Coded OFDM scheme for image transmission over time-varying multipath rayleigh fading channel

Orthogonal frequency division multiplexing (OFDM)is an excellent technique to reduce the effect of frequency selective in time varying multipath channels by dividing the transmission bandwidth into many narrow-band subcarriers, each of which exhibits an approximately flat fading. Cyclic extensions are added to OFDM symbols to allow time for mutipath signals from the previous symbol to die away before the information from the current symbol is gathered. In this paper, a modified OFDM scheme for image transmission is proposed. The new proposal is based on modification of the OFDM structure through using unequal power allocation for the successive OFDM symbols. Unequal cyclic time guard is also applied with unequal power allocation. The proposed method is compared with the conventional OFDM. Results show that the performance is improved at lower average cyclic extension periods and lower average power when using the proposed method. The performance study of OFDM scheme is examined with and without forward error correction (FEC).