The Research Of LTE Descending Synchronization Technology In The Private Network

LTE is the most important project by3GPP in this nearly years. Whereas, theTD-LTE is mainly used in public mobile networks, also, it is mentioned in somereferences that the TD-LTE is suitable for private networks. The time and frequencysynchronization is the most important issue that must be deal with for TD-LTE systems,many arithmetic for synchronization focus on TD-LTE in public mobile networks arepublished,but these arithmetic may not be suitable for private networks because of theenormously difference between the private network and public network,which showus the significance of the research on the synchronization of TD-LTE in privatenetworks. So, the mission of the work is to improve the performance of time andfrequency synchronization.The primary characteristics of the private network systems in this article can besummarized in three points. Firstly, it should be fit on many atrocious entironment,sush as high or low temperature and air pressure.These factors affect the frequencyoffset and phasic noise. Secondly, the base station in this private network needsflexibility,which limit the height and position of the base station,which also limit thetransmit power of the base station. Furthermore, this private network system is mostlyused in mountain forest,where have less sector but need larger area forcommunications,which advance better performance when the SNR is poor,as well asthe multipath involved. Thirdly, the system have less time for synchronization.This article is absorbed in these three problems,and obtain these outcomes:1. In order to improve the disadvantage of timing synchronization get worse whenfrequency offset having a bad value, the idea that pre-estimation on integer carrierfrequency offset in time domain is proposed. The simulation indicates that thisalgorithm has a excellent performance when the frequency offset get4subcarriers.2. In order to improve the disadvantage of the complexity of the calculation, theidea that coarse timing synchronization based on cycle prefix (CP) and fine timingsynchronization based on existing algorithm is proposed. The simulation indicates that this method could reduce the complexity greatly.3. In order to improve the disadvantage of performance integer carrier frequencyoffset estimation on the multipath-fading channel, the idea that the symmetricalcorrelate on synchronization signal in integer carrier frequency offset estimation isproposed. The simulation indicates that this method has an excellent performance onITU-A-120channel model.This paper proposes the whole scheme based on the practical requirements of theprivate networks. The scheme including: AGC,timing synchronization, frequencyoffset estimation, and loop tracking.The simulation indicate that this scheme is robustunder ITU-A-120channel model.