Research And Implementation On Key Technologies For FH Communication System Based On Cognition

As one of the main methods in modern wireless communication field,frequency hopping(FH)communication has many advantages,such as strong anti-interference ability,low interception probability,excellent ability of multiple access networking,being compatible with narrow band communication systems easily and so on.However,with the rapid development of modern informatization technology,many challenges make that FH communication technology doesn't satisfy the requirement for high efficiency and reliable data transmission,such as growing tense spectrum resource,continuous upgrading of complicated interference,and complicated variable communication link environment.Moreover,the performance of traditional FH communication system reaches the bottleneck.Therefore,in order to improve the comprehensive performance of FH communication,it needs to adjust the system parameters dynamically and adaptively which is changed by the electromagnetic environment for FH communication system under the environment of limited bandwidths.And then the communication system can work in the optimal state dynamically.Based on the requirement for validity and reliability of FH communication system,this paper has designed the cognitive FH communication system which brings the spectrum perception technology of cognitive radio into the traditional FH communication.This system can adjust the parameters dynamically.Moreover,the key technologies of FH sequence generation and FH synchronization in this system have been studied and implemented in this paper.The main work contains following several aspects:1.This paper introduces the challenges that the existing traditional FH communication technology has to face with,and expound the development background,operating principle,and key technology in cognitive FH communication system.The main architecture design of the system is also given.2.Aiming at the requirement for changing the parameters adaptively and dynamically in the cognitive FH communication system which works in the complex and variable environment,this paper has studied the cognitive FH sequence which is generated by pseudo-mapping algorithm from the basic FH sequence based on the 3DES block encryption ciphers.Then we can get the FH sequence that its parameters change dynamically.From the simulation verification and data analysis,we can find the good comprehensive performance of the scheme what we have designed.Therefore,it can be used in the cognitive FH communication system.3.The advantages and disadvantages of existing FH synchronization technology are analyzed.Then a differential scanning FH synchronization scheme which based on time of day(TOD)information is researched.Moreover,the detailed introduction and design for synchronization scheme is also given.By the simulation verification and data analysis,this scheme shows the good reliability and stability.Therefore,it can be used in cognitive FH communication system.4.This paper designs the FH overall controlling scheme for cognitive FH communication system.Moreover,the hardware description language VHDL is used to design the corresponding digital circuit for controlling scheme,then the whole system is debugged and verified based on experimental platform.The result shows that the communication system owns excellent performance and can adjust the parameters dynamically according to the spectrum environment in the communication bandwidth and transmit data reliably.