USOO730524.4B2
`
`(12) United States Patent
`Blomqvist et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 7,305,244 B2
`Dec. 4, 2007
`
`(54) METHOD FOR ACTIVATING A
`LOCATION-BASED FUNCTION, A SYSTEM
`AND A DEVICE
`
`75
`(75) Inventors: the legities, (FI);
`s
`p
`(73) Assignee: Nokia Corporation, Espoo (FI)
`c
`-
`0
`(*) Notice:
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 99 days.
`(21) Appl. No.: 10/762,589
`
`(22) Filed:
`
`Jan. 21, 2004
`
`(65)
`
`Prior Publication Data
`US 2004/O180674 A1
`Sep. 16, 2004
`
`Foreign Application Priority Data
`(30)
`Jan. 21, 2003
`(FI)
`.................................. 2003OO90
`(51) Int. Cl.
`(2006.01)
`H04O 7/20
`(52) U.S. Cl. ............................... 455/456.5:455/414.1;
`455/414.2:455/456.1; 455/456.2:455/456.3:
`455/457; 455/466; 701/207: 701/213: 701/214;
`701/216:342/357.01: 342/357.06:342/357. 12
`(58) Field of Classification Search ............. 455/414.1,
`455/414.2, 456.1-457, 466; 701/207,213,
`701/214, 216; 342/357.01, 357,06,357. 12
`See application file for complete search history.
`References Cited
`
`(56)
`
`U.S. PATENT DOCUMENTS
`
`5,982,324. A * 11/1999 Watters et al. ......... 342,357.06
`6,014,090 A
`1/2000 Rosen et al. ................ 340,905
`6,061,561 A *
`5/2000 Alanara et al. .......... 455/4.56.1
`6,108,533 A * 8/2000 Brohoff ............
`... 455,414.3
`6,351,647 B1
`2/2002 Gustafsson ................. 455,466
`6.424,840 B1* 7/2002 Fitch et al. .......
`... 455,456.1
`6,477,363 B1 * 1 1/2002 Ayoub et al. ............ 455,404.2
`6,496.776 B1* 12/2002 Blumberg et al. .......... TO1,213
`6,571,279 B1* 5/2003 Herz et al. .................. 709/217
`6,580,914 B1* 6/2003 Smith ........
`... 455,456.6
`6,728,528 B1
`4/2004 Loke .......................... 455,318
`6,731,612 B1*
`5/2004 Koss .........
`... 370,310
`6,772,213 B2 *
`8/2004 Glorikian .......
`... TO9,228
`6,789,102 B2*
`9/2004 Gotou et al. ................ TO9,203
`9/2004 Joyce et al. ........... 340,995.24
`6,798.358 B2*
`
`(Continued)
`FOREIGN PATENT DOCUMENTS
`
`EP
`
`1045,609
`
`10, 2000
`
`(Continued)
`Primary Examiner Steve M. D’Agosta
`(74) Attorney, Agent, or Firm Ware, Fressola, Van Der
`Sluys & Adolphson
`
`(57)
`
`ABSTRACT
`
`A method for activating a location-based function, at least
`one item of position data is determined for the function as a
`condition for activating the function. A device in a wireless
`communication network examines at least one property of
`the network to decide whether positioning of the device (1)
`is conducted. Likewise, a system may provide a location
`based function, for which at least one item of position data
`is determined as a condition for activating the function. A
`program in which the method is applied is also provided.
`
`5,963,861. A * 10/1999 Hanson ................... 455,456.1
`
`9 Claims, 4 Drawing Sheets
`
`
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`Page 1 of 13
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`SAMSUNG EX-1033
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`US 7,305,244 B2
`Page 2
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`6,922,567
`6,944,465
`6,957,076
`6,970,871
`6,993,326
`7,035,647
`7,050,816
`7,107,038
`2002fO164999
`2003/O119530
`
`
`
`U.S. PATENT DOCUMENTS
`B1* 7/2005 Rydbeck ...............
`... 455,456.3
`B2 * 9/2005 Spain et al. ...
`... 455,456.1
`B2 * 10/2005 Hunzinger ..
`455,456.3
`B1 * 1 1/2005 Rayburn .....
`B2
`1/2006 Link et al. ..
`B2
`4, 2006 de Verteuil ....
`B2
`5, 2006 Fukui et al. ...
`B2
`9, 2006 Fitch et al. ...
`Al 1 1/2002 Johnson ......
`Al
`6/2003 Rankin .................
`
`- - - - - 707/10
`
`455,414.1
`... 455,456.1
`... 455,456.1
`... 455,404.2
`... 455,456
`
`- - - - - - 455,456
`
`2004,0008138 A1*
`
`1/2004 Hockley et al. ....... 342,357.09
`
`FOREIGN PATENT DOCUMENTS
`
`EP
`
`WO
`
`WO
`WO
`WO
`WO
`
`1189474
`O113662
`O 137601
`O217654
`O3O45100
`O3O96735
`
`3, 2002
`2, 2001
`5, 2001
`2, 2002
`5, 2003
`11/2003
`
`* cited by examiner
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`Page 2 of 13
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`U.S. Patent
`U.S. Patent
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`Dec. 4, 2007
`Dec. 4, 2007
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`US 7,305,244 B2
`US 7,305,244 B2
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`Sheet 1 of 4
`Sheet 1 of 4
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`Fig.1a
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`U.S. Patent
`U.S. Patent
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`Dec. 4, 2007
`Dec. 4, 2007
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`US 7,305,244 B2
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`U.S. Patent
`U.S. Patent
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`Dec. 4, 2007
`Dec. 4, 2007
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`Sheet 3 of 4
`Sheet 3 of 4
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`US 7,305,244 B2
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`U.S. Patent
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`US 7,305,244 B2
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`1.
`METHOD FOR ACTIVATING A
`LOCATION-BASED FUNCTION, A SYSTEM
`AND A DEVICE
`
`CROSS-REFERENCE TO RELATED
`APPLICATIONS
`
`This application claims priority under 35 USC S 119 to
`Finnish Patent Application No. 20030090 filed on Jan. 21,
`2003.
`
`10
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`FIELD OF THE INVENTION
`
`15
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`The present invention relates to a method for activating a
`location-based function, in which at least one item of
`position data is determined for the function as a condition for
`activating the function, the device being used in a wireless
`communication network in which signals are transmitted.
`The invention also relates to a system comprising determi
`nation means for determining a location-based function, in
`which at least one item of position data is determined for the
`function as a condition for activating the function, process
`ing means for activating the location-based function in a
`device, and a wireless communication network comprising
`at least one transmitter for transmission of signals. More
`25
`over, the invention relates to a device comprising determi
`nation means for determining a location-based function, in
`which at least one item of position data is determined for the
`function as a condition for activating the function, process
`ing means for activating the location-based function in a
`device, and wireless communication means for setting up a
`data network connection to a wireless communication net
`work. The invention also relates to a program containing a
`group of machine-executable program commands for pre
`senting messages in a device, and at least one location-based
`condition for presenting the message is determined in the
`message, said program being intended to be executed in a
`device used in a communication network in which signals
`are transmitted.
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`BACKGROUND OF THE INVENTION
`
`Several applications have been developed that contain a
`location-based condition determined for a message for the
`presentation of the message. Such messages are for example
`regional advertisements that can be transmitted to a device
`carried by the user, and when the user arrives to a certain
`location, for example in the vicinity of a store, a restaurant,
`a service station, or the like, this is indicated in the device
`of the user. The person in question may have determined
`conditions for presenting different messages in his or her
`device, wherein when he or she approaches a location in
`relation to which he or she has determined a message to be
`presented, said message is presented in the device. The
`person may determine for example a reminder to visit a
`certain hardware store, wherein when the user approaches
`said hardware store, this is indicated in the device of the
`USC.
`To enable the above-presented arrangements, positioning
`must be conducted in the device at intervals so that the
`location of the device is known also when the user is
`moving. In solutions of related art, positioning must be
`conducted relatively often, several times a minute, or even
`tens of times a minute, so that the positioning is Sufficiently
`accurate and occurs in real time. Typically positioning is
`conducted by means of a positioning receiver arranged for
`this purpose, said receiver determining its location on the
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`basis of the signals transmitted by the satellites of the
`positioning system. Positioning systems that can be men
`tioned in this context are for example the GPS system and
`the GLONASS system. Applications have also been devel
`oped in which the positioning is conducted for example by
`means of the base stations of a mobile communication
`network, or a wireless local area network. In some cases the
`mobile communication network performs the positioning of
`the device and transmits information thereon to the device.
`One of the drawbacks in Such continuous positioning is
`for example that it increases the power consumption of the
`device, which, especially in portable devices, can restrict the
`availability of positioning and shorten the operating time of
`the device. Furthermore, especially the positioning informa
`tion obtained from the mobile communication system may
`be subject to charge, wherein positioning may be expensive.
`
`SUMMARY OF THE INVENTION
`
`It is an aim of the present invention to provide an
`improved method and system for performing location-based
`functions (for example presenting messages) in a device.
`The invention is based on the idea that at least one property
`of a wireless communication network is monitored, wherein
`a change in at least one property of the monitored wireless
`communication network is used as a condition for perform
`ing the positioning. In a solution according to a first pre
`ferred embodiment of the invention, the positioning is
`always performed when it is detected that the device has
`moved to the area of another cell. This can be detected on the
`basis of the changes in the cell identifier. In the solution
`according to a second preferred embodiment of the inven
`tion, one or several cell identifiers are determined, wherein
`when the device enters the area of Such a cell, positioning is
`performed. In a method according to yet another preferred
`embodiment of the invention, at least one property, such as
`signal strength and/or timing of a signal transmitted in a
`wireless communication network is monitored, wherein a
`change in the monitored property either as such or together
`with the cell identifier, determines whether positioning is
`conducted or not. To put it more precisely, the method
`according to the present invention is primarily characterized
`in that at least one property of a wireless communication
`network is monitored in the device to decide whether
`positioning of the device is conducted. The system accord
`ing to the present invention is primarily characterized in that
`the device comprises monitoring means for monitoring at
`least one property of a wireless communication network,
`and determination means in which the property to be moni
`tored is arranged to be used to decide whether positioning of
`the device is conducted. The device according to the present
`invention is primarily characterized in that the device com
`prises monitoring means for monitoring at least one property
`of a wireless communication network, and determination
`means in which the property to be monitored is arranged to
`be used to decide whether positioning of the device is
`conducted. Furthermore, the program according to the
`present invention is primarily characterized in that the
`program also comprises machine-executable program com
`mands for monitoring at least one property of a wireless
`communication network to decide whether positioning of
`the device is conducted.
`The present invention shows remarkable advantages over
`solutions of prior art. When the method according to the
`invention is applied, it is not necessary to perform the
`positioning as often as in solutions of the prior art, because
`the criterion for performing the positioning is relatively
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`US 7,305,244 B2
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`reliable information based on the fact that the user has
`indeed moved from a previous location to another location.
`Thus the total power consumption of the device can be
`reduced. The reduced need to perform positioning reduces
`the loading of the processor of the device, wherein more
`capacity is available for use for the needs of other applica
`tions. Furthermore, if the positioning utilized in the device
`is based on the use of a service that is subject to charge,
`savings in the positioning costs are attained by means of the
`method according to the invention. When applied in net
`work-assisted systems, it is also possible to reduce the
`loading of the network by means of the invention.
`Another advantage attained by means of the method
`according to a first preferred embodiment of the invention is
`that the positioning is more reliable because the dependency
`of the positioning on the network is less significant than in
`situations where solutions of the prior art are applied. The
`reason for this is that the positioning is performed primarily
`in the device itself.
`When the method according to the second preferred
`embodiment of the invention is applied, it is not necessary
`to show the cell identifier in the device for the user or for the
`application that has requested for a location-based reminder.
`Thus, it is possible to apply the method also in connection
`with such networks in which it is desired to conceal the cell
`identifier.
`
`DESCRIPTION OF THE DRAWINGS
`
`In the following, the invention will be described in more
`detail with reference to the appended drawings, in which
`FIG. 1a shows an exemplary situation, in which the
`method is applied,
`FIG. 1b shows another exemplary situation, in which the
`method is applied,
`FIG. 2 shows a system according to a preferred embodi
`ment of the invention in a simplified block diagram, and
`FIG. 3 shows a device according to a preferred embodi
`ment of the invention in a simplified block diagram.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`4
`the operating range is not regular, but varies for example as
`a result of weather conditions, the shape of the terrain,
`radiation patterns of the antennas and other environmental
`factors.
`In FIG. 1, a broken line D also illustrates as an example
`the possible travel path of user of the device 1 towards the
`target L1.
`Let us assume that in the system according to FIG. 2, the
`device is logged in, i.e. communicating with the communi
`cation network 2. Such as a mobile communication network
`via one or several base stations 2.1. The base stations, in
`turn, are connected to a base station Switching centre 2.2 or
`the like. In the system according to FIG. 1a, the base station
`Switching centres are connected to a network centre, 2.3,
`Such as a mobile station Switching centre. Although in this
`description a mobile station Switching centre is used as an
`example of the communication network 2, it should be
`evident that the invention can also be applied in connection
`with other wireless communication networks, such as wire
`less local area networks (not shown).
`It is well known that base stations 2.1 are used in wireless
`local area networks, via which base stations the networks are
`connected to the terminals moving in the area of the net
`work, Such as mobile phones or portable computers
`equipped with a transmitter/receiver of the wireless local
`area network. Such base stations 2.1 are also called serving
`base stations. For each base station 2.1 an identifier (ID) is
`determined. The area determined by the radius of operation
`of one base station is also called a cell, wherein the term cell
`identifier is in the description hereinbelow used for this base
`station identifier. In the example system of FIG. 2, different
`cell identifiers are marked with ID1-ID5, but in practice, the
`different presentation modes of the identifiers can be differ
`ent in different applications.
`During the function of the device 1 for example the
`processor 1.2 of the device executes a program in which the
`method according to the present invention is applied. In the
`program, at least one property of the wireless communica
`tion network and changes in the same are monitored. In the
`following, cell identifiers and changes in them are used as a
`non-restrictive example of Such a property. This can be
`advantageously implemented in Such a manner that signals
`transmitted by the serving base station 2.1 are received by
`the receiver 1.3, and the information transmitted in the
`signal is presented. This information contains the cell iden
`tifier, which is thus transmitted to the program executed in
`the processor. Thus, the program compares the cell identifier
`according to the previously stored serving base station with
`the cell identifier of the currently received cell identifier. If
`they match, it can be determined that the cell has not
`changed, and it is not necessary to conduct positioning.
`However, in such a situation where the cell identifier has
`changed, positioning is started. Thus, the processor 1.2
`activates a positioning receiver 1.4 in connection with the
`device 1. This positioning receiver 1.4 is for example a
`positioning receiver according to the GPS positioning sys
`tem known as such. The operation of Such a positioning
`receiver is of prior art known by anyone skilled in the art,
`wherein it is not necessary to discuss it in more detail in this
`COInteXt.
`It is, however, possible to perform the positioning by
`means of another method, for example by means of a base
`station based positioning method. Thus, a signal transmitted
`by three or several base stations 2.1 is received in the device
`1, and on the basis of the differences in the mutual reception
`times of the signals and the known location coordinate
`information of the base stations 2.1 it is possible to perform
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`In the exemplary situation of FIG. 1a, the user has
`determined a location-based function, Such as a reminder in
`a device 1 for example by means of a keyboard 1.5 (FIG. 3).
`The function can be for example a picture message, a text
`message, a sound message or a combination of these,
`starting of a program or a service in the device 1, or a
`corresponding function. The determination of the function
`contains for example coordinate information or the like by
`means of which the position data activating the function can
`be determined with sufficient accuracy. The position data
`can also contain information for example on the radius,
`wherein when the user arrives in the area determined by the
`coordinates and the radius, a predetermined function is
`performed, for example a message relating to the reminder
`is presented in the device 1. In FIGS. 1a and 1b, the
`reference numeral L1 represents one example location to
`which the location-based function relates. The information
`on the function is advantageously stored in the memory 1.1.
`of the device 1 (FIG. 3), but the invention can also be applied
`in Such a manner that at least part of the information relating
`to the function is stored in the communication network 2.
`The ellipses drawn around the base stations 2.1 illustrate
`the operating range of the base stations, i.e. a so-called cell.
`It is, however, evident that in practice the size and shape of
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`a calculation to determine the location of the device 1 in a
`manner known as such. The base station based positioning
`can also be conducted in the communication network in Such
`a manner that a signal transmitted by a transmitter 1.8 of the
`device 1 is received by at least three base stations 2.1. Also
`in this situation the location of the device 1 can be calculated
`by means of the reception times of the signal at different
`base stations and the known location coordinate information
`of the base stations.
`After the location of the device 1 has been determined, it
`is examined whether the device 1 is in the vicinity of a
`location complying with a stored function performance
`condition. This is implemented in the device 1 advanta
`geously in Such a manner that the location coordinates and
`possible distance information, such as the radius, are exam
`ined in the function information stored in the memory 1.1.
`If the determined location is in the area determined by a
`performance condition of the function, the necessary mea
`Sures are taken to perform the function. This can be advan
`tageously implemented in Such a manner that a so-called
`reminder service library implementing the reminder service
`as well as an application that utilizes the reminder service
`library to perform a function, for example to present a
`reminder in text format for the user are established in the
`device 1. Thus, the application calls for Such a function in
`the reminder service library by means of which the appli
`cation can determine the location in which the reminder
`service library will provide the application with information
`on the arrival in the determined location. When the appli
`cation has received information on the arrival in the deter
`mined location, the application implements the determined
`function, for example presents a message in text format.
`Thus, said text is formed on the display 1.6. Similarly, if the
`message in question is another visual message, this message
`is formed on the display 1.6. Furthermore, if the message in
`question is a Sound message, this sound message is trans
`mitted to a speaker/earpiece 1.7.
`It is also possible to determine acknowledgement data for
`the message, or data on the display time of the message and
`possibly also data on the repetition interval of the message.
`Thus, the visual message remains on the display 1.6 until the
`user acknowledges it or the display time expires. The audio
`message, in turn, is repeated advantageously at intervals
`determined by the repetition interval, until the user acknowl
`edges the message or the display time expires.
`Other functions to be mentioned in this context that can be
`activated on the basis of the location are starting of a
`program, changing the settings of a device, for example
`changing the user profile in a mobile station, re-configura
`tion, or a security function. The user for example wishes to
`silence his or her mobile station when arriving to a certain
`location, turn off the mobile station for example when
`arriving to an airport, etc. It should be evident that the
`afore-described details only represent some possible
`examples, but the invention can also be applied in imple
`menting numerous other functions on the basis of the
`location. Furthermore, the invention can be applied to imple
`ment various services. Non-restrictive examples that can be
`mentioned in this context are informative services and
`security services.
`By means of the invention it is possible to implement for
`example Such an informative service in which a person
`wishes to receive a message when his or her acquaintance
`has arrived to a certain location, for example his or her
`home. Thus, the person utilizes his or her device (not shown)
`to transmit a function determination to the device 1 of his or
`her acquaintance, in which the device of the acquaintance is
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`requested to transmit information on the arrival of the device
`1 to a predetermined location. When the device 1 has
`received the function determination, it starts executing the
`method according to the invention to activate a location
`based function. Thus, when the device 1 arrives to a deter
`mined location, the device 1 transmits information thereon
`to the device of said person, in which the arrival of the
`monitored device to the predetermined location is indicated.
`An example of a security service that can be mentioned is
`the monitoring of the movement of a person. Thus, the
`person carries a device 1 according to a preferred embodi
`ment of the present invention in which the position condi
`tions of the location-based functions are monitored in the
`manner presented in this description. When said person
`arrives to a certain location or leaves a predetermined
`location or area, information thereon is transmitted from the
`device of the person to the monitoring device. Thus, a
`function, Such as an alarm is activated in the monitoring
`device to give information on the movement of the person
`that is being monitored. Companies providing guarding
`services, and transportation services of valuable goods can
`also apply the present invention for example in monitoring
`the movement of guards and transportations of valuable
`goods for example in the following manner. The device
`according to the invention accompanies the guard or the
`transportation of valuable goods, and one or several loca
`tion-based functions are determined in the device. Such a
`function is for example sending a message to the monitoring
`device in predetermined locations. Thus, the arrival of the
`monitored device is detected by the monitoring device.
`Furthermore, it is possible to determine information indi
`cating how long it will probably take to move from one
`location to another, wherein the delaying of a location-based
`message can be an indication that the movement of a guard
`or a transportation of valuable goods has not proceeded
`normally, and it is possible to start the necessary actions to
`determine the situation, for example to call help to the
`estimated problem location.
`FIG. 1b shows another example situation in which the
`method according to a preferred embodiment of the inven
`tion is applied. Also in this situation, position data is
`determined in the location-based function. Advantageously
`at least this position data is transmitted to the communica
`tion network 2, in which it is determined (for example in a
`network centre 2.3) in the area of which cell or cells this
`location is situated. Information on the identifiers of such a
`cell or cells is transmitted to the device 1, in which the
`information is stored into the memory 1.1 for example into
`the information of said location-based function. In the
`device 1, the changing of the cell identifier is monitored as
`disclosed hereinabove in connection with the description of
`the method according to the first embodiment of the inven
`tion. At that stage when the serving base station changes, i.e.
`the cell identifier changes, the device 1 examines the infor
`mation on the location-based functions on the basis of the
`new cell identifier. If one or several cell identifiers that have
`been determined for a location-based function match with
`the cell identifier of the new serving base station, i.e. the
`device 1 is probably in the vicinity of such a location in
`which the execution of a location-based function is deter
`mined, positioning is conducted. At that stage when the
`positioning shows that the device 1 is in the area determined
`for said location-based function, said location-based func
`tion is conducted.
`In the above-presented preferred embodiments of the
`invention, it is necessary for the device 1 to perform
`positioning and to examine the realization of the perfor
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`mance condition of the function only when the cell identifier
`changes. In the method according to yet another embodi
`ment of the invention, steps are taken that differ slightly
`from the process described above, the basic idea, however,
`relating to the examination of the changes in the cell 5
`identifier. In this embodiment, positioning is repeated at
`intervals at that stage when the device 1 has arrived suffi
`ciently close to the determined location or in the area of such
`a cell in which the location is situated. If this embodiment
`is applied in connection with the first preferred embodiment 10
`of the invention, the following steps are advantageously
`taken. Positioning is initiated always when the cell identifier
`changes. At that stage when the positioning indicates that the
`device 1 is in the vicinity of a position condition determined
`for a predetermined function, positioning is repeated at 15
`intervals, until the device 1 is positioned sufficiently close to
`the location according to the position condition of the
`function, or has moved further away from said location.
`When this embodiment is applied in connection with the
`second preferred embodiment of the invention, the follow- 20
`ing steps are advantageously taken. Positioning is not started
`immediately when the cell identifier changes, but the cell
`identifier is also compared with the stored cell identifiers.
`Thus, positioning and its repetition are not initiated until the
`device 1 has arrived to the area of such a cell in which the 25
`location according to a function is situated.
`The device 1 does not necessarily move towards the
`location according to the position condition, but starts to
`move further away from the same. In Such a situation the
`repetition of the positioning advantageously ceases and a 30
`shift to the act of examining the changing of the cell
`identifier takes place. The receding can be detected either on
`the basis of the determined location of the device 1 and the
`distance between the position condition or on the basis of the
`changing of the cell identifier.
`In this preferred embodiment it is possible to determine a
`constant repetition interval of positioning or Such a repeti
`tion interval that when the device moves closer to a location
`according to the position condition, the performance interval
`of positioning is shortened, and correspondingly, when the 40
`device 1 diverges from the location according to the position
`condition, the positioning interval is extended.
`As was mentioned above, the cell identifier is only one of
`the properties of the wireless communication network,
`changing of which can be utilized in the present invention to 45
`estimate the necessity of positioning. Other Such properties
`relating to the wireless communication network that can be
`monitored in the device 1 are for example the signal strength
`of the base station or base stations and information relating
`to the timing of signals (for example TA, Timing Advance). 50
`Thus, in a preferred embodiment of the invention, it is
`possible to reduce the need for positioning in the following
`manner. A signal-dependent coefficient of the serving base
`station, such as signal strength, is measured at intervals in
`the receiver 1.3 of the device 1. If the signal strength does 55
`not change significantly during Successive measurements, it
`can be assumed that the device 1 has hardly moved, and it
`is not necessary to perform positioning. However, if the
`signal strength changes, irrespective of that whether the cell
`identifier has changed or not, it can be assumed that the 60
`device 1 has moved. Thus, it is possible to conduct posi
`tioning. On the other hand, the measurement of the signal
`strength can be restricted to be used only in the area of such
`a cell to which a location-based function relates. Thus, the
`device 1 monitors the changing of the cell identifier as 65
`presented earlier in this description. Only at that stage when
`the device 1 is in the area of such a cell to which a
`
`35
`
`US 7,305,244 B2
`
`8
`location-based function relates, the results of a signal
`strength measurement, a signal timing measurement or the
`like are utilized to estimate whether the device 1 has moved
`significantly, and whether it is necessary to conduct new
`positioning.
`Furthermore, it is possible to determine a threshold value,
`which must be exceeded by the change before the position
`ing is started. Thus, Small and possibly short-time alterations
`in the monitored property do not cause unnecessary posi
`tioning.
`In some cases, when the device 1 moves especially further
`away from the base stations 2.1, the serving base station may
`change relatively often. In Such a situation the changing may
`occur in Such a manner that for example two or three serving
`base stations alternate, depending for example on the signal
`conditions and terrain obstacles between the base stations
`2.1 in question and the device 1. In a method according to
`a preferred embodiment of the invention, it is examined in
`connection with the changing of the cell identifier, whether
`said serving base station has been a serving base station
`already a moment before. If this is the case, it can be decided
`that positioning is not necessary, because it is likely that the
`device 1 has not moved closer to a location according to a
`position condition of any reminder. In connection with the
`change, it is also possible to examine how long a time has
`passed from the preceding occasion when the base station
`functioned as a serving base station for said device 1. If a
`period of time shorter than the determined time limit has
`passed, it is possible to make a decision that positioning is
`not necessary. Similarly, if a period of time longer than the
`predetermined time limit has passed, positioning is con
`ducted.
`When the method according to a first preferred embodi
`ment