Synchronization Algorithm Research In IR-UWB Wireless Communication System

The main content of this thesis is researching the acquisition algorithms of synchronization in IR-UWB(Impulse-Radio Ultra-WideBand)communication systems. The advantages of UWB systems, such as low cost, low power waste, low complexity and high data rate, attract lots of interesting in both academia and industry recently.Synchronization between transmitter and receiver is the key technology in communication systems, especially in IR-UWB communication system which usually applied in burst communications. IR-UWB systems use discrete ultra narrow pulse series to carry information, which is different from other wireless communication systems. Firstly, due to the power limit of FCC(Federal Communication Commission), the power of transmitted signals is very low, and the power spectral density exist below the noise level at the receiver because of the huge band width caused by ultra narrow pulses. It will spend the receiver a long time to make reliable decision. Secondly, it is difficult to complete the acquisition of the received signals, for the search space is very large due to the fine time resolution caused by the low duty cycle of the ultra narrow pulses. So, there's always going to be a challenge in the design of structure for a receiver in UWB communication systems.In dense multi-paths environment, the transmitted signal power is distributed to too many multi-path components, however, these multi-path components which can be resolvable in time domain may speed up the acquisition process. This is because we assume that the acquisition is completed when any one of the multi-paths is acquired in the acquisition stage. Based on this assumption, the true phase position can be found rapidly once the coarse synchronization of the receiver located the multi-path cluster in the search space.We research the characterization of the multi-path channel firstly, and analyze the acquisition performance of the several search methods. Then introduce the process of serial search. Based on these theories, we propose two algorithms for acquisition in dense multi-path environment. Both of these two algorithms divide the search space into several subspaces, then find the subspace which include the true phases rapidly in the first step and locate the true phase in the second step within that subspace. From the result of simulation, we can see that both of the algorithms can complete the acquisition rapidly with low mean search time.