The Simulation And Implementation Of Downlink Synchronization Technology In LTE-advanced Communication System

In the past twenty years,we have witnessed the rapid development of wireless communication system.As wireless multimedia traffic is increasing far more rapidly than voice and will increasingly dominate traffic flows,the users put forward higher requirements for the rate of data transfer in wireless networks.So the LTE system,the aim of which is to improve the data rate,reduce the delay,cut the cost and increase the system capacity,is proposed by 3GPP.As an enhanced version of LTE,LTE-Advanced has become the most popular technology in the field of wireless communication,so the research on LTE-Advanced system has important practical implications.The LTE-A system is mainly based on OFDM technology.The advantages of OFDM system include the high spectrum efficiency,the ability of anti-multipath interference and the simple channel equalization.Compared with the single carrier systems,however,the OFDM system is much more vulnerable to the impact of the timing error and frequency offset.This thesis systematically analyzes how the timing error causes inter-symbol interference and how the frequency offset can lead to inter-carrier interference,which indirectly stresses the importance of the synchronization for OFDM system.In the actual application, the complexity of the environmentand the relative movementbetween the base station and the user equipment need to be taken into account.This thesis also introduces the influence of wireless mobile channel in OFDM system,which lays a theoretical foundation for the downlink simulation.Synchronization is a key step in the cell search in a LTE-A system.This thesis analyzes sevral time domain detection algorithms of the primary synchronization signal and one frequency domain detection algorithm.We use the channel estimation of the primary synchronization signal to compensate the secondary synchronization signal because the primary synchronization symbol and secondary synchronization symbol are adjacent structurally.At the same time, due to the special nature of the secondary synchronization signal itself,we quantify the symbol during the detection.Finally,RTL-level design is carried out on the proposed solution.The hardware design includes the primary synchronization signal detection module,frequency offset estimation and compensation module,OFDM demodulation module and the secondary synchronization signal detection module.Under the premise of ensuring the basic function of the primary synchronization signal detection module,we adopt folding transformation technique in order to save the hardware resources.