Abstract:
A system and method allow an authorized Service Application or an authorized network entity to retrieve a geographic position of a mobile station. A home Positioning Node for receiving a mobile station&#39;s geoposition request from the Service Application and for generating a Positioning Request message including a home Positioning Node identification parameter to a serving Positioning Node. The serving Positioning Node validates the home Positioning Node identification parameter prior to sending the geographic position of the mobile station to the Service Application. The home Positioning Node further accesses and stores data in an internal database. An anchor Switching Node for receiving, forwarding, processing, generating and sending Positioning Requests. The Anchor Switching Node further supports a mobile station&#39;s hand/off, retrieves the geographic position of the mobile station, and sends it to the authorized network entity.

Description:
PRIORITY STATEMENT UNDER 35 U.S.C S.119(e) &amp; 37 C.F.R. S.1.78 
   This non-provisional patent application claims priority based upon the prior U.S provisional patent application entitled “ENHANCEMENTS TO LOCATION-BASED SERVICES FUNCTIONALITY IN A RADIO TELECOMMUNICATION NETWORK”, application Ser. No. 60/262,092, filed Jan. 16, 2001, in the names of Susan Anctil, Jose Arturo Arreaga Garza and Lan Tran. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a system and method for retrieving the geographic position of a mobile station in a radio telecommunication network. 
   2. Description of the Prior Art 
   Nowadays, the mobility of a mobile subscriber is an important issue in a radio telecommunication network. It is essential that services for which a mobile station (MS) user has subscribed in his home network follow him whenever he roams in a network or hands off to another network. The mobility issue is well known in the art and described in a plurality of standards such as in the American National Standards Institute (ANSI). The ANSI-41 protocol defines the MS geographic position retrieval for a roaming subscriber. This allows providing a MS geographic position to service applications (SA) such as law enforcement, emergency services (e.g. 9-1-1 calls) and location-based services. 
   However, before providing the MS geographic position to service applications, an implementation of a MS location functionality has to be done in the radio telecommunication network. In a radio telecommunication network that follows the ANSI-41 protocol, a mobile switching center (MSC) provides and sends geographic location data of the MS to a mobile positioning center (MPC). A position determining entity (PDE) then calculates the geographic position of the MS by using geographic location data sent by the MSC. The MPC stores that geographic position and renders it available to authorized network entities. 
   Today, with the introduction of several service applications and various systems, it can be difficult for network operators to provide a high level of security. Consequently a mobile subscriber&#39;s privacy is questionable. It is described in a plurality of standards that a mobile subscriber is allowed to restrict the access to his geographic position. More particularly, in the ANSI-41 protocol a subscriber can activate/deactivate the presentation of his position. As an example, Location Information Restriction (LIR) restricts presentation of a MS position information in a radio telecommunication network. 
   There are two different aspects regarding the control of a mobile subscriber on his location information privacy. In a first aspect, the MS geographic position can be retrieved with the approbation of the MS user. A MS user can authorize a network operator or a service provider for retrieving his geographic position upon subscribing to available and offered services (e.g. location-based services) in his home network. In a secondary aspect, the MS geographic position can be retrieved without the approbation of the MS user (law enforcement or emergency services (e.g. 9-1-1 calls)). As known today, a plurality of governments from different countries have adopted laws regarding the implementation of these service applications in radio telecommunication networks. 
   Then, in a way to restrict the access to a mobile subscriber&#39;s location, it is necessary to make sure that the MS geographic position is requested by an approved network entity. It is essential for a network operator to certify that the network entity is therefore one that is authorized to ask for the MS geographic position. Consequently, there is a need to improve the security aspect related to geographic positioning of mobile stations and the providing of such information to service applications. The present invention provides a solution to this effect. 
   SUMMARY OF THE INVENTION 
   It is therefore one broad object of this invention to provide a high level of security for a geographic position of a Mobile Station (MS) by rendering the MS geographic position available only to authorized network entities or Service Applications. 
   More particularly, the present invention provides a system and method for retrieving the geographic position of the MS. The system and method comprise a home Positioning Node (PN) for receiving a MS Geoposition Request from a Service Application (SA), and for generating a Positioning Request message including a home Positioning Node identification parameter. The system and method further comprise a serving PN for receiving the Positioning Request, and for validating the home Positioning Node identification parameter prior to sending the geographic position of the MS to the SA. The home PN comprises an Input/Output Unit for receiving a MS Geoposition Request from the SA, for sending an Authorization Request message for requesting an authorization for the MS Geoposition Request to a Global Database (GD), for receiving an Authorization Response from the GD, for sending a Positioning Request message including the home Positioning Node identification parameter to a serving PN, and for receiving a Positioning Response from the serving PN. If a hand off has occurred, the system and method also comprises an anchor Switching Node (SN). The anchor SN comprises an Input/Output Unit for receiving the Positioning Request from the home PN via an anchor PN, for forwarding the Position Request to a serving PN via a serving SN, and for sending a Positioning Response to the anchor PN. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a more detailed understanding of the invention, for further objects and advantages thereof, reference can now be made to the following description, taken in conjunction with the accompanying drawings, in which: 
       FIG. 1  is a message flow diagram illustrating the flow of messages in accordance with the invention for retrieving the geographic position of a Mobile Station in a Radio Telecommunication Network; 
       FIG. 2  is a message flow diagram illustrating the flow of messages in an ANSI-41 network; 
       FIG. 3  is a block diagram illustrating a Positioning Node; 
       FIG. 4  is a flow chart illustrating positioning of the Mobile Station in the Radio Telecommunication Network; 
       FIG. 5  is a block diagram illustrating a Switching Node; and 
       FIG. 6  is a flow chart illustrating retrieval of the geographic position of the Mobile Station in the Radio Telecommunication Network. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The following abbreviations are being used throughout the present application: 
   GD: Global Database 
   HLR: Home Local Register 
   ISPOSREQ: Intersystem Positioning Request 
   ISPOSREQFWD: Intersystem Positioning Request Forward 
   LCS: Location Services 
   LD: Location Detector 
   MPC: Mobile Positioning Center 
   MS: Mobile Station 
   MSC: Mobile Switching Center 
   PDE: Position Determining Entity 
   PN: Positioning Node 
   POSREQ: Positioning Request 
   RTN: Radio Telecommunication Network 
   SA: Service Application 
   SN: Switching Node 
   Reference is now made to  FIG. 1  there is shown a message flow diagram illustrating the flow of messages in the present invention for retrieving the geographic position of a Mobile Station (MS) (not shown) in a Radio Telecommunication Network (RTN)  100 . The RTN  100  comprises a Home network  104 , an Anchor network  108  and a Serving network  112 . As well, each network (Home network  104 , Anchor network  108  and Serving network  112 ) comprises different entities, which realize the steps of the invention. The Home network  104  comprises a Positioning Node (PN)  116  and a Global Database (GD)  120 . The Anchor network  108  comprises a PN  124  and a Switching Node (SN)  128  while the Serving network  112  comprises a PN  132 , a Location Detector (LD)  136  and a SN  140 . The MS is registered in the Home network  104 . If the MS is located in the Home network  104 , the Home network  104  is called the serving network of the MS. However, the MS can roam in different networks. A network where the MS roams becomes the serving network of the MS. However, if the MS hands off to another network the original serving network will be called the anchor network and the new network where the MS is located becomes the serving network. 
   The flow of messages starts when a Service Application (SA)  144  requests the geographic position of an MS. The SA  144  sends to the home PN  116  an MS Geoposition Request  148  for requesting the geographic position of the MS. The home PN  116  obtains data from the MS Geoposition Request  148  and authenticates the SA  144 . After that authentication, the PN  116  sends an Authorization Request  152  including a home Positioning Node identification parameter (home PNID  154 ) to the GD  120  for authorizing the MS Geoposition Request  148  and for obtaining data. The GD  120  authorizes the request and sends an Authorization Response  156  to the home PN  116 . The Authorization Response  156  comprises a serving SN identification parameter and an associated serving PN network address. Subsequently, the PN  116  sends a Positioning Request  160  including the home Positioning Node identification parameter (home PNID  154 ) and the serving SN identification parameter to the identified PN  124 . The PN  124  uses the home Positioning Node identification parameter (home PNID  154 ) to determine if the Positioning Request  160  has been originated from an authorized network entity. Following this determination, the PN  124  uses the received serving SN identification parameter for sending a Positioning Request  164  to the SN  128 . The SN  128  is capable of determining if the MS has handed off to another network. If the MS has handed off to another network, the SN  128  forwards data obtained in the Positioning Request  164  in a Forwarded Positioning Request  168  to the new serving SN  140 . Next, the serving SN  140  sends a Positioning Request  172  including the home Positioning Node identification parameter (home PNID  154 ) to the serving PN  132 . The serving PN  132  uses the home Positioning Node identification parameter (home PNID  154 ) to determine if the Positioning Request  160  has been originated from an authorized network entity (home Positioning Node  116 ). Following this determination, the serving PN  132  uses data obtained in the Positioning Request  172  for selecting an appropriate LD (LD  136 ), which determines and sends the geographic position of the MS to the PN  132 . More particularly, the selected LD  136  determines the geographic position of the MS by communicating with the SN  140  and the PN  132 , “(PN  132 -SN  140 -LD  136 ) Signaling”  174 . Next, the serving PN  132  replies to the Positioning Request  172  with a Positioning Response  176  including the geographic position of the MS (geopos  178 ). The SN  140  is then able to answer to the Forwarded Positioning Request  168  received from the anchor SN  128  with a Forwarded Positioning Response  180  including the geographic position of the MS (geopos  178 ). The SN  128  then answers the Positioning Request  164  from the PN  124  with a Positioning Response  184  including the geographic position of the MS (geopos  178 ). Following that message, the PN  124  returns the geographic position of the MS (geopos  178 ) to the PN  116  in a Positioning Response  188 . Afterwards, the PN  116  sends a MS Geoposition Response  192  including the geographic position of the MS (geopos  178 ) to the requesting SA  144 . 
   The invention can be applied to a plurality of telecommunication network protocols known in the art. As an example we refer now to  FIG. 2 . In  FIG. 2  there is shown a message flow diagram similar to  FIG. 1 , but now applied to the signaling in an ANSI-41 network. The ANSI-41 network  200  comprises a Home network  204 , an Anchor network  208  and a Serving network  212 . As well, each network (Home network  204 , Anchor network  208  and Serving network  212 ) comprises different entities, which realize the steps of the invention. The Home network  204  comprises a Mobile Positioning Center (MPC)  216  and a Home Location Register (HLR)  220 . The Anchor network  208  comprises a MPC  224  and a Mobile Switching Center (MSC)  228  while the Serving network  212  comprises a MPC  232 , a Position Determining Entity (PDE)  236  and a MSC  240 . The MS (not shown) is registered in the Home network  204 . If the MS is located in the Home network  204 , the Home network  204  is called the serving network of the MS. However, the MS can roam in different networks. A network where the MS roams becomes the serving network of the MS. However, if the MS hands off to another network the original serving network will be called the anchor network and the new network where the MS is located becomes the serving network. 
   The flow of messages depicted in  FIG. 2  starts when a Location Services Client (LCS Client)  244  requests the geographic position of an MS. The LCS Client  244  sends to the MPC  216  an Intersystem Positioning Request (ISPOSREQ)  248  for retrieving the geographic position of the MS. The ISPOSREQ  248  includes a Position Quality of Service parameter (PQoS) for specifying the required quality of service for the MS position, a LCS Client identification parameter (LCSCID) for identifying the LCS Client  244  and authentication data parameter (Authentication_Data) for authenticating the LCS Client  244  in the MPC  216 . With the parameters and data included in the ISPOSREQ  248 , the MPC  216  authenticates the LCS Client  244  and verifies that the LCS Client  244  is authorized to request the MS geographic position. Next, the MPC  216  sends to the HLR  220  a Positioning Request (POSREQ)  252  message including the LCSCID and a home MPC identification parameter (MPCID) for authorizing the ISPOSREQ  248 , and for obtaining data. More particularly, the HLR  220  validates the identity of the LCS Client  244  using the received LCSCID and a list of valid LCS Clients, authorizes the ISPOSREQ  248 , and sends a posreq  256  to the home MPC  216  for authorizing the ISPOSREQ  248 . The posreq  256  comprises an MS identification parameter (MSID) for identifying the MS, a network address (MPCADRR) of the MPC  224  associated with the MSC  228  where the MS last registered and a MSC identification parameter (MSCID) for identifying the MSC (MSC  228 ). Subsequently, the MPC  216  sends an ISPOSREQ  260  to the identified MPC  224 . The ISPOSREQ  260  comprises the received PQoS, MSID, MSCID, LCSCID and home MPC identification parameter (MPCID(home)). The MPC  224  uses the MPCID(home) to verify that the ISPOSREQ  260  has been originated from an authorized entity (MPC  216 ). Following this determination, the MPC  224  sends an ISPOSREQ  264  to the MSC  228  by using the received MSCID. The MSC  228  is capable of determining if the MS has handed off to another network. If the MS has handed off to another network, the MSC  228  forwards the required parameters obtained in the ISPOREQ  264  (MSID, LCSCID, PQOS, and MPCID(home)) in an Intersystem Positioning Request Forward (ISPOSREQFWD)  268  to the new serving MSC  240 . The serving MSC  240  sends to the associated MPC  232  an ISPOSREQ  272  including the MS information (MOBINFO) needed to determine the MS geographic position, the MS positioning capabilities (MPCAP parameter), the MSID, the received PQoS and the MPCID(home). The MPC  232  uses the MPCID(home) parameter to verify that the request for the MS geographic position has been originated from an authorized entity (MPC  216 ). Following this determination, the serving MPC  232  uses the PQoS and the MPCAP parameter for selecting an appropriate PDE (PDE  236 ), which determines and sends the geographic position of the MS to the MPC  232 . More particularly, the selected PDE  236  determines the geographic position of the MS by communicating with the MSC  240  and the MPC  232 , “(MPC  232 -MSC  240 -PDE  236 ) Signaling”  274 . Subsequently, the MPC  232  replies to the ISPOSREQ  272  with an isposreq  276  including the geographic position of the MS (POSINFO parameter). Upon receiving this information, the MSC  240  answers the ISPOSREQFWD  268  by sending an isposreqfwd  280  including the received POSINFO parameter to the MSC  228 . The MSC  228  returns the POSINFO parameter to the MPC  224  by sending an isposreq  284 . The MPC  224  returns the POSINFO parameter to the MPC  216  in an isposreq  288 . Afterwards, the MPC  216  generates and sends an isposreq  292  including the geographic position of the MS (POSINFO parameter) to the requesting LCS Client  244 . 
   Reference is now made to  FIG. 3 , which is a block diagram illustrating the PN  116 ,  FIG. 4 , which is a flow chart that demonstrates the steps for positioning the MS in the RTN  100  and further to  FIG. 1 . The PN  116  comprises an Input/Output Unit  300  for receiving messages from other network entities and Service Applications, and sending generated messages, a Processor  310  for processing messages, a Message Generator  320  for generating outgoing messages, an Acknowledge functionality (ACK)  330  for accessing an internal database, and a Position Database  340  for storing the geographic position of mobile stations. At step  400 , the PN  116  receives the MS Geoposition Request  148  from the SA  144  at the Input/Output Unit  300 . At step  410 , the Processor  310  verifies that the SA  144  is authorized to request the MS geographic position. If the SA  144  is authorized, the PN  116  will generate and send the Authorization Request  152  to the GD  120  at step  420 . If not, the PN  116  will deny the MS Geoposition Request  148 , generate and send a message to the requesting SA  144  at step  430 . The following steps are executed in the case that the SA  144  is an authorized SA. At step  440 , the PN  116  receives an Authorization Response  156  from the GD  120 . Subsequently, the PN  116  generates the Positioning Request  160  to the PN  124 , at step  450 . At step  460 , the PN  124  uses the home Positioning Node identification parameter (home PNID  154 ) included in the Positioning Request  160  to determine if the Positioning Request  160  has been originated from an authorized network entity. If the network entity (PN  116 ) is not authorized, the PN  124  will generate a message for denying the request (step  430 ). If the request has been originated from an authorized entity, the PN  124  generates the Positioning Request  164  to its associated SN  128  (step  470 ) and receives the Positioning Response  184  from the SN  128  (step  480 ) prior to sending the Positioning Response  188  to the home PN  116 , at step  485 . The Processor  310  processes the Positioning Response  188  received from the PN  124  and, by using the ACK  330 , stores the geographic position data of the MS (geopos  178 ) obtained from the Positioning Response  188  in the Position Database  340 . Next, the geographic position data of the MS is returned to the requesting SA  144  at step  490 . More particularly, the Processor  310  processes the request from the SA  144  and the ACK  330  allows accessing the geographic position of the MS stored in the Position Database  340 . 
   Reference is now made to  FIG. 5 , which is a block diagram illustrating the SN  128 ,  FIG. 6 , which is a flow chart that demonstrates the steps for retrieving the geographic position of the MS in the RTN  100 , and further to  FIG. 1 . The SN  128  comprises an Input/Output Unit  500  for receiving messages from other network entities and for sending generated messages, a Processor  510  for processing messages, a Presence Determiner  520  for determining that a MS has handed off to another network and a Message Generator  530  for generating outgoing messages. At step  600 , the SN  128  receives the Positioning Request  164  from the PN  124 . At step  610 , the Presence Determiner determines that the MS has handed off to another network. Following this determination, the SN  128  forwards data obtained from the Positioning Request  164  to the new serving SN  140  in the Forwarded Positioning Request  168 , at step  620 . Next, the SN  140  sends the Positioning Request  172  to the new serving PN  132  (step  630 ). At step  635 , the PN  132  uses the home Positioning Node identification parameter (home PNID  154 ) to verify if the Positioning Request  172  has been originated from an authorized network entity (PN  116 ). If the Positioning Request  172  is not from an authorized network entity, the PN  132  will deny the Positioning Request  172  (step  640 ). The following steps are executed in the case that the PN  116  is an authorized entity. At step  650 , the PN  132  selects an appropriate LD (LD  136 ) based on the data obtained from the Positioning Request  172 . In return, at step  660  the LD communicates with the serving SN  140  and the serving PN  132  for determining and sending the geographic position of the MS (geopos  178 ) to the PN  132 . At step  665 , the PN  132  sends the geographic position of the MS (geopos  178 ) in the Positioning Response  176  to the SN  140 . Following this message, the SN  140  sends the obtained geographic position of the MS (geopos  178 ) in the Forwarded Positioning Response  180  to the anchor SN  128 , at step  670 . Afterwards, at step  680 , the anchor SN  128  processes and generates the Positioning Response  184  including the geographic position of the MS (geopos  178 ) to the requesting PN  124 . 
   Although several preferred embodiments of the method and system of the present invention have been illustrated in the accompanying Drawings and described in the foregoing Detailed Description, it will be understood that the invention is not limited to the embodiments disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the spirit of the invention as set forth and defined by the following claims.