Academic literature on the topic 'Ofdm/oqam'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Ofdm/oqam.'
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.
Journal articles on the topic "Ofdm/oqam"
1
Zhou, Xiao, Chengyou Wang, and Ruiguang Tang. "Channel Estimation Based on IOTA Filter in OFDM/OQPSK and OFDM/OQAM Systems." Applied Sciences 9, no. 7 (April 7, 2019): 1454. http://dx.doi.org/10.3390/app9071454.
Full textAbstract:
In this paper, we present a study of bit error rate (BER) for orthogonal frequency division multiplexing/offset quadrature phase shift keying (OFDM/OQPSK) and OFDM/offset quadrature amplitude modulation (OQAM) systems with an isotropic orthogonal transfer algorithm (IOTA) filter. The novel noise suppression method based on an IOTA filter is proposed to reduce the error of channel estimation caused by additive white Gaussian noise (AWGN). The OFDM/OQPSK and OFDM/OQAM systems do not insert the guard interval (GI) and pilots in the signal frames, thus they possess transmission efficiency. An analysis was carried out for convolutional coded OFDM/OQPSK and OFDM/OQAM systems in Rayleigh fading channels with generator polynomials and constraint lengths. Compared with conventional OFDM/QPSK and OFDM/QAM systems with the insertion of comb-type pilots, the proposed IOTA filter-based channel estimation method can provide significant energy per bit to time-varying noise power spectral density ratio gains over time and frequency-selective propagation Rayleigh fading channels in OFDM/OQPSK and OFDM/OQAM systems.
2
Qiu, Shangfei, Lunsheng Xue, and Peng Wu. "Improved Interference Cancelation Channel Estimation Method in OFDM/OQAM System." Mathematical Problems in Engineering 2018 (November 1, 2018): 1–9. http://dx.doi.org/10.1155/2018/7076967.
Full textAbstract:
To the significant amount of pilot overhead of the interference cancelation methods in orthogonal frequency division multiplexing (OFDM) based on offset quadrature amplitude modulation (OFDM/OQAM) system, we proposed an improved interference cancelation method (ICM) for OFDM/OQAM system in this paper. In this method, we use the auxiliary pilot (AP) to eliminate the influence of the intersymbol interference on channel estimation, which can reduce the pilot overhead of OFDM/OQAM system significantly. At the same time, to improve the channel estimation performance, we analyze the source of the intrinsic interference of system and its distribution in time and frequency domain, then, we reset the interference cancelation range of AP, which can cancel more intrinsic interference for OFDM/OQAM system. According to the results of performance analysis, compared to the conventional interference cancelation methods, the proposed method performs better in terms of energy efficiency and spectral efficiency. Also, the simulation results of the proposed method show that the proposed method can outperform traditional interference cancelation methods in channel estimation performance.
3
Zorba, Nizar, and Faouzi Bader. "Spatial Diversity Scheme to Efficiently Cancel ISI and ICI in OFDM-OQAM Systems." Journal of Computer Systems, Networks, and Communications 2010 (2010): 1–10. http://dx.doi.org/10.1155/2010/576243.
Full textAbstract:
This paper is based on an Offset Quadrature Amplitude Modulation (OQAM) Orthogonal Frequency Division Multiplexing (OFDM) transmission scheme that is operated without a Cyclic Prefix (CP), where the multiple transmitting antennas are employed to substantially reduce the inherent intersymbol and intercarrier interference. The proposed scheme avoids the use of the CDMA technology to get rid of the interference. The nonemployment of the CP increases the spectral efficiency in comparison with classical CP-OFDM systems, as it does not employ the CP for its correct performance. On the other hand, the non-employment of the CP comes at cost of Intersymbol Interference (ISI). This paper presents a method which cancels the interference terms by employing a multiantenna precoding strategy based on spatial diversity OQAM-OFDM scheme, so that the overall system can get the advantage of the CP removal while no ISI is generated. Moreover, the proposed system benefits from the multiuser gain through an opportunistic scheduler at the transmitter side to select the user with the best channel characteristics at each instant. The resultant scheme OQAM-OFDM-MIMO data rate is obtained in a closed form expression and proved to be higher than the classical CP-OFDM systems.
4
Lin, Hao, and Pierre Siohan. "Robust channel estimation for OFDM/OQAM." IEEE Communications Letters 13, no. 10 (October 2009): 724–26. http://dx.doi.org/10.1109/lcomm.2009.091325.
Full text
5
Çalişir, Bircan, and Ayhan Akbal. "Hardware Prototyping and Modelling of Prototype Filter for FBMC." Wireless Communications and Mobile Computing 2020 (November 16, 2020): 1–10. http://dx.doi.org/10.1155/2020/8831568.
Full textAbstract:
Filter bank multicarrier (FBMC) is one of the effective candidates for the fifth generation of wireless communication networks. 5G (5th-generation wireless systems) is accepted as the next major stage of mobile telecommunication technology. The extent of 5G will be expanded mobile broadband services to next-generation automobiles and connected machines. In particular, filter bank multicarrier with offset quadrature amplitude modulation (FBMC/OQAM) is determined as the future generation 5G air interface by researchers recently. Filter bank multicarrier (FBMC) is admitted as one of the alternative technologies for multicarrier modulation. Compared to orthogonal frequency-division multiplexing (OFDM), FBMC has better spectrum shape and supports mobility. Therefore, efficient hardware implementations have highly interested researchers. Cyclic prefix (CP) and guard band are used for orthogonal frequency-division multiplexing (OFDM) and this causes loss of spectral efficiency, but FBMC applications do not need CP and guard band. Due to the fact that FBMC has offset QAM (OQAM) and band-limited filtering features on each subcarrier, the need for CP and guard band is eliminated. In this paper, novel pipelined hardware architecture of the filter design of FBMC/OQAM modulator has been proposed.
6
Shi, Qiao, Xueting Li, Tianxian Zhang, Xinyu Liu, and Lingjiang Kong. "IRCI-free OQAM-OFDM radar pulse compression." Signal Processing 180 (March 2021): 107869. http://dx.doi.org/10.1016/j.sigpro.2020.107869.
Full text
7
Hou, Weikun, and Benoit Champagne. "Semiblind Channel Estimation for OFDM/OQAM Systems." IEEE Signal Processing Letters 22, no. 4 (April 2015): 400–403. http://dx.doi.org/10.1109/lsp.2014.2361663.
Full text
8
Mattera, Davide, and Mario Tanda. "Data-aided synchronization for OFDM/OQAM systems." Signal Processing 92, no. 9 (September 2012): 2284–92. http://dx.doi.org/10.1016/j.sigpro.2012.02.022.
Full text
9
Kong, Dejin, Xiang-Gen Xia, Tao Jiang, and Xiqi Gao. "Channel Estimation in CP-OQAM-OFDM Systems." IEEE Transactions on Signal Processing 62, no. 21 (November 2014): 5775–86. http://dx.doi.org/10.1109/tsp.2014.2356441.
Full text
10
Savaux, Vincent, Faouzi Bader, and Jacques Palicot. "OFDM/OQAM Blind Equalization Using CNA Approach." IEEE Transactions on Signal Processing 64, no. 9 (May 2016): 2324–33. http://dx.doi.org/10.1109/tsp.2016.2519000.
Full textDissertations / Theses on the topic "Ofdm/oqam"
1
Skrzypczak, Alexandre. "Contribution à l'étude des modulations multiporteuses OFDM / OQAM et OFDM suréchantillonnées." Rennes 1, 2007. http://www.theses.fr/2007REN1S136.
Full textAbstract:
Actuellement, pour la transmission dans des canaux multi-trajets, le choix de la modulation se base surtout sur des schémas de transmission multiporteuse du fait de leur robustesse vis-à-vis de la sélectivité fréquentielle. Parmi ces solutions, la modulation OFDM est la modulation de référence. Mais cette modulation, basée sur une mise en forme spectrale rectangulaire, possède des inconvénients notables comme une densité spectrale de puissance ayant des lobes secondaires très élevés. D'autres modulations ont alors été développées pour lutter contre ce problème, parmi lesquelles l'OFDM/OQAM et l'OFDM suréchantillonné, ceci au prix de nouvelles contraintes. L'objectif de cette thèse est d'étudier ces modulations avec forme d'onde sur plusieurs aspects critiques des transmissions. Nous nous focalisons ainsi sur l'étude de la densité spectrale de puissance, du PAPR et de sa réduction, et de l'estimation de canal. Une application au courant porteur en ligne est enfin réaliséeNowadays, for the transmission over multipath fading channel, the choice of multicarrier solutions becomes more and more frequent because of their remarkable robustness with respect to frequency selective distortions. The OFDM solution then stands for a reference modulation. However, this modulation, based on a rectangular pulse shape, exhibits some noticeable drawbacks, like a power spectral density with high sidelobes. In order to cope with this problem, new solutions have been developed using non-rectangular pulse shapes. Nevertheless, modulations like OFDM/OQAM and oversampled OFDM lead to specific constraints. This Ph. D. Thesis aims at studying these pulse-shaped multicarrier modulations on several critical aspects of transmission. We focus on the study of the power spectral density, the PAPR and its reduction, and the channel estimation problem. We finally apply these solutions to power line communications
2
Gharba, Mohamed. "Study and evaluation of a frequential multiplexing based on OFDM/OQAM." Phd thesis, Conservatoire national des arts et metiers - CNAM, 2012. http://tel.archives-ouvertes.fr/tel-00767401.
Full textAbstract:
This thesis is dedicated to the study of the OFDM/OQAM modulation as an alternative to the OFDM modulation. We treat more especially the multi-user environment. In this respect, synchronization aspects are crucial. The different options plus the choice of the waveform are examined in this point of view. Another objective is to precisely show how the OFDM/OQAM can be adapted to a cellular transmission type, taking as reference the 3GPP/LTE system. The main contributions we have made are : 1) Analysis of the desynchronization phenomena : we analyze the effect of desynchronization, according to the time and frequency axes, on the performance of OFDM/OQAM at the receiver side. 2) Synchronization method : we analyze a method of temporal synchronization defined in a single user OFDM/OQAM transmission and we adapt it to a multi-user scenario type. 3) Proposing for a multiple access scheme : we propose a multiple access scheme based on theOFDM/OQAM modulation, alternative to the known techniques OFDMA and SC-FDMA, for the UL transmission in a 3GPP/LTE context.
3
Bazin, Alexis. "Massive MIMO for 5G Scenarios with OFDM and FBMC/OQAM Waveforms." Thesis, Rennes, INSA, 2018. http://www.theses.fr/2018ISAR0019/document.
Full textAbstract:
Avec l'augmentation du trafic de données, la multiplication des objets connectés et la diversification des types de communication, la cinquième génération de réseaux cellulaires (5G) doit relever un grand nombre de défis. Dans ce contexte, les systèmes« massive MIMO » présentent de nombreux avantages en utilisant un grand nombre d'antennes combiné à des techniques de traitement de signal adaptées. De plus, l'utilisation de la modulation FBMC/OQAM au lieu de la modulation OFDM pourrait améliorer la performance des systèmes dans ce11aines situations. En premier lieu, cette thèse se centre sur des scénarios véhiculaires. En par1iculier, les systèmes« massive MIMO » sont proposés dans le but de combattre les interférences dues à l'effet Doppler pour la voie montante. Nous montrons ainsi de manière analytique que l'augmentation du nombre d'antennes implique une réduction drastique de l'impact de l'effet Doppler. De plus, les performances des modulations OFDM et FBMC/OQAM sont comparées dans ce contexte pour des environnements« Non-Line-Of-Sight » (NLOS) et« Line-Of-Sight » (LOS). Le second scéna1io étudié dans cette thèse considère les communications dans des zones mal desservies. Dans ce contexte, les systèmes« massive MIMO » permettent de créer un lien sans-fil longue-po11ée de type« backhaul » entre deux stations de base. Ainsi, le coût de déploiement des réseaux r cellulaires est réduit. Dans cette thèse, un nouveau précodeur « massive MIMO » est proposé dans le but d'utiliser la même bande de fréquence pour le liens accès et« backhaul ». De plus, l'impact d'une désynchronisation entre les liens d'accès et le lien « backhaul » est étudié et l'utilisation de la modulation FBMC/OQAM pour le lien« backhaul » est examinéeESUME DE LA THESE EN ANGLAIS With the increase of the global data tmffic, the multiplication of co1mected devices and the diversification of the communication types, the fifth generation of cellular networks (5G) has to overcome a se1ies of challenges. In this context, massive MlMO systems hold a wide range of benefits by using a large number of antennas combined with appropriate signal processing techniques. Additionally, the use of the FBMC/OQAM modulation instead of the classical OFDM modulation may enhance the performance of the systems in cer1ain situations. Firstly, this thesis focuses on vehicular scenarios. In par1icular, massive MIMO systems are proposed to overcome the interference due to the Doppler effect for the uplink. We thus analytically highlight that increasing the number of receive antermas induces a drastic reduction of the impact of the Doppler effect. Moreover, the perfonnance of the OFDM and the FBMC/OQAM modulations are compared in this context for Non-Line-Of-Sight (NLOS) and Line-Of-Sight (LOS) environments. The second scenario investigated in this thesis considers communications in wide underse1ved areas. In this context, massive MIMO systems allow to create a long-range wireless back.haul link between two base stations. Thereby, the cost of deployment of the cellular networks is reduced. In this thesis r a new massive MLMO precoding technique is proposed in order to use the same fequency band for the backhaul link and the access links. Moreover, the impact of a desynchronization between the back haul link and the access links is studied and the use of the FBMC/OQAM modulation for the backhaul link is discussed
4
Nadal, Jérémy. "Filtered multicarrier waveforms in the context of 5G : novel algorithms and architecture optimizations." Thesis, Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2017. http://www.theses.fr/2017IMTA0065/document.
Full textAbstract:
La 5ème génération de réseaux mobiles (5G), actuellement en cours de standardisation, prévoit de nouveaux scénarios de communication dans l’évolution vers un monde entièrement connecté et communicant. Dans ce contexte, un nombre très important de techniques avancées sont en cours d’exploration pour répondre aux nombreux défis imposés en termes de débit, de latence, de consommation énergétique, et de capacité à faire communiquer entre eux, efficacement, des milliards d'objets très différents. Parmi les techniques les plus prometteuses de la couche physique, de nouvelles formes d'ondes multiporteuses filtrées sont proposées. Bien qu’elles offrent un meilleur confinement spectral et une meilleure localisation en temps et en fréquence par rapport à l’OFDM de la 4G, elles présentent des limitations soit en termes de complexité soit en termes de performance et d’intégration. De plus, ces formes d’ondes sont évaluées d’un point de vue théorique et les résultats ne sont pas toujours validés sur des plateformes matérielles de preuve de concept reproduisant les conditions réelles des scénarios de la 5G.Dans ce contexte, les travaux de cette thèse proposent plusieurs contributions originales aussi bien au niveau algorithmes de traitement qu’au niveau architectures matérielles. Dans le domaine algorithmique,les travaux réalisés ont mené aux contributions suivantes : (1) Un nouveau filtre prototype court est proposé pour la forme d’onde FBMC/OQAM. Des analyses analytiques, complétées par simulation,montrent que le filtre proposé permet d’améliorer la résistance aux erreurs de synchronisation temporel et de réduire la complexité du récepteur FBMC de type « frequency-spread » comparé aux autres filtres de la littérature, (2) Un nouveau type de récepteur FBMC adapté pour les filtres courts est proposé. Ce récepteur a la particularité d’améliorer sensiblement la résistance aux canaux doublement dispersifs pour des filtres courts, et de supporter les communications asynchrones, (3) Un émetteur UF-OFDM original de complexité significativement réduite par rapport à la littérature est proposé. Contrairement aux techniques existantes, l’émetteur proposé n’introduit aucune approximation dans le signal généré, et préserve ainsi le confinement spectral de la forme d’onde. Dans le domaine de la conception matérielle, les travaux réalisés durant cette thèse ont mené aux contributions suivantes : (4) Une architecture matérielle optimisée des émetteurs FBMC et UF-OFDM de complexité comparable à OFDM, (5) Une architecture matérielle optimisée de l’étage de filtrage du récepteur FBMC « frequency-spread », avec une complexité comparable à celle d’un récepteur « polyphase-network », et (6) Une des premières plateformes matérielles de preuve de concept de la 5G, pouvant évaluer les performances des formes d’ondes pour les différents services de la 5GThe 5th generation of mobile communications is fore seen to cope with a high degree of heterogeneity in terms of services: enhanced mobile broadband, massive machine, vehicular and mission critical communications, broadcast services. Consequently, diverse and often contradicting key performance indicators need to be supported, such as high capacity/user-rates, low latency, high mobility, massive number of devices, low cost and low power consumption. 4G is not designed to efficiently meet such a high degree of heterogeneity: the OFDM waveform exhibits several limitations in terms of spectrum usage and robustness to frequency and timing synchronization errors. In order to overcome these limitations and to cope with the new 5G requirements,several research initiatives have been conducted to design new waveforms. Proposed candidates, such as FBMC/OQAM or UF-OFDM,are mainly based on multicarrier modulation with specific filtering scheme used on the top of the OFDM basis. However, most of the proposed new waveforms are often studied and analyzed at the algorithmic level considering mainly the quality of the communication link. Therefore, the investigation of low-complexity implementations and the availability of real hardware prototypes are of high interest for performance validation and proof-of-concept of the diverse proposed communication techniques. In the above context, this thesis work proposes several original contributions in the algorithm and the hardware design domains. In the algorithm domain, this work leads to the following contributions: (1) Anovel short prototype filter for FBMC allowing for near perfectreconstruction and having the same size as one OFDM symbol is proposed. Using the Frequency Spread implementation for the FBMC receiver, analytical studies and simulation results show that the proposed filter exhibits better robustness to several types of channel impairments when compared to state-of-the-art short prototype filters and OFDM modulation. (2) A novel FBMC receiver technique suitable for short filters is proposed. This receiver enables to greatly improve the robustness against double dispersive channels for short filters, and enables the support of asynchronous communications, (3) A novel low complexityUF-OFDM transmitter without any signal quality loss isproposed. For small subband sizes, the complexity becomescomparable to OFDM regardless of the number of allocated subbands.In the hardware design domain, this thesis work leads to the following contributions: (4) An efficient pipelined hardware architecture of the FBMC/OQAM transmitter capable of supporting several filter lengths and targeting low complexity is proposed and compared to typical FBMC/OQAM and OFDM implementations, (5) An optimized frequency spread based hardware architecture of the filtering stage is proposed for the designed short prototype filter, showing lower complexity than the classical Poly Phase-Network-based implementation, (6) One of the first flexible and efficient hardware platforms for 5G waveform design, allowing the support of several communication scenarios as foreseen in 5G
5
Selvakumar, Vinodhkumar, Samuel Nemalladinne, and Premkumar Arumugam. "Analysis of LTE Radio Frame by eliminating Cyclic Prefix in OFDM and comparison of QAM and Offset-QAM." Thesis, Linnéuniversitetet, Institutionen för datavetenskap, fysik och matematik, DFM, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-21602.
Full textAbstract:
Spectral efficiency is the key factor for the development of future wireless communications. Orthogonal Frequency Division Multiple Access (OFDMA) is the multiple access technology used at physical layer of latest wireless communication technologies. Anything on the improvement or overcoming the disadvantage of the present system will be considered for the future wireless systems. Long Term Evolution (LTE) is one of the 4th generation wireless communications and it is taken as the reference system in this thesis. The main concern of this thesis is to analyze the LTE radio frame. We designed and simulated the OFDM system with cyclic prefix, its Bit Error Rate (BER) is verified by changing the Signal to Noise Ratio (SNR) value and we investigated the OFDM system by eliminating the cyclic prefix. By eliminating cyclic prefix bandwidth efficiency is achieved, though using cyclic prefix in OFDM has more advantages. Filter banks are used to compensate the advantages of cyclic prefix when it is removed. Introducing Offset in QAM results in less distortion and amplitude fluctuations. We designed, simulated and compared the QAM digital modulation with Offset-QAM digital modulation its BER vs. SNR are verified using simulations on MATLAB.
6
Lele, Chrislin. "Ofdm/oqam : méthodes d'estimation de canal, et combinaison avec l'accès multiple CDMA ou les systèmes multi-antennes." Paris, CNAM, 2008. http://www.theses.fr/2008CNAM0635.
Full textAbstract:
Les recherches en communications numériques ont dans leur objectif d'augmenter le débit des systèmes de transmission avec des réalisations à faible complexité d'implémentation. En présence de canaux multi-trajets, les systèmes multiporteuses, notamment le CP-OFDM, sont de plus en plus utilisés car ils offrent un excellent compromis entre débits élevés et faible complexité d'implementation. De plus, comparées aux systèmes monoporteuses, les technologies multiporteuses permettent une meilleure exploitation de la diversité fréquentielle du canal de communication. Les standards ADSL, IEEE802. 11a. . . Reposent déjà sur la technologie CP-OFDM et les nouveaux standards, comme IEEE802. 11n, combinent le CP-OFDM avec les technologies MIMO pour améliorer les débits de transmission et exploiter efficacement la diversité spatiale du canal. Par ailleurs, dans la plupart des systèmes, le canal de communication doit être partagé entre plusieurs utilisateurs, d'où la nécessité de recourir aux techniques d'accès. Le CDMA est l'une des techniques d'accès les plus prometteuses et sa combinaison avec le CP-OFDM a donné lieu au MC-CDMA. Cependant, le CP-OFDM a deux inconvénients majeurs. Premièrement, l'utilisation du CP correspond à une perte d'information utile car la function CP est de l'information redondante. Et, deuxièmement, le filtre de transmission utilisé en CP-OFDM est la fonction porte autrement dit une fonction mal localisée en fréquence. L'implication directe de cette mauvaise localisation est la difficulté de faire respecter par le CP-OFDM des spécifications de masque d'émission contraignantes. En particulier, pour éviter les interférences avec les systèmes voisins en fréquence, les fréquences nulles sont en général insérées aux bords du spectre d'émission d'où une perte d'informations utiles. Pour remédier à ces inconvénients, l'OFDM/OQAM semble être une bonne alternative. En effet, la modulation OFDM/OQAM n'utilise pas de CP et elle offre la possibilité d'utiliser différents types de filtre prototype. L'OFDM/OQAM repose pour cela sur une orthogonalité réelle contrairement au CP-OFDM qui utilise une orthogonalité complexe. Le but de cette thèse est dans une première partie de montrer qu'il est possible dans certaines conditions, de réaliser une égalisation à un coefficient en OFDM/OQAM comme en CP-OFDM. Nous présentons dans ce cadre des méthodes d'estimation de canaux en OFDM/OQAM suivant les modes préambule et pilotes répartis. Les performances de ces méthodes d'estimation sont comparées à celles utilisées pour les systèmes CP-OFDM. Dans la suite de la thèse, nous analysons la combinaison OFDM/OQAM et CDMA, avec notamment la possibilité d'obtenir une orthogonalité complexe en OFDM/OQAM grâce aux codes de Walsh-Hadamard. Une comparaison avec le système MC-CDMA est effectuée. Un dernier axe d'étude concerne les systèmes multi-antennes. Nous analysons notamment les gains de diversité spatiale et l'augmentation des débits de transmission. Ensuite nous nous intéressons à la combinaison OFDM/OQAM et MIMO. Nous examinons la possibilité ou non d'appliquer à l'OFDM/OQAM les schémas de multiplexage spatial et ceux de type AlamoutiOne important goal in digital communication research is to increase the transmission bit rate while keeping a low complexity structure for the transmitter and receiver. Nowadays, in the presence of multi-path channels, multi-carrier modulations such as CP-OFDM are more and more used since they provide a good trade-off between higher bit rate and complexity. Moreover, compared to single-carrier systems, multi-carrier systems permit a better use of the channel frequency diversity. Systems or standards such as ADSL or IEEE802. 11a have already implemented the CP-OFDM modulation. New standards like IEEE802. 11n combine CP-OFDM and MIMO in order to increase the bit rate and to provide a better use of the channel spatial diversity. As the communication medium has to be shared between multiple users, access techniques are needed. One of the most promising access technique is CDMA and its combination with CP-OFDM has led to the so-called MC-CDMA. However, the CP leads to a loss of spectral efficiency as it contains redundant information. Moreover, the prototype filter used in CP-OFDM is the rectangular window one, thus it has poor frequency localization. This poor frequency localization makes it difficult for CP-OFDM systems to respect stringent specifications of spectrum masks. This is why null sub-carriers are inserted at the frequency boundaries of CP-OFDM systems in order to avoid interferences with close systems in frequency. Adding null sub-carriers also means loosing spectral efficiency. To overcome these difficulties, OFDM/OQAM seems to be a good alternative. Firstly, because OFDM/OQAM does not use any CP and, secondly, because it offers the possibility to use different prototype filters. Indeed, for a given type of time-frequency transmission lattice, the orthogonality constraint for OFDM/OQAM is relaxed being limited to the real field while for OFDM it has to be satisfied in the complex field. Thus, there is more degree of freedom for OFDM/OQAM prototype filters. The aim of this thesis is, in the first part, to show that it is possible with OFDM/OQAM to perform a one tap channel equalization per subcarrier as in CP-OFDM. For realistic transmission channels, this one tap equalization is only valid within some channel hypotheses regarding the maximum delay spread and the Doppler effect. Then, it must be preceded by a channel estimation step. Therefore, a set of channel estimation methods is proposed for the preamble and scattered modes. In the second part, we analyze the combination between OFDM/OQAM and CDMA and we show that it is possible to have a complex orthogonality in OFDM/OQAM thanks to the Walsh-Hadamard codes. A comparison with MC-CDMA is also carried out. Finally, we study multi-antennas system. We analyze the spatial diversity gain and the data rate increase. The combination between OFDM/OQAM and MIMO is also studied for the spatial multiplexing and Alamouti schemes
7
Du, Jinfeng. "Pulse Shape Adaptation and Channel Estimation in Generalised Frequency Division Multiplexing Systems." Licentiate thesis, Stockholm : Informations- och kommunikationsteknik, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9457.
Full text
8
Gaeddert, Joseph Daniel. "Facilitating Wireless Communications through Intelligent Resource Management on Software-Defined Radios in Dynamic Spectrum Environments." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/77061.
Full textAbstract:
This dissertation provides theory and analysis on the impact resource management has on software-defined radio platforms by investigating the inherent trade-off between spectrum and processing effciencies with their relation to both the power consumed by the host processor and the complexity of the algorithm which it can support. The analysis demonstrates that considerable resource savings can be gained without compromising the resulting quality of service to the user, concentrating specifically on physical-layer signal processing elements commonly found in software definitions of single- and multi-carrier communications signals.
Novel synchronization techniques and estimators for unknown physical layer reference parameters are introduced which complement the energy-quality scalability of software-defined receivers. A new framing structure is proposed for single-carrier systems which enables fast synchronization of short packet bursts, applicable for use in dynamic spectrum access. The frame is embedded with information describing its own structure, permitting the receiver to automatically modify its software configuration, promoting full waveformfl‚exibility for adapting to quickly changing wireless channels. The synchronizer's acquisition time is reduced by exploiting cyclostationary properties in the preamble of transmitted framing structure, and the results are validated over the air in a wireless multi-path laboratory environment. Multi-carrier analysis is concentrated on synchronizing orthogonal frequency-division multiplexing (OFDM) using offset quadrature amplitude modulation (OFDM/OQAM) which is shown to have significant spectral compactness advantages over traditional OFDM. Demodulation of OFDM/OQAM is accomplished using computationally effcient polyphase analysis filterbanks, enabled by a novel approximate square-root Nyquist filter design based on the near-optimum Kaiser-Bessel window. Furthermore, recovery of sample timing and carrier frequency offsets are shown to be possible entirely in the frequency domain, enabling demodulation in the presence of strong interference signals while promoting heterogeneous signal coexistence in dynamic spectrum environments.
Resource management is accomplished through the introduction of a self-monitoring framework which permits system-level feedback to the radio at run time. The architecture permits the radio to monitor its own processor usage, demonstrating considerable savings in computation bandwidths on the tested platform. Resource management is assisted by supervised intelligent heuristic-based learning algorithms which use software-level feedback of the radio's active resource consumption to optimize energy and processing effciencies in dynamic spectrum environments. In particular, a case database-enabled cognitive engine is proposed which abstracts from the radio application by using specific knowledge of previous experience rather than relying on general knowledge within a specific problem domain.Ph. D.
9
Lahbabi, Naila. "Faster than Nyquist transceiver design : algorithms for a global transmission-reception enhancement." Thesis, Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2017. http://www.theses.fr/2017IMTA0017/document.
Full textAbstract:
La croissance exponentielle du trafic de données sans fils, causée par l'Internet mobile et les smartphones, contraint les futurs systèmes radio à inclure des modulations/formes d'ondes plus avancées offrant un débit plus élevé et une utilisation efficace des ressources spectrales. Les transmissions dites Faster-Than-Nyquist (FTN), introduites en 1975, sont parmi les meilleurs candidates pour répondre à ces besoins. En transmettant les symboles à une cadence plus rapide que celle définie par le critère de Nyquist, FTN peut théoriquement augmenter le débit mais en introduisant des interférences en contrepartie. Dans cette thèse, nous explorons le concept des transmissions FTN à travers un canal AWGN (Additive White Gaussian Noise) dans le contexte des modulations OFDM/OQAM (Orthogonal Frequency Division Multiplexing with Offset Quadrature Amplitude Modulation).L'objectif principal de cette thèse est de présenter un système OFDM/OQAM qui permet de transmettre l'information au-delà de la cadence de Nyquist tout en tenant en compte la complexité globale du système. Tout d'abord, nous proposons une nouvelle implémentation efficace des systèmes OFDM/OQAM appliquant le concept FTN, désignée ici par FTN-OQAM, qui garde la même complexité que les systèmes OFDM/OQAM et qui permet un gain en débit très proche du gain théorique. Vu que la condition de Nyquist n'est plus respectée, le signal transmis est maintenant perturbé par des interférences. Pour remédier à ce problème, nous proposons un récepteur basé sur le principe de l'égalisation linéaire sous le critère minimum erreur quadratique moyenne avec annulation d'interférences appelé MMSE LE-IC. Le but de notre système est d'augmenter le débit de transmission, ce qui signifie que des constellations d'ordres élevés seront ciblées. Dans ce contexte, le MMSE LE-IC, dont la complexité est indépendante de la constellation, représente un bon compromis entre efficacité et complexité. Puisque la modulation OFDM/OQAM utilise différents types de formes d'ondes, nous proposons pour plusieurs d'entre elles un algorithme pour déterminer la valeur minimale du facteur d'accélération, en fonction de l'ordre de constellation, qui apporte un gain en efficacité spectrale tout en gardant les mêmes performances que les systèmes respectant le critère de Nyquist à un SNR fixé. Ensuite, nous étudions l'amélioration du traitement itératif de l'émetteur-récepteur. La méthode proposée consiste à combiner un précodeur avec le système FTN-OQAM afin de réduire les interférences causées par du FTN à l'émission. Nous proposons un modèle de précodage dispersé, car il est difficile de précoder conjointement tous les symboles transmis. Nous présentons trois familles de précodeurs avec les récepteurs correspondants. En outre, nous modifions différents blocs de l'émetteur FTN-OQAM tels que le codage canal, le mappage des bits et le mappage des symboles afin d'améliorer davantage le transmetteur FTN-OQAM. Les résultats présentés révèlent le potentiel important des systèmes proposésThe exponential growth of wireless data traffic driven by mobile Internet and smart devices constrains the future radio systems to include advanced modulations/waveforms offering higher data rates with more efficient bandwidth usage. One possibility is to violate the well known Nyquist criterion by transmitting faster than the Nyquist rate, i.e., using a technique also known as Faster-Than-Nyquist (FTN) signaling. Nyquist-based systems have the advantage of simple transmitter and receiver architectures at the detriment of bandwidth efficiency. The idea of signaling beyond the Nyquist rate to trade the interference-free transmission for more throughput goes back to 1975. In this dissertation, we investigate the concept of FTN signaling over Additive White Gaussian Noise (AWGN) channel in the context of Orthogonal Frequency Division Multiplexing with Offset Quadrature Amplitude Modulation OFDM/OQAM modulation.The main objective of our work is to present an OFDM/OQAM system signaling faster than the Nyquist one and explore its potential rate improvement while keeping under consideration the overall system complexity. First, we propose a new efficient FTN implementation of OFDM/OQAM systems, denoted by FTN-OQAM, that has the same complexity as OFDM/OQAM systems, while approaching very closely the FTN theoretical rate improvement. As the Nyquist condition is no longer respected, severe interference impacts the transmitted signals. To deal with the introduced interferences, we propose a turbo-like receiver based on Minimum Mean Square Error Linear Equalization and Interference Cancellation, named MMSE LE-IC. The aim of our system is to boost the transmission rate, which means that high constellation orders will be targeted. In this respect, the MMSE LE-IC, whose complexity is independent of the constellation, turns out to be a good candidate. Since OFDM/OQAM modulation can be equipped with different types of pulse shapes, we propose an algorithm to find, for different constellation orders, the minimum achieved FTN packing factor for various pulse shapes. Then, we aim at improving the iterative processing of the introduced transceiver. The proposed method involves combining a precoder with the FTN-OQAM system in order to remove FTN-induced interference at the transmitter. We also present a sparse precoding pattern as it is difficult to jointly precode all the transmitted symbols. We introduce three families of precoders along with the corresponding receivers. Furthermore, we propose several modifications of the FTN-OQAM transmitter concerning different blocks such as channel coding, bits mapping and symbols mapping to further enhance the FTN-OQAM transceiver design. Presented results reveal the significant potential of the proposed methods
10
Shaat, Musbah M. R. "Resource Management in Multicarrier Based Cognitive Radio Systems." Doctoral thesis, Universitat Politècnica de Catalunya, 2012. http://hdl.handle.net/10803/81300.
Full textAbstract:
The ever-increasing growth of the wireless application and services affirms the importance of the effective usage of the limited radio spectrum. Existing spectrum management policies have led to significant spectrum under-utilization. Recent measurements showed that large range of the spectrum is sparsely used in both temporal and spatial manner. This conflict
between the inefficient usage of the spectrum and the continuous evolution in the wireless communication calls upon the development of more flexible management policies. Cognitive radio (CR) with the dynamic spectrum access (DSA) is considered to be a key technology in making the best solution of this conflict by allowing a group of secondary users (SUs) to share the radio spectrum originally allocated to the primary user (PUs). The operation of CR should not negatively alter the performance of the PUs. Therefore, the interference control along with the highly dynamic nature of PUs activities open up new resource allocation problems in CR systems. The resource allocation algorithms should ensure an effective share of the temporarily available frequency bands and deliver the solutions in timely fashion to cope with quick changes in the network.
In this dissertation, the resource management problem in multicarrier based CR systems is considered. The dissertation focuses on three main issues: 1) design of efficient resource allocation algorithms to allocate subcarriers and powers between SUs such that no harmful interference is introduced to PUs, 2) compare the spectral efficiency of using different multicarrier schemes in the CR physical layer, specifically, orthogonal frequency division multiplexing (OFDM) and filter bank multicarrier (FBMC) schemes, 3) investigate the impact of the different constraints values on the overall performance of the CR system.
Three different scenarios are considered in this dissertation, namely downlink transmission, uplink transmission, and relayed transmission. For every scenario, the optimal solution is examined and efficient sub-optimal algorithms are proposed to reduce the computational burden of obtaining the optimal solution. The suboptimal algorithms are developed by separate the subcarrier and power allocation into two steps in downlink and uplink scenarios. In the relayed scenario, dual decomposition technique is used to obtain an asymptotically optimal solution, and a joint heuristic algorithm is proposed to find the suboptimal solution. Numerical simulations show that the proposed suboptimal algorithms achieve a near optimal performance and perform better than the existing algorithms designed for cognitive and non-cognitive systems. Eventually, the ability of FBMC to overcome the OFDM drawbacks and achieve more spectral efficiency is verified which recommends the consideration of FBMC in the future CR systems.El crecimiento continuo de las aplicaciones y servicios en sistemas inal´ambricos, indica la importancia y necesidad de una utilizaci´on eficaz del espectro radio. Las pol´ıticas actuales de gesti´on del espectro han conducido a una infrautilizaci´on del propio espectro radioel´ectrico. Recientes mediciones en diferentes entornos han mostrado que gran parte del espectro queda poco utilizado en sus ambas vertientes, la temporal, y la espacial. El permanente conflicto entre el uso ineficiente del espectro y la evoluci´on continua de los sistemas de comunicaci´on inal´ambrica, hace que sea urgente y necesario el desarrollo de esquemas de gesti´on del espectro m´as flexibles. Se considera el acceso din´amico (DSA) al espectro en los sistemas cognitivos como una tecnolog´ıa clave para resolver este conflicto al permitir que un grupo de usuarios secundarios (SUs) puedan compartir y acceder al espectro asignado inicialmente a uno o varios usuarios primarios (PUs). Las operaciones de comunicaci´on llevadas a cabo por los sistemas radio cognitivos no deben en ning´un caso alterar (interferir) los sistemas primarios. Por tanto, el control de la interferencia junto al gran dinamismo de los sistemas primarios implica nuevos retos en el control y asignaci´on de los recursos radio en los sistemas de comunicaci´on CR. Los algoritmos de gesti´on y asignaci´on de recursos (Radio Resource Management-RRM) deben garantizar una participaci´on efectiva de las bandas con frecuencias disponibles temporalmente, y ofrecer en cada momento oportunas soluciones para hacer frente a los distintos cambios r´apidos que influyen en la misma red. En esta tesis doctoral, se analiza el problema de la gesti´on de los recursos radio en sistemas multiportadoras CR, proponiendo varias soluciones para su uso eficaz y coexistencia con los PUs. La tesis en s´ı, se centra en tres l´ıneas principales: 1) el dise˜no de algoritmos eficientes de gesti´on de recursos para la asignaci´on de sub-portadoras y distribuci´on de la potencia en sistemas segundarios, evitando asi cualquier interferencia que pueda ser perjudicial para el funcionamiento normal de los usuarios de la red primaria, 2) analizar y comparar la eficiencia espectral alcanzada a la hora de utilizar diferentes esquema de transmisi´on multiportadora en la capa f´ısica del sistema CR, espec´ıficamente en sistemas basados en OFDM y los basados en banco de filtros multiportadoras (Filter bank Multicarrier-FBMC), 3) investigar el impacto de las diferentes limitaciones en el rendimiento total del sistema de CR. Los escenarios considerados en esta tesis son tres, es decir; modo de transmisi´on descendente (downlink), modo de transmisi´on ascendente (uplink), y el modo de transmisi´on ”Relay”. En cada escenario, la soluci´on ´optima es examinada y comparada con algoritmos sub- ´optimos que tienen como objetivo principal reducir la carga computacional. Los algoritmos sub-´optimos son llevados a cabo en dos fases mediante la separaci´on del propio proceso de distribuci´on de subportadoras y la asignaci´on de la potencia en los modos de comunicaci´on descendente (downlink), y ascendente (uplink). Para los entornos de tipo ”Relay”, se ha utilizado la t´ecnica de doble descomposici´on (dual decomposition) para obtener una soluci´on asint´oticamente ´optima. Adem´as, se ha desarrollado un algoritmo heur´ıstico para poder obtener la soluci´on ´optima con un reducido coste computacional. Los resultados obtenidos mediante simulaciones num´ericas muestran que los algoritmos sub-´optimos desarrollados logran acercarse a la soluci´on ´optima en cada uno de los entornos analizados, logrando as´ı un mayor rendimiento que los ya existentes y utilizados tanto en entornos cognitivos como no-cognitivos. Se puede comprobar en varios resultados obtenidos en la tesis la superioridad del esquema multiportadora FBMC sobre los sistemas basados en OFDM para los entornos cognitivos, causando una menor interferencia que el OFDM en los sistemas primarios, y logrando una mayor eficiencia espectral. Finalmente, en base a lo analizado en esta tesis, podemos recomendar al esquema multiportadora FBMC como una id´onea y potente forma de comunicaci´on para las futuras redes cognitivas.
Book chapters on the topic "Ofdm/oqam"
1
Tarun Kumar, J., Chakradhar Adupa, V. Sandeep Kumar, Shyamsunder Merugu, and Kasanagottu Srinivas. "Channel Estimation for Broadband Wireless Access OFDM/OQAM System." In Data Engineering and Communication Technology, 353–60. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-0081-4_35.
Full text
2
Sandeep Kumar, V., J. Tarun Kumar, Shyamsunder Merugu, and Kasanagottu Srinivas. "PAPR Reduction Scheme for OFDM/OQAM Signals Using Novel Phase Sequence." In Data Engineering and Communication Technology, 211–19. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-0081-4_22.
Full text
3
Zorba, Nizar, Stephan Pfletschinger, and Faouzi Bader. "Increasing the Performance of OFDM-OQAM Communication Systems through Smart Antennas Processing." In Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 315–24. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-03819-8_30.
Full text
4
Sandeep Kumar, V. "Improved Peak-to-Average Power Ratio Reduction Method for OFDM/OQAM System." In Advances in Intelligent Systems and Computing, 695–705. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-33-4299-6_57.
Full text
5
Thota, Sravanti, Yedukondalu Kamatham, and Chandra Sekhar Paidimarry. "Comparison of PAPR in OFDM and FBMC/OQAM Using PAPR Reduction Methods." In Data Engineering and Communication Technology, 535–42. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-0081-4_54.
Full textConference papers on the topic "Ofdm/oqam"
1
Javaudin, Jean-Philippe, and Yiqi Jiang. "Channel estimation in MIMO OFDM/OQAM." In 2008 IEEE 9th Workshop on Signal Processing Advances in Wireless Communications. IEEE, 2008. http://dx.doi.org/10.1109/spawc.2008.4641611.
Full text
2
Aoude, Mohamad, Robert Vallet, and Slobodan Nedic. "Interference cancellation in coded OFDM/OQAM." In 2012 9th International Symposium on Wireless Communication Systems (ISWCS 2012). IEEE, 2012. http://dx.doi.org/10.1109/iswcs.2012.6328354.
Full text
3
Mao, Junying, Xi Fang, Yueyang Yu, Ding Ding, Lei Zhang, and Guiqiu Jiang. "Comparison of OFDM and OFDM/OQAM Systems in Nonlinear Interference." In 2020 12th International Conference on Communication Software and Networks (ICCSN). IEEE, 2020. http://dx.doi.org/10.1109/iccsn49894.2020.9139107.
Full text
4
Jahan, B., M. Lanoiselee, G. Degoulet, and R. Rabineau. "Full Synchronization Method for OFDM/OQAM and OFDM/QAM Modulations." In 2008 IEEE 10th International Symposium on Spread Spectrum Techniques and Applications (ISSSTA). IEEE, 2008. http://dx.doi.org/10.1109/isssta.2008.69.
Full text
5
Lin, Bangjiang, Xuan Tang, Zabih Ghassemlooy, Chun Lin, Zhenlei Zhou, and Haiguang Zhang. "OFDM/OQAM for MIMO Visible Light Communications." In 2018 Asia Communications and Photonics Conference (ACP). IEEE, 2018. http://dx.doi.org/10.1109/acp.2018.8596000.
Full text
6
Abdoli, Mohammad Javad, Ming Jia, and Jianglei Ma. "Weighted circularly convolved filtering in OFDM/OQAM." In 2013 IEEE 24th Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC). IEEE, 2013. http://dx.doi.org/10.1109/pimrc.2013.6666218.
Full text
7
El Tabach, M., J. P. Javaudin, and M. Helard. "Spatial Data Multiplexing Over OFDM/OQAM Modulations." In 2007 IEEE International Conference on Communications. IEEE, 2007. http://dx.doi.org/10.1109/icc.2007.693.
Full text
8
Mattera, Davide, Mario Tanda, and Maurice Bellanger. "Frequency-spreading implementation of OFDM/OQAM systems." In 2012 9th International Symposium on Wireless Communication Systems (ISWCS 2012). IEEE, 2012. http://dx.doi.org/10.1109/iswcs.2012.6328353.
Full text
9
Jamal, Hosseinali, and David W. Matolak. "Dual-Polarization OFDM-OQAM Wireless Communication System." In 2018 IEEE 88th Vehicular Technology Conference (VTC-Fall). IEEE, 2018. http://dx.doi.org/10.1109/vtcfall.2018.8690765.
Full text
10
Du, Jinfeng, and Svante Signell. "Pulse shape adaptivity in OFDM/OQAM systems." In the 2008 International Conference. New York, New York, USA: ACM Press, 2008. http://dx.doi.org/10.1145/1509315.1509446.
Full text