METHOD FOR MEDIA ACCESS CONTROL OF VEHICULAR AD HOC NETWORK USING VARIABLE LENGTH FRAME AND ROAD SIDE UNIT USING THE SAME

摘要

A method for media access control in a vehicular ad hoc network using a variable length frame comprises the following steps of: obtaining, by a roadside unit in a vehicular ad hoc network, the number of estimated vehicle nodes based on an estimated unused probability obtained by estimating an unused probability as the ratio of unused slots to the length of a contention period during a previous frame; determining a greater value among a value calculated by subtracting the number of successful transmission slots in a contention period during the previous frame from the number of estimated vehicle nodes and the number of minimum contention period service slots as the length of an estimated contention period in a current frame; determining the number of estimated successful transmission nodes in the previous frame obtained by adding the number of successful transmission slots in a contention free period in the previous frame and the number of successful transmission slots in the contention period in the previous frame as the length of an estimated contention free period in the current frame; and setting the contention period and the contention free period in the current frame each according to the estimated contention free period length and the estimated contention period length in the current frame.