Voice and Image BER Analysis of the OFDM System with MECCT and MLNST Companding Techniques Over Mobile Radio Channels

In a single carrier system, a deep noise of fading can destroy the whole link. However, for the multicarrier scheme, a minute proportion of subcarriers are only being damaged. Using the multicarrier modulation overlapping technique, half of the bandwidth can be saved. Orthogonal frequency-division multiplexing (OFDM) is a multicarrier modulation and is widely used in broad band communications, 3rd to 5th generation networks, WLAN, WIMAX, multimedia transmission, etc. The OFDM system minimizes multipath effects such as inter-symbol interference (ISI) and inter-carrier interference (ICI) thereby increasing system capacity to accommodate a higher number of users. The objective of this paper is to improve the power efficiency (bit error rate (BER)) of the OFDM system using companding techniques. The BER performance analysis of the OFDM system over mobile radio channels, such as additive white Gaussian noise channel (AWGN) and Rayleigh fading channels are studied, analyzed, and implemented using MATLAB for voice and image. The bit error rate (BER) of the OFDM system with modified exponential companding with clipping transform (MECCT) and also with modified linear non-symmetrical transform (MLNST) companding techniques are compared with that of the OFDM system and the OFDM system with linear non-symmetrical transform (LNST) companding technique over AWGN and Rayleigh fading channels. The MECCT-based system has less BER and it saves bandwidth of 2.0 dB over AWGN channel.