ON-VEHICLE COMMUNICATION EQUIPMENT, ITS ROADSIDE EQUIPMENT, ON-VEHICLE COMMUNICATION LSI, AND ITS ROADSIDE EQUIPMENT LSI

摘要

PROBLEM TO BE SOLVED: To provide a communication apparatus to perform transmission power control which can maintain throughput as well as secure a service area in road-to-vehicle and vehicle-to-vehicle communications accessed by a CSMA/CA method.

SOLUTION: In a communication apparatus, a road information database in which position information and vehicle density information are correlated to each other and a communication control unit are incorporated. The road information database outputs vehicle density information on the basis of position information which is input. The communication control unit controls transmission power on the basis of vehicle density information at its own position which is obtained by using the road information database. Since transmission power control is exercised so as to lower transmission power in an area where the vehicle density is high or raise transmission power in an area where the vehicle density is low without consuming throughput for communication to obtain the vehicle density information, communication with optimum transmission power necessary to secure a service area can be performed while maintaining throughput intact.

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