BER Improvement in OFDM Systems Using Wavelet Transform Based on Kalman Filter

BER Improvement in OFDM Systems Using Wavelet Transform Based on Kalman Filter

Sajjan Singh (CGC Technical Campus, Jhanjeri, India)
Copyright: © 2020 |Pages: 23
DOI: 10.4018/978-1-7998-1152-7.ch005


Orthogonal frequency division multiplexing (OFDM) is an efficient method of data transmission for high speed communication systems over multipath fading channels. However, the peak-to-average power ratio (PAPR) is a major drawback of multicarrier transmission systems such as OFDM is the high sensitivity of frequency offset. The bit error rate analysis (BER) of discrete wavelet transform (DWT)-OFDM system is compared with conventional fast Fourier transform (FFT)-OFDMA system in order to ensure that wavelet transform based OFDMA transmission gives better improvement to combat ICI than FFT-based OFDMA transmission and hence improvement in BER. Wavelet transform is applied together with OFDM technology in order to improve performance enhancement. In the proposed system, a Kalman filter has been used in order to improve BER by minimizing the effect of ICI and noise. The obtained results from the proposed system simulation showed acceptable BER performance at standard SNR.
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The FFT based systems are replaced by one of the wavelet transforms called the discrete wavelet transform (DWT). Since DWT based OFDM does not use cyclic prefix, so a better spectral control of channels can be achieved. Discrete wavelet transform employs a low pass filter (LPF) and a high pass filter (HPF) which operates as a quadrature mirror filters fulfilling perfect reconstruction and orthogonal properties. In order to transmit the modulated signal zero padding and vector transposing is done in DWT OFDM systems. The use of wavelet promises to reduce the inter symbol interference (ISI) and inter carrier interference (ICI). The wavelet transform offers a higher suppression of side lobes. First, gives the already existing self-cancellation scheme and adaptive modulation to decrease ICI in OFDM system have been explained. Kalman filter (KF) method, statistically estimate the frequency offset and correct the offset, using the estimated value at the receiver. It has been showed that using Kalman filter with DWT based OFDM systems; improvement in BER can be made Kalman filter has been discussed laterally. From discussion then observed that the proposed DWT-based OFDM system outperforms than other existing schemes.

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