Chaos And Its Application Research In Ultra Wide Band Communication

Chaos is one of the most important discoveries in the 20th century. Chaos, which is generated by a deterministic nonlinear dynamical system, possesses many special characteristics:sensitive dependency on initial state, long-term unpredictability, wide-band spectrum, non-periodicity, and so on. These characteristics enable chaos to have attractive prospects and potential practical value in communication field. As a new short-range wireless communication technology, Ultra Wide Band (UWB) has some special advantages, such as signal concealment and having a high-speed data transmission rate in the dense multipath environment. So applying chaos in ultra wide band has become a new frontier subject, which is being more attention to many scientists.This paper mainly includes chaos and its applications in UWB communication.(1) Chaotic and hyperchaotic signal generators are designed. Signal generators of discrete Chebyshev map, continuous unified chaotic system and generalized Lorenz system and hyperchaotic Lii system are on focus. First of all, the simulation experiments of these systems through Matlab are carried out and the experimental results are analyzed. Then on this basis, the chaotic signal generators are designed by using traditional analog circuits. Meanwhile, Chebyshev sequence generator and unified chaotic signal generator are designed by Xilinx System Generator. The results show that:chaotic systems can be designed by the traditional analog circuit design method and the new method of digital circuit design. Although both of them have their merits and demerits, the latter is the development direction of designing chaotic signal generators.(2) The synchronization of Chaos and Hyperchaos systems are researched. At first, the synchronization methods of chaos are summarized, and an adaptive feedback synchronization method is studied in detail. Then, the synchronization of chaotic systems which parameters were known and unknown have done a theoretical analysis and simulation experiments respectively. At last, the synchronization of the generalized Lorenz and the hyperchaotic Lu system are researched, and their synchronization circuit is designed. The simulation results and circuits indicate that the adaptive feedback synchronization method is suitable for a wide range, steady and has a high accuracy. (3) Chaos'applications in UWB communication have been studied. The pseudo-chaotic time hopping (PCTH) modulation communication scheme and the chaotic pulse position modulation (CPPM) scheme are recommended, outlining the principles, implementation method and performance. Based on the analysis, an improved chaotic pulse position modulation signal structures is presented, then the Rake receiver's performance of it is analyzed and simulated in the indoor multi-path channel.