The Research Of Ultra-Wideband Anti-Interference Communication & Ranging

Ultra Wide Band (UWB) mechanism is to use the pulsing modulation to form spread spectrum signals for information transmission. USA, since middle 1990's, has developed several UWB radio communication, radar, imaging and high precision positioning systems, which have been applied practically as the UWB radio system in military equipment. At present, as both commercial and military communication, TT & C and positioning systems have high requirements for information security, the UWB signal, due to its much lower signal power compared with thermal noise, can be used for covert communication and has high anti-interference capability and low LPI, and its multi-user TT & C radio network access has the functions of network access authentication and ID authentication. This communication mechanism has high channel security and satisfies the requirement for high information security with combination with other information encryption techniques. Therefore, the study on UWB communication is very important for both military and commercial use.This paper mainly presents the research results in terms of the following aspects:1) Study on UWB pulse communication system, providing the implementation methods for that systemBased on the study on definitions and spectral characteristics of UWB signals, the modulation modes based on UWB spread spectrum signals, such as amplitude modulation (AM), delay phase modulation (PM) and PN-code combined modulation, and the demodulation modes for UWB signals are provided, the UWB receiving performance is computed and analyzed, and the schematic block diagram of engineering implementation for receiving is shown.2) Study on ranging and acquisition of UWB signals, providing 2 fast acquisition methods.This paper mainly studies the ranging method based on PN code combined impulse signals, analyzes the signal spectrums for PN-code impulse AM and delay PM, takes the AM signal as the example to analyze the full-coherent delay acquisition method, proposes two fast acquisition methods(square pulse phase acquisition first and then PN-code phase acquisition, and delay multiplication pulse phase acquisition first and then PN-code phase acquisition), calculates and compares the detection SNRs of several acquisition methods, and provides the principle block diagram for implementation of fast acquisition.3) Study on high dynamic UWB signal, providing the concept of time variant template and the method of matrix vector correlation for the first timeWith respect to the acquisition and tracking of high dynamic time variant UWB signals, in this paper a concept of time variant template and a method of matrix vector correlation are proposed for the first time, which establishes a matched filter framework in UWB-time-frequency domain based on fractional Fourier transform (FRFT) filter, solves the issue of detection for UWB time variant signal and satisfies the acquisition application under special conditions with UWB high dynamic. No the topic related material is found by searching in the literatures in China and abroad.4) As for the precision tracking of UWB signal, an implementation method for UWB impulse delay lock loop is proposed.Through theoretical calculation of loop tracking accuracy and performance under Gaussian white noise conditions, provided are the theoretical values of delay measurement accuracy for UWB impulse delay lock loop, and system simulation verification for multiple kinds of impulse signals is carried out. At last, the system simulation results of the hardware platform self-developed are compliant with the theoretical results. No this topic related report is found by searching in literatures in China and abroad.5) Study on UWB multi-user operation and networking performance, proposing a calculation method for UWB multi-user positioning accuracyThis paper introduces the standards and protocols for civil WLAN, proposes a novel UWB multi-target covert TT & C system for long/medium-distance multi-user TT & C, provides two multi-user networking signal systems—TH-PPM and TH-PAM, performs engineering computation for generation, modulation and coherent acquisition methods of that signal and BER of multi-target TT & C transmission; carries out computational analysis for multi-target acquisition and demodulation; carries out computational analysis of the multi-user positioning accuracy of that signal; proposes a topology for UWB multi-target TT & C network; analyzes the networking security authentication process; at last, provides related conclusions.6) As for UWB high-rate data transmission technology, two parallel modulation transmission methods with multiple PN codes and multiple Walsh functions are proposed, which can significantly increase transmission rate of UWB system and reduce inter-symbol interference and difficulty of practical engineering processing. In addition, this method is tested on test prototype. No this topic related report is found by searching in literatures in China and abroad.7) Study on UWB radio wave propagation and multi-path receivingThe space propagation approach of impulse modulation signal isstudied; on the basis of comparison with traditional signal propagation approach, an impulse signal space propagation model is proposed for long/medium-distance communication. The research and simulations show that the impulse modulation signals used have good capability of space multi-path resistance and have much better performance than traditional spread spectrum communication signal.8) As for UWB array signal space-time process, a novel method for composite weighted wideband spread spectrum array signal processing based on time domain analysis is proposed. For the first time, it is derived and proved that the delay measurement accuracy of an array system is the statistical average of that of all elements.This method avoids complex frequency domain focus algorithm through composite weighting processing of group-delay of the array signal, phase and amplitude. Based on our creative study on UWB array signal processing, a simple UWB space-time array processing method easy for engineering implementation is proposed, which can further improve the anti-interference capability of system on the basis of the inherent anti-interference capability of UWB signal. For the first time, it is derived and proved that the delay measurement accuracy of an array system is the statistical average of that of all elements with a mathematical method. No this topic related report is found by searching in literatures in China and abroad.9) Experimental study on UWB signal simulation and hardware platformMultiple simulation tests are performed for UWB signal acquisition, tracking, data transmission, multi-user communication operation and multi-path channel. Generation, modulation and demodulation technology is implemented on the UWB signal hardware platform self-developed. A special UWB hardware platform and 670ps impulse signal are realized and modulation/demodulation experiments for 1Mbps data are performed. These UWB modulation/demodulation algorithms are developed by our own and have independent IPR.