Transmission time difference measurement method and system
First Claim
1. A transmission time difference measurement method in a system having a terminal, two or more base stations that each operate asynchronously, and a control device for controlling the terminal and each of the base stations, said method calculating transmission time differences of signals in each of said base stations and comprising steps wherein:
- when said terminal is able to simultaneously receive signals from each of said base stations, each of said base stations uses a round trip time measurement function to measure the round trip times of signals to and from said terminal;
said terminal uses a turn-around time measurement function to measure, for each of said base stations, the turn-around time from the reception of a signal from the base station until the transmission of a signal to that base station;
said terminal uses an arrival time difference measurement function to measure the arrival time difference, which is the difference between the times that signals arrive from each of said base stations; and
said control device finds the difference in transmission times of signals in each of said base stations based on;
the difference of propagation times between said terminal and each of said base stations that is calculated by subtracting the turn-around time that is measured in said terminal from the round trip time that is measured in each of said base stations, and the arrival time difference that is measured in said terminal; and
uses a storage function to store the calculated transmission time differences in association with the calculation times at which the transmission time differences were calculated.
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Accused Products
Abstract
The propagation time (1605) of signals between a terminal (1304) and a base station (1302) is calculated from the round-trip time (1601) of signals between the terminal (1304) and the base station (1302) and the turn-around time (1603) from the reception by terminal (1304) of a signal from base station (1302) until the transmission of the signal to the base station (1302). The propagation time (1606) of signals between the terminal (1304) and another base station (1303) is similarly calculated. The difference between the propagation times (1605 and 1606) and the arrival time difference (1607) that is calculated in the terminal (1304) are then compared to calculate the transmission time difference (1608) between the base stations (1302 and 1303).
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Citations
46 Claims
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1. A transmission time difference measurement method in a system having a terminal, two or more base stations that each operate asynchronously, and a control device for controlling the terminal and each of the base stations, said method calculating transmission time differences of signals in each of said base stations and comprising steps wherein:
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when said terminal is able to simultaneously receive signals from each of said base stations, each of said base stations uses a round trip time measurement function to measure the round trip times of signals to and from said terminal;
said terminal uses a turn-around time measurement function to measure, for each of said base stations, the turn-around time from the reception of a signal from the base station until the transmission of a signal to that base station;
said terminal uses an arrival time difference measurement function to measure the arrival time difference, which is the difference between the times that signals arrive from each of said base stations; and
said control device finds the difference in transmission times of signals in each of said base stations based on;
the difference of propagation times between said terminal and each of said base stations that is calculated by subtracting the turn-around time that is measured in said terminal from the round trip time that is measured in each of said base stations, and the arrival time difference that is measured in said terminal; and
uses a storage function to store the calculated transmission time differences in association with the calculation times at which the transmission time differences were calculated. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. The transmission time difference measurement method in a system having a terminal, two or more base stations that each operate asynchronously, and a control device for controlling the terminal and each of the base stations, said method calculating the differences in transmission times of signals in each of said base stations and comprising steps wherein:
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when said terminal is able to simultaneously receive signals from each of said base stations, said terminal uses an arrival time difference measurement function to measure the arrival time difference, which is the difference between the times that signals arrive from each of said base stations, and, using a GPS positioning function, uses signals from a GPS satellite to specify the geographical location of said terminal; and
said control device calculates the distances between said terminal and each of said base stations based on the geographical location of said terminal and the geographical locations of each of said base stations that have been measured by said terminal, finds the transmission time differences of each of said base stations based on the propagation time differences that are calculated by diving the differences between the calculated distances by the speed of light and the arrival time differences that are measured at said terminal, and uses the storage function to store the transmission time differences that have been calculated in associated with the calculation time at which the transmission time differences were calculated. - View Dependent Claims (19, 20, 21, 22, 23)
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24. A transmission time difference measurement system comprising a terminal, two or more base stations that each operate asynchronously, and a control device for controlling said terminal and each of said base stations, said system calculating the transmission time differences of signals in each of said base stations;
- wherein;
said control device includes;
a measurement request means for issuing requests for measurement to said terminal and said base stations; and
storage means for storing the transmission time differences of signals of said base stations in association with calculation times at which said transmission time differences have been calculated;
each of said base stations includes a round trip time measurement means for, upon receiving a measurement request that said control device has transmitted using said measurement request means, measuring the round trip times of signals transmitted to and from said terminal; and
said terminal includes;
a turn-around time measurement means for, upon receiving a measurement request that said control device has transmitted using said measurement request means, measuring the turn-around time for receiving signals from said base stations until transmitting the signals to said base stations; and
an arrival time difference measurement means for measuring the arrival time difference, which is the difference between the times at which signals from at least two base stations arrive;
and wherein, when said terminal is able to simultaneously receive signals from each of said base stations;
each of said base stations carries out a process of using said round trip time measurement means to measure each of the round trip times;
said terminal carries out processes of using said turn-around time measurement means to measure turn-around times for each of said base stations and of using said arrival time difference measurement means to measure arrival time differences; and
said control device carries out processes of;
finding the transmission time differences of signals in each of said base stations based on the propagation time differences between said terminal and each of said base stations that are calculated by subtracting the turn-around time that is measured in said terminal from the round trip times that have been measured in each of said base stations, and the arrival time difference that is measured in said terminal; and
storing in said storage means the transmission time differences that have been calculated. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
- wherein;
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41. The transmission time difference measurement system comprising a terminal, two or more base stations that each operate asynchronously, and a control device for controlling said terminal and each of said base stations, said system calculating the transmission time differences of signals in each of said base stations;
- wherein;
said control device includes;
a measurement request means for issuing requests for measurement to said terminal; and
storage means for storing the transmission time differences of signals of said base stations in association with calculation times at which said transmission time differences have been calculated;
said terminal includes an arrival time difference measurement means for, upon receiving a measurement request that said control device has transmitted using said measurement request means, measuring the arrival time difference, which is the difference between the times at which signals from at least two base stations arrive; and
at least one of said terminal and said control device includes a GPS positioning means for using signals from a GPS satellite to specify the geographical location of terminals;
and wherein, when said terminal is able to simultaneously receive signals from each of said base stations;
said terminal carries out a process of using said arrival time difference measurement means to measure the arrival time difference;
at least one of said terminal and said control device carries out a process of using said GPS positioning means to specify the geographical location of terminals; and
said control device carries out processes of;
calculating the distances between said terminal and each of said base stations based on the geographical location of said terminal and the geographical locations of each of said base stations that have been measured, finds the transmission time differences of each of said base stations based on the propagation time difference that is calculated by dividing the differences in calculated distances by the speed of light and the arrival time difference that has been measured at said terminal, and storing the transmission time differences that have been calculated in said storage means. - View Dependent Claims (42, 43, 44, 45, 46)
- wherein;
Specification