Mobile object information sharing system

• US 8,111,680 B2
• Filed: 04/07/2005
• Issued: 02/07/2012
• Est. Priority Date: 04/07/2005
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Ijiri, Masao
• Primary Examiner(s): Chang, Kent
• Assistant Examiner(s): Elhag, Magdi
• Application Number:
  US11/659,692
• Publication Number:
  US 20080043715A1
• Time in Patent Office: 2,497 Days
• Field of Search: 370345-350, 370/294, 370/326, 370/313, 370/337, 370431-433, 370/437, 370458-459, 455/440, 455/441, 4554561-4566, 455/457, 455/458, 455/569.2, 455/404.2, 701200-216
• US Class Current: 370/345
• CPC Class Codes: G01S 19/42 Determining position
• CPC Class Codes: G01S 5/0027 of actual mobile position, i.e. position determined on mobile

Abstract

In a system where mobile stations use one frequency to transmit/receive and share position information data, synchronization has been made in a shared time resulting from GPS and the mobile stations transmit the data at mutually different timings that are predetermined, whereby overlapping of the transmissions is avoided. However, the transmission period of a station cannot be changed even if that station wants to change its transmission period. Transmission period determining units are disposed which determine transmission periods on the basis of the moving speeds of mobile stations. The mobile stations are time-synchronized by GPS. After the time synchronization, fundamental transmission periods comprising plural time slots are disposed. Transmission is done just in one time slot within one fundamental transmission period normally, and the number of transmissions is increased to two times or three times within one fundamental transmission period when the period is to be shortened.

Claims

1. A mobile object information sharing system comprising a plurality of mobile stations, wherein each mobile station includes:

a radio device for communicating mutually at one radio frequency;

a GPS receiver that obtains, by GPS radio waves, at least position information and moving speed information of its own station and shared time information;

a time division synchronous radio modem device that synchronizes mutually among the plurality of mobile stations using the shared time information, after this time synchronization, sets a fundamental transmission period by arranging continuously a plurality of transmission slots having a predetermined time width, verifies the use status of the plurality of transmission slots during the fundamental transmission period, transmits the position information of its own station to the radio device in an optional period of the plurality of transmission slots, and receives the position information of other mobile stations;

a transmission period determining unit for determining the optional period using the moving speed of the mobile station; and

an operation unit that determines a transmission timing among the plurality of transmission slots based on the optional period determined by the transmission period determining unit and transmits the position information of its own station, and

the mobile station further includes a movement monitoring unit that monitors the movement trajectory of its own station and, when the moving direction has changed equal to or greater than a predetermined angle within a predetermined time, stores the position and the time, and

when the position and the time is stored in the movement monitoring unit, the mobile station transmits the information of the position and the time at a timing of the position information of its own station immediately after the time.

2. A mobile object information sharing system comprising a base station and a plurality of mobile stations wherein each mobile station includes:

a radio device for communicating mutually at one radio frequency;

a GPS receiver that obtains, by GPS radio waves, at least position information and moving speed information of its own station and shared time information;

a time division synchronous radio modem device that synchronizes mutually among the plurality of mobile stations using the shared time information, after this time synchronization, sets a fundamental transmission period by arranging continuously a plurality of transmission slots with a predetermined time width, verifies the use status of the plurality of transmission slots during the fundamental transmission period, transmits the position information of its own station to the radio device in an optional period of the plurality of transmission slots, and receives the position information of other mobile stations, wherein the optional period is a divisional period of the fundamental transmission period;

a transmission period determining unit for determining the optional period using the moving speed of the mobile station; and

an operation unit that determines a transmission timing among the plurality of transmission slots based on the optional period determined by the transmission period determining unit and transmits the position information of its own station, and

the mobile further includes a movement monitoring unit that monitors the movement trajectory of its own station and, when the moving direction has changed equal to or greater than a predetermined angle within a predetermined time, stores the position and the time, and

when the position and the time is stored in the movement monitoring unit, the mobile station transmits the information of the position and the time at a timing of the position information of its own station immediately after the time.