Communications: directive radio wave systems and devices (e.g. – Directive – Including a satellite
Reexamination Certificate
2001-12-21
2003-10-21
Phan, Dao (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Directive
Including a satellite
C342S357490
Reexamination Certificate
active
06636176
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a system for determining the position of a mobile communication terminal, and more particularly, to an apparatus for determining the position of the mobile communication terminal, in which a satellite signal and a mobile communication signal are used, and a method therefor.
2. Description of the Background Art
A conventional method for determining the position of a mobile communication terminal (hereinafter, a mobile terminal) is divided into a method, in which a global positioning system (GPS) is used, and a method, in which a mobile communication signal is used. According to the method, in which the GPS is used, the position of the mobile terminal is calculated using a GPS satellite signal. According to the method, in which the mobile communication signal is use, the position of the mobile terminal is calculated by measuring the reception angle and the delay time of a signal delivered by the mobile terminal.
FIG. 1
shows a conventional position determination system, in which the GPS is used.
As shown in
FIG. 1
, the conventional position determination system, in which the GPS is used, includes a mobile terminal
101
, in which a GPS engine
101
a
is loaded, a base station
102
for transmitting data to and receiving data from the mobile terminal
101
, a GPS receiver
105
for receiving the transmission signal of a GPS satellite
104
and outputting the error compensation data of the GPS satellite signal and information related to the GPS satellite
104
such as a satellite number, a satellite orbit, Doppler information, and a navigation message, and a position calculation server
106
for transmitting the error compensation data and the satellite information that are output from the GPS receiver
105
to the mobile terminal
101
and calculating the position of the mobile terminal
101
using the pseudo range transmitted from the mobile terminal
101
through a network
103
.
The operation of the conventional position determination system, in which the GPS is used, of the above structure will now be described with reference to the attached drawings.
The GPS engine
101
a
that is built-in the mobile terminal
101
requests the GPS satellite information to the position calculation server
106
through the base station
102
and the network
103
.
At this time, the GPS receiver
105
connected to the position calculation server
106
receives the transmission signal of the GPS satellite
104
, measures data for correcting the error included in the GPS satellite signal and the GPS satellite information such as a satellite orbit parameter, the Doppler information, and the navigation message, and periodically outputs the data and the GPS satellite information to the position calculation server
106
.
When the GPS satellite information is requested by the GPS engine
101
a
, the position calculation server
106
transmits the GPS satellite information stored in a database (DB) to the GPS engine
101
a
through the network
103
and the base station
102
. The GPS engine
101
a
calculates the pseudo range between the mobile terminal
101
and the GPS satellite using the transmitted GPS satellite information such as a receivable satellite number, the satellite orbit parameter, the Doppler information, and the navigation message, measures the time information of the GPS satellite signal, and transmits the pseudo range and the time information to the position calculation server
106
together with a position calculation request signal.
Therefore, according to the position calculation request of a mobile terminal
301
, the position calculation server
106
corrects the pseudo range using the error correction data stored in the DB and calculates the position of the mobile terminal
101
using a triangular survey.
FIG. 1
shows the conventional position determination system, in which the mobile communication signal is used.
As shown in
FIG. 1
, the conventional position determination system, in which the mobile communication signal is used, includes a plurality of signal measuring apparatuses
202
-
1
installed in a base station
202
, the signal measuring apparatuses
202
-
1
for measuring the reception angle and the delay time of the signal transmitted from a mobile terminal
201
, a mobile communication signal server
204
for storing the reception angle and the delay time of the mobile communication signal transmitted by the signal measuring apparatuses
202
-
1
, and a position calculation server
205
for reading the reception angle and the delay time of the mobile communication signal from the mobile communication signal server
204
according to the request of the mobile terminal
201
, to thus calculate the position of the mobile terminal
201
.
The operation of the conventional position determination system, in which the mobile communication signal is used, of the above structure will now be described.
The signal measuring apparatuses
202
-
1
receive the transmission signal of the mobile terminal
201
, measure the reception angle and the delay time of the transmission signal, and transmit the measured reception angle and delay time together with identifier information and reference time information. At this time, times between the signal measuring apparatuses
202
-
1
must be synchronized.
Therefore, the mobile communication signal server
204
receives the reception angle and the delay time from the signal measuring apparatuses
202
-
1
through a network
203
and stores the reception angle and the delay time by mobile terminals, measuring times, and signal measuring apparatuses (or base stations).
When the position of the mobile terminal
201
requests the position calculation server
205
to calculate the position thereof, the position calculation server
205
obtains the reception angle and the delay time of the mobile communication signal from the mobile communication signal server
204
and calculates the position of the mobile terminal
201
.
In general, according to the conventional position determination method, in which the GPS is used, it is possible to calculate the correct position of the mobile terminal only when four or more GPS satellite signals are received due to a time error during the triangular survey. In the downtown, it is possible to measure only a small number of GPS satellite signals because there exist various elements that deteriorate the visibility of the GPS satellite signal such as skyscrapers. In particular, it is not possible to smoothly receive the GPS satellite signal inside buildings, where the GPS satellite cannot be seen. Therefore, according to the conventional position determination method, in which the GPS is used, the position of the mobile terminal cannot be correctly determined in the downtown or inside the buildings.
According to the conventional position determination method, in which the mobile communication signal is used, it is possible to calculate the correct position only when the reception angle and the delay time of the mobile communication signal are received from three or more signal measuring apparatuses. In the downtown, it is possible to easily receive the mobile communication signal from three or more signal measuring apparatuses because there exist a large number of base stations. However, in a highway and the country, it is not possible to smoothly receive the mobile communication signal because there exist a small number of base stations. Therefore, according to the conventional position determination method, in which the mobile communication signal is used, it is not possible to determine the position of the mobile terminal in the highway and the country.
Also, in the downtown, errors increase in processes of propagating the transmission signal of the mobile communication signal because the transmission signal propagates through multiple paths. Therefore, in the downtown, more errors are found in the conventional position determination method, in which the mobile communication signal is used, than in the position d
Fleshner & Kim LLP
LG Electronics Inc.
Phan Dao
LandOfFree
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