A Study Of Cell Search Algorithm In LTE-A System

In LTE system, when a UE powers on in a cellular system, in order to access the network, user equipment should detect the primary synchronization signal(PSS) and secondary synchronization signal(SSS) in downlink signal from the surrounding base stations, this is initial cell search(ICS) procedure. When the ICS procedure is complished, UE can acquire the carrier frequency offset, time synchronization and also identify the cell ID.The purpose of studying cell search algorithm is improving the accuracy of the detection of cell ID and accurately estimating the carrier frequency offset, or minimizing the complexity of the algorithm, make that can been easily realized, so that the user equipment can be quickly and accurately synchronized with the base station and accesses to the network.This thesis firstly introduces the research status of the LTE-A, then overviews MIMO, OFDM and other techniques which the LTE-A system uses, as well as the downlink physical layer of LTE-A. This thesis focuses on the frame structures, PSS detection algorithm, SSS detection algorithm and CFO estimation algorithm. In the PSS detection part, introduces the traditional cross-correlation PSS detection algorithm and the differential cross-correlation PSS detection algorithm, then gives an improved partial cross-correlation PSS detection algorithm which has an excellent detection performance. In SSS detection part, analyses traditional coherent detection and non-coherent detection algorithms of SSS signal, then gives a new algorithm with better performance and lower complexity. In the frequency estimation part, first introduces the frequency estimation algorithm in OFDM system, which is based on the CP ML frequency estimation algorithms. Then, based on the detection result signal PSS, introduces cross-correlation estimation algorithm using local PSS signal which has been known to us. Finally, gives an improved PSS cross-correlation estimation algorithm.According to the simulation results, we can conclude that compared with the original algorithm, improved PSS detection algorithm and new SSS detection algorithm has higher correct detection probability of the cell ID. Compared with the original algorithm, improved frequency estimation algorithm has lower MSE, the estimation value is more accurate.