Synchronization Technology Of Distributed MIMO-OFDM

With the rapid development of communication technology,people are demanding high technology communications,but the limited spectrum is a constraint to the development of communication.Because the future fourth generation mobile communication system need high capacity and high data transfering rate,it requires a very high spectrum efficiency technology.The MIMO-OFDM technology can improve system capacity and spectrum efficiency in the limited spectrum,and it is also resistant to the multipath fading channel.So the MIMO-OFDM technology is one of the key technologies of 4G MMO-OFDM technology is composed of multiple-input multiple output technology and OFDM technology. MIMO technology have multiple antennas, and they simultaneously transmit and receive signals, the system can increase the channel capacity,and it does not need additional spectrum resource and the antenna transmit power.The OFDM technology makes the channel into multiple subchannels,each subchannel is modulated with a subcarrier.because each subchannel can be viewed as a flat fading channel,so it can be effective resistant to frequency selective fading. it has orthogonality between subcarriers,so it can effectively improve the spectrum efficiency. People make a lot of research in the MIMO-OFDM technology in recent years.However,MIMO-OFDM system demands extremely in the time domain and frequency domain synchronization,so the synchronization is one of the key technologies of the MIMO-OFDM system.Frequency deviation would destroy the orthogonality between subcarriers,causing interference between subcarriers.If the deviation of the time domain is in the out of the cyclic prefix,it would cause inter-symbol interfernce and the interference between subcarriers.People make a lot of researches in the synchronization of MIMO-OFDM and OFDM technology ot solve this problem in recent years.This thesis analyzes the OFDM system model and its synchronization errors,and it also analyzes the MIMO-OFDM system model and its synchronization errors. Synchronization methods can be divided into methods based on secondary data and methods based on no secondary data The synchronization used in this paper is based on secondary data.This thesis introduced some typical synchronization algorithm of the MIMO-OFDM system and OFDM system,and make comprehensive research in it.This thesis proposes a new constructing method of the leading symbol on the basis of the previous synchronization,and gives the correspongding synchronization algorithm,simulation results show that the effect of this scheme is superior than the previous program.In order ot make this scheme more practical,we improves it and also gives the corresponding synchronization algorithm.The simulation results show that the improved scheme can accurately get the beginning of each path.Sepcific structure of this paper is as follows:The first chapter introduces the history of the mobile communication and the MIMO-OFDM technology.The second chapter introduces the model of OFDM system,synchronization error analysis and some typical synchronization algorithm.The third chapter introduces the model of the MIMO-OFDM system,synchronization error analysis and some typical synchronization algorithm.The forth chapter proposes two different leader sequence baseed on CAZAC sequence for the single path and multipath of the channel,and gives the corresponding synchronization alrorithm.Chapter V of this paper summarizes the research work.