| In recent years, there has been a great interest in researching and applying Orthgonal Frequency Division Multiplexing (OFDM ) technology into high-speed wireless communications.OFDM based digital communication systems are robust in multipath environment. Moreover,OFDM can achieve high bandwidth efficiency and can be implemented with a simple structure.These advantages make OFDM technology particular suitable for high-rate data transmission in wireless environments.OFDM system is sensitive to frequency offset, so synchronization is one of the important technologies of OFDM .This thesis is mainly focus on the research of synchronization techniques in OFDM systems.The principle of OFDM system is presented in the beginning of this thesis ,and the effect of OFDM key technologies to its system performance is analyzed.After OFDM frame structure based on std IEEE 802.11a is presented, Simulations of OFDM baseband system model based on SINULINK are presented. Baesd on mathematical analysis of OFDM synchronization, the effects of OFDM synchronization errors,such as carrier offset,sample error and symbol timing error,are analyzed. The results show carrier frequency offset and sample interval error introduce Inter-Carrier-Interference (ICI), and carrier phase error, symbol timing error and sample timing error introduce signal phase circumvolution.At last, the algorithms of packet detecting,symbol timing, carrier frequency synchronization and carrier phase tracing are presented. All the algorithms are test against AWGN and multipath channel and analyzed,and then the better algorithms are chosed to compose a complete synchronization schemes. Results of sinulation and analysis show considerable performance using the synchronization scheme. |
PDF Full Text Request