Aanchal Jhingan ¹, Lavish Kansal ¹

Affiliations
1 School of Electronics and Electrical Engineering, Lovely Professional University, Phagwara – 144411, Punjab, IN

Abstract

OFDM systems due to its orthogonality factor provides significant spectrum efficiency, robustness to fading and simple cost effective implementation. One of the factors that effects the OFDM system performance is the Carrier Frequency Offset (CFO) that results in the Inter-Carrier Interference (ICI) which causes a degradation of the OFDM system performance. In this paper, a discussion on the performance of Discrete Wavelet Transform (DWT) OFDM and Fourier Transform (FFT) OFDM is done by considering the presence of CFO in both the systems. A comparative study of both the systems is done on the basis of Bit Error Rate (BER) performance these systems show. The system is considered on the basis of improvement in the BER. Simulations conclude that the system that uses wavelet implementation performs better than the conventional OFDM system. The DWT performance even with CFO factors shows considerable improvement in the bit error performance than the FFT based traditional system. Further, the whole simulation is done under the Rayleigh channel, the performance calculated for five practical values of CFO from 0 to 0.2 with step difference of 0.05. The BER performance is simulated using MATLAB software. Further, the whole simulation is done under the Rayleigh channel, the performance calculated for five practical values of CFO from 0 to 0.2 with step difference of 0.05. The DWT based OFDM outperforms the FFT based OFDM for all the values of CFO.

Keywords

BER, CFO, DWT, FFT, ICI, IDWT, IFFT, ISI, OFDM

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Aanchal Jhingan ¹, Lavish Kansal ¹

Affiliations
1 School of Electronics and Communication Engineering, Lovely Professional University, Phagwara - 144411, Punjab, IN

Abstract

Orthogonal Frequency Division Multiplexing (OFDM) is a multi-carrier based system that is selected to be used in the broadband wireless communication system. However, the main drawback considered for OFDM system is the Carrier Frequency Offset (CFO) which causes the Inter-Carrier Interference (ICI) that degrades the performance of the OFDM system. This paper discusses the performance of the system based on Bit Error Rate (BER) in the presence of CFO. For this, the estimation of CFO is carried over in both Discrete Wavelet Transform (DWT) OFDM and FFT OFDM for five different values of CFO (CFO = 0, 0.05, 0.1, 0.15, 0.2) in AWGN (Additive White Gaussian Noise) channel using the same procedure and their BER performance are simulated using MATLAB software. A comparative analysis on FFT-OFDM and DWT-OFDM systems is offered that shows that the performance given by DWT-based OFDM system is better in comparison to the FFT based OFDM system. BER results are simulated for BPSK, QPSK, 8-PSK, 16-PSK, 32-PSK modulations for both DWT and FFT based OFDM models. The analysis of MATLAB simulation clearly shows that the DWT-OFDM offers an improvement of 5-10 dB for the diverse order of modulations over AWGN channel.

Keywords

CFO, DWT, FFT, IDWT, IFFT, OFDM

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Aanchal Jhingan ¹, Lavish Kansal ²

Affiliations
1 Department of Electronics and Communication Engineering, Lovely Professional University, Punjab, India, IN
2 Department of Electronics and Communication Engineering, Lovely Professional University, Punjab, IN

Abstract

Orthogonal Frequency Division Multiplexing (OFDM) is a popular kind of multi-carrier based transmission technique that has found its applications in some wireless and wireline systems. But this system suffers from several facts that degrade its performance resulting in the interference of sub-carriers. Carrier Frequency Offset (CFO) is considered as one of the factor that causes interference in the system, leading to an Inter-Carrier Interference (ICI) between the carriers that results in a degradation in the performance factor of the system. In this research work, a comparative estimation is done on the Bit Error Rate (BER) performance of Discrete Wavelet Transform (DWT) OFDM and Fourier Transform (FFT) OFDM in the presence of CFO in both of the given systems. The research focuses mainly on the improvement of the BER in the system. The complete analysis is done by considering the channel to be Rician and the systems performance is estimated for some practical values of CFO. The complete simulation is done in the MATLAB. As the CFO increases the error in the system also increases, but still in that situation, DWT shows better improvement than the conventional system. The BER performance of OFDM systems shows improvement for all the diverse PSK modulation.

Keywords

BER, CFO, DWT, FFT, ICI, IDWT, IFFT, ISI, OFDM

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Aanchal Jhingan ¹, Lavish Kansal ¹, Navdeep Singh Dhaliwal ¹

Affiliations
1 School of Electronics and Electrical Engineering, Lovely Professional University, Phagwara – 144411, Punjab, IN

Abstract

A multiplexing technique named Orthogonal Frequency Division Multiplexing (OFDM) has been widely used in a broadband wireless communication system. This technique can provide the larger data rates with the capability of showing enough strength to the impairments caused by the radio based channels. The OFDM based systems are supposed to be sensitive towards the errors that originate due to the frequency mismatch in the form of the Carrier Frequency Offset (CFO) effect. That further leads to an effect named Inter-Carrier Interference (ICI). ICI mainly occurs due to the inconsistency in the frequencies of the local oscillators that are present together at the transmitter and the receiver side. For compensating the effect of the CFO, the researchers have proposed different types of methods and algorithms used for estimation and its correction by now. In this research, the reason for the generation of the CFO and its effects are shown on the performance of the system is studied. The main algorithms and techniques for the CFO estimation and correction are reviewed and discussed in the literature briefly and also discussed a proposed and an efficient method for the estimation and compensation of the CFO is proposed.

Keywords

BER, CFO, ICI, ISI, OFDM.

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