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Performance analysis of DWT based OFDM over FFT based OFDM and implementing on FPGA


Journal: International Journal of VLSI Design & Communication Systems
ISSN 0976-1527

Volume: 2;
Issue: 3;
Start page: 119;
Date: 2011;
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Keywords: FFT | DWT | OFDM | BER | Lifting scheme | Simulink

Growth in technology has led to unprecedented demand for high speed architectures for complex signalprocessing applications. In 4G wireless communication systems, bandwidth is a precious commodity, andservice providers are continuously met with the challenge of accommodating more users with in a limitedallocated bandwidth. To increase data rate of wireless medium with higher performance, OFDM(orthogonal frequency division multiplexing) is used. Recently DWT (Discrete wavelet transforms) isadopted in place of FFT (Fast Fourier transform) for frequency translation. Modulation schemes such as16-QAM, 32-QAM, 64-QAM and 128-QAM (Quadrature amplitude modulation) have been used in thedeveloped OFDM system for both DWT and FFT based model. In this paper we propose a DWT-IDWTbased OFDM transmitter and receiver that achieve better performance in terms SNR and BER for AWGNchannel. It proves all the wavelet families better over the IFFT-FFT implementation. The OFDM model isdeveloped using Simulink, various test cases have been considered to verify its performance. The DWTOFDMusing Lifting Scheme architecture is implemented on FPGA optimizing hardware, speed & cost.The wavelet filter used for this is Daubechies (9, 7) with N=2. The RTL code is written in Verilog-HDLand simulated in Modelsim. The design is then synthesized in Xilinx and implemented on Virtex5 FPGAboard and the results were validated using ChipScope.
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Tango Jona
Tangokurs Rapperswil-Jona