VDES System Design And Research On Algorithm Improvement Of Multiple Access Technology

In order to solve the problem of channel congestion in automatic identification system(AIS),the concept of very high frequency data exchange system(vdes)is proposed by international maritime organizations such as ITU,IMO and IALA.Every country in the world has done a lot of research and Discussion on the concept and design of vdes system since 2013.This paper mainly focuses on the design of vdes system and the algorithm of multiple access technology.On the basis of its predecessor automatic identification system(AIS),VHF data exchange system(vdes)refines various services,including dividing special application information(ASM)separately and adding some channels to meet the function realization of VHF data exchange.This paper focuses on the design of vdes system and the improvement of its multiple access algorithmFirst of all,the related theories and technologies involved in this paper are introduced.It includes channel frequency,channel partition and power of automatic identification system,special application information and VHF data exchange.At the same time,the software radio used in the system is analyzed and simulated.Secondly,combined with software radio,the overall block diagram of vdes system is designed.On this basis,around the parameters of related protocols,the paper proposes the specifications of VHF data exchange system.In the hardware design of the system,the RF transceiver link,low noise amplifier,filter and power supply of the vdes system are designed.The superheterodyne structure is used in the RF link.The reliability and maintainability of the system are fully considered in the design.Thirdly,an improved algorithm of multiple access technology is proposed to solve the problem of slot reservation conflict in the actual communication process.In this part,the conflict model of slot reservation is built and analyzed.Then,aiming at the shortcomings of the current slot reservation algorithm,an improved reservation algorithm is proposed,and relevant simulation is carried out to verify that its performance is better than the current multiple access technology algorithm.Finally,the VHF data exchange system is implemented and tested.After the completion of RF transceiver link,power supply and digital processing,the VHF data exchange system adds corresponding external modules,including power supply module and antenna module.After the implementation of VHF data exchange system,the test content is selected from the test principle of mobile communication system,which is mainly divided into index test and function test.The index test is mainly combined with the technical index of VHF data exchange system.Functional test,including Ping test,information and file transfer between prototypes.The test results demonstrate the feasibility of VHF data exchange system implemented by software radio.