Research On Synchronization In Monobit Uwbwireless Communication Systems

With the development of modern society, the requirement of the communication rate is greatly increased. The impulse radio ultra wideband (IR-UWB) system is a promising physical layer candidate of short range high rate communication system, as it can achieve high date rate with low power assumption and complexity.However, due to the wideband nature of UWBsignal, a lot of design challenges arise. First, In the IR-UWBsystem the information bering is quite narrow pulse. The width of pulse is generally 0.1 ns which leads to the difficulty of synchronization. Secondly, the radio frequency (RF) front end is very difficult to implement, for example the analog to digital converter (ADC) is very difficult to have high resolution with high sampling rate, say Giga samples per second (Gsps). The synchronization problem can be dealt with different methods, but traditional high resolution samples are not available in high rate UWBsystem. Hence it is of great importance to investigate the synchronization problem with low resolution samples, which is necessary for implementation of UWBsystem. In addition, there is not much work have been done to this critical issue, which shall distinguish our results from the current work.The thesis includes the following issues: the relationship of synchronization error, resolution of quantization and BER loss; The Estimation of Time Delay for monobit IR-UWBSignals and design of synchronizer structure.Our research contribution can be summarized as follows;1) In order to design good performance synchronizer, we first study the relationship of synchronization error, resolution of quantization and BER loss in AWGN channel and multipath channel. we derive the implicit expression. By simulation we could get the similar feature that with the increase of synchronization error BER loss increases and when resolution increases the acceleration increases. From the graph we could find out even when synchronization increases to 30ps the BER loss is still tolerant.2) After obtain the requirement of synchronization resolution, we consider the best limit of different synchronizers, namely Cramer-Rao lower bounds. In the beginning we use Bussgang theory to linearize monobit quantization by which we deduce the Cramer-Rao lower bounds in AWGN and multipath channel. In AWGN channel the Cramer-Rao Lower Bound is inversely proportional to SNR while In Multipath Fading Channel the Cramer-Rao Lower Bound increases when the number of path increases.3) We study the design of synchronizer structure based the discuss above. At first we analyze the optimal synchronizer structure which is too complex to realize in real system. Hence, we study feasible synchronizer and propose two-level interpolation synchronizer structure which get a good trade-off of performance and complexity.From the analysis above, the research on Synchronization In Monobit UWB Wireless Communication Systems reach a certain degree of depth and provide a guide to the design of synchronizer.