Research On Channel Estimation And Synchronization Technology In FBMC System

Due to its low spectral efficiency and sensitivity to carrier frequency offset,OFDM cannot meet the new requirements and application scenarios in next-generation mobile communications system.In order to solve the problem of OFDM,the Filter Bank Multi-Carrier Technology(FBMC)has been extensively studied.The FBMC system does not use the cyclic prefix(CP),so it has a high spectrum utilization rate.And with a well-designed prototype filter,the system has a low out-of-band leakage.Based on these advantages,FBMC technology is expected to become the modulation technology in next generation of wireless communications.Since the FBMC does not satisfy orthogonality in the complex domain,which is strictly orthogonal only in the real-number domain,which means that there is intrinsic imaginary interference on each sub-carrier,so the traditional channel estimation method in the OFDM system cannot be directly applied to the FBMC system.Moreover,unlike OFDM,the FBMC system does not use CP,which makes the system sensitive to timing errors,so it is very important to design a synchronization algorithm with superior timing performance.The article mainly studies the channel estimation and synchronization technology of FBMC system.The specific work is as follows:1)A new channel estimation algorithm based on interference cancellation is proposed.By analyzing the response of each data point in the system,the algorithm designs a pilot sequence that occupies only two data symbols.The two columns of pilots have the same or the opposite value of interference in the corresponding position in the frequency domain.After a simple linear processing at the receiver side,the interference existing in the system can be eliminated.The theoretical analysis and simulation results show that compared with the traditional channel estimation algorithm,the algorithm has lower complexity and lower spectral resource consumption,and has better error performance and smaller under low SNR conditions.2)A new iterative based system timing synchronization scheme is proposed.In the iterative process,different methods are used for rough timing synchronization and fine timing synchronization.Firstly,the ZC(Zadoff-Chu)sequence delay correlation is used to estimate the coarse timing by cross-correlation.After the coarse timing synchronization compensation,the auto-correlation is used to estimate the carrier frequency offset,so that better frequency offset estimation performance can be obtained.Then,the estimated frequency offset is subjected to sequence compensation,and finally,the fine symbol timing synchronization is performed using the compensated sequence.Compared with other algorithms,it can be concluded that the proposed algorithm can obtain high precision of timing accuracy when there is frequency offset in the system.