Patent Publication Number: US-2002000930-A1

Title: Location detection system

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
     [0001] This application is a continuation-in-part of U.S. patent application Ser. No. 09/535,932, filed Mar. 24, 2000. 
    
    
     
       FIELD OF THE INVENTION  
       [0002] The present invention relates to communication systems in general, and in particular, to systems for locating mobile objects or people.  
       BACKGROUND OF THE INVENTION  
       [0003] In response to a Federal Communications Commission (FCC) mandate, cellular phone providing services will be required to implement technologies which allow the location of a cellular phone user to be determined when the user dials an emergency number such as 911. This location information will be given to emergency call centers, which can then speak with the user directly, and if necessary, dispatch people to the user&#39;s location in order to render assistance.  
       [0004] At the present time, the location information that can be provided to a cellular service provider is limited to a location and maybe a map of the geographic area of the particular cellular tower that is handling the cellular call. Because the geographic area serviced by such a cellular tower can be quite large, emergency personnel are often limited in their ability to accurately locate the caller in the event that they cannot speak with them directly. Also, cellular systems do not guarantee the delivery of an emergency call if a user initiates the call outside of their home coverage area.  
       [0005] Given this problem, there is a need for a more accurate location determining system that can provide emergency service personnel or others with an accurate indication of a caller&#39;s position.  
       SUMMARY OF THE INVENTION  
       [0006] The present invention is a position sensing system that incorporates global positioning satellites (GPS) and a two-way paging system. Upon local activation by a user or remote activation by a paging service, a two-way paging device interacts with a GPS receiver to transmit position or location information for the user. This information is transmitted by the two-way pager to a location determination service and, in some embodiments, a location server, which provide the location of the position sensing system to a requestor who accesses the location determination service via a computer or telephone or other two-way communication device.  
       [0007] In one embodiment of the invention, the position sensing system, including GPS receiver and two-way pager, is associated with a cellular telephone. The location determination service provides the location of the cellular telephone to a cellular call processor when a user of the cellular telephone makes an emergency call. The cellular call processor uses the location information to select a specific emergency agency to handle the emergency call. In addition, the location determination service can use the location information to request a map showing the location of the cellular telephone from a GIS layer and data service to be forwarded to the selected emergency agency indicating the precise location of the caller.  
       [0008] In accordance with another aspect of the present invention, the position sensing system, including GPS receiver and two-way pager, is incorporated into a cellular phone battery pack. The location of the battery pack can be provided to a requestor without interfering with a cellular phone call made by a user. The battery pack may include a “panic” button that can be activated by a user to cause the two-way pager to interact with the GPS receiver and transmit its position or location information independent of a cellular phone call.  
       [0009] In accordance with yet another embodiment of the invention, the position sensing system, including two-way pager and GPS receiver, can be placed on any object (automobile, shipping container, etc.) or carried by people in order to determine a location of the object or person. The location determination service can be accessed via a telephone or via a computer or other two-way communication device to determine the location of a specific position sensing system.  
       [0010] In accordance with yet another aspect of the present invention, a position sensing system including a GPS receiver and a two-way wireless device can use the location of an object whose position is known as a surrogate for the location of the position sensing system if the position sensing system cannot receive GPS signals. In one embodiment, the location of a paging transceiver is used as a surrogate for the location of the position sensing system, if the position sensing system cannot receive GPS signals. In another embodiment, an object may comprise a Bluetooth™ transceiver whose position is known. The location of a particular transceiver is used as a surrogate for the location of the position sensing system when the GPS receiver cannot receive signals from the GPS satellites. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0011] The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:  
     [0012]FIG. 1 illustrates a conventional position sensing system for cellular telephone users;  
     [0013]FIG. 2 illustrates a position sensing system of the present invention that is integrated with a cellular telephone system;  
     [0014]FIG. 3 illustrates a position sensing system, including an integrated GPS receiver, two-way pager, and battery pack, in accordance with another aspect of the present invention; and  
     [0015]FIG. 4 illustrates a position sensing system according to another embodiment of the present invention that operates as an independent system. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0016]FIG. 1 illustrates a conventional method of determining the approximate position of a cellular caller during an emergency or 911 call. When a user of a cellular telephone  10  makes a telephone call, the radio frequency (RF) signals are transmitted to and received by one or more cellular towers  12 ,  14 . A cellular call processor or router  18  determines which cellular tower  12 ,  14  should handle the call based on strength of the RF signals received from the cellular telephone  10 . Should the position of the cellular telephone  10  change such that the received signal strength fades at one cellular tower and becomes stronger at another, the call processor  18  directs the cellular tower to hand off the call to the cellular tower with the strongest-received signal.  
     [0017] When a user makes a 911 call, the call processor  18  briefly determines which cellular tower  14  is handling the call and, based on an identifier for that tower, requests position information from a location determination service  19 . The information provided by the location determination service  19  does not indicate the location of the caller, but instead provides the geographic location of the cellular tower handling the call. Based on the location of the tower that is handling the call, the cellular call processor  18  determines which of a number of emergency agencies  20 ,  22  should receive the emergency call. The call processor then routes the call to the agency having the closest proximity to the cellular tower that is handling the cellular telephone call. In addition, a map showing the vicinity of the cellular tower may be routed from the location service  19  to the selected emergency agency.  
     [0018] Because the cellular towers  12 ,  14  may have a relatively large geographic area in which they service calls, the particular emergency agency  20 ,  22  to which the call is routed does not have any more specific information concerning the position of the caller other than the location of the cellular tower handling the call. If the emergency agency is not able to speak to the cellular caller (if, for example, they are incapacitated), the emergency agency has little information that can be used to direct field personnel to the caller.  
     [0019] To improve the accuracy by which a cellular telephone can be located, the present invention incorporates the accuracy obtained with a global positioning system (GPS) and the communication ability of a two-way paging system.  
     [0020] As shown in FIG. 2, a cellular telephone  50 , in accordance with one aspect of the present invention, has a position sensing system  52  associated with it. The position sensing system  52  includes a GPS receiver  54  and a two-way pager  56 . When a user makes an emergency call, such as a 911 call, RF signals from the cellular telephone  50  are received by a cellular tower  60  and forwarded to a cellular call processor or router  62 . Before forwarding the call to an appropriate emergency agency  80 ,  82 , the call processor  62  interacts with a location determination service  64  in accordance with the present invention. The location determination service  64  receives an identifier (typically, its assigned phone number or other identifying code) of the cellular telephone  50  making the call from the cellular call processor  62 . Based on the identifier of the calling cellular telephone  50 , the location determination service  64  accesses a database  66  that determines if the cellular phone is equipped with a position sensing system  52 . If the cellular telephone  50  does not have a position sensing system  52 , the location determination service  64  instructs the cellular call processor  62  to handle the call in the conventional fashion by determining the geographic location of the cellular tower  60  handling the call and routing the call to the emergency agency  80 ,  82  having jurisdiction of the area of the handling cellular tower  60 .  
     [0021] If the cellular telephone  50  is equipped with a position sensing system  52 , the location determination service  64  sends a message to a two-way paging service  68  that initiates a page to the two-way pager  56 . The page is received by the two-way pager  56 , and the two-way pager  56  interacts with the GPS receiver  54  to receive position information from one or more overhead GPS satellites  70 ,  72 . In the presently preferred embodiment of the invention, the two-way paging system  68  and two-way pagers  56  are Reflex™ based systems produced by Glenayre Electronics, Inc., under license from Motorola. However, other two-way paging systems, such as Ardis or Mobitex, could be used.  
     [0022] The GPS receiver  54  is preferably based on a network aided, differential GPS system made by Snap Track of San Jose, Calif., and described in U.S. Pat. Nos. 6,016,119; 6,002,363; 5,999,124; 5,945,944; 5,884,214; 5,874,914; 5,841,396; 5,831,574; 5,825,327; 5,812,087; and 5,781,156, which are herein incorporated by reference. These GPS receivers have the ability to quickly determine position information in adverse conditions, such as in buildings, etc., by preloading GPS acquisition information for the position signals being transmitted from the overhead satellites, as will be described in further detail below. However, other GPS receivers could be used if desired.  
     [0023] Depending on the processing power available at the position sensing system  52 , the GPS receiver  54  may calculate its actual location (i.e., latitude/longitude) from the GPS pseudo-range position information received from the GPS satellites and provide the calculated latitude/longitude to the two-way pager  56 . Alternatively, the GPS receiver may simply provide the pseudo-range position information to the two-way pager  56  to transmit. For the purposes of the present specification the terms position and location are used interchangeably as context requires, but the terms “position information” is generally meant to refer to the raw pseudo-range information received from the GPS satellite  70 ,  72 , and “location information” generally refers to an actual location (i.e., a latitude and longitude) that is calculated from the position information.  
     [0024] Once the GPS receiver  54  has received the pseudo-range position information from the GPS satellites  70 ,  72 , the position or location information is provided to the two-way pager  56 , which forwards the position or location information back to the two-way paging system  68  on a reverse paging channel. The paging system  68  returns the position or location information to the location determination service  64 . If location information is received, the location determination service  64  can provide the latitude and longitude received to the cellular call processor  62 . Alternatively, the location determination service  64  can access the database  66  that includes data to convert the latitude and longitude received to a routing code, which is provided to the cellular call processor  62  for routing the call to the appropriate emergency agency  80 ,  82 . The database  66  also stores user profile data and rules for handling the location information received as will be described in further detail below.  
     [0025] If desired, the location determination service  64  may request a map illustrating the precise location of the user from a GIS layer and data service  74 , such as that provided by ETAK of Sunnyvale, Calif. The GIS layer and data service is coupled to the location determination service  64  via a communication link, such as the Internet. The GIS layer and data service  74  generate a map and/or street address from a given set of latitude and longitude coordinates. The location determination service  64  may forward the map and/or street address showing the location of the caller to the selected emergency agency  80 ,  82 .  
     [0026] If the information received from the two-way pager  56  is the pseudo-range information, the location determination system  64  may forward the received position information to a location server  75  that is programmed to produce a precise latitude and longitude from the received pseudo-range information. The calculated latitude and longitude are returned to the location determination service  64  and processing proceeds as described above. If desired, the location determination service  64  may correct the pseudo-range information based on data received from a differential GPS system  77 , as will be described in further detail below.  
     [0027] As will be appreciated, the position sensing system  52  allows the location of a cellular caller to be determined with a far greater accuracy than was available in the prior art. In addition, the present invention can utilize the store and forward capability of the two-way paging system to ensure that a request for the two-way pager  56  to transmit its position or location information is not missed if a user is out of range. Paging systems will typically rebroadcast a page over a predetermined period, such as three days, etc., until a pager has received it. Therefore, a user who was out of range and then comes back in range will receive the page requesting their location.  
     [0028]FIG. 3 illustrates in further detail the position sensing system  52  and illustrates one way in which the position sensing system  52  may be integrated with a cellular telephone. In this embodiment of the invention, the position sensing system  52  comprises an integrated cellular telephone battery pack, including a cellular telephone battery  100 , the GPS receiver  54 , and the two-way pager  56 . Controlling electronics  102 , which are preferably a programmed digital signal processor (DSP), interact with the GPS receiver  54  and the two-way pager  56  to coordinate the transfer of the position or location information produced by the GPS receiver to the two-way pager  56  and to initiate the transmission of the position or location information on the reverse paging channel in response to an external paging message that is sent to the two-way paging unit  56 . The GPS receiver  54  has its own GPS antenna  55  and the two-way pager  56  has its own antenna  57 . However, both the GPS receiver  54  and the two-way pager  56  could share a common antenna.  
     [0029] In addition, the position sensing system  52  includes a “panic” button  104  that causes the controlling electronics  102  to initiate the transmission of the position or location information without receiving a requesting page. The panic button  104  is useful for a user who cannot make a 911 cellular or landline call and wishes to alert the location determination service  64  of their present location. Such information may cause emergency personnel to be rushed to their location or may simply be used to update a database with the user&#39;s current location. Such a database can be accessed by others via a computer or telephone in order to keep track of a particular person.  
     [0030] As will be appreciated, the present invention is not limited to use with cellular telephones. Position sensing systems  52  of the type described above can be placed on virtually any item or carried by people to determine their current position and to transmit the position information back to a central service. Such devices can be placed on cars, delivery vehicles, shipping containers, packages, or any other object whose position is to be determined. In addition, such devices can be placed with elderly or other persons suffering from memory lapses or diseases who may become lost or disoriented.  
     [0031]FIG. 4 illustrates an embodiment of the invention that is not connected to a cellular phone system. A requester can access the location determination service  64  to determine the location of a position sensing device  52  via a computer system  124  that is coupled to the location determination service via a computer communication link. Alternatively, a requestor can access the location detection service  64  via a telephone  126  and speak to an operator or voice recognition unit in order to determine the location of a position-sensing device  52 . Alternatively, a requester can access the location detection service  64  via a radio communication link using a wireless personal digital assistant  128 , such as the Palm VII® brand connected organizer, or a two-way pager. To determine the location of the position sensing device  52 , the location determination service  64  interacts with the two-way paging system  68  to transmit a page to the two-way pager  56  that is included within the position sensing system  52 . The two-way pager  56  interacts with the GPS receiver  54  that receives position information from the GPS satellites  70 ,  72 ,  73 . The position or location information is transmitted on the reverse paging channel back to the two-way system  68 . The two-way system  68  forwards the received position or location information back to the location determination service.  
     [0032] As discussed above, to improve the accuracy of the location information provided to a requester, the location determination system  64  interacts with a differential GPS system  77 . The differential GPS system  77  receives position information from one or more GPS towers  77 A,  77 B, whose position is precisely known by survey. The position information received from each of the GPS towers  77 A,  77 B is compared with the actual known position of these towers. The differential GPS system  77  therefore calculates error corrections which are used to adjust the actual location of a position sensing system  52  located in the vicinity of a GPS tower  77 A or  77 B. Typically, the correction factors calculated for the GPS towers  77 A,  77 B are valid for relatively large geographic area surrounding the tower. For example, the same correction can be used within  300  miles surrounding each of the GPS towers  77 A,  77 B.  
     [0033] As with the examples described above, depending upon the processing power at the position sensing system  52 , the location of the position sensing system  52  may be determined by the GPS receiver  54 . Alternatively, the location detection service  64  may receive the position information from the two-way paging system  68  and provide the position information to the location server  75 , which calculates the location including the correction determined by the differential GPS system  77 . If a map is required showing the location of the position sensing system  52 , the location data can be provided to a GIS layer and data service  74 , which produces a map showing the location of the position sensing system  52 .  
     [0034] As indicated above, the database  66  stores profile information for each user of the location detection service. For example, a carrier of a position sensing system  52  may wish to activate a button on the two-way pager  56  that causes his or her current location to be stored in the database and accessed by a few key individuals. What to do with the location information and the identity of the users and their passwords as to who can access the information are therefore stored in the database  66 . Alternatively, if the user presses another button on the two-way pager  56 , the location database  66  stores a rule that causes the location determination service  64  to contact an emergency agency and have emergency personnel dispatched to the user&#39;s location. In addition, the database  66  may store a physical description of the carrier of the position-sensing device  52  so that this information can be given to emergency personnel if desired.  
     [0035] As indicated above, the position sensing system  52  has an improved ability to detect GPS signals quickly and in relatively difficult locations, such as in buildings, by storing a set of access frequencies on which the GPS signals are likely to be received. This is accomplished by analyzing the GPS signals that are received by a particular GPS tower  77 A,  77 B. Based on the proximity of the position sensing system  52  to one of these GPS towers, the information required by the GPS receiver  54  to narrow the search for the GPS signals is periodically forwarded to the GPS receiver using the paging system  68 .  
     [0036] While the preferred embodiment of the invention has been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit of the invention. For example, the panic button  104  could be configured to trigger in response to a signal from a sensor placed on or in a person&#39;s body. For example, a pacemaker could send a radio frequency signal when its battery is getting low that would be received by the panic button  104  in order to trigger an emergency call. Similarly, sensors that monitor blood sugar or other functions could be used.  
     [0037] In some instances, the GPS receiver may not be able to receive signals from the GPS satellites. In that case, a paging transceiver can act as a surrogate to determine the location of the position sensing system  52 . The paging service  68  knows which paging transceiver is communicating with the two-way pager  56  of the position sensing system  52 . Because the location of the paging transceiver is known, that location can be used as a surrogate for the location of the position sensing system (although with less accuracy than the location determined from the GPS signals). The surrogate location information may be stored in a database with a flag or other indicator that indicates the fact that the location is based on the location of the paging transceiver. The location can be updated if a more accurate determination is made based on the GPS signals. Alternatively, when the user&#39;s two-way pager begins communicating with another paging transceiver, the location of the new paging transceiver is adopted as the location of the position sensing system and the new location is updated in the database.  
     [0038] In yet another alternative embodiment of the invention, the surrogate location information can be based on other devices whose position is known. For example, wireless devices that operate according to the Bluetooth™ protocol are being developed. These devices have the ability to communicate with other Bluetooth-compatible devices over relative short distances. The specifications for the Bluetooth protocol can be found at the Web site www.bluetooth.com. The position sensing systems  52  can be equipped to interact with Bluetooth™ transceivers whose position is known. A Bluetooth™ transceiver provides the position sensing system with an identifier that can be used to determine the location of the transceiver. The position sensing system forwards the identifier to the location determination service to determine the location of the transceiver and to use the location as a surrogate for the location of the position sensing system. Alternatively, the Bluetooth™ transceiver may provide the position sensing system with its actual location instead of an identifier from which the location can be determined.  
     [0039] While the preferred embodiment of the invention has been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.