COMMUNICATION FRAME FORMING METHOD IN COMMUNICATION SYSTEM BETWEEN ROAD AND VEHICLE

摘要

PROBLEM TO BE SOLVED: To prevent communication impossibility between road and vehicle due to the overlap of control messages at all times from both base stations in a mobile station existing for a plurality of communication zones. SOLUTION: The base stations set the number of data slots 3 included in respective communication frames 1 while it is changed at random. Even if control packets 4a1 and 4b1 by a common radio frequency from the base stations collide, communication frame lengths transmitted from the base stations differ. Thus, control packets 4a2 and 4b2 sent fro the base stations next do not collide. Consequently, the mobile station existing in the overlap area of the communication zones of the different base stations can normally receive the packets since they do not collide.