WO2001020944A1

WO2001020944A1 - Mobile station positioning system and method

Info

Publication number: WO2001020944A1
Application number: PCT/US2000/021690
Authority: WO
Inventors: Jerry Woo-Sam; Allen Lee
Original assignee: Ericsson Inc.
Priority date: 1999-09-14
Filing date: 2000-08-09
Publication date: 2001-03-22
Also published as: AU6626200A

Abstract

A system and method is disclosed for determining the location of a mobile telephone within a building or other predefined area. The predefined area is partitioned into a number of cell areas. The system includes at least one mobile telephone which periodically transmits a unique identification signal, a switching device and a plurality of base stations, each of which is associated with at least one distinct cell area such that a base station provides communication between the mobile telephone and the switching device when the mobile telephone is within the cell area associated with the base station. When the identification information transmitted by the mobile telephone is received by the switching device, the switching device determines the current cell area from which the mobile telephone most recently transmitted the identification information, generates temporal information pertaining to the most recent transmission of the identification information, and selectively stores current cell area information and the temporal information in memory. The stored current cell area information and temporal information are accessible by a computing device for reporting the positioning of the mobile telephone or monitoring the position thereof within the predefined area in substantially real time.

Description

MOBILE STATION POSITIONING SYSTEM AND METHOD

BACKGROUND OF THE INVENTION

Technical Field of the Invention

The present invention relates to a system and method for determining the location of a mobile telecommunications terminal, and particularly to a system and method for locating a mobile telephone within a building or compound.

Background and Objects of the Invention In an effort to facilitate communication, a number of companies typically have encouraged its employees to utilize mobile telephones during times when an employee is not in his office. In some instances, companies even provide mobile telephones to its employees in order to ensure that the provided employee may be easily contacted. With the proliferation of mobile telephone usage, the occurrences of lost or misplaced mobile telephones have understandably increased. Consequently, companies have a greater need today to locate lost or misplaced mobile telephones operated by its employees in order to ensure that its employees remain capable of communicating with the employer's clients or with each other.

Telephone call distribution systems are presently used by companies for receiving incoming telephone calls and forwarding the telephone calls to the appropriate individual, such as to an individual's mobile telephone. Communications systems even exist in which incoming calls to an employee's wireline desk telephone are automatically forwarded to the employee's mobile telephone in the event the wireline desk telephone is unanswered. There are circumstances, however, in which an employee's mobile telephone should not receive an incoming call. For instance, if an individual is in an important meeting or if a medical provider is in surgery, it may not be best to forward a telephone call thereto. In such circumstances, the location of an individual is best known before a telephone call is forwarded thereto. Companies thus have an interest in determining the location of an individual, such as an employee, before forwarding a telephone call to a mobile telephone used thereby.

Based upon the foregoing, there exists a need to better track the positioning of mobile telephones and thus their users within a building, compound or other predefined area. It is an object of the invention to provide a system and method for locating the position of mobile telephones in a building or other area.

It is another object of the present invention to provide a system and method for monitoring the positioning of users of mobile telephones in substantially real time.

Still another object of the present invention is to provide a mobile telephone positioning system and method which is capable of generating reports pertaining to the movement of mobile telephones within a building or other area.

SUMMARY OF THE INVENTION

The present invention overcomes shortcomings in existing positioning systems and satisfies a significant need for a system and method for determining a position of an active mobile telephone within a predefined area, such as a building or compound. The present invention is adapted for use by companies as part of or in conjunction with conventional communications systems maintained thereby. According to the present invention, the building or other predefined area is partitioned into a plurality of zones, with each zone including one or more cells defined therein. Each cell is associated with a base station such that a mobile telephone located within the cell communicates with the corresponding base station over the air interface. Each base station communicates with a telecommunications switch via a radio exchange. In this way, a mobile telephone located within any one of the cells is capable of participating in a speech communication.

According to the preferred embodiment of the present invention, each active mobile telephone which is not engaged in a speech communication periodically transmits a distinct identification signal. T h e identification signal is received by the base station corresponding to the cell in which the transmitting mobile telephone is located. The identification signal received by the base station is forwarded to the switch, whereupon the identification information is compared with a list of identification data to determine the owner of the mobile telephone. In addition, the switch is capable of determining the particular zone or cell from which the mobile telephone transmitted the identification signal as well as the time spent therein.

Specifically, each time the switch determines that a mobile telephone has entered a cell, the entered cell is logged in a database together with date and time information relating to the cell entry. In addition, a timer is activated and begins counting. When the switch then determines, based upon subsequent transmissions of the identification signal by the mobile telephone, that the mobile telephone has exited the cell and has entered a new cell, the timer is stopped and date/time information is stored into the database to document the entry into the new cell and exit from the present cell . In the event a mobile telephone no longer periodically transmits its identification signal, the timer is stopped and the value thereof is logged in the database to document the mobile telephone ceasing transmission in the cell. In this way, data is stored in the database for sufficiently documenting the position of the active mobile telephone within the building or other predefined area. The present invention further includes an interface for accessing the database via a terminal or computer, and software for compiling information stored in the database and generating reports relating to the presence of mobile telephones in the predefined area. Data retrieved from the database may be parsed by telephone user, by zone or cell, by time or date, etc. For instance, the present invention may provide a report showing every mobile telephone located in a selected cell, or showing each cell in which a particular mobile telephone was located, together with date/time information and mobile telephone user identification .

Moreover, cell information from the database may be accessed periodically so that the positioning of one or more mobile telephones may be monitored in substantially real time. In this way, the present invention may serve as a surveillance system. BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the system and method of the present invention may be obtained by reference to the following Detailed Description when taken in conjunction with the accompanying Drawings wherein:

Figure 1 is a block diagram of the present mobile communications system according to a preferred embodiment of the present invention; Figure 2 is a first flow chart illustrating a first set of operations of the mobile communications system according to the embodiment of Figure 1 ;

Figure 3 is a second flow chart illustrating a second set of operations of the mobile communications system according to the embodiment of Figure 1; and

Figure 4 is an exemplary report generated by the mobile communications system according to the preferred embodiment thereof .

DETAILED DESCRIPTION OF THE PREFERRED EXEMPLARY

EMBODIMENTS

The present invention will now be described more fully hereinafter with reference to the accompanying drawings in which a preferred embodiment of the invention is shown. This invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiment set forth herein. Rather, the embodiment is provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

Referring to Figure 1, there is shown a mobile communications system 1 according to a preferred embodiment of the present invention. Mobile communications system 1 preferably provides conventional voice and other communication to one or more mobile telephones 2 which are situated within the predefined area 3 served thereby. Predefined area 3 may preferably be the area within a building, compound or other relatively small geographical area.

In addition, mobile communications system 1 is capable of determining the position of one or more active mobile telephones 2 in predefined area 3 served thereby. The predefined area 3 is divided into a number of zones 4, with each zone 4 being further divided into one or more cells 5. For each cell 5 within predefined area 3, mobile communications system 1 includes a base station 6 corresponding thereto. Each base station 6 is associated with at least one distinct cell 5 such that mobile communications system 1 provides mobile telephone service to a mobile telephone 2 via the particular base station 6 corresponding to the cell 5 in which the mobile telephone 2 is located.

In providing conventional mobile telephone service, mobile communications system 1 further includes a switch 7 which controls telephone calls between one or more mobile telephones 2 and terminals in other telephone and/or data systems. Mobile communications system 1 may further include a radio exchange 8 which communicates with each base station 6, and a mobility server 9 which communicates directly with radio exchange 8 and switch 7 as is known in the art.

In a preferred embodiment of the present invention, each mobile telephone 2 preferably includes necessary software, hardware and/or firmware for transmitting an identification signal. The identification signal for each mobile telephone 2 preferably includes a unique code that is transmitted over a data channel . Mobile telephone 2 periodically transmits the identification signal. For example, mobile telephone 2 may transmit its identification signal every five seconds. It is understood, however, that the frequency with which mobile telephone 2 transmits the identification signal may vary and depend upon a variety of factors, such as channel bandwidth and desired degree of accuracy in tracking mobile telephone 2 within predefined area 3. Mobile telephone 2 preferably periodically transmits its identification signal whenever mobile telephone 2 is active and not involved in a speech communication. Each base station 6 is preferably capable of receiving the identification signal from mobile telephone 2 and forwarding the received identification signal to switch 7. Switch 7 preferably includes or is associated with a memory device 10 for storing data relating to the location of mobile telephone 2 within predefined area 3.

In order to provide a relatively accurate chronology of the position or movement of mobile telephone 2 within predefined area 3 , switch 7 records temporal information in memory device 10 relating to the positioning of mobile telephone 2. The temporal information may be subsequently retrieved from memory device 10 for review.

According to a preferred embodiment of the present invention, when mobile telephone 2 moves from one cell 5 to a new cell 5, the temporal information is stored in a database 11 in memory device 10 together with corresponding cell information. Specifically, upon reception of an identification signal from mobile telephone 2, switch 7 determines the current cell 5A for mobile telephone 2, i.e., the cell 5 from which mobile telephone 2 transmitted the identification signal. Upon determining the current cell 5A, switch 7 determines whether mobile telephone 2 has recently entered the current cell 5A, by comparing current cell 5A with the cell information stored in database 11 relating to the cell 5 from which mobile telephone 2 transmitted the identification signal immediately prior to the most recent transmission thereof. Switch 7 concludes that mobile telephone 2 recently entered the current cell 5A upon determining that current cell 5A does not match the cell information stored in database 11 relating to the cell 5 from which mobile telephone 2 transmitted the identification signal immediately prior to the most recent transmission thereof. Upon reaching such a conclusion, cell information and temporal information pertaining to the entry of mobile telephone 2 into current cell 5A are stored in database 11.

According to a preferred embodiment of the present invention, the temporal information stored in database 11 is preferably date and time information. In particular, switch 7 stores the date and time data to correspond to both the current cell 5A into which the mobile telephone 2 recently entered as well the cell 5 from which the mobile telephone exited to enter the current cell 5A. In this way, database 11 documents the total amount of time mobile telephone 2 spends in each cell 5.

Further, switch 7 preferably includes a timer 12 which is selectively activated and deactivated by switch 7. Timer 12 is initialized and begins to count when switch 7 determines that mobile telephone 2 has just recently entered a current cell 5A. Timer 12 is deactivated or stops counting when switch 7 determines that mobile telephone 2 is no longer transmitting its identification signal from the current cell 5A. This determination could result from mobile telephone 2 being inactive and/or turned off, or mobile telephone 2 exiting current cell 5A and entering a different cell 5. Upon deactivation of timer 12, the time period stored in timer 12 is stored in database 11, together with information pertaining to the corresponding current cell 5A.

Database 11 may be updated with current cell information and corresponding temporal information upon the occurrence of a handover operation in which mobile telephone 2 is in a speech or voice connection while roaming between two cells 5. In this case, switch 7 determines the new current cell 5A from which mobile telephone 2 is engaged in a speech connection, and updates database 11 with both the new current cell 5A and the date/time information corresponding thereto. Switch 7 additionally activates timer 12 upon the occurrence of a cell handover operation. Consequently, database 11 is suitably updated at all times when mobile telephone 2 is active. According to a preferred embodiment of the present invention, mobile communications system 1 may include computing element 13 having software for retrieving current cell and corresponding temporal information, and generating reports which document the whereabouts of mobile telephone 2. The reports may, for example, be in tabular form with entries thereof ordered by user, cell, date, time, etc. Mobile communications system 1 may further include external database 14 to which database 11 may be occasionally downloaded using computing element 13.

Further, computing element 13 may include software to substantially continuously or periodically access database 11, present a geographical image of predefined area 3, and depict the location of mobile telephone 2 therein based upon the current cell information for mobile telephone 2 stored in database 11. By periodically accessing regularly-updated database 11, mobile communications system 1 is capable of monitoring mobile telephone 2 in substantially real time.

The operation of a preferred embodiment of the present invention will be described with reference to Figure 2. In the event mobile telephone 2 is active and not involved in a speech connection, base station 6 receives an identification signal from a mobile telephone 2 at step 20. The base station 6 then forwards the identification signal to switch 7 at step 21. Next, at step 22 switch 7 identifies the particular mobile telephone 2 which transmitted the identification signal and determines the current cell 5A from which the identification signal was transmitted. The determination of the current cell 5A may be based upon determining which base station 6 forwarded the identification signal to switch 7 during step 21. Next, switch 7 determines at step 23 whether mobile telephone 2 recently entered current cell 5A. Switch 7 makes this determination by retrieving cell information from database 11 for the cell from which mobile telephone 2 transmitted the identification signal immediately prior to the most recent transmission thereof, and comparing the current cell 5A to the retrieved cell information. A favorable comparison shows that mobile telephone 2 has not recently entered the current cell 5A, and a disfavorable comparison shows the reverse to be true. In the event switch 7 determines that mobile telephone 2 recently entered current cell 5A, switch 7 stores at step 24 time and date information in database 11. The time information may be taken from the value of timer 12, which previously had been initialized and counting. The time and date information is stored in database 11 to correspond to the current cell 5A so as to document the entry of mobile telephone 2 therein.

Next, switch 7 determines at step 25 whether the identification signal received by base station 6 in step 20 is the start of a new series of periodic identification signals transmitted by mobile telephone 2. This step is performed in order to determine whether mobile telephone 2 had exited another cell 5 when entering current cell 5A or instead had been inactive immediately prior to being active and transmitting the identification signal therefrom. Switch 7 makes this determination by comparing the date and time information stored in database 11 during step 24 with date and time information which was most recently stored in database 11 for mobile telephone 2 prior to step 24. Based upon the comparison, if it is determined that the identification signal received by base station 6 during step 20 is part of an ongoing sequence of identification signals periodically transmitted by mobile telephone 2, then it is concluded that mobile telephone 2 had exited another cell 5 when entering the current cell 5A, and the date and time information is then stored in database 11 to correspond to the cell 5 from which mobile telephone 2 had exited in entering current cell 5A. In this way, database 11 includes information pertaining to both the entry and exit of mobile telephone 2 in cells 5 of the predefined area 3.

In the event switch 7 determines that the identification signal received by base station 6 during step 20 is the start of a new sequence of periodic transmissions by mobile telephone 2, then switch 7 concludes that mobile telephone 2 had previously been inactive before transmission from current cell 5A, and does not store any exit date and time information in database 11.

Next, timer 12 is initialized and activated at step 27 to begin counting. The value in timer 12 will then correspond to the amount of time mobile telephone 2 remains active within current cell 5A. Next, and/or in the event that switch 7 had determined during step 23 that mobile telephone 2 has not recently entered the current cell 5A, switch 7 awaits the next identification signal from mobile telephone 2. If switch 7 determines at step 28 that mobile telephone 2 has failed to transmit another identification signal at the next predetermined time, then it is concluded that mobile telephone 2 has become inactive. The value stored in timer 12 is then stored in database 11 at step 29 to indicate the time that mobile telephone 2 became inactive while in current cell 5A. Otherwise, step 29 is bypassed and the process is repeated over again for the reception of another identification signal from mobile telephone 2.

At any time or at a predetermined time, database 11 may be downloaded at step 30 to external database 14 (Figure 3) . Once downloaded, the cell information and corresponding temporal (date/time) information may be retrieved at step 31 from external database 14, parsed, and compiled to generate reports at step 32 regarding the presence of mobile telephone 2 within predefined area 3. The report may be parsed by the user of each mobile telephone 2, by the zone 4 or cell 5, etc. An exemplary report is shown in Figure 4. In addition, current cell information for mobile telephone 2 may be retrieved from database 11 at step 33, processed and displayed on computing element 13 at step 34 (Figure 3) . The display may illustrate a map of predefined area 3 showing the locations and boundaries of cells 5 and an up-to-date indication of each mobile telephone 2 therein. By continuously or periodically retrieving current cell information for mobile telephones 2 from database 11, such as retrieving cell information at the same frequency at which mobile telephones 2 transmit their respective identification signals to base stations 6, the positioning of mobile telephones 2 within predefined area 3 may be monitored and displayed in substantially real time. The invention being thus described, it will be obvious that the same may be varied in many ways . Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

Claims

WHAT IS CLAIMED IS:

1. A method for determining a position of a mobile telephone within a predefined area, comprising the steps of : periodically receiving identification information transmitted by a mobile telephone; determining the identity of the user of the mobile telephone based upon the received identification; determining a current sub-area from a plurality of sub-areas within the predefined area from which the mobile telephone most recently transmitted the identification information; selectively storing in memory the identity of the current sub-area from which the mobile telephone most recently transmitted the identification information; and selectively storing in memory temporal information relating to the reception of the identification information.

2. The method of claim 1, further comprising the step of : comparing the current sub-area from which the mobile telephone most recently transmitted the identification information to a sub-area from which the mobile telephone transmitted the identification information immediately prior to most recently transmitting the identification information; wherein the step of storing in memory temporal information comprises the step of storing in memory the temporal information upon an affirmative determination that the current sub-area from which the mobile telephone most recently transmitted the identification information is different from the sub-area from which the mobile telephone transmitted the identification information immediately prior to the most recent transmission of the identification information.

3. The method of claim 2, wherein the step of storing in memory temporal information comprises the step of: storing in memory time and date information relating to the reception of the identification information most recently transmitted by the mobile telephone.

4. The method of claim 3, wherein: the time and date information is stored in memory to correspond to the current sub-area from which the mobile telephone most recently transmitted the identification information and to the sub-area from which the mobile telephone transmitted the identification information immediately prior to the most recent transmission of the identification information from the current sub-area.

5. The method of claim 1, further including the steps of: comparing the current sub-area from which the mobile telephone most recently transmitted the identification information to a sub-area from which the mobile telephone transmitted the identification information immediately prior to the most recent transmission of the identification information; and storing in memory the sub-area from which the mobile telephone transmitted the identification information immediately prior to the most recent transmission of the identification information, upon an affirmative determination that the current sub-area from which the mobile telephone most recently transmitted the identification information is different from the sub-area from which the mobile telephone transmitted the identification information immediately prior to the most recent transmission by the mobile telephone from the current sub-area.

6. The method of claim 1, further comprising the step of: comparing the current sub-area from which the mobile telephone most recently transmitted the identification information to a sub-area from which the mobile telephone transmitted the identification information immediately prior to the most recent transmission of the identification information; wherein the step of storing in memory the current sub-area comprises the step of storing in memory the current sub-area from which the mobile telephone most recently transmitted the identification information upon an affirmative determination that the current sub- area from which the mobile telephone most recently transmitted the identification information is different from the sub-area from which the mobile telephone transmitted the identification information immediately prior to the most recent transmission thereof.

7. The method of claim 1, further comprising the step of : accessing from memory the stored temporal information relating to the reception of the identification information.

8. The method of claim 7, wherein: the memory is accessed in substantially real time during the step of accessing.

9. The method of claim 1, further comprising the steps of: retrieving the identity of the current sub-area from memory; and displaying the identity of the current sub-area accessed from memory.

10. The method of claim 9, wherein: the identity of the current sub-area is displayed in substantially real time during the step of displaying.

11. The method of claim 1, further comprising the steps of: counting a period of time during which the mobile telephone transmits the identification information from the current sub-area; and storing the counted period of time in memory following the mobile telephone no longer transmitting the identification information from the current sub- area.

12. A system for determining a position of a mobile telephone within a predetermined area that is partitioned into a plurality of cell areas, comprising: at least one mobile telephone which periodically transmits an identification signal; a plurality of base stations, each base station corresponding to at least one distinct cell area and communicatable with the mobile telephone when the mobile telephone is within the respective cell area; a switching device, communicatable with each of the base stations, for determining the current cell area in which the mobile telephone is positioned, generating temporal information relating to the transmission of the periodic identification signal, and selectively storing the current cell area and temporal information in memory; and processing means for selectively retrieving from memory the stored cell area information and the temporal information relating the mobile telephone for presentation .

13. The system of claim 12, wherein: the switching device compares the current cell area from which the mobile telephone most recently transmitted the identification information to a cell area from which the mobile telephone transmitted the identification information immediately prior to the most recent transmission of the identification information, and stores in memory the temporal information upon an affirmative determination that the current cell area from which the mobile telephone most recently transmitted the identification information is a different cell area from the cell area from which the mobile telephone transmitted the identification information immediately prior to the most recent transmission of the identification information.

14. The system of claim 12, wherein: the temporal information comprises time and date data relating to the reception by a base station of the identification information most recently transmitted by the mobile telephone.

15. The system of claim 12, wherein: the time and date information is stored in memory so as to correspond to the time of entry by the mobile telephone into the current cell area from which the mobile telephone most recently transmitted the identification information, and to the time of exit by the mobile telephone from the cell area from which the mobile telephone transmitted the identification information immediately prior to the most recent transmission of the identification information from the current cell area.

16. The system of claim 12, wherein: the switching device stores in memory the identity of the mobile telephone together with the temporal information.

17. The system of claim 12, wherein: the switching device includes a timer which measures a period of time during which the mobile telephone periodically transmits the identification information from the current cell area.

18. The system of claim 17, wherein: the measured period of time during which the mobile telephone periodically transmits the identification information from the current cell area is stored in memory.

19. The system of claim 18, wherein: the measured period of time is stored in memory following the switching device determining that the mobile telephone ceased periodically transmitting the identification information from the current cell area.

20. The system of claim 12, wherein: the processing means includes a displaying means for presenting the cell area information stored in memory relating to the mobile telephone.

21. The system of claim 20, wherein: the displaying means presents a geographical image of the predetermined area and a depiction of the current location of the mobile telephone in the geographical image.

22. The system of claim 20, wherein: the displaying means displays the cell information and the temporal information of the mobile telephone stored in memory in a tabular form.

23. The system of claim 12, further comprising: an external database for selectively downloading the cell area information and the temporal information relating to the mobile telephone thereto.

24. The system of claim 12, wherein: the predetermined area comprises a building which is partitioned by the plurality of cell areas.

25. A system for locating a mobile telephone within a building or confined area which is partitioned into a number of cell areas, comprising: at least one mobile telephone which periodically transmits an identification signal corresponding thereto; a switching device for controlling telephone calls to and from the mobile telephone, receiving the identification information transmitted thereby, determining the current cell area from which the mobile telephone most recently transmitted the identification information and temporal information relating thereto, and selectively storing current cell area information and the temporal information in memory; and a processing device for retrieving the current cell area information and the temporal information from memory and presenting to an operator of the processing device.

26. The system of claim 25, further including: a plurality of base stations, each base station being associated with at least one distinct cell area for communication between the mobile telephone and the switching device; the switching device determines the current cell area from which the mobile telephone most recently transmitted the identification information based upon the particular base station which communicated to the switching device the identification information most recently transmitted by the mobile telephone.

27. The system of claim 25, wherein: the temporal information determined by the switching device comprises date and time information corresponding to the time the mobile telephone began periodically transmitting the identification information from the current cell.

28. The system of claim 25, wherein: the temporal information determined by the switching device comprises date and time information corresponding to the time the mobile telephone stopped periodically transmitting the identification information from the current cell.

29. The system of claim 25, wherein: the switching device further comprises a timer being activated when the switching device determines that the mobile telephone begins periodic transmission of the identification information from the current cell, and deactivated when the switching device determines that the mobile telephone ceases periodic transmission of the identification information therefrom, the value of the timer corresponding to the temporal information.

30. The system of claim 25, wherein: the switching device stores the identification information in memory.

31. The system of claim 25, wherein: the processing device presents to the operator thereof the current cell area information in substantially real time.