OFDM is a multicarrier transmission technique, widely preferred due to advantages like high data rate, less bandwidth consumption and channel robustness. IEEE 802.11a standard uses conventional OFDM which uses IFFT for generating orthogonal carriers and multiplexing. Due to extra bandwidth consumption by cyclic prefix in conventional OFDM, DWT has now emerged as new alternative over FFT. It offers advantages like increased spectral efficiency, better orthogonality and less bit error rate. Performance degradation due to frequency offsets has been reported in literature. Carrier frequency offset (CFO) arises due to Doppler shift and imperfect synchronisation of transmitter and receiver. CFO results in inter-carrier interference that effect BER. In this paper, we investigated the offset effect on conventional and DWT-based OFDM under different communication channels (AWGN and Rayleigh). Effect of different modulation techniques and wavelets on DWT-OFDM model is also analysed.

OFDM是一种多载波传输技术，由于具有诸如高数据速率，较少的带宽消耗和信道健壮性之类的优点而广受青睐。IEEE 802.11a标准使用常规的OFDM，该OFDM使用IFFT生成正交载波和复用。由于常规OFDM中循环前缀的额外带宽消耗，DWT现在已成为FFT的新替代方案。它具有诸如提高频谱效率，更好的正交性和更低的误码率等优点。在文献中已经报道了由于频率偏移而导致的性能下降。载波频偏（CFO）由于多普勒频移以及发射器和接收器的不完全同步而产生。CFO会导致影响BER的载波间干扰。在本文中，我们研究了在不同通信信道（AWGN和瑞利）下传统和基于DWT的OFDM的偏移效应。还分析了不同的调制技术和小波对DWT-OFDM模型的影响。