Design And Implementation Of A Data Link Layer Protocol For Hf Communication

HF communication is a means of long-distance wireless communication.Because of the characteristics of anti-destruction,low cost and non-repeater,HF communication plays an important role in the military communication.With the growing demands from users,the laboratory developed the third generation “HF frequency selection and link establishment system” on the basis of the previous research on HF communication.“HF frequency selection and link establishment system” mainly studied the protocol of U.S.MIL-STD-188-141 B,used the short wave adaptive technique,and improved the reliability of link establishment and the efficiency of data transmission.The data link layer protocol of the system is studied in this paper,and the main works are as follows:1.By analyzing the research target of “HF frequency selection and link establishment system”,the data unit of link establishment protocol is designed,and the existing data unit of data transmission protocol is improved.2.Considering the various waiting time of channel calling for short-wave transmitters,we designed different link establishment schemes,achieving the function of channel detection,link establishment and frequency update.3.Having studied the existing data transmission protocol,we improved the breakpoint retransmission protocol.Through deeply studying the technique of adaptive rate changing,a new adaptive rate changing method based on the error feedback is proposed.The results of simulation experiment indicate that the adaptive rate changing method based on error feedback is superior to the existing rate changing method of the laboratory.The adaptive rate changing method based on error feedback is capable of selecting the better data transmission rate based on the change of channel,thus improving the throughput of data transmission.4.Through programming the data link layer software,the data link layer protocol designed in this paper is realized.The function of self-check is added into the software,which can preliminarily determine the location of fault when it occurs.5.Through setting up the indoor test platform,the function and performance of link establishment protocol and data transmission protocol are tested.The test results manifest that the designed data link layer protocols can achieve the function of channel detection,link establishment,frequency update,and data transmission.The test results are consistent with the expected results when designing.