Slot Allocation Technology Based On VDE-SAT Bulletin Board

As a new generation of maritime digital communication system,VHF Data Exchange System(VDES)provides a new means for maritime users to communicate with large bandwidth,high speed and long distance.The VDE Satellite(VDE-SAT)subsystem is the last component to realize the full operational capability of VDES.One of its goals is to provide high-speed,global communication services for ship stations.However,the complex satellite network cost and limited link resources make VDE-SAT resource management face a huge challenge.Therefore,slot resource management of VDE-SAT has become one of the key issues in VDESAT research area.This thesis studies the slot allocation technology based on the VDE-SAT Bulletin Board,which lays a foundation for the research on VDE-SAT resource management and provides a reference for the formulation of relevant standards and guidelines.Firstly,this thesis investigated the work flow and technical characteristics of VDE-SAT and establishes a systematic theoretical research background.Secondly,for the situation that there is no explicit VDE-SAT slot allocation algorithm in the VDES technical characteristics standard ITU-R M.2092-1,this thesis selects the multi-knapsack algorithm as the solution direction of slot allocation for VDE-SAT subsystem,and proposes a decision analysis knapsack(DAK)slot allocation algorithm with comprehensive consideration of network efficiency and service quality.This algorithm preprocesses packets before executing the multi-packet algorithm,calculates the dynamic priority of user queues using decision analysis theory,and executes the multi-knapsack algorithm to allocate slots for packets according to this decision analysis result.The experimental results show that,compared with the basic knapsack algorithm,the DAK slot allocation algorithm significantly reduces the queue length and increases the transmission value,that is,the communication efficiency and service quality are improved.And compared with the First Come First Served(FCFS)algorithm commonly used in wireless communication networks,it is more suitable for the VDE-SAT subsystem.In addition,according to the work flow of VDE-SAT,the system performance is optimized only when the slot allocation algorithm works in coordination with the Bulletin Board.Therefore,this thesis gives a configuration model for VDE-SAT Bulletin Board,and on this basis,designs a provisioning strategy for VDE-SAT Bulletin Board.Subsequently,the Bulletin Board provisioning strategy works in coordination with the DAK slot allocation algorithm,which solves the problem that the current default Bulletin Board cannot provide optimal system performance for various scenarios.The experimental results show that the coordination of the slot allocation algorithm and the Bulletin Board provisioning strategy can improve the system’s packet delivery rate by 10%.In the process of the above research,this thesis builds a system model of VDE-SAT based on OMNe T++ development environment,simulates the data exchange process between ship and satellite,and provides a reliable and effective experimental platform for the research of VDE-SAT slot allocation technology.This system model has the function of Bulletin Board provisioning and slot allocation,and it uses the hierarchical structure of ship nodes and satellite nodes to realize the interaction of data flow.In the simulation process,the effectiveness of the slot allocation technology based on VDE-SAT Bulletin Board is verified by collecting and analyzing the simulation results.