The Design And Implementation Of Simulation Source And Turbo Code Based On VDES

The first generation of ship navigation system AIS(Automatic Identification System),which has been widely used in the global scope,has become an important tool for maritime communication,ship navigation safety and marine traffic management after many years of development.In recent years,with the increasing demand for maritime communications,the demand for communication between ship and shore link,ship and ship link is increasing.More and more devices are connected to the AIS system,which results in the initial design of AIS system will not be unable to meet the demand of data exchange.In order to alleviate the communication pressure of the AIS system,IALA recommends that the VDES(VHF Date Exchange System)system be built around the world.The VDES system will provide more capacity and faster data exchange capacity for the global maritime equipment at the very high frequency section of the sea,so as to make technical reserves for future e-navigation.In this paper,through the study of key technologies related to VDES,A VDES simulation source structure is designed,and the scheme of generating simulation source data in each link of VDES is given.The general Turbo coding and decoding structure in VDES is designed and implemented,and the application scheme of Turbo code in each link of VDES is given.The performance of Turbo codes in each link of VDES is simulated and verified.The main contents are as follows:First,the related specifications and modulation modes of VDES system,access algorithms,ship distribution and other key technologies related to VDES are studied in detail.Second,the frame structure of ASM,VDE-terrestrial and VDE-satellite uplink and downlink in VDES system are studied,and a VDES simulation source structure is designed.The scheme of generating simulation source data in each link of VDES is given.The simulation source data generation program of each link's simulation source is programmed.Then,the encoding and decoding technology of Turbo code is studied in detail.A general Turbo code encoding and decoding module in VDES is designed and implemented.The performance verification scheme of Turbo code in each link of VDES is given.The coding and decoding program of Turbo code based on MATLAB programming in each link is realized.The bit error rate performance of Turbo code on ASM,VDE-terrestrial and VDE-satellite uplink and downlink is simulated.Finally,simulation Turbo code in each link of the VDES are analyzed.The BER performance of Turbo codes under different coding efficiency of ASM is analyzed,and the BER and BLER(block error rate)performance of Turbo in different bandwidth and modulation mode of VDE-terrestrial is compared and analyzed.The BER performance of Turbo code under different modulation modes in VDE-satellite downlink and uplink is analyzed.