Reshearch On CNN Hyperchaotic Properties And Its Application In Space Multi-objective Telemetry Systems

Cellular neural network(CNN) is a kind of nonlinear circuits with large scale, which is based on Hopfield neural network and cellular automaton. CNN has lots of parameters. When the parameters meet some conditions, it will generate the phenomena of chaos or hyperchaos. Cause of the sensitivity to initial value, the hyperchaotic sequences generated by CNN hyperchaotic system have good Pseudo-random properties and have the potential to be applied in CDMA systems. Besides, CNN has good collateral signal processing capabilities, which can be used for multi-user detection in Code Division Multiple Access(CDMA) systems. Currently, the communication and data transmission in the space multi-objective telemetry systems are usually based on the CDMA and divide different satellites with different spread spectrum sequences. Therefore, the research on CNN hyperchaos can surely be applied in it and the research on CNN hyperchaotic systems is very necessary.We firstly researched on the properties of the CNN hyperchaotic systems. By setting up the model of high-dimensional full-interconnected CNN, we analyzed the properties, such as sensitive to initial value, bounded, traversing, Lyapunov exponents and strange attractor. Based on the properties above, we proposed a CNN hyperchaotic system judgment and selection algorithm, with which, we can select those hyperchaotic CNNs from lots of CNN systems. This is the basis of the later studies and is the source of the hyperchaotic systems we need.Secondly, we researched on the hyperchaotic spread spectrum sequences. Through analyzing the properties of t he hyperchaotic spread spectrum sequences quantitatively, we found that not all the hyperchaotic spread spectrum sequences have good properties. A selection algorithm for CNN hyperchaotic sequences, which is based on the digital evaluation indexes of sprea d spectrum sequences, is thus proposed to generate the spread spectrum sequences with good pseudo-random properties. By applying the selected CNN hyperchaotic spread spectrum sequences in CDMA systems, we can improve the capacity, BER and secrecy performance of CDMA systems.Thirdly, we researched on the multi-user detection in CDMA systems. A CNN based multi-user detection algorithm is proposed by combining the optimal multi-user detection algorithm and the CNN Lyapunov function. And to the problem that it is easy to Trapped in local minimum point of Lyapunov function, we simplified the algorithm proposed. The simplified algorithm can reduce the multiple access interference in CDMA systems effectively.At last, we applied the CNN hyperchaotic systems in the communication and data transmission in space multi-objective telemetry systems. We set up the model of the communication and data transmission system, designed the specific communication scheme, and applied the CNN hyperchaotic spread spectrum sequences and the simplified multi-user detection algorithm based on CNN in the sending and receiving ends of the system, respectively. And the BER and secrecy performance of the system is improved successfully as a result.