.ffh / Mfsk System Interference Suppression Algorithm Research

Wireless communications, as an important communication resorts for military campaign are highly vulnerable to hostile electromagnetic interferences due to we have shared the same transmission channel with enemys. In order to prevent the information is intercepted or the communication process is disturbed or even interrupted in the military communications, we need to pay more efforts to study the anti-jamming technologies in the military communications. Anti-jamming technologies are developed to ensure communication system work under the hostile electromagnetic interferences safe and sound, and are achieved by the cost of lower utilization rate of bandwidth, reducing the detected and intercepted probability of signal. Frequency hopping communication system with these characteristics has been widely used in military wireless communication fields. In this dissertation, we analyzed the anti-jamming mechanism of hopping communication system and studied the anti-jamming technologies at the receiver end under the condition of hostile electromagnetic interferences.Firstly, we introduced the research background and significance of frequency-hopping communication system, and summarized current situation of jamming suppression strategy, and analyzed the dominating types of jamming. At the end of chapter one, we have listed the main contents of this dissertation.In chapter two, we elaborated the composition of FFH/MFSK and analyzed the BER expressions under different conditions.In chapter three, we summarized kinds of diversity-combining algorithms and proposed an improved product-combining algorithm due to the deficiency of traditional product-combining algorithm. Moreover, we showed its theoretical basis and simulation results.We proposed a noval diversity-combining anti-jamming algorithm in chapter four. This algorithm takes the advantages of product combining and self-normalizing combining and clipper combining schemes to further suppress the jamming signal. From the results of simulation, we got that this algorithm has better anti-jamming performance than traditional methods.In chapter five, we studied the BER performance of product-combining algorithm and maximum likelihood algorithm under the worst case PBNJ over frequency-selective fading channel.Finally, we summarized the work of this dissertation and showed the research results.In order to consolidate next work,we proposed several research interests with the help of other scholars.