Showing 1-25 of 54,188 resultsfor "Index Terms":Orthogonal Division Multiplexing (OFDM)
"Index Terms":Orthogonal Division Multiplexing (OFDM)
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A novel minimum output variance estimator for carrier frequency offset in OFDM systems
Tsinghua Science and Technology
Cited by: Papers (2)
In orthogonal frequency-division multiplexing (OFDM) systems, the carrier frequency offset (CFO) destroys the orthogonality among subcarriers which degrades system performance. Various CFO estimation methods have been developed to compensate for the CFO at the receiver. This paper describes a novel minimum output variance method for OFDM systems with CFO in additive white Gaussian nois...Show More
Particle-based iterative blind receiver for orthogonal frequency-division multiplexing with frequency offset
Orthogonal frequency-division multiplexing (OFDM) systems are sensitive to carrier frequency offset (CFO) which introduces intercarrier interference and significantly degrades system performance. This paper describes an iterative blind receiver consisting of a sequential Monte Carlo detector, a CFO estimator, and a compensator to reduce intercarrier interference. The framework is of low comp...Show More
In this letter, we analyze the transmitter design for coherent optical orthogonal frequency-division multiplexing (CO-OFDM) employing predistortion. Digital clipping and digital predistortion processes are introduced to the radio frequency OFDM transmitter to compensate the nonlinearity effect introduced by the optical in-phase/quadrature modulator. We first provide a detailed description of signa...Show More
Transmission of Wavelength-Division-Multiplexed Channels With Coherent Optical OFDM
IEEE Photonics Technology Letters
Cited by: Papers (6)
Transmission performance for wavelength-division-multiplexed (WDM) systems with coherent optical orthogonal frequency-division multiplexing is simulated including the fiber nonlinearity effect. The simulation shows that the system Q of the WDM channels at 10 Gb/s is over 13.0 dB for a transmission up to 4800 km of standard single-mode fiber without dispersion compensationShow More
Maximum-Likelihood-Based Performance Enhancement of Clipped and Filtered OFDM Systems With Clipping Noise Cancellation
Clipping and filtering (CAF) technique is known as a simple and effective approach that reduces the peak-to-average power ratio (PAPR) of orthogonal frequency-division multiplexing (OFDM) signals at the cost of increasing in-band distortion. Clipping noise cancelation (CNC) can compensate for the performance degradation due to the in-band distortion caused by CAF, especially when the number ...Show More
Space-Frequency Conjugate Two-Path Transmission for Precoded OFDM Systems
This brief presents space-frequency (SF) conjugate two-path transmission orthogonal frequency division multiplexing (OFDM) systems with precoders to combat inter-carrier interference in mobile fading channels. Initially, an SF architecture is developed to form an SF-OFDM system. Second, a conjugate cancellation two-path transmission scheme is integrated with the SF-OFDM system to...Show More
Orthogonal Chirp Division Multiplexing in Visible Light Communication: A Performance Comparison with OFDM-based Systems
Augusto C. F. Peterle;Wesley Costa;Higor Camporez;Marcelo Segatto;Helder Rocha;Jair A. L. Silva
2021 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC)
Year: 2021 | Conference Paper |
Cited by: Papers (3)
Performance comparisons between visible light communication (VLC) systems based on orthogonal chirp division multiplexing (OCDM) and orthogonal frequency division multiplexing (OFDM) are presented in this paper. Unlike most of the related publications, in this work we compared OCDM and OFDM based VLC systems with the same equalization process, i.e., employing one tap equalizer in both ...Show More
Pulsed-OFDM Modulation for Ultrawideband Communications
In this paper, we describe a novel approach for reducing the power consumption and complexity of a multiband orthogonal frequency-division multiplexing (MB-OFDM) ultrawideband (UWB) system by applying ideas from pulsed UWB systems. The approach is quite general and applicable to many other systems. Unlike the MB-OFDM system, the enhancement that we propose uses pulses with duty cycles ...Show More
An Experimental Proof of Concept for OFDM-based ISAC System Utilizing Stepped-Carrier and TDM MIMO scheme
2024 IEEE 25th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC)
Year: 2024 | Conference Paper |
The problem with orthogonal frequency-division multiplexing (OFDM)-based integrated sensing and communication (ISAC) system is that the bandwidth required for high range resolution cannot be obtained. This problem can be overcome by using a stepped-carrier method, where the carrier frequency of each OFDM signal increases linearly to achieve wide overall RF bandwidth. In this article, f...Show More
Blind symbol-timing and frequency-offset estimation in OFDM systems with real data symbols
In this letter, the problem of blind symbol-timing and frequency-offset estimation in orthogonal frequency-division multiplexing (OFDM) systems with real data symbols is considered. Maximum-likelihood (ML) estimators for the parameters of interest have been derived by modeling the OFDM signal as a proper complex Gaussian random process. However, when data symbols belong to a real const...Show More
LDPC-Coded OFDM Transmission Over Graded-Index Plastic Optical Fiber Links
IEEE Photonics Technology Letters
Cited by: Papers (13)
The possibility of 10-Gb/s transmission over graded-index plastic optical fiber (GI-POF) using the orthogonal frequency-division multiplexing (OFDM) and iteratively decodable codes is demonstrated by simulations. Several classes of low-density parity-check (LDPC) codes suitable for use in LDPC-coded OFDM transmission over GI-POF are presented as well. Several power efficient OFDM...Show More
Experimental Demonstration and Numerical Simulation of 107-Gb/s High Spectral Efficiency Coherent Optical OFDM
Orthogonal frequency-division multiplexing (OFDM) is a multicarrier modulation format in which the data are transmitted with a set of orthogonal subcarriers. Recently, this modulation format has been actively explored in the field of optical communications to take advantages of its high spectral efficiency and resilience to chromatic and polarization dispersion. However, to realize the optic...Show More
Comments on "Semi-Blind Channel Estimation and Equalization for MIMO Space - Time Coded OFDM
For original paper see ibid., vol.53, no.2, p.363-374, Feb. 2006. A semiblind channel estimation scheme of the multiple-input-multiple-output space-time coded orthogonal frequency-division multiplexing system was proposed in the aforementioned paper for either real or complex with symmetric signals. We point out that this scheme cannot work correctly for complex signal scenario.Show More
A Novel Two-Step Channel-Prediction Technique for Supporting Adaptive Transmission in OFDM/FDD System
This paper introduces a novel channel-prediction technique for an orthogonal frequency-division multiplexing (OFDM)/frequency-division duplex (FDD) system to support an adaptive-modulation and coding (AMC) scheme over a rapidly time-varying multipath fading channel. Most channel-prediction techniques assume that there is no channel variation in the predefined time duration, e.g. the slot. As...Show More
We show the first experiment of bit and power loading for coherent optical orthogonal frequency-division-multiplexing (CO-OFDM) systems. The data rate of CO-OFDM systems can be dynamically adjusted according to the channel condition. The system performance can be further improved through optimal power loading into each modulation band.Show More
Precoded Multiuser OFDM Transceiver in Timing Asynchronous Environment
The performance of a multiuser orthogonal frequency-division multiplexing (OFDM) transceiver, called the precoded multiuser OFDM (PMU-OFDM), with time asynchronous access is investigated in this paper. It is shown that multiaccess interference (MAI) due to time asynchronism is asymptotically zero as the number of parallel input symbols N becomes large in the PMU-OFDM system...Show More
All-optical OFDM baesd on arrayed grating waveguides in WDM systems
2011 International Conference on Electronics, Communications and Control (ICECC)
Year: 2011 | Conference Paper |
Cited by: Papers (2)
Recently, arrayed waveguide gratings (AWGs) is reported as IDFT/DFT circuits in all-optical orthogonal frequency-division multiplexing (OFDM) system for its potential in large subcarriers and simplified structure. In our paper, we combine the AWGs-based all-optical OFDM system with wavelength division multiplexing (WDM). This scheme is rather simplified than the others which can realiz...Show More
Transmission performance of adaptively modulated optical OFDM signals in multimode fiber links
A novel optical signal modulation concept of adaptively modulated optical orthogonal frequency-division multiplexing (AMOOFDM) is proposed and numerical simulations of the transmission performance of AMOOFDM signals are undertaken in unamplified multimode fiber (MMF)-based links using directly modulated distributed feedback lasers (DMLs). It is shown that 28 Gb/s intensity modulation and direct-de...Show More
Support vector machines for robust channel estimation in OFDM
M.J.F.-G. Garcia;J.L. Rojo-Alvarez;F. Alonso-Atienza;M. Martinez-Ramon
IEEE Signal Processing Letters
Cited by: Papers (39)
A new support vector machine (SVM) algorithm for coherent robust demodulation in orthogonal frequency-division multiplexing (OFDM) systems is proposed. We present a complex regression SVM formulation specifically adapted to a pilots-based OFDM signal. This novel proposal provides a simpler scheme than an SVM classification method. The feasibility of our approach is substantiated by com...Show More
QAM Symbol Error Rate in OFDM Systems Over Frequency-Selective Fast Ricean-Fading Channels
For digital data transmission using an orthogonal frequency-division multiplexing (OFDM) over fading channels, the interchannel- interference (ICI) term caused by the Doppler spread is correlated with the desired signal term. Nonetheless, many researchers have assumed the ICI term to be uncorrelated with the desired signal term. In this paper, we present the symbol-error-rate (SER) performan...Show More
Improving the Nonlinear Tolerance of Polarization-Division-Multiplexed CO-OFDM in Long-Haul Fiber Transmission
We present digital signal processing techniques and algorithms for improving the tolerance of polarization-division multiplexed (PDM) coherent optical orthogonal frequency-division multiplexing (CO-OFDM) to fiber nonlinear effects, in both single-channel and wavelength-division multiplexed (WDM) transmission. For single-channel transmission, we discuss a self-phase modulation (SPM) compensat...Show More
Analysis of RF-Pilot-Based Phase Noise Compensation for Coherent Optical OFDM Systems
In coherent optical long-haul transmission systems, orthogonal frequency-division multiplexing represents a promising modulation format. However, due to long symbol length, laser phase noise can be a major impairment. In this manuscript, the RF-pilot-based phase noise compensation scheme is analyzed and compared to conventional common-phase error compensation. It has been shown that the RF-pilot-b...Show More
A novel non-data-aided symbol timing recovery technique for OFDM systems
A new highly efficient non-data-aided technique to recover symbol timing of orthogonal frequency-division multiplexing systems is proposed. The algorithm in the proposed work exploits the interference that results due to the loss of orthogonality between subcarriers, where the second-order statistics of the resulting interference is proportional to the offset from the optimum sampling point. The p...Show More
Noniterative Joint Frequency Offset and Channel Estimation for MIMO OFDM Systems Using Cascaded Orthogonal Pilots
In this paper, we reconsider the issues of frequency offset and channel estimation in multiple-input-multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) systems. We first design “cascaded orthogonal” pilot symbols and adopt the properties of Fourier transform and Hadamard product to deliver a closed-form estimate of frequency offset; meanwhile, another closed-form estimate...Show More
MAP-Based Channel Estimation for MIMO–OFDM Over Fast Rayleigh Fading Channels
This paper presents a channel estimation scheme for multiple-input multiple-output with orthogonal frequency-division multiplexing (MIMO-OFDM) in fast varying Rayleigh channels. To handle rapid variation of channels within a transmission block, we propose a novel maximum a posteriori probability-based channel estimation scheme using pilot symbols. With the estimate of the channel matrix for ...Show More
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