Research On The HARQⅡ Link Transmission Protocal Based On Bitmap Feedback In Meteor Burst Communication System

This topic comes from the key funded project of the ISN State Key Laboratory.Meteor burst communication channel has characteristics, such as discontinuousappearance, instability, strong anti-jamming capability and confidentiality. Based onthese channel characteristics, the meteor burst communication system has been widelyapplied in military communication, but it is still with low throughput due to the channelcharacteristics. In order to make the emergency, communication system can overcomethe bottleneck to make popular advantage in military operations, considering the systemcomplexity, this article proposes a link transport protocol combining adaptivemodulation to improve the throughput based on the system.Firstly, This paper discusses the meteor burst communication channel model,confirms that the channel has the exponent decline and discontinuous appearance.Because of the changeable channel, this paper proposes a Hybrid Automatic RepeatRequest (HARQ) II link layer transport protocol based on feedback bitmap. Amongthem, the bitmap feedback technology means that a certain buffer must be found in boththe sender and receiver to make the multi-channel data organizing frame and receivingfeedback independently, so that we can ensure that the data frames can be sent in time.HARQII protocol is upgrade version of the simple ARQ. The protocol rules that the dataframe should carry on information bits at full rate for the first time, then the parity bitsif necessary next time, which increases the throughput comparing with HARQI protocol.The Forward Error Correction(FEC) technology in the protocol uses the code word,Quasi Cyclic-Low Density Parity Check (QC-LDPC)who has strong ability of errorcorrection and simple decoding method. Later, this article introduces the adaptivemodulation technology. The technology can adapt well to the channel fading and makesfull use of the channel capacity. This article also proves how to determine the switchingthresholds. Finally, this paper gives the simulation of the protocol mentioned above. Inthis paper, the throughput which we get from the simulation for a period of time in therange of0to25dB SNR shows that the throughput of HARQII protocol combining theadaptive modulation based on bitmap feedback is always greater than that whencombining the single modulation. This paper also gives the comparison of thethroughput between HARQII protocol and HARQI protocol, and HARQII protocol isproved better.