Dfh System Harq Key Technology Research

In recent years, Differential Frequency Hopping (DFH) communications develop very rapidly, and play an important role in military communications. The CHESS system developed successfully make people to shift their research field to DFH communications, and once again see the advantages and prospects of short-wave communications (SC).Currently there are a large number of research on performance of DFH system, but few studies on the error control of DFH system. Hybrid automatic retransmission request (HARQ) is an important error control technology that guarantee communication systems reliable, high speed and efficient. Therefore this paper mainly focuses on the HARQ of DFH system. The main content as followsAt first, describes the basic principles and development of DFH communication systems, and the basic model of the HARQ based on DFH system. And the package combining technology is applied to the DFH system, detailedly explain the basic principles of package combining technology and the system block diagram of DFH package combining HARQ system.Secondly, the performance of the DFH package combining HARQ system was analyzed, and analyze the bit error rate, frame error rate, the average retransmission times, and data through rate of the package combining HARQ system, and obtained the corresponding theoretical upper bound formula of each of them. Theoretical calculation and simulation show that the theoretical analysis is correct. The package combining HARQ system has lower average number of retransmission and package error rate than no package combining HARQ, thus greatly improve the channel utilization rate and data throughput of DFH system.Finally, just using package combining to improve the performance of DFHsystem is not enough. Then introduce adaptive modulation and coding (AMC), adaptive frame length (AFL), speed adaptive (SA) key technologies improve the package combining HARQ system. And elaborated the principle of AMC, ALF and SA key technologies in more, described the corresponding algorithms in detail, and analyzed formulas of optimal frame length and throughput of DFH system. Furthermore made a lot of simulation experiments. The conclusion shows that those key technologies can further improve the performance and efficiency of DFH system. At last this paper did some exploratory research on cross-layer HARQ.