Method and system for avoiding location update by mobile terminals being in a train and corresponding location information providing system

Background of the Invention

Field of the Invention

The present invention relates to a method and a wireless communication system for managing information on locations of mobile stations and a location information providing system.

Description of the Related Art

In the conventional mobile communication system, a device for managing location of a plurality of mobile stations is provided, to store information about which area (called "location area') each of mobile stations is located. When an incoming call directed to a mobile station occurs, the device identifies the location area. Next, the device generates paging signal to transmit to the mobile station via a switch covering the location area and one of the base stations belonging to the switch.

In the registration of a location area, firstly a mobile station receives information on location area. Secondly, the mobile station transmits a number to identify the mobile station and the location area information, via the base station and the switch. Especially, there is a location management system of a mobile station in a train. In such a system, a communication device is provided in a train, to collectively manage location registration of all mobile stations in the train (reference will be made to Japanese Patent Publication H11-355835A).

However, it is cumbersome and costs a lot to provide such device in a train capable of processing requests of location registration from many mobile stations. Even if such devices are introduced, base stations and switches still must process large amounts of request especially in an urban city where many trains run. Specifically, radio channels have to be allocated to exchange signals for location registration between a location registration server and mobile stations. Therefore, radio frequency bandwidth available for voice and data communication is restricted thereby communication traffic volume increases. It is often the case that a moving object such as a train or a bus moves to a place such as a tunnel into which a radio wave transmitted from a base station does not propagate. In this case the base station does not receive any signals either from the object and a mobile station in the object, so that the location server cannot recognize a location of the mobile station.

There is a system for providing location information stored in the location server to an external terminal. In such a system, a location of a mobile station can be tracked in real-time. In principle, it is possible to know a future location of a mobile station as long as a user of the mobile station gets off a train. However, in the conventional system such information on future location cannot be provided.

Further, in US 6,272,344 B1, there is described a position registration method for a mobile communications system which can achieve reduction of the number of times of position registration of a mobile station without any restriction when the mobile station is present in a mobile space, e.g., an electric train or a bus, and the mobile station moves together with the mobile space. Heretofore, an existing position of a mobile space such as an electric train or a bus in a real space is position registered into a switching control station through a base station using a control channel similarly to mobile stations.

Further, in Maass H.: 'Open mobility management platform with directory-based architecture and signalling protocols', OPEN ARCHITECTURES AND NETWORK PROGRAMMING, 1998 IEEE San Francisco, CA, USA, 3-4 April 1998, New York, NY, USA, IEEE, 3 April 1998, pages 72-87, there is described an open mobility platform with directory-based architecture and signalling protocols. In particular, the document aims at provision of mobility management services as basis for introduction of user and terminal mobility into private communication networks.

Still further, in WO96/13951 A, there is described a method and apparatus for detecting and predicting motion of mobile terminals based on previously stored locations of mobile terminals and a prediction of the next location of the mobile terminal based on a selection of stored location sequences in relation to the mobile station.

The present invention, as its object, provides a wireless communication system at a low cost, in which locations of mobile stations moving together with an object such as trains and buses are tracked accurately and efficiently. In addition, the present invention provides a communication system for providing a future location of a mobile station to a third party.

To attain the above object, a method of the present invention for managing location information on a mobile station in an object by a server on a mobile network comprises the steps of independent claim 1.

Further, the object outlined above is achieved with a communication system having the features of independent claim 8.

Brief Description of the Drawings

<ul id="ul0001" list-style="none" compact="compact"><li>Fig. 1 shows a communication system based on the first embodiment.</li><li>Fig. 2 is a schematic diagram of a location server in the system.</li><li>Fig. 3 shows a detail of a location table in the system.</li><li>Fig. 4 is a schematic diagram of an object information server in the system.</li><li>Fig. 5 is a sequence diagram of the system.</li><li>Fig. 6 is a schematic diagram of an object information server used for a communication system based on the second embodiment.</li><li>Fig.7 shows details of a first and a second location table of the location server.</li><li>Fig. 8 is a sequence diagram of the system based on the second embodiment.</li><li>Fig. 9 is an information providing system based on the third embodiment.</li><li>Fig. 10 is a schematic diagram of an information server in the system.</li><li>Fig. 11 is a schematic diagram of a mobile station.</li><li>Fig.12 is a sequence diagram of the system.</li><li>Fig. 13 is a schematic diagram of an object management device in an information providing system based on the fourth embodiment.</li><li>. Fig.14 shows a detail of a management table of the object information server.</li><li>Fig.15 is a sequence diagram of the information providing system based on the fourth embodiment.</li></ul>

Detailed Description

Reference will now be made in detail to the preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings.

1. First embodiment

1-1. Configuration of a communication system of first embodiment

Fig.1 illustrates a wireless communication system based on the first embodiment of the invention. As shown in Fig.1, the system comprises a mobile network NET, a moving object 2, and a traffic control device 30. Object 2 is, for example, a train, a bus, and other means of transportation. It will now be described assuming that Moving object is a train. In the figure only a moving object 2 is illustrated but in actuality, many trains 2 exist in the system. Traffic control device 30 manages movements of the trains. Traffic controls device 30 keeps track of each train, specifically, has present location, train schedule, and other information related to the train such as delay. Also, Traffic control device 30 generates movement information INFx, which is the latest information on a movement of an object, to transmit to other devices.

Movement information INFx includes object location information INF1 on a location of Object 2 and related information INF2 for the movement. Specifically, a form of location information INF 1 takes a form of "Longitude, Latitude" or "Name of line, Distance from neighboring station, Direction" . For example, the detail of Location information INF1 is "Long. 136° 15' E., 35° 45' N.", or " Tokaido line, 2km from Shinagawa, to Yokohama" . Related information INF2 includes a name of a train such as "Hikari No. 10" and a delay or suspension.

Mobile communication network NET has a plurality of base stations 3-1, 3-2, ...; a plurality of switches 4-1,4-2, ...; object information server 40A; and location server 50A. Location server 50A manages location area information of all mobile stations it covers.

Each of base stations 3-1, 3-2, ... is provided at a certain distance from neighboring one and covers a base station areas 4s each lettered " 4a" through " 4f" as shown in Fig.1. In other words, each of base stations can carry out radio communication with mobile stations within one of base station areas 4 it covers. As shown, each of base stations 3-1 through 3-6 covers each of Base station areas 4a through 4f. Each Location area 5 lettered 5A and 5B is a compilation of base station areas 4s. Each of Switches 4-1,4-2,...covers one of Location areas 4.

Object 2 has a transmitting device TD and moves on a railroad L. Railroad L extends across boundaries of Location areas 5. Transmitting device transmits an object ID number IDt by radio. Each of Objects 2 has a unique object ID number IDt. Each of Mobile stations 1 stores a unique mobile ID number IDm to identify a mobile station uniquely. Mobile ID number is, for example, a phone number.

When a user of Mobile station 1 is not in a train, Mobile station 1 receives and stores Location area information INF from Base station 3. When Mobile station 1 moves into another Location area 1, Mobile station 1 notifies Location information INF and Mobile ID number IDm to mobile communication network NET via Base station 3. When a user of Mobile station 1 gets aboard Object 2, Mobile station 1 receives Mobile ID number IDm from Transmitting device TD and notifies Mobile ID number IDm and received Object ID number IDt to mobile communication network NET via Base station 3.

Specifically, Mobile station 1 keeps watching on reception of Object ID number IDt. Only when Mobile station receives Object ID number IDt, Mobile ID number IDm and Object ID number IDt are transmitted to Mobile communication network NET. In other words, Location area information INF is not transmitted during the ride. This results in a reduction of frequency of transmission of information on location about a mobile station that is necessary for a registration.

1-2. Configuration of Location server 50A

As shown in Fig.2, Location server 50A has a control unit 51 and a location table TBL. Control unit 51 reads from or writes to Location table TBL data. In addition, Control unit 51 carries out communication with Object information server 40A and Switch 4, to manage locations of all Mobile stations 1 in Mobile communication network NET. In addition, Location server 50A generates paging signal when an incoming call for Mobile station 1 is issued. Fig.3 shows information stored in Location table TBL. Location table TBL has a plurality of records Rb1, Rb2, ..., in each of which a Mobile ID number IDm and location information of a mobile station are stored. The location information is either Location information INF or an Object ID number. Specifically, when a Mobile station 1 is in a train Object ID number IDt is stored, while when not in a train Location area information INF is stored.

For example, if a mobile station whose Mobile ID number IDm is "X0001", is in Object 2 whose Object ID number is "A01234", "X00001" and "A01234" are stored in Rb1 of Location table TBL correspondingly as shown in Fig.3. If a mobile station whose Mobile ID number is "X00003" is not in Object 2, Mobile ID number "X00003" and Location area information INF "5B" are stored correspondingly in a record Rb3.

1-3. Configuration of Object information server 40A

Fig.4 is a schematic diagram of Object information server 40A. As shown, Location information server has a control unit 41 and a convert unit 42. Control unit 41 carries out communication with Traffic control device 30 and Location server 50A as well serves as nerve center of Object information server 40A. Convert unit 42 converts Object location information INF1 included in Movement information INFx sent from Traffic control device 30 into Location area information INF. In one example, Convert unit 42 has a first table for storing Location area information INF and locations represented by latitude and longitude correspondingly; and a second table for information on routes of trains and Location area information INF. Upon obtaining Movement information INF1 in a "Latitude, Longitude" form, Convert unit 42 retrieves from the first table Location area and outputs to Control unit 41 information corresponding to object location information INF. In case of reception of Movement information INF1 in a "Line name, Distance from neighboring station, Direction" form, Convert unit 42 retrieves from the second table and outputs to Control unit 41 a present location of Object 2 corresponding to the Object location information INF1.

It is noted that although Object location information INF1 could take various forms, conversion of any types of Location area information INF1 can be effected by Convert unit 42.

1-4. Operation of the system

One example of operations of a wireless communication system of the invention will now be described referring to the drawings. Fig.5 is a sequence diagram of the communication system. When Mobile station 1 comes into Object 2, the Mobile station 1 receives an Object ID number IDt sent from Transmitting device TD (step S1) and transmits to Location server 50A registration request including the Object ID number IDt and a Mobile ID number IDm via Base station 3 and Switch 4 (not shown) (step S2). When Location server 50A receives the registration request, the Object ID number IDt and the Mobile ID number IDm are extracted from the request and stored in Location table TBL (step S3).

For example, if the Mobile ID number IDm is "X0002" and the Object ID number is "A01234", "X0002" and "A01234" are stored correspondingly in Rb2 of Location table TBL as shown in Fig.3.

It is noted that even when a Mobile station 1 comes across a border between location areas, the Mobile station 1 does not transmit Location area information as long as the Mobile station 1 is in an object thereby keeps receiving Object ID number IDt.

When one of Switches 4 receives a call for Mobile station 1, the Switch 4 issues a location request REQ1 to Location server 50A (step S4). REQ1 includes Mobile ID number IDm of the Mobile station 1. When Location server receives Location request REQ1, Control unit 51 retrieves from Location table location information corresponding to the Mobile ID number (step S5). Control unit 51 judges whether received location information is Location area information INF or Object ID number IDt.

If Control unit 51 retrieves Location information INF, Control unit 51 transmits retrieved Location information INF to the Switch 4. In this case, Location server 50A generates and transmits to Object information server 40A location request REQ2 (step 6).

Object information server 40A generates and transmits to Traffic control device 30 a movement request REQ3 including the Object ID number IDt (step S7). Traffic control device 30 firstly converts received Object ID number IDt into a certain number available for Traffic device 30 and secondly generates Movement information INFx. Next, Traffic control device 30 transmits Movement response RES3 including the Object ID number IDt and the Movement information INFx to Object information server 40A (step S8).

Object information server firstly 40A converts Object location information INF1 included in received Movement information INFx into Location area information INF (step S9) and next transmits a location area response RES2 including the location area information INF and the Object ID number IDt to Location server 50A (step S10).

After the reception of Location area response RES2, Location server 50A transmits to Switch 4 a location area response RES1 including the location area information INF and the Object ID number IDt (step S11). Switch 4 issues a paging request including the Mobile ID number to Base stations 3 within a location area designated by the Location area information INF. When the Mobile station answers, the connection is established.

In this system a mobile station does not notify location area information to any nodes in a mobile network during the ride. Therefore, the load on the network is reduced thereby improves system performance. In addition, a communication device capable of registering many mobile stations in a train at one time is not necessarily introduced. The only device provided in a train is one for transmitting an ID number by radio. Therefore, this system can be established at a low cost In addition, since Convert unit is introduced to convert Movement information INFx into Location area information INF, information on location of a train can be managed regardless of data format of object location information which a traffic control device has.

2. Second embodiment

2-1. Configuration of a communication system

A wireless communication system based on the second embodiment is similar to that of the first embodiment, except that a location server 50B is introduced instead of Location server 50A. Fig.6 is a schematic block diagram of Location server 50B. As shown, Location server 50B has a control unit 51, first location table TBL1, and second location table TBL2. Second location table TBL2 is the same as Location table of the first embodiment Fig.7 shows details of the First location table and Second location table. First location table TBL1 has a plurality of records Ra1, Ra2,..., each storing Object ID number IDt and location area information INF correspondingly. It is noted that the records and Objects 2 are same in number. For example, if Object 2 is located within a location area 5A and Object ID number IDt is "A01234" , "A01234" and "5A" are stored in a record Ra1 of First location table TBL1 as shown in Fig.7.

In this system upon updating movement information INFx on an Object 2, Traffic control device 30 transmits the updated information to Object information server 40A. Object information server 40A firstly converts received information INFx into Location area information INF and secondly transmits the converted information INF to Location server 50B. Location server 50B receives and stores to First location table TBL1 the Movement information INFx. In this way information stored in First location table TBL1 is updated. Information stored in Second location table TBL2 is updated by notification from Mobile station 1, as described in the first embodiment.

2-2. Operation of the system

Operations of the wireless communication system based on the second embodiment will now be described referring to Fig.8. As shown, steps S1 through S3 are the same as those of first embodiment.

When Traffic control device 30 updates Movement information INFx, Traffic control device 30 transmits a movement notice N1 including a Mobile ID number and updated information INFx to Object information server 40A (step S21). When receiving Movement notice N1, Object information server 40A converts Object location information INF1 included in the Movement information INFx into Location area information INF (step S22). Next, Object information server 40A generates and transmits to Location server 50B an Area notice N2 (step S23).

Suppose here that Object 2 is "Tokaido Line" moving from Shinagawa station to Yokohama station and Shinagawa and Yokohama station are located within "5A" and "5B", respectively. When the train arrives at Yokohama station, Traffic control device 30 generates Object location information INF1 indicating a stop of the train at Yokohama station. Next, Traffic control device 30 transmits Movement notice N1 including the information INF1. Object information server 40A receives Movement notice N1. Convert unit 42 converts INF1 into Location area information INF. Control unit 41 generates and transmits to Location server 50B Area notice N2 including an Object ID number IDt and the location area information INF.

Location server 50B receives the Area notice N2 and updates location area information INF corresponding to the Object ID number IDt stored in First location table TBL1 (step S24). Specifically, if Object ID number IDt is "A01234", Location area information INF in record Ra1 is updated from "5A" to "5B" shown in Fig.7. In this way First table TBL1 has the latest information on movement.

In other words, Object information server 40A does not ask Traffic control device for movement information when a call for Mobile station 1 in Object 2 is issued. Therefore, Location server 50B is able to obtain location area information on the mobile station quickly, thereby Switch 4 is able to route incoming calls effectively.

3.Third embodiment

An information providing system based on the third embodiment is an application of the system based on the second embodiment.

3-1. Configuration of the system

Fig.9 is a schematic diagram of the system of this embodiment This system differs from that of the second embodiment only in having a Location information server 60, Client terminal 70, and Mobile station 1A instead of Mobile station 1. Client terminal 70 is, for example, a Personal Computer (PC), Personal Digital Assistants (PDA), mobile phone, and other communication devices, which carry out communication with Location information server 60.

Fig.10 is a schematic block diagram of Location information server 60. As shown, Location server has a Central Processing Unit (CPU) 61, Read Only Memory (ROM) 62, Random Access Memory (ROM) 63, Interface 64, and Hard disk 65. Location information server 60 provides location information of Mobile station 1A responsive to a request from Client terminal 70.

Specifically, CPU61 controls all the functions of all devices in Location information server 60 and executes applications. ROM62 stores, for example, a boot program. RAM 63 temporarily stores data or application programs for CPU61. Hard disk 65 stores application programs, which are a communication program for the communication with Client terminal 70 and Location server 50B, an estimation program for the estimation of a future location of Object 2, and a call program for calling Mobile station 1 on the basis of Location area information INF. Bus 150 links all devices.

Mobile station 1A differs form Mobile station 1 in having functions of generation and transmittance of location information. Fig.11 is a schematic diagram of Mobile station 1A. As shown, Mobile station 1A has a control unit 100, Global Positioning Systems (GPS) receiver 110, radio device 120, input device 130, Liquid Crystal Display (LCD) 140, and Bus 150. GPS receiver 110 receives radio wave sent by a satellite and generates information on the present location of Mobile station 1A including the longitude and latitude. Radio device 120 carries out radio communication with Base station 3 under control of CPU61. Input device 130 has buttons including Push Button (PB) and cursor keys and sends information on a user' s direction into Control unit 100. LCD 140 displays information. Control unit 100 has a CPU 111, ROM 112, RAM 113, and EEPROM 114; and controls all the functions of all devices in Mobile station 1A. ROM 112 has application programs for the control of devices, communication with Location information server 60, and generation of related information.

The related information includes, for example, a direction and velocity of Object 2. RAM 113 temporarily stores data and application programs for CPU 111. EEPROM 114 nonvolatile memory and stores updated application programs. Bus 150 electrically connects all devices.

3-2. Operation of the system

Fig.12 is a sequence diagram of the information providing system. It is noted that this system carries out procedures for updating location area information INF, which is the same as that in the second embodiment.

A user operates Client terminal 70 with Input device 130 to access Location information server 60. Client terminal 70 displays in LCD 140 direction for input of Mobile ID number. When the user input a Mobile ID number IDm (phone umber, for example), Client terminal 70 transmits to Location information server 60 location request REQ 4 including the Mobile ID number IDm (step S31).

Upon receiving location request REQ 4, Location information server 60 transmits location request REQ 5 including the Mobile ID number to Location server 50B (step S32). Location server 50B receives location request REQ5 and retrieves location area information INF corresponding to the Mobile ID number IDm from First location table TBL1 and Second location table TBL2 (step S33). Furthermore, if Object ID number IDt is stored in Second Location table TBL2, Location server set a flag FLG to "1". If Object ID number IDt is not stored, the flag FLG is set to "0" (step S33).

Next, Location server 50 transmits to Location information server 60 a location request RES 5 including the Location area information INF and Flag FLG (step S34). Location information server 60 receives Location request RES 5 and executes the estimation program, to page Mobile station 1A (step S35). Specifically, Location information server pages, via a Switch, Base stations 3 located within an area identified by the Location area information INF, by sending a paging signal including Mobile ID number, In addition, if Flag FLG is set to "1" , Location information server 60 generates boarding information indicating whether a user of Mobile station 1A takes on a train. If Flag FLG is set to "0", the boarding information is not generated.

Upon receiving the paging signal, Mobile station 1A generates and transmits to Location information server 60 location information on the present location and related information including a direction and velocity (step S36).

Location information server 60 receives the location information and the related information from Mobile station 1A and transmits the location information, related information, and the boarding information to Client terminal 70 (step 37). For example, a user of a mobile station 1A aboard a train which is located at Long.136° 15' E., 35° 45' N. and heading toward South at a velocity of 46 Kilometers/hour. In this case, Location information "Long. 136° 15' E., 35° 45' N." , related information "46Km/h, South" , and boarding information "Now boarding" are transmitted to Client terminal 70.

In case a user is not aboard, Location information server 60 does not transmit the boarding information since Flag FLG in location request RES 5 is set to "0". As described above, people are able to obtain boarding information as well as location information of Mobile station 1A by operating Client terminal 70 in this system.

3-3. Modification of the third embodiment

As described above, the system of the third embodiment is comprised by adding the system of the second embodiment to Location server 60 and Client terminal 70. However, it is possible to introduce a system in which Location server and Client terminal 70 are added to the system of the first embodiment.

In this system, when Location server 50A receives Location request REQ 5 from Location information server 60, steps S5 through S10 shown in Fig.5 are carried out In this way Location server 50A obtains and transmits to Location information server 60 Location area information INF. Next, Location information server 60 pages Mobile station 1A, on the basis of the Location area information INF, similarly to the third embodiment.

4. Fourth Embodiment

4-1. Configuration of a system

An information providing system based on the fourth embodiment is the same as that of the third embodiment except for detailed function of Traffic control device 30 and use of an object information server 40B instead of 40A and Mobile station 1 instead of 1A. Specifically, Traffic control device 30 transmits Movement information INFx only when receiving a request from Object information server 40B, similarly to the first embodiment. Object information server 40B has a management table TBLk as shown in Fig.13, differing from Object information server 40A.

Fig.14 shows an example of information stored in Management table TBLk. Management table TBLk has a plurality of records Rc1, Rc2,..., each storing an Object ID number IDt, Movement information INFx, and timestamp T. Timestamp T represents the time when Movement information INFx is stored. Specifically, upon storing Movement information INFx, Control unit 51 obtains time from a timer not shown in the figure and writes the time to Management table TBLk. For one example, Record Rc1 indicates that Object location information INF1 "Long. 136° 15' E., 35° 45' N." is stored corresponding to Object ID number "A01234" at 13:00.

4-2. Operations of the system

Operations of the system will now be described referring to Fig.15. Fig.15 is a sequence diagram of the system. Steps S41 and S42 is the same as steps S31 and S32 as described above, respectively. Next, Location server 50B accesses Second location table TBL2. If Object ID number IDt is stored corresponding to a Mobile ID number, Location sever 50B sets the flag FLG to "1". If the Object ID number is not stored, FLG is set to "0" (step S43). If Object ID number IDt is stored, Location server 50B transmits movement request REQ 8 including the Object ID number IDt to Object information server 40B (step S44).

Object information server 40B receives the Movement request REQ 8 and retrieves from Management table TBLk Movement information INFx and Timestamp T, each corresponding to the Object ID number IDt. If Movement information INFx is not stored in Management table TBLk or a predetermined time has elapsed since the time represented by Timestamp T, Object information server 40B transmits a movement request REQ 9 to Traffic control device 30 (step S45).

Traffic control device 30 generates Movement information INFx about an Object 2 identified by the received Object ID number IDt and transmits to Object information server 40B a movement response RES 9 including the INFx (step S47). Object information server 40B transmits to Location server 50B a movement response RES 8 including the Movement information INFx (step S48).

If Movement information INFx is stored in Management table TBLk and a predetermined time has not elapsed since time T, Object information server 40B skips steps S45 through S47 and transmits a movement response RES 8 to Location server 50B (step S48).

Location server 50B transmits a movement response RES 7 including the Movement information INFx to Location information server 60 (step S49). Location information server 60 receives Movement response RES7 and extracts INF2 from the Movement information INFx included in Movement response RES 7 to estimate a future location of Object 2. A specific way of estimation is as follows:

Suppose that a user of a mobile station 1 is in a train whose Object ID number is "A01234" and Management table TBLk stores detailed information shown in Fig.14. When Location information server 60 receives a location request REQ6 from Client terminal 70, steps S42 through S49 are carried out as described above. As a result, Location information server 60 obtains Related information INF2 "Azusa No.2" . Next, Location information server 60 estimates a future location of the train referring to timetable data stored in Hard disk 65. The estimated location information generated by Location information server 60 includes, for example, " arrive at Kofu in 18 minutes" .

Next, Location information server 60 transmits to Client terminal 70 a location response RES6 including Object location information INF1, Related information INF2, and Boarding information (step S50). Specifically, INF1 "Long. 136° 15' E., 35° 45' N." , INF2 "Azusa No.2" , and Estimated location information " This train will arrive at Kofu in 18 minutes" , and Boarding information "Now boarding " is transmitted to Client terminal 70.

As described in this embodiment, a person is able to obtain the present and future location of a mobile station by inputting a Mobile ID number to Client terminal 70. In this system, location information of a Mobile station can be obtained, even if the mobile station in Object 2 cannot cany out radio communication with Base stations because Object 2 is moving through a tunnel, for example.

In addition, the number of inquires to Traffic control device 30 for getting the latest information on an object can be minimized. Since Object information sever 40B checks Timestamp T, to judge whether to obtain the information from Traffic control device 30. In other words, the information is obtained efficiently and precisely.

4-3. Modification of the fourth embodiment

It is possible that Traffic control device 30 transmits the latest Movement information INFx to Movement information server 40B every time the information INFx is updated. In this case, Location server is able to obtain the latest information on Object 2 and needs not to refer to Timestamp T.

It is also possible that a person uses Client terminal 70, to designate the detailed future location of a Mobile station. For example, a user inputs the desired time (an hour later, for example) in addition to Mobile ID number. After reception of Object location information INF1, Related information INF2, and Estimated location information, the Location information server 60 retrieves the estimated location of "Azusa No.2" (near Matsumoto station, for example) referring to the schedule stored Hard disk 65. Retrieved information is transmitted to Client terminal 70.

5. Supplement

As described in the above embodiments, when a user of Mobile station 1 gets aboard a train, Mobile station 1 receives Mobile ID number IDm from Transmitting device TD and notifies Mobile ID number IDm and received Object ID number IDt to Mobile communication network NET via Base station 3. However, it is possible that a device provided in Object 2 transmits Mobile ID numbers IDms each of which is sent from Mobile station 1 and Object ID number IDt, to mobile communication network NET. In this case, the device has the function of receiving Object ID number IDt and Mobile ID number IDm. As an example, Transmitting device TD may have the function. The point is that Object ID number IDt and Mobile ID number IDm are transmitted together to Mobile communication network NET, when a user gets aboard.

Although the foregoing description provides many variations for use of the present invention, these enabling details should not be construed as limiting in any way the scope of the invention, and it will be readily understood that the present invention is susceptible to many modifications, and equivalent implementations without departing from this scope and without diminishing its attendant advantages. It is therefore intended that the present invention is not limited to the disclosed embodiments but should be defined in accordance with claims which follow.