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Personal locator system    
United States Patent5485163   
Link to this pagehttp://www.wikipatents.com/5485163.html
Inventor(s)Singer; Martin H. (Northbrook, IL); Tell; Daniel (Deerfield, IL); Kobrinetz; Anthony (Hoffman Estates, IL)
AbstractA system and method for locating a portable locator device in a communications network. The portable locator unit (PLU) (4) is activated either by an external signal (62) generated in response to remote activation source, such as a subscriber (6, 8) or PLU detector (106, 108), or by an internal activation signal triggered e.g. by the wearer. Once activated, the PLU (4) transmits a location signal (66). This location signal (66) is received by one or more network service nodes (20, 22, 24) which forward the information along with identifying service node information to a network location processor (26, 28). After having determined the location of the PLU (4) from the received information, the network location processor (26, 28) forwards this information to a designated source, such as the requesting subscriber or other authorized user (6, 8).
   














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Drawing from US Patent 5485163
Personal locator system - US Patent 5485163 Drawing
Personal locator system
Inventor     Singer; Martin H. (Northbrook, IL); Tell; Daniel (Deerfield, IL); Kobrinetz; Anthony (Hoffman Estates, IL)
Owner/Assignee     Motorola, Inc. (Schaumburg, IL)
Patent assignment
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Publication Date     January 16, 1996
Application Number     08/220,342
PAIR File History     Application Data   Transaction History
Image File Wrapper   Patent Term   Fees
Litigation
Filing Date     March 30, 1994
US Classification    
Int'l Classification    
Examiner     Blum; Theodore M.
Assistant Examiner    
Attorney/Law Firm     Toler; Jeffrey G. Buford; Kevin A.
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Patent Tags     personal locator
   
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 Technical Review Submit all comments and votes
 Claims Submit all comments and votes
 


What is claimed is:

1. A method of locating a portable locator unit (PLU) in a communications system comprising the steps of:

a) accessing the communications system and requesting location of the PLU to be sent to a receiving device;

b) sending a signal from the communications system to the PLU;

c) sending a response, including a PLU identifier, from the PLU;

d) receiving the response at a first node of the communications system. said first node having a node identifier;

e) providing location information within the communications system indicative of the location of the PLU based on analysis of the node identifier;

f) determining a desired format for the location information based on the PLU identifier; and

g) providing the location information of the PLU in the desired format to the receiving device.

2. The method of claim 1, wherein the step of sending a signal further comprises sending the signal from a second node of the communications system.

3. The method of claim 2, wherein the step of sending a signal further comprises sending an activation message over a control channel to the PLU and said response is sent over the control channel.

4. The method of claim 1, wherein the step of sending a response further comprises measuring a signal quality level of control channel transmissions from plural nodes of the communications system including the first node, and sending the response to the first node when its signal quality level exceeds the signal quality level of the control channel transmissions of the other of the plural nodes.

5. The method of claim 4, wherein the step of sending a response further comprises sending information about the measured control channel transmissions of the first node and at least two of the other plural nodes.

6. The method of claim 5, wherein the step of providing location information further comprises using the signal quality levels of the measured control channel transmissions to locate the PLU.

7. The method of claim 1, wherein the step of providing the location information further comprises dialing a number of the receiving device and forwarding the location information to the receiving device.

8. The method of claim 7, wherein the location information is forwarded to the receiving device in at least one of a audio and a visual communication format.

9. The method of claim 1, wherein the node identifier is associated with the location of the first node.

10. A method of locating a portable locator unit (PLU) in a communications system comprising the steps of:

a) monitoring by the PLU for a remote activation signal;

b) receiving the remote activation signal by the PLU;

c) transmitting a location signal including a PLU identification by the PLU;

d) receiving the location signal at a first node of the communications system, and forwarding the PLU identification and a first node identification to a location processor in the communication system;

e) determining PLU location information by the location processor from the PLU identification and node identification;

f) storing the PLU location information in a location memory; and

g) providing the location information to an authorized recipient,

11. The method of claim 10, wherein the first node is a cellular base station and step a) further comprises monitoring a control channel of a cellular base station for a remote activation signal comprising a PLU identifying number and a PLU extended protocol activation command.

12. The method of claim 10, further comprising accessing the communications system and requesting location of the PLU to be sent to the authorized recipient a designated receiving device, sending a remote activation signal from the communications system to the PLU and transmitting the location information to the authorized recipient at the designated receiving device.

13. The method of claim 10, wherein steps a) and b) comprise measuring signals from a monitor unit for a remote activation signal consisting of a received signal below a predetermined signal level.

14. The method of claim 10, further comprising monitoring by the PLU for a signal from a detector, transmitting a response by the PLU upon receiving the signal from the detector, and generating an activation signal for transmission to the PLU.

15. The method of claim 14, further comprising disabling monitoring by a remote activation signal in response to a received inhibit signal.

16. The method of claim 10, further comprising:

determining by the PLU from a signal from a second node that the PLU has moved from a coverage area of the first node into a coverage area of the second node;

sending a further location signal in response to the determined move;

receiving the further location signal at the second node and forwarding the PLU identification and a second node identification to the location processor;

determining a further PLU location information by the location processor from the PLU identification and second node identification;

storing the further PLU location information in the location memory.

17. The method of claim 16, wherein the step of determining a further PLU location is performed at a second location processor coupled to the second node.

18. A method of locating an object bearing a portable locator unit (PLU) in a communications system comprising the steps of:

a) monitoring by the PLU for an activation signal;

b) receiving the activation signal by the PLU;

c) transmitting a location signal including a PLU identification by the PLU;

d) receiving the location signal at a node of the communication system, and forwarding the PLU identification and a node identification to a location processor coupled to the node;

e) determining PLU location information at the location processor from the PLU identification and node identification;

f) storing the PLU location information in a location memory; and

g) providing the PLU location information about the PLU's location to an authorized subscriber in communication with the communications system.

19. The method of claim 18, further comprising the step of generating the activation signal by the PLU in response to the removal of the PLU from the object.

20. The method of claim 18, wherein the object is a person, and further comprising the step of generating the activation signal by the PLU in response to a predetermined act by the person.

21. A method of locating a portable device in a communications network comprising the steps of:

a) sending a node identification signal from each of a plural nodes of the communications network;

b) receiving at least one node identification signal at the device and determining a node coverage area corresponding to a first of the plural nodes in which the portable device is located from the received at least one node identification signal;

c) determining by the device, from a second node identification signal, when the device moves into a second node coverage area, and sending a registration signal, including a device identification in response to the determined change in coverage area;

d) receiving the registration signal at the second node, and forwarding the device identification and a node identification to a network location processor; and

e) determining a current location of the device from the device identification and node identification of the second node; and

f) storing the location information indicative of the determined current location in a location register.

22. The method of claim 21, wherein step e) further comprises forwarding the location information to an authorized user.

23. The method of claim 21, further comprising:

g) determining the location of an authorized user requesting the location information, determining the relative position of the current location of the portable device from the location of the authorized user, and providing the determined relative position to the authorized user.

24. The method of claim 21, wherein the step of sending the registration signal further comprises:

sending a return echo of the second node identification following a predetermined delay from receipt of the second node identification; and

receiving the registration signal further comprising measuring the return echo signal to determine distance information of the device from an antenna of the second node receiving the registration signal and forwarding the determined distance information along with the device identification and the node identification of the second node.

25. The method of claim 24, wherein the antenna is a sector antenna having a known coverage region, and the step of receiving the registration signal further comprises forwarding information indicative of the known coverage region of the sector antenna.

26. The method of claim 21, further comprising the steps of:

sending a channel assignment signal to the portable device;

receiving the channel assignment signal and transmitting a periodic location signal by the device on the assigned channel;

measuring a predetermined characteristic of the channel assignment signal by the second node and by a plurality of neighboring nodes;

forwarding the characteristic measurement and node identification from each node along with the device identification to a location processor; and

determining the location of the portable device by determining the location of each node from the node identification of each node and comparing the characteristic measurement measured at each node.

27. The method of claim 26, further comprising the step of:

determining the location of an authorized user requesting the location information, determining the relative position of the current location of the portable device from the location of the authorized user, and providing the determined relative position to the authorized user.

28. A communications system for locating a portable locator unit (PLU) and informing a subscriber of the location, comprising:

means for accessing the communications system and requesting location of the PLU to be sent to a receiving device;

means for sending a signal from the communications system to the PLU;

means for sending a response, including a PLU identifier, from the PLU;

means for receiving the response at a first node of the communications system, said first node having a node identifier;

means for providing location information within the communication system indicative of the location of the PLU based on analysis of the node identifier;

means for determining a desired format for the location information based on the PLU identifier; and

means for providing the location information of the PLU in the desired format to the receiving device.

29. The system of claim 28, wherein the means for sending a signal is operable for sending an activation signal from a second node of the communications system.

30. The system of claim 29, wherein the means for sending a signal is further operable for sending a paging signal to the PLU including an activation command.

31. The system of claim 28, wherein the means for sending a signal is operable for sending a registration signal from the first node.

32. The system of claim 28, wherein the means of sending a response is operable for measuring signal strength of control channel transmissions from plural nodes of the communications system including the first node, and sending the response to the first node when its measured signal strength is greater than the measured signal strength of the other of the plural nodes.

33. The system of claim 32, wherein the means for sending a response is further operable for sending information about the measured control channel transmissions of the first node and at least two of the other plural nodes.

34. The system of claim 32, wherein the means for sending a response is further operable for sending the response to the first node after a predetermined delay, and for sending second and third responses to second and third node control channel transmissions after a same predetermined delay.

35. The system of claim 34, wherein the means for receiving is further operable for receiving the second and third responses and the means for determining the location is further operable for using the response and second and third responses to locate the PLU.

36. The system of claim 28, wherein the means for providing the location is further operable for dialing a number of the receiving device and forwarding the location information to the receiving device.

37. A communications system for locating a person bearing a locator unit via a communications channel using a wireless link to the locator unit, and for forwarding the location to a subscriber unit, comprising:

a home location memory having stored locator unit subscriber information and location information about the locator unit;

a first wireless communication node serving a first coverage area in which the locator unit is located and operable for receiving a location signal from the locator unit;

a first node location determining processor coupled to the first node and operable for determining the location of the locator unit from the location signal received at the first node, and transmitting further location information about the locator unit; and

a subscriber call processor coupled to the first node location determining processor operable for receiving the transmitted further location information, and coupled to the home location memory operable for updating location information based on the further location information and generating a subscribed call, based on the stored locator unit subscriber information, containing the further location information.

38. A communications system for locating a person bearing a locator unit via a communications channel using a wireless link to the locator unit, and for forwarding the location to a subscriber unit, comprising:

a first wireless communication node serving a first coverage area in which the locator unit is located and operable for receiving a location signal from the locator unit;

a home location memory having stored locator unit subscriber information and location information about the locator unit;

a subscriber request processor coupled to the home location memory and operable for processing a subscriber location request about the location of the locator unit and transmitting a further location request including the locator unit identifier information to the first wireless communication node;

a first node location request processor coupled to the first node and operable for receiving the further location request and controlling the first node to send a location activation signal to and receive the location signal from the locator unit;

a first node location determining processor coupled to the first node and operable for determining the location of the locator unit from the location signal received at the first node, and transmitting further location information about the locator unit; and

a subscriber call processor coupled to the first node location determining processor operable for receiving the transmitted further location information, and coupled to the home location memory operable for updating the location information, based on the further location information, and generating a subscriber call, based on the stored locator unit subscriber information, containing the further location information.
 Description Submit all comments and votes
 


FIELD OF THE INVENTION

This invention relates to a system for locating persons or objects, and in particular a wireless communication system for use in locating and tracking persons and/or objects.

BACKGROUND OF THE INVENTION

Today's news numbs us with accounts of kidnapping and theft. Even the most hardened cynics are haunted by the stories of child abductions: a stranger dragging a child from her home, adolescents taking a screaming toddler from a shopping mall, infants kidnapped from a hospital. Constant vigilance, and fear, have become all to common place for parent and child alike.

Those solutions that have been offered in the past are of limited effectiveness, or as a practical matter unavailable to the average person. Child monitoring devices, such as described in U.S. Pat. No. 4,899,135, have a limited range, and once a child is beyond that range provides no means for relocating the child. Emergency locator systems, such as shown in U.S. Pat. No. 5,021,794, provide a means for homing in on a child from a greater range, but also require the additional assistance of mobile homing units and remain ineffective beyond a still limited broadcasting range of the homing beacon.

While there are technologies offering better location methods, these remain mostly out of reach of the average person due to the cost prohibitive nature of the solution. Thus, while RF tags installed on vehicles permit the location of stolen automobiles, the transmitters for such tags require high power sources (car batteries), are relatively expensive (currently over five hundred dollars), and require the intervention of local police with additional hardware and software (at more expense) for tracking the car. Emergency systems, such as that described in U.S. Pat. No. 5,218,367, represent similarly expensive solutions, relying upon an on board emergency activation circuitry and a high power source for the continuous multicell control signal scan and the response transmissions thereto. Likewise, any system incorporating a GPS (Global Positioning System) receiver will, although providing accurate location information, add undesirable bulk and several hundred dollars expense to the locator device.

Any solution to this need for inexpensive locator devices should also be balanced against the right to privacy in our own personal affairs. Safeguards must exist against unwanted third party (listening) in on others' locations. Thus, while any effective solution will provide an inexpensive locating system, it should also include subsystems to ensure that only those persons authorized to follow the movements of a locator device will in fact have access to the location information.

Finally, it is also desirable that any such solution provide the location information without requiring the intervention of our already overtaxed emergency services, except where necessary.

SUMMARY OF THE INVENTION

These needs and others are substantially met by the system and method disclosed herein for locating a portable locator device in a communications network. The portable locator unit (PLU) is activated either by an external signal generated at a remote activation source, such as a subscriber or PLU detector, or by an internal activation signal triggered e.g. by the wearer. Once activated, the PLU transmits a location signal. This location signal is received by one or more network service nodes which forward the information along with identifying service node information to a network location processor. After having determined the location of the PLU from the received information, the network location processor forwards this information to a designated source, such as the requesting subscriber or other authorized user.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a communications network in accordance with the present invention.

FIG. 2 illustrates a flowchart of steps for locating a PLU using a first embodiment of the present invention.

FIG. 3 is a flowchart of further steps that may be used in determining and communicating the location of the PLU in accordance with another embodiment of the present invention.

FIG. 4 is a flowchart of yet another embodiment for activating a PLU in accordance with the present invention.

DESCRIPTION OF A PREFERRED EMBODIMENT

The present invention provides a unique solution to the problems discussed above by using a low power and inexpensive portable locator unit (PLU) in conjunction with a communications system having wireless service nodes to allow a subscriber to locate the PLU. FIG. 1 illustrates one such communications network. In this case the portable locator unit (PLU) 4 is attached to a lost or abducted child, and has the form of a tag, an ornamental bracelet, or the like. While the PLU has been illustrated taking this specific form, with appropriate miniaturization it could be incorporated in almost any object, such as a belt, watch, earring, etc. The PLU includes a low power source, a transceiver, a memory for storing instructions and other information (such as the PLU identification) necessary for the operation of the unit, and an antenna (not shown). It is preferred, in order to conserve power, that the PLU be in receive only mode until activated for location purposes.

Following activation of PLU 4, the location of PLU 4 is determined using one or more service nodes of a communications network. These nodes are illustrated in FIG. 1 as base transceiving stations (BTS) 20, 22, and 24 of a communications network including a cellular telephony infrastructure. The network is not limited to a cellular system, and in some regions may not even include any cellular service nodes. Thus, the service nodes may be part of such differing systems as a trunked radio, satellite, or personal communicator service (PCS) system, and it is expected that an integrated network will include all these and more. The only requirement is that the network include service nodes capable of wireless communication with the PLU.

In networks having sufficiently small nodes, such as microcellular networks, the location of PLU 4 may be determined with sufficient precision solely based upon its location within the coverage area 16 of one such node 20. In larger cells having sector antennas, the approximate location of PLU 4 may be determined based on the coverage area 18 of the receiving sector transceiver. However, in cells larger than microcells, and where more than an approximate location is desired, one or more additional steps in determining the location of PLU 4 may be used, as discussed below in connection with FIG. 3.

Where BTS 20 is a microcellular node, the location information forwarded from BTS 20 to base station controller (BSC) 30 may be as simple as a signal containing an identifier like the mobile ID number (MIN) of PLU 4 and a node ID number (NIN) for BTS 20. BSC 30 may alternatively be a cellular or wireless application processor (C/WAP) connecting directly to the Public Switched Telephone Network (PSTN) 32 via a telephone switch (not shown). BSC 30 is connected to mobile service switching center (MSC) 28. Attached to MSC 28 is a location register. The location register handles both visiting as well as home location functions, depending on whether a PLU is registered with its home location in MSC 28 or elsewhere.

In the illustrated embodiment a visiting location register (VLR) 26 is attached to MSC 28. The home location register (HLR) 36 for PLU 4 can be directly coupled to PSTN 32 or coupled via one or more MSCs. While it is not essential that a VLR 26 be utilized, it is preferable in view of factors such as the multiple operators likely to be functioning within the communications network. For example, by utilizing information stored within its local VLR 26, one operator can identify the geographic location of BTS 20, or even subregions such as sector coverage area 18, based on the identifying information forwarded from BTS 20. This geographic information, as well as the MIN of PLU 4 and the time of receipt, may then be forwarded to the HLR 36 via the MSC 28 and PSTN 32. This simplifies the amount of information that would otherwise be required to be retained at each location register throughout the network, and in some instances such information (such as that identifying sector coverage areas) may not as a practical matter be available to a location register of a competing operator or operators of different types of systems.

Finally, each HLR preferably contains subscriber preference information directing how the PLU location information is to be communicated. Such preferences may include the means by which the information is to be communicated, e.g., by data or voice over wireline or wireless (paging or cellular) systems to a specified end system or receiving device (e.g., cellular phone), and the desired forgnat (e.g., geographical location, proximate place names (buildings), relative position and the like).

One skilled in the art will also recognize that significant extra features will be available for PLUs equipped and operating within advanced operator systems such as NAMPS (Narrowband Advanced Mobile Phone Service). By use of extended protocol messages, PLUs can register without interfering with regular mobile registrations. They can also be sent instructions (e.g. to "register" at set intervals or tune to a channel) without the PLU using uplink resources. Further, a mobile tracker (6) can be sent location updates as data signals on the control channel, without the need for being assigned a traffic channel.

Turning now to FIG. 2 one embodiment for implementing the invention in a network including a cellular system is illustrated. The location service is initiated in this embodiment by a request from a subscriber. This request may be initiated by dialing an assigned number for the PLU. When dialing into a PSTN directly from a fixed station such as telephone 8 of FIG. 1, the number for PLU 4 may need to be preceded by an appropriate system access number. When accessing the system from a wireless environment, such as from mobile unit 6 of FIG. 1, appropriate system protocols may be used, such as adding a suffix to the PLU number identifying the call as a location request for a PLU. Once the call has been connected, the subscriber is prompted to enter a PIN assigned for the location services for PLU 4. Upon confirmation of the PIN, the subscriber may be prompted to enter the form of services desired (if not already identified by a protocol), e.g., location, maintenance or the like.

Following a request for the location of PLU 4, service parameters regarding PLU 4 are read from HLR 36 and used for activation of PLU 4. Thus, where PLU 4 is set up to be activated, e.g., by an area wide page command, an activation command is forwarded to the paging system for broadcast from a paging antenna (12) as a page message (signal 10) to PLU 4. On the other hand, where PLU 4 is only set up to transmit and receive over cellular telephony bands, an activation command will be forwarded throughout the participating cellular operating systems of the network to be transmitted from each BTS. In order to conserve system resources, one skilled in the art will appreciate that appropriate algorithms may be employed to search for PLU 4, starting for example either at the cells in proximity to the HLR 36 or proximate some other location designated by the subscriber as the last known location of PLU 4.

Upon receipt of the activation signal, PLU 4 switches from receive only mode to receive and transmit mode. In this mode, PLU 4 monitors the paging or control channels of local BTSs to determine the transmission channels being used by the BTSs. PLU 4 then registers with the strongest BTS, transmitting a location signal (LS) that includes the PLU's MIN. This information is forwarded, along with the node identification number (NIN) of receiving BTS 20, to the VLR 26 via BSC 30. VLR 26 translates the NIN, or other received location identifying information from BTS 20 via a lookup table to determine the approximate geographic location of PLU 4. This location information, along with the time of receipt, is then forwarded to HLR 36 using the MIN address information.

Final