Gotowe bibliografie tematyczne / OFDM

Gotowa bibliografia na temat „OFDM”

Autor: Grafiati
Data publikacji: 4 czerwca 2021
Data aktualizacji: 25 maja 2024

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Artykuły w czasopismach na temat "OFDM"

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БОЙКО, Юлій, i Ілля ПЯТІН. "СХЕМОТЕХНІЧНІ АСПЕКТИ ЗАБЕЗПЕЧЕННЯ УМОВ СИНХРОНІЗАЦІЇ В СИСТЕМАХ ЗВ’ЯЗКУ З OFDM". MEASURING AND COMPUTING DEVICES IN TECHNOLOGICAL PROCESSES, nr 1 (30.03.2023): 28–37. http://dx.doi.org/10.31891/2219-9365-2023-73-1-5.

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В запропонованій роботі розглянуто схемотехнічні аспекти забезпечення умов синхронізації в системах зв’язку з OFDM. Наведено дослідження оцінок міжканальних та міжсимвольних завад в системах синхронізації. Описано та алгоритмізовано можливі сценарії оцінки завад в каналах з OFDM за навчальними послідовностями та пілот-сигналами. Наведено експериментальні результати оцінки спотворення OFDM-сигналів в умовах міжканальних завад на основі сигналів типу 16QAM. Здійснено порівняльний аналіз середньоквадратичної оцінки міжканальних завад для трьох методів синхронізації які досліджувались у статті. Розглянуто конструкції OFDМ-сигналів з пілот-сигналами. Досліджено концепції схемотехнічної реалізації систем тактової синхронізації в каналі зв’язку з OFDM. Проілюстровано процес спрацювання системи синхронізації з метою компенсації спотворень на основі сформованої сітки ресурсів в каналі зв’язку з OFDM.
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B., Archana, i T. P. Surekha. "Integrated approach for efficient power consumption and resource allocation in MIMO-OFDMA". International Journal of Electrical and Computer Engineering (IJECE) 10, nr 2 (1.04.2020): 2069. http://dx.doi.org/10.11591/ijece.v10i2.pp2069-2076.

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The growing interest towards wireless communication advancement with smart devices has provided the desired throughput of wireless communication mechanisms. But, attaining high-speed data packets amenities is the biggest issue in different multimedia applications. Recently, OFDM has come up with the useful features for wireless communication however it faces interference issues at carrier level (intercarrier interferences). To resolve these interference issues in OFDM, various existing mechanisms were utilized cyclic prefix, but it leads to redundancy in transmitted data. Also, the transmission of this redundant data can take some more power and bandwidth. All these limitations factors can be removed from a parallel cancellation mechanism. The integration of parallel cancellation and Convolution Viterbi encoding and decoding in MIMO-OFDMA will be an effective solution to have high data rate which also associations with the benefits of both the architectures of MIMO and OFDMA modulation approaches. This paper deals with this integrated mechanism for efficient resource allocation and power consumption. For performance analysis, MIMO-OFDMA system is analyzed with three different approaches likeMIMO-OFDM system without parallel cancellation (MIMO-OFDMA-WPC), MIMO-OFDMA System with parallel cancellation (MIMO-OFDMA-PC) and proposed IMO-OFDMA system with parallel cancellation and Convolution Viterbi encoding/decoding (pMIMO-OFDMA-PC &CVed) for 4x4 transmitter and receiver. Through performance analysis, it is found that the proposed system achieved better resource allocation (bandwidth) with high data rate by minimized BER rate and achieved least power consumption with least BER.
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Et.al, G. Jagga Rao. "Milli meter Wave MIMO-OFDMA Scheme with MMSE-based VEMF in 6G Wireless Technology". Turkish Journal of Computer and Mathematics Education (TURCOMAT) 12, nr 3 (10.04.2021): 4701–7. http://dx.doi.org/10.17762/turcomat.v12i3.1890.

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Millimetre Wave (MmWave) massive multiple-input multiple-output (MmWave-massive-MIMO) has developed as beneficial for gigabit-per-second data broadcast into 6G digitized wireless technology. The collection of low-rate and energy-efficient (EE) types of machinery, low power consumptions, multi-bit quantized massive MIMO-Orthogonal Frequency Division Multiplexing Access (OFDMA) structure have been planned for the receiver manner. The main concentration effort is the minimization of a state-of-the-art pilot-symbol quantized (PSQ) massive MIMO-OFDMA system (m-MIMO-OFDM-S). Accordingly, in this analysis, by minimizing many advantages of the Variational Estimated Message Fleeting (VEMF) algorithm. A modified low complexity manner VEMF algorithm is invented for the utilization of the ASQ-m-MIMO-OFDM-S structure. Hence, two new modules improve the energy efficiency and spectrum efficiency for wireless smart 6G technology of pilot bits allocation process for MmWave connections of the hybrid MIMO-OFDM receiver structural design. Several technologies such as massive MIMO-OFDMA, 3GPP & 4G& 5G technology, the device to device communication (D2D), GREEN communication have increasingly important consideration in assisting spectrum consumption along with power consumption during simulations. The proposed VEMF algorithm has achieved higher capacity, sum rate, Energy Efficiency (EE), and throughput for the receiver section. Finally, we present a greater number of user's data transmissions MmWave-massive-MIMO-OFDMA system.
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Eneh, T., P. Rapajic, K. Anang i Bello Lawal. "Adaptive MMSE Multiuser Detection in MIMO OFDM Wireless Communication System". Advanced Materials Research 367 (październik 2011): 233–40. http://dx.doi.org/10.4028/www.scientific.net/amr.367.233.

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The combination of MIMO signal processing with OFDM is a solution to achieving high data rates for next generation wireless communication systems operating in frequency selective fading environments. To realize the extension of the MIMO with OFDM, a number of changes are required in the baseband signal processing. The developed adaptive Multiuser Detection in MIMO OFDM(AMUD) scheme performs better compared to non adaptive MIMO OFDM, at low Signal to noise ratio (SNR), it shows good performance in computational complexity, bit error rate (BER) and capacity. Simulation results show that the developed algorithm sum rate capacity is very close to MIMO theoretical upper bound (21.5 bits/s/Hz at signal to noise ratio of 20dB) which strongly indicate it’s applicability to the uplink channel where power transmission at the mobile station is a constraint. The BER performance of the developed scheme shows that, as the number of antenna increases, the 8 x 8 AMUD provides a 2dB gain compared to known non adaptive MIMO OFDMO at low SNR.
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Lopes, Alberto A., José Seguro, Paulo Gomes, Nuno Souto i Américo Correia. "Interference Coordination for E-MBMS Transmissions in LTE-Advanced". International Journal of Digital Multimedia Broadcasting 2010 (2010): 1–11. http://dx.doi.org/10.1155/2010/689705.

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Interference coordination methods for Evolved-Multimedia Broadcast/Multicast Service (E-MBMS) in Long-Term Evolution Advanced (LTE-A) are presented. In addition, we consider signal space diversity based on Rotation Matrices (RM) known to provide good performance gains over uncorrelated Rayleigh fading channels. OFDM/OFDMA systems can make the use of RM very attractive both for single and multiple antenna transmissions. In this paper, OFDM/OFDMA signals based on LTE parameters are combined with RM, MIMO, Turbo, or LDPC codes. We have considered different types of receivers, namely, we used an MMSE (Minimum Mean Squared Error) equalizer and a Maximum Likelihood Soft Output criterion (MLSO). Frequency, signal, and space diversity gains are evaluated for different spatial channel models (SCM) based on ITU multipath propagation channels. Different adaptive frequency reuse and schedulers are considered to evaluate the E-MBMS spectral efficiency at the cell borders.
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Sergeev, A. M., i N. Sh Blaunstein. "Evolution of multiple-access networks cellular and non-cellular — in historical perspective. Part 1". Information and Control Systems, nr 4 (23.09.2018): 86–104. http://dx.doi.org/10.31799/1684-8853-2018-4-86-104.

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Introduction:The goal of this review is the analysis of evolution of the current and novel wireless networks, from secondgeneration (2D)tofifth generation(5G),as well as changes in technologies and their corresponding theoretical background andprotocols -from Bluetooth, WLAN, WiFi and WiMAXtoLTE, OFDM/OFDMA, MIMO and LTE/MIMO advanced technologies with new hierarchy of cellular maps design — femto/pico/micro/macro.Methods:We use new theoretical frameworkstodescribe advanced technologies, such as multicarrier diversity technique, OFDM and OFDM novel approach, new aspects ofMIMO description based on multi-beam antennas, design of various cellular maps based on new algorithms of femto/pico/micro/macrocell deployment, and the methodology of a new MIMO/LTE system integration based on multi-beam antennas.Results:We have created a new methodology for multi-carrier diversity description of novel multiple-access networks, forthe usage of OFDM/OFDMA modulation in ordertoovercome inter-user and inter-symbol interference in multiple-access networks, as well as multiplicative noises in multiple-access wireless networks caused by multi-ray phenomena. Finally, wehave suggested howtoovercome the propagation effects occurring in the terrestrial communication channels by using acombination of MIMO and LTE technologies based on multi-beam antennas. For these purposes, we present a new stochasticapproach which takes into account the terrain features, such as buildings' overlay profile, buildings' density around the base station and each user's antennas, andsoforth. These parameters allow ustoestimate the effects of fading as a multiplicativenoise source.Practical relevance:The new methodology of estimating the effects created by multiplicative noise and inter-user and inter-symbol interference in terrestrial wireless networks allows ustopredict a-priory practical aspects of the currentand new multiple-access wireless communication systems, like the potential number of users or the spectral efficiency ofuser channels for various configurations of cell deployment: femto, pico, micro, and macro, as well as the novel MIMO/LTE system configurations for future networks of the 4th and 5th generations.
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Hong, Huandong, i Zhengquan Li. "Hybrid Adaptive Bias OFDM-Based IM/DD Visible Light Communication System". Photonics 8, nr 7 (5.07.2021): 257. http://dx.doi.org/10.3390/photonics8070257.

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Conventional optical orthogonal frequency division multiplexing (OFDM) schemes, such as adaptively biased optical OFDM (ABO-OFDM) and hybrid asymmetrically clipped optical OFDM (HACO-OFDM), are unable to tap all the resources of the subcarriers and only achieve relatively high power efficiency. In this paper, a hybrid adaptive bias optical OFDM (HABO-OFDM) scheme for visible light communication (VLC) is proposed to improve spectral efficiency and power efficiency. In the proposed HABO-OFDM scheme, different optical OFDM components are combined for transmission at the same time, and the adaptive bias is designed to ensure the non-negativity, as well as obtaining significantly high power efficiency. Meanwhile, the implementation complexity of the HABO-OFDM receiver is notably lower than the conventional superimposed optical OFDM schemes. Simulation results show that the proposed HABO-OFDM scheme outperforms ABO-OFDM and HACO-OFDM in terms of both peak-to-average-power ratio (PAPR) and power efficiency. The PAPR performance of HABO-OFDM is about 3.2 dB lower than that of HACO-OFDM and 1.7 dB lower than that of ABO-OFDM. Moreover, we can see that the Eb(elec)/N0 required for HABO-OFDM to reach the BER target is lower than the other two schemes at the Bit rate/Normalized bandwidth range of 3.5 to 8.75, which means that the power efficiency of HABO-OFDM is higher in this range.
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Chen, Chien Sheng, Yung Chuan Lin, He Nian Shou i Chi Tien Sun. "Compensation of Phase Noise Effects for IEEE 802.16e OFDMA Systems". Advanced Materials Research 204-210 (luty 2011): 1330–35. http://dx.doi.org/10.4028/www.scientific.net/amr.204-210.1330.

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Orthogonal frequency division multiplexing (OFDM) system which provides high spectral efficiency has obvious advantages in robustness against the multipath delay spread and the fading channel. One of the major disadvantages of such a multi-carrier modulated system is the sensitivity of its performance to synchronization error, such as phase noise and frequency offset. Phase noise is caused by the mismatch between the transmitter and the receiver oscillators. Phase noise in an OFDM system can destroy the orthogonality of the subcarriers and cause inter-carrier interference (ICI). Phase noise resulting in common phase error (CPE) and Inter-Carrier Interference is a critical challenge to the implementation of OFDM systems. In this paper, the phase noise effects of the IEEE 802.16e OFDMA systems are compensated. The practical cluster-based method which is used to estimate either the CPE or the ICI coefficients in the fading channel and compensate the effects of phase error is also proposed. Numerical results demonstrate that the proposed algorithm can effectively improve the performance caused by phase noise.
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Gebeyehu, Zelalem Hailu, Philip Kibet Langat i Ciira Wa Maina. "BER Performance of Stratified ACO-OFDM for Optical Wireless Communications over Multipath Channel". Journal of Computer Networks and Communications 2018 (2018): 1–14. http://dx.doi.org/10.1155/2018/9575281.

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In intensity modulation/direct detection- (IM/DD-) based optical OFDM systems, the requirement of the input signal to be real and positive unipolar imposes a reduction of system performances. Among previously proposed unipolar optical OFDM schemes for optical wireless communications (OWC), asymmetrically clipped optical OFDM (ACO-OFDM) and direct current biased optical OFDM (DCO-OFDM) are the most accepted ones. But those proposed schemes experience either spectral efficiency loss or energy efficiency loss which is a big challenge to realize high speed OWC. To improve the spectral and energy efficiencies, we previously proposed a multistratum-based stratified asymmetrically clipped optical OFDM (STACO-OFDM), and its performance was analyzed for AWGN channel. STACO-OFDM utilizes even subcarriers on the first stratum and odd subcarriers on the rest of strata to transmit multiple ACO-OFDM frames simultaneously. STACO-OFDM provides equal spectral efficiency as DCO-OFDM and better spectral efficiency compared to ACO-OFDM. In this paper, we analyze the BER performance of STACO-OFDM under the effect of multipath fading. The theoretical bit error rate (BER) bound is derived and compared with the simulation results, and good agreement is achieved. Moreover, STACO-OFDM shows better BER performance compared to ACO-OFDM and DCO-OFDM.
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Zhang, Xu, Yu Fang Zhou, Yin Peng Yu, Peng Chao Han i Xiao Rui Wang. "Comparison and Analysis of DCO-OFDM, ACO-OFDM and ADO-OFDM in IM/DD Systems". Applied Mechanics and Materials 701-702 (grudzień 2014): 1059–62. http://dx.doi.org/10.4028/www.scientific.net/amm.701-702.1059.

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As a promising modulation technology for optical communication, Orthogonal Frequency Division Multiplexing (OFDM) is now increasingly used and a lot of ways of improving the optical efficiency of Intensity Modulated/ Direct Detection (IM/DD) systems have been proposed. And real and non-negative OFDM signals are required in this kind of system. Asymmetrically clipped DC biased Optical OFDM (DCO-OFDM), Asymmetrically Clipped Optical OFDM (ACO-OFDM) and Asymmetrically clipped DC biased Optical OFDM (ADO-OFDM) can satisfy this requirement. In this paper, we analysis the properties and performance orderly of the above three systems and simultaneously compare their performance. The simulation results show that DCO-OFDM is efficient in terms of bandwidth while the ACO-OFDM is efficient in terms of optical power. More importantly, ADO-OFDM is both power-efficient and bandwidth-efficient. At the same time, a developmentally proposal for the future OFDM in IM/DD systems is put forward.
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Rozprawy doktorskie na temat "OFDM"

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Nowak, Dan. "Adaptivní OFDM". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2011. http://www.nusl.cz/ntk/nusl-219140.

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The purpose of this paper is to study the possibilities of the OFDM system adaptive modulation. The study presents mechanism for acquiring the necessary data of every frequency subchannel using pilot signals and application of these data for system adjustment. The paper introduces the water-filling principle for subchannel power allocation on the basis of their SNR and adaptive modulation mechanisms for variety of OFDM usage. These mechanisms are implemented into a MATLAB model. The code is then transformed into graphical representation and using USRP2, the signal is transmitted by real world channel.
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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.

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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.
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Wang, Tiejun. "Mobile OFDM communications". Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2006. http://wwwlib.umi.com/cr/ucsd/fullcit?p3211276.

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Thesis (Ph. D.)--University of California, San Diego, 2006.
Title from first page of PDF file (viewed June 7, 2006). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 104-111).
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Armour, Simon Martin Daniel. "Combined OFDM-equalisation". Thesis, University of Bristol, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369530.

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Xu, Lei. "OFDM turbo transceivers". Thesis, University of Southampton, 2008. https://eprints.soton.ac.uk/64480/.

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In this thesis a variety of different techniques designed for the sake of improving the attainable efficiency of wireless system are considered in the context of Orthogonal Frequency Division Multiplexing (OFDM). More explicitly, powerful turbo transceivers invoking Sphere Packing (SP) modulation are designed using EXtrinsic Information Transfer (EXIT) charts for both single-user and multi-user transmission. In order to provide an attractive suite of single-user OFDM transceivers, we contrive a SP-aided OFDM scheme for maximizing the achievable coding advantage. The corresponding capacity equation shows that the SP-OFDM scheme exhibits a higher capacity than its counterpart dispensing with SP. Furthermore, a carefully designed Sphere Packing symbol To Sub-Carrier Mapping (SPTSCM) scheme is contrived, which results in an improved Discrete Input Continuous Output Memoryless Channel (DCMC) capacity. This is achieved by reducing the correlation between the multiple OFDM sub-carriers conveying a specific SP symbol. In order to enhance the attainable BER performance of the SP-OFDM scheme, iterative detection is invoked for exchanging extrinsic information between the SP symbol-to-bit demapper and the channel decoder. In contrast to the classic SP signal construction, sophisticated SP schemes are designed with the aid of EXIT charts for the sake of improving the convergence behaviour of the iteratively detected schemes. Explicitly, an approximately 0.15bit/s/Hz DCMC capacity improvement is achieved and the proposed iterative detection aided SP-OFDM scheme becomes capable of performing within 2.1dB of the maximum achievable rate limit obtained using EXIT charts at BER = 10−4. Some of the proposed advances are then extended to a multi-user Space Division Multiple Access (SDMA) OFDM scheme. Novel turbo MUDs are designed and investigated in terms of their complexity, EXIT characteristics and BER performance. More explicitly, the linear turbo MUDs considered include the Complex-valued Minimum Mean Square Error (SIC-CMMSE) scheme, the Soft Interference Cancellation based Real-valued Minimum Mean Square Error (SIC-RMMSE) arrangement and the Soft Interference Cancellation based Minimum Bit-Error Rate (SIC-MBER) MUD schemes. The SIC-RMMSE is only applicable in the context of BPSK modulated schemes. A Reduced-complexity Minimum Bit-Error Rate (RMBER) is also designed for the sake of arriving at a complexity reduction by slightly compromising the attainable performance in comparison to the SIC-MBER MUD. Furthermore, a hybrid scheme was designed to eliminate the performance degradation imposed by the RMBER MUD. In contrast to above-mentioned linear schemes, Bayesian turbo MUD and the K-best iterative Sphere Decoder (SD) belong to the family of non-linear MUDs. Then a general complexityreduction technique was contrived in order to reduce the complexity imposed by the turbo MUDs, which was referred to as the A-priori-LLR-Threshold (ALT) aided MUD algorithm, which was introduced for the sake of striking an attractive trade-off between the attainable complexity-reduction and the performance degradation imposed. Finally, the novel framework of Transmit Domain Processing based Detectors (TDPD) was contrived for a generalized multi-access or multiplexing based channel model in order to circumvent the exponentially increasing complexity imposed by the Maximum Likelihood (ML) MUD as a function of both the number of antennas and the number of bits per symbol. Explicitly, the TDPD may be separated into three basic steps including the MUD’s Search Center (SC) calculation, detection candidate list generation and LLR output calculation. A range of different schemes were considered for each of the three steps, and the SIC-CMMSE SC aided hybrid K-best subset combination based iterative TDPD was capable of achieving a similar BER performance to the optimal ML detector at a significantly reduced-complexity.
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Gui, Bo. "Cooperative OFDM networking". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 156 p, 2009. http://proquest.umi.com/pqdweb?did=1654493791&sid=1&Fmt=2&clientId=8331&RQT=309&VName=PQD.

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Skrzypczak, Alexandre. "Contribution à l'étude des modulations multiporteuses OFDM / OQAM et OFDM suréchantillonnées". Rennes 1, 2007. http://www.theses.fr/2007REN1S136.

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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 réalisée
Nowadays, 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
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Serener, Ali. "Optimization of short block length LDPC codes for OFDM and spread OFDM /". Search for this dissertation online, 2005. http://wwwlib.umi.com/cr/ksu/main.

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Karampatsis, Dimitrios. "Modelling and performance assessment of OFDM and fast-OFDM wireless communication systems". Thesis, University College London (University of London), 2004. http://discovery.ucl.ac.uk/1446778/.

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This thesis is mainly concerned with the design, modelling and performance assessment of modulation techniques for use in wireless communication systems. The work is divided, broadly in three areas; a multimode system proposal, an assessment of a new modulation scheme and a system optimisation technique. A multimode system architecture employing GSM and EDGE systems and an Orthogonal Frequency Division Multiplexing (OFDM) system is proposed. The OFDM system is designed to have similar frame structure, channel allocation and spectrum shape to those of the GSM and EDGE systems. The multimode system is evaluated under typical multipath fading environments specified for GSM/EDGE and adjacent-channel and co-channel interference. The results indicated that the proposed OFDM system can be perfectly integrated within the GSM/EDGE network core. Furthermore, a novel modulation technique is investigated. Fast-OFDM (FOFDM) is a variation of OFDM, which offers twice the bandwidth efficiency when compared to OFDM. However, the bandwidth efficiency only applies to one dimensional modulation schemes (BPSK or M-ASK). The suitability of FOFDM for wireless communications is assessed by studying its performance under receiver front-end distortions and multipath fading environments. The performance of the FOFDM system is compared with the performance of a similar OFDM system. The results indicated that under small distortion conditions, the performance of FOFDM and OFDM is comparable. Finally, the effect of interpolation filtering on OFDM systems in noise limited and interference limited environments is investigated. The aim of this study is to highlight that interference should be taken into consideration when designing systems for wireless communications. In addition, this study can be utilised in software defined radio schemes, offering optimised performance. Overall, this thesis presents work over a range of research areas, providing system proposals, modulation comparisons and system optimisation techniques that can be used by developers of future mobile systems.
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Cheung, Bing-Leung Patrick. "Simulation of Adaptive Array Algorithms for OFDM and Adaptive Vector OFDM Systems". Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/34915.

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The increasing demand for high data rate services necessitates the adoption of very wideband waveforms. In this case, the channel is frequency-selective, that is, a large number of resolvable multipaths are present in this environment and fading is not highly correlated across the band. Orthogonal frequency division multiplexing (OFDM) is well-known to be effective against multipath distortion. It is a multicarrier communication scheme, in which the bandwidth of the channel is divided into subcarriers and data symbols are modulated and transmitted on each subcarrier simultaneously. By inserting guard time that is longer than the delay spread of the channel, an OFDM system is able to mitigate intersymbol interference (ISI). Deploying an adaptive antenna array at the receiver can help separate the desired signal from interfering signals which originate from different spatial locations. This enhancement of signal integrity increases system capacity. In this research, we apply adaptive array algorithms to OFDM systems and study their performance in a multipath environment with the presence of interference. A novel adaptive beamforming algorithm based on the minimum mean-squared error (MMSE) criterion, which is referred to as frequency-domain beamforming, is proposed that exploits the characteristics of OFDM signals. The computational complexity of frequency-domain beamforming is also studied. Simulation results show employing an adaptive antenna array with an OFDM system significantly improves system performance when interference is present. Simulations also show that the computational complexity of the algorithm can be reduced by half without significant performance degradation. Adaptive array algorithms based on the maximum signal-to-noise ratio (MSNR) and the maximum signal-to-interference-plus-noise ratio (MSINR) criteria are also applied to adaptive vector OFDM systems (AV-OFDM). Simulation results show that the adaptive algorithm based on the MSNR criterion has superior performance in the multipath environment but performs worse than the one based on the MSINR criterion under the flat fading channel.
Master of Science
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Książki na temat "OFDM"

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Rohling, Hermann, red. OFDM. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-17496-4.

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Bader, Faouzi, i Nizar Zorba. Advances on processing for multiple carrier schemes: OFDM & OFDMA. Hauppauge, N.Y: Nova Science Publishers, 2011.

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Engels, Marc, red. Wireless OFDM Systems. Boston: Kluwer Academic Publishers, 2002. http://dx.doi.org/10.1007/b117438.

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Hanzo, L., i T. Keller. OFDM and MC-CDMA. Chichester, UK: John Wiley & Sons, Ltd, 2006. http://dx.doi.org/10.1002/9780470031384.

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Shieh, William. OFDM for optical communications. Amsterdam: Academic Press, 2010.

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Ivan, Djordjevic, red. OFDM for optical communications. Burlington, MA: Academic Press/Elsevier, 2010.

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Ramjee, Prasad, red. OFDM wireless multimedia communications. Boston: Artech House, 2000.

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Narasimhamurthy, Adarsh B., Mahesh K. Banavar i Cihan Tepedelenlioğlu. OFDM Systems for Wireless Communications. Cham: Springer International Publishing, 2010. http://dx.doi.org/10.1007/978-3-031-01513-7.

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Liu, Hui, i Guoqing Li. OFDM-Based Broadband Wireless Networks. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2005. http://dx.doi.org/10.1002/0471757195.

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Cheng, Xilin, Liuqing Yang i Xiang Cheng. Cooperative OFDM Underwater Acoustic Communications. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-33207-9.

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Części książek na temat "OFDM"

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Diniz, Paulo S. R., Wallace A. Martins i Markus V. S. Lima. "OFDM". W Block Transceivers, 55–103. Cham: Springer International Publishing, 2012. http://dx.doi.org/10.1007/978-3-031-01677-6_3.

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Abbas, Karim. "OFDM". W From Algorithms to Hardware Architectures, 197–253. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-08693-9_7.

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Yang, Sung-Moon Michael. "OFDM Signals". W Modern Digital Radio Communication Signals and Systems, 247–319. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-57706-3_5.

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Yu, Jianjun, i Nan Chi. "Optical OFDM". W Digital Signal Processing In High-Speed Optical Fiber Communication Principle and Application, 303–33. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-3098-2_12.

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Ansari, Nirwan, i Jingjing Zhang. "OFDM PON". W Media Access Control and Resource Allocation, 67–73. New York, NY: Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-3939-4_6.

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Li, Tongtong, Tianlong Song i Yuan Liang. "Securely Precoded OFDM". W Wireless Communications under Hostile Jamming: Security and Efficiency, 121–54. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-0821-5_5.

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Yu, Jianjun, i Nan Chi. "Direct Detection OFDM". W Digital Signal Processing In High-Speed Optical Fiber Communication Principle and Application, 335–71. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-3098-2_13.

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Terré, Michel, Mylène Pischella i Emmanuelle Vivier. "OFDM and LTE". W Wireless Telecommunication Systems, 95–127. Hoboken, NJ USA: John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118625422.ch4.

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Pejanovic-Djurisic, Milica, Enis Kocan i Ramjee Prasad. "OFDM Relay Systems". W Ofdm Based Relay Systems for Future Wireless Communications, 33–57. New York: River Publishers, 2022. http://dx.doi.org/10.1201/9781003338970-3.

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Ergen, Mustafa. "Principles of OFDM". W Mobile Broadband, 109–75. Boston, MA: Springer US, 2008. http://dx.doi.org/10.1007/978-0-387-68192-4_4.

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Streszczenia konferencji na temat "OFDM"

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"OFDM/OFDMA — WCN-04". W 2009 Fourth International Conference on Communications and Networking in China (CHINACOM). IEEE, 2009. http://dx.doi.org/10.1109/chinacom.2009.5339926.

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Zhang, Long, Kaihui Wang, Jiaxuan Liu, Xiongwei Yang, Ming Chen, Chen Wang, Bohan Sang i in. "A low-complexity 64QAM-based probabilistically shaped OFDM for W-band RoF system". W Optical Fiber Communication Conference. Washington, D.C.: Optica Publishing Group, 2024. http://dx.doi.org/10.1364/ofc.2024.w2b.6.

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We experimentally demonstrated a low-complexity probabilistic shaping (PS) 64QAM-OFDM in an IM-DD-based W-band RoF System. After 45-km SSMF and 4-m wireless transmission, the experimental results show that its receiver sensitivity is better than that of uniformly distributed-OFDM (UD-OFDM).
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Abdullahi, Muhammad Bello. "Appraisal of OFDM for multi-carrier, high-speed data rate wireless communication networks". W The 19th International Conference on Modelling and Applied Simulation. CAL-TEK srl, 2019. http://dx.doi.org/10.46354/i3m.2019.mas.002.

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Orthogonal Frequency Division Multiplexing (OFDM) is used to achieve multi-carrier signals and high- Speed data rate in free space. OFDM-based systems operate in the hostile multipath radio environment, which allows efficient sharing of limited resources. This research work was designed, developed and simulated an OFDM System using the basic blocks of Simulink in MATLAB/Simulink software, to support multi-carrier, high-speed data rates. This was achieved in backing of collection and review of high-quality research papers, which reported the latest research developments in OFDM communications networks, and its applications in future wireless systems. The research work significantly increases the speed of data rate signals, and many critical problems associated with the applications of OFDM technologies in future wireless systems are still looking for efficient solutions. This would overcome the global issues and challenges facing the limited bandwidth in wireless communication network.
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Singhal, Sneha, i Dheeraj Kumar Sharma. "Comparative Analysis of Clipping-filtering, SLM and PTS for PAPR Reduction Technique in OFDM System". W International Conference on Women Researchers in Electronics and Computing. AIJR Publisher, 2021. http://dx.doi.org/10.21467/proceedings.114.32.

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Modulation scheme, orthogonal frequency division multiplexing (OFDM) uses multiple carriers to communicate and transmit data. It is used widely in wireless communication due to its numerous advantages. OFDM modulation is very advantageous as it reduces inter symbol interference, provides high data rate and it is not affected by narrow band effect. To operate OFDM effectively, its high value of peak to average power ratio should be reduced. In OFDM, power amplifier should be linear and accommodate amplitude variations to work efficiently. The high peak to average power ratio affects the performance of power amplifier.
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Wang, Kaihui, Jianjun Yu, Weiping Li, Junjie Ding, Feng Wang, Chen Wang, Wen Zhou i in. "OFDM-1024QAM transmission over 400m at THz band with Delta-Sigma-Modulation". W Optical Fiber Communication Conference. Washington, D.C.: Optica Publishing Group, 2023. http://dx.doi.org/10.1364/ofc.2023.th1i.2.

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For the first time, we successfully transmit 1.25GBaud OFDM-256QAM/1024QAM signals over 20km SMF and 400m wireless link at the terahertz band with 1-bit DSM. The BER of OFDM-256QAM/1024QAM can satisfy the FEC threshold of 3.8×10-3/4.0×10-2.
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Li, Yibin, Zixian Wei, Zhaoming Wang, Amjad Ali, Qian Li i H. Y. Fu. "On the Performance of High Spectral Efficiency CRIP OFDM Scheme over 15-m GI-POF". W Conference on Lasers and Electro-Optics/Pacific Rim. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/cleopr.2022.cmp9b_03.

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A combining real and imaginary parts (CRIP) OFDM is employed to a 15-m graded-index plastic optical fiber to experimentally achieve a higher spectral efficiency up to 11.7 bit/s/Hz than conventional OFDM with BER below 3.8×10-3.
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Singh, Kambam Bijen, Sheikh Wasmir Hussain, Telajala Venkata Mahendra i C. V. Rama Rao. "Implementation of OFDM and Pulsed-OFDM". W 2016 International Conference on Information Technology (ICIT). IEEE, 2016. http://dx.doi.org/10.1109/icit.2016.033.

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Chafii, Marwa, Yahya J. Harbi i Alister G. Burr. "Wavelet-OFDM vs. OFDM: Performance comparison". W 2016 23rd International Conference on Telecommunications (ICT). IEEE, 2016. http://dx.doi.org/10.1109/ict.2016.7500465.

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Elgala, Hany, i Thomas D. C. Little. "P-OFDM: Spectrally Efficient Unipolar OFDM". W Optical Fiber Communication Conference. Washington, D.C.: OSA, 2014. http://dx.doi.org/10.1364/ofc.2014.th3g.7.

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Zhang, Long, Kaihui Wang, Chen Wang, Junjie Ding, Ming Chen, Bohan Sang, Junting Shi i in. "Real-Time Demonstration of a Low-complexity PS Scheme for 130Gb/s WDM-OFDM-PON". W Optical Fiber Communication Conference. Washington, D.C.: Optica Publishing Group, 2023. http://dx.doi.org/10.1364/ofc.2023.w2b.10.

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We experimentally demonstrated a low-complexity probabilistic shaping scheme in a real-time 16QAM-OFDM-based WDM-PON. The PS-OFDM signal with a net rate of 131.88- Gb/s transmission over 25-km SSMF can be achieved with the BER less than 3.8×10-3.
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Raporty organizacyjne na temat "OFDM"

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Sandhiya, Pallavi, Nazrul Zaki, Rickey Satterfield, Steve Bundick, Keith Thompson i Charles Grant. A 10W Low Cost OFDM Transceiver (LCOT). Fort Belvoir, VA: Defense Technical Information Center, luty 2013. http://dx.doi.org/10.21236/ada582514.

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Chen, Bosi. Spectrum Regrowth for OFDM-based LTE and WIMAX Systems. Portland State University Library, styczeń 2000. http://dx.doi.org/10.15760/etd.601.

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Yerramalli, Srinivas, Milica Stojanovic i Urbashi Mitra. Partial FFT Demodulation: A Detection Method for Doppler Distorted OFDM Systems. Fort Belvoir, VA: Defense Technical Information Center, czerwiec 2010. http://dx.doi.org/10.21236/ada531988.

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Han, Jieying, Brett T. Walkenhorst i Enkuang D. Wang. Adaptive Modulation Schemes for OFDM and SOQPSK Using Error Vector Magnitude (EVM) and Godard Dispersion. Fort Belvoir, VA: Defense Technical Information Center, czerwiec 2014. http://dx.doi.org/10.21236/ada619898.

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Jacklin, Neil, i Zhi Ding. Modern modulation schemes : a linear programming based tone injection algorithm for PAPR reduction of OFDM and linearly precoded systems. Office of Scientific and Technical Information (OSTI), wrzesień 2012. http://dx.doi.org/10.2172/1055613.

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Moyon, Marc. Review ofDe grands defis mathematiques d'Euclide a Condorcet. Washington, DC: The MAA Mathematical Sciences Digital Library, listopad 2010. http://dx.doi.org/10.4169/loci003603.

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Montgomery, Karl. A Characterization of OFDMA Uplink Activation for Industrial Applications. Gaithersburg, MD: National Institute of Standards and Technology, 2024. http://dx.doi.org/10.6028/nist.ir.8506.

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Gottuk, D. T., J. L. Scheffey, F. W. Williams, J. E. Gott i R. J. Tabet. Optical Fire Detection (OFD) for Military Aircraft Hangars: Final Report on OFD Performance to Fuel Spill Fires and Optical Stresses. Fort Belvoir, VA: Defense Technical Information Center, maj 2000. http://dx.doi.org/10.21236/ada405478.

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Wylie, Marilynn, i Glenn Green. On the Performance of Serially Concatenated CPM-OFDMA Schemes for Aeronautical Telemetry. Fort Belvoir, VA: Defense Technical Information Center, kwiecień 2011. http://dx.doi.org/10.21236/ada543383.

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Zilberman, David, Amir Heiman i Yanhong Jin. Use of Branding and Sampling in Agricultural Fresh Produce. United States Department of Agriculture, lipiec 2013. http://dx.doi.org/10.32747/2013.7697116.bard.

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The original proposal has three main objectives: a conceptual framework on willingness to pay (WTP) for fruits and vegetables, the introduction of branding and sampling in fresh food, and empirical applications to the United States and Israel. We modified our research plan over time based on availability of data and emergence of new problems. We expanded the range of products to include poultry and the range of techniques to use real experiments as well as more traditional surveys. We expanded the range of problems to understand attitudes toward genetically modified (GM) food. There is a growing interest in introduction of marketing tools like demonstration sampling, money-back guarantees, labeling, and brands in agriculture. These marketing tools are important for enhancing demand for agricultural products and food safety. However, the methodology needed to assess the effectiveness of these tools and understand their performance in different agricultural sectors is limited. Our analysis demonstrated the importance of brands as a marketing tool in agriculture. In particular, we showed conceptually that strong brands can be substitutes for other marketing tools like sampling or demonstration. We were able to conduct real experiments for the demand for safe chicken and show that consumers are willing to pay significantly more for products branded as more safe. Yet, using experiments in Israel and the United States, we found that WTP for brands of fresh fruits and vegetables is smaller than in other product categories. Warning labels are a sort of negative branding. The GM-free labeling is particularly important since it serves as a trade barrier to U.S. crops exports. Our analysis of acceptance of GM products found that WTP for GM products in Israel and the United States depends on framing of information about the impact ofGM and the quantity of information disclosed. Finally, in analyzing the evolution of support for Proposition 37 that aimed to introduce mandatory labeling of GM in California, we found that support for mandatory labeling ofGM products is broad as long as it is not perceived to be costly. Our project demonstrates the feasibility of conducting real experiments to assess consumer demand in agriculture. When looking at interdisciplinary groups, one can design new products and assess the WTP for their characteristics. We also show that, while branding is a very strong marketing tool, its use in fresh fruit and vegetables is likely to be limited. However, brands can be important with processed food. Furthermore, we have proven that, while some consumers strongly object to GM products, most consumers in the United States and Israel would be willing to buy them for a discount, and some would pay extra if they are associated with improved characteristics. Finally, we expanded the notion of warning labels to calorie information and showed that the response to calorie information depends on gender, education, and how the information is presented.
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