ES2589577T3 - Method and equipment for locating mobile units that track another - Google Patents

Abstract

Method for providing the location of a portable mobile remote unit, PRU (501,510), associated with a telecommunications network comprising: I) obtaining geographic boundary information in the network within which the location of the PRU should be disclosed; Ii) request the location of PRUs within said geographical limit, Iii) obtain the location of a PRU within the network and determine if the PRU is within said geographical limit; Iv) send the location of the PRU to the network after the determination that the PRU is within said geographical limit.

Description

DESCRIPTION

Method and equipment for locating mobile units that track another

 5

Background of the invention

[0001] This invention relates to telecommunication services and systems, specifically such services and systems that transmit the location of a mobile unit.

 10

[0002] The wireless industry is currently moving towards the provision for the general public of a wide range of location-based services.

Such services will include utilization of the location of a portable remote subscriber unit to channel a wide range of location-based services to the subscriber.

For this type of service to be successful, the remote unit must be able to obtain and send its location information to other communication objectives of the network requesting such information.

[0003] In the relevant prior art such as US 5,689,245, Noreen and al, the location of a remote unit is used to execute specific location instructions transmitted to the remote unit.

 twenty

[0004] In Bird, US 5,418,537, a missing vehicle is located through the use of a GPS receiver mounted on the vehicle.

When the vehicle is missing, a search request is transmitted by the vehicle location center.

After receiving the transmitted message, the vehicle resolves and transmits its location to the service center. 25

[0005] In Buss, US 5,539,395, a remote unit is presented by which the unit selects and displays messages coinciding with the location of the remote unit.

The network provides the unit with messages that have a location signal.

If the location signal collected by the unit is within the current location of the unit, the message is displayed, otherwise it is kept in memory for display at the appropriate location.

[0006] In Chapman, US 5,504,491, a global state and positioning report system is described.

A remote unit obtains its global location and updates the network with status information and location information as necessary. 35

Such status information may include an emergency condition or relevant condition of the remote unit required by the network.

[0007] In Fomukong and al, US 5,918,159 a location report satellite search system with optional location report lock is disclosed. 40

In that invention, a remote mobile unit obtains its location information and provides that information through the network to other units in the network requesting the information.

The provision of such location information is made based on authorization information provided and routinely updated by the remote unit.

 Four. Five

[0008] The prior art Lemelson et al. US 5,731 785 inhibits pre-authorized network communication units from access to the location of a mobile device by entering an inhibition code in the mobile device to cut off the transmission of location signals from the mobile device to the network.

[0009] In all the inventions described above, the location of the remote unit is used by the system.

The deployment of location services could be quite beneficial for the general public if it is implemented safely.

In today's market, these types of mobile units are usually small, compact and lightweight.

These devices could be easily hidden to reveal the location of a mobile user without the user's knowing or authorizing the disclosure of their location.

Most wireless consumers may not want to disclose their location to the network or to the general public and the thought of being tracked by a clandestine unit hidden in an object such as a car or luggage to reveal the location of an individual would be unacceptable for the public in general.

The risk of abuse clearly exists and should be handled appropriately by wireless vendors. 60

In U.S. Patent 5,918,159 that provides authorization for location reports, it would be almost impossible for the network to prevent a hidden location report unit to provide the location of an individual that is tracked, since abuse is occurring.

Therefore there is a need for location reporting devices in a specific geographic region to reveal their location upon request. 65

In situations where a user is being tracked, the network would be able to determine which units are

tracking the user by asking for the location of remote units within a specific radius of the user or tracked unit.

The techniques required to provide the above result are described in the invention.

[0010] Whenever a mobile user is abandoned and requires immediate help, there may be another mobile part not too far from the user's location.

The mobile user may not be aware of the presence of the other mobile party in that geographic location.

When seeking the location of portable remote units (PRU) within the abandonment area, an anguished subscriber could immediately seek help at that location.

If the prescribed limit specified by the mobile user exceeds prespecified limits, the network may divide that geographic area 10 as described hereafter.

Then searches can be sent to specific areas to obtain the location of portable remote units in that geographic area.

The location of any mobile location report unit in a geographic area that is closest to the user will be disclosed to the user. fifteen

[0011] There are many other uses for this type of service to be lucrative for a service provider.

A wireless subscriber may choose to participate in the program and system users may be charged a fee each time the location of another PRU within a requested geographical limit is provided to the user.

Also, users in possession of portable remote units may be charged each time they use Tracking Mode 20 in their PRU.

To improve subscriber enrollment in the program, subscribers can also receive benefits whenever their location is provided to a distressed individual.

Subscribers who do not require their disclosed locations at any time may block such information on the network. 25

In situations where a PRU user is being tracked by another, the network will only reveal the location of the tracking unit only after both units have traveled a certain distance over a pre-specified period of time with the tracking unit while maintaining proximity to the source during that period.

Such distances and elapsed times could be established as an industry standard for clearly defining tracking. 30

[0012] From the foregoing there is clearly a need for a system whereby a remote unit should be able to request the location of other remote units within a specific geographic area.

The components of this type of system are described hereinafter.

 35

Objects of the invention

[0013] It is an object of the present invention to provide a mobile telecommunication system, method and technique that could facilitate the secure provision of location information belonging to one or more mobile communication objectives that are tracking another. 40

[0014] It is an objective of this invention to provide a mobile telecommunication system whereby a communication source residing in a geographical location can probe the location of communication objectives that are present in another geographical area.

 Four. Five

[0015] It is an objective of this invention to provide a technique for reporting the location of communication units within a pre-specified limit.

[0016] It is an objective of the present invention to provide adequate technology that would facilitate the disclosure of location information of communication units that are present in a wider geographic area than normal.

[0017] It is an objective of this invention to provide a remote unit that could provide location information and geographic boundary information where a search could be initiated by the presence of one or more location report communication objectives. 55

Summary of the Invention

[0018] The aforementioned and other objectives are achieved by a telecommunication system that can provide location information pertaining to other communication objectives that are present within a pre-specified geographical boundary.

[0019] In the system, a communication source may ask for the location of communication objectives within a specified geographical limit. The communication source can also enter a mode to determine if another communication unit is tracking it. 65

Sources and objectives of system communication should be able to obtain their location using

any relevant location determination technique.

This information is transmitted securely through the network based on system and subscriber requirements.

When a communication source requires the location information of communication objectives in a specific geographical area, the source obtains its location and can determine whether the geographical limit of the required objectives is within its radius of consultation. 5

Although the design could also be such that the network handles all queries, a communication source can directly poll the target location information within a specified geographic boundary.

This could happen if the communication objectives are within the source's query radios; avoiding unnecessary overhead of shared network resources.

For more complex and distant queries, the source can simply provide its location and geographic boundary information 10 where the objectives should be interrogated for location disclosure.

The network uses its resources and determines where and how a search for relevant communication objectives should begin.

[0020] Once the search for possible communication objectives within the specified geographical limit is completed, the network provides the communication source with information concerning communication objective (s) closest to the source and in the specified geographical region by the source

Brief description of drawings

 twenty

[0021]

Figure 1 shows a general scheme representing the invention.

Figure 2 shows a diagram of a mobile portable remote unit used by the system.

Figure 3 shows a diagram indicating how a wider than normal geographic area is divided to locate remote units in the area. 25

Figure 4 shows a diagram that is used to determine if a remote unit is within a prescribed geographical boundary.

Figure 5 shows a flow chart illustrating the steps that a communication unit can use to determine if it is being tracked by another unit.

Figure 6 is a flow chart illustrating the steps used by a communication unit to reveal a global location when the unit is within a pre-specified geographic area.

Figure 7 is a flowchart that illustrates how a search for the location of mobile communication units is performed at a wider than normal pre-specified geographical boundary.

Detailed description of the preferred embodiment 35

[0022] An overview of the present system according to the invention is represented in FIG. one.

The system consists of a network or portable remote units (PRU) 501-510 scattered across a wide geographical area.

Mobile users 701-709 are in possession of portable remote units 501-509, respectively. 40

Geographic regions 201-204 are standard geographic areas that may be present, one or more portable mobile users 701-709 as shown in FIG. one.

Mobile user 701 is in geographic region 201 and mobile users 502-506 are in geographic regions 202.

 Four. Five

[0023] Other mobile portable users exist in the system and are dispersed as shown in FIG. 1.

Geographical location 201-204 can simply be defined by its latitude, longitude and radius information or simply by points that define its geographical limit as illustrated in FIG. 3.

The terrestrial network center (TNC) FIG. 1,801 is used to control the actions of the mobile system.

The TNC communicates with ground-based transmitters (GBT) 401-404 and ground-based satellite transmitters 50 301-302 to send information concerning the mobile system through the network.

Other features of the land network center may include determining which transmitters to use to complete a call and how to prevent portable remote units from receiving calls when they are outside the jurisdiction.

Multiple ground control or network centers can be used as needed by the system. 55

Ground-based transmitter stations (GBT) FIG. 1,401-404 are used to send mobile information to and from the portable mobile units of the network.

Interface to a fixed telephone network such as home phone or other communication units such as the personal computer could be achieved through the public telephone switching network (PTSN).

101-102 satellites are used by the system to send information to remote areas and also to provide referenced signals, which ground-based communication units can use to establish their geographic location.

Communication between the satellites and the ground network is achieved through 301-302 ground-based satellite transmitters.

 65

[0024] A general internal circuit of a portable remote unit or PRU, FIG 1,501-510 is shown in FIG. 2.

The portable remote unit consists of an antenna 20 and a transceiver circuitry 21.

The transceiver circuitry receives and transmits information from portable remote unit through antenna 20.

Upon receipt, this information is processed and the intelligence portion is extracted and sent to the control unit 22 for further processing.

The transceiver also receives information from the portable remote unit of the control unit 22, processes it, and sends it 5 to the network as needed through the antenna 20.

The control unit 20 controls the action of the PRU.

Relevant information concerning the PRU could be stored in the allocated memory media 26.

Memory media may include random access memory, read-only memory and additional memory for storing PRU data. 10

The input panel 25 is used to take user instructions and the screen 23 is used to present PRU information to a user.

The auditory means 24 is used for the announcement of voice messages.

A PRU may be able to help the network determine its global location or use any location determination technique to resolve and provide its location to the network. fifteen

As a PRU is carried from one location to the other, it can obtain and provide the network with information concerning its current location.

[0025] As stated in one of the objects of the invention and illustrated in FIG. 1, a portable remote unit 501, used by a subscriber 701, in a moving vehicle 601, could be tracked by a clandestine unit 20 510, such a hidden unit in the vehicle 601.

A subscriber - say 704 in region 202 - attempting to keep track of the whereabouts of user 701 in another geographical region may have hidden unit 510 in vehicle 601 to track subscriber 701.

Since most portable remote units are small and compact, they could easily be hidden without the subscriber 701 knowing about such activity. 25

As the vehicle 601 travels from one location to the next, authorized users will be able to receive location information from the PRU 510 whenever they poll it.

As the PRU 510 discloses its location to the authorized party, the party can obtain the location of the subscriber 701 without his authorization.

It is of the utmost importance that a subscriber in possession of unit 501 should be able to determine that they are being tracked by another unit.

In the current invention the subscriber 701 will activate at any point in time the tracking function provided in the PRU 501.

This could be achieved by resorting to the appropriate function through the input panel, FIG. 2.25 of the PRU.

In tracking mode, a tracked PRU, FIG. 1,501, can simply alert a user in possession of the tracked 35 PRU with the location information of any tracking device -PRU 510 -which has resided within a pre-specified radius of the tracked PRU, with both units having traveled a minimum distance .

Parameters such as elapsed time, minimum distance traveled and tracking radios could be established as an industry standard. The tracked PRU could use the tracking function or a request could simply be sent to the nearest ground control station so that the tracked PRU operation is performed.

In tracking mode the geographical location of the tracked unit, FIG. 1, 501, is used to determine the geographical boundary where a search for possible tracking units 510 could be initiated.

For a period of time and at predetermined time intervals, a search of geographic location 201 is sent where the tracked unit 501 resides for all location reporting units within that geographical limit to disclose its location.

The geographical limit required to establish tracking could be established as an industry standard.

For example, it could be agreed that one unit could be considered to track another if it remains within a 5-meter radius of the unit tracked over a stretch of more than 1 mile. fifty

As the tracked unit 501 is moving, that unit or an appropriate network unit can search for the location of other communication units within the tracing limit of the tracked unit to reveal its location.

Only communication units within that geographical limit would reveal their location.

Synchronization information could also be included in the information disclosed to help eliminate errors that may occur when a tracked unit, FIG. 1, 501, is in a vehicle 601 that is moving at high speed.

This exercise could be done at fixed time intervals and over a predetermined period of time.

In the first time interval, a list of all the PRUs that responded within the specified geographical limit defined for the tracking could be maintained. 60

At subsequent time intervals, PRUs that were listed in the first tracking interval and that did not respond at subsequent intervals could be deleted as possible tracking units.

At the end of the tracking period, if there is any unit on the tracking list and the minimum tracking distance was covered, it is considered that such communication units are tracking another and the requested party is informed.

The minimum travel distance must be maintained to eliminate the risk of identifying communication units 65 that reside within a fixed geographical limit over the tracking period as possible tracking units.

Also, a maximum time limit must be set for the tracking exercise so that if the minimum distance is not traveled within that period of time the tracking process is aborted.

If such a time is not maintained a PRU could be in tracking mode indefinitely.

The steps for this process are shown in FIG. 5.

 5

[0026] According to FIG. 5, once the search mode is used in a search unit, the tracking is started, FIG. 5, 1.

Note that the search unit could be any relevant mobile communication unit trying to identify possible mobile communication units that are tracking another.

The search unit then repeatedly operates over predefined time intervals 2 until the end of the 10 tracking period 9, 13.

In each tracking interval 2, the location of the tracked unit is obtained 3.

Possible tracking units within a specified geographic boundary of the tracked unit are searched to reveal their location 4.

For the first tracking interval 5, all tracking units that provided their location in that interval are stored in a list 7. At subsequent tracking intervals, a tracking unit that responded in the first tracking interval and did not respond in a subsequent tracking interval 6 is eliminated as a possible tracking unit.

If the scan list is empty at any scan interval 8, the scan process is aborted 9.

A test 10 is then carried out to verify that the tracking units in the list traveled the minimum predefined distance 20.

If it is determined that the tracking units traveled the minimum distance 10, they are reported to the network 11 as tracking units.

If it is determined that the tracking units have not yet traveled the minimum distance 10, a check is made to establish whether the maximum tracking time has elapsed 12. 25

If there is no time left to set the trace 12, the process is aborted, 13, otherwise it is repeated 2.

A maximum time must be set for the tracking process to ensure that a PRU is not in tracking mode indefinitely.

[0027] As previously indicated, a PRU can resort to this method directly to determine if another 30 units residing in its immediate geographic area have been tracking it.

This would help reduce network overload and, at the end of the tracking period, a status signal can simply be sent to the network.

In circumstances where a tracked PRU cannot perform this operation, a ground control unit can be used to carry out the tracing operation for the PRU and report any findings to the PRU. 35

Maintaining a list of all tracking units in the first tracking interval is effective as it reduces storage space and processing time.

It is also possible to maintain a list of all units that are within a predefined geographical boundary of the unit tracked through the entire tracking process.

At the end of the process, the list could be used to determine which units reported their location over a prespecified distance traveled by the tracked unit.

[0028] For a unit to report a global location within a specified geographical limit, the unit must be able to obtain information from the geographical limit and also determine if its location is within the prescribed limit. Four. Five

There are several techniques well known in the art that a remote unit can employ to resolve its geographic location or help the network resolve its location.

Once the PRU obtains its location by any technique, that information is used to perform the functions according to the invention.

In addition to determining if a remote unit is being tracked, there are other uses for a remote unit 50 to reveal its location in a particular geographic location.

For example, an anguished subscriber at a specific global location may simply want to know if there are mobile users in the immediate geographic area.

In addition, a subscriber may want to know if there is any individual in their home, office or a specified geographic location. 55

By specifying the required location and more information such as radio information, the network can provide a portable remote unit with the location of portable remote targets that are closest to the PRU and in the geographic area specified by the PRU.

For a simple search where the geographic region does not exceed a prespecified limit, a search can simply be sent to the required region so that all units in the region reveal their location. 60

As it would be inefficient to search for portable remote units in wider geographical boundaries to reveal their location, searches in those areas could be managed differently by the network.

In this situation, the network can simply divide the wider area into subregions and ask recursively for the location of PRUs, starting in subregions that are close to the origin before extending to geographic regions that are farther away. 65

To reveal a global location within a prescribed geographical boundary, a PRU in the geographic location

picking up the application must determine if it is within that limit before providing its location to the network.

FIG. 3 shows a geographic location with M1-MN mobile units.

This location is divided into cells (C1-CN) or grids (G1-GN) where N is the total number of cells or grids, also known as region.

Each region could be defined by its latitude, longitude and radius information or by different points that define the 5 grid.

Looking FIG. 3, cell C1 is defined by radius R and its latitude and longitude information is that of the mobile user M1 (Xo, Yo).

G1 grid is defined by four points P1, P2, P3 and P4.

Posterior cells and grids are defined in this way as shown in FIG. 3. 10

FIG. 3 represents a wide geographical area.

Stations and ground control centers, not shown, may also be available in that area.

Such an illustration can also be seen in a general sense in FIG. one.

[0029] As shown in FIG. 3, an anguished mobile user M1 may need to find where there could be another party in that geographical region.

The user could initiate a search from his PRU of the closest available PRUs that could be found in that geographical jurisdiction.

Looking FIG. 3, the mobile user M1 will provide its location, latitude and longitude (Xo, Yo) to the service area of the nearest available land station C1 or grid G1. twenty

As stated earlier, appropriate ground technology will be dispersed in that region to serve the PRUs in that area as shown in FIG 1.

Once a ground station picks up this signal, it sends a search of all location reporting devices at the specified limit that surrounds the mobile unit M1, FIG. 3 to reveal its location.

Such boundary information could simply be specified by the latitude and longitude of unit M1 and information of appropriate radii.

For the first request, such radius information would be the distance R as shown in FIG 3.

A PRU within that area will pick up the signal and determine if it is within the specified radios.

Also, if the ground station specifies grid information for the first cell, G1, a PRU will have to determine if it is within the limit of the GI, P1, P2, P3 and P4 grid. 30

According to FIG. 3, when a ground station sends a search for the location of PRUs in cell C1 or grid G1 only the mobile unit M1 can respond.

Since M1 is the PRU that initiated the search, the ground control station would make the determination and obtain the radius or grid information from the following region for a possible search.

The geographic boundary information of cell C2 or G2 grid will be provided for the next search. 35

Subsequent searches will include the increase in radius information for C1-CN or G1-GN grid limit information until a PRU within that geographic limit responds or system limitations are found.

A possible limitation may be the size of a geographic boundary to search for remote unit locations.

According to FIG. 3, the radius of each cell is from the origin of the mobile unit M1, (Xo, Yo). 40

The radii of posterior cells is a factor of the radius of the first cell, C1.

The grid is normally the narrowest rectangular limit defined by the cell.

As the grid or cells become larger, exclusion zones, as described hereafter, can also be specified if it is necessary that PRUs in certain areas should not reveal their location. Four. Five

Another possibility could be not to increase the following geographical area in a subsequent search but to divide the entire geographical boundary into small regions of approximately the same size.

You could then search in each region, starting in areas that are close to the origin.

This could be done until a PRU in a region reveals its location.

Whereas the mobile unit M1 is initiating a search for possible portable remote units in its immediate area, a relevant ground control station will send three searches.

The first search will cover cell C1 or grid G1.

Since no unit is available in the area, a second search will be sent to cover cell C2 or G2 grid.

Examining FIG. 3, the following PRUs exist only in cell C3 or G3 grid. 55

Once a search is sent to cell C3, PRU, M2 and M3 will respond.

If the G4 grid is specified PRU M2, M3, M4 and M5 will respond.

The ground control station will then select the unit closest to PRU MI, which is M2, in this case.

The location of PRU M2 will then be sent to PRU M1. 60

M1 can also choose to request the number of PRUs in their area and the ground control station will respond again, based on system requirements.

Using the system, a user in possession of a PRU can verify the existence of other PRUs in another geographical location.

A user can select a geographic area of a map presented by the PRU. 65

In FIG. 1, a mobile user 709 at location 204 may use this system to request the location of

mobile units in another geographical region such as 202 or 203.

This could be for example, check to see if there are PRUs in the office or at home or any location of interest.

The system would simply return the appropriate information such as number of responding PRUs, location of PRUs and relevant information requested. 5

In such a system, subscribers can choose to participate to have their location revealed when a search is initiated.

Subscribers can also choose to block or activate this feature at any time on the network.

A subscriber to the service may be charged a fee each time the system is used.

A possible technique used to implement the above is shown in FIG. 7. 10

According to FIG. 7, the geographic information of the area where a search for possible remote targets sought is first obtained.

This information could be provided by a PRU to the network.

This information can simply be the latitude and longitude of the area where the search would be performed and other pertinent information to help the network with the search. fifteen

A PRU can display a map where a user can select a specific geographic area.

From this information the following geographical region where a possible search for PRUs is estimated 2.

This could be the longitude, latitude and radius information of the searched area.

Also, the rectangular grid that surrounds the cell that has that radius information could also be calculated and used. twenty

Once information is obtained, a search is sent to that geographic region for remote units in the region to reveal its location 3.

If remote units are identified in the tracked area 4, that information is sent to network 5 and process 7 is aborted.

If no remote unit is identified in area 4, a check is made to establish if there are any 25 cells or grid remaining higher in the chain to be searched 6.

If there are no regions for a possible search, the process is aborted, otherwise, the process is repeated until all the cells or geographic grids have searched for the existence of portable remote units.

Whenever a portable remote unit receives a signal to reveal its location within a specified geographical limit, the PRU obtains its location and attempts to determine if it is within that limit. As mentioned before, the PRU can employ any relevant location determination technique well known in the art to obtain its geographic location.

If the limit information specified by the network contains a set of well-defined points - latitude and longitude for that region - defining the geographic region, the PRU will simply establish whether its location is within the geographical limit and will provide its location to the network based to that. 35

Points can simply define the minimum and maximum latitude and longitude values within which a PRU should respond.

Such a procedure would be stored in the memory media, FIG. 2.26 of the PRU and invoked by the control unit FIG. 2.22 of the PRU as needed.

If the network simply provides the origin - latitude and longitude - and radius information of the region where a search is to be performed, the PRU will use these values to establish whether it is within the area defined by the network as shown in FIG 4 .

[0030] FIG. 4 shows four moving objects, Object0, Object1, Object2 and Object3.

Considering that Object0 is the source and needs to know if any portable remote unit is available in the geographical region of radio R.

The location of Object0 is the origin of the region and the radio information provided by the network for this region is R.

All objects within that radius must respond upon receiving the signal requesting its location on the specified radios. fifty

Looking at FIG. 4, only Object3 and Object2 exist in the specified region and would respond to the search.

If all mobile objects are served by the same station on the ground, they will all receive the location disclosure signal if they are in the region.

To establish whether they are within the specified region, each mobile object will obtain its location and calculate its tangential information of the specified geographical origin (Xo, I) defined by the source, Object0. 55

The tangent of an angle is normally the opposite / hypotenuse.

Looking at FIG 4, the tangent is between the origin of Object0 and Object1, and that angle is .

As Object3 is on the same line as Object1 the tangent between the origin of Object0 and Object3 is also 

The tangent between the origin of Object0 and Object2 is 

Standard trigonometric equations dictate that the tangent of an angle is the opposite / hypotenuse. 60

According to FIG. 4, Tan  = (y1-yO) / (x1- xo) for Object1 and (y3-yO) / (x3- xo) for Object3, for Object2 Tan  = (y2-yO) / (x2- xo) .

Once the inclination or tangent of the object to the origin is calculated, the distance from the object to the origin could easily be calculated using the sine formula -Seno  = opposite / hypotenuse where the opposite is (y1 - me), (y3 -yo) for Object1 and Object3 respectively. 65

The hypotenuse is the distance from the moving object to the origin; Ro1 and Ro3 for Object1 and Object3 respectively.

For Object2, the distance from the origin Ro2 = (y2- yo) / Sinus 

Once the distance from the origin (XoYo) is calculated for each mobile object, an assessment could easily be made as to whether the mobile object is within the specified limit and the location of the mobile object could be provided to the network based on that . 5

In addition, the network may choose to provide a region or regions of exclusion to portable mobile remote units or PRUs.

A PRU in that exclusion region will not reveal its location to the network even if it is within the specified geographical limit of the network.

These exclusion zones can be specified simply as grid points at any site in the tracked region or as an aft direction of origin.

An aft origin address contains information that will tell PRUs in the region not to reveal their location if they are east, west, north or south of the origin.

Considering FIG. 3 as another example, if a request is received in that region for the location of mobile units in G4 or C4 and the origin is the location of M1, with the exclusion zone specified as this, all 15 mobile units in G4 or C4 They will receive the request to reveal the location in that area.

After detecting the exclusion zone information in the signal only the mobile units west of M1 will reveal its location.

Again, such exclusion zone information may simply specify subregion (s), where PRUs should not disclose their location. twenty

[0031] FIG. 6 shows the steps used by a remote unit to reveal its location if it is within the geographical limit specified by the network.

The unit first obtains information from the geographical limit specified by network 1.

This information may consist of latitude and longitude information that defines the origin of regions and radius information.

[0032] The following unit obtains its location 2.

This could be done in association with the network or using any remote unit location determination technique such as GPS. 30

The next step is to determine if the unit is within the limit prescribed by network 3.

Such a technique has already been described in the invention.

Other checks are made to ensure that the remote unit is not in the zone of location reporting exclusion defined by network 4.

The location of the remote unit is provided to the network 7 once it is established in the remote unit that the subscriber 6 authorized such action.

[0033] It could be mandatory for all PRUs to reveal their location once they receive a request to establish the tracking.

A PRU may not respond to any tracking by establishing routines if it is in a fixed location. 40

Tracking is only possible when the tracking unit and the tracking unit are in motion.

If a network request is about to establish if a PRU is within a geographic location, the PRU response could be based solely on the subscriber's requirements - whether such action is authorized or not.

A PRU may choose to instruct the network to send certain information to mobile units in a specific geographic region. Four. Five

That information would then be attached to the geographic boundary information and would be issued in the specified geographical region.

The target PRUs would determine if they are within the specified limit before alerting a subscriber as to the content of the message.

In circumstances where a subscriber in possession of the PRU is on the move and a request is received for the location of the PRU if it is within a specified region, the PRU can provide this information and also provide the network with additional information such as its speed .

This could help a party seeking help to establish if they would be able to reach another subscriber in the region where help was sought.

Also, a party requesting the location of remote units in a geographical limit can also send information at maximum speed.

If a PRU is in the region and establishes that its speed is above what is specified, no response is sent to the network.

A PRU can calculate its speed using the equation, speed = distance / time.

In time intervals T1 and T 2, a PRU can obtain its location, Y1 and Y2 and calculate the distance between these 60 two points, as previously disclosed.

The speed is given by (distance between Y2 and Y1.) / (Time in Y2- Time in Y1.

Such information could then be provided to the network.

In situations where a PRU cannot perform any of the tasks described here, the network can obtain its location information and the required functions performed on the network and forwarded to the communication objective 65 appropriate to its term.

Claims (4)

1. Method for providing the location of a portable mobile remote unit, PRU (501,510), associated with a telecommunications network comprising: I) obtain geographic boundary information in the network within which the location of the PRU should be disclosed; Ii) request the location of PRUs within said geographical limit, Iii) obtain the location of a PRU within the network and determine if the PRU is within said geographical boundary; Iv) send the location of the PRU to the network after the determination that the PRU is within said geographical limit 10. 2. A method according to claim 1 for determining whether a PRU is within a prescribed geographical limit comprising: obtain radio information of said geographic boundary of the network; fifteen obtain geographic information describing the origin of said geographical limit; calculate the angle of inclination of said PRU to said geographical boundary origin; calculate from said angle of inclination the distance between the PRU and said geographical boundary origin. 3. Method according to claim 1 for determining whether a PRU is within a specified geographical limit comprising: obtain from the geographic information of the network that describes said geographical limit; estimate in the PRU if the current location of the PRU is within that geographical limit obtained in the network.  25 4. Method according to claim 1 used to further limit the provision of the location of the PRU to the network comprising: obtain information on the network from the exclusion region within which the PRU should not provide its location to the network; determining that the PRU is not in said exclusion region before providing the location of the PRU 30 to the network.