Source: http://www.google.nl/patents/US20020004398
Timestamp: 2018-01-16 13:21:12
Document Index: 32063694

Matched Legal Cases: ['art 2001', 'art 1999', 'art 2009', 'art 2015', 'art 2014', 'art 2017', 'art 2014', 'art 2017', 'art 2007', 'art 2009', 'art 2011']

Patent US20020004398 - Method of providing location service using CDMA-based cellular phone system ... - Google Patenten
At least three base stations transmit a specific signal pattern at given intervals. This allows a mobile station that received this signal pattern to locate itself by using the positional information about the base stations, sending timing (or information on phase shift from the reference time) of each...http://www.google.nl/patents/US20020004398?utm_source=gb-gplus-sharePatent US20020004398 - Method of providing location service using CDMA-based cellular phone system, a method of measuring location and location system
Publicatienummer US20020004398 A1
Aanvraagnummer US 09/781,187
Publicatiedatum 10 jan 2002
Prioriteitsdatum 10 juli 2000
Ook gepubliceerd als US7711376
Publicatienummer 09781187, 781187, US 2002/0004398 A1, US 2002/004398 A1, US 20020004398 A1, US 20020004398A1, US 2002004398 A1, US 2002004398A1, US-A1-20020004398, US-A1-2002004398, US2002/0004398A1, US2002/004398A1, US20020004398 A1, US20020004398A1, US2002004398 A1, US2002004398A1
Uitvinders Atsushi Ogino, Mikio Kuwahara, Tomoaki Ishifuji
Patentcitaties (23), Verwijzingen naar dit patent (50), Classificaties (9), Juridische gebeurtenissen (4)
US 20020004398 A1
At least three base stations transmit a specific signal pattern at given intervals. This allows a mobile station that received this signal pattern to locate itself by using the positional information about the base stations, sending timing (or information on phase shift from the reference time) of each signal pattern from the base stations, and signal pattern receiving time information. At least one of the above base stations changes the sending timing of the signal pattern. On this occasion, the mobile terminal or station is notified of the altered reference time offset (or information on phase shift from the reference time) of the sending timing or updated sending timing of the signal pattern.
transmitting a specific signal pattern at given intervals from at least three base stations, which allows a mobile terminal or station that received said signal pattern to locate itself by using positional information about said base stations, sending timing (or information on phase shift from the reference time) of each said signal pattern from said base stations, and signal pattern receiving time information;
making change to the sending timing of said signal pattern from at least one of said base stations; and
notifying said mobile terminal or station of the altered reference time offset (or information on phase shift from the reference time) of said sending timing or updated sending timing of said signal pattern on the occasion of said change.
2. The method of furnishing a location service according to claim 1, wherein in response to a request issued from said mobile terminal or station to at least one of said base stations, the notification of said altered reference time offset or updated sending timing of said signal pattern is sent to said mobile terminal or station.
3. The method of furnishing a location service according to claim 2, wherein after receiving information to identify said mobile terminal or station together with said request and verifying the identification of said mobile terminal or station, the notification of said altered reference time offset or updated sending timing of said signal pattern is sent to said mobile terminal or station.
4. The method of furnishing a location service according to claim 2, wherein charging data for said mobile terminal or station is updated in response to said request.
5. The method of furnishing a location service according to claim 1, wherein said mobile terminal or station is furnished with a decrypting key and said base stations which are at least three each encrypt said altered reference time offset or updated sending timing of each said signal pattern transmitted from them and broadcast such encrypted information over their broadcast channel or control channel.
6. The method of furnishing a location service according to claim 1, wherein the timing of sending said signal pattern from at least one of said base stations is changed regularly.
7. The method of furnishing a location service according to claim 1, wherein said base stations which are at least three each broadcast the positional information about their own and neighboring base stations over their broadcast channel or control channel or sends such information to said mobile terminal or station in response to said request therefrom.
8. The method of furnishing a location service according to claim 3, wherein said mobile terminal or station is notified of said altered reference time offset or updated sending timing of said signal pattern on one of different precision levels, according to the agreement that its owner concluded with the administrator of said base stations.
9. The method of furnishing a location service according to claim 2, wherein if said request is issued from said mobile terminal or station while the sending timing of said signal pattern is changed, a message that location is not possible is sent to said mobile terminal or station.
10. A method of furnishing a location service, comprising:
making change to the sending timing of a specific signal pattern of radio waves transmitted at given intervals from a base station regularly; and
notifying a specific mobile terminal or station of the altered reference time offset of said sending timing or updated sending timing of said signal pattern.
11. The method of furnishing a location service according to claim 10, wherein the identification of said mobile terminal or station is verified and said mobile terminal or station is notified of the altered reference time offset of said sending timing or updated sending timing of said signal pattern.
12. The method of furnishing a location service according to claim 11, wherein said mobile terminal or station is notified of said altered reference time offset or updated sending timing of said signal pattern on one of different precision levels, according to the agreement that its owner concluded with the administrator of at least three base stations including said base station.
13. The method of furnishing a location service according to claim 11, wherein the charging data for said mobile terminal or station is updated when the identification of said mobile terminal or station is verified.
14. The method of furnishing a location service according to claim 10, wherein said mobile terminal or station is furnished with a decrypting key and said base station encrypts said altered reference time offset or updated sending timing of said signal pattern transmitted from it and broadcasts such encrypted information over its broadcast channel or control channel.
15. A method of furnishing a location service comprising:
making change to the sending timing of a specific signal pattern of radio waves transmitted at given intervals from a base station regularly or at irregular intervals;
calculating the location of a mobile terminal or station, based on the data on receiving timing of said signal pattern at said mobile terminal or station; and
notifying said mobile terminal or station of the result of calculation.
16. The method of furnishing a location service according to claim 15, wherein the identification of said mobile terminal or station is verified and the location of said mobile terminal or station is calculated.
17. The method of furnishing a location service according to claim 16, wherein said mobile terminal or station is notified of the result of calculation of its location on one of different precision levels, according to the agreement that its owner concluded with the administrator of said base station.
18. The method of furnishing a location service according to claim 16, wherein the charging data for said mobile terminal or station is updated when the identification of said mobile terminal or station is verified.
19. A method of location whereby:
a mobile terminal or station to locate itself sends its ID and a request for the information on the sending timing of a specific signal pattern transmitted at given intervals from base stations in its vicinity to a base station in the zone where it stays; and
said mobile terminal or station locates itself by using the answer from said base station in the zone where it stays and the information on receiving timing of each said signal pattern from said base stations in its vicinity.
20. A method of location whereby:
a mobile terminal or station to locate itself is furnished with a decrypting key and decrypts the encrypted information on the sending timing of a specific signal pattern transmitted at given intervals from base stations in its vicinity, which is broadcasted from a base station in the zone where it stays; and
said mobile terminal or station locates itself by using the thus decrypted information and the information on receiving timing of each said signal pattern from said base stations in its vicinity.
21. The method of location according to claim 19, wherein said mobile terminal or station receives the positional information about the base stations in its vicinity over the broadcast channel or control channel from the base station in the zone where it stays.
22. A location system comprising at least three base stations and one mobile terminal or station, wherein:
at least one of said base stations changes the sending timing of said signal pattern; and
said mobile terminal or station locates itself by using the altered reference time offset or updated sending timing of said signal pattern, the positional information about said base stations, and the information on receiving timing of each said signal pattern from said base stations.
23. A location system comprising at least three base stations and one mobile terminal or station, wherein:
at least one of said base stations changes the sending timing of said signal pattern;
said base stations broadcast encrypted information on sending timing of each said signal pattern transmitted from their own and neighboring base stations over their broadcast channel or control channel; and
said mobile terminal or station decrypts the encrypted information on sending timing of each said signal pattern transmitted from base stations in its vicinity, broadcasted from a base station in the zone where it stays, by using a decrypting key, and locates itself by using the decrypted information, the positional information about said base stations, and the information on receiving timing of each said signal pattern from said base stations.
24. The location system according to claim 22 further comprising a server for storing the information on sending timing of each signal pattern transmitted from said base stations.
25. The location system according to claim 24, wherein said server instructs said base stations to change the sending timing of signal pattern.
26. A location system comprising at least three base stations and one mobile terminal or station, wherein:
said mobile terminal or station notifies a base station in the zone where it stays of the information on receiving timing of each said signal pattern transmitted from said base stations;
a base station in the zone where said mobile terminal or station stays or a server to which the base station connected calculates the location of said mobile terminal or station; and
the base station in the zone where said mobile terminal or station stays notifies said mobile terminal or station of the result of calculation.
27. The location system according to claim 26, wherein said server stores the information on sending timing of each said signal pattern transmitted from said base stations.
28. The location system according to claim 27, wherein said server instructs said base stations to change the sending timing of said signal pattern.
a specific signal generator that generates a specific signal pattern which is transmitted at given intervals from said base station;
a timing change unit that changes the sending timing of said signal pattern;
a generator of sending timing information that generates changed sending timing information; and
a transmitting unit that transmits said signal pattern and said sending timing information.
30. The base station according to claim 29, further comprising:
a receive unit that receives ID from a mobile terminal or station; and
a decision unit that judges whether said ID matches the registered one,
wherein said transmitting unit transmits said signal pattern, according to the judgment of said decision unit.
a sending timing information encryptor that encrypts changed sending timing information; and
a transmitting unit that transmits said signal pattern and the encrypted sending timing information.
a timing change unit that changes the sending timing of said signal pattern as instructed by a server;
a forwarding unit that forwards the information on a mobile terminal's or station's receiving timing of each signal pattern transmitted from at least three base stations to the server; and
a transmitting unit that transmits said signal pattern and delivers the result of calculating the location of said mobile terminal or station received from said server to said mobile terminal or station.
33. A server to which at least three base station connect including:
a storage means for storing the information on sending timing of a specific signal pattern transmitted at given intervals from said base stations.
34. The server according to claim 33, further including:
a generator of instruction to change sending time for controlling the sending timing of each signal pattern from the said base stations; and
a transmitting unit that transmits the instruction to change the sending timing to the above base stations.
35. The server according to claim 33, further including:
a calculating unit that calculates the location of said mobile terminal or station by using the information on the mobile terminal's or station's receiving timing of signal pattern, which the server received via one of the above base stations, sending timing of each signal pattern from the base stations, and the positional information about the base stations.
36. A mobile terminal or station to locate itself comprising:
a receive circuit that receives the information on sending timing of a specific signal pattern that at least three base stations are transmitting at given intervals from any one of said base stations;
a memory that retains the positional information about said base stations;
a circuit to measure receiving time that measures the receiving timing of each signal pattern transmitted from the above base stations; and
a calculate circuit that calculates the location of the mobile terminal or station by using the above information on sending timing, the positional information about the above base stations, and the information on timing of receiving each signal pattern from the above base stations.
37. A mobile terminal or station to locate itself comprising:
a receive circuit that receives the encrypted information on sending timing of a specific signal pattern that at least three base stations are transmitting at given intervals over the broadcast channel or control channel from any one of said base stations;
a decryptor that decrypts said encrypted information;
38. A method of supplying signal pattern sending timing information whereby:
a plurality of levels of location precision based on the information on sending timing of a specific signal pattern transmitted at given intervals from a base station are provided;
a level of location precision is predetermined by the agreement between the owner of a mobile terminal or station and the administrator of the base station and the mapping between this level and each mobile terminal or station is stored in a storage device; and
in response to the request from said mobile terminal or station, said mobile terminal or station is notified of said sending timing on a precision level predetermined by said agreement.
39. A method of supplying specific signal sending timing information whereby:
an decrypting key is installed into a mobile terminal or station;
the sending timing of a specific signal pattern periodically transmitted from a base station is changed regularly or at irregular intervals; and
the information on said sending timing is encrypted and broadcasted.
40. The method of supplying signal pattern sending timing information according to claim 39, wherein:
a plurality of levels of location precision based on the information on said sending timing are provided;
each level of said information is encrypted and broadcasted;
a decrypting key for decrypting such information on a precision level predetermined by the agreement between the owner of the mobile terminal or station and the administrator of the base station is installed into said mobile terminal or station.
41. A method of supplying signal pattern sending timing information whereby:
a plurality of levels of location precision based on the information on sending timing of a specific signal pattern periodically transmitted from a base station are provided;
a level of location precision is predetermined by the agreement between the owner of a mobile terminal or station and the administrator of the base station and the mapping between this level and each mobile terminal or station is stored in a storage device;
the location of said mobile terminal or station is calculated on the level of location precision predetermined by said agreement, based on the information on said mobile terminal's or station's receiving timing of said signal pattern;
said mobile terminal or station is notified of the result of calculation.
[0005]FIG. 25 shows a model of the above location system formed by three base stations located on a plane. An object 91 represents a mobile station and three base stations are labeled 921, 922, and 923, respectively. Coordinates (x, y) represent the position (coordinates) of the mobile station 91 and coordinates (x1, y1), (x2, y2), and (x3, y3) represent the positions (coordinates) of the base stations 921, 922, and 923, respectively. The base stations 921, 922, and 923 operate, based on common reference time T0. At the same time, the base stations 921, 922, and 923 have predetermined time offsets TO1, TO2, and TO3, respectively. The base stations 921, 922, and 923 repeats the transmission of same PN (pseudonoise) sequences at a same rate over their pilot channels. When the base stations 921, 922, and 923 transmit the PN sequences, the time at which the first pulse of the PN sequences is sent out (in other words, the time at which the transmission of the PN sequences starts) is delayed, according to the time offsets TO1, TO2, and TO3, respectively. Because the base stations also transmit their time offsets over their sync channels, respectively, the mobile station 91 can obtain the above time offsets TO1, TO2, and TO3. In addition, because the base stations transmit the time offsets of their neighboring base stations over their paging channels, the mobile station 91 can obtain the above time offsets TO1, TO2, and TO3. TP1, TP2, and TP3 respectively represent signal propagation time from the base stations 921, 922, and 923 to the mobile station. T1, T2, and T3 respectively represent the time when the first pulse of the PN sequences sent out from the base stations 921, 922, and 923 has arrived at the mobile station 91, measured at the mobile station 91
The position (coordinates) (x, y) of the mobile station 91 can be obtained by solving the following simultaneous equation where c is the velocity of light (x1, y1), (x2, Y2), and (x3, y3) are assumed to be known, but five values, x, y, TP1, TP2, and TP3 are unknown.
(x−x1)^ 2+(y−y1)^ 2=(c×TP1)^ 2
(x−x2)^ 2+(y−y2)^ 2=(c×TP2)^ 2
(x−x3)^ 2′+(y−y3)^ 2=(c×TP3)^ 2 (1)
T2−T1=(TO2+TP2)−(TO1+TP1)
T3−T1=(TO3+TP3)−(TO1+TP1)
If equation 1 is used, a mobile station operated by someone who is not a subscriber to a cellular phone system can locate itself.
[0016]FIG. 1 is a diagram schematizing an example of the location system using a CDMA-based cellular phone system, offered by the present invention;
[0017]FIG. 2 is a diagram showing an example of the configuration of a server in the location system offered by the present invention;
[0018]FIG. 3 is a diagram showing an example of the mobile station configured to embody the present invention;
[0019]FIG. 4 is a diagram schematizing an example of the means of giving a reference time offset by controlling the clock for transmission from a base station, which may be adopted to embody the location system offered by the present invention;
[0020]FIG. 5 is a diagram schematizing an example of the means of giving a reference time offset that varies over time by controlling the clock for transmission from a base station, which may be adopted to embody the location system offered by the present invention;
[0021]FIG. 6 is a timetable illustrating an example of reference time offset control schedule setting which may be adopted to embody the location system offered by the present invention;
[0022]FIG. 7 is a timetable illustrating another example of reference time offset control schedule setting which may be adopted to embody the location system offered by the present invention;
[0023]FIG. 8 is a diagram showing an example of the server configuration which may be adopted in the present invention;
[0024]FIG. 9 illustrates an example of the flow of location service that is implemented by the location system offered by the present invention;
[0025]FIG. 10 illustrates another example of the flow of location service that is implemented by the location system offered by the present invention;
[0026]FIG. 11 is a diagram schematizing a second preferred embodiment of the location system using a CDMA-based cellular phone system, offered by the present invention;
[0027]FIG. 12 is a diagram schematizing a third preferred embodiment of the location system using a CDMA-based cellular phone system, offered by the present invention;
[0028]FIG. 13 is a diagram showing an example of the server configured to work in the third embodiment of the invention;
[0029]FIG. 14 is a diagram showing another example of the server configured to work in the third embodiment of the invention;
[0030]FIG. 15 is a diagram showing an example of the base station configured to work in the third embodiment of the invention;
[0031]FIG. 16 illustrates an example of the flow of location service that is implemented by the third embodiment of the invention;
[0032]FIG. 17 is a diagram schematizing a fourth preferred embodiment of the location system using a CDMA-based cellular phone system, offered by the present invention;
[0033]FIG. 18 is a diagram schematizing a fifth preferred embodiment of the location system using a CDMA-based cellular phone system, offered by the present invention;
[0034]FIG. 19 is a diagram showing an example of the mobile station configured to work in the fifth embodiment of the invention;
[0035]FIG. 20 is a diagram shoring an example of the base station configured to work in the fifth embodiment of the invention;
[0036]FIG. 21 is a diagram shoring an example of the sever configured to work in the fifth embodiment of the invention;
[0037]FIG. 22 illustrates an example of the flow of location service that is implemented by the fifth embodiment of the invention;
[0038]FIG. 23 illustrates an example of the flow of location service that is implemented by a sixth preferred embodiment of the invention;
[0039]FIG. 24 is a diagram showing an example of the base station configured to work in the sixth embodiment of the invention; and
[0040]FIG. 25 is a diagram schematizing a conventional location system using a CDMA-based cellular phone system.
The outline of a location system using a CDMA-based cellular phone system, offered by the present invention, will now be described with reference to FIG. 1. In FIG. 1, a mobile station is labeled 1, base stations are labeled 21, 22, and 23, and a server is labeled 3.
(x−x3)^ 2+(y−y3)^ 2=(c×TP3)^ 2 (2)
T2−T1=(TO2+TP2+Td2)−(TO1+TP1+Td1)
T3−T1=(TO3+TP3+Td3)−(TO1+TP1+Td1)
With regard to embodying the invention as described above, when the server may notify the mobile station of the above reference time offsets that have been rounded off to the required level of location precision, according to the agreement of location service. In this case, on the server 3, after retrieving the reference time offsets of signal pattern transmission from the base stations from the table A 31, its control unit 31 rounds off the reference time offsets to the required level of location precision with error inclusion, based on the charging data contained in the table B 32. If, for example, location precision of 60 meters is required, the reference time offsets should be rounded off such that location can be calculated in steps of 0.2 μsec [=60 m÷(3×108 m/sec)]. In this way, charge setting is possible, according to the location precision level as required by the subscriber who contracted with the service provider for location service.
Using an example case where the location system offered by the present invention is applied to a cellular phone system compliant with TIA/EIA/IS-95, the permissible range within which the reference time offsets Td1, Td2, and Td3 of signal pattern transmission from the base stations may be varied will be described below. For cellular phone systems compliant with TIA/EOA/IS-95, transmission time delay of pilot channel PN sequences should desirably fall within the range of ±3 μsec of CDMA system time and must fall within the range of ±10 μsec of CDMA system time. Thus, the permissible range within which the reference time offsets Td1, Td2, and Td3 of signal pattern transmission from the base stations may be varied is set at ±10 μsec of CDMA system time. Because a distance estimation error of 300 m takes place per temporal error of 1 μsec, a maximum error of 3000 meters would take place when the mobile station location is calculated. Even if the permissible range within which the reference time offsets Td1, Td2, and Td3 of signal pattern transmission from the base stations may be varied is set at ±3 μsec of CDMA system time, a maximum of error of 900 meters would take place when the mobile station location is calculated. Unless the mobile station is notified of the reference time offsets of signal pattern transmission from the base stations, a reliable location result is difficult to obtain for the observer who expects location precision on the order of 10 meters. Even if the range within which the reference time offsets can be varied is set as described above without having a bad effect on the cellular phone system, the present invention can sufficiently prevent the infrastructure of the location system from being used unfairly.
How the above scheduler 2023 can set a reference time offset control schedule will be described below. A first method is such that the reference time offset is altered once a day for a few tens of seconds at midnight. An example of altering the reference time offset according to the first method is shown in FIG. 6. This timetable illustrates how the reference time offset under control is altered for a scheduled time on the assumption that the location system of the invention is applied to the cellular phone system compliant with TIA/EIA/IS-95. Alteration to the reference time offset is executed for a few tens of seconds from 2 a.m. at midnight. For example, on April 19, the reference time offset is set at +8/16 PN chips. On April 20, this reference time offset is altered to +2/16 PN chips which is in turn altered to −18/16 PN chips on April 21. The alteration rate of the reference time offset is assumed to be 1/16 PN chips per second. By thus altering the reference time offset under control once a day, it is more difficult to presume such alteration for a person who does not have the knowledge of reference time offset setting. Therefore, this method is useful for preventing the infrastructure of the location system from being used unfairly. If this first method is applied, the server is required to simply make connection to each base station once a day to update the contents of the table A 31. If the mobile station accesses the server while the reference time offset is being altered on the base station, the server may send the mobile station a reply message such as “Reference time offset alteration is now in process; Access again after a while.” The time schedule by which reference time offset alteration will occur may be preset for each base station so that the server can know when the reference time offset is altered on each base station. Alternatively, each base station may notify the server of the start of reference time offset alteration. Alternatively, each base station may notify the server of the end of reference time offset alteration and the altered reference time offset.
A second method in which the scheduler 2023 sets a reference time offset control schedule is such that the reference time offset is always altered to give a distance error of a few meters for several minutes. An example of altering the reference time offset according to the second method is shown in FIG. 7. This timetable illustrates how the reference time offset under control is altered over time on the assumption that the location system of the invention is applied to the cellular phone system compliant with TIA/EIA/IS-95. In this timetable, for example, the reference time offset alters from ±0 to +144/128 PN chips during 24 hours from 0:00 at the left end on the transverse axis to the first 0:00 toward the right. The alteration rate of the reference time offset is assumed to be 1/128 PN chips for ten minutes (this is converted into a distance error of 1.9 m). By thus altering the reference time offset to give a distance error of a few meters for several minutes, it is more difficult to presume such alteration for a person who does not have the knowledge of reference time offset setting. Therefore, this method is useful for preventing the infrastructure of the location system from being used unfairly. If the second method is applied, the server must make connection to each base station to update the contents of the table A 31 so frequently as every several seconds. As compared with the first method, however, the second method provides more moderate alteration of the reference time offset. Therefore, even if the sever notifies the mobile station of the reference time offset before update as the result of improper access timing of the mobile station, the second method is useful for reducing the error in locating the mobile station to about a few meters, shorter than in the corresponding case with the first method.
[0063]FIG. 9 illustrates an example of the flow of location service that is implemented by the location system embodied as described hereinbefore. First, the location service provider contracts the user of a mobile terminal (station) and issues the mobile station ID to the user. The server retains the information on sending timing of a specific signal pattern transmitted at given intervals from the base station. When the sending timing is changed on the base station, the base station notifies the server of the update information on the sending timing. The server updates the sending timing information retained there. When the user wants to know the location of the user's mobile terminal (station), the mobile terminal (station) sends a request for the signal pattern sending timing information with the above ID to the server. After verifying the ID, the server updates the charging data for the user and furnishes the user with the sending timing information on the location precision level predetermined by the agreement of the contract by delivering this information to the user's mobile terminal (station). The user's mobile terminal (station) measures the time at which it receives each signal pattern transmitted from the base stations and calculates its location by using the sending timing information obtained from the server.
[0064]FIG. 10 illustrates another example of the flow of location service that is implemented by the location system as described hereinbefore. First, the location service provider contracts the user of a mobile terminal (station) and issues the mobile station ID to the user. The server sends the base station the instruction to change the sending timing of a specific signal pattern transmitted at given intervals from the base station. On receiving this instruction from the server, the base station changes the sending timing of signal pattern as specified in the instruction. The server retains the information on the sending timing of signal pattern and updates this information as it specified in the above instruction. When the user wants to know the location of the user's mobile terminal (station), the mobile terminal (station) sends a request for the signal pattern sending timing information with the above ID to the server. After verifying the ID, the server updates the charging data for the user and furnishes the user with the sending timing information on the location precision level predetermined by the agreement of the contract by delivering this information to the user's mobile terminal (station). The user's mobile terminal (station) measures the time at which it receives each signal pattern transmitted from the base stations and calculates its location by using the sending timing information obtained from the server.
A second preferred embodiment of the present invention will be described below. Many base stations usually exist in a location system using a CDMA-based cellular phone system. Furthermore, each base station consists of one or a plurality of sectors, each of which transmits pilot channel PN sequences. Different time offsets are assigned to the pilot channel PN sequences transmitted from the sectors of one base station. When the location of a mobile station is determined, all reference time offsets of PN sequences transmitted from the sectors of the base stations in the system are not necessary. Once the mobile station has succeeded in measuring the time at which it received PN sequences from some sectors respectively, the reference time offsets of the PN sequences transmitted from these sectors are effective for locating the mobile station. In the second embodiment, the mobile terminal identifies the sectors it is receiving PN sequences transmitted from there and sends the server a request to deliver the reference time offsets of the PN sequences as well as the identifiers of these sectors. The server retains the reference time offsets of PN sequences transmitted from the sectors mapped to the IDs pre-assigned to these sectors. The mobile station can easily identify the sector that is transmitting the PN sequences it received and obtain the sector ID. For example, in a cellular phone system compliant with TIA/EOA/IS-95, the time offset (TOi) of PN sequences transmitted from a sector and the ID (BS_ID) of the base station including the sector are transmitted over a paging channel of the base station. Based on these two items of information, the mobile station can identify the sector and obtain its ID. With reference to FIG. 11, this second embodiment of the present invention will be explained below. For convenience of explanation, the ID (BS_ID) of a base station X is assumed to be X. If the time offset of PN sequences transmitted from a sector of the base station X is TOi, the sector will be referred to as “sector TOi of the base station X” for its identification. Each of base stations 21′, 22′, 23′, 24′, 25′, and 26′ is assumed to comprise three sectors. A mobile station 1′is assumed to have received pilot channel PN sequences transmitted from the sector TO1 of the base station 21′, sector TO2 of the base station 22′, and sector TO3 of the base station 23′. To determine its location, the mobile station 1 sends the server 3 its ID and the IDs for identifying the sectors that are transmitting the pilot channel PN sequences it received, for example, (21′, TO1), (22′, TO2), and (23′, TO3). After verifying the ID of the mobile station 1′, the server 3′ retrieves the reference time offsets of PN sequences transmitted from the sectors by request and notifies the mobile station 1′ of the reference time offsets associated with the sector IDs (21′, TO1, Td1), (22′, TO2, Td2), and (23′, TO3, Td3). The mobile station 1′ obtains these reference time offsets and calculates its location from them. In this way, the mobile terminal may identify sectors it is receiving PN sequences transmitted from there and request the server to deliver necessary reference time offsets.
[0068]FIG. 13 shows an example of the server configured to calculate the location of a mobile station. As shown, the server 3 d to which at least three base stations connect comprises: a table A 31 d for storing the information (for example, reference time offset, herein) on the sending timing of a specific signal pattern (for example, pilot channel PN sequences, herein) that the above base stations are transmitting at given intervals; a table B 32 d for storing the IDs of the subscribers under the contract with the location service provider and charging data thereof; a table C 33 d for storing the positional information (coordinates) about the above base stations; and a control unit 30 d. The control unit 30 d includes a calculating unit 303 d that calculates the location of the mobile station by using the information on signal pattern receiving time measured at the mobile station, which the server received via one of the above base stations, sending timing of each signal pattern from the base stations, and the positional information about the base stations.
[0069]FIG. 14 shows an example of the server configured to instruct each base station to change the signal pattern sending timing and calculate the location of a mobile station. As shown, the server 3 e to which at least three base stations connect comprises: a table A 31 e for storing the information (for example, reference time offset, herein) on the sending timing of a specific signal pattern (for example, pilot channel PN sequences, herein) that the above base stations are transmitting at given intervals; a table B 32 e for storing the IDs of the subscribers under the contract with the location service provider and charging data thereof; a table C 33 e for storing the positional information (coordinates) about the above base stations; and a control unit 30 e. The control unit 30 e includes: a generator of instruction to change sending time 301 e for controlling the sending timing of each signal pattern from the above base stations; a transmitting unit 302 e that transmits the instruction to change the sending timing to the above base stations; and a calculating unit 303 e that calculates the location of the mobile station by using the information on signal pattern receiving time measured at the mobile station, which the server received via one of the above base stations, sending timing of each signal pattern from the base stations, and the positional information about the base stations.
[0070]FIG. 15 shows an example of the base station configured to work in the location system wherein the server instructs each base station to change the signal pattern sending timing and calculates the location of a mobile station and the notification of the result of this calculation is sent to the mobile station via any base station. The base station 20 e comprises: a specific signal generator 201 e that generates a specific signal pattern (for example, pilot channel PN sequences) which is transmitted at given intervals from the base station; a timing change unit 202 e that changes the signal pattern sending timing as instructed by the server; a forwarding unit 205 e that forwards the information on a mobile station's receiving timing of each signal pattern transmitted from at least three base stations to the server; and a transmitting unit 204 e that transmits the signal pattern and also delivers the result of calculating the location of the mobile station received from the server to the mobile station.
[0071]FIG. 16 illustrates the flow of location service that is implemented by the location system wherein the server instructs each base station to change the signal pattern sending timing and calculates the location of a mobile station and the notification of the result of this calculation is sent to the mobile station via any base station. First, the location service provider contracts the user of a mobile terminal (station) and issues the mobile station ID to the user. The server sends the base station the instruction to change the sending timing of a specific signal pattern transmitted at given intervals from the base station. On receiving this instruction from the server, the base station changes the sending timing of signal pattern as specified in the instruction. The server retains the positional information (coordinates) about the base stations and the information on the sending timing of signal pattern and updates this timing information as it specified in the above instruction. When the user wants to know the location of the user's mobile terminal (station), the mobile terminal (station) measures time when it received each signal pattern transmitted from at least three base stations and sends the notification of this receiving timing information with the above ID to the server via one of the above base stations. After verifying the ID, the server updates the charging data for the user as required and calculates the location of the mobile terminal (station) by using the received information on signal pattern receiving time measured at the mobile terminal (station) and the information on sending timing of each signal pattern from the above base stations, and the positional information about the base stations. At this time, the server executes this calculation on the location precision level predetermined by the agreement of the contract. Then, the server notifies the mobile terminal (station) of the location of the mobile terminal (station).
With reference to FIGS. 18, 19, 20, and 21, a fifth preferred embodiment of the present invention will be explained below. FIG. 18 schematizes the location system configured, according to the fifth embodiment of the invention, which comprises base stations 21 f, 22 f, and 23 f, a mobile station 1 f, and a server 3 f.
A base station 20 f, which is representative of the base stations 21 f, 22 f, and 23 f, as is shown in FIG. 20, comprises: a specific signal generator 201 f that generates a specific signal pattern (for example, pilot channel PN sequences) which is transmitted at given intervals from the base station; a timing change unit 202 f that changes the signal pattern sending timing as instructed by the server; a sending timing information encryptor 206 f that encrypts the information on sending timing of each signal pattern from the base stations (for example, reference time offsets ({Td1, Td2, Td3}) delivered from the server 3 f and generates encrypted information E on signal pattern sending timing ({Td1, Td2, Td3}); and a transmitting unit 204 f that transmits pilot channel PN sequences, according to the above sending timing, and broadcasts the above encrypted information E on signal pattern sending timing ({Td1, Td2, Td3}).
The server 3 f, as is shown in FIG. 21, comprises: a generator 301 f of instruction to change sending timing that issues the instruction to alter each of the reference time offsets Td1, Td2, and Td3 of the signal pattern transmitted from each of the base stations 21 f, 22 f, and 23 f; a table A 31 f for storing the reference time offsets Td1, Td2, and Td3 which may be altered as described above; and a transmitting unit 302 f for delivering the instruction to alter each of the reference time offsets Td1, Td2, and Td3 to one of the base stations 21 f, 22 f, and 23 f.
The mobile station 1 f, as is shown in FIG. 19, comprises: a receive circuit 11 f for receiving paging channel signals on which the above encrypted information E on signal pattern sending timing ({Td1, Td2, Td3}) is superimposed; a circuit to measure receiving time 12 f for measuring receiving timing T1, T2, and T3 of pilot channel PN sequences from the base stations; a memory 13 f in which the positional information (coordinates) about the base stations {(x1, y1), (x2, Y2), (x3, Y3)} is stored; a decryptor 15 f that decrypts the encrypted information E on signal pattern sending timing ({Td1, Td2, Td3}) transmitted over the above paging channel to obtain the information on sending timing of each signal pattern from the base stations, for example, reference time offsets (Td1, Td2, Td3); and a calculate circuit 14 f that calculates the location of the mobile station, based on the measured receiving timing of pilot channel PN sequences from the base stations, the positional information (coordinates) about the base stations, and the reference time offsets of signal pattern transmission from the base stations obtained by the above decryption.
[0078]FIG. 22 illustrates the flow of location service that is implemented by the fifth embodiment of the invention. First, the location service provider contracts the user of a mobile terminal (station) and installs a decrypting key for the location precision level specified by the agreement of the contact into the mobile terminal (station). The server sends the base station the instruction to change the sending timing of a specific signal pattern transmitted at given intervals from the base station. The server retains the information on the sending timing of signal pattern and updates this information as it specified in the above instruction. On receiving this instruction from the server, the base station changes the sending timing of signal pattern as specified in the instruction. Moreover, the base station encrypts the information on the changed sending timing of signal pattern and periodically transmits the thus encrypted information over a broadcast channel. When the user wants to know the location of the user's mobile terminal (station), the mobile station decrypts the above encrypted information on the sending timing of signal pattern transmitted over the broadcast channel with the decrypting key installed in it. The precision of this sending timing information obtained by decryption may vary, according to the agreement of the contract. The user's mobile terminal (station) measures time when it received each signal pattern transmitted from at least three base stations and calculates its location, based on the above sending timing information obtained by decryption.
[0080]FIG. 24 shows an example of the base station configured to work in the sixth embodiment of the invention. As shown, the base station 20 g comprises: a specific signal generator 201 g that generates a specific signal pattern which is transmitted at given intervals from the base station; a timing change unit 202 g that changes the signal pattern sending timing; a generator of sending timing information 207 g that generates changed sending timing information; a receive unit 208 g that receives ID from the mobile station; a decision unit 209 g that judges whether the received ID matches the registered one; and a transmitting unit 204 g that transmits the above signal pattern and also delivers the above sending timing information to the mobile station, according to the judgment of the decision unit.
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Classificatie in de VS 455/456.5, 455/457
Internationale classificatie H04J13/00, G01S5/14, H04M3/42, H04W64/00, H04W4/02
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Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:OGINO, ATSUSHI;KUWAHARA, MIKIO;ISHIFUJI, TOMOAKI;SIGNINGDATES FROM 20001227 TO 20010104;REEL/FRAME:011572/0299
4 mei 2014 LAPS Lapse for failure to pay maintenance fees
24 juni 2014 FP Expired due to failure to pay maintenance fee