Research On Synchronization Of Impulse-Raido Ultra-Wideband Communication System

Synchronization algorithms applied in IR-UWB (Impulse Radio-Ultra Wideband) communication systems are deeply studied in this dissertation. The advantages of UWB systems, such as low power spectral density, low complexity, low cost and high data rate, attract a lot of research in both academia and industry. As one important realization of UWB, IR-UWB uses discrete series of very narrow Gaussian pulses occupying very large bandwidth to carry information. That is much different from traditional communication systems with carrier. However, the distinct time-domain characteristic of 1R-UWB causes huge difficulty to achieve its synchronization.This dissertation focuses on the synchronization techniques of IR-UWB systems. Based on the comprehension of IR-UWB, the dissertation analyses the timing-acqusition of 1R-UWB systems in detail, and indicates the differences in synchronizing processing between IR-UWB and tranditional carrier systems. The dissertation designs a stepped synchronizing algorithm for the IR-UWB receiver based on OSCR (Orthogonal Sinusoidal Correlating Receiver), to meet with the requirement of low complexity and low power; the algorithm is proved theoretically, and is realized in a demo system. Besides, the dissertation also analyses the receiving principle and synchronization of mono-bit receiver, which will be the most popular 1R-UWB receiver in the future. The main contributions of the dissertation are listed followed:1. The similarity between the second Gaussian derivative pulse and the sinusoidal plate is indicated, which provides the theoretical basis for the use of sinusoidal plate in correlating receiver; and the following research obtains the timing-precision requirement of each synchronizing level for two kinds of receivers based on sinusoidal plate. And then, a stepped synchronizing algorithm for OSCR is proposed.2. The process of the correlated data in each synchronizing level of OSCR is described in detail, whose validity is theoretically proved, and its simplicity to realize is discussed. The thesis also analyzes the time needed for the pulse-searching procedure in multipath environment using Markov Chain.3. The dissertation provides the solutions for the problems in design and achieving the synchronizing algorithm, such as the design of the frame, especially the training sequence as the frame head; the application of SSC (Switch and Stay Combining) as the multipath combining scheme; semi-auto-adapted frequency synchronization method; and some techniques for the realization in FPGA.4. To make the 1R-UWB receivers more systematic and integrated, this dissertation investigates the receiving principle of IR-UWB receiver based on mono-bit sampler, and analyzes the timing-precision requirement of each synchronizing level. At last, a feasible synchronizing scheme for mono-bit IR-UWB receiver is provided.5. According to these researches, this dissertation provides a set of stepped synchronizing algorithm for IR-UWB communication system. The algorithm has been applied in an IR-UWB demo system in a 863 project, which has a very high data rate and steady communication effect. This system proved the validity and good performance of the synchronizing algorithm.