Design And Implementation Of Communication Protocal On Cognitive Frequency Hopping System Communications

Frequency hopping communication is a telecommunication method utilizing the synchronized carrier frequency transformation between the transmitting and receiving to transmit information. It performs perfectly in anti-interference and anti-interception. However, with the complicated change of electromagetic channel and the continuous update of interference technology, the conventional frequency hopping communication cannot satisfy the requirement of modern communication, especially the military communication. Hence the cognitive frequency hopping communication is proposed. The cognitive frequency hopping communication technology combines the cognitive wireless technique and frequency hopping technique organically. Through the detecting and analysis of spectrum environment, the search of spectrum hole and available spectrum band for communication, the adaption of frequency hopping radio in complicated electromagnetic environment can be improved, the mutrual interference between radio station can be weakend, the spectrum resources availability can be improved. Hence it has become one of the effective solutions to conventional frequency hopping dilemma currently.In this paper, we do researches on the cognitive frequency hopping system protocals. The multi-link high speed data transmission protocol that is adapted to cognitive frequency hopping system is proposed, with the following aspects principally.(1) Based on the fixed and hopping frequency data communication and spectrum sensing function that the current system should realize, we designed the command frame comprised of parameters like wave pattern, rate, coding, and the information frame carried by user data. Meanwhile, in order to realize the high speed and stable transmission of user data and the continuity and efficiency of bottom data processing, we designed the flow control frame that controls the the data transmission between upper layer and bottom layer.(2) According to the fact that the user data and spectrum sensing information require to transmit through varied communication links, and that the decision parameters of spectrum sensing requires to be transmitted through highly reliable public control links,we established data communication channel, spectrum sensing data channel and sensing result feedback channel between upper layer and bottom layer. We realized the independent transmission of user data and sensing information. And we made the transmitter and receiver change the parameters like communication frequency, modulation schemes, and rate intelligently. Hence the high speed reliable information transmission is realized.(3) In terms of that the communication feedback delay is high while the non-real-time upper layer communicates with the real-time bottom hardware platform in cognitive hopping frequency system, a general flow control mechnism in non-real-time operation system is proposed and improved in this paper. The active-stop flow control mechanism is designed in upper layer, it can save the memory space in bottom FPGA greatly, decrease the response of delay commands, and improve the data transmission efficiency.(4) Based on the multi-link transmission frame design in the cognitive hopping frequency system, we did frame grouping and frame solution with user data in the upper machine software. The transmission and control of the command frame and information frame is realized, the transmission of user data and spectrum sensing data is completed.After the design and realization of the cognitive frequency hopping system telecommunication protocal, we make the test and analysis for the feedback delay that may influence the flow control machanism as well as the telecommunication speed. Further, the coorprative work of the telecommunicaiton frame and cogntive frame is tested through bit error rate test function. Finally, the reliability, validity, and high efficiency are verified through the three aspects above.