Abstract: According to the precision of the GPS communication system on the close cars,this paper designed a close high-precision positioning auxiliary system,and implemented an efficient real-time communication around the cars．Ultrasonic technology was used to get the distance between cars,and calculate the relative angle．This data was binded with the device communication address through effective communication initialization algorithm and dynamic update algorithm,generating a complete node information．Node informations are processed to build 2D plans about the environment around cars in real-time,in order to achieve the purpose of the selective communication between close cars.

Key words: High-precision positioning,Ultrasonic sensor,Initialization algorithm,Real-time communication