Simulation Research Of Adaptive Frequency Hopping Communication System

Adaptive frequency hopping (AFH) is a new technology that developed in recent ten years, that integrates adaptive frequency control with adaptive power control based on automatic link quality analysis (LQA). The system can keep long term high quality communication in non-interfere channels with minimum transmitting power and low probability of intercept by getting over the "blind hopping" weakness of conventional frequency hopping communication system. The HF fast adaptive frequency hopping communication is a new developing direction in the field of military anti-jamming communication foV tactics application.In this thesis, a HF fast adaptive frequency hopping communication system for fulfilling the demand of the performance of anti-jamming and secrecy in military wireless communication field is simulated, and key technologies such as link quality analysis, adaptive frequency control and adaptive power control are researched. First, the simulation system is designed and parameter is determined after the introduction of fundamental principle of frequency hopping and giving the model of adaptive frequency hopping. The performance of FH/BFSK system is analyzed under the several interferences. Then, based on the introduction of content, method and technology of synchronization, the acquisition and tracking is accomplished by matched-filter and single channel loop, respectively. Thus, the basic frequency hopping system is established. And then, a link quality analysis method based on the SNR prediction algorithm is proposed, some problems of it such as the SNR real-time estimation, Kalman prediction, determination of threshold are studied. The generator of adaptive FH pattern is designed. By using it and the result of the LQA, adaptive frequency selection is accomplished. A power control based on SNR and closed loop control is proposed for adaptive power control in AFH in terms of the structure of the system. Finally, the result ofsimulation shows that the selected methods for the system have good performance, and can be used in the fast FH system for accomplishing adaptive control.