Spread-space spread-spectrum technique for secure multiplexing

Spread-space spread-spectrum technique for secure multiplexing.

A novel technique for multiplexing complex images is proposed in which each image may be demultiplexed only if a set of random encryption keys is known. The technique utilizes the ability of the double random phase encoding method to spread a signals' energy in both the space and the spatial frequency domains in a controlled manner. To multiplex, images are independently encrypted with differen...

Secure spread spectrum watermarking for multimedia

This paper presents a secure (tamper-resistant) algorithm for watermarking images, and a methodology for digital watermarking that may be generalized to audio, video, and multimedia data. We advocate that a watermark should be constructed as an independent and identically distributed (i.i.d.) Gaussian random vector that is imperceptibly inserted in a spread-spectrum-like fashion into the percep...

Secure Spread-Spectrum Watermarking for Telemedicine Applications

This paper presents a secure spread-spectrum watermarking algorithm for digital images in discrete wavelet transform (DWT) domain. The algorithm is applied for embedding watermarks like patient identification/ source identification or doctors signature in binary image format into host digital radiological image for potential telemedicine applications. Performance of the algorithm is analysed by...

Orthogonal Code Hopping Multiplexing for Downlink in Spread Spectrum Communications

A statistical multiplexing scheme in orthogonal downlinks is proposed to accommodate more downlink orthogonal channels than orthogonal codewords for mobile stations. The number of allocable downlink orthogonal channels depends on the average burstiness of the channels. The statistical multiplexing scheme is called here as the orthogonal code hopping multiplexing (OCHM). Since the OCHM uses a pr...

Optimal binary sequences for spread spectrum multiplexing (Corresp.)