| The wireless spectrum resource is in increasingly shortage due to the growing business of wireless communication, FCC point out that the root of the problem is not the lacking of spectrum, but the spectrum has not been fully exploited because of the currently used static spectrum allocation principles. Therefore, new wireless communications technologies with efficient wireless resource utilization have become the researching hotspot, in which the ultra-wideband technology and cognitive radio technology is the most representative. UWB technology is a substrate transmission technology which can make full use of existing spectrum resources and occupies the spectrum with existing wireless communication system by overlap sharing mode, but UWB systems can easily interference to other communication systems because of lacking the RF environment information in communicating process. Cognitive radio system is a smart communication system, having the abilities of adaptive parameters, but there is no implementation scheme now. Hence, introduce cognitive radio technology to ultra wideband systems, design a new smart communication system—cognitive ultra wideband systems. This new system has the advantages of ultra wideband systems, like high security, high data transmission, low power; furthermore, it also has the flexible spectrum utilization characteristic of cognitive systems. Based on this, it give a new solution of the difficult situation wireless spectral resources in.This thesis mainly works on the construct and key technique of the cognitive ultra wideband systems; and divides into following aspects:Firstly, considering the need of cognitive radio for the system-implementation and the characteristics of impulse radio ultra wideband, the necessity and the feasibility of the combination of cognitive radio technology and ultra wideband system are analyzed. Secondly, in order to solve the problem caused by short of data in cognitive user's spectrum detection, using the optimal window function, propose an improved algorithm of MTM-SVD; the results indicate that this improved algorithm well adapt the outside radio environments and automatically suppress noises, so improves the accuracy of spectrum sensing. Thirdly, to improve the pulse spectrum efficiency of ultra wideband systems and decrease amount of calculation, design two newly adaptive pulses for cognitive ultra wideband system; and according to the simulation results, both of them work well in orthogonality and anti-jamming. Finally, to achieve higher spectrum efficiency of cognitive ultra wideband system, using theory of markov chain shows the process of channel occupying and releasing when cognitive ultra wideband users come; propose spectrum handoff mechanism by releasing corresponding conflicted bands, which states this spectrum handoff process and calculate the transition possibility between adjacent state.At the end this thesis, summarize the research results and point out the following work.
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