Spread spectrum communication using chaos

本研究针对混沌在信息通信系统中的应用，从扩频系统开始。它还包括密码系统，并倾向于发展为生物信息处理系统。到目前为止，我们已经获得了以下结果。为了研究随机序列在扩展信号中的可用性，我们测试了Tent-Map和Cut-Map的相关特性。然后阐明了图在宽参数区域表现出有用的自相关和有用的互相关。然后在多路复用的情况下保持有用性。此外，二维地图比一维地图具有更好的相关性。针对信息隐藏的问题，我们采用了1维映射，开发了一种高效的密码系统。在本系统中，key、明文和chippertext分别对应一个参数、图像和预图像。我们还表明，使用具有扩展和收缩动力学的二维映射可以显著提高系统性能。我们分析了与二维映射实现相关的四维迟滞电路。然后建立了俘获区、可观测混沌产生和分岔的基本理论。我们还研究了人工神经细胞的混沌和分形响应，以用于未来生物计算的发展。

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.