Joint Estimation Of Symbol Timing Offset And Carrier Frequency Offset In Data Aided OFDM System

Orthogonal Frequency Division Multiplexing mainly uses the Orthogonal multiple subcarriers to transmit data information flow.It has the advantages of high Frequency utilization and strong anti-interference ability,so it has been widely used in modern communication technology.The orthogonality of the neutron carrier in OFDM technology is a prominent feature of this technology,but it also makes OFDM signals vulnerable to synchronization deviation,which will lead to phase rotation of the signal and destroy the orthogonality between carriers,thus affecting the signal transmission.In order to solve the problem of synchronization deviation in OFDM transmission system,a training sequence data block with strong correlation is reconstructed based on the data-assisted synchronization algorithm,so as to realize the joint estimation of symbol deviation and carrier deviation.(1)This paper introduces the research background of the subject,and summarizes the research and development of synchronization algorithm,synchronization algorithm mainly introduces two types of data-assisted synchronization algorithm and non-data-assisted synchronization algorithm.(2)Secondly,the influence of the synchronization deviation of symbol timing synchronization,carrier synchronization and sampling clock synchronization on system performance is deduced,and verifies by simulation.The overall synchronization framework model of the transmission system is built according to the connection between synchronization deviation,and analyzes the synchronization process of the system.(3)Finally,the original synchronization algorithm based on training sequence is analyzed theoretically and verified by simulation,Considering the relationship between the original synchronization algorithm and the construction of the training sequence,an improved algorithm of joint synchronization deviation estimation is proposed.The improved algorithm mainly introduces the pseudo-random sequence weighting factor into the OFDM transmission signal,and constructs the OFDM symbols with conjugate symmetric correlation and the same transmission data as the synchronous sequence data block.The data block sequence has good auto-correlation and delay correlation.According to the special properties of the data block,the corresponding timing synchronous measurement function is proposed to estimate the accuracy Timing synchronization position is used to determine the FFT window demodulated by the receiver.Based on the completion of timing synchronization,carrier frequency offset is estimated by using the fixed relationship between carriers,and then carrier synchronization is completed.Simulation results show that the improved algorithm has a sharp peak timing synchronization,and effectively improves the estimation precision of carrier frequency offset,after the synchronization of the transmission error rate performance of the system is analyzed,which effectively proves that the signals bit error rate is declining,especially under the condition of low SNR,overcomes the traditional algorithm of the problem of low precision and good synchronization performance as a whole.