Research On The Channel Coding And Automatic Repeat ReQuest In Advanced Orbiting Systems

In order to deal with the challenge of space technology proposed by the diversityof the space missions and promote exchanges and cooperation between countries, theConsultative Committee for Space Data Systems (CCSDS) developed the AdvancedOrbiting System (AOS) in1989. AOS make a series of criterions and standards ofvarious space technologies to meet the need of peaceful use of space resources and thestrengthening international cooperation. In recent years, AOS technology is playing anincreasingly prominent role in the satellite communication technologies.At first, the basic contents of the space packet protocol, space data link protocoland telemetry and channel coding protocol are analyzed, including the introduction ofthe major service, the common data unit format and the channel coding schemes.Secondly, the basic principles of the major error control technology in satellitecommunications are briefly introduced, and the characteristics of low-orbiting satellitescommunications are analyzed and a model of low-orbiting satellite channel isestablished. Then the basic encoding and decoding principles of convolutional codeand Turbo code decoding specified in AOS are introduced. An AOS simulation systemmodel with channel coding is established and convolutional code and Turbo code areused in the model. The AOS system performances of Turbo code in differentparameters are compared. Experiments show that the increasing of connection vectorlength, interleave length and iteration times will correspondingly improve theperformance of Turbo code. The performances of AOS system respectively usingconvolutional code and Turbo code with the same parameters are also compared, andthe performance of AOS using Turbo code is much better than that of AOS usingconvolutional code.To improve the transmission reliability of important satellite data, an improvedtransmission method of AOS is proposed, in which Hybrid Automatic Repeat reQuest (HARQ) technologies are introduced. The performances of commonly used ARQschemes are compared, and the selective repeat ARQ scheme is chosen for thecombination with channel coding to form HARQ. An AOS simulation model in whichHARQ technology is introduced is also established, and the performance of AOS usingdifferent HARQ schemes including HARQ-I, HARQ-II, chase HARO-III and IRHARQ-III are studied from four aspects: the bit error rate, frame error rate, averagetransmission times and throughput. The research results show that the proposed AOStransmission method with any HARQ scheme of the four kinds mentioned aboveperforms better than the common AOS transmission method without HARQtechnology in all of the four aspects, which proves the practicability of our proposedmethod. Further research shows that using whether convolutional code or Turbo codein HARQ, the performance of AOS using IR HARQ-III scheme is the better than thatof AOS using any of the other three HARQ schemes. It is also shown that when usingIR HARQ-III scheme, the performance of AOS using Turbo code is much better thanthat of AOS using convolutional code.