porteur d'information. Des composants typiques des systèmes de transmission à 10Gb/s peuvent ainsi être utilisés pour transmettre 40Gb/s. La technologie de circuits CMOS est également exploitable pour l'intégration économe de fonctions de traitement du signal élaborées. Les structures de traitement du signal adaptatives présentées permettent de réduire les exigences techniques dans la conception des fonctions analogiques. Elles permettent également de compenser les distorsions linéaires dues au canal de transmission et aux variations résultant d'une production industrielle. Des modèles théoriques et numériques validés par l'expérimentation permettent l'analyse du système. Les résultats de simulations numériques montrent qu'un système de communication à 40Gb/s à bas coût et d'une portée dépassant 10km est possible. Nous présentons également un prototype utilisant un circuit intégré test en technologie CMOS réalisant les fonctions de modulation/démodulation pour le canal RF le plus difficile à implémenter, et transmettant des données dans une fibre monomode s'étendant sur plus de 30km.
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Yaacoub, Tina. "Nouvelles approches pour l'estimation du canal ultra-large bande basées sur des techniques d'acquisition compressée appliquées aux signaux à taux d'innovation fini IR-UWB." Thesis, Brest, 2017. http://www.theses.fr/2017BRES0077/document.
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La radio impulsionnelle UWB (IR-UWB) est une technologie de communication relativement récente, qui apporte une solution intéressante au problème de l’encombrement du spectre RF, et qui répond aux exigences de haut débit et localisation précise d’un nombre croissant d’applications, telles que les communications indoor, les réseaux de capteurs personnels et corporels, l’IoT, etc. Ses caractéristiques uniques sont obtenues par la transmission d’impulsions de très courte durée (inférieure à 1 ns), occupant une largeur de bande allant jusqu’à 7,5 GHz, et ayant une densité spectrale de puissance extrêmement faible (inférieure à -43 dBm/MHz). Les meilleures performances d’un système IR-UWB sont obtenues avec des récepteurs cohérents de type Rake, au prix d’une complexité accrue, due notamment à l’étape d’estimation du canal UWB, caractérisé par de nombreux trajets multiples. Cette étape de traitement nécessite l’estimation d’un ensemble de composantes spectrales du signal reçu, sans pouvoir faire appel aux techniques d’échantillonnage usuelles, en raison d’une limite de Nyquist particulièrement élevée (plusieurs GHz).Dans le cadre de cette thèse, nous proposons de nouvelles approches, à faible complexité, pour l’estimation du canal UWB, basées sur la représentation parcimonieuse du signal reçu, la théorie de l’acquisition compressée, et les méthodes de reconstruction des signaux à taux d’innovation fini. La réduction de complexité ainsi obtenue permet de diminuer de manière significative le coût d’implémentation du récepteur IR-UWB et sa consommation. D’abord, deux schémas d’échantillonnage compressé, monovoie (filtre SoS) et multivoie (MCMW) identifiés dans la littérature sont étendus au cas des signaux UWB ayant un spectre de type passe-bande, en tenant compte de leur implémentation réelle dans le circuit. Ces schémas permettent l’acquisition des coefficients spectraux du signal reçu et l’échantillonnage à des fréquences très réduites ne dépendant pas de la bande passante des signaux, mais seulement du nombre des trajets multiples du canal UWB. L’efficacité des approches proposées est démontrée au travers de deux applications : l’estimation du canal UWB pour un récepteur Rake cohérent à faible complexité, et la localisation précise en environnement intérieur dans un contexte d’aide à la dépendance.En outre, afin de réduire la complexité de l’approche multivoie en termes de nombre de voies nécessaires pour l’estimation du canal UWB, nous proposons une architecture à nombre de voies réduit, en augmentant le nombre d’impulsions pilotes émises.Cette même approche permet aussi la réduction de la fréquence d’échantillonnage associée au schéma MCMW. Un autre objectif important de la thèse est constitué par l’optimisation des performances des approches proposées. Ainsi, bien que l’acquisition des coefficients spectraux consécutifs permette une mise en oeuvre simple des schémas multivoie, nous montrons que les coefficients ainsi choisis, ne donnent pas les performances optimales des algorithmes de reconstruction. Ainsi, nous proposons une méthode basée sur la cohérence des matrices de mesure qui permet de trouver l’ensemble optimal des coefficients spectraux, ainsi qu’un ensemble sous-optimal contraint où les positions des coefficients spectraux sont structurées de façon à faciliter la conception du schéma MCMW. Enfin, les approches proposées dans le cadre de cette thèse sont validées expérimentalement à l’aide d’une plateforme expérimentale UWB du laboratoire Lab-STICC CNRS UMR 6285<br>Ultra-wideband impulse radio (IR-UWB) is a relatively new communication technology that provides an interesting solution to the problem of RF spectrum scarcity and meets the high data rate and precise localization requirements of an increasing number of applications, such as indoor communications, personal and body sensor networks, IoT, etc. Its unique characteristics are obtained by transmitting pulses of very short duration (less than 1 ns), occupying a bandwidth up to 7.5 GHz, and having an extremely low power spectral density (less than -43 dBm / MHz). The best performances of an IR-UWB system are obtained with Rake coherent receivers, at the expense of increased complexity, mainly due to the estimation of UWB channel, which is characterized by a large number of multipath components. This processing step requires the estimation of a set of spectral components for the received signal, without being able to adopt usual sampling techniques, because of the extremely high Nyquist limit (several GHz).In this thesis, we propose new low-complexity approaches for the UWB channel estimation, relying on the sparse representation of the received signal, the compressed sampling theory, and the reconstruction of the signals with finite rate of innovation. The complexity reduction thus obtained makes it possible to significantly reduce the IR-UWB receiver cost and consumption. First, two existent compressed sampling schemes, single-channel (SoS) and multi-channel (MCMW), are extended to the case of UWB signals having a bandpass spectrum, by taking into account realistic implementation constraints. These schemes allow the acquisition of the spectral coefficients of the received signal at very low sampling frequencies, which are not related anymore to the signal bandwidth, but only to the number of UWB channel multipath components. The efficiency of the proposed approaches is demonstrated through two applications: UWB channel estimation for low complexity coherent Rake receivers, and precise indoor localization for personal assistance and home care.Furthermore, in order to reduce the complexity of the MCMW approach in terms of the number of channels required for UWB channel estimation, we propose a reduced number of channel architecture by increasing the number of transmitted pilot pulses. The same approach is proven to be also useful for reducing the sampling frequency associated to the MCMW scheme.Another important objective of this thesis is the performance optimization for the proposed approaches. Although the acquisition of consecutive spectral coefficients allows a simple implementation of the MCMW scheme, we demonstrate that it not results in the best performance of the reconstruction algorithms. We then propose to rely on the coherence of the measurement matrix to find the optimal set of spectral coefficients maximizing the signal reconstruction performance, as well as a constrained suboptimal set, where the positions of the spectral coefficients are structured so as to facilitate the design of the MCMW scheme. Finally, the approaches proposed in this thesis are experimentally validated using the UWB equipment of Lab-STICC CNRS UMR 6285
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Cheng, Hui. "New channel estimation and multiuser detection algorithms for multicarrier(MC)-CDMA communications systems." Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B35314321.
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Hamon, Jérémie. "Oscillateurs et architectures asynchrones pour le traitement des signaux radio impulsionnelle UWB." Grenoble INPG, 2009. http://www.theses.fr/2009INPG0077.
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Cette thèse étudie les avantages et les potentiels offerts par le style de conception asynchrone (sans horloge) pour implémenter les traitements numériques de réception des signaux radio impulsionnelle à ultra large bande (UWB), dans le contexte applicatif des réseaux de capteurs. D'une part, des oscillateurs numériques asynchrones ont été étudiés pour réaliser l'implémentation de la base de temps nécessaire aux traitements de réception des signaux radio impulsionnelle, et d'autre part, des algorithmes et des architectures asynchrones de réception de ces signaux radio ont été proposés et validés. Ces différents travaux ont permis de démontrer la pertinence de l’approche asynchrone pour l’implémentation de ce type de traitements, notamment sur le critère de faible consommation. Elles ouvrent ainsi la voie au concept de réseau de capteurs entièrement asynchrones<br>This PhD thesis studies the advantages and opportunities provided by the asynchronous design style to implement the digital part of an UWB Impulse radio receiver, in the context of wireless sensors networks. Ln one hand, asynchronous digital oscillators have been studied to implement the required time base of an impulse radio receiver. On the other hand, asynchronous algorithms and architectures have been proposed and studied. These different studies demonstrate the efficiency and relevance of the asynchronous design approach to implement this kind of processing, especially on the low power criteria. These studies open the way to fully asynchronous wireless sensor networks
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Abdullah, S. N. "Data transmission at 9600 bit/sec over an HF radio link." Thesis, Loughborough University, 1986. https://dspace.lboro.ac.uk/2134/7432.
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The thesis is concerned with serial data transmission at 9600 bit/sec over a voiceband channel, where the main impairments are additive noise and intersymbol interference, and the latter varles slowly with time. The thesis includes a brief description of the ionospheric propagation medium and presents an equivalent baseband model of the HF channel, suitable for computer simulation of quadrature amplitude modulation (QAM) systems. A study of 16-point QAM signals transmitted over voiceband HF channels is then carr-iod out usj-ng the given channel model. Several cost effective near-maximum-likelihood detection processes have been developed for HF modems. Each detector is here preceded by an adaptive linear filter that is adjusted to make the sampled impulse response of the channel and filter minimum phase. These detectors require an accurate knowledge of the sampled impulse response of the channel, if their full potential is to be achieved. The results of computer-simulation tests on the near-maximum-likelihood detectors are given, where these tests assume that other receiver operations such as channel estimation and adaptive linear filtering, together with element timing synchronisation and Doppler shift correction, are carried out perfectly. A recently developed HF channel estimator employing a simple feedforward transversal-filter and requiring knowledge of the number of skywaves is next investigated and a starting up procedure is developed for such an estimator. The technique is then made fully adaptive in the sense that it continues to operate correctly when the number of skywaves changes. Results of computer simulation tests are then presented showing the performance of the above detectors when operating with a channel estimator and adaptive linear filtering. Finally modem synchronisation is studied and various techniques of element timing and carrier frequency synchronisation are proposed.
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Jackson, Kevin. "Blind Front-end Processing of Dynamic Multi-channel Wideband Signals." DigitalCommons@USU, 2016. https://digitalcommons.usu.edu/etd/4692.
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In wireless digital communications, the sender and receiver typically know the modulation scheme with which they will be communicating. Automatic modulation identification is the ability to identify the modulation in a communication system with little to no prior knowledge of the modulation scheme. Many techniques for modulation identification operate on many assumptions including that the input signal is base-banded, the carrier frequency is known and that the signal is narrow-band (i.e. neighboring signals in the wide-band are excluded). This work provides the blind processing of an arbitrary wide-band signal to allow such assumptions. The challenges of such a front-end or pre-processor include detecting signals which can appear at any frequency, with any band-width at any given time and for any arbitrary duration. This work takes as its input a wide-band signal with a random number of sub-signals, each turning on and o at random times and each at random locations in the frequency domain. The output of the system is a collection of signals corresponding to each sub-signal brought down to base-band, isolated in the frequency and time domains, nominally sampled and with estimates of key parameters.
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Cheng, Hui, and 成慧. "New channel estimation and multiuser detection algorithms for multicarrier(MC)-CDMA communications systems." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B35314321.
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HAIDER, KAMRAN. "Peak to Average Ratio Reduction in Wireless OFDM Communication Systems." Thesis, Blekinge Tekniska Högskola, Avdelningen för signalbehandling, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-5309.
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Future mobile communications systems reaching for ever increasing data rates require higher bandwidths than those typical used in today’s cellular systems. By going to higher bandwidth the (for low bandwidth) flat fading radio channel becomes frequency selective and time dispersive. Due to its inherent robustness against time dispersion Orthogonal Frequency Division Multiplex (OFDM) is an attractive candidate for such future mobile communication systems. OFDM partitions the available bandwidth into many subchannels with much lower bandwidth. Such a narrowband subchannel experiences now due to its low bandwidth an almost flat fading leading in addition to above mentioned robustness also to simple implementations. However, one potential drawback with OFDM modulation is the high Peak to Average Ratio (PAR) of the transmitted signal: The signal transmitted by the OFDM system is the superposition of all signals transmitted in the narrowband subchannels. The transmit signal has then due to the central limit theorem a Gaussian distribution leading to high peak values compared to the average power. A system design not taking this into account will have a high clip rate: Each signal sample that is beyond the saturation limit of the power amplifier suffers either clipping to this limit value or other non-linear distortion, both creating additional bit errors in the receiver. One possibility to avoid clipping is to design the system for very high signal peaks. However, this approach leads to very high power consumption (since the power amplifier must have high supply rails) and also complex power amplifiers. The preferred solution is therefore to apply digital signal processing that reduces such high peak values in the transmitted signal thus avoiding clipping. These methods are commonly referred to as PAR reduction. PAR reduction methods can be categorized into transparent methods – here the receiver is not aware of the reduction scheme applied by the transmitter – and non-transparent methods where the receiver needs to know the PAR algorithm applied by the transmitter. This master thesis would focus on transparent PAR reduction algorithms. The performance of PAR reduction method will be analysed both with and without the PSD constrained. The effect of error power on data tones due to clipping will be investigated in this report.
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Smallcomb, Joseph Michael. "Spread spectrum communication over a fading multipath HF channel using transform domain signal processing and a transmitted reference signal." Ohio : Ohio University, 1992. http://www.ohiolink.edu/etd/view.cgi?ohiou1173756311.
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Coskun, Adem. "Downlink Transmission Techniques For Multi User Multi Input Multi Output Wireless Communications." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/2/12608750/index.pdf.
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Multi-user MIMO (MIMO-MU) communication techniques make use of available channel state information at the transmitter to mitigate the inter-user interference. The goal of these techniques is to provide the least interference at the mobile stations by applying a precoding operation. In this thesis a comparison of available techniques in the literature such as Channel Decomposition, SINR Balancing, Joint-MMSE optimization is presented. Novel techniques for the MIMO multi-user downlink communication systems, where a single stream is transmitted to each user are proposed. The proposed methods, different from the other methods in the literature, use a simple receiver to combat the interference. It has been shown that MRC based receivers are as good as more complicated joint MMSE receivers.
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Chen, Qinqin. "Cognitive Gateway to Promote Interoperability, Coverage and Throughput in Heterogeneous Communication Systems." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/30216.
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With the reality that diverse air interfaces and dissimilar access networks coexist, accompanied by the trend that dynamic spectrum access (DSA) is allowed and will be gradually employed, cognition and cooperation form a promising framework to achieve the ideality of seamless ubiquitous connectivity in future communication networks. In this dissertation, the cognitive gateway (CG), conceived as a special cognitive radio (CR) node, is proposed and designed to facilitate universal interoperability among incompatible waveforms. A proof-of-concept prototype is built and tested. Located in places where various communication nodes and diverse access networks coexist, the CG can be easily set up and works like a network server with differentiated service (Diffserv) architecture to provide automatic traffic relaying and link establishment. The author extracts a scalable '“source-CG-destination“ snapshot from the entire network and investigates the key enabling technologies for such a snapshot.
The CG features provide universal interoperability, which is enabled by a generic waveform representation format and the reconfigurable software defined radio platform. According to the trend of an all IP-based solution for future communication systems, the term “waveform“ in this dissertation has been defined as a protocol stack specification suite. The author gives a generic waveform representation format based on the five-layer TCP/IP protocol stack architecture. This format can represent the waveforms used by Ethernet, WiFi, cellular system, P25, cognitive radios etc.
A significant advantage of CG over other interoperability solutions lies in its autonomy, which is supported by appropriate signaling processes and automatic waveform identification. The service process in a CG is usually initiated by the users who send requests via their own waveforms. These requests are transmitted during the signaling procedures. The complete operating procedure of a CG is depicted as a waveform-oriented cognition loop, which is primarily executed by the waveform identifier, scenario analyzer, central controller, and waveform converter together. The author details the service process initialized by a primary user (e.g. legacy public safety radio) and that initialized by a secondary user (e.g. CR), and describes the signaling procedures between CG and clients for the accomplishment of CG discovery, user registration and un-registration, link establishment, communication resumption, service termination, route discovery, etc. From the waveforms conveyed during the signaling procedures, the waveform identifier extracts the parameters that can be used for a CG to identify the source waveform and the destination waveform. These parameters are called “waveform indicators.“ The author analyzes the four types of waveforms of interest and outlines the waveform indicators for different types of communication initiators.
In particular, a multi-layer waveform identifier is designed for a CG to extract the waveform indicators from the signaling messages. For the physical layer signal recognition, a Universal Classification Synchronization (UCS) system has been invented. UCS is conceived as a self-contained system which can detect, classify, synchronize with a received signal and provide all parameters needed for physical layer demodulation without prior information from the transmitter. Currently, it can accommodate the modulations including AM, FM, FSK, MPSK, QAM and OFDM. The design and implementation details of a UCS have been presented. The designed system has been verified by over-the-air (OTA) experiments and its performance has been evaluated by theoretical analysis and software simulation. UCS can be ported to different platforms and can be applied for various scenarios.
An underlying assumption for UCS is that the target signal is transmitted continually. However, it is not the case for a CG since the detection objects of a CG are signaling messages. In order to ensure higher recognition accuracy, signaling efficiency, and lower signaling overhead, the author addresses the key issues for signaling scheme design and their dependence on waveform identification strategy.
In a CG, waveform transformation (WT) is the last step of the link establishment process. The resources required for transformation of waveform pairs, together with the application priority, constitute the major factors that determine the link control and scheduling scheme in a CG. The author sorts different WT into five categories and describes the details of implementing the four typical types of WT (including physical layer analog – analog gateway, up to link layer digital – digital gateway, up-to-network-layer digital gateway, and Voice over IP (VoIP) – an up to transport layer gateway) in a practical CG prototype. The issues that include resource management and link scheduling have also been addressed.
This dissertation presents a CG prototype implemented on the basis of GNU Radio plus multiple USRPs. In particular, the service process of a CG is modeled as a two-stage tandem queue, where the waveform identifier queues at the first stage can be described as M/D/1/1 models and the waveform converter queue at the second stage can be described as G/M/K/K model. Based on these models, the author derives the theoretical block probability and throughput of a CG.
Although the “source-CG-destination” snapshot considers only neighboring nodes which are one-hop away from the CG, it is scalable to form larger networks. CG can work in either ad-hoc or infrastructure mode. Utilizing its capabilities, CG nodes can be placed in different network architectures/topologies to provide auxiliary connectivity. Multi-hop cooperative relaying via CGs will be an interesting research topic deserving further investigation.<br>Ph. D.
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Collins, Travis Fredrick. "Enabling 5G Technologies." Digital WPI, 2017. https://digitalcommons.wpi.edu/etd-dissertations/35.
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The increasing demand for connectivity and broadband wireless access is leading to the fifth generation (5G) of cellular networks. The overall scope of 5G is greater in client width and diversity than in previous generations, requiring substantial changes to network topologies and air interfaces. This divergence from existing network designs is prompting a massive growth in research, with the U.S. government alone investing $400 million in advanced wireless technologies. 5G is projected to enable the connectivity of 20 billion devices by 2020, and dominate such areas as vehicular networking and the Internet of Things. However, many challenges exist to enable large scale deployment and general adoption of the cellular industries. In this dissertation, we propose three new additions to the literature to further the progression 5G development. These additions approach 5G from top down and bottom up perspectives considering interference modeling and physical layer prototyping. Heterogeneous deployments are considered from a purely analytical perspective, modeling co-channel interference between and among both macrocell and femtocell tiers. We further enhance these models with parameterized directional antennas and integrate them into a novel mixed point process study of the network. At the air interface, we examine Software-Defined Radio (SDR) development of physical link level simulations. First, we introduce a new algorithm acceleration framework for MATLAB, enabling real-time and concurrent applications. Extensible beyond SDR alone, this dataflow framework can provide application speedup for stream-based or data dependent processing. Furthermore, using SDRs we develop a localization testbed for dense deployments of 5G smallcells. Providing real-time tracking of targets using foundational direction of arrival estimation techniques, including a new OFDM based correlation implementation.
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Stephens, Richard Brian Leonard. "A study and modelling of the propagation effects of vegetation on radio waves at centimetre-wavelength frequencies." Thesis, University of South Wales, 1998. https://pure.southwales.ac.uk/en/studentthesis/a-study-and-modelling-of-the-propagation-effects-of-vegetation-on-radio-waves-at-centimetrewavelength-frequencies(48d8248f-a287-45e4-96e5-fe8d8e56efae).html.
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With the increase in and more diverse applications of microwave radio communications, the probability of a signal propagating through a medium of vegetation is increased. As a direct result of this demand for microwave communication systems, knowledge is required of the effects of vegetation media on the propagating microwave signal. This enables radio system planners to predict the signal loss more accurately, necessitating a detailed study of the propagation effects of vegetation. A vegetation depth attenuation model has been developed based on the International Telecommunications Union-Radio Sector model and validated against measurements conducted at two microwave frequencies of 11.2 GHz and 20 GHz. The measurements were conducted on a number of sites of differing geometries at different times of the year to obtain the two extreme states of foliage, in- and out-of-leaf. The trees found at the sites were of a number of indigenous species. A variety of species and environments were employed for the outdoor measurements as it was felt that any variation in the signal, occurring as a direct result of the species, climate, environment etc., would be reduced. A further study has been conducted in an anechoic chamber, the purpose being to investigate the depolarising effect of vegetation, to characterise and to ascertain how and to what extent the polarisation of the incident signal is changed as it passes through the vegetation without the effects of climate, location and environment affecting the resultant signal. To enable larger quantities of data to be obtained, collated and subsequently analysed and also to remove any scope for error during the collection of results, two data acquisition programs were written for the two main environments in which the measurements were to be undertaken, that is to say, outdoor and indoor (anechoic chamber) environments. In seeking to provide a model for the prediction of attenuation a radio wave will suffer as it is propagated through a body of vegetation, several models have been examined in turn and their relative merits discussed together with their applicability to the study. After examining the possible models available, the thesis provides a model which enables the prediction of additional attenuation a radiowave signal will suffer as a function of path length (depth) of the vegetation medium and frequency. The model can be recommended for use in the 10-30 GHz band. The study on the depolarisation of signals by vegetation has shown that the components of a vegetation medium e.g. tree trunks, branches and leaves, can cause considerable changes in the polarisation of the incident signal as it propagates through a volume of vegetation. The work presented in this thesis contains new measured results of the polarisation state of the radio wave as it emerges from a vegetation specimen. These results obtained in an anechoic chamber under controlled conditions have demonstrated that additional effects, other than attenuation by absorption and scatter need to be considered in order to characterise and subsequently model the overall effect of vegetation in the radio path of propagating signals.
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Kolevatov, Sergej. "A contribution to bridge the design gap between software and hardware for complex signal processing systems in mobile communications." Aachen Shaker, 2009. http://d-nb.info/1001974972/04.
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Zhou, Junyang. "Enhanced signal propagation models and algorithm selector for providing location estimation services within cellular radio networks." HKBU Institutional Repository, 2007. http://repository.hkbu.edu.hk/etd_ra/776.
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Spencer, Quentin H. "Transmission Strategies for Wireless Multi-user, Multiple-Input, Multiple-Output Communication Channels." Diss., CLICK HERE for online access, 2004. http://contentdm.lib.byu.edu/ETD/image/etd378.pdf.
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Abou, Chakra Sara. "La Boucle Locale Radio et la Démodulation directe de signaux larges bandes à 26GHz." Phd thesis, Télécom ParisTech, 2004. http://pastel.archives-ouvertes.fr/pastel-00001988.
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La Boucle Locale Radio (BLR) ou Wireless Local Loop (WLL) est un système qui connecte les abonnés du réseau téléphonique commuté public (PSTN) grâce à une liaison radio. La BLR doit offrir les services suivants: la voix téléphonique, les données dans la bande du son et les services numériques. En France, les bandes de fréquence allouées à la BLR sont autour de 26 et 3,5 GHz. Les caractéristiques de la BLR à 26 GHz sont définies par la norme IEEE 802.16c. Dans le cadre de cette thèse, une boucle constituée de deux émetteurs/récepteurs fonctionnant dans la bande de 26 GHz a été étudiée. Le système était constitué dans un premier temps de composants disponibles commercialement. Il a été simulé avec le logiciel ADS de Agilent Technologies, et ensuite mis en œuvre au laboratoire RFM. Les récepteurs employés dans cette plate-forme étaient des récepteurs hétérodynes. Leur structure était donc complexe et la transmission altérée par les non-appariements en gain et en phase entre les voies I et Q des démodulateurs en quadrature. Afin de réduire sa complexité tout en gardant les mêmes performances du système, nous avons choisi de proposer une architecture homodyne du récepteur en introduisant le réflectomètre "cinq-port". Le réflectomètre cinq-port est un circuit passif linéaire ayant deux entrées et trois sorties. Il est constitué d'un circuit interféromètrique à cinq accès et de trois détecteurs de puissance. Un démodulateur cinq-port en technologie coaxiale a donc été introduit dans le système de transmission à 26 GHz. La démodulation étant validée avec ce circuit, un démodulateur cinq-port en technologie MHIC était réalisé. Afin de régénérer les signaux I et Q à partir des tensions de sortie du démodulateur cinq-port, un algorithme numérique particulier traite ces trois signaux. Ce traitement effectue simultanément la synchronisation trame et symbole ainsi que la synchronisation porteuse sur chaque trame de donnée transmise. Il inclut aussi une procédure adaptative d'auto-calibrage qui permet de régénérer les signaux I et Q tout en corrigeant tous les défauts de la chaîne de transmission contenant le cinq-port. Ce même traitement permet de corriger les non-appariements entre les deux voies d'un démodulateur classique en quadrature. Le système de transmission complet a été validé en réalisant la démodulation de signaux modulés en QPSK et en 16QAM avec des débits binaires atteignant 40 Mbit/s. Les diagrammes de constellation de phase obtenus étaient bien normalisés et les taux d'erreurs binaires étaient très proches que ceux définis par la norme de la BLR.
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Yang, Xianzhen. "Power Spectrum Prediction of Amplified Dual-Band LTE-Advanced Signals." PDXScholar, 2018. https://pdxscholar.library.pdx.edu/open_access_etds/4351.
Full textAbstract:
In wireless communication, the nonlinearity of a radio frequency (RF) power amplifier is an important issue for power amplifier designers. Since the nonlinearity is generated by the properties of physical components, it is hard to avoid it in producing power amplifiers. Power amplifier designers should know about the nonlinearity in order to compensate for it.
A two-tone test is a relatively widely used method to measure the nonlinearity of a power amplifier, which means the third order intercept point (IP3) can be measured from the two-tone test. Through the two-tone test, researchers have proposed some formulae to present what the amplified Code Division Multiple Access (CDMA) signal is like. They derived formulae in terms of output power, bandwidth, IP3, and IP5 to express the amplified CDMA signal and further to Orthogonal Frequency Division Multiplexing (OFDM) signals. With the development of wireless communication, researchers put their interest increasingly in Multiple Input Multiple Output (MIMO) systems. A formula expressing amplified dual two-tone signals has been proposed. In their research, they discussed what the expressions of intermodulation and cross modulation are and what their locations are.
In this research, dual band LTE-Advanced signals, whose modulation is OFDM are utilized, which means this research proposes a formula expression about the power spectrum of dual-band LTE-Advanced signals. Intermodulation and cross modulation caused by nonlinearity of power amplifiers are then specially discussed. This study will help RF designers to continuously compensate for them.
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Rakotondrainibe, Lahatra. "Conception et réalisation d'un systme de communications sans fil très haut débit à 60 GHz pour les applications WPAN." Rennes, INSA, 2010. http://www.theses.fr/2010ISAR0026.
Full textAbstract:
Les systèmes sans fil à 60 GHz qui sont actuellement en cours de normalisation dans la bande sans licence de 57-66 GHz visent un débit de données de plusieurs Gbit/s pour des applications de futurs réseaux locaux sans fil (WPAN). Jusqu’à présent, de nombreux travaux publiés ont considéré les aspects caractérisation du canal de propagation, applications potentielles, antennes, conception des circuits et des techniques de modulations à 60 GHz. Or, peu d’études portent sur la réalisation d’un système de communications sans fil à 60 GHz et la caractérisation de ses performances dans des environnements réalistes. Ce travail, réalisé dans le cadre du projet Techim@ges, du pôle « Image et Réseaux » et en liaison avec le CPER Palmyre, présente une réalisation expérimentale complète de communications Ethernet Gigabit sans fil à 60 GHz opérant à environ 1 Gbit/s (plus précisément à 875 Mbit/s). Compte tenu du fait que la liaison radio à 60 GHz est mono-pièce, une hybridation de la technologie avec la fibre optique est utilisée pour assurer les communications dans toutes les pièces d’un environnement résidentiel. Le système réalisé dispose d’une bande passante de 2 GHz. En utilisant des blocs millimétriques à 60 GHz existants, le travail a porté principalement sur la conception et la réalisation des modules en bande de base et en FI (codage de canal, modulation, synchronisation, etc. ). Une modulation mono-porteuse DBPSK est retenue à l’émission (Tx). La structure du récepteur proposé est basée sur une démodulation différentielle et sur une unité de traitement du signal composée d’un bloc de synchronisation conjointe trame et octet, d’un débrasseur et d’un décodeur correcteur d’erreurs RS(255,239). Une technique originale de la synchronisation octet/trame est conçue pour obtenir une forte probabilité de détection de préambule et une très faible probabilité de fausse alarme. Le système proposé offre un bon compromis entre performances et complexité. Des mesures de performances ont été réalisées dans différentes configurations et pour différents types d’environnements. Les résultats de mesures ont montré une bonne qualité de transmission et un taux d’erreur binaire (TEB) faible pour une distance entre Tx et Rx de 30 mètres, avec des antennes directives et dans des conditions de visibilité directe<br>60 GHz wireless systems that are currently under standardization within the unlicensed 57-66 GHz band are targeting multi-gigabit data rate for wireless personal area networks (WPANs) applications. Up to now, in the literature, several studies have considered the characterization of the propagation channel, potential applications, antennas, circuit design issues and several modulations at 60 GHz. However, few efforts have been dedicated to the realization of a 60 GHz wireless communications system and the characterization of its performance in realistic environments. This work, conducted under the Techim@ges research project supported by French “Media and Networks Cluster” and in association with Palmyre project, presents a full experimental implementation of a 60 GHz wireless Gigabit Ethernet communication system operating at near gigabit data rate (more precisely at 875 Mbps). As the 60 GHz radio link operates only in a single room configuration, a hybrid technology with the Radio-over-Fiber is used to ensure the communications in all the rooms of a residential environment. The realized system covers 2 GHz available bandwidth. By using the existing 60 GHz millimeter-wave blocks, this work is based on the design and realization of the baseband and intermediate frequency architectures (channel coding, modulation, synchronization, etc. ). A DBPSK single-carrier modulation is retained at the transmitter (Tx). The structure of the proposed receiver (Rx) is based on a simple differential demodulation to reduce the inter-symbol interference effect and a signal processing unit comprising byte/frame synchronization, a descrambler and an RS(255,239) decoder. An original byte/frame synchronization technique is designed to obtain a small value of the preamble false alarm and missing probabilities. The proposed system provides a good trade-off between performance and complexity. Performance measurements have been achieved in different environments and in different configurations. Measurement results show a good communication link quality and a low bit error rate (BER) for a 30 meters distance between Tx and Rx, using high gain antennas and for line-of-sight conditions
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Abou, Chakra Sara. "La boucle locale radio et la démodulation directe de signaux larges bandes à 26 GHz." Paris, ENST, 2004. http://www.theses.fr/2004ENST0045.
Full textAbstract:
La Boucle Locale Radio (BLR) est un système qui connecte les abonnés du réseau téléphonique commuté public avec une liaison radio. En France, les bandes de fréquence allouées à la BLR sont autour de 3,5 et 26 GHz. Une boucle constituée de deux liaisons à 26 GHz a été simulée avec le logiciel ADS et ensuite mise en œuvre au laboratoire RFM à l'ENST. Les récepteurs employés dans ce système utilisaient une architecture superhétérodyne. Afin de réduire la complexité de ces récepteurs, tout en gardant les mêmes performances du système, une architecture homodyne a été proposée en introduisant le réflectomètre cinq-port. Le démodulateur cinq-port est un composant constitué d'un circuit interférométrique à deux entrées RF suivi par trois détecteurs de puissance délivrant trois tensions de sortie. Un circuit permettant la démodulation directe de signaux larges bandes à 26 GHz a ainsi été réalisé en technologie MHIC. La régénération des signaux I&Q à partir des trois tensions de sortie du démodulateur cinq-port nécessite une procédure de calibrage. Par conséquent, une méthode adaptative d'auto-calibrage, intégrant toutes les procédures de synchronisation nécessaires, a été conçue afin de corriger toutes les distorsions du système et de régénérer les signaux en bande de base. La transmission de signaux modulés en QPSK et en 16QAM avec des débits binaires atteignant 40 Mbit/s a validé le fonctionnement du système complet. Les performances obtenues en termes de taux d'erreurs binaires et de sensibilité étaient très proches de celles définies par la norme IEEE 802. 16c de la BLR<br>The Wireless Local Loop (WLL) is a system that uses radio signals to complete the "last mile" between the subscribers and the Public Switched Telephone Network. The frequency bands allocated to the WLL in France are around 3. 5 and 26 GHz. A loop constitued of two transcievers working at 26 GHz was simulated with the ADS software, and then implemented in the RFM laboratory at ENST. This platform receivers were using a superheterodyne architecture. In order to reduce the receiver complexity while keeping the same system performances, a homodyne receiver architecture was proposed by introducing the five-port reflectometer. The five-port demodulator is a component constitued of an interferometric circuit with two RF inputs followed by three power detectors delivering three output voltages. A circuit performing broadband direct demodulation at 26 GHz was then designed in MHIC technology. The regeneration of the I&Q signals from the three output voltages of the five-port demodulator requires a calibration procedure. Thus, an adaptative self-calibration method, including all needed synchronisation procedures, was defined in order to compensate all system distorsions and regenerate the baseband signals. The transmission of modulated signals by QPSK or 16QAM with bit rates reaching 40 Mbit/s validated the complete system. The obtained performance in term of bit error rate or sensitivity were very similar to those defined in the IEEE Standard 802. 16c of the WLL
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Abou, Chakra Sara. "La boucle locale radio et la démodulation directe de signaux larges bandes à 26 GHz /." Paris : École nationale supérieure des télécommunications, 2006. http://catalogue.bnf.fr/ark:/12148/cb409818829.
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