Enhanced DWT-OFDM communication system using wavelet domain equalizer with Co-CFO

For the design of Orthogonal Frequency Division Multiplexing (OFDM), the Discrete Wavelet Transform (DWT) offers significant benefits over the classic Discrete Fourier Transform (DFT). This article proposes a Joint Low Complexity Regularized Zero Forcing-Wavelet Domain Equalizer (JLCRLZF-WDE) as substitute to a Frequency Domain Equalizer (FDE) for improving the Multiple-Input-Multiple-Output (MIMO) DWT-OFDM. The results have been assessed using the Co-Carrier Frequency Offset (Co-CFO) Rayleigh fading channel. The proposed scheme's relevance is demonstrated by a comparison of its Bit-Error-Rate (BER) and simulated time with those of conventional schemes. The obtained results showed that the proposed JLCRLZF-WDE outperforms conventional equalizers, requiring only 0.82 dB additional SNR to match the BER performance of Linear Minimum Mean Square Error (LMMSE)-WDE at BER =  10-3, and 0.27 dB at BER =  10-4. In comparison, other equalizers, such as Linear Zero Forcing (LZF)-FDE and LMMSE-FDE based on DWT and DFT, require significantly higher SNR values to reach the same performance benchmarks, with differences ranging from 0.31 dB to over 15.35 dB. Additionally, the proposed scheme achieves a simulated time reduction of 3.17% and 12.4% compared to LMMSE-WDE based on DWT and DFT, respectively.