Spread spectrum communication using chaos

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This research aims at applications of chaos to information communication systems and it started for spread spectrum systems. It also covers cryptosystem and tends to develop into bioinformation processing systems. Up to the present, we have obtained the following results.1. In order to investigate availability of random sequences from]-dimensional maps for spread signals, we tested correlation properties from Tent-Map and Cut-Map. Then it has clarified that the maps exhibit useful auto-correlation and useful cross-correlation in wide parameter region. Then the usefulness is held for mtlltiplexed cases. Moreover, 2-dimensional maps exhibit better correlation properties than 1-dimensional ones2. Relating to information hiding, we developed an efficient cryptosystem by using an]-dimensional map. In this system, key, plain-text and chippertext correspond to a parameter, image and preimage, respectively. We have also shown that the system performance is improved dramatically by using a 2dimensional map which has both expanding and contracting dynamics.3. We have analyzed 4-dimensional hysteretic circuits which relate to implementations of 2-dimensional maps. Then fundamental theories have been established for the trapping regions, observable chaos generation and bifurcations. We have also investigated chaos and-fractal responses from an artificial neural cell for future developments into biocomputations.