Patent ID: 6493562
Filing Date: 2002-12-10
Classification: G07B

Abstract:
A communication system comprising:a stationary communication device placed at a predetermined position and forming a communication area covering vehicles traveling on a road; and at least one vehicular communication device mounted on a vehicle for communicating with said stationary communication device when said vehicle enters said communication area; wherein said stationary communication device allocates an individual communication slot to each vehicular communication device in the communication area equivalent to a width of said road to perform one-to-one communication, divides sound guidance data into a plurality of sound data blocks of predetermined communication frames, assigns sequential numbers for each respective divided sound data block, and transmits said divided sound data blocks along with said assigned sequential numbers successively using said individual communication slots; wherein said at least one vehicular communication device receives said divided sound data blocks and said assigned sequential numbers transmitted from said stationary communication device using said individual communication slots and, after accomplishing reception of all of said divided sound data blocks and said assigned sequential numbers, checks any failure in the data communication by checking whether any assigned sequential number of said divided sound data blocks is missing; and wherein only a vehicular communication device with a missing assigned sequential number of a sound data block requests said stationary communication device to retransmit only the specific sound data block that corresponds to said missing assigned sequential number when said check for missing assigned sequential numbers reveals said vehicular communication device failed to receive said specific sound data block, and thereafter issues a sound guidance using the received sound data blocks including said retransmitted specific sound data block.