Research And Simulation Of Uplink And Downlink Channel Estimation In VDE-SAT

As an ocean VHF broadcasting system,the ship automatic identification system(AIS)provides the service of broadcasting navigation and the ship's own parameter information for the ships on the sea.It plays a very important role in ensuring the safety of navigation and improving the management of maritime traffic.However,as amount of ships equipped with AIS continue to increase,AIS appears to be a problem of performance degradation due to link overloads in some densely populated areas of ships.Therefore,it is urgent to upgrade AIS to VHF data exchange system VDES.VDES not only fully compatible with the AIS,but also expanded the special application packet ASM and broadband VHF data exchange VDE function.VDE-SAT is the data exchange system between VDE satellite and ground.Large capacity data exchange requirements and satellite time-varying channel characteristics make it necessary that VDE-SAT need to use appropriate and feasible channel estimation techniques to improve the communication quality of the system.In this paper,we study the channel estimation techniques for VDE-SAT uplink and downlink,and the main work is as follows:(1)the channel parameters and models of VDE-SAT satellite are discussed.The key technologies of VDE-SAT anti-jamming fading modulation and demodulation,channel coding,frame synchronization and channel estimation are introduced.(2)a pilot estimation algorithm of linear interpolation based on Rician channel model is proposed,and the performance of this algorithm is simulated,and the simulation results of other polynomial interpolation algorithms are compared and analyzed.(3)according to the estimation of spread spectrum technology to use algorithm and VDE-SAT channel linear interpolation VDE-SAT is proposed,combined with auxiliary pilot and direct spread spectrum estimation method of minimum two to reduce the Gauss effect of noise on the channel estimation,in order to improve the accuracy of channel estimation.Linear interpolation channel estimation technology can significantly reduce the impact of channel fading on the signal,reduce the bit error rate of the system,and improve the quality of VDE-SAT communication.