Improving Robustness of CDM Spread Spectrumwatermarking

This paper proposes improvements to the code division modulation and multiplexing (CDM) spread spectrum watermarking. The improved CDM technique exploits all the available information at the embedded and determines the required energy for the spreading sequences to achieve a specified bit error probability. This approach considers an additive noise in the channel and all the interferences from the host signal, cross-correlation between spreading sequences, perceptual masking and interferences from collusion attacks. We provide results to illustrate the improvements achieved and also comparisons with traditional CDM watermarking.