Research On Acquisition Technology And Implementation Of Chirp-UWB System

Ultra-wideband communications technology has the merits of low power spectral density, low probability of intercept, immunity to multpath fading and low power consumption. So UWB has become one of the hot area of research and development of wireless communication.Present their research mainly focus on the short-range, high-speed applications, and with the expansion of communication distance, compare with the traditional IR-UWB and MB-OFDM system, it have many advantages for the Chirp Ultra-wideband systems,such as strong anti-offset ability, low transmission peak value power, simple synchronization implementation. So it has very broad application prospects on the expansion distance of wireless communications.The synchronization technology is one of the key technology of Chirp UWB system.Aiming at the wide signal bandwidth and multipath phenomena exist in the propagation, the communication technology in Chirp UWB and its synchronization schemes are deeply studied. The research includes the following topics:First, Chirp UWB research background and meaning is described, then the research status in Chirp UWB are introduced research status. Then the paper analys difficulties and challenges faced with extended distance during the Chirp UWB study, and further describe the main content of this article. At last, the Chirp UWB main key technologies are introduced.Second, the technologies of Chirp UWB signal acquisition are studied. This paper focuses on acquisition technology in the Chirp UWB based on De-chirp pulse compression, then acquisition model for the Chirp UWB system based on FFT spectrum analysis and complex polyphase filtering structure is established respectively. Then the acquisition principle is deeply analysed and the detailed mathematical derivation of the acquisition performance is propose, furthermore, the theory is verified through the simulation results. Afterwards, aiming at multipath fading channel, the scheme of acquisition in the multipath environment based on Hit Set is presented, and then the acquisition performance is analysed in detail, simultaneously, the scheme verified via the simulation results. Finally, to reduce the search space, this thesis study the search strategy of Chirp UWB , then the two-step search strategy and simulation analysis are presented.Third, the tracking strategy of the Chirp UWB signal based on the structure of De-chirp pulse compression is studied. Aiming at multipath environment, a multipath tracking method based on both the structure of polyphase filter structure and the geometric center method of weighted frequency is presented. Then, a tracking loop model is establised, and the performance analysis of the tracking loop is also given, in the end, the simulation verification of the tracking algorithm is presented, and the simulation results show that the tracking algorithm can achieve tracking the Chirp UWB signal.Fourth,the paper complete the acquisition and tracking algorithm design and implementation of Chirp UWB based on the De-chirp pulse compression and complex polyphase filter structure in the FPGA. First of all, we present the general hardware implementation structure, then the functional module design implementation of the acquisition and tracking module are presented. Simultaneouslly, timing simulation of these algorithm is also given with the Quartus and ModelSim SE 6.1f.