Key Technology Research Of Cell Discovery And Synchronization In 5G System

Widely use of mobile internet and popularity of smart terminal demand a better performance of mobile communication architecture and supporting technology.In order to ensure a more reliable and efficient communication system,research for the next-generation communication system,which is 5G,has been performed around the world.Innovative technologies such as massive MIMO,millimeter wave and so on has been proposed in 5G.Cell discovery and synchronization are the initial step when UE need to establish connection with the base station in mobile communication systems.The accuracy and speed of cell ID detection and synchronization have an important influence on the further communication.This paper mainly studies the challenges for cell discovery and synchronization in FBMC and UDN systems.Firstly,the paper introduces the background of cell discovery and synchronization and the scheme used in LTE/LTE-A.OFDM is described in detail and several classical synchronization algorithms applied in OFDM system are reviewed.Then,the method of synchronization sequences design in LTE/LTE-A is illustrated.Furthermore,the assignment of cell ID,the synchronization sequence generation method and the detection scheme of synchronization sequence are described.Different detection methods are presented,and their merits and demerits are analyzed and compared.Then,the paper presents some candidate transmission technologies studied in 5G.The new features of these technologies may bring some different problems into cell discovery and synchronization.The change of modulation method in FBMC will lead to a modification of cell search and synchronization scheme.The physical mapping method of synchronization sequences in transmitter and the sequences detection algorithm in receiver are designed for systems with FBMC.Simulation results demonstrate that the proposed scheme for FBMC system can reach a similar cell detection probability level as that in the OFDM system.For UDN,the paper proposes a novel cell discovery and synchronization scheme based on cell clustering,which is designed for the scenarios with dense distributing cells and strong interference.New synchronization sequence corresponding to cell cluster is put forward and some improvements of the traditional synchronization sequences are proposed to match with the new frame format.Detailed flow of the scheme is illustrated,too.Simulation is also carried on for this scenario,and the results show that the proposed scheme based on cell clustering used for UDN shows a robustness against strong interference.The performance improves significantly compared with traditional schemes.The complexity of the two new schemes are also analyzed.