scholarly journals IMPLEMENTATION AND COMPARISON OF WAVELET TRANSFORM AND FOURIER TRANSFORM IN WI-MAX OFDM SYSTEM

2014 ◽  
pp. 280-283
Author(s):  
P. MAHESH KUMAR ◽  
K. SARADA
Keyword(s):  
Wavelet Transform ◽  
Error Rates ◽  
Cyclic Prefix ◽  
Spectrum Efficiency ◽  
Discrete Wavelet ◽  
Noise Power ◽  
Time Varying ◽  
Ofdm System ◽  
Guard Interval ◽  
International Telecommunications

WIMAX wireless communication is based on ofdm technology which enables going towards 4G Based on IEEE 802.16d-2004. But the reliability of ofdm is limited with the problems of time varying nature of the channel. This can reduced by adding cyclic prefix or guard interval between each block of data symbols. This guard interval minimizes the spectral efficiency in ofdm system. Recently, it was proved that discrete wavelet transform in ofdm system will reduce the isi Inter carrier interference, which is produced by loss of ortho-gonality between carriers and also provides more spectrum efficiency. It is found that proposed wavelet design achieves much lower bit error rates, Increases signal to noise power ratio (SNR), and can be used as an alternative to the Conventional OFDM WIMAX. The proposed OFDM system was modeled tested, and its Performance was found under different International Telecommunications Union (ITU Channel models.

scholarly journals BER Analysis of SWT Based OFDM ON LTE

2020 ◽  
Vol 5 (2) ◽  
pp. 82-87
Author(s):  
T. Nagarjuna ◽  
K. Nehru ◽  
G. Nagendra Prasad ◽  
Hema Chowdary
Keyword(s):  
Wavelet Transform ◽  
Bit Error Rate ◽  
Real World ◽  
Channel Model ◽  
Error Rates ◽  
Cyclic Prefix ◽  
Spectrum Efficiency ◽  
Rate Performance ◽  
Awgn Channel ◽  
Modulation Techniques

We proposed to use singular wavelet transform (SWT) in OFDM based LTE because the SWT based system does not require a cyclic prefix, so spectrum efficiency is increased. SWT is used to analyze signals by the coefficients of SWT in both time and frequency domain. In order to investigate the bit error rate performance a practical channel model is required.  Many channel models are proposed to mimic a real world scenario. Out of which Stanford university interim (SUI) channel provides best results so we replaced AWGN channel with SUI channel. We investigated the performance of bit error rates of SWT based OFDM in LTE for different modulation techniques such as QPSK, 64 QAM, 128 QAM under SUI 3 Channel model using SWT based haar and db2 transform. BER is reduced by 2 times when compared to the existing system.

scholarly journals Spectral Efficiency Enhancement Through Wavelet Transform Filter Bank for Future Mobile Communications

2019 ◽  
Vol 8 (9S2) ◽  
pp. 828-829
Keyword(s):  
Wavelet Transform ◽  
Mobile Communications ◽  
Spectral Efficiency ◽  
Time Synchronization ◽  
Transmission Rate ◽  
Multipath Fading ◽  
Error Rates ◽  
Discrete Wavelet ◽  
Main Requirement ◽  
Low Sensitivity

In the 5th generation of wireless communications for multiple apps, such as sports, video etc, the large transmission rate of information is the main requirement. To satisfy the high information rates, bandwidth can be increased by using greater frequency bands that is not feasible owing to the restricted frequency spectrum accessibility and the limitation placed on accessible spectrums by Standard. A further way is to effectively use the existing spectrum. OFDM overrides all multiplexing methods in the last century because with Cyclic Prefix (CP) and enhanced Bit Error Rates (BER) the system improves intersymbolic interference (ISI). It offers low sensitivity owing to the intercarrier orthogonality to time synchronization. Bandwidth is lost by CP, in addition to all of these benefits. The lack of orthogonality between pilots that interfere (ICI) is also due to the multipath fading. Discrete Wavelet Transform is used to extract a bandwidth and spectral efficiency improvement and remove CP in turn. Transforming Wavelet (WT) is less sensitive to multipath distortion., so that ICI improves.. We present FBMC's unifying structure, discussion and efficiency assessment in this paper.

scholarly journals Improving MIMO-OFDM Performance with Convolutional Coding and Discrete Wavelet Transform

2020 ◽  
pp. 299-305
Author(s):  
Saad S. Hreshee ◽  
◽  
Qais K. Al-Gayem
Keyword(s):  
Wavelet Transform ◽  
Discrete Wavelet Transform ◽  
Fading Channel ◽  
Orthogonal Frequency Division Multiplexing ◽  
Rayleigh Fading ◽  
Rician Fading ◽  
Discrete Wavelet ◽  
Ofdm System ◽  
Convolutional Coding ◽  
Mimo Ofdm

This paper presents a new way to improve the performance of MIMO-OFDM (multiple input multiple output - orthogonal frequency division multiplexing) by reducing the Bit Error Rate (BER) using both Convolutional Coding (CC) and discrete wavelet transform (DWT). In this Paper, OFDM system was simulated and studied with three models, SISO-OFDM, MISO-OFDM and MIMO-OFDM. The final system (MIMO-OFDM) has been improved by using CC at a coding rate 1/2 and using a DWT instead of FFT and then using both CC and DWT. The communication channels used in the study are Rician and Rayleigh fading channels and the modulation technique is Binary Phase-Shift Keying (BPSK) with 64 number of carrier frequencies. The results showed that the use of both convolutional coding and discrete wavelet transform in the MIMO-OFDM system reduces the bit energy to the intensity of noise energy (Eb/N0) by 3.4 dB as the Rayleigh fading channel is used and 4.6 dB as the Rician fading channel is used when BER=10-3. The results were obtained by modeling in the MATLAB program.

A wavelet transform and substructure algorithm for tracking the abrupt stiffness degradation of shear structure

2018 ◽  
Vol 22 (5) ◽  
pp. 1136-1148 ◽  
Author(s):  
Chao Wang ◽  
Demi Ai ◽  
Wei-Xin Ren
Keyword(s):  
Wavelet Transform ◽  
Degrees Of Freedom ◽  
Least Square Method ◽  
Least Square ◽  
Stiffness Degradation ◽  
Discrete Wavelet ◽  
Time Varying ◽  
Engineering Structures ◽  
Shear Structure ◽  
Stiffness And Damping

Time-varying parameter identification is an important research topic for structural health monitoring, performance evaluation, damage diagnosis, and maintenance. Practical civil engineering structures usually contain multiple degrees of freedom; however, damage often locally occurs. In this study, a discrete wavelet transform and substructure algorithm is presented for tracking the abrupt stiffness degradation of shear structures. A substructure model is built by the extraction of the local structure which may contain damaged region. Time-varying stiffness and damping are expanded into multi-scales using discrete wavelet analysis. An optimization method based on Akaike information criterion is introduced to select the decomposition scale. The expanded scale coefficients are evaluated using least square method, then the original time-varying stiffness or damping parameter is identified by reconstructing from the scale coefficients. To validate the proposed method, a numerical example of seven-story shear structure with time-varying stiffness and damping is proposed. Experiment for a three-story shear-type structure with abrupt stiffness degradation is also tested in the laboratory. Both numerical and experimental results indicate that the proposed method can effectively identify the abrupt degradation of stiffness parameter with a satisfactory accuracy.

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