Research And Simulation Of Performance And Synchronization Technology Of Frequency-Hopped OFDM System

Orthogonal frequency division multiplexing (OFDM) which has advantage of high spectrum efficiency, resistance to multipath interference is multi-carrier high-speed transmission technology in wireless environment, it has become a candidate of physical layer technologies of the next-generation wireless communication systems, while military communications also has a good prospect. Meanwhile, because of excellent anti-jamming performance, frequency hopping alsohas been widely used in civilian and military communication mobile communications.In order to improve the shortage in the traditional frequency-hopping communication systems , such as,low hopping rate , low transfer rate,according to the advantages of OFDM technology, we can realize frequency hopping communication by constructing frequency hopping OFDM communication system.On the basis of large amounts of datas,this paper mainly elaborates basic principles , structure and composition ,and key performance indicators of Frequency Hopping (FH) communication system, introduces the production and development background,the structure and composition of orthogonal frequency division multiplexing (OFDM) communication system. According to this, two kinds of frequency hopping OFDM forms(sub-carrier hopping and RF frequency hopping ) was summed ,and introduced their advantages and disadvantages. At the same time, the paper simulate the results using QPSK and 16QAM modulation in AWGN and Rayleigh channels, According to this paper, we can see the frequency-hopping OFDM is a more efficient OFDM modulation technology, it will be have a broader space in military communications in the future.This fourth chapter described the frequency-hopping OFDM system parameters and data packet structure, introduced the frequency-hopping OFDM timing synchronization and carrier synchronization algorithms, and then, this paper discussed the Influence of the carrier frequency offset estimate with long and short training sequence .and simulated with matlab to the frequency hopping OFDM timing synchronization and carrier synchronization algorithms. The simulation results show that: (1) in the timing synchronization algorithm, based on OFDM delay correlation algorithm can accurately locate the starting point of a symbol. (2) in the carrier synchronization algorithms, OFDM-based correlation algorithm can effectively delay the estimated carrier frequency offset, from the mean square error of the results, the results can able to reach 10-4 in the 8dB above, which proves this estimation method is effective.(3) use OFDM pilot ,we can reclamated constellation, this method with in QPSK and 16QAM modulation mode, in AWGN and Rayleigh channels are feasible .Finally, describes the frequency-hopping TDMA networks OFDM synchronizationThrough this simulation can be seen: In this paper the proposed frequency-hopping OFDM communications system architecture design is reasonable, system performance and analysis of simulation results with a theoretical reference value. The mothed Used for frequency hopping OFDM timing estimation and frequency offset estimation is feasible.