Analysis on unit maximum capacity of orthogonal multiple watermarking for multimedia signals in B5G wireless communications

B5G aims to meet the demands of today's growing mobile traffic and expand the communication space. Considering that the intelligent application to B5G wireless communications will involve the security issues of user data and operational data, in this paper, the maximum capacity problem of the multi-watermarking method in multimedia signal hiding is studied to alleviate the information security problem of B5G. In the analyzed multi-watermarking process, the Spread Transform Dither Modulation is employed. During the watermarking procedures, through Gram-Schmidt orthogonalization, we can obtain the multiple spreading vectors. Consequently, the multiple watermarks can be simultaneously embedded into the same position of multimedia signal. Moreover, the multiple watermarks can be extracted without affecting one another during the extraction process. In our research, we intensively analyze the effect of the size of the spreading vector on the unit maximum capacity; consequently, we discover the hidden theoretical relationship between the size of the spreading vector and the unit maximum capacity. Many experiments have been conducted to seek out the optimal parameter values, with which the method can achieve the highest robustness, on the premise of possessing high capacity and good imperceptibility.