Patent ID: 6185429
Filing Date: 2001-02-06
Classification: H04B

Abstract:
A communication system comprising:a base site that transmits a time synchronization calibration request;a communication unit including:a receiver to receive the time synchronization calibration request; anda transmitter to transmit time difference of arrival information to a controller;at least a second base site to transmit a radio frequency signal to the communication unit and to receive a radio frequency signal from the communication unit;a location-determining device to determine a location of the base site and a location of the at least a second base site; anda controller to determine the location of the communication unit and to calculate time synchronization error for the base site, wherein the controller calculates the time synchronization error according to the following equations:Expected TDOA12-(D1-D2)/(speed of light)Time synchronization error=Expected TDOA12-TDOA12wherein:D1 is a distance from the location of the communication unit to the location of the at least a second base site;D2 is a distance from the location of the communication unit to the location of the base site;Expected TDOA12 is an expected time difference of arrival for signals received by the communication unit from the base site and the at least a second base site;TDOA12 is a measured time difference of arrival for signals transmitted to the communication unit by the base site and by the at cast a second base site; andTime synchronization error is an amount of time by which a timing reference of the base site is offset from a timing reference of the at least a second base site.