Research On Generalized Frequency Division Multiplexing And Its Application

Orthogonal Frequency Division Multiplexing(OFDM)has been widely used in the last generation of mobile communication.However,with the arrival of the fifth generation of communication technology,the future development of mobile communication has a trend of diversification and intelligence,and the requirements for transmission delay,rate,reliability and other performance are more stringent.Due to the inherent defects of OFDM,these performance indicators can not be effectively met.More flexible waveform design is needed to better meet these services and scenarios.This paper introduces a new multi carrier technology,and it focuses on the synchronization scheme of generalized frequency division multiplexing and channel estimation technology.The specific research contents are as follows:Firstly,the basic concept of Generalized Frequency Division Multiplexing(GFDM)is described,and some theories related to GFDM technology are explored,including the modulation and demodulation process of GFDM and the modem that reduces the complexity.Secondly,the synchronization problem of GFDM is studied.The synchronization error will bring great negative effects to the GFDM system.This paper studies an improved time-frequency synchronization algorithm that can be applied to the scene with large frequency offset.This algorithm can effectively calculate the frequency offset within the system bandwidth,and can give an accurate first path search range,which is obviously optimized compared with the existing algorithms.In addition,the timing synchronization algorithm based on statistical optimization is described to overcome the defect that the accuracy of the first path detection is not high when the number of available subcarriers is small.In addition,the channel estimation of GFDM is explored.Aiming at the serious problem of pilot signals suffering from Inter Carrier Interference(ICI)and Inter Symbol Interference(ISI),a channel estimation scheme based on index modulation is proposed.Index modulation technology is used to adjust the number of active subcarriers and sub symbols around the GFDM pilot symbols to reduce the interference of symbols at the pilot and improve the quality of channel estimation.Based on time-varying multipath channel,simulation results show that the channel estimation performance after interference cancellation is better.