Robust watermarked image transmission on OFDM wireless network

In this paper, we first present successful transmission of watermarked image Lena using OFDM technique over AWGN wireless channel by using 256-PSK modulation technique. The performance analysis of this transmission is carried out. The visual quality of non-transmitted and transmitted signed images is quantified by computing PSNR. The extraction of watermark from signed image is carried out by using Cox´s algorithm. The statistical correlation parameter SIM(I, I*) and Bit Error Rate (BER) between the original and recovered watermarks are computed before and after transmission. In the second part of this experiment performance comparison of transmission of signed images is carried out by using two different modulation schemes - 16-PSK and 16-QAM. It is concluded that 16-QAM is better performed than 16-PSK scheme as far as the variation of PSNR, SIM and BER with respect to channel SNR is concerned. The simulation results for 16-QAM modulation scheme are further improved upon by applying (7, 4) Hamming Linear Block Error Correcting Code on image data.