function generates the downlink data message through LTE method---------------------------------------------------------------------------------------

function generates the downlink data message through SAT method---------------------------------------------------------------------------------------

function generates the downlink data message through UAV method---------------------------------------------------------------------------------------

function generates the uplink control message from each vehicle---------------------------------------------------------------------------------------

function indicates that the vehicle received one downlink data message through LTE method-------------------------------------------------------------

function indicates that the vehicle received one downlink data message through SAT method-------------------------------------------------------------

function indicates that the vehicle received one downlink data message through UAV method-------------------------------------------------------------

function indicates that the server received one uplink control message through LTE method-------------------------------------------------------------

function indicates that the server received one uplink control message through SAT method-------------------------------------------------------------

function indicates that the server received one uplink control message through UAV method-------------------------------------------------------------

the main function-------------------------------------------------------------------------------------------------------------------------------------