scholarly journals A Radon Slantlet Transforms Based OFDM System Design and Performance Simulation under Different Channel Conditions

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Abbas Hasan Kattoush
Keyword(s):  
Radon Transform ◽  
Spectral Efficiency ◽  
Fading Channel ◽  
Orthogonal Frequency Division Multiplexing ◽  
Additive White Gaussian Noise ◽  
Mapping Technique ◽  
Intercarrier Interference ◽  
Ofdm Systems ◽  
Ofdm System ◽  
Channel Parameters

Due to its good orthogonality, slantlet transform (SLT) is used in orthogonal frequency division multiplexing (OFDM) systems to reduce intersymbol interference (ISI) and intercarrier interference (ICI). This eliminates the need for cyclic prefix (CP) and increases the spectral efficiency of the design. Finite Radon transform (FRAT) mapper has the ability to increase orthogonality of subcarriers, is nonsensitive to channel parameters variations, and has a small constellation energy compared with conventional fast-Fourier-transform- (FFT-) based OFDM. It is also able to work as a good interleaver, which significantly reduces the bit error rate (BER). In this paper both FRAT mapping technique and SLT modulator are implemented in a new design of an OFDM system. The new structure was tested and compared with conventional FFT-based OFDM, Radon transform-based OFDM, and SLT-based OFDM for additive white Gaussian noise (AWGN) channel, flat fading channel (FFC), and multipath selective fading channel (SFC). Simulation tests were generated for different channel parameters values. The obtained results showed that the proposed system has increased the spectral efficiency, reduced ISI and ICI, and improved BER performance compared with other systems.

scholarly journals INTER CARRIER INTERFERENCE AND SIGNAL TO INTERFERENCE RATIO OF VARIOUS PULSE SHAPING FUNCTIONS USED IN OFDM SYSTEM WITH CARRIER FREQUENCY OFFSET

2012 ◽  
pp. 68-71
Author(s):  
SHANKAR AENAGANDULA ◽  
ASHOK KUMAR ◽  
SRINIVAS K ◽  
MONIKA NANDA
Keyword(s):  
Carrier Frequency ◽  
Orthogonal Frequency Division Multiplexing ◽  
Pulse Shaping ◽  
Carrier Frequency Offset ◽  
Signal To Noise Ratio ◽  
Frequency Offset ◽  
Performance Comparison ◽  
Intercarrier Interference ◽  
Ofdm Systems ◽  
Ofdm System

Orthogonal Frequency Division Multiplexing (OFDM) is the important modulation of choice for fourthgeneration broadband multimedia wireless systems. This paper is focused on the problem of reducing the intercarrierinterference (ICI) and signal to noise ratio in the transmission over OFDM using various pulse shaping methods. Here we have performed a detailed performance comparison of various pulse shaping functions used in OFDM System with Carrier Frequency Offset. They appear to be suitable for transmission in OFDM systems with carrier frequency offset. The results obtained by analysis show that the performance improvement over conventional pulse shapes, are significant for reducing average intercarrier-interference (ICI) power and increased ratio of average signal power to average ICI power (SIR).

scholarly journals BER PERFORMANCE ANALYSIS OF 4QAM/OFDM OVER DIFFERENT SCENARIOS OF LAPLACE FADING CHANNEL.

2021 ◽  
Vol 25 (Special) ◽  
pp. 1-26-1-33
Author(s):  
Hassan F. Mohammed ◽  
◽  
Ghanim A. Al-Rubaye ◽  
Keyword(s):  
Fading Channels ◽  
Fading Channel ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Speed ◽  
Additive White Gaussian Noise ◽  
Multipath Fading ◽  
Local Area ◽  
Ofdm System ◽  
Multicarrier Transmission ◽  
Simulation Results

Multicarrier transmission, also known as (OFDM) Orthogonal Frequency Division multiplexing, in wireless communications, it has been proven to be an essential technique for countering multipath fading. It has been used successfully for HF radio applications and has been selected as the interface for digital audio transmission, digital terrestrial TV broadcasting, and high-speed wireless local area networks in Europe. In this paper, we suggested a new design for modeling multipath fading channels, such as the Laplace fading channel, in order to discover new simulation results and effects. Furthermore, the variance of the Laplace fading channel has been computed and the new Bit Error Rate (BER) derivation is established, and the performance of (M-QAM), M-ary Quadrature Amplitude Modulation (with M=4 over OFDM system under Laplace fading channels in Additive White Gaussian Noise (AWGN) is discussed and compared to the conventional M-QAM/OFDM system Rayleigh fading channel in AWGN. All the simulation results are examined using the optimum signal detection based on the Euclidean distance and evaluated using Monte-Carlo simulation.

Compensation of Phase Noise Effects for IEEE 802.16e OFDMA Systems

2011 ◽  
Vol 204-210 ◽  
pp. 1330-1335
Author(s):  
Chien Sheng Chen ◽  
Yung Chuan Lin ◽  
He Nian Shou ◽  
Chi Tien Sun
Keyword(s):  
Phase Noise ◽  
Fading Channel ◽  
Orthogonal Frequency Division Multiplexing ◽  
Phase Error ◽  
Delay Spread ◽  
Ofdm Systems ◽  
Ofdm System ◽  
Ieee 802.16E ◽  
Noise Effects ◽  
Channel One

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.

scholarly journals PAPR Reduction of OFDM System with Biorthoganoal Wavelet Transforms

2021 ◽  
pp. 17-22
Author(s):  
Palle Jagadeeswara Rao and Dr. A S Srinivasa Rao
Keyword(s):  
Wavelet Transform ◽  
Wavelet Transforms ◽  
Orthogonal Frequency Division Multiplexing ◽  
Spectrum Efficiency ◽  
Frequency Division Multiplexing ◽  
Intercarrier Interference ◽  
Frequency Division ◽  
Ofdm Systems ◽  
Ofdm System ◽  
Available Bandwidth

Orthogonal Frequency Division Multiplexing (OFDM) and Multiple Input and Multiple Output (MIMO) are two main techniques employed in 4th Generation Long Term Evolution (LTE). In OFDM multiple carriers are used and it provides higher level of spectral efficiency as compared to Frequency Division Multiplexing (FDM). In OFDM because of loss of orthogonality between the subcarriers there is intercarrier interference (ICI) and intersymbol interference (ISI) and to overcome this problem use of cyclic prefixing (CP) is required, which uses 20% of available bandwidth. Wavelet based OFDM provides good orthogonality and with its use Bit Error Rate (BER) is improved. Wavelet based system does not require cyclic prefix, so spectrum efficiency is increased. It is proposed to use wavelet transform including biorthoganoal wavelet transform with OFDM systems. This approach will reduce PAPR in the OFDM system effectively. We will design this model with different modulation Techniques like QPSK and QAM and compare the BER results.

scholarly journals An Efficient DWT-DAPM Technique for PAPR Reduction in OFDM System

2020 ◽  
Vol 9 (3) ◽  
pp. 1691-1696 ◽  
Keyword(s):  
Amplitude Modulation ◽  
Fading Channel ◽  
Orthogonal Frequency Division Multiplexing ◽  
Average Power ◽  
Gaussian Model ◽  
Channel Noise ◽  
Discrete Wavelet ◽  
Ofdm System ◽  
Flat Fading ◽  
Frequency Selective

In this paper, Discrete Wavelet Transform (DWT) Orthogonal Frequency Division Multiplexing (OFDM) system is compared with Discrete Cosine Transform (DCT) and Discrete Fourier Transform (DFT) OFDM systems. The channel noise is modelled with A white Gaussian Model (AWGN), the fading is the impairment in the channel and modelled by Rayleigh fading which is frequency selective fading channel and flat fading channel. The comparisons of Peak to Average Power Ratio (PAPR) and Bit Error Rate (BER) are made using modulation techniques such as Differential Amplitude and Phase Modulation (DAPM), Quadrature Amplitude Modulation (QAM) and Pulse Amplitude Modulation (PAM). Simulation results shows that PAPR is 4.497 dB for DWT-DAPM combination, 4.684 dB for DWT-QAM combination and 6.211 dB for DWT- PAM combination at 10-3 Complementary Cumulative Distributive Function (CCDF).The performance Analysis with the combination of DFT, DCT with DAPM, QAM and PAM are also compared. The BER is 0.01816, 0.01806 at 20 dB SNR in frequency selective channel, flat fading channel for DWT-DAPM and for DWT- QAM, AWGN channel BER is 0.01765 at 20dB SNR.

scholarly journals Performance Enhancement of Coherent Optical OFDM System Using LMS Algorithm

2020 ◽  
Vol 1 ◽  
pp. 1-5
Author(s):  
Manisha Bharti
Keyword(s):  
Phase Noise ◽  
Bit Error Rate ◽  
Error Rate ◽  
Orthogonal Frequency Division Multiplexing ◽  
Performance Enhancement ◽  
Lms Algorithm ◽  
Frame Structure ◽  
Least Mean Square ◽  
Ofdm Systems ◽  
Ofdm System

Instability of the local oscillator causes phase noise – a phenomenon that is a disadvantage and is considered to be a major obstacle in the functioning of coherent optical orthogonal frequency division multiplexing (CO-OFDM) systems. An attempt has been made in this paper to reduce the effects of common phase errors generated by phase noise. In this paper, a least mean square (LMS) based algorithm is proposed for estimation of phase noise. Using this proposed algorithm, the major problem of phase ambiguity caused by cycle slip is avoided and the bit error rate is greatly improved. Further, there is no requirement for modifying the frame structure of OFDM using this algorithm. A CO-OFDM system with the 8-PSK technique is used to implement the algorithm concerned. Furthermore, the algorithm, using the 8-PSK modulation technique, is analyzed and compared with the existing QPSK technique and with other algorithms. The investigations reveal that 8-PSK outperforms existing LMS algorithms using other techniques and significantly reduces the bit error rate.

PERFORMANCE OF QAM-OFDM SYSTEM OVER RAYLEIGH FADING CHANNEL IN WEI BULL NOISE DISTRIBUTION

2021 ◽  
Vol 25 (Special) ◽  
pp. 1-157-1-166
Author(s):  
Nabaa I. Abed ◽  
◽  
Ghanim A.AL Rubaye ◽  
Keyword(s):  
Fading Channels ◽  
Communication Networks ◽  
Orthogonal Frequency Division Multiplexing ◽  
Rayleigh Fading ◽  
Additive White Gaussian Noise ◽  
Wireless Networking ◽  
Ofdm System ◽  
Exact Match ◽  
Communication Industry ◽  
Non Gaussian

The phenomenal increase in the usage of mobile devices and wireless networking tools in recent years has resulted in the communication industry needing higher data speeds for connections and bandwidth. As a result, multi-carrier modulation has been suggested as a reliable and effective method of transmitting data over difficult communication networks such as selective fading channels. Orthogonal Frequency Division Multiplexing (OFDM) is a highly effective multi-carrier technique that can meet users' high demands. Many studies have looked into this technique, mostly as a way to counteract fading and Additive White Gaussian Noise (AWGN). As a result, the performance evaluation of the QAM-OFDM system in the presence of multi-path Rayleigh fading in Weibull noise is examined in this article. Furthermore, bit error rate performance (BER) is computed using the optimal derivation of the real system contaminated by compound Gaussian and non-Gaussian (Weibull) noise distributions at the OFDM demodulator output. The derived result is an exact match to the simulated result over various scenarios introduced by the MATLAB software package.

Generalized Trapezoidal Companding Technique for PAPR Reduction in OFDM Systems

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
Saruti Gupta ◽  
Ashish Goel
Keyword(s):  
Bit Error Rate ◽  
Orthogonal Frequency Division Multiplexing ◽  
Average Power ◽  
Frequency Division ◽  
Performance Parameters ◽  
Ofdm Systems ◽  
Ofdm System ◽  
Ofdm Signal ◽  
Specific Degree ◽  
Ofdm Signals

Abstract The main drawback in the performance of the Orthogonal Frequency Division Multiplexing (OFDM) system is the higher Peak-to-Average Power Ratio (PAPR) of the OFDM signals at the transmitter side. Companding is a well-known technique useful for reducing PAPR in the OFDM signal. This paper proposes a new nonlinear companding scheme that transforms the magnitude of Rayleigh distributed OFDM signal of specific degree into trapezoidal distribution. Additional design parameter is used in the proposed companding scheme to make the companding function more flexible. In the designed OFDM system the companding function has more degree of freedom which improves the PAPR and bit error rate (BER) parameters of the designed system. It has been demonstrated that the designed companding scheme provides more flexibility to accomplish an optimum trade-off between the performance parameters PAPR and BER of the designed OFDM system.

scholarly journals Evaluation of Clipping and Filtering-Based PAPR Reduction in OFDM System

2017 ◽  
Vol 1 (2) ◽  
pp. 18
Author(s):  
N. M. A. E. D. Wirastuti ◽  
N. Pramaita ◽  
I M. A. Suyadnya ◽  
D. C. Khrisne
Keyword(s):  
Fourier Transform ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Speed ◽  
Average Power ◽  
Ofdm Systems ◽  
Ofdm System ◽  
Parallel Data ◽  
Serial Data ◽  
Filtering Technique ◽  
Clipping And Filtering

This paper investigates clipping and filtering techniques in reducing peak average power ratio (PAPR) of Orthogonal Frequency Division Multiplexing (OFDM) system. The concept of OFDM is to split a high speed serial data into parallel data at a lower speed, then the parallel data carried by mutually orthogonal subcarriers. The high of PAPR is one of disadvantages of OFDM system. The high PAPR can damages the form of OFDM and reduces its performance. The purpose of this study is to reduce PAPR using simulation. OFDM was simulated with and without clipping filtering then compared.  The methods used to reduce PAPR was clipping and filtering technique. Clipping and filtering technique operates by clipping the output of inverse Fourier transform that exceed the threshold. Graphics PAPR vs. CCDF was used to evaluate the performance of OFDM systems. PAPR for OFDM system using Fourier transform when CCDF = 10-3 is 11,2 dB, with classical clipping PAPR was 4,1 dB and PAPR 4,6 dB when with deep clipping.

An Improved Data-Aided Symbol Timing Algorithm for OFDM Systems

2011 ◽  
Vol 403-408 ◽  
pp. 1568-1571
Author(s):  
Xiao Yan Zhao
Keyword(s):  
Fading Channel ◽  
Orthogonal Frequency Division Multiplexing ◽  
Signal To Noise Ratio ◽  
Multipath Fading ◽  
Ofdm Systems ◽  
Multipath Fading Channel ◽  
Symbol Synchronization ◽  
Timing Errors ◽  
Symbol Timing ◽  
Training Symbol

Synchronization is very important to orthogonal frequency division multiplexing (OFDM) systems. Taking aim at the problem that the timing inaccuracy of the S&C method and the indistinct peak of the timing metric produced by Park method under the low signal-to-noise ratio (SNR) and fading channel, a new symbol synchronization algorithm based on the training symbol is proposed in this paper. The new algorithm exploits the training symbol proposed by S&C to correlate the received signal with the known training symbol again at the receiving end to identify the start point of the OFDM symbol. The result of the simulation shows that the proposed method’s timing metric is of the impulse-shaped peak under the condition of the lower SNR and multipath fading channel, and has smaller timing errors compared with the conventional method in terms of mean-square error (MSE) of the timing estimator.

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