Performance Enhancement of Bit-Level XOR Compressed Image OFDM Transmission Systems

The bit error rate (BER) formula of the M-QAM system is derived under nonequally likely condition of the constellation points, from which improving the BER performance of the M-QAM system by optimizing the probability distribution of constellation points is identified. Based on the analysis, the bit-level XOR method is employed to encrypt the image data and modify the probability distribution of the constellation points. The simulation results show that bit-level XOR is helpful to obtain a better probability distribution of the 16-QAM system compared to that without bit XOR and hence can improve the BER performance of the proposed OFDM transmission system. Simulation results based on test images over the AWGN channel further confirm that the reliability of the OFDM transmission system and the reconstructed quality of the compressed image are both significantly enhanced using bit-level XOR operation.