Research Of Key Technology For Frequency Hopping Synchronization Systems

Frequency hopping(FH) is a spread-spectrum communication technology, which has been widely used in mobile communications due to its advantages in anti-jamming, anti-intercept and confidentiality. Synchronization is one of the key technology in frequency-hopping communication. Establishment time and reliability of synchronization directly affect the performance of frequency hopping system. Therefore, the study of synchronization technology in frequency hopping communication has important application value and significance.This thesis focuses on the key technologies of frequency hopping synchronization system, including: synchronization scheme and frame format design of frequency hopping communication system, synchronization acquisition, timing synchronization and frequency offset estimation algorithm. Simulation has been implemented on these algorithms.The major work of this thesis are summarized as follows,Firstly, system design of frequency hopping synchronization has been completed. This thesis designed system parameters and frame format, proposed a frequency hopping synchronization scheme based on local clock information(Time of Day, TOD) and synchronous prefix. Then this thesis design the TOD format and synchronization frame format, synchronization frequency generation algorithm, capture sequence and leader sequence, elaborated synchronization acquisition and tracking scheme.Secondly, this thesis studied the synchronization acquisition scheme based on TOD and synchronization prefix, derived the performance of serial and parallel acquisition algorithm on acquisition time and acquisition probability, then implement simulations of these two algorithms in AWGN channel and the fading channel. The results show that both serial and parallel acquisition algorithm have a good performance of synchronization acquisition in AWGN and the fading channel,and meet system performance requirements.Finally, this thesis studied and simulated the timing synchronization algorithm and frequency offset estimation algorithm of frequency hopping synchronization system. Simulation results showed that the performance of the timing synchronization is insensitive to initial frequency offset. The estimation error can be reduced based on the basis of sequence correlation-based timing synchronization with pulsing interpolation algorithm. Both timing synchronization algorithms can meet system performance requirements, and estimation error of timing synchronization algorithm has almost no impact on TODL detection probability. Under the existing parameter settings, the frequency offset estimation performance based on the phase difference has superior performance than FFT-based frequency offset estimation. In AWGN channel, when the SNR is greater than-3dB, estimation error of frequency offset estimation based on phase difference is close to the CRLB. In fading channels, frequency offset estimation error occurs leveling due to the influence of the Doppler spread.