Abstract:
A technique for estimating the geo-location of a mobile station, based on signal measurements or other data that are obtained from both the control plane and the user plane. Through the coordination of obtaining signal measurements from both planes, the disclosed method and system make location estimations of greater accuracy possible. A data-processing system is configured to receive requests for location estimates from a location-based services (LBS) client or from a different source. The illustrative data-processing system then coordinates the acquisition of location data across both the control plane and the user plane, and correlates the data. The correlated location data can be subsequently used to generate a location estimate.

Description:
FIELD OF THE INVENTION 
     The present invention relates to wireless networks in general, and, more particularly, to locating mobile stations by using control plane and user plane location data. 
     BACKGROUND OF THE INVENTION 
       FIG. 1  depicts a schematic diagram of a portion of wireless telecommunications network  100  that is available in the prior art. Wireless network  100  comprises: mobile switching center (“MSC”)  101 , base station controller (“BSC”)  103 , base station  105 , serving mobile location center (“SMLC”)  107 , gateway mobile location center (“GMLC”)  109 , secure user plane location (SUPL) location platform (“SLP”)  111 , location-based services (“LBS”) client  113 , and mobile station  150 , interrelated as shown. At least some of the aforementioned elements communicate with each other via computer network  130 . 
     Wireless network  100  as illustrated in  FIG. 1  is a wireless network that is configured to operate according to the Global System for Mobile Communications (“GSM”) standards. In some configurations, wireless network  100  can be a wireless network that is based on a different 3rd Generation Partnership Project (“3GPP”) cellular network standard, such as Universal Mobile Telecommunications System (“UMTS”) or Long-Term Evolution (“LTE”), or based on a 3rd Generation Partnership Project 2 (“3GPP”) cellular network standard, such as Code Division Multiple Access (“CDMA”). 
     Mobile switching center (“MSC”)  101  is a wireless network element that, among other functions, provides mobility management and primary call support, for voice and other services, along with connectivity to the Public Switched Telephone Network (“PSTN”). 
     Base station controller (“BSC”)  103  is responsible for signaling between a mobile station and the main switching elements of the network such as mobile switching center  101 . Typically, base station controller  103  controls a plurality of base stations  105 , but only one base station  105  is illustrated here for simplicity. 
     Base station  105  is responsible for the wireless radio frequency (“RF”) communication link to the mobile stations in the area. Base station  105  serves a cell of wireless network  100  and has a unique cell identification within the network. A group of cells define a “location area.” As illustrated in  FIG. 1 , base station  105  is the serving base station to mobile station  150 , i.e., provides the necessary service that enables voice and/or data services to mobile station  150 . 
     Serving mobile location center (“SMLC”)  107  provides standards-based, control plane (CP) locating, by i) collecting information from mobile station  150  and/or serving base station  105  via base station controller  103  and ii) based on the information collected, estimating the mobile&#39;s location to a certain level of accuracy (e.g., to within a radius of 300 meters). The SMLC performs location estimation via one or more methods that can include cell-ID (CID), cell ID plus timing information (CI+TI), enhanced cell ID (E-CID), observed time difference of arrival (OTDOA), assisted Global Positioning System (A-GPS), or radio-frequency pattern-matching (RFPM), for example and without limitation. In providing a location estimate via a control plane location procedure, these methods utilize signal measurements and/or other data (e.g., handset-calculated location, etc.) that are obtained via the control plane and from the mobile station and/or serving base station. 
     Gateway mobile location center (“GMLC”)  109  is an element of the wireless network that typically interfaces with external location services systems that provide higher-level applications. Within wireless network  100 , gateway mobile location center  109  transmits location requests to mobile switching center  101  and receives location estimates that were generated by serving mobile location center  107  and transmitted therefrom “upstream” to gateway mobile location center  109 . 
     SUPL location platform (“SLP”)  111  provides functionality similar to that of SMLC  107 , except through the user plane (UP). The location estimation performed by SLP  111  utilizes signal measurements and/or other data (e.g., handset-calculated location, etc.) that are obtained via the user plane from mobile station  150 . 
     Location-based services (“LBS”) client  113  requests and uses location data to control features, such as deploying emergency resources in response to E-911 calls and delivering marketing information to customers in a specific geographical area, for example and without limitation. 
     Mobile station  150  is illustratively a GSM cellular telephone. As such, mobile station  150  wirelessly receives and/or transmits signals from one or more base stations  105 . At least some of the signals that are exchanged between mobile station  150  and base station  105  are used in location estimates that involve the control plane or in location estimates that involve the user plane. 
     SUMMARY OF THE INVENTION 
     The problem with performing location estimation in at least some prior-art wireless networks is that control plane (CP) location procedures and user plane (UP) location procedures are segregated. In other words, a location-based services client may request a location estimate that is either based on a CP location procedure or based on a UP location procedure. To the extent that both a control-plane location estimate and a user-plane location estimate are available for a given mobile station, they are often based on data that are obtained at different times; in any event, the data has been separately developed into the location estimates. Depending on the circumstances, this can limit the accuracy of a location estimate of a mobile station. 
     The present invention enables a technique for estimating the geo-location of a mobile station, based on signal measurements that are obtained from both the control plane and the user plane. Through the careful coordination of obtaining signal measurements from both planes, the method and system of the illustrative embodiment of the present invention advantageously make location estimations of greater accuracy possible, compared to at least some methods and systems of the prior art. 
     In accordance with the illustrative embodiment of the present invention, a coordinating data-processing system is configured to receive requests for location estimates from a location-based services (LBS) client or, alternatively, from a different source. The illustrative data-processing system then coordinates the acquisition of location data across both the control plane and the user plane. Through a clever usage of numeric values within pre-existing messages and bit-fields within those messages, the system of the illustrative embodiment obtains and correlates the data across the two planes and stores the correlated data into databases. The system identifies each set of correlated data as such by tagging the data with an identification. The stored, correlated data can be subsequently used to generate a location estimate. Such a location estimate is associated with greater accuracy, at least when compared to some control-plane-only estimates, some user-plane-only estimates, or some estimates generated from uncorrelated data, in the prior art. 
     The coordination of location data as disclosed herein is in contrast to at least some prior-art techniques in which either a gateway mobile location center (GMLC) receives the location requests directly or a secure user plane location platform (SLP) receives the location requests directly, and in which those prior-art techniques result in location estimates that do not reflect a coordinated usage of both control plane and user plane location data that are correlated with each other. 
     An illustrative location estimation system comprises: a first server computer that is configured to: i) receive a location request from a location-based services client, wherein the location request specifies a particular mobile station, ii) transmit, in response to receiving the location request, a first message comprising a first-message bit-field and a second message comprising a second-message bit-field, and iii) transmit a location estimate to the location-based services client, wherein the location estimate is based on both i) a first non-empty set of location data that is obtained through a control plane and ii) a second non-empty set of location data that is obtained through a user plane; a second server computer that is configured to: i) receive the first message, and ii) acquire, through the control plane, the first set of location data in response to receiving the first message and dependent on the value represented in the first-message bit-field; and a third server computer that is configured to: i) receive the second message, and ii) acquire, through the user plane, the second set of location data in response to receiving the second message and dependent on the value represented in the second-message bit-field. 
     An illustrative method of location estimation comprises: receiving, by a first server computer, a location request from a location-based services client, wherein the location request specifies a particular mobile station; transmitting, by the first server computer and in response to receiving the location request, i) a first message comprising a first-message bit-field to a control plane server and ii) a second message comprising a second-message bit-field to a user plane server; acquiring, by the control plane server and through a control plane, a first set of location data based on the first message and dependent on the value represented in the first-message bit-field; acquiring, by the user plane server and through a user plane, a second set of location data based on the second message and dependent on the value represented in the second-message bit-field; and transmitting, by the first server computer, a location estimate to the location-based services client, wherein the location estimate is based on both i) the first non-empty set of location data that is obtained through the control plane and ii) the second non-empty set of location data that is obtained through the user plane. 
     Another illustrative method of location estimation comprises: receiving, by a first server computer, a location request from a location-based services client, wherein the location request specifies a particular mobile station, wherein the location-based services client is identified by an identification (ID) present in the location request; transmitting, by the first server computer and in response to receiving the location request, at least one of i) a first message comprising a first-message bit-field to a control plane server and ii) a second message comprising a second-message bit-field to a user plane server, wherein whether each of the first message and second message is transmitted is based on the ID of the location-based services client; acquiring at least one of i) a first set of location data based on the first message and dependent on the value represented in the first-message bit-field and ii) a second set of location data based on the second message and dependent on the value represented in the second-message bit-field; and transmitting, by the first server computer, a location estimate to the location-based services client, wherein the location estimate is based on at least one of i) the first non-empty set of location data that is obtained via the control plane server and ii) the second non-empty set of location data that is obtained via the user plane server. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts a schematic diagram of a portion of wireless telecommunications network  100  that is available in the prior art. 
         FIG. 2  depicts a schematic diagram of the salient portions of wireless telecommunications network  200  in accordance with the illustrative embodiment of the present invention. 
         FIG. 3  depicts a block diagram comprising the salient elements of the data-processing hardware platform for hybrid UP CP anchor server  215  according to the illustrative embodiment. 
         FIGS. 4A, 4B, and 4C  depict some salient operations of method  400  according to an illustrative embodiment of the present invention, in which control plane and user plane location sessions are coordinated. 
     
    
    
     DETAILED DESCRIPTION 
     The following documents are incorporated by reference herein:
         “Mobile Location Protocol”, Version 3.2, Open Mobile Alliance   3GPP TS 29.003, “Mobile Application Protocol”   3GPP TS 43.059 Release 6, “Functional Stage 2 Descriptions of Location Services in GERAN”   3GPP TS 49.031 Release 6, “Location Services (LCS); Base Station System Application Part LCS Extension (BSSAP-LE)”   3GPP TS 48.071 Release 6, “Serving Mobile Location Center-Base Station System (SMLC-BSS) interface; Layer 3 specification (BSSLAP)”   3GPP TS 44.031 Release 6, “LCS; Mobile Station (MS)-SMLC Radio Resource LCS Protocol (RRLP)”   3GPP TS 25.305 Release 7, “Stage 2 functional specification of UE positioning in UTRAN”   3GPP TS 25.453 Release 7, “UTRAN Iupc interface Positioning Calculation Application Part (PCAP) signaling”   3GPP TS 36.305 Release 10, “Stage 2 functional specification of User Equipment (UE) positioning in E-UTRAN”   3GPP TS 29.171 Release 10, “LCS Application Protocol (LCS-AP) between the Mobile Management Entity (MME) and Evolved Serving Mobile Location Center (E-SMLC); SLs interface”   3GPP TS 36.455 Release 10, “LTE Positioning Protocol A (LPPa)”   3GPP TS 36.355 Release 10, “LTE Positioning Protocol (LPP)”   3GPP TS 23.032, “Universal Geographical Area Description”       

     For the purposes of this specification, the following terms and their inflected forms are defined as follows:
         The term “location” is defined as a zero-dimensional point, a finite one-dimensional path segment, a finite two-dimensional surface area, or a finite three-dimensional volume. Thus, a location can be defined, for example, by geographic coordinates or by a perimeter.   The term “mobile station” is defined as a device that is capable of telecommunications without a wire or tangible medium. A wireless terminal can be mobile or immobile. A wireless terminal can transmit or receive, or transmit and receive. As is well known to those skilled in the art, a wireless terminal is also commonly called a cell phone, a pager, a wireless transmit/receive unit (WTRU), a user equipment (UE), a wireless terminal, a fixed or mobile subscriber unit, a pager, a cellular telephone (i.e., “cellphone”), a personal digital assistant (PDA), a computer, and any other type of device capable of operating in a wireless environment (e.g., one that is defined by 3GPP- or 3GPP2-based protocols, etc.) are examples of wireless terminals.   The term “control plane” is defined as the part of a data communications network that carries signaling traffic.   The term “user plane” is defined as the part of a data communications network that carries user-level data.   The term “server” is defined as at least one of i) a running instance of some software capable of accepting requests from clients and ii) the computer device that such a server runs on (i.e., “server computer”).       

       FIG. 2  depicts a schematic diagram of the salient portions of wireless telecommunications network  200  in accordance with the illustrative embodiment of the present invention. Wireless telecommunications network  200  comprises: mobile switching center (“MSC”)  101 , base station controller (“BSC”)  103 , base station  105 , enhanced serving mobile location center (“xSMLC”)  207 , enhanced gateway mobile location center (“xGMLC”)  209 , enhanced secure user plane location (SUPL) location platform (“xSLP”)  211 , location-based services (“LBS”) client  113 , hybrid UP CP anchor server  215 , hybrid location engine  217 , user plane (UP) database  221 , control plane (CP) database  219 , and mobile station  150 , interrelated as shown. For pedagogical purposes, the aforementioned elements refer to hardware devices that, as data-processing systems, execute corresponding functions that are described herein. In some embodiments of the present invention, however, at least some of the aforementioned elements can refer to the functions themselves, as those who are skilled in the art will appreciate after reading this specification. 
     Wireless network  200  uses the GSM protocol, but it will be clear to those skilled in the art, after reading the present disclosure, how to make and use alternative embodiments of the present invention that use another protocol (e.g., CDMA, TDMA, UMTS, LTE, another 3GPP protocol, another 3GPP2 protocol, etc.). In other words, the systems and methods disclosed herein are agnostic of the particular underlying radio transmission architecture employed in the wireless network, as will be clear after reading the present disclosure. 
     The illustrative embodiment is described using GSM-specific terminology, but it will be clear to those skilled in the art what the appropriate terms are for non-GSM networks. 
     Mobile switching center  101 , base station controller  103 , base station  105 , location-based services (LBS) client  113 , and wireless telecommunications terminal  150  are well known in the prior art and are described above. For simplicity, distinctions between a serving mobile switching center and other mobile network entities are kept to a minimum herein as such distinctions are well known in the art. 
     In some embodiments of the present invention, wireless network  200  has packet data capability, in addition to the service capabilities provided by the MSC. A general packet radio service (“GPRS”) support node (“GPRS support node”), as is well known in the art, is analogous in some functions to mobile switching center  101 , but differs from mobile switching center  101  in that it supports packet data services to the mobile stations. GPRS support nodes are well known in the art. 
     Enhanced serving mobile location center (“xSMLC”)  207  provides standards-based, control plane (CP) locating, by i) collecting information from mobile station  150  and/or serving base station  105  via base station controller  103  and ii) based on the information collected, estimating the mobile&#39;s location to a certain level of accuracy. In accordance with the illustrative embodiment of the present invention, xSMLC  207  performs location estimation via the Wireless Location Signature (WLS™) location method from Polaris Wireless, Inc. In some embodiments of the present invention, xSMLC  207  can use one or more other location methods that are well-known in the art. In addition, xSMLC  207  is capable of making location assistance data and location estimates obtained via the control plane available to hybrid location engine  217 , via control plane (CP) database  219 . 
     xSMLC  207  is based on a platform such as, but not limited to, SMLC  107 . As those who are skilled in the art will appreciate after reading this disclosure, xSMLC  207  can alternatively be based on SAS (standalone SMLC) in accordance with the UMTS protocol, E-SMLC in accordance with the LTE protocol, or a different mobile location platform entirely. 
     Enhanced gateway mobile location center (“xGMLC”)  209  performs standard functions that are analogous to the role of gateway mobile location center  109  in wireless network  100 , with the enhancement that it can instruct one or more downstream xSMLCs, such as xSMLC  207 , to perform their role in providing control plane location data in support of interrelating that data with user plane location data, in accordance with the illustrative embodiment of the present invention. As devised in the illustrative embodiment, enhanced gateway mobile location center  209  presents itself to other legacy elements of wireless network  200  with the identity of a legacy gateway mobile location center, thus enabling legacy signaling to occur logically to/from the other legacy elements. 
     Enhanced SUPL location platform (“xSLP”)  211  provides functionality similar to that of xSMLC  207 , except through the user plane (UP) instead of the control plane. The location estimation performed by xSLP  211  utilizes signal measurements and/or other data (e.g., handset-calculated location, etc.) that are obtained via the user plane from mobile station  150 . In addition, xSLP  211  is capable of making location assistance data and location estimates obtained via the user plane available to hybrid location engine  217 , via user plane (UP) database  221 . xSLP  211  is based on a platform such as, but not limited to, SLP  111 . 
     Hybrid UP CP anchor server  215  correlates the control plane and user plane location sessions, in accordance with the illustrative embodiment of the present invention. Anchor server  215  also acts as an interface with the application that requests the location of the mobile station, the application being part of LBS client  113 . Server  115  also instructs xGMLC  209  and xSLP  211  to perform an enhanced user plane/control plane location estimation procedure, which results in UP and CP data being obtained. Server  215  also instructs hybrid location engine  217  to correlate the UP and CP data with each other, instead of performing a conventional control plane location procedure or a conventional user plane location procedure independently or alone. In performing all of this, hybrid UP CP anchor server  215  is said to be coordinating the acquisition of both control plane and user plane location data, thereby enabling the use of both types of data in a hybrid location estimation. Anchor server  215  is further described below and in  FIG. 3 . 
     Hybrid location engine  217  combines all available location assistance data and estimated locations to produce a hybrid location estimate. 
     Control plane (CP) database  219  stores the location assistance data and estimated locations obtained using the control plane location session. 
     User plane (UP) database  221  stores the location assistance data and estimated locations obtained using the user plane location session. 
     Two or more of the aforementioned elements communicate with each other via computer network  230 , in well-known fashion. Computer network  230  can comprise one or more distinct networks that operate in accordance with one or more different protocols. 
     Each of the aforementioned data-processing systems (e.g., server computers, etc.) and databases are described as being physically distinct devices, in accordance with the illustrative embodiment of the present invention. As those who are skilled in the art will appreciate after reading this specification, however, two or more of the aforementioned elements can be implemented within single devices. For example and without limitation, the functionalities of xGMLC  209  and anchor server  215  can be implemented within the same server computer. 
     Additionally, the same equipment vendor can provide two or more of the aforementioned data-processing systems. For example and without limitation, the same vendor can provide xSMLC  207 , xGMLC  209 , and/or xSLP  211 . 
       FIG. 3  depicts a block diagram comprising the salient elements of the data-processing hardware platform for anchor server  215  according to the illustrative embodiment. Anchor server  215  is a data-processing system that comprises: 
     processor  301 , memory  302 , and network interface module  303 . Anchor server  301  comprises the hardware and requisite software necessary to execute the specialized application software, receive signals, transmit signals, and process data such that it can perform the operations described herein. 
     Processor  301  is a general-purpose processor that is configured to execute operating system  311  and application software  312 , and to populate, amend, use, and manage database  313 , as described in detail below and in the accompanying figures. For the purposes of this specification, a “processor” is defined as one or more computational elements, whether co-located or not and whether networked together or not. Processor  301  is well known in the art. 
     Memory  302  is non-transitory and non-volatile computer storage memory technology that is well known in the art (e.g., flash memory, etc.). Memory  302  is configured to store operating system  311 , application software  312 , and database  313 . The operating system is a collection of software that manages, in well-known fashion, server  215 &#39;s hardware resources and provides common services for computer programs, such as those that constitute the application software. The application software that is executed by processor  301  enables server  215  to perform the functions disclosed herein. Database  313  comprises information relevant to each location request of each mobile station being location, wherein the location requests can arrive from one or more location-based services clients. Such information includes LBS client identification (ID), mobile station ID (e.g., MSISDN, etc.), accuracy required, time or delay, type of location estimation (e.g., CP-based, UP-based, hybrid, etc.), and correlation ID, for example and without limitation. Memory  302  is well known in the art. 
     Network interface module  303  is a component that enables anchor server  215  to communicate electronically with other components internal and external to wireless network  200 . For example, module  303  enables communication pathways to/from LBS client  113 , xGMLC  209 , hybrid location engine  217 , and other elements of wireless network  200 . Network interface module  303  is well known in the art. 
     The specialized application software that is executed on the hardware platform by anchor server  215  enables the system to perform at least some of the operations in method  400 , which is depicted in  FIGS. 4A through 4C . It will be clear to those skilled in the art, after reading the present disclosure, that the data processing hardware platform of anchor server  215  can be embodied as a multi-processor platform, as a server computer, as a computer device, as a sub-component of a larger computing platform, or in some other computing environment—all within the scope of the present invention. It will be clear to those skilled in the art, after reading the present disclosure, how to make and use the data-processing hardware platform for anchor server  215 . 
     In at least some embodiments of the present invention, the block diagram depicted in  FIG. 3  comprises the salient elements of the data-processing hardware platform or platforms for xGMLC  209 , xSLP  211 , and/or hybrid location engine  217 . 
       FIGS. 4A through 4C  depict some salient operations of method  400  according to an illustrative embodiment of the present invention, in which control plane and user plane location sessions are coordinated. In regard to method  400 , it will be clear to those skilled in the art, after reading the present disclosure, how to make and use alternative embodiments of the disclosed methods wherein the recited operations, sub-operations, and messages are differently sequenced, grouped, or sub-divided—all within the scope of the present invention. Also, it will be further clear to those skilled in the art, after reading the present disclosure, how to make and use alternative embodiments of the disclosed methods wherein at least some of the described operations, sub-operations, and messages are optional, are omitted, or are performed by other elements and/or systems. 
     At task  401 , LBS client  113  generates a request for a location estimate and transmits the location request via message  403 . The location request comprises an identification of the mobile station for which a location estimate is being requested. In some embodiments of the present invention, the identification comprises a mobile station international subscriber directory number (MSISDN). In some other embodiments of the present invention, a different identification can be included in the location request. In order to ensure proper routing of the message to anchor server  215 , a technician can configure a destination address for message  403  that corresponds to the anchor server, in well-known fashion. 
     At task  405 , anchor sever  215  receives the location request and starts a mobile terminated location request (MTLR) procedure by transmitting the location request via message  407  to xGMLC  209 . This request comprises i) a flag that indicates that hybrid location estimation is required and ii) the mobile station identification (e.g., MSISDN, etc.) received in message  403 . In accordance with the illustrative embodiment, the flag value is conveyed within the QoP bit-field, while in some other embodiments the flag value can be conveyed within a different bit-field. 
     As part of a standardized protocol, the QoP bit-field and also the QoS bit-field mentioned below comprise two information elements: i) accuracy required and ii) time or delay. The “accuracy required” element is used to specify the accuracy of the location estimate that is required by the requesting client. The “time or delay” element is used to specify how long the client can wait for a location estimate to be returned to it. A more accurate estimate generally needs more time. As those who are skilled in the art will appreciate after reading this specification, one or both of these elements can be used to represent the hybrid location flag. Furthermore, it will be clear to those skilled in the art, after reading this specification, how to select a particular numeric value to denote the particular type of hybrid location processing, or other type of location processing, to be invoked (e.g., “99” for hybrid, etc.) without interfering with already-standardized processes. 
     In some embodiments of the present invention, a particular flag value can be used to denote a particular action to be taken. For example and without limitation, various values can be used to denote i) hybrid location estimation, ii) only control-plane (CP) location, iii) only user-plane (UP) location, iv) CP location followed by UP location if CP location fails, v) UP location followed by CP location if UP locations fails, and so on. Server  215  can decide which action is to be taken based on one or more of i) the particular client that is requesting a location estimate, ii) the accuracy required, iii) how quickly the client needs the response, and so on, for example and without limitation, in which any or all of these parameters can be provided by LBS client  113  or provided from a different source. 
     Additionally, in some embodiments of the present invention, a particular flag value, or a value of a second type of flag, can be used to denote whether the xSMLC and/or the xSLP provides i) a location estimate, ii) a measurement report, or iii) both a location estimate and measurement report. 
     At task  409 , xGMLC  209  transmits the location request via message  411  to MSC  101 , which then transmits it to BSC  103 . The location request is formatted and transmitted according to the standard protocol except that the QoS bit-field, instead of containing the conventional QoS values, now contains a flag value that indicates that this location request is in accordance with the hybrid procedure. In some other embodiments, this flag can be part of some other bit-field. 
     At task  413 , BSC  103  transmits the location request via message  415  to xSMLC  207 . 
     At task  417 , xSMLC  207 , upon detecting the hybrid flag in message  415  (i.e., in the QoS bit-field), does not perform the usual location request and instead performs the procedure directed by the hybrid flag. This includes collecting various types of measurement reports (MR) as measured by one or more base stations  105  and/or mobile station  150 . It might include, either in the alternative or additionally, obtaining a location estimate (e.g., A-GPS from the handset, etc.). This collecting and obtaining is performed as per the standard protocol without involving any change in the existing wireless network or mobile station. 
     At task  419 , once all of the MRs and/or location estimate are collected or determined, they are transmitted via message  421  to control plane database  219 , based on the hybrid flag being set. The xSMLC  207  tags this data with a unique correlation identification for the control plane (“CP ID”). Database  219  stores the data, including the corresponding CP ID, at task  423  for future use. 
     At task  425 , the same CP ID is also encoded in the latitude and longitude bit-fields of the response to the original location request, and is transmitted to xGMLC  209  via message  427 , by way of BSC  103  and MSC  101 . In the prior art, representations of latitude and longitude are used, at least in part, to define shapes such as a circle, a polygon, and so on. Such shapes are presented as one or more latitude/longitude sets and associated parameters that define the particular shape. For example, a circle is defined in terms of the latitude/longitude of its center and a radius (e.g., in meters, etc.) In accordance with the illustrative embodiment of the present invention, these representations are considered, when using the latitude/longitude bit-fields to represent the CP ID, in order to avoid confusion as to how the bit-fields are interpreted by a receiving data-processing system. 
     At task  429 , xGMLC  209  forwards the response to anchor server  215  via message  431 . Server  215  stores the information contained within message  431  for future use, including the CP ID. 
     At task  433 , in response to having received message  403 , anchor server  215  starts the user plane location session by transmitting the location request to xSLP  211  via message  435 , concurrently with the MTLR procedure described above. This request comprises i) a flag that indicates that UP data is to be made available and ii) the mobile station identification (e.g., MSISDN, etc.) received in message  403 . In accordance with the illustrative embodiment, the flag value is conveyed within the QoP bit-field, while in some other embodiments the flag value can be conveyed within a different bit-field. Task  433  and/or the subsequent tasks that are described below can be performed concurrently with the MTLR procedure described above or sequential to that procedure (i.e., before or after). 
     At task  441 , xSLP  211 , upon detecting the hybrid flag being set in message  435  (i.e., in the QoP bit-field), does not perform the usual location request and instead performs the enhanced procedure of the illustrative embodiment. This includes collecting various types of measurement reports (MR) as measured by mobile station  150 . It might include, either in the alternative or additionally, obtaining the A-GPS-based location from the handset. This collecting and obtaining is performed as per the standard protocol without involving any change in the existing wireless network or mobile station. 
     At task  443 , once all of the MRs and/or A-GPS location estimate are collected, they are transmitted via message  445  to user plane database  221 , based on the hybrid flag being set. The xSLP  211  tags this data with a unique correlation identification for the user plane, which comprises the MSISDN in accordance with the illustrative embodiment. In some other embodiments of the present invention, the correlation identification can comprise a different identification. Database  221  stores the data at task  447  for future use. 
     Optionally, at task  449 , this same ID (i.e., MSISDN) is also encoded in the latitude and longitude bit-fields of the response to the original location request, and is transmitted to anchor server  215  via message  451 . Server  215  stores the information contained within message  451  for future use. 
     At task  457 , in response having received both messages  431  and  451 , anchor server  215  notifies hybrid location engine  217  to perform hybrid location estimation, by transmitting message  459  containing the correlation IDs for the control plane (i.e., CP ID) and for the user plane (i.e., MSISDN). In some alternative embodiments of the present invention, server  215  notifies engine  217  after having received at least one of messages  431  and  451 . 
     At task  461 , location engine  217  forwards the correlation IDs for the control plane and user plane received in message  459 , to control plane database  219  via message  463  and to user plane database  221  via message  465 , respectively. 
     At task  467 , control plane database  219  accesses all of the data it had previously stored at task  425  that were tagged with the correlation ID for the control plane received in message  463 , and transmits the data to location engine  217  via message  469 . 
     At task  471 , user plane database  221  accesses all of the data it had previously stored at task  447  that were tagged with the correlation ID for the user plane received in message  465 , and transmits the data to location engine  217  via message  473 . 
     At task  475 , hybrid location engine  217  generates a location estimate of mobile station  150  based on both sets of data received in messages  469  and  473 . For example and without limitation, engine  217  can i) estimate, based on the control plane location data, that the mobile station is at a first location, ii) estimate, based on the user plane location data, that the mobile station is at a second location, and iii) combine the first and second location estimates to conclude that the mobile station is at a particular location that is a hybrid of the first and second locations. Alternatively, engine  217  can combine the user plane location data and control plane location data to conclude that the mobile station is at a third location. 
     In some alternative embodiments of the present invention, engine  217  generates a location estimate of mobile station  150  in a manner consistent with the particular flag value described above and in task  405 . 
     At task  477 , location engine  477  transmits via message  479  the location estimate generated at task  475 , to anchor server  215 . 
     At task  481 , anchor server  215  forwards the location estimate to LBS client  113  via message  483 . 
     It is to be understood that the disclosure teaches just one example of the illustrative embodiment and that many variations of the invention can easily be devised by those skilled in the art after reading this disclosure and that the scope of the present invention is to be determined by the following claims.