Abstract:
Systems and methods that effectively and efficiently provide a communications interface between remotely located GMLC and SMLC nodes. A method according to the invention may include receiving a location request and location data, arranging the location request and the location data into a predefined format; calculating a position of a mobile unit; arranging data indicative of the calculated position into a predefined format; and sending the arranged data over the wireless network. A system according to the invention may include means for receiving a location request and location data; means for arranging the location request and the location data into a predefined format that is useable by a servicing mobile location center; means for calculating a position of the mobile unit; means for arranging data indicative of the calculated position into a predefined format; and means for sending the arranged data over a wireless network.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of United States Provisional Patent Application entitled “Method and Apparatus for Location Services Routing Between GMLC and SMLC” filed Nov. 14, 2003, Ser. No. 60/520,023 which is hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     The present invention relates generally to telecommunication systems, and more particularly to telecommunication systems that receive and process location queries from mobile units or remote applications to determine the position of a particular mobile unit within a communications network.  
         [0003]     The Global System for Mobile Communications (GSM) is a popular standard currently in use to provide wireless communications. This standard was developed primarily for voice communications, but is also frequently used to provide data services. The General Packet Radio Service (GPRS) is an extension of the GSM standard that provides data services to GSM mobile devices. Typical applications for GPRS include Internet browsing, wireless e-mail, and text messaging.  
         [0004]     The GSM standard is capable of providing a variety of information services to subscribers. Location Services (LCS) is one example of an information service that GSM provides. LCS allows a subscriber or remote application to obtain or determine the location of a GSM mobile unit operating within the GSM network. The location may be determined by the network, based on measurements supplied by the mobile unit, or may be determined by the mobile unit itself and communicated to the network. Various approaches to position estimation may be used, including Uplink Time of Arrival (TOA), Enhanced Observed Time Difference (E-OTD), and assisted Global Positioning System (GPS).  
         [0005]     In a standard architecture GSM system, a centralized server known as the Serving Mobile Location Center (SMLC) manages the overall coordination and scheduling of resources required to perform the tasks associated with positioning a mobile unit. It may also calculate the final location of the mobile unit and estimate the accuracy of the position measurement. In performing these functions, the SMLC exchanges information with other entities within the network, such as the mobile unit and/or a location measuring unit or application. The location information may be the position of the mobile unit, measurements from which the position of the mobile unit may be determined, or data otherwise useful in determining the position of the mobile unit.  
         [0006]     In a conventional GSM system, the SMLC server communicates with a Gateway Mobile Location Center (GMLC), which is typically the first point at which an external LCS client application accesses a Public Land Mobile Network (PLMN) when providing location services. The GMLC communicates the queries received from the mobile unit to the SMLC so it may perform certain positioning functions as well as provide an initial rough estimate of the mobile unit&#39;s location (such as the particular cell site the mobile unit is in).  
         [0007]     In the past, it was common for the functionality of the SMLC and the GMLC to be combined into the same physical node. With this configuration, the SMLC and GMLC applications would typically communicate directly with one another according to standard SS7 communication techniques. However, recently, as communication networks have become more distributed in nature, it is becoming more common for the SMLC and the GMLC to be physically remote from one another.  
         [0008]     Accordingly what is needed is an efficient and effective way for an SMLC node to interface with a physically remote GMLC node and vice versa.  
         [0009]     In view of the foregoing, it would therefore be desirable to provide systems and methods that effectively and efficiently provide a communications interface between remotely located GMLC and SMLC nodes.  
       SUMMARY OF THE INVENTION  
       [0010]     It is therefore an object of the present invention to provide systems and methods that effectively and efficiently provide a communications interface between remotely located GMLC and SMLC nodes.  
         [0011]     These and other objects of the invention are provided in accordance with the principles of the present invention by providing systems and methods that effectively and efficiently provide a communications interface between remotely located GMLC and SMLC nodes. A method according to a preferred embodiment of the invention may include receiving a location request and location data at a public land mobile network. The public land mobile network may include a servicing mobile location center and a gateway mobile location center. The method may also include arranging the location request and the location data into a predefined format that is useable by the servicing mobile location center; calculating a position of the mobile unit using the servicing mobile location center and/or the gateway mobile location center; arranging data indicative of the calculated position into a format recognizable by the mobile unit, the location application, and/or the location client; and sending the arranged data over the wireless network to the mobile unit, the location application, and/or the location client.  
         [0012]     A system according to a preferred embodiment of the present invention may include means for receiving a location request and location data; means for arranging the location request and the location data into a predefined format that is useable by a servicing mobile location center; means for calculating a position of the mobile unit; means for arranging data indicative of the calculated position into a format recognizable by the mobile unit, a location application, and/or a location client; and means for sending the arranged data over a wireless network to the mobile unit, the location application, and/or the location client. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     The above and other objects and advantages of the present invention will be apparent upon consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which like reference numbers refer to like parts throughout, and in which:  
         [0014]      FIG. 1  shows a generalized block diagram of a system constructed in accordance with the principles of preferred embodiments of the present invention for providing a communications interface between remotely located GMLC and SMLC nodes.  
         [0015]      FIG. 2  is a block diagram illustrating an alternate preferred embodiment of the system shown in  FIG. 1 .  
         [0016]      FIG. 3  is flow chart illustrating some of the steps involved in providing a communications interface between remotely located GMLC and SMLC nodes in accordance the principles of preferred embodiments of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0017]      FIG. 1  shows a generalized block diagram of a system  100  for providing a communications interface between a remotely located GMLC node  108  and an SMLC node  110 . The system may include a mobile unit  102 , a wireless communications network  104  which is capable of operating according to a particular communications standard (e.g., GSM), a gateway interface  106  capable of interfacing with wireless communications network  104 , a location application  112 , and a location client  114 .  
         [0018]     In operation, mobile unit  102 , which may be any suitable mobile communications device such as a cellular telephone, a personal digital assistant (PDA), a handheld PC, a Blackberry™, etc. may issue a position or location request to wireless communication network  104 . Network  104 , which preferably includes GSM and GPRS communication capabilities, receives this request and communicates it to gateway  106  which may function as interface between wireless communication network  104  and the components typically found incertain portions of a Public Land Mobile Network (PLMN). In some embodiments, the PLMN may include GMLC  108 , SMLC  110 , location application  112  as well as other known telecommunications components (not shown).  
         [0019]     Generally speaking, wireless network  104  includes the resources required to support GPRS functions. Moreover, in some embodiments, network  104  may provide network access control, which is the means by which a user of mobile unit  102  connects to a telecommunications network in order to use the services of that network.  
         [0020]     Gateway  106  may include software and/or hardware that allows it to function as a Wireless Application Gateway (WAP) and may also include similar resources or otherwise be configured to allow it to provide Push Proxy Gateway (PPG) functions. However, it will be understood that any other suitable methods, communication or data transfer standards, or other protocols may be used, if desired, by gateway  106  to communicate with wireless network  104 .  
         [0021]     Location application  112  may be any commercial or proprietary application or system suitable for assisting in determining the position of mobile unit  102 . For example, location application  112  may include or communicate with certain location systems that employ Global Positioning System (GPS) measurements or other observation or measurement-based techniques such as Uplink Time of Arrival (TOA), Enhanced Observed Time Difference (E-OTD), suitable for providing information to SMLC  110  or any other system in order to assist in locating mobile unit  102 .  
         [0022]     Location client  114  may be any suitable external client process requesting location information regarding mobile unit  102 . For example, location client  114  may be a software tracking application that informs users of the location of a particular mobile unit  102 .  
         [0023]     As shown in system  100  of  FIG.1 , gateway  106  may send location requests to location application  112  via GMLC  108  and SMLC  110 . In some embodiments, this request may include location data such as pseudo-range measurements from mobile unit  102  that provides an approximation of where the particular mobile unit is located within a particular cell site. This location data may also be used to aid in the calculation of a more precise location of the mobile unit&#39;s position. As state above, this information may be used to approximate the location of mobile unit  102  without further processing by location application  112 , location client  114 , or SMLC  110  and may be useful in emergency situations when subsequent communications with mobile unit  102  is lost.  
         [0024]     In the embodiment of  FIG. 1 , location application  112  and/or location client  114  may interface directly (or through some intermediate circuitry (not shown)) with GMLC  108  to coordinate the positioning and control transactions with SMLC  110  necessary to complete a location request. This may be accomplished using some of the positioning and control messages discussed below. Subsequently, GMLC  108  may communicate the results of these transactions to mobile unit  102 , location application  112 , and/or location client  114  thereby providing the requested location information/data. Such information/data may be integrated into a mapping application available to mobile unit  102 , location application  112 , and/or location client  114  such that the location information makes sense to the user (discussed in more detail below).  
         [0025]     In other embodiments, location application  112  and/or location client  114  may be external application requesting the location information from mobile unit  102 . In this case, the request may be processed generally as described above with GMLC  108  and SMLC  110  performing the location calculations (with or without information/data from mobile device  102 ) with the results being provided to application  112  and/or client  114 .  
         [0026]     Some of the positioning and control messages that may be used for GMLC  108  to communicate with a remotely located SMLC  110  (and vice versa) in accordance with the principles of a preferred embodiment of the present invention include the following:  
         [0027]     RSP Positioning Messages: 
        RSP Perform_Location_Request     RSP Perform_Location_Response     RSP Perform_Location_Abort     RSP Measure_Position_Request     RSP Measure_Position_Response     RSP Reset     RSP Abort     RSP Reject        
 
         [0036]     In some embodiments, RSP positioning messages may have the following structure:  
                                                     Message Begin Flag             1 byte = 0xFF             Message Length Field           1 byte = lengths of the message after this field           RSP Positioning Message Type: (1 byte)           RSP Perform Location Request,           RSP Perform Location Response,           Abort, Reset, Protocol_Error,           Termination             Transaction Identifier (6 bytes)             Information Elements/Data                      
 
         [0037]     RSP Control Messages: 
        RSP_Appication_context_req     RSP_Appication_context_res     RSP_Application_check_alive     RSP_Application_check_alive_ack     RSP_Protocol_Error        
 
         [0043]     In some embodiments, RSP control messages may have the following structure:  
                                                     Message Begin Flag             1 byte = 0xFF             Message Length Field           1 byte = lengths of the message after this field           RSP Control Message Type: (1 byte)           RSP_Application_Context           RSP_Application_Context_Response           RSP_Check_Alive           RSP_Check_Alive_Ack             Information Elements/Data                      
 
         [0044]     The set of messages and the message structures listed above may be thought of as defining a new communication protocol that may sometimes be referred to as the Remote SMLC Protocol (RSP). Some or all of the above messages (and any results or computations associated therewith) may be transported back and forth between remotely located GMLC and SMLC nodes, thus providing an effective and efficient way for these platforms to communicate and cooperate with one another in providing location services to a mobile unit despite being physically separate from one another.  
         [0045]     System  100  may be configured such that the messages and structures shown above may be native to both GMLC  108  and SMLC  110  or may require some intermediate processing to be understood by one or both of these processes. In the case where intermediate processing is required, e.g., such as when certain legacy systems are updated, either SMLC  110  or GMLC  108  may be reprogrammed to convert or accept the RSP messages above, or in some embodiments, may require the installation of translation or conversion hardware/software to convert these messages to a desired format (not shown).  
         [0046]     In addition, in some embodiments of the present invention, standardized GPRS position and control messages may be converted into the RSP messages above by using the information contained within the messages themselves and rearranging information into the new format as shown in the illustrative examples below:  
                                   Standard Positioning Messages   Corresponding RSP messages                   Perform_location_request   RSP Perform_location_request       (BSSMAP-LE)       Perform_location_response   RSP Perform_location_response       (BSSMAP-LE)       RRLP Measure_position_request   RSP Measure_position_request       RRLP Measure_position_response   RSP Measure_position_response                  
 
         [0047]     Additional illustrative message arrangements and formats may be as follows:  
                                                           3.1.1.1 RSP Perform Location Request message            Information               Length in       element   Type/Reference   Presence   Format   octets               Message type   See 0   M   V   1       Transaction_ID   See 0   M   V   6       Location Type                                 M   TLV   3-4               Cell Identifier                                 M   TLV   3-10               Classmark Information Type 3                                 O   TLV   2-n               LCS Client Type                                 C   TLV   3               Chosen Channel                                 O   TLV   2-n               LCS Priority                                 O   TLV   3               LCS QoS                                 O   TLV   6               GPS Assistance Data                                 O   TLV   3-n               BSSLAP APDU                                 O   TLV   2-n               Response Time   See 0   O   TV   2       Generic   See 0   O   TLV   3-n       Information                                              Ref: BSSMAP-LE spec Rel ′99 49.031 v 8.6.0 Sec 9.1.1-9.1.8                  
 
         [0048]                                                                3.1.1.2 RSP Perform Location Response message            Information               Length in       element   Type/Reference   Presence   Format   octets               Message type   See 0   M   V   1       Transaction_ID   See 0   M   V   6       Location Estimate                                 C   TLV   2-22               Positioning Data                                 O   TLV   2-n               Deciphering Keys                                 O   TLV   17               LCS Cause                                 O   TLV   3                                              Ref: BSSMAP-LE spec Rel′99 49.031 v 8.6.0 Sec 9.2.1-9.2.4                    
 3.1.1.3 RSP Measure Position Request—Message coding is similar to the RRLP measure position request with additional parameters specifying the RSP Measure Position Request message type and the transaction ID. 
 
 3.1.1.4 RSP Measure Position Response—Message coding is similar to the RRLP measure position response with additional parameters specifying the RSP Measure Position Response message type and the transaction ID. 
 
         [0049]     3.1.1.5 RSP Perform Location Abort/Reset Message  
                                                               Length in       Information element   Type/Reference   Presence   Format   octets                   Message type   See 0   M   V   1       Transaction_ID   See 0   M   V   6       Cause   See 0   M   TV   2                  
 
         [0050]     3.1.1.6 RSP PROTOCLO ERROR Message  
                                                               Information   Type/                       element   Reference   Presence   Format   Length                           Message Type   See 0   M   V   1           Transaction —     See 0   M   V   6           ID           Transaction   See 0   M   TV   2           Error Cause           User   See 0   O   TLV   3 − n           information                      
 
         [0051]     3.1.1.7 RSP TERMINATION Message  
                                                               Information   Type/                       element   Reference   Presence   Format   Length                           Message Type   See 0   M   V   1           Transaction —     See 0   M   V   6           ID           Termination   See 0   M   TV   2           Cause                      
 
 3.1.2 RSP Control Messages 
 
         [0052]     3.1.2.1 RSP APPLICATION CONTEXT Message  
                                                               Information   Type/                       element   Reference   Presence   Format   Length                           Message Type   See 0   M   V   1           Application ID   See 0   M   TV   2                      
 
         [0053]     3.1.2.2 RSP APPLICATION CONTEXT RESPONSE Message  
                                                               Information   Type/                       element   Reference   Presence   Format   Length                           Message Type   See 0   M   V   1           Context Status   See 0   M   TV   2                      
 
         [0054]     3.1.2.3 RSP CHECK ALIVE Message  
                                                               Information   Type/                       element   Reference   Presence   Format   Length                           Message Type   See 0   M   V   1                      
 
         [0055]     3.1.2.4 RSP CHECK ALIVE ACK Message  
                                                               Information   Type/                       element   Reference   Presence   Format   Length                           Message Type   See 0   M   V   1                      
 
         [0056]     3.1.3 Coding of New Message Type on RSP  
                                                   8 7 6 5 4 3 2 1   Message Type                           0 0 0 0 0 0 0 1   RSP Perform Location Request message           0 0 0 0 0 0 1 0   RSP Perform Location Response           0 0 0 0 0 0 1 1   RSP Measure Position Request           0 0 0 0 0 1 0 0   RSP Measure Position Response           0 0 0 0 0 1 0 1   RSP Abort           0 0 0 0 0 1 1 0   RSP RESET           0 0 0 0 0 1 1 1   RSP PROTOCOL ERROR           0 0 0 0 1 0 0 0   RSP TERMINATION           0 0 0 0 1 0 0 1   Reserved           to           0 1 1 1 1 1 1 1           1 0 0 0 0 0 0 1   RSP APPICATION CONTEXT           1 0 0 0 0 0 1 0   RSP APPICATION CONTEXT RESPONSE           1 0 0 0 0 0 1 1   RSP CHECK ALIVE           1 0 0 0 0 1 0 0   RSP CHECK ALIVE ACK           1 0 0 0 0 1 0 1   Reserved           to           1 1 1 1 1 1 1 1                      
 
 3.1.4 Coding of Information Element on RSP 
 
         [0057]     3.1.4.1 Element Identifier  
                                                   Element               Identifier           Coding   Element name                           0000 0000   Reserved           0000 0001   Location Type           0000 0010   Cell Identifier           0000 0011   Classmark Information Type 3           0000 0100   LCS Client Type           0000 0101   Chosen Channel           0000 0110   LCS Priority           0000 0111   LCS QoS           0000 1000   GPS Assistance Data           0000 1001   BSSLAP APDU           0000 1010   Location Estimate           0000 1011   Positioning Data           0000 1100   Deciphering Keys           0000 1101   LCS Cause           0000 1110   Cause           0000 1111   Application ID           0001 0000   Context Status           0001 0001   Transaction Error Cause           0001 0010   User Info           0001 0011   Termination Cause           0001 0100   Generic Information           0001 0101   Reserved           to           1111 1111                      
 
         [0058]     3.1.4.2 Transaction_ID  
                                                                                         8   7   6   5   4   3   2   1                                        Transaction ID value   octet 1           continue   octet 2           continue   octet 3           continue   octet 4           continue   octet 5           continue   octet 6                      
 
 Possible range of Transaction ID value: 
 
 00 00 00 00 00 00 to FF FF FF FF FF FF 
 
         [0059]     3.1.4.3 Response Time  
                                                                                         8   7   6   5   4   3   2   1                                        Element identifier, see 0   octet 1           Timer Value   octet 2                         The Timer Value field is expressed in units of 500 ms.             
 
         [0060]     3.1.4.4 Application ID  
                                                                                                           8   7   6   5   4   3   2   1                                        Element identifier, See 0   octet 1                Application ID   Version   octet 2                      
 
 Coding of Application ID (bits 8-3): 
 
 000001 A-GPS Application 
 
 The Version field (bits 2-1) shall be coded as  00  if not used. If used, it shall be populated with the value assigned by the PDE. 
 
         [0061]     3.1.4.5 Context Status  
                                                                                         8   7   6   5   4   3   2   1                                        Element identifier, See 0   Octet 1           Status   Octet 2                      
 
         [0062]     Coding of Status (bits 8-1):  
                                                       00000000   Reserved           00000001   Allow           00000010   Not Allow           00000011   Not Supported           00000100   Reserved           to           11111111                      
 
         [0063]     3.1.4.6 Transaction Error Cause  
                                                                               3.1.4.6 Transaction Error Cause                                8   7   6   5   4   3   2   1                Element identifier, See 0   octet 1       Cause   octet 2                  
 
         [0064]     Coding of Cause (bits 8-1):  
                                                       00000000   Reserved           00000001   Unknown Transaction           00000010   Duplicated Transaction ID           00000011   Message Synchronization Lost           00000100   Message Rejected           00000101   Invalid Message           00000110   Badly coded Message           00000111   Reserved           to           11111111                      
 
         [0065]     3.1.4.7 User Information IE  
                                                                                         8   7   6   5   4   3   2   1                                        Element identifier, See 0   octet 1           Length   octet 2           The rest of the octet contains User   octets 3 − n           Information data                      
 
         [0066]     3.1.4.8 Cause IE  
                                                                                         8   7   6   5   4   3   2   1                                        Element identifier, See 0   octet 1           Cause value   octet 2                      
 
         [0067]     The cause field is coded as follows:  
                                                       0000 0000   Reserved           0000 0001   Congestion           0000 0010   System Failure           0000 0011   Protocol Error           0000 0100   Data missing in the               positioning request           0000 0101   Location request               aborted           0000 0110   Unexpected data value               in position request           0000 0111   unspecified           0000 1000   Failure or Error in               GMLC                         All unassigned codes are spare.             
 
         [0068]     3.1.4.9 Termination Cause IE  
                                                                                         8   7   6   5   4   3   2   1                                        Element identifier, See 0   octet 1           Cause value   octet 2                      
 
         [0069]     The cause field is coded as follows:  
                                                       0000 0000   Reserved           0000 0001   Normal - unspecified           0000 0010   System Reset                         All unassigned codes are spare.             
 
         [0070]     3.1.4.10 Generic Information IE  
                                                                                         8   7   6   5   4   3   2   1                                        Element identifier, See 0   octet 1           Length   octet 2           The rest of the octet contains   Octet 3 − n           generic information data                      
 
         [0071]     4.0 Abbreviations  
                                                       3GPP   Third Generation Partnetship Oroject           BSC   Base Station Controller           BSSLAP   BSS LCS Assistance Protocol           BSSMAP-LE   BSS Management Application Part LCS               Extension           CR   Change Request           IE   Information Element           IEI   Information Element Identifier           IP   Internet Protocol           Lb   Interface between SMLC and BSC           LCS   Location Service           MS   Mobile Station           QoS   Quality of Service           SCCP   Signaling Connection Control Part           SMLC   Serving Mobile Location Centre           T   (IE format) Type           TCP   Transmission Control Protocol           TLV   (IE format) Type, Length and value           TS   Technical Specification           TV   (IE format) Type and value           V   (IE format) Value only                      
 
         [0072]     The following references are hereby incorporated by reference in their entirety.  
                                       /1/   3GPP TS 43.059       /2/   RFC793, Transmission Control Protocol       /3/   TS 09.031 v6.0.0 or latest: “Base Station System           Application Part; LCS Extension (BSSAP-LE)”       /4/   TS 04.031 RRLP       /5/   TS 03.71                  
 
         [0073]     Returning now to  FIG. 1 , in system  100 , SMLC  110  may include all or most of the functionality required to support location services (LCS). Furthermore, SMLC  110  may manage the overall coordination and scheduling of resources required to perform positioning of a mobile unit  102  and may, in some instances, be referred to as a location server. SMLC  110  may perform the steps necessary to calculate a final location estimate of the mobile unit  102  and the accuracy thereof using known calculation techniques.  
         [0074]     GMLC  108  may also include some of the functionality required to support location services. In some embodiments, GMLC  108  is the first node at which location application  112  and/or location client  114  accesses wireless network  104 . GMLC  108  may perform certain managerial functions associated with signal routing such as request process signal routing information from a home location register to determine how to route response to locations queries and may assist in calculating the final location of mobile unit  102 .  
         [0075]     In one embodiment of the present invention, GMLC  108  and SMLC-llO may communicate with one another using a TCP/IP or Ethernet connection that may be initiated by GMLC  108  acting as a client and SLMC  110  acting as a server. When the communication session is established, an application level handshake may be required to ensure that both platforms are communicating with the correct application. A successful handshake may create an RPS interface link in which a mobile unit location related transaction can proceed.  
         [0076]     One TCP/IP session may constitute one RPS interface link. In some embodiments, GMLC  108  may establish more than one communication session to create multiple RPS interface links. In this case, each link may be created by successful application level handshaking. A communications session may terminate if either GMLC  108  or SMLC  110  does not receive a status communication from the other within a predetermined period of time (e.g., 30 seconds).  
         [0077]     In one embodiment of the present invention, RSP messages relating to the same positioning transaction may be sent and received over the same RSP interface link if multiple such links are active. This may be done to prevent information from these RSP messages from being intermixed in the TCP/IP byte stream.  
         [0078]     Information processed by SMLC  110  and GMLC  108  in accordance with the RPS standard disclosed herein may be converted back into standard GPRS format at GMLC  108  or gateway  106  for transmission of requested information back to mobile unit  102  via wireless network  104 . This alleviates the need to update mobile units  102  or other portions of the wireless network  104  to recognize RSP messages. Moreover, GMLC  108 , SMLC  110 , and mobile unit  102  may include or communicate with or include a mapping application program such as Mapquest™ to further process the position information requested into a map type or other format for ease of comprehension by the user.  
         [0079]      FIG. 2  illustrates an alternate embodiment of the present invention wherein gateway  106  interfaces directly with SMLC  110  rather than through GMLC  108 . With this configuration, SMLC  110  receives location requests from GMLC  108  using the RSP messages described above and SMLC  110  connects to gateway  106 . SMLC  110  may convert the RSP messages back into GPRS format and transmit them to mobile unit  102  through gateway  106  and wireless network  104 .  
         [0080]     Flow chart  200  in  FIG. 3  shows some of the steps involved in providing location information to mobile unit  102 , application  112 , or client  114  in accordance with the principles of the present invention. At step  202 , the location of mobile unit  102  may be requested. This request may come from mobile unit  102 , location application  112 , and/or location client  114  depending on the particular implementation in use. Next, at step  204 , the location request may be routed to SMLC  110  via GMLC  108 . However, in some embodiments, SMLC  110  may receive the location request from gateway  106  directly (if from mobile unit  102 ) or from GMLC  108  (if from location application  112  or location client  114  (e.g., see  FIG. 2 )).  
         [0081]     At step  206  SMLC  110  may send a location request to mobile unit  102  such as GPS or other positioning system information. In response to receiving such information, mobile unit  102  may send information/data generally indicative of its position (such as psuedo-range information) back to SMLC  110  at step  208 . Next, SMLC  110  may process this information, possibly along with other positioning information received from an external source, to determine the location of mobile unit  102  at step  210 . At step  212 , this location information may be sent to external application and/or clients such as, for example, mobile unit  102 , location application  112 , and/or location client  114 . Next, at step  214 , before final transmission to its destination, the location information/data may be converted or mapped from and internal SMLC/GMLC communication format such as the format disclosed herein to standard GPRS, GSM CDMA or other communication format for processing by that application/client.  
         [0082]     Thus, systems and methods for locating and communicating location information to a mobile unit are provided. It will be understood that the foregoing is only illustrative of the principles of the invention and that various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention. Accordingly, such embodiments will be recognized as within the scope of the present invention.  
         [0083]     Persons skilled in the art will appreciate that the present invention can be practiced by other than the described embodiments, which are presented for purposes of illustration rather than of limitation and that the present invention is limited only by the claims that follow.