RESEARCH PAPERS

ofdm research papers 2013


Orthogonal frequency-division multiplexing

PERFORMANCE ANALYSIS OF DWT-OFDM AND FFT-OFDM SYSTEMS
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Fourier Transforms (FFT) and Discrete Wavelet Transform (DWT) are analyzed in this paper. The performance of DWT-OFDM is assessed by various parameters such as BER, eye diagram and constellation diagram. BER is the ratio of the no. of bits with error to the total 

Performance Evaluation of Coded Adaptive OFDM System Over AWGN Channel
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ABSTRACT Adaptive OFDM (AOFDM) is the important approach to fourth generation of mobile communication. Adaptive modulating scheme is employed according to channel fading condition for improving the performance of OFDM. This gives improved data rate, spectral 

Iterative Receiver Processing for OFDM Modulated Physical-Layer Network Coding in Underwater Acoustic Channels.
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ABSTRACT Physical-layer network coding (PLNC) allows two remote terminals to exchange information in two time slots via a half-duplex relay. In this paper, we consider PLNC in underwater acoustic (UWA) two-way relay networks, with particular attention on the 

Comparative Study of Different Application of OFDM in FPGA Implementation
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ABSTRACT FPGA provides cost effective solutions to most of the circuits. OFDM is a technique which uses multi-carriers for the modulation in which each sub-carrier can be modulated separately. Due to this multiple carriers share the data among themselves. Due to OFDM 

A Synchronization Algorithm for Expanded Time and Frequency OFDM System
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ABSTRACT In this paper, we gave a brief discussion of the expanded time and frequency OFDM (ETF-OFDM) system and its traditional synchronization method (the Schmidl's method). And then we present a rapid frame and symbol synchronization algorithm in this 

Blind Maximum-likelihood Frequency Offset Estimation for Coherent Fast OFDM Receivers
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ABSTRACT We propose blind maximum-likelihood carrier frequency offset (CFO) estimation for coherent fast OFDM receivers. Simulation results show that the estimation algorithm can greatly enhance the CFO tolerance, and is insensitive to chromatic dispersion.

Peak-to-Average Power Ratio and Illumination-to-Communication Efficiency Considerations in Visible Light OFDM Systems
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ABSTRACT Visible light communication (VLC) systems can provide illumination and communication simultaneously via light emitting diodes (LEDs). Orthogonal frequency division multiplexing (OFDM) waveforms transmitted in a VLC system will have high peak- 

Preamble Based Timing Synchronization for OFDM Receivers
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ABSTRACT The fast synchronization is an essential function block for the packet based OFDM communication system. In general the synchronization should be completed within a limited period of time where the preamble or training sequence is normally assigned. One of the 

Linear Programming Algorithm for Expanded Time and Frequency OFDM System
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ABSTRACT In this paper, we present a linear programming algorithm for ETF-OFDM system to exploit the multi-user diversity present when communicating to multiple users. Utilizing the received channel characteristics as the adaptation criteria, we allocate subcarriers to 

Parameter Optimization of Automatic Gain Control for Improved Performance in OFDMSystems
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ABSTRACT In the OFDM systems for high data rate and burst data traffic networks, the fast convergence of the signal level is required in the short period of time at the input of the analog-to-digital convertor (ADC). This operation should be carried out at the header part 

Data Puncturing in OFDM Channel: A Multicarrier Stego
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ABSTRACT The prospects of the next generation wireless broadband applications will be enhanced by the features like improved Signal to Noise Ratio (SNR) and variable higher data rates. The Orthogonal Frequency Division Multiplexing (OFDM) system offers better 

Performance Analysis of ST, SF and STF in MIMO-OFDM Technique
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ABSTRACT In this paper with the advent of next generation (4G) broadband wireless communications, the combination of multiple-input multiple-output (MIMO) wireless technology with orthogonal frequency division multiplexing (OFDM) has been recognized 

Dual Turbo MIMO-OFDM Channel Estimation Based on Puncher Technique via UWA Channels
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ABSTRACT In this study, various techniques of UWA (Underwater Acoustic, UWA) channel estimation for underwater MIMO-OFDM system are studied. Dual turbo channel estimation algorithm based on channel puncture technique is proposed. In order to judge the criteria 

Power allocation approaches for combined positioning and communications OFDM systems
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ABSTRACT The design of pilot and data power allocations for multicarrier OFDM signals is a key aspect in the development of combined positioning and high-data-rate communications systems. Previous work has investigated the capacity-maximizing pilot and data power 

PAPR Reduction in OFDM systems using Quasi Cyclic LDPC Codes
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ABSTRACT Orthogonal Frequency Division l\/lultipleicing (OFDl\/T) is a multi carrier modulation technique where the revolution of 4G wireless communication is focused towards OFDM systems. The major drawback of OFDM system is high Peak to average 

Reducing the PAPR of OFDM Systems by Random Variable Transformation
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Peak power reduction techniques in orthogonal frequency division multiplexing (OFDM) has been an important subject for many researchers for over 20 years. In this letter, we propose a side-information-free technique that is based on the concept of random variable (RV) 

Joint Symbol Synchronization and Dispersion Estimation in 16QAM Optical Fast OFDM
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ABSTRACT We show that joint symbol synchronization and channel estimation can be realized using single symbol with negligible penalty in 16QAM optical F-OFDM. This facilitates the application of F-OFDM for burst-mode transceivers in optical packet networks.

Performance Evaluation For Detection Of White Spaces In Cognitive-Ofdm Based Wireless Communications Networks
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ABSTRACT The radio electromagnetic spectrum is limited source for many wireless communication devices. many studies on wireless communication show that a large portion of our radio electromagnetic spectrum remains vacant all time. How this radio 

Quadrature amplitude modulation: From basics to adaptive trellis-coded, turbo-equalised and space-time coded OFDM, CDMA and MC-CDMA systems
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An important accomplishment of information theory is the determination of the channel capacity, C, which quantifies the maximum achievable transmission rate, C*, of a system communicating over a bandlimited channel, while maintaining an arbitrarily low 

On channel estimation in OFDM systems
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ABSTRACT The use of multi-amplitude signaling schemes in wireless OFDM systems requires the tracking of the fading radio channel. This paper addresses channel estimation based on time-domain channel statistics. Using a general model for a slowly fading channel, we 

Coherent optical OFDM: theory and design
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ABSTRACT Coherent optical OFDM (CO-OFDM) has recently been proposed and the proof-of- concept transmission experiments have shown its extreme robustness against chromatic dispersion and polarization mode dispersion. In this paper, we first review the theoretical 

Active interference cancellation technique for MB-OFDM cognitive radio
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ABSTRACT Ultra Wideband transmit power (in-band) is regulated to be-41.25 dBm/MHz (in the United States), but in the future, it may be flexibly relaxed subject to the cognitive- radio spectrum policy. However, in close proximity of a protected radio service, 

Channel estimation for wireless OFDM systems
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ABSTRACT Orthogonal frequency division multiplexing (OFDM) is a special case of multi- carrier transmission and it can accommodate high data rate requirement of multimedia based wireless systems. Since channel estimation is an integral part of OFDM systems, it 

Theoretical and experimental study on PMD-supported transmission using polarization diversity in coherent optical OFDM systems
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ABSTRACT In this paper, we conduct theoretical and experimental study on the PMD- supported transmission with coherent optical orthogonal frequency-division multiplexing (CO-OFDM). We first present the model for the optical fiber communication channel in the 

A comparative study of pilot-based channel estimators for wireless OFDM
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This report deals with pilot-based channel estimation in wireless OFDM systems. We assume that the receiver is able to use all transmitted pilots, which is the case in broadcasting and in the downlink of a multiuser system. Four estimators (of which two 

Calculation of power limit due to fiber nonlinearity in optical OFDM systems
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ABSTRACT We develop a simple formula for estimating the effect of Four-Wave Mixing (FWM) on received signal quality in coherent optical systems using Orthogonal Frequency Division Multiplexing (OFDM) for dispersion compensation. This shows the nonlinear limit is 

On cyclic delay diversity in OFDM based transmission schemes
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ABSTRACT Cyclic Delay Diversity (CDD) is a simple ap-proach to introduce spatial diversity to an Orthogonal Frequency Division Multiplexing (OFDM) based transmission scheme that itself has no built-in diversity. It also can be regarded as a Space-Time Code (STC). But in 

Channel estimation in OFDM systems
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OFDM is becoming widely applied in wireless communications systems due to its high rate transmission capability with high bandwidth efficiency and its robustness with regard to multi- path fading and delay . It has been used in digital audio broadcasting (DAB) systems, 

The principles of OFDM
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By Louis Litwin and Michael Pugel 32 www. rfdesign. com January 2001 viewed from the standpoint of stochastic processes. If two random processes are uncorrelated, then they are orthogonal. Given the random nature of signals in a communications system, this 

WDM extended reach passive optical networks using OFDM-QAM
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ABSTRACT In order to reduce the cost for delivering future broadband services, network operators are inclined to simplify the network architectures by integrating the metro and access networks into a single system. Hence, extended reach passive optical networks ( 

All optical discrete Fourier transform processor for 100 Gbps OFDM transmission
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ABSTRACT Optical orthogonal frequency division multiplex (OFDM) symbol generation by all- optical discrete Fourier transform (DFT) is proposed and investigated for 100-Gbps transmission performance. We discuss a design example for a 4x25Gbps OFDM 

The suitability of OFDM as a modulation technique for wireless telecommunications, with a CDMA comparison.
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ABSTRACT This thesis investigates the effectiveness of Orthogonal Frequency Division Multiplexing (OFDM) as a modulation technique for wireless radio applications. The main aim was to assess the suitability of OFDM as a modulation technique for a fixed wireless 

Efficient subcarrier allocation for multiple access in OFDM systems
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ABSTRACT –In this paper we propose a computationally efficient subcarrier allocation algorithm for a multiuser OFDM system suited for downlink and uplink transmission. The algorithm considers user-individual bitrate and power constraints and allocates to each user the 

Intercarrier interference due to phase noise in OFDM-estimation and suppression
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ABSTRACT In this paper we provide an analysis of the inter-carrier interference (ICI) due to phase noise in OFDM systems and present an algorithm for its suppression. We examine the general case where phase noise can take any values, thus the small phase noise model 

Amplified-spontaneous noise limit of optical OFDM lightwave systems
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ABSTRACT Optical Orthogonal Frequency Division Multiplexing (O-OFDM) systems use electronic digital computation to provide dispersion compensation that can be rapidly adapted to changes in the optical link or optical network. Recent demonstrations have 

Adaptive coding and modulation in OFDM systems using BICM and rate-compatible punctured codes
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ABSTRACT Within the EU FP6 Integrated Project WINNER, adaptive transmission in a TDMA/OFDMA system is investigated as a key technology for boosting the spectral efficiency of a new radio interface for 4G systems. Adaptive allocation and linkadaptation of 

Optical performance monitoring in coherent optical OFDM systems
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ABSTRACT Optical performance monitoring is an indispensable feature for optical systems and networks. In this paper, we propose the concept of optical performance monitoring through channel estimation by receiver signal processing. We show that in coherent-optical- 

request paper Generation, transmission and coherent detection of 11.2 Tb/s (112×100Gb/s) single source optical OFDM superchannel

Generation, transmission and coherent detection of 11.2 Tb/s (112× 100Gb/s) single source optical OFDM superchannel
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Abstract: A novel scheme to generate coherent 112 optical sub-carriers with subcarrier spacing of 25GHz is proposed and experimentally demonstrated. By using these coherent optical subcarriers, we have successfully generated 10-Tbit/s (112x100Gbit/s) single


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