LTE Downlink Synchronization Research And Physical Layer Demonstration System Realization Based On SDR

On December5th,2013, Ministry of Industry and Information granted LTE licence to mobile operator, hence another member is added to communication systems in China. With more and more communication systems, operators has to attachimportanceto how to lower the cost of constructing and maintaining the network. In this context, the concept of C-RAN is introduced. The theoreticalbasis of C-RAN is Software Defined Radio(SDR), i.e., realizing different base band processing procedure on a general hardware platform. The project supporting this paper is achieved with the cooperation of Beijing France Telecom R&D Center in the C-RAN feasibility context.This paper realized an LTE physical demonstration system which is able to transmit streaming media data. This system is realized by utilizing peripheral developed by France Telecom and OpenairInterface open-source. All the base band processing procedure is completed by the software in GPP. To achieve the aim of precisely timing, this paper proposed a scheme combining software and hardware time stamp. In this situation, software doesn’t need to consider timing and executionsequence of threads so that simplified the developmentprocess of software. In addition, this paper developed an integralprocess of downlink synchronization for the system. Though the physical layer specification is almost impeccable, the algorithm for receiver is still the researchemphasis of engineers. So a new downlink coarse synchronization method is proposed and proved by simulation.This system already has almost all the function of LTE physical layer and can guarantee the transmission of data. It verified the feasibility of realizing wireless communication system on GPP. The new downlink coarse synchronization algorithm provide a reference for other system design.